WorldWideScience

Sample records for flexible memory devices

  1. Flexible organic memory devices with multilayer graphene electrodes.

    Science.gov (United States)

    Ji, Yongsung; Lee, Sangchul; Cho, Byungjin; Song, Sunghoon; Lee, Takhee

    2011-07-26

    We fabricated 8 × 8 cross-bar array-type flexible organic resistive memory devices with transparent multilayer graphene (MLG) electrodes on a poly(ethylene terephthalate) substrate. The active layer of the memory devices is a composite of polyimide and 6-phenyl-C61 butyric acid methyl ester. The sheet resistance of the MLG film on memory device was found to be ∼270 Ω/◻, and the transmittance of separated MLG film from memory device was ∼92%. The memory devices showed typical write-once-read-many (WORM) characteristics and an ON/OFF ratio of over ∼10(6). The memory devices also exhibited outstanding cell-to-cell uniformity with flexibility. There was no substantial variation observed in the current levels of the WORM memory devices upon bending and bending cycling up to 10 000 times. A retention time of over 10(4) s was observed without fluctuation under bending.

  2. Reduced graphene oxide based flexible organic charge trap memory devices

    Science.gov (United States)

    Rani, Adila; Song, Ji-Min; Jung Lee, Mi; Lee, Jang-Sik

    2012-12-01

    A nonvolatile organic transistor memory device was developed using layer-by-layer assembly of 3-aminopropyltriethoxysilane (APTES) and solution-processed, reduced graphene oxide (rGO) as the charge trapping layer on flexible substrates. Reduction of graphene oxide and successful adsorption of the rGO on APTES-covered substrates were confirmed. The organic memory devices based on rGO exhibited reliable programmable memory operations, confirmed by program/erase operations, data retention, and endurance properties. These methods can potentially play a significant role in the fabrication of next-generation flexible nonvolatile memory devices based on graphene materials.

  3. Ultrathin flexible memory devices based on organic ferroelectric transistors

    Science.gov (United States)

    Sugano, Ryo; Hirai, Yoshinori; Tashiro, Tomoya; Sekine, Tomohito; Fukuda, Kenjiro; Kumaki, Daisuke; Domingues dos Santos, Fabrice; Miyabo, Atsushi; Tokito, Shizuo

    2016-10-01

    Here, we demonstrate ultrathin, flexible nonvolatile memory devices with excellent durability under compressive strain. Ferroelectric-gate field-effect transistors (FeFETs) employing organic semiconductor and polymer ferroelectric layers are fabricated on a 1-µm-thick plastic film substrate. The FeFETs are characterized by measuring their transfer characteristics, programming time, and data retention time. The data retention time is almost unchanged even when a 50% compressive strain is applied to the devices. To clarify the origin of the excellent durability of the devices against compressive strain, an intermediate plane is calculated. From the calculation result, the intermediate plane is placed close to the channel region of the FeFETs. The high flexibility of the ferroelectric polymer and ultrathin device structure contributes to achieving a bending radius of 0.8 µm without the degradation of memory characteristics.

  4. Flexible non-volatile memory devices based on organic semiconductors

    Science.gov (United States)

    Cosseddu, Piero; Casula, Giulia; Lai, Stefano; Bonfiglio, Annalisa

    2015-09-01

    The possibility of developing fully organic electronic circuits is critically dependent on the ability to realize a full set of electronic functionalities based on organic devices. In order to complete the scene, a fundamental element is still missing, i.e. reliable data storage. Over the past few years, a considerable effort has been spent on the development and optimization of organic polymer based memory elements. Among several possible solutions, transistor-based memories and resistive switching-based memories are attracting a great interest in the scientific community. In this paper, a route for the fabrication of organic semiconductor-based memory devices with performances beyond the state of the art is reported. Both the families of organic memories will be considered. A flexible resistive memory based on a novel combination of materials is presented. In particular, high retention time in ambient conditions are reported. Complementary, a low voltage transistor-based memory is presented. Low voltage operation is allowed by an hybrid, nano-sized dielectric, which is also responsible for the memory effect in the device. Thanks to the possibility of reproducibly fabricating such device on ultra-thin substrates, high mechanical stability is reported.

  5. A flexible organic resistance memory device for wearable biomedical applications

    Science.gov (United States)

    Cai, Yimao; Tan, Jing; YeFan, Liu; Lin, Min; Huang, Ru

    2016-07-01

    Parylene is a Food and Drug Administration (FDA)-approved material which can be safely used within the human body and it is also offers chemically inert and flexible merits. Here, we present a flexible parylene-based organic resistive random access memory (RRAM) device suitable for wearable biomedical application. The proposed device is fabricated through standard lithography and pattern processes at room temperature, exhibiting the feasibility of integration with CMOS circuits. This organic RRAM device offers a high storage window (>104), superior retention ability and immunity to disturbing. In addition, brilliant mechanical and electrical stabilities of this device are demonstrated when under harsh bending (bending cycle >500, bending radius <10 mm). Finally, the underlying mechanism for resistance switching of this kind of device is discussed, and metallic conducting filament formation and annihilation related to oxidization/redox of Al and Al anions migrating in the parylene layer can be attributed to resistance switching in this device. These advantages reveal the significant potential of parylene-based flexible RRAM devices for wearable biomedical applications.

  6. A flexible organic resistance memory device for wearable biomedical applications.

    Science.gov (United States)

    Cai, Yimao; Tan, Jing; YeFan, Liu; Lin, Min; Huang, Ru

    2016-07-08

    Parylene is a Food and Drug Administration (FDA)-approved material which can be safely used within the human body and it is also offers chemically inert and flexible merits. Here, we present a flexible parylene-based organic resistive random access memory (RRAM) device suitable for wearable biomedical application. The proposed device is fabricated through standard lithography and pattern processes at room temperature, exhibiting the feasibility of integration with CMOS circuits. This organic RRAM device offers a high storage window (>10(4)), superior retention ability and immunity to disturbing. In addition, brilliant mechanical and electrical stabilities of this device are demonstrated when under harsh bending (bending cycle >500, bending radius mechanism for resistance switching of this kind of device is discussed, and metallic conducting filament formation and annihilation related to oxidization/redox of Al and Al anions migrating in the parylene layer can be attributed to resistance switching in this device. These advantages reveal the significant potential of parylene-based flexible RRAM devices for wearable biomedical applications.

  7. High-Performance Flexible Organic Nano-Floating Gate Memory Devices Functionalized with Cobalt Ferrite Nanoparticles.

    Science.gov (United States)

    Jung, Ji Hyung; Kim, Sunghwan; Kim, Hyeonjung; Park, Jongnam; Oh, Joon Hak

    2015-10-07

    Nano-floating gate memory (NFGM) devices are transistor-type memory devices that use nanostructured materials as charge trap sites. They have recently attracted a great deal of attention due to their excellent performance, capability for multilevel programming, and suitability as platforms for integrated circuits. Herein, novel NFGM devices have been fabricated using semiconducting cobalt ferrite (CoFe2O4) nanoparticles (NPs) as charge trap sites and pentacene as a p-type semiconductor. Monodisperse CoFe2O4 NPs with different diameters have been synthesized by thermal decomposition and embedded in NFGM devices. The particle size effects on the memory performance have been investigated in terms of energy levels and particle-particle interactions. CoFe2O4 NP-based memory devices exhibit a large memory window (≈73.84 V), a high read current on/off ratio (read I(on)/I(off)) of ≈2.98 × 10(3), and excellent data retention. Fast switching behaviors are observed due to the exceptional charge trapping/release capability of CoFe2O4 NPs surrounded by the oleate layer, which acts as an alternative tunneling dielectric layer and simplifies the device fabrication process. Furthermore, the NFGM devices show excellent thermal stability, and flexible memory devices fabricated on plastic substrates exhibit remarkable mechanical and electrical stability. This study demonstrates a viable means of fabricating highly flexible, high-performance organic memory devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Transparent and flexible write-once-read-many (WORM) memory device based on egg albumen

    Science.gov (United States)

    Qu, Bo; Lin, Qianru; Wan, Tao; Du, Haiwei; Chen, Nan; Lin, Xi; Chu, Dewei

    2017-08-01

    Egg albumen, as an important protein resource in nature, is an interesting dielectric material exhibiting many fascinating properties for the development of environmentally friendly electronic devices. Taking advantage of their extraordinary transparency and flexibility, this paper presents an innovative preparation approach for albumen thin film based write-once-read-many-times (WORM) memory devices in a simple, cost-effective manner. The fabricated device shows superior data retention properties including non-volatile character (over 105 s) and promising great read durability (106 times). Furthermore, our results suggested that the electric-field-induced trap-controlled space charge limited current (SCLC) conduction is responsible for the observed resistance switching effect. The present study may likely reveal another pathway towards complete see-through electrical devices.

  9. Effects of device size and material on the bending performance of resistive-switching memory devices fabricated on flexible substrates

    Science.gov (United States)

    Lee, Won-Ho; Yoon, Sung-Min

    2017-05-01

    The resistive change memory (RCM) devices using amorphous In-Ga-Zn-O (IGZO) and microcrystalline Al-doped ZnO (AZO) thin films were fabricated on plastic substrates and characterized for flexible electronic applications. The device cell sizes were varied to 25 × 25, 50 × 50, 100 × 100, and 200 × 200 μm2 to examine the effects of cell size on the resistive-switching (RS) behaviors at a flat state and under bending conditions. First, it was found that the high-resistance state programmed currents markedly increased with the increase in the cell size. Second, while the AZO RCM devices did not exhibit RESET operations at a curvature radius smaller than 8.0 mm, the IGZO RCM devices showed sound RS behaviors even at a curvature radius of 4.5 mm. Third, for the IGZO RCM devices with the cell size bigger than 100 × 100 μm2, the RESET operation could not be performed at a curvature radius smaller than 6.5 mm. Thus, it was elucidated that the RS characteristics of the flexible RCM devices using oxide semiconductor thin films were closely related to the types of RS materials and the cell size of the device.

  10. Nano-Floating Gate Memory Devices Composed of ZnO Thin-Film Transistors on Flexible Plastics

    Directory of Open Access Journals (Sweden)

    Park Byoungjun

    2011-01-01

    Full Text Available Abstract Nano-floating gate memory devices were fabricated on a flexible plastic substrate by a low-temperature fabrication process. The memory characteristics of ZnO-based thin-film transistors with Al nanoparticles embedded in the gate oxides were investigated in this study. Their electron mobility was found to be 0.18 cm2/V·s and their on/off ratio was in the range of 104–105. The threshold voltages of the programmed and erased states were negligibly changed up to 103 cycles. The flexibility, memory properties, and low-temperature fabrication of the nano-floating gate memory devices described herein suggest that they have potential applications for future flexible integrated electronics.

  11. Organic ferroelectric memory devices with inkjet-printed polymer electrodes on flexible substrates

    KAUST Repository

    Bhansali, Unnat Sampatraj

    2013-05-01

    Drop-on-demand piezoelectric inkjet-printing technique has been used to fabricate a functional cross-bar array of all-organic ferroelectric memory devices. The polymer-ferroelectric-polymer device consists of a ferroelectric copolymer P(VDF-TrFE) film sandwiched between inkjet-patterned, continuous, orthogonal lines of PEDOT:PSS polymer as the bottom and top electrodes. These devices exhibit well-saturated hysteresis curves with a maximum remnant polarization (Pr) = 6.7 μC/cm2, coercive field (E c) = 55 MV/m and a peak capacitance density of 45 nF/cm2. Our polarization fatigue measurements show that these devices retain ∼100% and 45% of their initial Pr values after 103 and 10 5 stress cycles, respectively. The overall performance and polarization retention characteristics of these ferroelectric capacitors with inkjet-printed polymer electrodes are comparable to metal and spin-cast polymer electrodes suggesting their potential use in large-area flexible electronics. © 2013 Elsevier Ltd. All rights reserved.

  12. 3D Printing of Shape Memory Polymers for Flexible Electronic Devices.

    Science.gov (United States)

    Zarek, Matt; Layani, Michael; Cooperstein, Ido; Sachyani, Ela; Cohn, Daniel; Magdassi, Shlomo

    2016-06-01

    The formation of 3D objects composed of shape memory polymers for flexible electronics is described. Layer-by-layer photopolymerization of methacrylated semicrystalline molten macromonomers by a 3D digital light processing printer enables rapid fabrication of complex objects and imparts shape memory functionality for electrical circuits.

  13. Structural Phase Transition Effect on Resistive Switching Behavior of MoS2 -Polyvinylpyrrolidone Nanocomposites Films for Flexible Memory Devices.

    Science.gov (United States)

    Zhang, Peng; Gao, Cunxu; Xu, Benhua; Qi, Lin; Jiang, Changjun; Gao, Meizhen; Xue, Desheng

    2016-04-01

    The 2H phase and 1T phase coexisting in the same molybdenum disulfide (MoS2 ) nanosheets can influence the electronic properties of the materials. The 1T phase of MoS2 is introduced into the 2H-MoS2 nanosheets by two-step hydrothermal synthetic methods. Two types of nonvolatile memory effects, namely write-once read-many times memory and rewritable memory effect, are observed in the flexible memory devices with the configuration of Al/1T@2H-MoS2 -polyvinylpyrrolidone (PVP)/indium tin oxide (ITO)/polyethylene terephthalate (PET) and Al/2H-MoS2 -PVP/ITO/PET, respectively. It is observed that structural phase transition in MoS2 nanosheets plays an important role on the resistive switching behaviors of the MoS2 -based device. It is hoped that our results can offer a general route for the preparation of various promising nanocomposites based on 2D nanosheets of layered transition metal dichalcogenides for fabricating the high performance and flexible nonvolatile memory devices through regulating the phase structure in the 2D nanosheets.

  14. Semiconductor-Free Nonvolatile Resistive Switching Memory Devices Based on Metal Nanogaps Fabricated on Flexible Substrates via Adhesion Lithography

    KAUST Repository

    Semple, James

    2017-01-02

    Electronic memory cells are of critical importance in modern-day computing devices, including emerging technology sectors such as large-area printed electronics. One technology that has being receiving significant interest in recent years is resistive switching primarily due to its low dimensionality and nonvolatility. Here, we describe the development of resistive switching memory device arrays based on empty aluminum nanogap electrodes. By employing adhesion lithography, a low-temperature and large-area compatible nanogap fabrication technique, dense arrays of memory devices are demonstrated on both rigid and flexible plastic substrates. As-prepared devices exhibit nonvolatile memory operation with stable endurance, resistance ratios >10⁴ and retention times of several months. An intermittent analysis of the electrode microstructure reveals that controlled resistive switching is due to migration of metal from the electrodes into the nanogap under the application of an external electric field. This alternative form of resistive random access memory is promising for use in emerging sectors such as large-area electronics as well as in electronics for harsh environments, e.g., space, high/low temperature, magnetic influences, radiation, vibration, and pressure.

  15. Preparation of MoS₂-polyvinylpyrrolidone nanocomposites for flexible nonvolatile rewritable memory devices with reduced graphene oxide electrodes.

    Science.gov (United States)

    Liu, Juqing; Zeng, Zhiyuan; Cao, Xiehong; Lu, Gang; Wang, Lian-Hui; Fan, Qu-Li; Huang, Wei; Zhang, Hua

    2012-11-19

    A facile method for exfoliation and dispersion of molybdenum disulfide (MoS2) with the aid of polyvinylpyrrolidone (PVP) is proposed. The resultant PVP-coated MoS2 nanosheets, i.e., MoS2-PVP nanocomposites, are well dispersed in the low-boiling ethanol solvent, facilitating their thin film preparation and the device fabrication by solution processing technique. As a proof of concept, a flexible memory diode with the configuration of reduced graphene oxide (rGO)/MoS2-PVP/Al exhibited a typical bistable electrical switching and nonvolatile rewritable memory effect with the function of flash. These experimental results prove that the electrical transition is due to the charge trapping and detrapping behavior of MoS2 in the PVP dielectric material. This study paves a way of employing two-dimensional nanomaterials as both functional materials and conducting electrodes for the future flexible data storage.

  16. 3D Printing: 3D Printing of Shape Memory Polymers for Flexible Electronic Devices (Adv. Mater. 22/2016).

    Science.gov (United States)

    Zarek, Matt; Layani, Michael; Cooperstein, Ido; Sachyani, Ela; Cohn, Daniel; Magdassi, Shlomo

    2016-06-01

    On page 4449, D. Cohn, S. Magdassi, and co-workers describe a general and facile method based on 3D printing of methacrylated macromonomers to fabricate shape-memory objects that can be used in flexible and responsive electrical circuits. Such responsive objects can be used in the fabrication of soft robotics, minimal invasive medical devices, sensors, and wearable electronics. The use of 3D printing overcomes the poor processing characteristics of thermosets and enables complex geometries that are not easily accessible by other techniques.

  17. Towards the development of flexible non-volatile memories.

    Science.gov (United States)

    Han, Su-Ting; Zhou, Ye; Roy, V A L

    2013-10-11

    Flexible non-volatile memories have attracted tremendous attentions for data storage for future electronics application. From device perspective, the advantages of flexible memory devices include thin, lightweight, printable, foldable and stretchable. The flash memories, resistive random access memories (RRAM) and ferroelectric random access memory/ferroelectric field-effect transistor memories (FeRAM/FeFET) are considered as promising candidates for next generation non-volatile memory device. Here, we review the general background knowledge on device structure, working principle, materials, challenges and recent progress with the emphasis on the flexibility of above three categories of non-volatile memories.

  18. Flexible non-volatile optical memory thin-film transistor device with over 256 distinct levels based on an organic bicomponent blend

    Science.gov (United States)

    Leydecker, Tim; Herder, Martin; Pavlica, Egon; Bratina, Gvido; Hecht, Stefan; Orgiu, Emanuele; Samorì, Paolo

    2016-09-01

    Organic nanomaterials are attracting a great deal of interest for use in flexible electronic applications such as logic circuits, displays and solar cells. These technologies have already demonstrated good performances, but flexible organic memories are yet to deliver on all their promise in terms of volatility, operational voltage, write/erase speed, as well as the number of distinct attainable levels. Here, we report a multilevel non-volatile flexible optical memory thin-film transistor based on a blend of a reference polymer semiconductor, namely poly(3-hexylthiophene), and a photochromic diarylethene, switched with ultraviolet and green light irradiation. A three-terminal device featuring over 256 (8 bit storage) distinct current levels was fabricated, the memory states of which could be switched with 3 ns laser pulses. We also report robustness over 70 write-erase cycles and non-volatility exceeding 500 days. The device was implemented on a flexible polyethylene terephthalate substrate, validating the concept for integration into wearable electronics and smart nanodevices.

  19. Flexible Hybrid Organic-Inorganic Perovskite Memory.

    Science.gov (United States)

    Gu, Chungwan; Lee, Jang-Sik

    2016-05-24

    Active research has been done on hybrid organic-inorganic perovskite materials for application to solar cells with high power conversion efficiency. However, this material often shows hysteresis, which is undesirable, shift in the current-voltage curve. The hysteresis may come from formation of defects and their movement in perovskite materials. Here, we utilize the defects in perovskite materials to be used in memory operations. We demonstrate flexible nonvolatile memory devices based on hybrid organic-inorganic perovskite as the resistive switching layer on a plastic substrate. A uniform perovskite layer is formed on a transparent electrode-coated plastic substrate by solvent engineering. Flexible nonvolatile memory based on the perovskite layer shows reproducible and reliable memory characteristics in terms of program/erase operations, data retention, and endurance properties. The memory devices also show good mechanical flexibility. It is suggested that resistive switching is done by migration of vacancy defects and formation of conducting filaments under the electric field in the perovskite layer. It is believed that organic-inorganic perovskite materials have great potential to be used in high-performance, flexible memory devices.

  20. Semiconductor-based, large-area, flexible, electronic devices

    Science.gov (United States)

    Goyal, Amit

    2011-03-15

    Novel articles and methods to fabricate the same resulting in flexible, large-area, triaxially textured, single-crystal or single-crystal-like, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  1. Flexible kernel memory.

    Science.gov (United States)

    Nowicki, Dimitri; Siegelmann, Hava

    2010-06-11

    This paper introduces a new model of associative memory, capable of both binary and continuous-valued inputs. Based on kernel theory, the memory model is on one hand a generalization of Radial Basis Function networks and, on the other, is in feature space, analogous to a Hopfield network. Attractors can be added, deleted, and updated on-line simply, without harming existing memories, and the number of attractors is independent of input dimension. Input vectors do not have to adhere to a fixed or bounded dimensionality; they can increase and decrease it without relearning previous memories. A memory consolidation process enables the network to generalize concepts and form clusters of input data, which outperforms many unsupervised clustering techniques; this process is demonstrated on handwritten digits from MNIST. Another process, reminiscent of memory reconsolidation is introduced, in which existing memories are refreshed and tuned with new inputs; this process is demonstrated on series of morphed faces.

  2. Flexible kernel memory.

    Directory of Open Access Journals (Sweden)

    Dimitri Nowicki

    Full Text Available This paper introduces a new model of associative memory, capable of both binary and continuous-valued inputs. Based on kernel theory, the memory model is on one hand a generalization of Radial Basis Function networks and, on the other, is in feature space, analogous to a Hopfield network. Attractors can be added, deleted, and updated on-line simply, without harming existing memories, and the number of attractors is independent of input dimension. Input vectors do not have to adhere to a fixed or bounded dimensionality; they can increase and decrease it without relearning previous memories. A memory consolidation process enables the network to generalize concepts and form clusters of input data, which outperforms many unsupervised clustering techniques; this process is demonstrated on handwritten digits from MNIST. Another process, reminiscent of memory reconsolidation is introduced, in which existing memories are refreshed and tuned with new inputs; this process is demonstrated on series of morphed faces.

  3. Resistive switching effect in the planar structure of all-printed, flexible and rewritable memory device based on advanced 2D nanocomposite of graphene quantum dots and white graphene flakes

    Science.gov (United States)

    Muqeet Rehman, Muhammad; Uddin Siddiqui, Ghayas; Kim, Sowon; Choi, Kyung Hyun

    2017-08-01

    Pursuit of the most appropriate materials and fabrication methods is essential for developing a reliable, rewritable and flexible memory device. In this study, we have proposed an advanced 2D nanocomposite of white graphene (hBN) flakes embedded with graphene quantum dots (GQDs) as the functional layer of a flexible memory device owing to their unique electrical, chemical and mechanical properties. Unlike the typical sandwich type structure of a memory device, we developed a cost effective planar structure, to simplify device fabrication and prevent sneak current. The entire device fabrication was carried out using printing technology followed by encapsulation in an atomically thin layer of aluminum oxide (Al2O3) for protection against environmental humidity. The proposed memory device exhibited attractive bipolar switching characteristics of high switching ratio, large electrical endurance and enhanced lifetime, without any crosstalk between adjacent memory cells. The as-fabricated device showed excellent durability for several bending cycles at various bending diameters without any degradation in bistable resistive states. The memory mechanism was deduced to be conductive filamentary; this was validated by illustrating the temperature dependence of bistable resistive states. Our obtained results pave the way for the execution of promising 2D material based next generation flexible and non-volatile memory (NVM) applications.

  4. Flexible graphene-PZT ferroelectric nonvolatile memory

    Science.gov (United States)

    Lee, Wonho; Kahya, Orhan; Tat Toh, Chee; Özyilmaz, Barbaros; Ahn, Jong-Hyun

    2013-11-01

    We report the fabrication of a flexible graphene-based nonvolatile memory device using Pb(Zr0.35,Ti0.65)O3 (PZT) as the ferroelectric material. The graphene and PZT ferroelectric layers were deposited using chemical vapor deposition and sol-gel methods, respectively. Such PZT films show a high remnant polarization (Pr) of 30 μC cm-2 and a coercive voltage (Vc) of 3.5 V under a voltage loop over ±11 V. The graphene-PZT ferroelectric nonvolatile memory on a plastic substrate displayed an on/off current ratio of 6.7, a memory window of 6 V and reliable operation. In addition, the device showed one order of magnitude lower operation voltage range than organic-based ferroelectric nonvolatile memory after removing the anti-ferroelectric behavior incorporating an electrolyte solution. The devices showed robust operation in bent states of bending radii up to 9 mm and in cycling tests of 200 times. The devices exhibited remarkable mechanical properties and were readily integrated with plastic substrates for the production of flexible circuits.

  5. Polymer Ferroelectric Memory for Flexible Electronics

    KAUST Repository

    Khan, Mohd Adnan

    2013-11-01

    With the projected growth of the flexible and plastic electronics industry, there is renewed interest in the research community to develop high performance all-polymeric memory which will be an essential component of any electronic circuit. Some of the efforts in polymer memories are based on different mechanisms such as filamentary conduction, charge trapping effects, dipole alignment, and reduction-oxidation to name a few. Among these the leading candidate are those based on the mechanism of ferroelectricity. Polymer ferroelectric memory can be used in niche applications like smart cards, RFID tags, sensors etc. This dissertation will focus on novel material and device engineering to fabricate high performance low temperature polymeric ferroelectric memory for flexible electronics. We address and find solutions to some fundamental problems affecting all polymer ferroelectric memory like high coercive fields, fatigue and thermal stability issues, poor breakdown strength and poor p-type hole mobilities. Some of the strategies adopted in this dissertation are: Use of different flexible substrates, electrode engineering to improve charge injection and fatigue properties of ferroelectric polymers, large area ink jet printing of ferroelectric memory devices, use of polymer blends to improve insulating properties of ferroelectric polymers and use of oxide semiconductors to fabricate high mobility p-type ferroelectric memory. During the course of this dissertation we have fabricated: the first all-polymer ferroelectric capacitors with solvent modified highly conducting polymeric poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) [PEDOT:PSS] electrodes on plastic substrates with performance as good as devices with metallic Platinum-Gold electrodes on silicon substrates; the first all-polymer high performance ferroelectric memory on banknotes for security applications; novel ferroelectric capacitors based on blends of ferroelectric poly(vinylidene fluoride

  6. Flexible spin-orbit torque devices

    Energy Technology Data Exchange (ETDEWEB)

    Lee, OukJae; You, Long; Jang, Jaewon; Subramanian, Vivek [Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720 (United States); Salahuddin, Sayeef [Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2015-12-21

    We report on state-of-the-art spintronic devices synthesized and fabricated directly on a flexible organic substrate. Large perpendicular magnetic anisotropy was achieved in ultrathin ferromagnetic heterostructures of Pt/Co/MgO sputtered on a non-rigid plastic substrate at room temperature. Subsequently, a full magnetic reversal of the Co was observed by exploiting the spin orbit coupling in Pt that leads to a spin accumulation at the Pt/Co interface when an in-plane current is applied. Quasi-static measurements show the potential for operating these devices at nano-second speeds. Importantly, the behavior of the devices remained unchanged under varying bending conditions (up to a bending radius of ≈ ±20–30 mm). Furthermore, the devices showed robust operation even after application of 10{sup 6} successive pulses, which is likely sufficient for many flexible applications. Thus, this work demonstrates the potential for integrating high performance spintronic devices on flexible substrates, which could lead to many applications ranging from flexible non-volatile magnetic memory to local magnetic resonance imaging.

  7. Flexible spintronic devices on Kapton

    DEFF Research Database (Denmark)

    Bedoya-Pinto, Amilcar; Donolato, Marco; Gobbi, Marco;

    2014-01-01

    of bending angle (r = 5 mm) have been achieved without degradation of the device performance, reaching room-temperature tunneling magnetoresistance ratios of 12% in bended Co/Al2O3/NiFe junctions. In addition, a suitable route to pattern high-quality nanostructures directly on the polyimide surface......Magnetic tunnel junctions and nano-sized domain-wall conduits have been fabricated on the flexible substrate Kapton. Despite the delicate nature of tunneling barriers and zig-zag shaped nanowires, the devices show an outstanding integrity and robustness upon mechanical bending. High values...... is established. These results demonstrate that Kapton is a promising platform for low-cost, flexible spintronic applications involving tunnel junction elements and nanostructurization. ...

  8. Graphene based flexible electrochromic devices.

    Science.gov (United States)

    Polat, Emre O; Balcı, Osman; Kocabas, Coskun

    2014-10-01

    Graphene emerges as a viable material for optoelectronics because of its broad optical response and gate-tunable properties. For practical applications, however, single layer graphene has performance limits due to its small optical absorption defined by fundamental constants. Here, we demonstrated a new class of flexible electrochromic devices using multilayer graphene (MLG) which simultaneously offers all key requirements for practical applications; high-contrast optical modulation over a broad spectrum, good electrical conductivity and mechanical flexibility. Our method relies on electro-modulation of interband transition of MLG via intercalation of ions into the graphene layers. The electrical and optical characterizations reveal the key features of the intercalation process which yields broadband optical modulation up to 55 per cent in the visible and near-infrared. We illustrate the promises of the method by fabricating reflective/transmissive electrochromic devices and multi-pixel display devices. Simplicity of the device architecture and its compatibility with the roll-to-roll fabrication processes, would find wide range of applications including smart windows and display devices. We anticipate that this work provides a significant step in realization of graphene based optoelectronics.

  9. Flexible one diode-one phase change memory array enabled by block copolymer self-assembly.

    Science.gov (United States)

    Mun, Beom Ho; You, Byoung Kuk; Yang, Se Ryeun; Yoo, Hyeon Gyun; Kim, Jong Min; Park, Woon Ik; Yin, You; Byun, Myunghwan; Jung, Yeon Sik; Lee, Keon Jae

    2015-04-28

    Flexible memory is the fundamental component for data processing, storage, and radio frequency communication in flexible electronic systems. Among several emerging memory technologies, phase-change random-access memory (PRAM) is one of the strongest candidate for next-generation nonvolatile memories due to its remarkable merits of large cycling endurance, high speed, and excellent scalability. Although there are a few approaches for flexible phase-change memory (PCM), high reset current is the biggest obstacle for the practical operation of flexible PCM devices. In this paper, we report a flexible PCM realized by incorporating nanoinsulators derived from a Si-containing block copolymer (BCP) to significantly lower the operating current of the flexible memory formed on plastic substrate. The reduction of thermal stress by BCP nanostructures enables the reliable operation of flexible PCM devices integrated with ultrathin flexible diodes during more than 100 switching cycles and 1000 bending cycles.

  10. Material challenge for flexible organic devices

    Directory of Open Access Journals (Sweden)

    Jay Lewis

    2006-04-01

    Full Text Available Outside of the active device layers, there are a variety of requisite functional layers in flexible organic electronic devices. Whether the application is in displays, lighting, integrated circuits, or photovoltaics, there are materials challenges in implementing flexible and/or organic devices into practical applications. We highlight two topics that are common to most flexible electronic technologies. First, we describe the difficulty in developing suitable permeation barriers on polymer substrates, the approaches being taken to solve this problem, and their current status. Second, we highlight the limited mechanical ruggedness of brittle inorganic films and present approaches for improving overall device flexibility.

  11. memCUDA: Map Device Memory to Host Memory on GPGPU Platform

    OpenAIRE

    Jin, Hai; Li, Bo; Zhang, Qin; Ao, Wenbing

    2010-01-01

    International audience; The Compute Unified Device Architecture (CUDA) programming environment from NVIDIA is a milestone towards making programming many-core GPUs more flexible to programmers. However, there are still many challenges for programmers when using CUDA. One is how to deal with GPU device memory, and data transfer between host memory and GPU device memory explicitly. In this study, source-to-source compiling and runtime library technologies are used to implement an experimental p...

  12. An optically transparent and flexible memory with embedded gold nanoparticles in a polymethylsilsesquioxane dielectric

    Energy Technology Data Exchange (ETDEWEB)

    Ooi, P.C. [Mechanical Engineering, The University of Auckland (New Zealand); Aw, K.C., E-mail: k.aw@auckland.ac.nz [Mechanical Engineering, The University of Auckland (New Zealand); Gao, W. [Chemical and Materials Engineering, The University of Auckland (New Zealand); Razak, K.A. [School of Materials and Mineral Resources Engineering, Universiti Sains (Malaysia); NanoBiotechnology Research and Innovation, INFORMM, Universiti Sains (Malaysia)

    2013-10-01

    In this work, we demonstrated a simple fabrication route towards an optically transparent and flexible memory device. The device is simple and consists of a metal/insulator/semiconductor structure; namely MIS. The preliminary MIS study with gold nanoparticles embedded between the polymethylsilsesquioxane layers was fabricated on p-Si substrate and the capacitance versus voltage measurements confirmed the charge trapped capability of the fabricated MIS memory device. Subsequently, an optically transparent and flexible MIS memory device made from indium–tin-oxide coated polyethylene terephthalate substrate and pentacene was used to replace the opaque p-Si substrate as the active layer. Current versus voltage (I–V) plot of the transparent and flexible device shows the presence of hysteresis. In an I–V plot, three distinct regions have been identified and the transport mechanisms are explained. The fabricated optically transparent and mechanically flexible MIS memory device can be programmed and erased multiple times, similar to a flash memory. Mechanical characterization to determine the robustness of the flexible memory device was also conducted but failed to establish any relationship in this preliminary work as the effect was random. Hence, more work is needed to understand the reliability of this device, especially when they are subjected to mechanical stress. - Highlights: ► An optically transparent and mechanically flexible memory is presented. ► Electrical characteristics show reprogrammable memory similar to flash memory. ► Transport mechanisms are proposed and explained. ► Mechanical bending tests are conducted.

  13. CMOS compatible generic batch process towards flexible memory on bulk monocrystalline silicon (100)

    KAUST Repository

    Ghoneim, Mohamed T.

    2014-12-01

    Today\\'s mainstream flexible electronics research is geared towards replacing silicon either totally, by having organic devices on organic substrates, or partially, by transferring inorganic devices onto organic substrates. In this work, we present a pragmatic approach combining the desired flexibility of organic substrates and the ultra-high integration density, inherent in silicon semiconductor industry, to transform bulk/inflexible silicon into an ultra-thin mono-crystalline fabric. We also show the effectiveness of this approach in achieving fully flexible electronic systems. Furthermore, we provide a progress report on fabricating various memory devices on flexible silicon fabric and insights for completely flexible memory modules on silicon fabric.

  14. Flexibility of Event Boundaries in Autobiographical Memory

    Science.gov (United States)

    Hohman, Timothy J.; Peynircioğlu, Zehra F.; Beason-Held, Lori L.

    2014-01-01

    Events have clear and consistent boundaries that are defined during perception in a manner that influences memory performance. The natural process of event segmentation shapes event definitions during perception, and appears to play a critical role in defining distinct episodic memories at encoding. However, the role of retrieval processes in modifying event definitions is not clear. We explored how such processes changed event boundary definitions at recall. In Experiment 1 we showed that distance from encoding is related to boundary flexibility. Participants were more likely to move self-reported event boundaries to include information reported beyond those boundaries when recalling more distant events compared to more recent events. In Experiment 2, we showed that age also influenced boundary flexibility. Older Age adults were more likely to move event boundaries than College Age adults, and the relationship between distance from encoding and boundary flexibility seen in Experiment 1 was present only in College Age and Middle Age adults. These results suggest that factors at retrieval have a direct impact on event definitions in memory and that, although episodic memories may be initially defined at encoding, these definitions are not necessarily maintained in long-term memory. PMID:22989194

  15. Review on Physically Flexible Nonvolatile Memory for Internet of Everything Electronics

    Directory of Open Access Journals (Sweden)

    Mohamed T. Ghoneim

    2015-07-01

    Full Text Available Solid-state memory is an essential component of the digital age. With advancements in healthcare technology and the Internet of Things (IoT, the demand for ultra-dense, ultra-low-power memory is increasing. In this review, we present a comprehensive perspective on the most notable approaches to the fabrication of physically flexible memory devices. With the future goal of replacing traditional mechanical hard disks with solid-state storage devices, a fully flexible electronic system will need two basic devices: transistors and nonvolatile memory. Transistors are used for logic operations and gating memory arrays, while nonvolatile memory (NVM devices are required for storing information in the main memory and cache storage. Since the highest density of transistors and storage structures is manifested in memories, the focus of this review is flexible NVM. Flexible NVM components are discussed in terms of their functionality, performance metrics, and reliability aspects, all of which are critical components for NVM technology to be part of mainstream consumer electronics, IoT, and advanced healthcare devices. Finally, flexible NVMs are benchmarked and future prospects are provided.

  16. Review on Physically Flexible Nonvolatile Memory for Internet of Everything Electronics

    KAUST Repository

    Ghoneim, Mohamed T.

    2015-07-23

    Solid-state memory is an essential component of the digital age. With advancements in healthcare technology and the Internet of Things (IoT), the demand for ultra-dense, ultra-low-power memory is increasing. In this review, we present a comprehensive perspective on the most notable approaches to the fabrication of physically flexible memory devices. With the future goal of replacing traditional mechanical hard disks with solid-state storage devices, a fully flexible electronic system will need two basic devices: transistors and nonvolatile memory. Transistors are used for logic operations and gating memory arrays, while nonvolatile memory (NVM) devices are required for storing information in the main memory and cache storage. Since the highest density of transistors and storage structures is manifested in memories, the focus of this review is flexible NVM. Flexible NVM components are discussed in terms of their functionality, performance metrics, and reliability aspects, all of which are critical components for NVM technology to be part of mainstream consumer electronics, IoT, and advanced healthcare devices. Finally, flexible NVMs are benchmarked and future prospects are provided.

  17. Movable MEMS Devices on Flexible Silicon

    KAUST Repository

    Ahmed, Sally

    2013-05-05

    Flexible electronics have gained great attention recently. Applications such as flexible displays, artificial skin and health monitoring devices are a few examples of this technology. Looking closely at the components of these devices, although MEMS actuators and sensors can play critical role to extend the application areas of flexible electronics, fabricating movable MEMS devices on flexible substrates is highly challenging. Therefore, this thesis reports a process for fabricating free standing and movable MEMS devices on flexible silicon substrates; MEMS flexure thermal actuators have been fabricated to illustrate the viability of the process. Flexure thermal actuators consist of two arms: a thin hot arm and a wide cold arm separated by a small air gap; the arms are anchored to the substrate from one end and connected to each other from the other end. The actuator design has been modified by adding etch holes in the anchors to suit the process of releasing a thin layer of silicon from the bulk silicon substrate. Selecting materials that are compatible with the release process was challenging. Moreover, difficulties were faced in the fabrication process development; for example, the structural layer of the devices was partially etched during silicon release although it was protected by aluminum oxide which is not attacked by the releasing gas . Furthermore, the thin arm of the thermal actuator was thinned during the fabrication process but optimizing the patterning and etching steps of the structural layer successfully solved this problem. Simulation was carried out to compare the performance of the original and the modified designs for the thermal actuators and to study stress and temperature distribution across a device. A fabricated thermal actuator with a 250 μm long hot arm and a 225 μm long cold arm separated by a 3 μm gap produced a deflection of 3 μm before silicon release, however, the fabrication process must be optimized to obtain fully functioning

  18. Silk Fibroin for Flexible Electronic Devices.

    Science.gov (United States)

    Zhu, Bowen; Wang, Hong; Leow, Wan Ru; Cai, Yurong; Loh, Xian Jun; Han, Ming-Yong; Chen, Xiaodong

    2016-06-01

    Flexible electronic devices are necessary for applications involving unconventional interfaces, such as soft and curved biological systems, in which traditional silicon-based electronics would confront a mechanical mismatch. Biological polymers offer new opportunities for flexible electronic devices by virtue of their biocompatibility, environmental benignity, and sustainability, as well as low cost. As an intriguing and abundant biomaterial, silk offers exquisite mechanical, optical, and electrical properties that are advantageous toward the development of next-generation biocompatible electronic devices. The utilization of silk fibroin is emphasized as both passive and active components in flexible electronic devices. The employment of biocompatible and biosustainable silk materials revolutionizes state-of-the-art electronic devices and systems that currently rely on conventional semiconductor technologies. Advances in silk-based electronic devices would open new avenues for employing biomaterials in the design and integration of high-performance biointegrated electronics for future applications in consumer electronics, computing technologies, and biomedical diagnosis, as well as human-machine interfaces.

  19. Organic nonvolatile memory devices based on ferroelectricity

    NARCIS (Netherlands)

    Naber, R.C.G.; Asadi, K.; Blom, P.W.M.; Leeuw, D.M. de; Boer, B. de

    2010-01-01

    A memory functionality is a prerequisite for many applications of electronic devices. Organic nonvolatile memory devices based on ferroelectricity are a promising approach toward the development of a low-cost memory technology. In this Review Article we discuss the latest developments in this area w

  20. Organic Nonvolatile Memory Devices Based on Ferroelectricity

    NARCIS (Netherlands)

    Naber, Ronald C. G.; Asadi, Kamal; Blom, Paul W. M.; de Leeuw, Dago M.; de Boer, Bert

    2010-01-01

    A memory functionality is a prerequisite for many applications of electronic devices. Organic nonvolatile memory devices based on ferroelectricity are a promising approach toward the development of a low-cost memory technology. In this Review Article we discuss the latest developments in this area w

  1. Memory devices based on organic electric bistable materials

    Institute of Scientific and Technical Information of China (English)

    CHEN Qi; BAI Hua; SHI GaoQuan

    2007-01-01

    Organic/metallic composites have demonstrated electrical bistability, as well as memory effects. These advanced materials have shown potential applications in digital information storage because of their good stability, flexibility and fast response speed. The electric bistability phenomenon can be explained by electric field-induced electron transfer/storage. This article reviews the recent progress of memory devices based on organic/metallic and polymeric composites with electric bistability.

  2. Organic memory device with polyaniline nanoparticles embedded as charging elements

    Science.gov (United States)

    Kim, Yo-Han; Kim, Minkeun; Oh, Sewook; Jung, Hunsang; Kim, Yejin; Yoon, Tae-Sik; Kim, Yong-Sang; Ho Lee, Hyun

    2012-04-01

    Polyaniline nanoparticles (PANI NPs) were synthesized and fabricated as charging elements for organic memory devices. The PANI NPs charging layer was self-assembled by epoxy-amine bonds between 3-glycidylpropyl trimethoxysilane functionalized dielectrics and PANI NPs. A memory window of 5.8 V (ΔVFB) represented by capacitance-voltage hysteresis was obtained for metal-pentacene-insulator-silicon capacitor. In addition, program/erase operations controlled by gate bias (-/+90 V) were demonstrated in the PANI NPs embedded pentacene thin film transistor device with polyvinylalcohol dielectric on flexible polyimide substrate. These results can be extended to development of fully organic-based electronic device.

  3. Flexible NAND-Like Organic Ferroelectric Memory Array

    NARCIS (Netherlands)

    Kam, B.; Ke, T.H.; Chasin, A.; Tyagi, M.; Cristoferi, C.; Tempelaars, K.; Breemen, A.J.J.M. van; Myny, K.; Schols, S.; Genoe, J.; Gelinck, G.H.; Heremans, P.

    2014-01-01

    We present a memory array of organic ferroelectric field-effect transistors (OFeFETs) on flexible substrates. The OFeFETs are connected serially, similar to the NAND architecture of flash memory, which offers the highest memory density of transistor memories. We demonstrate a reliable addressing sch

  4. Polymer and organic nonvolatile memory devices

    NARCIS (Netherlands)

    Heremans, P.; Gelinck, G.H.; Müller, R.; Baeg, K.J.; Kim, D.Y.; Noh, Y.Y.

    2011-01-01

    Organic molecules and semiconductors have been proposed as active part of a large variety of nonvolatile memory devices, including resistors, diodes and transistors. In this review, we focus on electrically reprogrammable nonvolatile memories. We classify several possible devices according to their

  5. High performance flexible electronics for biomedical devices.

    Science.gov (United States)

    Salvatore, Giovanni A; Munzenrieder, Niko; Zysset, Christoph; Kinkeldei, Thomas; Petti, Luisa; Troster, Gerhard

    2014-01-01

    Plastic electronics is soft, deformable and lightweight and it is suitable for the realization of devices which can form an intimate interface with the body, be implanted or integrated into textile for wearable and biomedical applications. Here, we present flexible electronics based on amorphous oxide semiconductors (a-IGZO) whose performance can achieve MHz frequency even when bent around hair. We developed an assembly technique to integrate complex electronic functionalities into textile while preserving the softness of the garment. All this and further developments can open up new opportunities in health monitoring, biotechnology and telemedicine.

  6. Dynamic neural systems enable adaptive, flexible memories.

    NARCIS (Netherlands)

    Kroes, M.C.W.; Fernandez, G.S.E.

    2012-01-01

    Almost all studies on memory formation have implicitly put forward a rather static view on memory. However, memories are not stable but sensitive to changes over time. Here we argue that memory alterations arise from the inherent predictive function of memory. Within this framework, we draw an

  7. Flexible heartbeat sensor for wearable device.

    Science.gov (United States)

    Kwak, Yeon Hwa; Kim, Wonhyo; Park, Kwang Bum; Kim, Kunnyun; Seo, Sungkyu

    2017-03-08

    We demonstrate a flexible strain-gauge sensor and its use in a wearable application for heart rate detection. This polymer-based strain-gauge sensor was fabricated using a double-sided fabrication method with polymer and metal, i.e., polyimide and nickel-chrome. The fabrication process for this strain-gauge sensor is compatible with the conventional flexible printed circuit board (FPCB) processes facilitating its commercialization. The fabricated sensor showed a linear relation for an applied normal force of more than 930 kPa, with a minimum detectable force of 6.25Pa. This sensor can also linearly detect a bending radius from 5mm to 100mm. It is a thin, flexible, compact, and inexpensive (for mass production) heart rate detection sensor that is highly sensitive compared to the established optical photoplethysmography (PPG) sensors. It can detect not only the timing of heart pulsation, but also the amplitude or shape of the pulse signal. The proposed strain-gauge sensor can be applicable to various applications for smart devices requiring heartbeat detection.

  8. Shape memory polymer medical device

    Science.gov (United States)

    Maitland, Duncan; Benett, William J.; Bearinger, Jane P.; Wilson, Thomas S.; Small, IV, Ward; Schumann, Daniel L.; Jensen, Wayne A.; Ortega, Jason M.; Marion, III, John E.; Loge, Jeffrey M.

    2010-06-29

    A system for removing matter from a conduit. The system includes the steps of passing a transport vehicle and a shape memory polymer material through the conduit, transmitting energy to the shape memory polymer material for moving the shape memory polymer material from a first shape to a second and different shape, and withdrawing the transport vehicle and the shape memory polymer material through the conduit carrying the matter.

  9. Projected phase-change memory devices

    Science.gov (United States)

    Koelmans, Wabe W.; Sebastian, Abu; Jonnalagadda, Vara Prasad; Krebs, Daniel; Dellmann, Laurent; Eleftheriou, Evangelos

    2015-09-01

    Nanoscale memory devices, whose resistance depends on the history of the electric signals applied, could become critical building blocks in new computing paradigms, such as brain-inspired computing and memcomputing. However, there are key challenges to overcome, such as the high programming power required, noise and resistance drift. Here, to address these, we present the concept of a projected memory device, whose distinguishing feature is that the physical mechanism of resistance storage is decoupled from the information-retrieval process. We designed and fabricated projected memory devices based on the phase-change storage mechanism and convincingly demonstrate the concept through detailed experimentation, supported by extensive modelling and finite-element simulations. The projected memory devices exhibit remarkably low drift and excellent noise performance. We also demonstrate active control and customization of the programming characteristics of the device that reliably realize a multitude of resistance states.

  10. Flexibility of representational states in working memory

    Directory of Open Access Journals (Sweden)

    Nahid eZokaei

    2014-11-01

    Full Text Available The relationship between working memory (WM and attention is a highly interdependent one, with evidence that attention determines the state in which items in WM are retained. Through focusing of attention, an item might be held in a more prioritized state, commonly termed as the focus of attention (FOA. The remaining items, although still retrievable, are considered to be in a different representational state. One means to bring an item into the FOA is to use retrospective cues (‘retro-cues’ which direct attention to one of the objects retained in WM. Alternatively, an item can enter a privileged state once attention is directed towards it through bottom-up influences (e.g. recency effect or by performing an action on one of the retained items (‘incidental’ cueing. In all these cases, the item in the FOA is recalled with better accuracy compared to the other items in WM. Far less is known about the nature of the other items in WM and whether they can be flexibly manipulated in and out of the FOA. We present data from three types of experiments as well as transcranial magnetic stimulation to early visual cortex to manipulate the item inside FOA. Taken together, our results suggest that the context in which items are retained in WM matters. When an item remains behaviourally relevant, despite not being inside the FOA, re-focusing attention upon it can increase its recall precision. This suggests that a non-FOA item can be held in a state in which it can be later retrieved. However, if an item is rendered behaviourally unimportant because it is very unlikely to be probed, it cannot be brought back into the FOA, nor recalled with high precision. Under such conditions, some information appears to be irretrievably lost from WM. These findings, obtained from several different methods, demonstrate quite considerable flexibility with which items in WM can be represented depending upon context. They have important consequences for emerging state

  11. Rapid formation and flexible expressionof memories of subliminal word pairs

    Directory of Open Access Journals (Sweden)

    Thomas Peter Reber

    2011-11-01

    Full Text Available Our daily experiences are incidentally and rapidly encoded as episodic memories. Episodic memories consist of numerous associations (e.g., who gave what to whom where and when that can be expressed flexibly in new situations. Key features of episodic memory are speed of encoding, its associative nature, and its representational flexibility. Another defining feature of human episodic memory has been consciousness of encoding/retrieval. Here, we show that humans can rapidly form associations between subliminal words and minutes later retrieve these associations even if retrieval words were conceptually related to, but different from encoding words. Because encoding words were presented subliminally, associative encoding and retrieval were unconscious. Unconscious association formation and retrieval were dependent on a preceding understanding of task principles. We conclude that key computations underlying episodic memory – rapid encoding and flexible expression of associations - can operate outside consciousness.

  12. Flexible energy-storage devices: design consideration and recent progress.

    Science.gov (United States)

    Wang, Xianfu; Lu, Xihong; Liu, Bin; Chen, Di; Tong, Yexiang; Shen, Guozhen

    2014-07-23

    Flexible energy-storage devices are attracting increasing attention as they show unique promising advantages, such as flexibility, shape diversity, light weight, and so on; these properties enable applications in portable, flexible, and even wearable electronic devices, including soft electronic products, roll-up displays, and wearable devices. Consequently, considerable effort has been made in recent years to fulfill the requirements of future flexible energy-storage devices, and much progress has been witnessed. This review describes the most recent advances in flexible energy-storage devices, including flexible lithium-ion batteries and flexible supercapacitors. The latest successful examples in flexible lithium-ion batteries and their technological innovations and challenges are reviewed first. This is followed by a detailed overview of the recent progress in flexible supercapacitors based on carbon materials and a number of composites and flexible micro-supercapacitors. Some of the latest achievements regarding interesting integrated energy-storage systems are also reviewed. Further research direction is also proposed to surpass existing technological bottle-necks and realize idealized flexible energy-storage devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Resistive switching of Pt/TiO x /Pt devices fabricated on flexible Parylene-C substrates

    Science.gov (United States)

    Khiat, Ali; Cortese, Simone; Serb, Alexander; Prodromakis, Themistoklis

    2017-01-01

    Pt/TiO x /Pt resistive switching (RS) devices are considered to be amongst the most promising candidates in memristor family and the technology transfer to flexible substrates could open the way to new opportunities for flexible memory implementations. Hence, an important goal is to achieve a fully flexible RS memory technology. Nonetheless, several fabrication challenges are present and must be solved prior to achieving reliable device fabrication and good electronic performances. Here, we propose a fabrication method for the successful transfer of Pt/TiO x /Pt stack onto flexible Parylene-C substrates. The devices were electrically characterised, exhibiting both digital and analogue memory characteristics, which are obtained by proper adjustment of pulsing schemes during tests. This approach could open new application possibilities of these devices in neuromorphic computing, data processing, implantable sensors and bio-compatible neural interfaces.

  14. Towards Flexibility Detection in Device-Level Energy Consumption

    DEFF Research Database (Denmark)

    Neupane, Bijay; Pedersen, Torben Bach; Thiesson, Bo

    2014-01-01

    The increasing drive towards green energy has boosted the installation of Renewable Energy Sources (RES). Increasing the share of RES in the power grid requires demand management by flexibility in the consumption. In this paper, we perform a state-of-the-art analysis on the flexibility...... regularities and patterns and the correlation between operating different devices. Subsequently, we show the existence of detectable time and energy flexibility in device operations. Finally, we provide various results providing a foundation for load- and flexibility-detection and -prediction at the device...

  15. Towards Flexibility Detection in Device-Level Energy Consumption

    DEFF Research Database (Denmark)

    Neupane, Bijay; Pedersen, Torben Bach; Thiesson, Bo

    2014-01-01

    The increasing drive towards green energy has boosted the installation of Renewable Energy Sources (RES). Increasing the share of RES in the power grid requires demand management by flexibility in the consumption. In this paper, we perform a state-of-the-art analysis on the flexibility...... regularities and patterns and the correlation between operating different devices. Subsequently, we show the existence of detectable time and energy flexibility in device operations. Finally, we provide various results providing a foundation for load- and flexibility-detection and -prediction at the device...

  16. Combating Memory Corruption Attacks On Scada Devices

    Science.gov (United States)

    Bellettini, Carlo; Rrushi, Julian

    Memory corruption attacks on SCADA devices can cause significant disruptions to control systems and the industrial processes they operate. However, despite the presence of numerous memory corruption vulnerabilities, few, if any, techniques have been proposed for addressing the vulnerabilities or for combating memory corruption attacks. This paper describes a technique for defending against memory corruption attacks by enforcing logical boundaries between potentially hostile data and safe data in protected processes. The technique encrypts all input data using random keys; the encrypted data is stored in main memory and is decrypted according to the principle of least privilege just before it is processed by the CPU. The defensive technique affects the precision with which attackers can corrupt control data and pure data, protecting against code injection and arc injection attacks, and alleviating problems posed by the incomparability of mitigation techniques. An experimental evaluation involving the popular Modbus protocol demonstrates the feasibility and efficiency of the defensive technique.

  17. Resistively heated shape memory polymer device

    Energy Technology Data Exchange (ETDEWEB)

    Marion, III, John E.; Bearinger, Jane P.; Wilson, Thomas S.; Maitland, Duncan J.

    2017-09-05

    A resistively heated shape memory polymer device is made by providing a rod, sheet or substrate that includes a resistive medium. The rod, sheet or substrate is coated with a first shape memory polymer providing a coated intermediate unit. The coated intermediate unit is in turn coated with a conductive material providing a second intermediate unit. The second coated intermediate unit is in turn coated with an outer shape memory polymer. The rod, sheet or substrate is exposed and an electrical lead is attached to the rod, sheet or substrate. The conductive material is exposed and an electrical lead is attached to the conductive material.

  18. Resistively heated shape memory polymer device

    Science.gov (United States)

    Marion, III, John E.; Bearinger, Jane P.; Wilson, Thomas S.; Maitland, Duncan J.

    2016-10-25

    A resistively heated shape memory polymer device is made by providing a rod, sheet or substrate that includes a resistive medium. The rod, sheet or substrate is coated with a first shape memory polymer providing a coated intermediate unit. The coated intermediate unit is in turn coated with a conductive material providing a second intermediate unit. The second coated intermediate unit is in turn coated with an outer shape memory polymer. The rod, sheet or substrate is exposed and an electrical lead is attached to the rod, sheet or substrate. The conductive material is exposed and an electrical lead is attached to the conductive material.

  19. Flexible Organic Electronics in Biology: Materials and Devices.

    Science.gov (United States)

    Liao, Caizhi; Zhang, Meng; Yao, Mei Yu; Hua, Tao; Li, Li; Yan, Feng

    2015-12-09

    At the convergence of organic electronics and biology, organic bioelectronics attracts great scientific interest. The potential applications of organic semiconductors to reversibly transmit biological signals or stimulate biological tissues inspires many research groups to explore the use of organic electronics in biological systems. Considering the surfaces of movable living tissues being arbitrarily curved at physiological environments, the flexibility of organic bioelectronic devices is of paramount importance in enabling stable and reliable performances by improving the contact and interaction of the devices with biological systems. Significant advances in flexible organic bio-electronics have been achieved in the areas of flexible organic thin film transistors (OTFTs), polymer electrodes, smart textiles, organic electrochemical ion pumps (OEIPs), ion bipolar junction transistors (IBJTs) and chemiresistors. This review will firstly discuss the materials used in flexible organic bioelectronics, which is followed by an overview on various types of flexible organic bioelectronic devices. The versatility of flexible organic bioelectronics promises a bright future for this emerging area.

  20. Transparent resistive switching memory using aluminum oxide on a flexible substrate

    Science.gov (United States)

    Yeom, Seung-Won; Shin, Sang-Chul; Kim, Tan-Young; Ha, Hyeon Jun; Lee, Yun-Hi; Shim, Jae Won; Ju, Byeong-Kwon

    2016-02-01

    Resistive switching memory (ReRAM) has attracted much attention in recent times owing to its fast switching, simple structure, and non-volatility. Flexible and transparent electronic devices have also attracted considerable attention. We therefore fabricated an Al2O3-based ReRAM with transparent indium-zinc-oxide (IZO) electrodes on a flexible substrate. The device transmittance was found to be higher than 80% in the visible region (400-800 nm). Bended states (radius = 10 mm) of the device also did not affect the memory performance because of the flexibility of the two transparent IZO electrodes and the thin Al2O3 layer. The conduction mechanism of the resistive switching of our device was explained by ohmic conduction and a Poole-Frenkel emission model. The conduction mechanism was proved by oxygen vacancies in the Al2O3 layer, as analyzed by x-ray photoelectron spectroscopy analysis. These results encourage the application of ReRAM in flexible and transparent electronic devices.

  1. Solid-state Memory on Flexible Silicon for Future Electronic Applications

    KAUST Repository

    Ghoneim, Mohamed

    2016-11-01

    Advancements in electronics research triggered a vision of a more connected world, touching new unprecedented fields to improve the quality of our lives. This vision has been fueled by electronic giants showcasing flexible displays for the first time in consumer electronics symposiums. Since then, the scientific and research communities partook on exploring possibilities for making flexible electronics. Decades of research have revealed many routes to flexible electronics, lots of opportunities and challenges. In this work, we focus on our contributions towards realizing a complimentary approach to flexible inorganic high performance electronic memories on silicon. This approach provides a straight forward method for capitalizing on the existing well-established semiconductor infrastructure, standard processes and procedures, and collective knowledge. Ultimately, we focus on understanding the reliability and functionality anomalies in flexible electronics and flexible solid state memory built using the flexible silicon platform. The results of the presented studies show that: (i) flexible devices fabricated using etch-protect-release approach (with trenches included in the active area) exhibit ~19% lower safe operating voltage compared to their bulk counterparts, (ii) they can withstand prolonged bending duration (static stress) but are prone to failure under dynamic stress as in repeated bending and re-flattening, (iii) flexible 3D FinFETs exhibit ~10% variation in key properties when exposed to out-of-plane bending stress and out-of-plane stress does not resemble the well-studied in-plane stress used in strain engineering, (iv) resistive memories can be achieved on flexible silicon and their basic resistive property is preserved but other memory functionalities (retention, endurance, speed, memory window) requires further investigations, (v) flexible silicon based PZT ferroelectric capacitors exhibit record polarization, capacitance, and endurance (1 billion

  2. Flexible and Stretchable Optoelectronic Devices using Silver Nanowires and Graphene.

    Science.gov (United States)

    Lee, Hanleem; Kim, Meeree; Kim, Ikjoon; Lee, Hyoyoung

    2016-06-01

    Many studies have accompanied the emergence of a great interest in flexible or/and stretchable devices for new applications in wearable and futuristic technology, including human-interface devices, robotic skin, and biometric devices, and in optoelectronic devices. Especially, new nanodimensional materials enable flexibility or stretchability to be brought based on their dimensionality. Here, the emerging field of flexible devices is briefly introduced using silver nanowires and graphene, which are famous nanomaterials for the use of transparent conductive electrodes, as examples, and their unique functions originating from the intrinsic property of these nanomaterials are highlighted. It is thought that this work will evoke more interest and idea exchanges in this emerging field and hopefully can trigger a breakthrough on a new type of optoelectronics and optogenetic devices in the near future. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Toward flexible polymer and paper-based energy storage devices.

    Science.gov (United States)

    Nyholm, Leif; Nyström, Gustav; Mihranyan, Albert; Strømme, Maria

    2011-09-01

    All-polymer and paper-based energy storage devices have significant inherent advantages in comparison with many currently employed batteries and supercapacitors regarding environmental friendliness, flexibility, cost and versatility. The research within this field is currently undergoing an exciting development as new polymers, composites and paper-based devices are being developed. In this report, we review recent progress concerning the development of flexible energy storage devices based on electronically conducting polymers and cellulose containing composites with particular emphasis on paper-based batteries and supercapacitors. We discuss recent progress in the development of the most commonly used electronically conducting polymers used in flexible device prototypes, the advantages and disadvantages of this type of energy storage devices, as well as the two main approaches used in the manufacturing of paper-based charge storage devices.

  4. Control devices incorporated with shape memory alloy

    Institute of Scientific and Technical Information of China (English)

    Xue Suduo; Li Xiongyan

    2007-01-01

    Shape Memory Alloy (SMA) is a type of material that offers some unique characteristics for use in devices for vibration control applications. Based on SMA's material properties, four types of control devices that incorporate NiTi SMA wires are introduced in this paper, which include three types of dampers (SMA damper, SMA-MR damper and SMA-friction damper) and one kind of isolation bearing (SMA-rubber bearing). Mechanical models of these devices and their experimental verifications are presented. To investigate the control performance of these devices, the SMA-MR damper and SMA-rubber bearing are applied to structures. The results show that the control devices could be effective in reducing the seismic response of structures.

  5. Shape Memory Polymer Therapeutic Devices for Stroke

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, T S; Small IV, W; Benett, W J; Bearinger, J P; Maitland, D J

    2005-10-11

    Shape memory polymers (SMPs) are attracting a great deal of interest in the scientific community for their use in applications ranging from light weight structures in space to micro-actuators in MEMS devices. These relatively new materials can be formed into a primary shape, reformed into a stable secondary shape, and then controllably actuated to recover their primary shape. The first part of this presentation will be a brief review of the types of polymeric structures which give rise to shape memory behavior in the context of new shape memory polymers with highly regular network structures recently developed at LLNL for biomedical devices. These new urethane SMPs have improved optical and physical properties relative to commercial SMPs, including improved clarity, high actuation force, and sharper actuation transition. In the second part of the presentation we discuss the development of SMP based devices for mechanically removing neurovascular occlusions which result in ischemic stroke. These devices are delivered to the site of the occlusion in compressed form, are pushed through the occlusion, actuated (usually optically) to take on an expanded conformation, and then used to dislodge and grip the thrombus while it is withdrawn through the catheter.

  6. Flexible Exchange of Farming Device Data

    DEFF Research Database (Denmark)

    Iftikhar, Nadeem; Pedersen, Torben Bach

    2011-01-01

    A new trend in the farming business is to replace conventional farming devices with computerized farming devices. Accordingly, numerous computer-based farming devices for logging, processing and exchanging data have recently been installed on moving farm machinery such as tractors. The exchange...... of data generally takes place between the devices and farming systems, mostly installed at the premises of farmers, contractors, advisory services etc. In most cases, data exchange is based on farming data exchange standards and is bi-directional. Bi-directional data exchange allows different devices...... and systems to exchange data based on a predefined set of rules. In consequence, many hand-coded data exchange solutions have been developed in the farming business. Although efforts regarding incorporating data exchange standards have been made, their actual usage so far has been limited, due to the fact...

  7. Large-area, flexible imaging arrays constructed by light-charge organic memories

    OpenAIRE

    Lei Zhang; Ti Wu; Yunlong Guo; Yan Zhao; Xiangnan Sun; Yugeng Wen; Gui Yu; Yunqi Liu

    2013-01-01

    Existing organic imaging circuits, which offer attractive benefits of light weight, low cost and flexibility, are exclusively based on phototransistor or photodiode arrays. One shortcoming of these photo-sensors is that the light signal should keep invariant throughout the whole pixel-addressing and reading process. As a feasible solution, we synthesized a new charge storage molecule and embedded it into a device, which we call light-charge organic memory (LCOM). In LCOM, the functionalities ...

  8. Study of harsh environment operation of flexible ferroelectric memory integrated with PZT and silicon fabric

    KAUST Repository

    Ghoneim, Mohamed T.

    2015-08-05

    Flexible memory can enable industrial, automobile, space, and smart grid centered harsh/extreme environment focused electronics application(s) for enhanced operation, safety, and monitoring where bent or complex shaped infrastructures are common and state-of-the-art rigid electronics cannot be deployed. Therefore, we report on the physical-mechanical-electrical characteristics of a flexible ferroelectric memory based on lead zirconium titanate as a key memory material and flexible version of bulk mono-crystalline silicon (100). The experimented devices show a bending radius down to 1.25 cm corresponding to 0.16% nominal strain (high pressure of ∼260 MPa), and full functionality up to 225 °C high temperature in ambient gas composition (21% oxygen and 55% relative humidity). The devices showed unaltered data retention and fatigue properties under harsh conditions, still the reduced memory window (20% difference between switching and non-switching currents at 225 °C) requires sensitive sense circuitry for proper functionality and is the limiting factor preventing operation at higher temperatures.

  9. Multilevel Ultrafast Flexible Nanoscale Nonvolatile Hybrid Graphene Oxide-Titanium Oxide Memories.

    Science.gov (United States)

    Nagareddy, V Karthik; Barnes, Matthew D; Zipoli, Federico; Lai, Khue T; Alexeev, Arseny M; Craciun, Monica Felicia; Wright, C David

    2017-02-27

    Graphene oxide (GO) resistive memories offer the promise of low-cost environmentally sustainable fabrication, high mechanical flexibility and high optical transparency, making them ideally suited to future flexible and transparent electronics applications. However, the dimensional and temporal scalability of GO memories, i.e., how small they can be made and how fast they can be switched, is an area that has received scant attention. Moreover, a plethora of GO resistive switching characteristics and mechanisms has been reported in the literature, sometimes leading to a confusing and conflicting picture. Consequently, the potential for graphene oxide to deliver high-performance memories operating on nanometer length and nanosecond time scales is currently unknown. Here we address such shortcomings, presenting not only the smallest (50 nm), fastest (sub-5 ns), thinnest (8 nm) GO-based memory devices produced to date, but also demonstrate that our approach provides easily accessible multilevel (4-level, 2-bit per cell) storage capabilities along with excellent endurance and retention performance-all on both rigid and flexible substrates. Via comprehensive experimental characterizations backed-up by detailed atomistic simulations, we also show that the resistive switching mechanism in our Pt/GO/Ti/Pt devices is driven by redox reactions in the interfacial region between the top (Ti) electrode and the GO layer.

  10. Study of harsh environment operation of flexible ferroelectric memory integrated with PZT and silicon fabric

    Science.gov (United States)

    Ghoneim, M. T.; Hussain, M. M.

    2015-08-01

    Flexible memory can enable industrial, automobile, space, and smart grid centered harsh/extreme environment focused electronics application(s) for enhanced operation, safety, and monitoring where bent or complex shaped infrastructures are common and state-of-the-art rigid electronics cannot be deployed. Therefore, we report on the physical-mechanical-electrical characteristics of a flexible ferroelectric memory based on lead zirconium titanate as a key memory material and flexible version of bulk mono-crystalline silicon (100). The experimented devices show a bending radius down to 1.25 cm corresponding to 0.16% nominal strain (high pressure of ˜260 MPa), and full functionality up to 225 °C high temperature in ambient gas composition (21% oxygen and 55% relative humidity). The devices showed unaltered data retention and fatigue properties under harsh conditions, still the reduced memory window (20% difference between switching and non-switching currents at 225 °C) requires sensitive sense circuitry for proper functionality and is the limiting factor preventing operation at higher temperatures.

  11. Flexible manufacturing for photonics device assembly

    Science.gov (United States)

    Lu, Shin-Yee; Pocha, Michael D.; Strand, Oliver T.; Young, K. David

    1994-01-01

    The assembly of photonics devices such as laser diodes, optical modulators, and opto-electronics multi-chip modules (OEMCM), usually requires the placement of micron size devices such as laser diodes, and sub-micron precision attachment between optical fibers and diodes or waveguide modulators (usually referred to as pigtailing). This is a very labor intensive process. Studies done by the opto-electronics (OE) industry have shown that 95 percent of the cost of a pigtailed photonic device is due to the use of manual alignment and bonding techniques, which is the current practice in industry. At Lawrence Livermore National Laboratory, we are working to reduce the cost of packaging OE devices through the use of automation. Our efforts are concentrated on several areas that are directly related to an automated process. This paper will focus on our progress in two of those areas, in particular, an automated fiber pigtailing machine and silicon micro-technology compatible with an automated process.

  12. Paper‐Based Electrodes for Flexible Energy Storage Devices

    Science.gov (United States)

    Yao, Bin; Zhang, Jing; Kou, Tianyi; Song, Yu; Liu, Tianyu

    2017-01-01

    Paper‐based materials are emerging as a new category of advanced electrodes for flexible energy storage devices, including supercapacitors, Li‐ion batteries, Li‐S batteries, Li‐oxygen batteries. This review summarizes recent advances in the synthesis of paper‐based electrodes, including paper‐supported electrodes and paper‐like electrodes. Their structural features, electrochemical performances and implementation as electrodes for flexible energy storage devices including supercapacitors and batteries are highlighted and compared. Finally, we also discuss the challenges and opportunity of paper‐based electrodes and energy storage devices. PMID:28725532

  13. Status and Prospects of ZnO-Based Resistive Switching Memory Devices.

    Science.gov (United States)

    Simanjuntak, Firman Mangasa; Panda, Debashis; Wei, Kung-Hwa; Tseng, Tseung-Yuen

    2016-12-01

    In the advancement of the semiconductor device technology, ZnO could be a prospective alternative than the other metal oxides for its versatility and huge applications in different aspects. In this review, a thorough overview on ZnO for the application of resistive switching memory (RRAM) devices has been conducted. Various efforts that have been made to investigate and modulate the switching characteristics of ZnO-based switching memory devices are discussed. The use of ZnO layer in different structure, the different types of filament formation, and the different types of switching including complementary switching are reported. By considering the huge interest of transparent devices, this review gives the concrete overview of the present status and prospects of transparent RRAM devices based on ZnO. ZnO-based RRAM can be used for flexible memory devices, which is also covered here. Another challenge in ZnO-based RRAM is that the realization of ultra-thin and low power devices. Nevertheless, ZnO not only offers decent memory properties but also has a unique potential to be used as multifunctional nonvolatile memory devices. The impact of electrode materials, metal doping, stack structures, transparency, and flexibility on resistive switching properties and switching parameters of ZnO-based resistive switching memory devices are briefly compared. This review also covers the different nanostructured-based emerging resistive switching memory devices for low power scalable devices. It may give a valuable insight on developing ZnO-based RRAM and also should encourage researchers to overcome the challenges.

  14. Status and Prospects of ZnO-Based Resistive Switching Memory Devices

    Science.gov (United States)

    Simanjuntak, Firman Mangasa; Panda, Debashis; Wei, Kung-Hwa; Tseng, Tseung-Yuen

    2016-08-01

    In the advancement of the semiconductor device technology, ZnO could be a prospective alternative than the other metal oxides for its versatility and huge applications in different aspects. In this review, a thorough overview on ZnO for the application of resistive switching memory (RRAM) devices has been conducted. Various efforts that have been made to investigate and modulate the switching characteristics of ZnO-based switching memory devices are discussed. The use of ZnO layer in different structure, the different types of filament formation, and the different types of switching including complementary switching are reported. By considering the huge interest of transparent devices, this review gives the concrete overview of the present status and prospects of transparent RRAM devices based on ZnO. ZnO-based RRAM can be used for flexible memory devices, which is also covered here. Another challenge in ZnO-based RRAM is that the realization of ultra-thin and low power devices. Nevertheless, ZnO not only offers decent memory properties but also has a unique potential to be used as multifunctional nonvolatile memory devices. The impact of electrode materials, metal doping, stack structures, transparency, and flexibility on resistive switching properties and switching parameters of ZnO-based resistive switching memory devices are briefly compared. This review also covers the different nanostructured-based emerging resistive switching memory devices for low power scalable devices. It may give a valuable insight on developing ZnO-based RRAM and also should encourage researchers to overcome the challenges.

  15. Transparent bipolar resistive switching memory on a flexible substrate with indium-zinc-oxide electrodes

    Science.gov (United States)

    Yeom, Seung-Won; Ha, Hyeon Jun; Park, Junsu; Shim, Jae Won; Ju, Byeong-Kwon

    2016-12-01

    We fabricated transparent indium zinc oxide (IZO)/TiO2/IZO devices on flexible polyethylene phthalate (PET) substrates. These devices demonstrate bipolar resistive switching behavior, exhibit a transmittance greater than 80 % for visible light, and have stable resistive switching properties, including long retention and good endurance. In addition, the devices were investigated based on their temperature dependence; the results show metallic properties in the low-resistance state (LRS) and semiconducting properties in the high-resistance state (HRS). The conduction mechanism for resistive switching in our device was well-fitted with Ohmic conduction in the LRS and Poole-Frenkel emission in the HRS. The mechanism could be explained by the formation and the rupture of the conduction paths formed by the movement of oxygen ions and vacancies. Moreover, acute bending of the devices did not affect the memory characteristics because of the pliability of both the IZO electrodes and the thin oxide layer. These results indicate potential applications as resistive random access memories in future flexible, transparent electronic devices.

  16. Monitoring of Vital Signs with Flexible and Wearable Medical Devices.

    Science.gov (United States)

    Khan, Yasser; Ostfeld, Aminy E; Lochner, Claire M; Pierre, Adrien; Arias, Ana C

    2016-06-01

    Advances in wireless technologies, low-power electronics, the internet of things, and in the domain of connected health are driving innovations in wearable medical devices at a tremendous pace. Wearable sensor systems composed of flexible and stretchable materials have the potential to better interface to the human skin, whereas silicon-based electronics are extremely efficient in sensor data processing and transmission. Therefore, flexible and stretchable sensors combined with low-power silicon-based electronics are a viable and efficient approach for medical monitoring. Flexible medical devices designed for monitoring human vital signs, such as body temperature, heart rate, respiration rate, blood pressure, pulse oxygenation, and blood glucose have applications in both fitness monitoring and medical diagnostics. As a review of the latest development in flexible and wearable human vitals sensors, the essential components required for vitals sensors are outlined and discussed here, including the reported sensor systems, sensing mechanisms, sensor fabrication, power, and data processing requirements.

  17. Flexible Robotic Spine Actuated by Shape Memory Alloy

    OpenAIRE

    2014-01-01

    A flexible robotic spine actuated by shape memory alloy (SMA) can achieve both bending motion and impact absorption, which will allow robots to realize a variety of postures. In this paper, the robotic spine is designed and simplified into a multi-segment dynamic model based on several verified assumptions. The SMA wire is modelled using the Seelecke-Muller-Acenbach theory. An iterative algorithm is developed to address the external forces distributed along the spine and compute the spine’s b...

  18. Flexible Multistate Data Storage Devices Fabricated Using Natural Lignin at Room Temperature.

    Science.gov (United States)

    Park, Youngjun; Lee, Jang-Sik

    2017-02-22

    The growing interest in bioinspired and sustainable electronics has induced research on biocompatible and biodegradable materials. However, conventional electronic devices have been restricted due to their nonbiodegradable and sometimes harmful and toxic materials, which can even cause environmental issues. Here, we report a resistive switching random access memory (ReRAM) device based on lignin, which is a biodegradable waste product of the paper industry. The active layer of the device can be easily formed using a simple solution process on a plastic substrate. The memory devices show stable bipolar resistive switching behavior with good endurance and retention. Appropriate control of the maximum reset voltage and compliance current can yield multibit data storage capability with at least four resistance states, which can be exploited to realize a high-density memory device. The resistive switching mechanism may be a result of formation and rupture of carbon-rich filaments. These results suggest that lignin is a promising candidate material for an inexpensive and environmentally benign ReRAM device. We believe that this study can initiate a new route toward development of biocompatible and flexible electronics.

  19. Memory and Spin Injection Devices Involving Half Metals

    Directory of Open Access Journals (Sweden)

    M. Shaughnessy

    2011-01-01

    Full Text Available We suggest memory and spin injection devices fabricated with half-metallic materials and based on the anomalous Hall effect. Schematic diagrams of the memory chips, in thin film and bulk crystal form, are presented. Spin injection devices made in thin film form are also suggested. These devices do not need any external magnetic field but make use of their own magnetization. Only a gate voltage is needed. The carriers are 100% spin polarized. Memory devices may potentially be smaller, faster, and less volatile than existing ones, and the injection devices may be much smaller and more efficient than existing spin injection devices.

  20. Flexible retrieval: When true inferences produce false memories.

    Science.gov (United States)

    Carpenter, Alexis C; Schacter, Daniel L

    2017-03-01

    Episodic memory involves flexible retrieval processes that allow us to link together distinct episodes, make novel inferences across overlapping events, and recombine elements of past experiences when imagining future events. However, the same flexible retrieval and recombination processes that underpin these adaptive functions may also leave memory prone to error or distortion, such as source misattributions in which details of one event are mistakenly attributed to another related event. To determine whether the same recombination-related retrieval mechanism supports both successful inference and source memory errors, we developed a modified version of an associative inference paradigm in which participants encoded everyday scenes comprised of people, objects, and other contextual details. These scenes contained overlapping elements (AB, BC) that could later be linked to support novel inferential retrieval regarding elements that had not appeared together previously (AC). Our critical experimental manipulation concerned whether contextual details were probed before or after the associative inference test, thereby allowing us to assess whether (a) false memories increased for successful versus unsuccessful inferences, and (b) any such effects were specific to after compared with before participants received the inference test. In each of 4 experiments that used variants of this paradigm, participants were more susceptible to false memories for contextual details after successful than unsuccessful inferential retrieval, but only when contextual details were probed after the associative inference test. These results suggest that the retrieval-mediated recombination mechanism that underlies associative inference also contributes to source misattributions that result from combining elements of distinct episodes. (PsycINFO Database Record

  1. Microwave impedance imaging on semiconductor memory devices

    Science.gov (United States)

    Kundhikanjana, Worasom; Lai, Keji; Yang, Yongliang; Kelly, Michael; Shen, Zhi-Xun

    2011-03-01

    Microwave impedance microscopy (MIM) maps out the real and imaginary components of the tip-sample impedance, from which the local conductivity and dielectric constant distribution can be derived. The stray field contribution is minimized in our shielded cantilever design, enabling quantitative analysis of nano-materials and device structures. We demonstrate here that the MIM can spatially resolve the conductivity variation in a dynamic random access memory (DRAM) sample. With DC or low-frequency AC bias applied to the tip, contrast between n-doped and p-doped regions in the dC/dV images is observed, and p-n junctions are highlighted in the dR/dV images. The results can be directly compared with data taken by scanning capacitance microscope (SCM), which uses unshielded cantilevers and resonant electronics, and the MIM reveals more information of the local dopant concentration than SCM.

  2. Nonvolatile multilevel data storage memory device from controlled ambipolar charge trapping mechanism

    Science.gov (United States)

    Zhou, Ye; Han, Su-Ting; Sonar, Prashant; Roy, V. A. L.

    2013-07-01

    The capability of storing multi-bit information is one of the most important challenges in memory technologies. An ambipolar polymer which intrinsically has the ability to transport electrons and holes as a semiconducting layer provides an opportunity for the charge trapping layer to trap both electrons and holes efficiently. Here, we achieved large memory window and distinct multilevel data storage by utilizing the phenomena of ambipolar charge trapping mechanism. As fabricated flexible memory devices display five well-defined data levels with good endurance and retention properties showing potential application in printed electronics.

  3. Polymer ferroelectric field-effect memory device with SnO channel layer exhibits record hole mobility

    KAUST Repository

    Caraveo-Frescas, J. A.

    2014-06-10

    Here we report for the first time a hybrid p-channel polymer ferroelectric field-effect transistor memory device with record mobility. The memory device, fabricated at 200C on both plastic polyimide and glass substrates, uses ferroelectric polymer P(VDF-TrFE) as the gate dielectric and transparent p-type oxide (SnO) as the active channel layer. A record mobility of 3.3 cm 2V-1s-1, large memory window (~16 V), low read voltages (~-1 V), and excellent retention characteristics up to 5000 sec have been achieved. The mobility achieved in our devices is over 10 times higher than previously reported polymer ferroelectric field-effect transistor memory with p-type channel. This demonstration opens the door for the development of non-volatile memory devices based on dual channel for emerging transparent and flexible electronic devices.

  4. Polymer ferroelectric field-effect memory device with SnO channel layer exhibits record hole mobility

    Science.gov (United States)

    Caraveo-Frescas, J. A.; Khan, M. A.; Alshareef, H. N.

    2014-06-01

    Here we report for the first time a hybrid p-channel polymer ferroelectric field-effect transistor memory device with record mobility. The memory device, fabricated at 200°C on both plastic polyimide and glass substrates, uses ferroelectric polymer P(VDF-TrFE) as the gate dielectric and transparent p-type oxide (SnO) as the active channel layer. A record mobility of 3.3 cm2V-1s-1, large memory window (~16 V), low read voltages (~-1 V), and excellent retention characteristics up to 5000 sec have been achieved. The mobility achieved in our devices is over 10 times higher than previously reported polymer ferroelectric field-effect transistor memory with p-type channel. This demonstration opens the door for the development of non-volatile memory devices based on dual channel for emerging transparent and flexible electronic devices.

  5. Highly flexible resistive switching memory based on amorphous-nanocrystalline hafnium oxide films.

    Science.gov (United States)

    Shang, Jie; Xue, Wuhong; Ji, Zhenghui; Liu, Gang; Niu, Xuhong; Yi, Xiaohui; Pan, Liang; Zhan, Qingfeng; Xu, Xiao-Hong; Li, Run-Wei

    2017-06-01

    Flexible and transparent resistive switching memories are highly desired for the construction of portable and even wearable electronics. Upon optimization of the microstructure wherein an amorphous-nanocrystalline hafnium oxide thin film is fabricated, an all-oxide based transparent RRAM device with stable resistive switching behavior that can withstand a mechanical tensile stress of up to 2.12% is obtained. It is demonstrated that the superior electrical, thermal and mechanical performance of the ITO/HfOx/ITO device can be ascribed to the formation of pseudo-straight metallic hafnium conductive filaments in the switching layer, and is only limited by the choice of electrode materials. When the ITO bottom electrode is replaced with platinum metal, the mechanical failure threshold of the device can be further extended.

  6. Attentional flexibility and memory capacity in conductors and pianists.

    Science.gov (United States)

    Wöllner, Clemens; Halpern, Andrea R

    2016-01-01

    Individuals with high working memory (WM) capacity also tend to have better selective and divided attention. Although both capacities are essential for skilled performance in many areas, evidence for potential training and expertise effects is scarce. We investigated the attentional flexibility of musical conductors by comparing them to equivalently trained pianists. Conductors must focus their attention both on individual instruments and on larger sections of different instruments. We studied students and professionals in both domains to assess the contributions of age and training to these skills. Participants completed WM span tests for auditory and visual (notated) pitches and timing durations, as well as long-term memory tests. In three dichotic attention tasks, they were asked to detect small pitch and timing deviations from two melodic streams presented in baseline (separate streams), selective-attention (concentrating on only one stream), and divided-attention (concentrating on targets in both streams simultaneously) conditions. Conductors were better than pianists in detecting timing deviations in divided attention, and experts detected more targets than students. We found no group differences for WM capacity or for pitch deviations in the attention tasks, even after controlling for the older age of the experts. Musicians' WM spans across multimodal conditions were positively related to selective and divided attention. High-WM participants also had shorter reaction times in selective attention. Taken together, conductors showed higher attentional flexibility in successfully switching between different foci of attention.

  7. A Flexible Microcontroller-Based Data Acquisition Device

    Directory of Open Access Journals (Sweden)

    Darko Hercog

    2014-06-01

    Full Text Available This paper presents a low-cost microcontroller-based data acquisition device. The key component of the presented solution is a configurable microcontroller-based device with an integrated USB transceiver and a 12-bit analogue-to-digital converter (ADC. The presented embedded DAQ device contains a preloaded program (firmware that enables easy acquisition and generation of analogue and digital signals and data transfer between the device and the application running on a PC via USB bus. This device has been developed as a USB human interface device (HID. This USB class is natively supported by most of the operating systems and therefore any installation of additional USB drivers is unnecessary. The input/output peripheral of the presented device is not static but rather flexible, and could be easily configured to customised needs without changing the firmware. When using the developed configuration utility, a majority of chip pins can be configured as analogue input, digital input/output, PWM output or one of the SPI lines. In addition, LabVIEW drivers have been developed for this device. When using the developed drivers, data acquisition and signal processing algorithms as well as graphical user interface (GUI, can easily be developed using a well-known, industry proven, block oriented LabVIEW programming environment.

  8. A flexible microcontroller-based data acquisition device.

    Science.gov (United States)

    Hercog, Darko; Gergič, Bojan

    2014-06-02

    This paper presents a low-cost microcontroller-based data acquisition device. The key component of the presented solution is a configurable microcontroller-based device with an integrated USB transceiver and a 12-bit analogue-to-digital converter (ADC). The presented embedded DAQ device contains a preloaded program (firmware) that enables easy acquisition and generation of analogue and digital signals and data transfer between the device and the application running on a PC via USB bus. This device has been developed as a USB human interface device (HID). This USB class is natively supported by most of the operating systems and therefore any installation of additional USB drivers is unnecessary. The input/output peripheral of the presented device is not static but rather flexible, and could be easily configured to customised needs without changing the firmware. When using the developed configuration utility, a majority of chip pins can be configured as analogue input, digital input/output, PWM output or one of the SPI lines. In addition, LabVIEW drivers have been developed for this device. When using the developed drivers, data acquisition and signal processing algorithms as well as graphical user interface (GUI), can easily be developed using a well-known, industry proven, block oriented LabVIEW programming environment.

  9. Flexible resistive switching memory using inkjet printing of a solid polymer electrolyte

    Directory of Open Access Journals (Sweden)

    Saumya R. Mohapatra

    2012-06-01

    Full Text Available Resistive switching memory cells were fabricated on a plastic substrate via inkjet printing (IJP of a solid polymer electrolyte (SPE. Using the high contrast between the surface energy of a metal electrode and the substrate, a thin SPE film could be deposited over the electrode by IJP. The fabricated Ag/SPE/Pt cells showed bipolar resistive switching behavior under electrical bias in vacuum and in air, which is attributed to the formation and dissolution of a metal filament between the electrodes. From the standpoint of the switching mechanism, our cell can be referred to as a ‘gapless-type atomic switch’. The cells also exhibited stable switching behavior under substrate bending. This device fabrication technique has great potential for flexible switch/memory applications.

  10. Flexible and twistable non-volatile memory cell array with all-organic one diode-one resistor architecture.

    Science.gov (United States)

    Ji, Yongsung; Zeigler, David F; Lee, Dong Su; Choi, Hyejung; Jen, Alex K-Y; Ko, Heung Cho; Kim, Tae-Wook

    2013-01-01

    Flexible organic memory devices are one of the integral components for future flexible organic electronics. However, high-density all-organic memory cell arrays on malleable substrates without cross-talk have not been demonstrated because of difficulties in their fabrication and relatively poor performances to date. Here we demonstrate the first flexible all-organic 64-bit memory cell array possessing one diode-one resistor architectures. Our all-organic one diode-one resistor cell exhibits excellent rewritable switching characteristics, even during and after harsh physical stresses. The write-read-erase-read output sequence of the cells perfectly correspond to the external pulse signal regardless of substrate deformation. The one diode-one resistor cell array is clearly addressed at the specified cells and encoded letters based on the standard ASCII character code. Our study on integrated organic memory cell arrays suggests that the all-organic one diode-one resistor cell architecture is suitable for high-density flexible organic memory applications in the future.

  11. Radiation Damage in Electronic Memory Devices

    OpenAIRE

    Irfan Fetahović; Milić Pejović; Miloš Vujisić

    2013-01-01

    This paper investigates the behavior of semiconductor memories exposed to radiation in order to establish their applicability in a radiation environment. The experimental procedure has been used to test radiation hardness of commercial semiconductor memories. Different types of memory chips have been exposed to indirect ionizing radiation by changing radiation dose intensity. The effect of direct ionizing radiation on semiconductor memory behavior has been analyzed by using Monte Carlo simula...

  12. Large-area, flexible imaging arrays constructed by light-charge organic memories

    Science.gov (United States)

    Zhang, Lei; Wu, Ti; Guo, Yunlong; Zhao, Yan; Sun, Xiangnan; Wen, Yugeng; Yu, Gui; Liu, Yunqi

    2013-01-01

    Existing organic imaging circuits, which offer attractive benefits of light weight, low cost and flexibility, are exclusively based on phototransistor or photodiode arrays. One shortcoming of these photo-sensors is that the light signal should keep invariant throughout the whole pixel-addressing and reading process. As a feasible solution, we synthesized a new charge storage molecule and embedded it into a device, which we call light-charge organic memory (LCOM). In LCOM, the functionalities of photo-sensor and non-volatile memory are integrated. Thanks to the deliberate engineering of electronic structure and self-organization process at the interface, 92% of the stored charges, which are linearly controlled by the quantity of light, retain after 20000 s. The stored charges can also be non-destructively read and erased by a simple voltage program. These results pave the way to large-area, flexible imaging circuits and demonstrate a bright future of small molecular materials in non-volatile memory. PMID:23326636

  13. Specifics and Challenges to Flexible Organic Light-Emitting Devices

    Directory of Open Access Journals (Sweden)

    Mariya Aleksandrova

    2016-01-01

    Full Text Available Several recent developments in material science and deposition methods for flexible organic light-emitting devices (OLEDs are surveyed. The commonly used plastic substrates are compared, according to their mechanical, optical, thermal, and chemical properties. Multilayer electrode structures, used as transparent electrodes, replacing conventional indium tin oxide (ITO are presented and data about their conductivity, transparency, and bending ability are provided. Attention is paid to some of the most popular industrial processes for flexible OLEDs manufacturing, such as roll-to-roll printing, inkjet printing, and screen printing. Main specifics and challenges, related to the foils reliability, mechanical stability of the transparent electrodes, and deposition and patterning of organic emissive films, are discussed.

  14. Memory-assisted measurement-device-independent quantum key distribution

    Science.gov (United States)

    Panayi, Christiana; Razavi, Mohsen; Ma, Xiongfeng; Lütkenhaus, Norbert

    2014-04-01

    A protocol with the potential of beating the existing distance records for conventional quantum key distribution (QKD) systems is proposed. It borrows ideas from quantum repeaters by using memories in the middle of the link, and that of measurement-device-independent QKD, which only requires optical source equipment at the user's end. For certain memories with short access times, our scheme allows a higher repetition rate than that of quantum repeaters with single-mode memories, thereby requiring lower coherence times. By accounting for various sources of nonideality, such as memory decoherence, dark counts, misalignment errors, and background noise, as well as timing issues with memories, we develop a mathematical framework within which we can compare QKD systems with and without memories. In particular, we show that with the state-of-the-art technology for quantum memories, it is potentially possible to devise memory-assisted QKD systems that, at certain distances of practical interest, outperform current QKD implementations.

  15. Forced Ion Migration for Chalcogenide Phase Change Memory Device

    Science.gov (United States)

    Campbell, Kristy A (Inventor)

    2013-01-01

    Non-volatile memory devices with two stacked layers of chalcogenide materials comprising the active memory device have been investigated for their potential as phase-change memories. The devices tested included GeTe/SnTe, Ge2Se3/SnTe, and Ge2Se3/SnSe stacks. All devices exhibited resistance switching behavior. The polarity of the applied voltage with respect to the SnTe or SnSe layer was critical to the memory switching properties, due to the electric field induced movement of either Sn or Te into the Ge-chalcogenide layer. One embodiment of the invention is a device comprising a stack of chalcogenide-containing layers which exhibit phase-change switching only after a reverse polarity voltage potential is applied across the stack causing ion movement into an adjacent layer and thus "activating" the device to act as a phase-change random access memory device or a reconfigurable electronics device when the applied voltage potential is returned to the normal polarity. Another embodiment of the invention is a device that is capable of exhibiting more than two data states.

  16. From the bottom up--flexible solid state electrochromic devices.

    Science.gov (United States)

    Jensen, Jacob; Krebs, Frederik C

    2014-11-12

    Solid-state flexible polymer-based electrochromic devices are fabricated continuously by stacking layers in one direction. This novel bottom-up approach with no need for a lamination step is realized through in situ photo-crosslinking of the electrolyte using a "curing-chamber" fitted to a roll-coater, which lowers the oxygen concentration at the electrolyte surface. This enables fully printed and 2D patterned organic electrochromics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Radiation Damage in Electronic Memory Devices

    Directory of Open Access Journals (Sweden)

    Irfan Fetahović

    2013-01-01

    Full Text Available This paper investigates the behavior of semiconductor memories exposed to radiation in order to establish their applicability in a radiation environment. The experimental procedure has been used to test radiation hardness of commercial semiconductor memories. Different types of memory chips have been exposed to indirect ionizing radiation by changing radiation dose intensity. The effect of direct ionizing radiation on semiconductor memory behavior has been analyzed by using Monte Carlo simulation method. Obtained results show that gamma radiation causes decrease in threshold voltage, being proportional to the absorbed dose of radiation. Monte Carlo simulations of radiation interaction with material proved to be significant and can be a good estimation tool in probing semiconductor memory behavior in radiation environment.

  18. Multilayer Polymeric Encapsulation of Flexible Organic Photovoltaic Devices

    Science.gov (United States)

    Madakasira, Pallavi

    2005-03-01

    Flexible solar cells, based on conjugated polymeric D-A systems have stimulated considerable interest recently. We obtained efficiencies ˜4% in heat-treated PHT/PCBM based solar cells [1]. These have the advantage of being mounted easily on either a flat or curved surface. One of the major problems is their protection from degradation due to exposure to air and moisture under intense light irradiation.These necessitate use of flexible encapsulation. Parylene has been used to encapsulate various devices,like OLEDs [2,3]. It is stable when deposited on devices in vacuum. First results on conformal deposition on solar cells is reported here, and effects of protection depending on the thickness of parylene film. It provides pin-hole free coating for dielectric protection. [1] K. Inoue, R. Ulbricht, P. C. Madakasira, W.M. Sampson, S. Lee, J. Gutierrez, J. Ferraris and A. A. Zakhidov,Proc. of SPIE -- Org. Photovoltaics V, 5520, p.256-262 (2004). [2]Z.Zhang, G.Xiao, J.Liu and C.P. Grover, Fiber and Integrated Optics,22:343-355-2003 [3] Y.S. Jeong, B.Ratier, A. Moliton and L.Guyard, Synthetic Materials 127 (2002) 189-193

  19. Liquid Self-Balancing Device Effects on Flexible Rotor Stability

    Directory of Open Access Journals (Sweden)

    Leonardo Urbiola-Soto

    2013-01-01

    Full Text Available Nearly a century ago, the liquid self-balancing device was first introduced by M. LeBlanc for passive balancing of turbine rotors. Although of common use in many types or rotating machines nowadays, little information is available on the unbalance response and stability characteristics of this device. Experimental fluid flow visualization evidences that radial and traverse circulatory waves arise due to the interaction of the fluid backward rotation and the baffle boards within the self-balancer annular cavity. The otherwise destabilizing force induced by trapped fluids in hollow rotors, becomes a stabilizing mechanism when the cavity is equipped with adequate baffle boards. Further experiments using Particle Image Velocimetry (PIV enable to assess the active fluid mass fraction to be one-third of the total fluid mass. An analytical model is introduced to study the effects of the active fluid mass fraction on a flexible rotor supported by flexible supports excited by bwo different destabilizing mechanisms; rotor internal friction damping and aerodynamic cross-coupling. It is found that the fluid radial and traverse forces contribute to the balancing action and to improve the rotor stability, respectively.

  20. Nonvolatile WORM memory devices based on polymethacrylate with azoanthraquinone group

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel polymethacrylate containing azoanthraquinone chromophore in the side chain(PMAzoaq6) was synthesized and characterized.An electronic memory device having the indium-tin oxide(ITO)/PMAzoaq6/Al sandwich structure was fabricated and its electrical bistability was investigated.The as-fabricated device was initially found to be at the OFF state and the switching threshold voltage was 1.5 V.After undergoing the OFF-to-ON transition,the device maintains the high conducting state(ON state) even after turning off the electrical power and applying a reverse bias.The device exhibits a write-once-read-many-times(WORM) memory effect with a high ON/OFF current ratio of up to 105 and a long retention time in both ON and OFF states,which demonstrated that the synthetic azoanthraquinone-containing polymer possesses a high potential to become polymeric memory devices.

  1. A Novel Memory Structure for Embedded Systems: Flexible Sequential and Random Access Memory

    Institute of Scientific and Technical Information of China (English)

    Ying Chen; Karthik Ranganathan; Vasudev V. Pai; David J. Lilja; Kia Bazargan

    2005-01-01

    The on-chip memory performance of embedded systems directly affects the system designers' decision about how to allocate expensive silicon area. A novel memory architecture, flexible sequential and random access memory (FSRAM),is investigated for embedded systems. To realize sequential accesses, small "links" are added to each row in the RAM array to point to the next row to be prefetched. The potential cache pollution is ameliorated by a small sequential access buffer (SAB). To evaluate the architecture-level performance of FSRAM, we ran the Mediabench benchmark programs on a modified version of the SimpleScalar simulator. Our results show that the FSRAM improves the performance of a baseline processor with a 16KB data cache up to 55%, with an average of 9%; furthermore, the FSRAM reduces 53.1% of the data cache miss count on average due to its prefetching effect. We also designed RTL and SPICE models of the FSRAM, which show that the FSRAM significantly improves memory access time, while reducing power consumption, with negligible area overhead.

  2. Coding with Side Information for Radiation-Tolerant Memory Devices

    Science.gov (United States)

    Hwang, E.; Jeon, S.; Negi, R.; Vijaya Kumar, B. V. K.; Cheng, M. K.

    2011-11-01

    Memory devices aboard spacecraft experience radiation-induced errors either in the form of temporary upsets (soft errors) or permanent defects (hard or stuck-at errors). Error-correcting codes (ECCs) are used to recover memory content from errors where defective cells are either regarded as erasures by the decoder or entire blocks containing defective cells are marked as unusable. In this article, alternative coding schemes are investigated for memory devices in space, where the encoder is provided with the locations of the defective cells, denoted by side information. This coding approach has the potential to improve the overall storage capacity of memory devices, since the information theoretic capacity of a channel where side information is only available at the encoder is the same as the capacity where side information is available at both the encoder and decoder. Spacecraft memory controllers typically scrub memory devices periodically for errors. Partial side information can be obtained during this scrubbing process by comparing the ECC decoder output with its input and thereby avoid the need for additional cell tests or storage overhead. In between scrubbings, the encoder can use this partial side information to account for permanent defects to improve reliability or to increase the storage capacity of onboard memory devices. In order to achieve performance gains for practical memory systems, several coding schemes that adaptively incorporate the codeword with the known side information are proposed in this article. The proposed coding schemes are evaluated by numerical simulations on a memory channel model characterized by soft and hard errors. Simulation results show that while coding with complete side information at the encoder offers the most performance gain compared to when coding without side information is used, coding with partial side information can close the gap between the optimal and current approach without incurring much additional overhead

  3. First principles modeling of magnetic random access memory devices (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Butler, W.H.; Zhang, X.; Schulthess, T.C.; Nicholson, D.M.; Oparin, A.B. [Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); MacLaren, J.M. [Department of Physics, Tulane University, New Orleans, Louisiana 70018 (United States)

    1999-04-01

    Giant magnetoresistance (GMR) and spin-dependent tunneling may be used to make magnetic random access memory devices. We have applied first-principles based electronic structure techniques to understand these effects and in the case of GMR to model the transport properties of the devices. {copyright} {ital 1999 American Institute of Physics.}

  4. Electrically conductive lines on cellulose nanopaper for flexible electrical devices

    Science.gov (United States)

    Hsieh, Ming-Chun; Kim, Changjae; Nogi, Masaya; Suganuma, Katsuaki

    2013-09-01

    Highly conductive circuits are fabricated on nanopapers composed of densely packed 15-60 nm wide cellulose nanofibers. Conductive materials are deposited on the nanopaper and mechanically sieved through the densely packed nanofiber networks. As a result, their conductivity is enhanced to the level of bulk silver and LED lights are successfully illuminated via these metallic conductive lines on the nanopaper. Under the same deposition conditions, traditional papers consisting of micro-sized pulp fibers produced very low conductivity lines with non-uniform boundaries because of their larger pore structures. These results indicate that advanced, lightweight and highly flexible devices can be realized on cellulose nanopaper using continuous deposition processes. Continuous deposition on nanopaper is a promising approach for a simple roll-to-roll manufacturing process.

  5. Flexible fiber energy storage and integrated devices: recent progress and perspectives

    OpenAIRE

    Xianfu Wang; Kai Jiang; Guozhen Shen

    2015-01-01

    Flexible fiber-shaped energy storage devices have been studied and developed intensively over the past few years to meet the demands of modern electronics in terms of flexibility, weavability and being lightweight. In this review, fiber electrodes and flexible fiber energy storage devices containing solid-state supercapacitors (SCs) and lithium-ion batteries (LIBs) are carefully summarized with particular emphasis on their electrode fabrication, structure design and flexibility. In addition, ...

  6. The role of verbal labels on flexible memory retrieval at 12-months of age.

    Science.gov (United States)

    Taylor, Gemma; Liu, Hao; Herbert, Jane S

    2016-11-01

    The provision of verbal labels enhances 12-month-old infants' memory flexibility across a form change in a puppet imitation task (Herbert, 2011), although the mechanisms for this effect remain unclear. Here we investigate whether verbal labels can scaffold flexible memory retrieval when task difficulty increases and consider the mechanism responsible for the effect of language cues on early memory flexibility. Twelve-month-old infants were provided with English, Chinese, or empty language cues during a difficult imitation task, a combined change in the puppet's colour and form at the test (Hayne et al., 1997). Imitation performance by infants in the English language condition only exceeded baseline performance after the 10-min delay. Thus, verbal labels facilitated flexible memory retrieval on this task. There were no correlations between infants' language comprehension and imitation performance. Thus, it is likely that verbal labels facilitate both attention and categorisation during encoding and retrieval.

  7. Pattern recognition with magnonic holographic memory device

    Energy Technology Data Exchange (ETDEWEB)

    Kozhevnikov, A.; Dudko, G.; Filimonov, Y. [Kotel' nikov Institute of Radioengineering and Electronics of Russian Academy of Sciences, Saratov Branch, Saratov 410019 (Russian Federation); Gertz, F.; Khitun, A. [Electrical Engineering Department, University of California - Riverside, Riverside, California 92521 (United States)

    2015-04-06

    In this work, we present experimental data demonstrating the possibility of using magnonic holographic devices for pattern recognition. The prototype eight-terminal device consists of a magnetic matrix with micro-antennas placed on the periphery of the matrix to excite and detect spin waves. The principle of operation is based on the effect of spin wave interference, which is similar to the operation of optical holographic devices. Input information is encoded in the phases of the spin waves generated on the edges of the magnonic matrix, while the output corresponds to the amplitude of the inductive voltage produced by the interfering spin waves on the other side of the matrix. The level of the output voltage depends on the combination of the input phases as well as on the internal structure of the magnonic matrix. Experimental data collected for several magnonic matrixes show the unique output signatures in which maxima and minima correspond to specific input phase patterns. Potentially, magnonic holographic devices may provide a higher storage density compare to optical counterparts due to a shorter wavelength and compatibility with conventional electronic devices. The challenges and shortcoming of the magnonic holographic devices are also discussed.

  8. Design of a Multi-Level/Analog Ferroelectric Memory Device

    Science.gov (United States)

    MacLeod, Todd C.; Phillips, Thomas A.; Ho, Fat D.

    2006-01-01

    Increasing the memory density and utilizing the dove1 characteristics of ferroelectric devices is important in making ferroelectric memory devices more desirable to the consumer. This paper describes a design that allows multiple levels to be stored in a ferroelectric based memory cell. It can be used to store multiple bits or analog values in a high speed nonvolatile memory. The design utilizes the hysteresis characteristic of ferroelectric transistors to store an analog value in the memory cell. The design also compensates for the decay of the polarization of the ferroelectric material over time. This is done by utilizing a pair of ferroelectric transistors to store the data. One transistor is used as a reference to determine the amount of decay that has occurred since the pair was programmed. The second transistor stores the analog value as a polarization value between zero and saturated. The design allows digital data to be stored as multiple bits in each memory cell. The number of bits per cell that can be stored will vary with the decay rate of the ferroelectric transistors and the repeatability of polarization between transistors. It is predicted that each memory cell may be able to store 8 bits or more. The design is based on data taken from actual ferroelectric transistors. Although the circuit has not been fabricated, a prototype circuit is now under construction. The design of this circuit is different than multi-level FLASH or silicon transistor circuits. The differences between these types of circuits are described in this paper. This memory design will be useful because it allows higher memory density, compensates for the environmental and ferroelectric aging processes, allows analog values to be directly stored in memory, compensates for the thermal and radiation environments associated with space operations, and relies only on existing technologies.

  9. Design of a Multi-Level/Analog Ferroelectric Memory Device

    Science.gov (United States)

    MacLeod, Todd C.; Phillips, Thomas A.; Ho, Fat D.

    2006-01-01

    Increasing the memory density and utilizing the dove1 characteristics of ferroelectric devices is important in making ferroelectric memory devices more desirable to the consumer. This paper describes a design that allows multiple levels to be stored in a ferroelectric based memory cell. It can be used to store multiple bits or analog values in a high speed nonvolatile memory. The design utilizes the hysteresis characteristic of ferroelectric transistors to store an analog value in the memory cell. The design also compensates for the decay of the polarization of the ferroelectric material over time. This is done by utilizing a pair of ferroelectric transistors to store the data. One transistor is used as a reference to determine the amount of decay that has occurred since the pair was programmed. The second transistor stores the analog value as a polarization value between zero and saturated. The design allows digital data to be stored as multiple bits in each memory cell. The number of bits per cell that can be stored will vary with the decay rate of the ferroelectric transistors and the repeatability of polarization between transistors. It is predicted that each memory cell may be able to store 8 bits or more. The design is based on data taken from actual ferroelectric transistors. Although the circuit has not been fabricated, a prototype circuit is now under construction. The design of this circuit is different than multi-level FLASH or silicon transistor circuits. The differences between these types of circuits are described in this paper. This memory design will be useful because it allows higher memory density, compensates for the environmental and ferroelectric aging processes, allows analog values to be directly stored in memory, compensates for the thermal and radiation environments associated with space operations, and relies only on existing technologies.

  10. Terrestrial neutron-induced soft errors in advanced memory devices

    CERN Document Server

    Nakamura, Takashi; Ibe, Eishi; Yahagi, Yasuo; Kameyama, Hideaki

    2008-01-01

    Terrestrial neutron-induced soft errors in semiconductor memory devices are currently a major concern in reliability issues. Understanding the mechanism and quantifying soft-error rates are primarily crucial for the design and quality assurance of semiconductor memory devices. This book covers the relevant up-to-date topics in terrestrial neutron-induced soft errors, and aims to provide succinct knowledge on neutron-induced soft errors to the readers by presenting several valuable and unique features. Sample Chapter(s). Chapter 1: Introduction (238 KB). Table A.30 mentioned in Appendix A.6 on

  11. Inverse heat conduction problem in a phase change memory device

    Science.gov (United States)

    Battaglia, Jean-Luc; De, Indrayush; Sousa, Véronique

    2017-01-01

    An invers heat conduction problem is solved considering the thermal investigation of a phase change memory device using the scanning thermal microscopy. The heat transfer model rests on system identification for the probe thermal impedance and on a finite element method for the device thermal impedance. Unknown parameters in the model are then identified using a nonlinear least square algorithm that minimizes the quadratic gap between the measured probe temperature and the simulated one.

  12. Toward flexible and wearable human-interactive health-monitoring devices.

    Science.gov (United States)

    Takei, Kuniharu; Honda, Wataru; Harada, Shingo; Arie, Takayuki; Akita, Seiji

    2015-03-11

    This Progress Report introduces flexible wearable health-monitoring devices that interact with a person by detecting from and stimulating the body. Interactive health-monitoring devices should be highly flexible and attach to the body without awareness like a bandage. This type of wearable health-monitoring device will realize a new class of electronics, which will be applicable not only to health monitoring, but also to other electrical devices. However, to realize wearable health-monitoring devices, many obstacles must be overcome to economically form the active electrical components on a flexible substrate using macroscale fabrication processes. In particular, health-monitoring sensors and curing functions need to be integrated. Here recent developments and advancements toward flexible health-monitoring devices are presented, including conceptual designs of human-interactive devices.

  13. Flexible fiber energy storage and integrated devices: recent progress and perspectives

    Directory of Open Access Journals (Sweden)

    Xianfu Wang

    2015-06-01

    Full Text Available Flexible fiber-shaped energy storage devices have been studied and developed intensively over the past few years to meet the demands of modern electronics in terms of flexibility, weavability and being lightweight. In this review, fiber electrodes and flexible fiber energy storage devices containing solid-state supercapacitors (SCs and lithium-ion batteries (LIBs are carefully summarized with particular emphasis on their electrode fabrication, structure design and flexibility. In addition, emerging wire-shaped integrated energy systems, combined energy storage and solar cells, as well as other electronic devices to realize self-charging and self-powered integrated systems are specifically highlighted.

  14. The analysis of polarization characteristics on 40nm memory devices

    Science.gov (United States)

    Yoo, Minae; Park, Chanha; You, Taejun; Yang, Hyunjo; Min, Young-Hong; Park, Ki-Yeop; Yim, Donggyu; Park, Sungki

    2009-03-01

    Hyper NA system has been introduced to develop sub-60nm node memory devices. Especially memory industries including DRAM and NAND Flash business have driven much finer technology to improve productivity. Polarization at hyper NA has been well known as important optical technology to enhance imaging performance and also achieve very low k1 process. The source polarization on dense structure has been used as one of the major RET techniques. The process capabilities of various layers under specific illumination and polarization have been explored. In this study, polarization characteristic on 40nm memory device will be analyzed. Especially, TE (Transverse Electric) polarization and linear X-Y polarization on hyper NA ArF system will be compared and investigated. First, IPS (Intensity in Preferred State) value will be measured with PMM (Polarization Metrology Module) to confirm polarization characteristic of each machine before simulation. Next simulation will be done to estimate the CD variation impact of each polarization to different illumination. Third, various line and space pattern of DRAM and Flash device will be analyzed under different polarized condition to see the effect of polarization on CD of actual wafer. Finally, conclusion will be made for this experiment and future work will be discussed. In this paper, the behavior of 40nm node memory devices with two types of polarization is presented and the guidelines for polarization control is discussed based on the patterning performances.

  15. Thin PZT-Based Ferroelectric Capacitors on Flexible Silicon for Nonvolatile Memory Applications

    KAUST Repository

    Ghoneim, Mohamed T.

    2015-04-24

    A flexible version of traditional thin lead zirconium titanate ((Pb1.1Zr0.48Ti0.52O3)-(PZT)) based ferroelectric random access memory (FeRAM) on silicon shows record performance in flexible arena. The thin PZT layer requires lower operational voltages to achieve coercive electric fields, reduces the sol-gel coating cycles required (i.e., more cost-effective), and, fabrication wise, is more suitable for further scaling of lateral dimensions to the nano-scale due to the larger feature size-to-depth aspect ratio (critical for ultra-high density non-volatile memory applications). Utilizing the inverse proportionality between substrate\\'s thickness and its flexibility, traditional PZT based FeRAM on silicon is transformed through a transfer-less manufacturable process into a flexible form that matches organic electronics\\' flexibility while preserving the superior performance of silicon CMOS electronics. Each memory cell in a FeRAM array consists of two main elements; a select/access transistor, and a storage ferroelectric capacitor. Flexible transistors on silicon have already been reported. In this work, we focus on the storage ferroelectric capacitors, and report, for the first time, its performance after transformation into a flexible version, and assess its key memory parameters while bent at 0.5 cm minimum bending radius.

  16. Automatic memory management policies for low power, memory limited, and delay intolerant devices

    Science.gov (United States)

    Jahid, Md. Abu

    Mobile devices such as smartphones and tablets are energy and memory limited, and implement graphical user interfaces that are intolerant of computational delays. Mobile device platforms supporting apps implemented in languages that require automatic memory management, such as the Dalvik (Java) virtual machine within Google's Android, have become dominant. It is essential that automatic memory management avoid causing unacceptable interface delays while responsibly managing energy and memory resource usage. Dalvik's automatic memory management policies for heap growth and garbage collection scheduling utilize heuristics tuned to minimize memory footprint. These policies result in only marginally acceptable response times and garbage collection signicantly contributes to apps' CPU time and therefore energy consumption. The primary contributions of this research include a characterization of Dalvik's "baseline" automatic memory management policy, the development of a new "adaptive" policy, and an investigation of the performance of this policy. The investigation indicates that this adaptive policy consumes less CPU time and improves interactive performance at the cost of increasing memory footprint size by an acceptable amount.

  17. New hybrid encapsulation for flexible organic light-emitting devices on plastic substrates

    Institute of Scientific and Technical Information of China (English)

    LIU Song; ZHANG DeQiang; LI Yang; DUAN Lian; DONG GuiFang; WANG LiDuo; QIU Yong

    2008-01-01

    The hybrid encapsulation for flexible organic light-emitting devices on plastic substrate was investi-gated. The hybrid encapsulation consisted of four periods of Alq3/LiF layers as the pre-encapsulation layer and a flexible aluminum foil coated with getter as the encapsulation cap. We measured the device lifetime at a continuous constant current of 20 mA/cm2, which corresponded to an initial luminance of 2000 cd/m2, The half-luminance decay time of the encapsulated device was about 458 h. More over, the hybrid encapsulation is ultrathin and flexible, ensuring device bendability.

  18. Multilevel conductance switching of memory device through photoelectric effect.

    Science.gov (United States)

    Ye, Changqing; Peng, Qian; Li, Mingzhu; Luo, Jia; Tang, Zhengming; Pei, Jian; Chen, Jianming; Shuai, Zhigang; Jiang, Lei; Song, Yanlin

    2012-12-12

    A photoelectronic switch of a multilevel memory device has been achieved using a meta-conjugated donor-bridge-acceptor (DBA) molecule. Such a DBA optoelectronic molecule responds to both the optical and electrical stimuli. The device exhibits good electrical bistable switching behaviors under dark, with a large ON/OFF ratio more than 10(6). In cooperation with the UV light, photoelectronic ternary states are addressable in a bistable switching system. On the basis of the CV measurement, charge carriers transport modeling, quantum chemical calculation, and absorption spectra analysis, the mechanism of the DBA memory is suggested to be attributed to the substep charge transfer transition process. The capability of tailoring photoelectrical properties is a very promising strategy to explore the multilevel storage, and it will give a new opportunity for designing multifunctional devices.

  19. Flexible bio-memristive devices based on chicken egg albumen:Au@SiO2 core-shell nanoparticle nanocomposites.

    Science.gov (United States)

    Bok, Chang Han; Woo, Sung Jun; Wu, Chaoxing; Park, Jae Hyeon; Kim, Tae Whan

    2017-09-20

    Flexible bio-memristive (FBM) devices utilizing chicken egg albumen (CEA):Au@SiO2 core-shell nanoparticle nanocomposites were fabricated on indium-tin-oxide (ITO) coated polyethylene naphthalate (PEN) substrates. Current-voltage (I-V) curves for the Al/CEA:Au@SiO2 core-shell nanoparticle/ITO/PEN devices showed clockwise current hysteresis behaviors due to the existence of the CEA:Au@SiO2 core-shell nanoparticle nanocomposites. The endurance number of the ON/OFF switching for the FBM devices was above 10(2) cycles. An ON/OFF current ratio of 1 × 10(5) was maintained for retention times longer than 1 × 10(4) s. The memory characteristics of the FBM devices after bending were similar to those before bending. The memory margin and the stability of FBM devices were enhanced due to the embedded Au@SiO2 core-shell nanoparticles. The switching mechanisms occurring in the Al/CEA:Au@SiO2 core-shell nanoparticle/ITO-coated PEN devices are described on the basis of the I-V results and the filament mechanisms.

  20. Improving Memory Characteristics of Hydrogenated Nanocrystalline Silicon Germanium Nonvolatile Memory Devices by Controlling Germanium Contents.

    Science.gov (United States)

    Kim, Jiwoong; Jang, Kyungsoo; Phu, Nguyen Thi Cam; Trinh, Thanh Thuy; Raja, Jayapal; Kim, Taeyong; Cho, Jaehyun; Kim, Sangho; Park, Jinjoo; Jung, Junhee; Lee, Youn-Jung; Yi, Junsin

    2016-05-01

    Nonvolatile memory (NVM) with silicon dioxide/silicon nitride/silicon oxynitride (ONO(n)) charge trap structure is a promising flash memory technology duo that will fulfill process compatibility for system-on-panel displays, down-scaling cell size and low operation voltage. In this research, charge trap flash devices were fabricated with ONO(n) stack gate insulators and an active layer using hydrogenated nanocrystalline silicon germanium (nc-SiGe:H) films at a low temperature. In this study, the effect of the interface trap density on the performance of devices, including memory window and retention, was investigated. The electrical characteristics of NVM devices were studied controlling Ge content from 0% to 28% in the nc-SiGe:H channel layer. The optimal Ge content in the channel layer was found to be around 16%. For nc-SiGe:H NVM with 16% Ge content, the memory window was 3.13 V and the retention data exceeded 77% after 10 years under the programming condition of 15 V for 1 msec. This showed that the memory window increased by 42% and the retention increased by 12% compared to the nc-Si:H NVM that does not contain Ge. However, when the Ge content was more than 16%, the memory window and retention property decreased. Finally, this research showed that the Ge content has an effect on the interface trap density and this enabled us to determine the optimal Ge content.

  1. Metal-free, single-polymer device exhibits resistive memory effect

    KAUST Repository

    Bhansali, Unnat Sampatraj

    2013-12-23

    All-polymer, write-once-read-many times resistive memory devices have been fabricated on flexible substrates using a single polymer, poly(3,4- ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). Spin-cast or inkjet-printed films of solvent-modified PEDOT:PSS are used as electrodes, while the unmodified or as-is PEDOT:PSS is used as the semiconducting active layer. The all-polymer devices exhibit an irreversible but stable transition from a low resistance state (ON) to a high resistance state (OFF) at low voltages caused by an electric-field-induced morphological rearrangement of PEDOT and PSS at the electrode interface. However, in the metal-PEDOT:PSS-metal devices, we have shown a metal filament formation switching the device from an initial high resistance state (OFF) to the low resistance state (ON). The all-PEDOT:PSS memory device has low write voltages (<3 V), high ON/OFF ratio (>10 3), good retention characteristics (>10 000 s), and stability in ambient storage (>3 months). © 2013 American Chemical Society.

  2. Carbon Nanotubes and Graphene for Flexible Electrochemical Energy Storage: from Materials to Devices.

    Science.gov (United States)

    Wen, Lei; Li, Feng; Cheng, Hui-Ming

    2016-06-01

    Flexible electrochemical energy storage (FEES) devices have received great attention as a promising power source for the emerging field of flexible and wearable electronic devices. Carbon nanotubes (CNTs) and graphene have many excellent properties that make them ideally suited for use in FEES devices. A brief definition of FEES devices is provided, followed by a detailed overview of various structural models for achieving different FEES devices. The latest research developments on the use of CNTs and graphene in FEES devices are summarized. Finally, future prospects and important research directions in the areas of CNT- and graphene-based flexible electrode synthesis and device integration are discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Computerised memory: digital devices and writing the self

    Directory of Open Access Journals (Sweden)

    Oriane DESEILLIGNY

    2012-01-01

    Full Text Available Based on the analysis of the diary’s textual form, this paper examines the way the latter is quoted and transformed with digital devices. Reviewing handwritten or digitised diaries, weblogs and Facebook, we observe the transformations of this textual form as well as the values invested by its users, devices and media.We compare the link with memory in each medium and the way it can – or cannot – be analysed in terms of writing the self, according to Foucault.

  4. Fabrication techniques and applications of flexible graphene-based electronic devices

    Science.gov (United States)

    Luqi, Tao; Danyang, Wang; Song, Jiang; Ying, Liu; Qianyi, Xie; He, Tian; Ningqin, Deng; Xuefeng, Wang; Yi, Yang; Tian-Ling, Ren

    2016-04-01

    In recent years, flexible electronic devices have become a hot topic of scientific research. These flexible devices are the basis of flexible circuits, flexible batteries, flexible displays and electronic skins. Graphene-based materials are very promising for flexible electronic devices, due to their high mobility, high elasticity, a tunable band gap, quantum electronic transport and high mechanical strength. In this article, we review the recent progress of the fabrication process and the applications of graphene-based electronic devices, including thermal acoustic devices, thermal rectifiers, graphene-based nanogenerators, pressure sensors and graphene-based light-emitting diodes. In summary, although there are still a lot of challenges needing to be solved, graphene-based materials are very promising for various flexible device applications in the future. Project supported by the National Natural Science Foundation of China (Nos. 60936002, 61025021, 61434001, 61574083), the State Key Development Program for Basic Research of China (No. 2015CB352100), the National Key Project of Science and Technology (No. 2011ZX02403-002) and the Special Fund for Agroscientific Research in the Public Interest of China (No. 201303107). M.A.M is additionally supported by the Postdoctoral Fellowship (PDF) Program of the Natural Sciences and Engineering Research Council (NSERC) of Canada and China's Postdoctoral Science Foundation (CPSF).

  5. RFID and Memory Devices Fabricated Integrally on Substrates

    Science.gov (United States)

    Schramm, Harry F.

    2004-01-01

    Electronic identification devices containing radio-frequency identification (RFID) circuits and antennas would be fabricated integrally with the objects to be identified, according to a proposal. That is to say, the objects to be identified would serve as substrates for the deposition and patterning of the materials of the devices used to identify them, and each identification device would be bonded to the identified object at the molecular level. Vacuum arc vapor deposition (VAVD) is the NASA derived process for depositing layers of material on the substrate. This proposal stands in contrast to the current practice of fabricating RFID and/or memory devices as wafer-based, self-contained integrated-circuit chips that are subsequently embedded in or attached to plastic cards to make smart account-information cards and identification badges. If one relies on such a chip to store data on the history of an object to be tracked and the chip falls off or out of the object, then one loses both the historical data and the means to track the object and verify its identity electronically. Also, in contrast is the manufacturing philosophy in use today to make many memory devices. Today s methods involve many subtractive processes such as etching. This proposal only uses additive methods, building RFID and memory devices from the substrate up in thin layers. VAVD is capable of spraying silicon, copper, and other materials commonly used in electronic devices. The VAVD process sprays most metals and some ceramics. The material being sprayed has a very strong bond with the substrate, whether that substrate is metal, ceramic, or even wood, rock, glass, PVC, or paper. An object to be tagged with an identification device according to the proposal must be compatible with a vacuum deposition process. Temperature is seldom an issue as the substrate rarely reaches 150 F (66 C) during the deposition process. A portion of the surface of the object would be designated as a substrate for

  6. Flexible Graphene-based Energy Storage Devices for Space Application Project

    Science.gov (United States)

    Calle, Carlos I.

    2014-01-01

    Develop prototype graphene-based reversible energy storage devices that are flexible, thin, lightweight, durable, and that can be easily attached to spacesuits, rovers, landers, and equipment used in space.

  7. Manufacturing and testing flexible microfluidic devices with optical and electrical detection mechanisms

    NARCIS (Netherlands)

    Ivan, M.G.; Vivet, F.; Meinders, E.R.

    2010-01-01

    Flexible microfluidic devices made of poly(dimethylsiloxane) (PDMS) were manufactured by soft lithography, and tested in detection of ionic species using optical absorption spectroscopy and electrical measurements. PDMS was chosen due to its flexibility and ease of surface modification by exposure

  8. Manufacturing and testing flexible microfluidic devices with optical and electrical detection mechanisms

    NARCIS (Netherlands)

    Ivan, M.G.; Vivet, F.; Meinders, E.R.

    2010-01-01

    Flexible microfluidic devices made of poly(dimethylsiloxane) (PDMS) were manufactured by soft lithography, and tested in detection of ionic species using optical absorption spectroscopy and electrical measurements. PDMS was chosen due to its flexibility and ease of surface modification by exposure t

  9. Stretchable carbon nanotube charge-trap floating-gate memory and logic devices for wearable electronics.

    Science.gov (United States)

    Son, Donghee; Koo, Ja Hoon; Song, Jun-Kyul; Kim, Jaemin; Lee, Mincheol; Shim, Hyung Joon; Park, Minjoon; Lee, Minbaek; Kim, Ji Hoon; Kim, Dae-Hyeong

    2015-05-26

    Electronics for wearable applications require soft, flexible, and stretchable materials and designs to overcome the mechanical mismatch between the human body and devices. A key requirement for such wearable electronics is reliable operation with high performance and robustness during various deformations induced by motions. Here, we present materials and device design strategies for the core elements of wearable electronics, such as transistors, charge-trap floating-gate memory units, and various logic gates, with stretchable form factors. The use of semiconducting carbon nanotube networks designed for integration with charge traps and ultrathin dielectric layers meets the performance requirements as well as reliability, proven by detailed material and electrical characterizations using statistics. Serpentine interconnections and neutral mechanical plane layouts further enhance the deformability required for skin-based systems. Repetitive stretching tests and studies in mechanics corroborate the validity of the current approaches.

  10. A triple quantum dot based nano-electromechanical memory device

    Energy Technology Data Exchange (ETDEWEB)

    Pozner, R.; Lifshitz, E. [Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Solid State Institute, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Peskin, U., E-mail: uri@tx.technion.ac.il [Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Lise Meitner Center for Computational Quantum Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

    2015-09-14

    Colloidal quantum dots (CQDs) are free-standing nano-structures with chemically tunable electronic properties. This tunability offers intriguing possibilities for nano-electromechanical devices. In this work, we consider a nano-electromechanical nonvolatile memory (NVM) device incorporating a triple quantum dot (TQD) cluster. The device operation is based on a bias induced motion of a floating quantum dot (FQD) located between two bound quantum dots (BQDs). The mechanical motion is used for switching between two stable states, “ON” and “OFF” states, where ligand-mediated effective interdot forces between the BQDs and the FQD serve to hold the FQD in each stable position under zero bias. Considering realistic microscopic parameters, our quantum-classical theoretical treatment of the TQD reveals the characteristics of the NVM.

  11. Resistive switching characteristics and mechanisms in silicon oxide memory devices

    Science.gov (United States)

    Chang, Yao-Feng; Fowler, Burt; Chen, Ying-Chen; Zhou, Fei; Wu, Xiaohan; Chen, Yen-Ting; Wang, Yanzhen; Xue, Fei; Lee, Jack C.

    2016-05-01

    Intrinsic unipolar SiOx-based resistance random access memories (ReRAM) characterization, switching mechanisms, and applications have been investigated. Device structures, material compositions, and electrical characteristics are identified that enable ReRAM cells with high ON/OFF ratio, low static power consumption, low switching power, and high readout-margin using complementary metal-oxide semiconductor transistor (CMOS)-compatible SiOx-based materials. These ideas are combined with the use of horizontal and vertical device structure designs, composition optimization, electrical control, and external factors to help understand resistive switching (RS) mechanisms. Measured temperature effects, pulse response, and carrier transport behaviors lead to compact models of RS mechanisms and energy band diagrams in order to aid the development of computer-aided design for ultralarge-v scale integration. This chapter presents a comprehensive investigation of SiOx-based RS characteristics and mechanisms for the post-CMOS device era.

  12. Solution-processed low dimensional nanomaterials with self-assembled polymers for flexible photo-electronic devices (Presentation Recording)

    Science.gov (United States)

    Park, Cheolmin

    2015-09-01

    Self assembly driven by complicated but systematic hierarchical interactions offers a qualified alternative for fabricating functional micron or nanometer scale pattern structures that have been potentially useful for various organic and nanotechnological devices. Self assembled nanostructures generated from synthetic polymer systems such as controlled polymer blends, semi-crystalline polymers and block copolymers have gained a great attention not only because of the variety of nanostructures they can evolve but also because of the controllability of these structures by external stimuli. In this presentation, various novel photo-electronic materials and devices are introduced based on the solution-processed low dimensional nanomaterials such as networked carbon nanotubes (CNTs), reduced graphene oxides (rGOs) and 2 dimensional transition metal dichalcogenides (TMDs) with self assembled polymers including field effect transistor, electroluminescent device, non-volatile memory and photodetector. For instance, a nanocomposite of networked CNTs and a fluorescent polymer turned out an efficient field induced electroluminescent layer under alternating current (AC) as a potential candidate for next generation displays and lightings. Furthermore, scalable and simple strategies employed for fabricating rGO as well as TMD nanohybrid films allowed for high performance and mechanically flexible non-volatile resistive polymer memory devices and broad band photo-detectors, respectively.

  13. Flexible pipe crawling device having articulated two axis coupling

    Science.gov (United States)

    Zollinger, William T.

    1994-01-01

    An apparatus for moving through the linear and non-linear segments of piping systems. The apparatus comprises a front leg assembly, a rear leg assembly, a mechanism for extension and retraction of the front and rear leg assembles with respect to each other, such as an air cylinder, and a pivoting joint. One end of the flexible joint attaches to the front leg assembly and the other end to the air cylinder, which is also connected to the rear leg assembly. The air cylinder allows the front and rear leg assemblies to progress through a pipe in "inchworm" fashion, while the joint provides the flexibility necessary for the pipe crawler to negotiate non-linear piping segments. The flexible connecting joint is coupled with a spring-force suspension system that urges alignment of the front and rear leg assemblies with respect to each other. The joint and suspension system cooperate to provide a firm yet flexible connection between the front and rear leg assemblies to allow the pivoting of one with respect to the other while moving around a non-linear pipe segment, but restoring proper alignment coming out of the pipe bend.

  14. Self-assembled nanostructured resistive switching memory devices fabricated by templated bottom-up growth.

    Science.gov (United States)

    Song, Ji-Min; Lee, Jang-Sik

    2016-01-07

    Metal-oxide-based resistive switching memory device has been studied intensively due to its potential to satisfy the requirements of next-generation memory devices. Active research has been done on the materials and device structures of resistive switching memory devices that meet the requirements of high density, fast switching speed, and reliable data storage. In this study, resistive switching memory devices were fabricated with nano-template-assisted bottom up growth. The electrochemical deposition was adopted to achieve the bottom-up growth of nickel nanodot electrodes. Nickel oxide layer was formed by oxygen plasma treatment of nickel nanodots at low temperature. The structures of fabricated nanoscale memory devices were analyzed with scanning electron microscope and atomic force microscope (AFM). The electrical characteristics of the devices were directly measured using conductive AFM. This work demonstrates the fabrication of resistive switching memory devices using self-assembled nanoscale masks and nanomateirals growth from bottom-up electrochemical deposition.

  15. Adhesive flexible barrier film, method of forming same, and organic electronic device including same

    Science.gov (United States)

    Blizzard, John Donald; Weidner, William Kenneth

    2013-02-05

    An adhesive flexible barrier film comprises a substrate and a barrier layer disposed on the substrate. The barrier layer is formed from a barrier composition comprising an organosilicon compound. The adhesive flexible barrier film also comprises an adhesive layer disposed on the barrier layer and formed from an adhesive composition. A method of forming the adhesive flexible barrier film comprises the steps of disposing the barrier composition on the substrate to form the barrier layer, disposing the adhesive composition on the barrier layer to form the adhesive layer, and curing the barrier layer and the adhesive layer. The adhesive flexible barrier film may be utilized in organic electronic devices.

  16. Investigation of mechanical bending instability in flexible low-temperature-processed electrochromic display devices

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Chin-Pao; Chou, Chuan-Pu; Hsu, Che-Hsiang; Teng, Tun-Chien; Cheng, Chun-Hu, E-mail: chcheng@ntnu.edu.tw; Syu, Yu-Yang

    2015-06-01

    In this study, polyethylene naphthalate (PEN) was investigated as a flexible substrate because, compared with polyethylene terephthalate, it achieves a lower root mean square roughness and transmittance, which is favorable for reducing leakage from the bottom of flexible substrates. A flexible device structure composed of tungsten oxide/indium-doped tin oxide/PEN was used in an electrochromic (EC) test. The experimental results show that the flexible EC display device achieved a high transmittance difference of > 40% and color efficiency of 70.2 cm{sup 2}/C at 560 nm. The transmittance difference was degraded in the visible range after 200 cycles of continuous bending. Furthermore, compared with flat fresh devices, the WO{sub 3} device exhibited poor retention properties in a colored state after being subjected to longer bending cycles. - Highlights: • Flexible electrochromic device with endurance bending was demonstrated. • Interface defects or vacancies near the flexible substrate affect the self-bleaching behavior. • High color efficiency of 117.2 cm{sup 2}/coul at 700 nm wavelength is reached. • Interface defect centers lower the redox energy barrier which reduces the bleaching time.

  17. Shape memory alloy-based biopsy device for active locomotive intestinal capsule endoscope.

    Science.gov (United States)

    Le, Viet Ha; Hernando, Leon-Rodriguez; Lee, Cheong; Choi, Hyunchul; Jin, Zhen; Nguyen, Kim Tien; Go, Gwangjun; Ko, Seong-Young; Park, Jong-Oh; Park, Sukho

    2015-03-01

    Recently, capsule endoscopes have been used for diagnosis in digestive organs. However, because a capsule endoscope does not have a locomotive function, its use has been limited to small tubular digestive organs, such as small intestine and esophagus. To address this problem, researchers have begun studying an active locomotive intestine capsule endoscope as a medical instrument for the whole gastrointestinal tract. We have developed a capsule endoscope with a small permanent magnet that is actuated by an electromagnetic actuation system, allowing active and flexible movement in the patient's gut environment. In addition, researchers have noted the need for a biopsy function in capsule endoscope for the definitive diagnosis of digestive diseases. Therefore, this paper proposes a novel robotic biopsy device for active locomotive intestine capsule endoscope. The proposed biopsy device has a sharp blade connected with a shape memory alloy actuator. The biopsy device measuring 12 mm in diameter and 3 mm in length was integrated into our capsule endoscope prototype, where the device's sharp blade was activated and exposed by the shape memory alloy actuator. Then the electromagnetic actuation system generated a specific motion of the capsule endoscope to extract the tissue sample from the intestines. The final biopsy sample tissue had a volume of about 6 mm(3), which is a sufficient amount for a histological analysis. Consequently, we proposed the working principle of the biopsy device and conducted an in-vitro biopsy test to verify the feasibility of the biopsy device integrated into the capsule endoscope prototype using the electro-magnetic actuation system. © IMechE 2015.

  18. Enhanced organic memory devices (OMEM) with a photochromic perhydro DTE as a transduction layer (Conference Presentation)

    Science.gov (United States)

    Cordes, Sandra; Kranz, Darius; Maibach, Eduard; Kempf, Maxim; Meerholz, Klaus

    2016-09-01

    In modern electronic systems memory elements are of fundamental importance for data storage. Especially solution-processable nonvolatile organic memories, which are inexpensive and can be manufactured on flexible substrates, are a promising alternative to brittle inorganic devices. Organic photochromic switchable compounds, mostly dithienylethenes (DTEs), are thermally stable, fatigue resistant and can undergo an electrically- or/and photo-induced ring-opening and -closing reaction which results in a change of energy levels. Due to the energetic difference in the highest occupied molecular orbital (HOMO) between the open and closed isomer, the DTE layer can be exploited as a switchable hole injection barrier that controls the electrical current in the diode. We demonstrated that a light-emitting organic memory (LE-OMEM) device with a perfluoro DTE transduction layer can be switched electrically via high current densities pulses and optically by irradiated light, with impressive current ON/OFF Ratios (OOR) of 10Λ2, 10Λ4 respectively. Currently we aim to minimize the barrier of the ON state and maximize the barrier of the OFF state by designing DTE molecules with larger differences in the HOMO energies of the two isomers yielding improved OOR values. By synthesizing perhydro derivates of DTE we achieved molecules with high HOMO levels and large ΔHOMO energies providing OMEM devices with excellent physical properties (OOR 1.4 x higher than perfluoro DTE). Due to the high HOMO level of the perhydro DTE utilization of hole transport layers (HTLs) is not necessary and thus manufacturing of OMEM devices is simplified.

  19. Topology optimization of flexible micro-fluidic devices

    DEFF Research Database (Denmark)

    Kreissl, Sebastian; Pingen, Georg; Evgrafov, Anton;

    2010-01-01

    A multi-objective topology optimization formulation for the design of dynamically tunable fluidic devices is presented. The flow is manipulated via external and internal mechanical actuation, leading to elastic deformations of flow channels. The design objectives characterize the performance...

  20. Apparatus And Method Of Using Flexible Printed Circuit Board In Optical Transceiver Device

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Gene R. (Albuquerque, NM); Armendariz, Marcelino G. (Albuquerque, NM); Bryan, Robert P. (Albuquerque, NM); Carson, Richard F. (Albuquerque, NM); Duckett, III, Edwin B. (Albuquerque, NM); McCormick, Frederick B. (Albuquerque, NM); Peterson, David W. (Sandia Park, NM); Peterson, Gary D. (Albuquerque, NM); Reysen, Bill H. (Lafayette, CO)

    2005-03-15

    This invention relates to a flexible printed circuit board that is used in connection with an optical transmitter, receiver or transceiver module. In one embodiment, the flexible printed circuit board has flexible metal layers in between flexible insulating layers, and the circuit board comprises: (1) a main body region orientated in a first direction having at least one electrical or optoelectronic device; (2) a plurality of electrical contact pads integrated into the main body region, where the electrical contact pads function to connect the flexible printed circuit board to an external environment; (3) a buckle region extending from one end of the main body region; and (4) a head region extending from one end of the buckle region, and where the head region is orientated so that it is at an angle relative to the direction of the main body region. The electrical contact pads may be ball grid arrays, solder balls or land-grid arrays, and they function to connect the circuit board to an external environment. A driver or amplifier chip may be adapted to the head region of the flexible printed circuit board. In another embodiment, a heat spreader passes along a surface of the head region of the flexible printed circuit board, and a window is formed in the head region of the flexible printed circuit board. Optoelectronic devices are adapted to the head spreader in such a manner that they are accessible through the window in the flexible printed circuit board.

  1. Flexible molecular-scale electronic devices composed of diarylethene photoswitching molecules

    KAUST Repository

    Kim, Dongku

    2014-03-31

    The electrical properties of diarylethene photoswitching molecular devices on flexible substrates are studied. When exposed to UV or visible light, diarylethene molecular devices show two electrical states (a high and a low conductance state) with a discrepancy of an order of magnitude in the level of current between the two states. The diarylethene flexible molecular devices exhibit excellent long-time stability and reliable electrical characteristics in both conductance states when subjected to various mechanical stresses. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. A Silicon-Based Ferroelectric Capacitor for Memory Devices

    Institute of Scientific and Technical Information of China (English)

    任天令; 张林涛; 刘理天; 李志坚

    2002-01-01

    We study a silicon-based Pb TiO3/Pb(Zro.53 Tio.47)O3/Pb TiO3 capacitor, prepared by an improved sol-gel method.The ferroelectric capacitor has a high remanent polarization of 15 pC/crm2 at a coercive field of about 30 k V/cm,an ultra-low leakage current density of 0.1 hA/crm2, and almost fatigue free properties. It can be used as a promising candidate for ferroelectric memory devices.

  3. Flexible Display and Integrated Communication Devices (FDICD) Technology. Volume 2

    Science.gov (United States)

    2008-06-01

    David Huffman, Keith Tognoni, Robert Anderson, Michael Hack , Anna Chwang, Richard Hewitt, Robert A. Street, Jackson Ho, JengPing Lu, and Darrel G...Anderson, Michael Hack , Anna Chwang, Richard Hewitt, Robert A. Street, Jackson Ho, JengPing Lu, and Darrel G. Hopper, “Flexible Display and...fabric covering; tethered stylus; Bluetooth, WiFi 802.11b&g; Windows Mobile 5.0; and touchscreen. Ten (10) units of this spiral (Spiral 3.0) will be

  4. Selected Advances in Nanoelectronic Devices Logic, Memory and RF

    CERN Document Server

    Joodaki, Mojtaba

    2013-01-01

    Nanoelectronics, as a true successor of microelectronics, is certainly a major technology boomer in the 21st century. This has been shown by its several applications and also by its enormous potential to influence all areas of electronics, computers, information technology, aerospace defense, and consumer goods. Although the current semiconductor technology is projected to reach its physical limit in about a decade, nanoscience and nanotechnology promise breakthroughs for the future. The present books provides an in-depth review of the latest advances in the technology of nanoelectronic devices and their developments over the past decades. Moreover, it introduces new concepts for the realization of future nanoelectronic devices. The main focus of the book is on three fundamental branches of semiconductor products or applications: logic, memory, and RF and communication. By pointing out to the key technical challenges, important aspects and characteristics of various designs are used to illustrate mechanisms t...

  5. Flexible semi-transparent silicon (100) fabric with high-k/metal gate devices

    KAUST Repository

    Rojas, Jhonathan Prieto

    2013-01-07

    Can we build a flexible and transparent truly high performance computer? High-k/metal gate stack based metal-oxide-semiconductor capacitor devices are monolithically fabricated on industry\\'s most widely used low-cost bulk single-crystalline silicon (100) wafers and then released as continuous, mechanically flexible, optically semi-transparent and high thermal budget compatible silicon fabric with devices. This is the first ever demonstration with this set of materials which allows full degree of freedom to fabricate nanoelectronics devices using state-of-the-art CMOS compatible processes and then to utilize them in an unprecedented way for wide deployment over nearly any kind of shape and architecture surfaces. Electrical characterization shows uncompromising performance of post release devices. Mechanical characterization shows extra-ordinary flexibility (minimum bending radius of 1 cm) making this generic process attractive to extend the horizon of flexible electronics for truly high performance computers. Schematic and photograph of flexible high-k/metal gate MOSCAPs showing high flexibility and C-V plot showing uncompromised performance. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Flexible and stretchable electronics for wearable health devices

    NARCIS (Netherlands)

    Brand, J. van den; Kok, M. de; Koetse, M.; Cauwe, M.; Verplancke, R.; Bossuyt, F.; Jablonski, M.; Vanfleteren, J.

    2015-01-01

    Measuring the quality of human health and well-being is one of the key growth areas in our society. Preferably, these measurements are done as unobtrusive as possible. These sensoric devices are then to be integrated directly on the human body as a patch or integrated into garments. This requires th

  7. Novel nano materials for high performance logic and memory devices

    Science.gov (United States)

    Das, Saptarshi

    After decades of relentless progress, the silicon CMOS industry is approaching a stall in device performance for both logic and memory devices due to fundamental scaling limitations. In order to reinforce the accelerating pace, novel materials with unique properties are being proposed on an urgent basis. This list includes one dimensional nanotubes, quasi one dimensional nanowires, two dimensional atomistically thin layered materials like graphene, hexagonal boron nitride and the more recently the rich family of transition metal di-chalcogenides comprising of MoS2, WSe2, WS2 and many more for logic applications and organic and inorganic ferroelectrics, phase change materials and magnetic materials for memory applications. Only time will tell who will win, but exploring these novel materials allow us to revisit the fundamentals and strengthen our understanding which will ultimately be beneficial for high performance device design. While there has been growing interest in two-dimensional (2D) crystals other than graphene, evaluating their potential usefulness for electronic applications is still in its infancies due to the lack of a complete picture of their performance potential. The fact that the 2-D layered semiconducting di-chalcogenides need to be connected to the "outside" world in order to capitalize on their ultimate potential immediately emphasizes the importance of a thorough understanding of the contacts. This thesis demonstrate that through a proper understanding and design of source/drain contacts and the right choice of number of MoS2 layers the excellent intrinsic properties of this 2D material can be harvested. A comprehensive experimental study on the dependence of carrier mobility on the layer thickness of back gated multilayer MoS 2 field effect transistors is also provided. A resistor network model that comprises of Thomas-Fermi charge screening and interlayer coupling is used to explain the non-monotonic trend in the extracted field effect

  8. UV-nanoimprint lithography as a tool to develop flexible microfluidic devices for electrochemical detection.

    Science.gov (United States)

    Chen, Juhong; Zhou, Yiliang; Wang, Danhui; He, Fei; Rotello, Vincent M; Carter, Kenneth R; Watkins, James J; Nugen, Sam R

    2015-07-21

    Research in microfluidic biosensors has led to dramatic improvements in sensitivities. Very few examples of these devices have been commercially successful, keeping this methodology out of the hands of potential users. In this study, we developed a method to fabricate a flexible microfluidic device containing electrowetting valves and electrochemical transduction. The device was designed to be amenable to a roll-to-roll manufacturing system, allowing a low manufacturing cost. Microchannels with high fidelity were structured on a PET film using UV-NanoImprint Lithography (UV-NIL). The electrodes were inkjet-printed and photonically sintered on second flexible PET film. The film containing electrodes was bonded directly to the channel-containing layer to form sealed fluidic device. Actuation of the multivalve system with food dye in PBS buffer was performed to demonstrate automated fluid delivery. The device was then used to detect Salmonella in a liquid sample.

  9. Low-cost rapid prototyping of flexible plastic paper based microfluidic devices

    KAUST Repository

    Fan, Yiqiang

    2013-04-01

    This research presents a novel rapid prototyping method for paper-based flexible microfluidic devices. The microchannels were fabricated using laser ablation on a piece of plastic paper (permanent paper), the dimensions of the microchannels was carefully studied for various laser powers and scanning speeds. After laser ablation of the microchannels on the plastic paper, a transparent poly (methyl methacrylate)(PMMA) film was thermally bonded to the plastic paper to enclose the channels. After connection of tubing, the device was ready to use. An example microfluidic device (droplet generator) was also fabricated using this technique. Due to the flexibility of the fabricated device, this technique can be used to fabricate 3D microfluidic devices. The fabrication process was simple and rapid without any requirement of cleanroom facilities. © 2013 IEEE.

  10. Flexibility.

    Science.gov (United States)

    Humphrey, L. Dennis

    1981-01-01

    Flexibility is an important aspect of all sports and recreational activities. Flexibility can be developed and maintained by stretching exercises. Exercises designed to develop flexibility in ankle joints, knees, hips, and the lower back are presented. (JN)

  11. Fully transparent, non-volatile bipolar resistive memory based on flexible copolyimide films

    Science.gov (United States)

    Yu, Hwan-Chul; Kim, Moon Young; Hong, Minki; Nam, Kiyong; Choi, Ju-Young; Lee, Kwang-Hun; Baeck, Kyoung Koo; Kim, Kyoung-Kook; Cho, Soohaeng; Chung, Chan-Moon

    2017-01-01

    Partially aliphatic homopolyimides and copolyimides were prepared from rel-(1'R,3S,5'S)-spiro[furan-3(2H),6'-[3]oxabicyclo[3.2.1]octane]-2,2',4',5(4H)-tetrone (DAn), 2,6-diaminoanthracene (AnDA), and 4,4'-oxydianiline (ODA) by varying the molar ratio of AnDA and ODA. We utilized these polyimide films as the resistive switching layer in transparent memory devices. While WORM memory behavior was obtained with the PI-A100-O0-based device (molar feed ratio of DAn : AnDA : ODA = 1 : 1 : 0), the PI-A70-O30-based device (molar feed ratio of DAn : AnDA : ODA = 1 : 0.7 : 0.3) exhibited bipolar resistive switching behavior with stable retention for 104 s. This result implies that the memory properties can be controlled by changing the polyimide composition. The two devices prepared from PI-A100-O0 and PI-A70-O30 showed over 90% transmittance in the visible wavelength range from 400 to 800 nm. The behavior of the memory devices is considered to be governed by trap-controlled, space-charge limited conduction (SCLC) and local filament formation. [Figure not available: see fulltext.

  12. Flexible Surface Acoustic Wave Device with AlN Film on Polymer Substrate

    Directory of Open Access Journals (Sweden)

    Jian Zhou

    2012-01-01

    Full Text Available Surface acoustic wave device with c-axis-oriented aluminum nitride (AlN piezoelectric thin films on polymer substrates can be potentially used for development of flexible sensors, flexible microfluidic applications, microsystems, and lab-on-chip systems. In this work, the AlN films have been successfully deposited on polymer substrates using the DC reactive magnetron-sputtering method at room temperature, and the XRD, SEM, and AFM methods reveal that low deposition pressure is beneficial to the highly c-axis-oriented AlN film on polymer substrates. Studies toward the development of AlN thin film-based flexible surface acoustic wave devices on the polymer substrates are initiated and the experimental and simulated results demonstrate the devices showing the acoustic wave velocity of 9000–10000 m/s, which indicate the AlN lamb wave.

  13. Flexible barrier film, method of forming same, and organic electronic device including same

    Science.gov (United States)

    Blizzard, John; Tonge, James Steven; Weidner, William Kenneth

    2013-03-26

    A flexible barrier film has a thickness of from greater than zero to less than 5,000 nanometers and a water vapor transmission rate of no more than 1.times.10.sup.-2 g/m.sup.2/day at 22.degree. C. and 47% relative humidity. The flexible barrier film is formed from a composition, which comprises a multi-functional acrylate. The composition further comprises the reaction product of an alkoxy-functional organometallic compound and an alkoxy-functional organosilicon compound. A method of forming the flexible barrier film includes the steps of disposing the composition on a substrate and curing the composition to form the flexible barrier film. The flexible barrier film may be utilized in organic electronic devices.

  14. Highly flexible peeled-off silver nanowire transparent anode using in organic light-emitting devices

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Ya-Hui; Duan, Yu, E-mail: duanyu@jlu.edu.cn; Wang, Xiao; Yang, Dan; Yang, Yong-Qiang; Chen, Ping; Sun, Feng-Bo; Xue, Kai-Wen; Zhao, Yi

    2015-10-01

    Graphical abstract: - Highlights: • An ultra-smooth AgNW film on a flexible photopolymer substrate has been fabricated. • The AgNW film has a low sheet resistance with high transparency and flexibility. • OLEDs based on AgNW:NOA63 substrate can be bent at a radius of curvature of 2 mm. - Abstract: Materials to replace indium tin oxide (ITO) for high transmittance and electrical conductivity are urgently needed. In this paper, we adopted a silver nanowire (AgNW)-photopolymer (NOA63) film as a new platform for flexible optoelectronic devices. This design combined a transparent electrode and a flexible substrate. We utilized this application to obtain flexible organic light-emitting devices (FOLEDs). A peel-off process combined with a spin-coating process created an ultra-smooth silver nanowire anode on a photopolymer substrate. The performance of the device was achieved via the perfect morphology of the AgNW anode, the optimal 5 mg/ml concentration of AgNW solution, and the 45.7 Ω/□ sheet resistance of the AgNW film. The maximum current efficiency of the FOLED is 13 cd/A with stable mechanical flexibility even when bent to a radius of curvature of 2 mm. The outstanding performance of the FOLED with peeled off AgNW anode shows that this approach is a promising alternative to ITO for FOLEDs.

  15. Scaling dependence of memory windows and different carrier charging behaviors in Si nanocrystal nonvolatile memory devices

    Science.gov (United States)

    Yu, Jie; Chen, Kun-ji; Ma, Zhong-yuan; Zhang, Xin-xin; Jiang, Xiao-fan; Wu, Yang-qing; Huang, Xin-fan; Oda, Shunri

    2016-09-01

    Based on the charge storage mode, it is important to investigate the scaling dependence of memory performance in silicon nanocrystal (Si-NC) nonvolatile memory (NVM) devices for its scaling down limit. In this work, we made eight kinds of test key cells with different gate widths and lengths by 0.13-μm node complementary metal oxide semiconductor (CMOS) technology. It is found that the memory windows of eight kinds of test key cells are almost the same of about 1.64 V @ ± 7 V/1 ms, which are independent of the gate area, but mainly determined by the average size (12 nm) and areal density (1.8 × 1011/cm2) of Si-NCs. The program/erase (P/E) speed characteristics are almost independent of gate widths and lengths. However, the erase speed is faster than the program speed of test key cells, which is due to the different charging behaviors between electrons and holes during the operation processes. Furthermore, the data retention characteristic is also independent of the gate area. Our findings are useful for further scaling down of Si-NC NVM devices to improve the performance and on-chip integration. Project supported by the State Key Development Program for Basic Research of China (Grant No. 2010CB934402) and the National Natural Science Foundation of China (Grant Nos. 11374153, 61571221, and 61071008).

  16. Flexible Substrate-Based Devices for Point-of-Care Diagnostics.

    Science.gov (United States)

    Wang, ShuQi; Chinnasamy, Thiruppathiraja; Lifson, Mark A; Inci, Fatih; Demirci, Utkan

    2016-11-01

    Point-of-care (POC) diagnostics play an important role in delivering healthcare, particularly for clinical management and disease surveillance in both developed and developing countries. Currently, the majority of POC diagnostics utilize paper substrates owing to affordability, disposability, and mass production capability. Recently, flexible polymer substrates have been investigated due to their enhanced physicochemical properties, potential to be integrated into wearable devices with wireless communications for personalized health monitoring, and ability to be customized for POC diagnostics. Here, we focus on the latest advances in developing flexible substrate-based diagnostic devices, including paper and polymers, and their clinical applications.

  17. An electrolyte-free flexible electrochromic device using electrostatically strong graphene quantum dot-viologen nanocomposites.

    Science.gov (United States)

    Hwang, Eunhee; Seo, Sohyeon; Bak, Sora; Lee, Hanleem; Min, Misook; Lee, Hyoyoung

    2014-08-13

    A strong electrostatic MV(2+) -GQD nanocomposite provides an electrolyte-free flexible electrochromic device wih high durability. The positively charged MV(2+) and negatively charged GQD are strongly stabilized by non-covalent intermolecular forces (e.g., electrostatic interactions, π-π stacking interactions, and cation-π electron interactions), eliminating the need for an electrolyte. An electrolyte-free flexible electrochromic device fabricated from the GQD-supported MV(2+) exhibits stable performance under mechanical and thermal stresses. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. An annulus fibrosus closure device based on a biodegradable shape-memory polymer network.

    Science.gov (United States)

    Sharifi, Shahriar; van Kooten, Theo G; Kranenburg, Hendrik-Jan C; Meij, Björn P; Behl, Marc; Lendlein, Andreas; Grijpma, Dirk W

    2013-11-01

    Injuries to the intervertebral disc caused by degeneration or trauma often lead to tearing of the annulus fibrosus (AF) and extrusion of the nucleus pulposus (NP). This can compress nerves and cause lower back pain. In this study, the characteristics of poly(D,L-lactide-co-trimethylene carbonate) networks with shape-memory properties have been evaluated in order to prepare biodegradable AF closure devices that can be implanted minimally invasively. Four different macromers with (D,L-lactide) to trimethylene carbonate (DLLA:TMC) molar ratios of 80:20, 70:30, 60:40 and 40:60 with terminal methacrylate groups and molecular weights of approximately 30 kg mol(-1) were used to prepare the networks by photo-crosslinking. The mechanical properties of the samples and their shape-memory properties were determined at temperatures of 0 °C and 40 °C by tensile tests- and cyclic, thermo-mechanical measurements. At 40 °C all networks showed rubber-like behavior and were flexible with elastic modulus values of 1.7-2.5 MPa, which is in the range of the modulus values of human annulus fibrosus tissue. The shape-memory characteristics of the networks were excellent with values of the shape-fixity and the shape-recovery ratio higher than 98 and 95%, respectively. The switching temperatures were between 10 and 39 °C. In vitro culture and qualitative immunocytochemistry of human annulus fibrosus cells on shape-memory films with DLLA:TMC molar ratios of 60:40 showed very good ability of the networks to support the adhesion and growth of human AF cells. When the polymer network films were coated by adsorption of fibronectin, cell attachment, cell spreading, and extracellular matrix production was further improved. Annulus fibrosus closure devices were prepared from these AF cell-compatible materials by photo-polymerizing the reactive precursors in a mold. Insertion of the multifunctional implant in the disc of a cadaveric canine spine showed that these shape-memory devices could be

  19. All-inkjet-printed flexible ZnO micro photodetector for a wearable UV monitoring device

    Science.gov (United States)

    Tran, Van-Thai; Wei, Yuefan; Yang, Hongyi; Zhan, Zhaoyao; Du, Hejun

    2017-03-01

    Fabrication of small-sized patterns of inorganic semiconductor onto flexible substrates is a major concern when manufacturing wearable devices for measuring either biometric or environmental parameters. In this study, micro-sized flexible ZnO UV photodetectors have been thoroughly prepared by a facile inkjet printing technology and followed with heat treatments. A simple ink recipe of zinc acetate precursor solution was investigated. It is found that the substrate temperature during zinc precursor ink depositing has significant effects on ZnO pattern shape, film morphology, and crystallization. The device fabricated from the additive manufacturing approach has good bendability, Ohmic contact, short response time as low as 0.3 s, and high on/off ratio of 3525. We observed the sensor’s dependence of response/decay time by the illuminating UV light intensity. The whole process is based on additive manufacturing which has many benefits such as rapid prototyping, saving material, being environmentally friendly, and being capable of creating high-resolution patterns. In addition, this method can be applied to flexible substrates, which makes the device more applicable for applications requiring flexibility such as wearable devices. The proposed all-inkjet-printing approach for a micro-sized ZnO UV photodetector would significantly simplify the fabrication process of micro-sized inorganic semiconductor-based devices. A potential application is real-time monitoring of UV light exposure to warn users about unsafe direct sunlight to implement suitable avoidance solutions.

  20. Memory for reputational trait information: is social-emotional information processing less flexible in old age?

    Science.gov (United States)

    Bell, Raoul; Giang, Trang; Mund, Iris; Buchner, Axel

    2013-12-01

    How do younger and older adults remember reputational trait information about other people? In the present study, trustworthy-looking and untrustworthy-looking faces were paired with cooperation or cheating in a cooperation game. In a surprise source-memory test, participants were asked to rate the likability of the faces, and were required to remember whether the faces were associated with negative or positive outcomes. The social expectations of younger and older adults were clearly affected by a priori facial trustworthiness. Facial trustworthiness was associated with high cooperation-game investments, high likability ratings, and a tendency toward guessing that a face belonged to a cooperator instead of a cheater in both age groups. Consistent with previous results showing that emotional memory is spared from age-related decline, memory for the association between faces and emotional reputational information was well preserved in older adults. However, younger adults used a flexible encoding strategy to remember the social interaction partners. Source-memory was best for information that violated their (positive) expectations. Older adults, in contrast, showed a uniform memory bias for negative social information; their memory performance was not modulated by their expectations. This finding suggests that older adults are less likely to adjust their encoding strategies to their social expectations than younger adults. This may be in line with older adults' motivational goals to avoid risks in social interactions.

  1. Ultra-flexible Piezoelectric Devices Integrated with Heart to Harvest the Biomechanical Energy.

    Science.gov (United States)

    Lu, Bingwei; Chen, Ying; Ou, Dapeng; Chen, Hang; Diao, Liwei; Zhang, Wei; Zheng, Jun; Ma, Weiguo; Sun, Lizhong; Feng, Xue

    2015-11-05

    Power supply for medical implantable devices (i.e. pacemaker) always challenges not only the surgery but also the battery technology. Here, we report a strategy for energy harvesting from the heart motion by using ultra-flexible piezoelectric device based on lead zirconate titanate (PZT) ceramics that has most excellent piezoelectricity in commercial materials, without any burden or damage to hearts. Experimental swine are selected for in vivo test with different settings, i.e. opened chest, close chest and awake from anesthesia, to simulate the scenario of application in body due to their hearts similar to human. The results show the peak-to-peak voltage can reach as high as 3 V when the ultra-flexible piezoelectric device is fixed from left ventricular apex to right ventricle. This demonstrates the possibility and feasibility of fully using the biomechanical energy from heart motion in human body for sustainably driving implantable devices.

  2. In-Plane Bistable Nanowire For Memory Devices

    CERN Document Server

    Charlot, B; Yamashita, K; Fujita, H; Toshiyoshi, H

    2008-01-01

    We present a nanomechanical device design to be used in a non-volatile mechanical memory point. The structure is composed of a suspended slender nanowire (width : 100nm, thickness 430nm length : 8 to 30$\\mu$m) clamped at its both ends. Electrodes are placed on each sides of the nanowire and are used to actuate the structure (writing, erasing) and to measure the position through a capactive bridge (reading). The structure is patterned by electron beam lithography on a pre-stressed thermally grown silicon dioxide layer. When later released, the stressed material relaxes and the beam buckles in a position of lower energy. Such symmetric beams, called Euler beams, show two stable deformed positions thus form a bistable structure. This paper will present the fabrication, simulation and mechanical and electrical actuation of an in plane bistable nanowire. Final paper will include a section on FEM simulations.

  3. Fundamental display properties of flexible devices containing polymer-stabilized ferroelectric liquid crystal between plastic substrates

    Science.gov (United States)

    Fujikake, Hideo; Murashige, Takeshi; Sato, Hiroto; Iino, Yoshiki; Kawakita, Masahiro; Kikuchi, Hiroshi

    2002-09-01

    We describe several fundamental display properties of a flexible ferroelectric liquid crystal device containing polymer fibers between thin plastic substrates. The composite film of liquid crystal and polymer was created from a solution of liquid crystal and monomer materials between the plastic substrates under ultraviolet light irradiation. The dynamic electrooptic response to analog voltage pulses was examined with an incidence of laser beam light, and its light modulation property exhibited good linearity in continuous gray-scale capability. The excellent spatial uniformity of liquid crystal alignment formed between the flexible substrates resulted in high-contrast light modulation, although slight spontaneous bending of liquid crystal alignment in the device plane was recognized. When the laser light beam was obliquely incident on the flexible display device, the measured transmittance revealed that the device has a wide viewing angle of more than 100 deg without contrast reversal. This is considered to be caused by the molecular switching in the device plane and the thin electrooptic layer in the display device.

  4. Bending induced electrical response variations in ultra-thin flexible chips and device modeling

    Science.gov (United States)

    Heidari, Hadi; Wacker, Nicoleta; Dahiya, Ravinder

    2017-09-01

    Electronics that conform to 3D surfaces are attracting wider attention from both academia and industry. The research in the field has, thus far, focused primarily on showcasing the efficacy of various materials and fabrication methods for electronic/sensing devices on flexible substrates. As the device response changes are bound to change with stresses induced by bending, the next step will be to develop the capacity to predict the response of flexible systems under various bending conditions. This paper comprehensively reviews the effects of bending on the response of devices on ultra-thin chips in terms of variations in electrical parameters such as mobility, threshold voltage, and device performance (static and dynamic). The discussion also includes variations in the device response due to crystal orientation, applied mechanics, band structure, and fabrication processes. Further, strategies for compensating or minimizing these bending-induced variations have been presented. Following the in-depth analysis, this paper proposes new mathematical relations to simulate and predict the device response under various bending conditions. These mathematical relations have also been used to develop new compact models that have been verified by comparing simulation results with the experimental values reported in the recent literature. These advances will enable next generation computer-aided-design tools to meet the future design needs in flexible electronics.

  5. The Innovated Flexible Surface Acoustic Wave Devices on Fully InkJet Printing Technology

    Directory of Open Access Journals (Sweden)

    Cha’o-Kuang Chen

    2013-09-01

    Full Text Available An innovated fabricated process of the flexible surface acoustic wave (SAW device is proposed in this study. Fully inkjet printing and sol-gel technology are used in this fabricated process. The flexible SAW device is composed of a ZnO layer sandwiched in between a flexible polyimide plastic sheet and two sets of interdigital transducers layer. The material of the top interdigital transducer layer is nano silver. The ZnO solution is prepared by sol-gel technology. Both the ZnO and top interdigital transducer layers are deposited by inkjet printing. The fully inkjet printing process possesses the advantages of direct patterning and low-cost. It does not require photolithography and etching processes since the pattern is directly printed on the flexible sheet. The center frequency of this prototype is matched with the design frequency. The prototype demonstrates that the presented flexible SAW device is available for the possible application in future. It may be applied to the sensing on curve surface.

  6. Tribo-Mechanical Investigation of the Functional Components used in Flexible Energy Harvesting Devices

    Science.gov (United States)

    Morris, Nicholas J.

    During the previous decade, the development of energy harvesting devices based on piezoelectric materials has garnered great interest. The ability to capture ambient mechanical energy and convert it to useable electricity is a potential solution to the ever-growing energy crisis. One of the most attractive functional materials used in these devices is zinc oxide (ZnO). This material's relative low cost and ease of large-area processing has spurred numerous device designs based around it. The ability to grow ZnO nanostructures of various geometries with low-temperature chemical methods makes this material even more attractive for flexible devices. Although numerous device architectures have been developed, the long-term mechanical reliability has not been addressed. This work focuses on the fabrication and mechanical failure analysis of the flexible components typically used in piezoelectric energy harvesting devices. A three-phase iterative design process was used to fabricate prototypical piezoelectric nanogenerators, based on ZnO nanowires. An output of several millivolts was achieved under normal contact and microtensile loading, but device failure occurred after only a few loading cycles, in all cases. Ex situ failure analysis confirmed the primary sources of failure, which became the focus of further, component-level studies. Failure was primarily seen in the flexible electrodes of the nanogenerating devices, but was also observed in the functional piezoelectric layer itself. Flexible electrodes comprised of polyester substrates with transparent conductive oxide (TCO) coatings were extensively investigated under various loading scenarios to mimic tribo-mechanical stresses applied during fabrication and use in flexible contact-based devices. The durability of these films was explored using microtensile testing, spherical nanoindentation, controlled mechanical buckling, stress corrosion cracking, and shear-contact reciprocating wear. The electro

  7. Solid state MEMS devices on flexible and semi-transparent silicon (100) platform

    KAUST Repository

    Ahmed, Sally

    2014-01-01

    We report fabrication of MEMS thermal actuators on flexible and semi-transparent silicon fabric released from bulk silicon (100). We fabricated the devices first and then released the top portion of the silicon (≈ 19 μm) which is flexible and semi-transparent. We also performed chemical mechanical polishing to reuse the remaining wafer. A tested thermal actuator with 3 μm wide 240 μm hot arm and 10 μm wide 185 μm long cold arm deflected by 1.7 μm at 1 V. The fabricated thermal actuators exhibit similar performance before and after bending. We believe the demonstrated process will expand the horizon of flexible electronics into MEMS world devices. © 2014 IEEE.

  8. A novel flexible drill device enabling arthroscopic transosseous repair of Bankart lesions.

    Science.gov (United States)

    Won, Y-Y; Park, J S; Choi, S J; Hong, S I

    2017-06-01

    We have developed a flexible drill device that makes arthroscopic transosseous repair possible, and report preliminary results. Twelve patients with post-traumatic anterior inferior glenohumeral instability were selected. the flexible drill device is inserted into the shoulder joint through the posterior portal and the guide pipe unit is placed 5mm posterior to the margin of the anterior glenoid rim. The flexible drill is driven through the glenoid with the power drill, creating a hole in the glenoid. A non-absorbable suture is passed through the hole and a sliding knot tying is performed over the capsule and labrum after completing stitches with the suture hook loaded. The same procedures are repeated in the 2, 3 and 4 o'clock positions of the glenoid. There was no recurrence of dislocation at the mean follow-up period of 52.3 months. The mean Rowe score was 89.5. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  9. A study on ship impacting a flexible crashworthy device for protecting bridge pier

    Directory of Open Access Journals (Sweden)

    Yang Liming

    2015-01-01

    Full Text Available As the accident of a vessel impacting a bridge pier will cause serious disaster, such as destroyed bridge, sinking ship and polluting environment, the technology and method to protect bridge pier from ship collision have been widely investigated recently. Due to the huge kinetic energy of large-tonnage ship and the short time duration in the collision, the studies involve impact mechanics. A developed flexible crashworthy device has been developed to protect bridges, which consists of an outer steel-periphery, an inner steel-periphery and the rubber coating SWRCs(soft elements installed between them. When the SWRC crashworthy device is installed, the collision duration under low impact force is prolonged due to its high compliance, which results in the ship having enough time to turn its navigation direction and most of the remainder kinetic energy being carried off by the turned away ship. Consequently, both impact forces on the ship and on the bridge pier decrease markedly. This is the key reason as to why the SWRC crashworthy device can avoid the destruction of both the bridge and the ship. Based on our results of theoretical studies and numerical simulations, the present paper will propose an experiment-adopted a real ship to impact a flexible crashworthy device. The collision test has been performed 12 times with different speed, carrying capacity, and impact angle of the ship. After the experiments, the ship, flexible crashworthy device and the pier are not damaged. The experiments show that the flexible crashworthy device can turn away the impact ship, so that the ship moves along the outer part of the device, which reduces the ship impact force on the bridge pier obviously. It not only protects bridges but also avoids the damage to ships.

  10. Khat use is associated with impaired working memory and cognitive flexibility.

    Directory of Open Access Journals (Sweden)

    Lorenza S Colzato

    Full Text Available RATIONALE: Khat consumption has increased during the last decades in Eastern Africa and has become a global phenomenon spreading to ethnic communities in the rest of the world, such as The Netherlands, United Kingdom, Canada, and the United States. Very little is known, however, about the relation between khat use and cognitive control functions in khat users. OBJECTIVE: We studied whether khat use is associated with changes in working memory (WM and cognitive flexibility, two central cognitive control functions. METHODS: Khat users and khat-free controls were matched in terms of sex, ethnicity, age, alcohol and cannabis consumption, and IQ (Raven's progressive matrices. Groups were tested on cognitive flexibility, as measured by a Global-Local task, and on WM using an N-back task. RESULT: Khat users performed significantly worse than controls on tasks tapping into cognitive flexibility as well as monitoring of information in WM. CONCLUSIONS: The present findings suggest that khat use impairs both cognitive flexibility and the updating of information in WM. The inability to monitor information in WM and to adjust behavior rapidly and flexibly may have repercussions for daily life activities.

  11. Effect of Back Contact and Rapid Thermal Processing Conditions on Flexible CdTe Device Performance

    Energy Technology Data Exchange (ETDEWEB)

    Mahabaduge, Hasitha; Meysing, D. M.; Rance, Will L.; Burst, James M.; Reese, Matthew O.; Wolden, C. A.; Gessert, Timothy A.; Metzger, Wyatt K.; Garner, S.; Barnes, Teresa M.

    2015-06-14

    Flexible CdTe solar cells on ultra-thin glass substrates can enable new applications that require high specific power, unique form-factors, and low manufacturing costs. To be successful, these cells must be cost competitive, have high efficiency, and have high reliability. Here we present back contact processing conditions that enabled us to achieve over 16% efficiency on flexible Corning (R) Willow (R) Glass substrates. We used co-evaporated ZnTe:Cu and Au as our back contact and used rapid thermal processing (RTP) to activate the back contact. Both the ZnTe to Cu ratio and the RTP activation temperature provide independent control over the device performance. We have investigated the influence of various RTP conditions to Cu activation and distribution. Current density-voltage, capacitance-voltage measurements along with device simulations were used to examine the device performance in terms of ZnTe to Cu ratio and rapid thermal activation temperature.

  12. Model for a flexible motor memory based on a self-active recurrent neural network.

    Science.gov (United States)

    Boström, Kim Joris; Wagner, Heiko; Prieske, Markus; de Lussanet, Marc

    2013-10-01

    Using recent recurrent network architecture based on the reservoir computing approach, we propose and numerically simulate a model that is focused on the aspects of a flexible motor memory for the storage of elementary movement patterns into the synaptic weights of a neural network, so that the patterns can be retrieved at any time by simple static commands. The resulting motor memory is flexible in that it is capable to continuously modulate the stored patterns. The modulation consists in an approximately linear inter- and extrapolation, generating a large space of possible movements that have not been learned before. A recurrent network of thousand neurons is trained in a manner that corresponds to a realistic exercising scenario, with experimentally measured muscular activations and with kinetic data representing proprioceptive feedback. The network is "self-active" in that it maintains recurrent flow of activation even in the absence of input, a feature that resembles the "resting-state activity" found in the human and animal brain. The model involves the concept of "neural outsourcing" which amounts to the permanent shifting of computational load from higher to lower-level neural structures, which might help to explain why humans are able to execute learned skills in a fluent and flexible manner without the need for attention to the details of the movement.

  13. Low-cost high-quality crystalline germanium based flexible devices

    KAUST Repository

    Nassar, Joanna M.

    2014-06-16

    High performance flexible electronics promise innovative future technology for various interactive applications for the pursuit of low-cost, light-weight, and multi-functional devices. Thus, here we show a complementary metal oxide semiconductor (CMOS) compatible fabrication of flexible metal-oxide-semiconductor capacitors (MOSCAPs) with high-κ/metal gate stack, using a physical vapor deposition (PVD) cost-effective technique to obtain a high-quality Ge channel. We report outstanding bending radius ~1.25 mm and semi-transparency of 30%.

  14. Highly efficient and stable cupronickel nanomesh electrode for flexible organic photovoltaic devices

    Science.gov (United States)

    Kim, Han-Jung; Song, Myungkwan; Jeong, Jun-Ho; Kim, Chang Su; Surabhi, Srivathsava; Jeong, Jong-Ryul; Kim, Dong-Ho; Choi, Dae-Geun

    2016-11-01

    Advances in flexible optoelectronic devices have led to increasing need for developing high performance, low cost, and flexible transparent conducting electrodes. Copper-based electrodes have been unattainable due to the relatively thermal instability and poor oxidation resistance. Herein, we present oxidation-resistive CuNi nanomesh electrodes that exhibit a low sheet resistance of ∼7.5 Ω/□ and a high optical transmittance of ∼81% at 550 nm. Further, high long-term stability against the effects of oxidation, heat, and chemicals is exhibited by the CuNi nanomesh, in comparison with the behavior of a pure Cu nanomesh sample.

  15. Effect of mechanical loads on stability of nanodomains in ferroelectric ultrathin films: towards flexible erasing of the non-volatile memories.

    Science.gov (United States)

    Chen, W J; Zheng, Yue; Xiong, W M; Feng, Xue; Wang, Biao; Wang, Ying

    2014-06-18

    Intensive investigations have been drawn on nanoscale ferroelectrics for their prospective applications such as developing memory devices. In contrast with the commonly used electrical means to process (i.e., read, write or erase) the information carried by ferroelectric domains, at present, mechanisms of non-electrical processing ferroelectric domains are relatively lacking. Here we make a systematical investigation on the stability of 180° cylindrical domains in ferroelectric nanofilms subjected to macroscopic mechanical loads, and explore the possibility of mechanical erasing. Effects of domain size, film thickness, temperature and different mechanical loads, including uniform strain, cylindrical bending and wavy bending, have been revealed. It is found that the stability of a cylindrical domain depends on its radius, temperature and film thickness. More importantly, mechanical loads have great controllability on the stability of cylindrical domains, with the critical radius nonlinearly sensitive to both strain and strain gradient. This indicates that erasing cylindrical domain can be achieved by changing the strain state of nanofilm. Based on the calculated phase diagrams, we successfully simulate several mechanical erasing processes on 4 × 4 bits memory devices. Our study sheds light on prospective device applications of ferroelectrics involving mechanical loads, such as flexible memory devices and other micro-electromechanical systems.

  16. A Novel Implementation of a Flexible Robotic Fin Actuated by Shape Memory Alloy

    Institute of Scientific and Technical Information of China (English)

    Qin Yan; Lei Wang; Bo Liu; Jie Yang; Shiwu Zhang

    2012-01-01

    In this paper,study of a novel flexible robotic-fin actuated by Shape Memory Alloy (SMA) is presented.The developed robotic fin is capable of implementing various 3-Dimensional (3D) motions,which plays an important role in robot propulsion and maneuverability.Firstly,the morphological and mechanics parameters of a real pectoral fin from a carp are investigated.Secondly,a detailed design of the flexible pectoral fin driven by SMA is presented according to the previous morphological and mechanics analyses.Thirdly,a simplified theoretical model on the SMA fin plate is derived.The thermodynamics of the SMA plate and the relationship between curvature and phase transformation are analyzed.Finally,several simulations and model experiments are conducted according to the previous analyses.The results of the experiments are useful for the control of the robotic fin.The experimental results reveal that the SMA actuated fin ray has a good actuating performance.

  17. Vibration Control of a Flexible Rotor Using Shape Memory Alloy Wires

    DEFF Research Database (Denmark)

    Alves, Marco Túlio Santana; Enemark, Søren; Steffen Jr, Valdar

    2015-01-01

    In the present contribution, a theoretical model of a test rig containing a flexible rotor is simulated considering pseudoelastic SMA (Shape Memory Alloy) wires connected to a bearing in order to dissipate energy and consequently reduce vibration. SMAs have characteristics of shape memory...... of rotor and SMA wires are coupled. The chosen constitutive model that governs the SMA behaviour is a modified version of the model by Brinson for the one-dimensional case. Both transient and steady-state tests arenumerically simulated. The first one, a run-up test, is performed only at room temperature....... In the second, the unbalancedrotor runs at the first critical speed and two cases are considered: i) room temperature; ii) time-varying temperature.The results from these evaluations show that SMA can be an interesting alternative for vibration control in rotating machinery....

  18. Chemically Integrated Inorganic-Graphene Two-Dimensional Hybrid Materials for Flexible Energy Storage Devices.

    Science.gov (United States)

    Peng, Lele; Zhu, Yue; Li, Hongsen; Yu, Guihua

    2016-12-01

    State-of-the-art energy storage devices are capable of delivering reasonably high energy density (lithium ion batteries) or high power density (supercapacitors). There is an increasing need for these power sources with not only superior electrochemical performance, but also exceptional flexibility. Graphene has come on to the scene and advancements are being made in integration of various electrochemically active compounds onto graphene or its derivatives so as to utilize their flexibility. Many innovative synthesis techniques have led to novel graphene-based hybrid two-dimensional nanostructures. Here, the chemically integrated inorganic-graphene hybrid two-dimensional materials and their applications for energy storage devices are examined. First, the synthesis and characterization of different kinds of inorganic-graphene hybrid nanostructures are summarized, and then the most relevant applications of inorganic-graphene hybrid materials in flexible energy storage devices are reviewed. The general design rules of using graphene-based hybrid 2D materials for energy storage devices and their current limitations and future potential to advance energy storage technologies are also discussed.

  19. SHADE: A Shape-Memory-Activated Device Promoting Ankle Dorsiflexion

    Science.gov (United States)

    Pittaccio, S.; Viscuso, S.; Rossini, M.; Magoni, L.; Pirovano, S.; Villa, E.; Besseghini, S.; Molteni, F.

    2009-08-01

    Acute post-stroke rehabilitation protocols include passive mobilization as a means to prevent contractures. A device (SHADE) that provides repetitive passive motion to a flaccid ankle by using shape memory alloy actuators could be of great help in providing this treatment. A suitable actuator was designed as a cartridge of approximately 150 × 20 × 15 mm, containing 2.5 m of 0.25 mm diameter NiTi wire. This actuator was activated by Joule’s effect employing a 7 s current input at 0.7 A, which provided 10 N through 76 mm displacement. Cooling and reset by natural convection took 30 s. A prototype of SHADE was assembled with two thermoplastic shells hinged together at the ankle and strapped on the shin and foot. Two actuators were fixed on the upper shell while an inextensible thread connected each NiTi wire to the foot shell. The passive ankle motion (passive range of motion, PROM) generated by SHADE was evaluated optoelectronically on three flaccid patients (58 ± 5 years old); acceptability was assessed by a questionnaire presented to further three flaccid patients (44 ± 11.5 years old) who used SHADE for 5 days, 30 min a day. SHADE was well accepted by all patients, produced good PROM, and caused no pain. The results prove that suitable limb mobilization can be produced by SMA actuators.

  20. A motionless actuation system for magnetic shape memory devices

    Science.gov (United States)

    Armstrong, Andrew; Finn, Kevin; Hobza, Anthony; Lindquist, Paul; Rafla, Nader; Müllner, Peter

    2017-10-01

    Ni–Mn–Ga is a Magnetic Shape Memory (MSM) alloy that changes shape in response to a variable magnetic field. We can intentionally manipulate the shape of the material to function as an actuator, and the material can thus replace complicated small electromechanical systems. In previous work, a very simple and precise solid-state micropump was developed, but a mechanical rotation was required to translate the position of the magnetic field. This mechanical rotation defeats the purpose of the motionless solid-state device. Here we present a solid-state electromagnetic driver to linearly progress the position of the applied magnetic field and the associated shrinkage. The generated magnetic field was focused at either of two pole pieces, providing a mechanism for moving the localized shrinkage in the MSM element. We confirmed that our driver has sufficient strength to actuate the MSM element using optical microscopy. We validated the whole design by comparing results obtained with finite element analysis with the experimentally measured flux density. This drive system serves as a possible replacement to the mechanical rotation of the magnetic field by using a multi-pole electromagnet that sweeps the magnetic field across the MSM micropump element, solid-state switching the current to each pole piece in the multi-pole electromagnet.

  1. Quantitative scanning thermal microscopy of graphene devices on flexible polyimide substrates

    Science.gov (United States)

    Sadeghi, Mir Mohammad; Park, Saungeun; Huang, Yu; Akinwande, Deji; Yao, Zhen; Murthy, Jayathi; Shi, Li

    2016-06-01

    A triple-scan scanning thermal microscopy (SThM) method and a zero-heat flux laser-heated SThM technique are investigated for quantitative thermal imaging of flexible graphene devices. A similar local tip-sample thermal resistance is observed on both the graphene and metal areas of the sample, and is attributed to the presence of a polymer residue layer on the sample surface and a liquid meniscus at the tip-sample junction. In addition, it is found that the tip-sample thermal resistance is insensitive to the temperature until it begins to increase as the temperature increases to 80 °C and exhibits an abrupt increase at 110 °C because of evaporation of the liquid meniscus at the tip-sample junction. Moreover, the variation in the tip-sample thermal resistance due to surface roughness is within the experimental tolerance except at areas with roughness height exceeding tens of nanometers. Because of the low thermal conductivity of the flexible polyimide substrate, the SThM measurements have found that the temperature rise in flexible graphene devices is more than one order of magnitude higher than those reported for graphene devices fabricated on a silicon substrate with comparable dimensions and power density. Unlike a graphene device on a silicon substrate where the majority of the electrical heating in the graphene device is conducted vertically through the thin silicon dioxide dielectric layer to the high-thermal conductivity silicon substrate, lateral heat spreading is important in the flexible graphene devices, as shown by the observed decrease in the average temperature rise normalized by the power density with decreasing graphene channel length from about 30 μm to 10 μm. However, it is shown by numerical heat transfer analysis that this trend is mainly caused by the size scaling of the thermal spreading resistance of the polymer substrate instead of lateral heat spreading by the graphene. In addition, thermoelectric effects are found to be negligible

  2. Metal-Phenolic Carbon Nanocomposites for Robust and Flexible Energy-Storage Devices.

    Science.gov (United States)

    Oh, Jun Young; Jung, Yeonsu; Cho, Young Shik; Choi, Jaeyoo; Youk, Ji Ho; Fechler, Nina; Yang, Seung Jae; Park, Chong Rae

    2017-01-05

    Future electronics applications such as wearable electronics depend on the successful construction of energy-storage devices with superior flexibility and high electrochemical performance. However, these prerequisites are challenging to combine: External forces often cause performance degradation, whereas the trade-off between the required nanostructures for strength and electrochemical performance only results in diminished energy storage. Herein, a flexible supercapacitor based on tannic acid (TA) and carbon nanotubes (CNTs) with a unique nanostructure is presented. TA was self-assembled on the surface of the CNTs by metal-phenolic coordination bonds, which provides the hybrid film with both high strength and high pseudocapacitance. Besides 17-fold increased mechanical strength of the final composite, the hybrid film simultaneously exhibits excellent flexibility and volumetric capacitance.

  3. Thermally switchable flexible liquid crystal devices in prepolymer-doped cholesteric liquid crystals

    Science.gov (United States)

    Fuh, A. Y.-G.; Li, J.-H.; Cheng, K.-T.

    2010-10-01

    This work describes an approach for fabricating thermally switchable flexible liquid crystal devices in prepolymer-doped cholesteric liquid crystals (CLCs). The roughness of the UV-cured polymer film eliminates the stability of planar CLCs, allowing the textures in the UV-cured regions to be changed from planar to focal conic. Impurities associated with doping with prepolymers cause the clearing temperature of LCs in the UV-cured regions to differ from that in the uncured regions as the prepolymers are polymerized. Therefore, the textures in these two regions can be switched by controlling the temperature. Thermally switchable flexible LC devices, such as optically addressed smart cards, light valves, and others, can be realized using this approach.

  4. Flexible viologen electrochromic devices with low operational voltages using reduced graphene oxide electrodes.

    Science.gov (United States)

    Palenzuela, Jesús; Viñuales, Ana; Odriozola, Ibon; Cabañero, Germán; Grande, Hans J; Ruiz, Virginia

    2014-08-27

    Reduced graphene oxide (RGO) films have been electrodeposited on indium tin oxide-coated polyethylene terephthalate (ITO-PET) substrates from graphene oxide (GO) solutions, and the resulting flexible transparent electrodes have been used in electrochromic devices of ethyl viologen (EtV(2+)). The electrochromic performance of devices with bare ITO-PET electrodes and ITO-PET coated with RGO has been compared. Under continuous cycling tests up to large voltages, the RGO film was oxidized and dispersed in the electrochromic mixture. The resulting devices, which contained GO and RGO in the electrochromic mixture, showed lower switching voltages between the colored and bleached states. This electrocatalytic activity of the solution-phase GO/RGO pair toward the electrochemical reaction of the electrochromic redox couple (the dication EtV(2+) and the radical cation EtV(+•)) allowed devices with an optical contrast higher than the contrast of those free of GO at the same applied voltage.

  5. A flexible and robust soft-error testing system for microelectronic devices and integrated circuits

    Institute of Scientific and Technical Information of China (English)

    王晓辉; 杨振雷; 童腾; 苏弘; 刘杰; 张战刚; 古松; 刘天奇; 孔洁; 赵兴文

    2015-01-01

    Single event effects (SEEs) induced by radiations become a significant reliability challenge for modern elec-tronic systems. To evaluate SEEs susceptibility for microelectronic devices and integrated circuits (ICs), an SEE testing system with flexibility and robustness was developed at Heavy Ion Research Facility in Lanzhou (HIRFL). The system is compatible with various types of microelectronic devices and ICs, and supports plenty of complex and high-speed test schemes and plans for the irradiated devices under test (DUTs). Thanks to the combination of meticulous circuit design and the hardened logic design, the system has additional performances to avoid an overheated situation and irradiations by stray radiations. The system has been tested and verified by experiments for irradiating devices at HIRFL.

  6. A Flexible and Thin Graphene/Silver Nanowires/Polymer Hybrid Transparent Electrode for Optoelectronic Devices.

    Science.gov (United States)

    Dong, Hua; Wu, Zhaoxin; Jiang, Yaqiu; Liu, Weihua; Li, Xin; Jiao, Bo; Abbas, Waseem; Hou, Xun

    2016-11-16

    A typical thin and fully flexible hybrid electrode was developed by integrating the encapsulation of silver nanowires (AgNWs) network between a monolayer graphene and polymer film as a sandwich structure. Compared with the reported flexible electrodes based on PET or PEN substrate, this unique electrode exhibits the superior optoelectronic characteristics (sheet resistance of 8.06 Ω/□ at 88.3% light transmittance). Meanwhile, the specific up-to-bottom fabrication process could achieve the superflat surface (RMS = 2.58 nm), superthin thickness (∼8 μm thickness), high mechanical robustness, and lightweight. In addition, the strong corrosion resistance and stability for the hybrid electrode were proved. With these advantages, we employ this electrode to fabricate the simple flexible organic light-emitting device (OLED) and perovskite solar cell device (PSC), which exhibit the considerable performance (best PCE of OLED = 2.11 cd/A(2); best PCE of PSC = 10.419%). All the characteristics of the unique hybrid electrode demonstrate its potential as a high-performance transparent electrode candidate for flexible optoelectronics.

  7. A Study on Electrical Performances and Lifetime of a Flexible Electrochromic Textile Device

    Directory of Open Access Journals (Sweden)

    Moretti Constance

    2014-06-01

    Full Text Available Using their ability to change their color according to an external stimulation, chromic materials can be used to form a color-changing textile. Electrochromism, more particularly, is a colour change phenomenon caused by the application of an electrical potential. A flexible textile electrochromic device composed of four layers is presented. In order to improve the lifetime of this structure, the electrical performances of the electrolyte layer are studied. A method to measure and calculate the resistance variations of the electrolyte applied on a textile cotton substrate is given. Relations between the electrical performances of the electrolyte and the electrochromic effect of the device are also highlighted.

  8. A review of the scalable nano-manufacturing technology for flexible devices

    Science.gov (United States)

    Huang, Wenbin; Yu, Xingtao; Liu, Yanhua; Qiao, Wen; Chen, Linsen

    2017-01-01

    Recent advances in electronic and photonic devices, such as artificial skin, wearable systems, organic and inorganic light-emitting diodes, have gained considerable commercial and scientific interest in the academe and in industries. However, low-cost and high-throughput nano-manufacturing is difficult to realize with the use of traditional photolithographic processes. In this review, we summarize the status and the limitations of current nanopatterning techniques for scalable and flexible functional devices in terms of working principle, resolution, and processing speed. Finally, several remaining unsolved problems in nano-manufacturing are discussed, and future research directions are highlighted.

  9. A review of the scalable nano-manufacturing technology for flexible devices

    Science.gov (United States)

    Huang, Wenbin; Yu, Xingtao; Liu, Yanhua; Qiao, Wen; Chen, Linsen

    2017-03-01

    Recent advances in electronic and photonic devices, such as artificial skin, wearable systems, organic and inorganic light-emitting diodes, have gained considerable commercial and scientific interest in the academe and in industries. However, low-cost and high-throughput nano-manufacturing is difficult to realize with the use of traditional photolithographic processes. In this review, we summarize the status and the limitations of current nanopatterning techniques for scalable and flexible functional devices in terms of working principle, resolution, and processing speed. Finally, several remaining unsolved problems in nano-manufacturing are discussed, and future research directions are highlighted.

  10. A flexible super-capacitive solid-state power supply for miniature implantable medical devices.

    Science.gov (United States)

    Meng, Chuizhou; Gall, Oren Z; Irazoqui, Pedro P

    2013-12-01

    We present a high-energy local power supply based on a flexible and solid-state supercapacitor for miniature wireless implantable medical devices. Wireless radio-frequency (RF) powering recharges the supercapacitor through an antenna with an RF rectifier. A power management circuit for the super-capacitive system includes a boost converter to increase the breakdown voltage required for powering device circuits, and a parallel conventional capacitor as an intermediate power source to deliver current spikes during high current transients (e.g., wireless data transmission). The supercapacitor has an extremely high area capacitance of ~1.3 mF/mm(2), and is in the novel form of a 100 μm-thick thin film with the merit of mechanical flexibility and a tailorable size down to 1 mm(2) to meet various clinical dimension requirements. We experimentally demonstrate that after fully recharging the capacitor with an external RF powering source, the supercapacitor-based local power supply runs a full system for electromyogram (EMG) recording that consumes ~670 μW with wireless-data-transmission functionality for a period of ~1 s in the absence of additional RF powering. Since the quality of wireless powering for implantable devices is sensitive to the position of those devices within the RF electromagnetic field, this high-energy local power supply plays a crucial role in providing continuous and reliable power for medical device operations.

  11. NASA Flexible Screen Propellant Management Device (PMD) Demonstration With Cryogenic Liquid

    Science.gov (United States)

    Wollen, Mark; Bakke, Victor; Baker, James

    2012-01-01

    While evaluating various options for liquid methane and liquid oxygen propellant management for lunar missions, Innovative Engineering Solutions (IES) conceived the flexible screen device as a potential simple alternative to conventional propellant management devices (PMD). An apparatus was designed and fabricated to test flexible screen devices in liquid nitrogen. After resolution of a number of issues (discussed in detail in the paper), a fine mesh screen (325 by 2300 wires per inch) spring return assembly was successfully tested. No significant degradation in the screen bubble point was observed either due to the screen stretching process or due to cyclic fatigue during testing. An estimated 30 to 50 deflection cycles, and approximately 3 to 5 thermal cycles, were performed on the final screen specimen, prior to and between formally recorded testing. These cycles included some "abusive" pressure cycling, where gas or liquid was driven through the screen at rates that produced differential pressures across the screen of several times the bubble point pressure. No obvious performance degradation or other changes were observed over the duration of testing. In summary, it is felt by the author that these simple tests validated the feasibility of the flexible screen PMD concept for use with cryogenic propellants.

  12. Metal-organic molecular device for non-volatile memory storage

    Energy Technology Data Exchange (ETDEWEB)

    Radha, B., E-mail: radha.boya@manchester.ac.uk, E-mail: kulkarni@jncasr.ac.in; Sagade, Abhay A.; Kulkarni, G. U., E-mail: radha.boya@manchester.ac.uk, E-mail: kulkarni@jncasr.ac.in [Chemistry and Physics of Materials Unit and DST Unit on Nanoscience, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064 (India)

    2014-08-25

    Non-volatile memory devices have been of immense research interest for their use in active memory storage in powered off-state of electronic chips. In literature, various molecules and metal compounds have been investigated in this regard. Molecular memory devices are particularly attractive as they offer the ease of storing multiple memory states in a unique way and also represent ubiquitous choice for miniaturized devices. However, molecules are fragile and thus the device breakdown at nominal voltages during repeated cycles hinders their practical applicability. Here, in this report, a synergetic combination of an organic molecule and an inorganic metal, i.e., a metal-organic complex, namely, palladium hexadecylthiolate is investigated for memory device characteristics. Palladium hexadecylthiolate following partial thermolysis is converted to a molecular nanocomposite of Pd(II), Pd(0), and long chain hydrocarbons, which is shown to exhibit non-volatile memory characteristics with exceptional stability and retention. The devices are all solution-processed and the memory action stems from filament formation across the pre-formed cracks in the nanocomposite film.

  13. A Sandwiched/Cracked Flexible Film for Multi-Thermal Monitoring and Switching Devices

    KAUST Repository

    Tai, Yanlong

    2017-08-30

    Polydimethylsiloxane (PDMS)-based flexible films have substantiated advantages in various sensing applications. Here, we demonstrate the highly sensitive and programmable thermal-sensing capability (thermal index, B, up to 126 × 103 K) of flexible films with tunable sandwiched microstructures (PDMS/cracked single-walled carbon nanotube (SWCNT) film/PDMS) when a thermal stimulus is applied. We found that this excellent performance results from the following features of the film\\'s structural and material design: (1) the sandwiched structure allows the film to switch from a three-dimensional to a two-dimensional in-plane deformation and (2) the stiffness of the SWCNT film is decreased by introducing microcracks that make deformation easy and that promote the macroscopic piezoresistive behavior of SWCNT crack islands and the microscopic piezoresistive behavior of SWCNT bundles. The PDMS layer is characterized by a high coefficient of thermal expansion (α = 310 × 10-6 K-1) and low stiffness (∼2 MPa) that allow for greater flexibility and higher temperature sensitivity. We determined the efficacy of our sandwiched, cracked, flexible films in monitoring and switching flexible devices when subjected to various stimuli, including thermal conduction, thermal radiation, and light radiation.

  14. Fabrication and electrical characterization of a MOS memory device containing self-assembled metallic nanoparticles

    Science.gov (United States)

    Sargentis, Ch.; Giannakopoulos, K.; Travlos, A.; Tsamakis, D.

    2007-04-01

    Floating gate devices with nanoparticles embedded in dielectrics have recently attracted much attention due to the fact that these devices operate as non-volatile memories with high speed, high density and low power consumption. In this paper, memory devices containing gold (Au) nanoparticles have been fabricated using e-gun evaporation. The Au nanoparticles are deposited on a very thin SiO 2 layer and are then fully covered by a HfO 2 layer. The HfO 2 is a high- k dielectric and gives good scalability to the fabricated devices. We studied the effect of the deposition parameters to the size and the shape of the Au nanoparticles using capacitance-voltage and conductance-voltage measurements, we demonstrated that the fabricated device can indeed operate as a low-voltage memory device.

  15. Configurable memory system and method for providing atomic counting operations in a memory device

    Science.gov (United States)

    Bellofatto, Ralph E.; Gara, Alan G.; Giampapa, Mark E.; Ohmacht, Martin

    2010-09-14

    A memory system and method for providing atomic memory-based counter operations to operating systems and applications that make most efficient use of counter-backing memory and virtual and physical address space, while simplifying operating system memory management, and enabling the counter-backing memory to be used for purposes other than counter-backing storage when desired. The encoding and address decoding enabled by the invention provides all this functionality through a combination of software and hardware.

  16. Ferroelectric-gate field effect transistor memories device physics and applications

    CERN Document Server

    Ishiwara, Hiroshi; Okuyama, Masanori; Sakai, Shigeki; Yoon, Sung-Min

    2016-01-01

    This book provides comprehensive coverage of the materials characteristics, process technologies, and device operations for memory field-effect transistors employing inorganic or organic ferroelectric thin films. This transistor-type ferroelectric memory has interesting fundamental device physics and potentially large industrial impact. Among the various applications of ferroelectric thin films, the development of nonvolatile ferroelectric random access memory (FeRAM) has progressed most actively since the late 1980s and has achieved modest mass production levels for specific applications since 1995. There are two types of memory cells in ferroelectric nonvolatile memories. One is the capacitor-type FeRAM and the other is the field-effect transistor (FET)-type FeRAM. Although the FET-type FeRAM claims ultimate scalability and nondestructive readout characteristics, the capacitor-type FeRAMs have been the main interest for the major semiconductor memory companies, because the ferroelectric FET has fatal handic...

  17. Modeling of a flexible beam actuated by shape memory alloy wires

    Science.gov (United States)

    Shu, Steven G.; Lagoudas, Dimitris C.; Hughes, Declan; Wen, John T.

    1997-06-01

    A thermomechanical model is developed to predict the structural response of a flexible beam with shape memory alloy (SMA) wire actuators. A geometrically nonlinear static analysis is first carried out to investigate the deformed shape of a flexible cantilever beam caused by an externally-attached SMA wire actuated electrically. The actuation force applied by the SMA actuator to the beam is evaluated by solving a coupled problem that combines a thermodynamic constitutive model of SMAs with the heat conduction equation in the SMA and the structural model of the beam. To calculate the temperature history of the SMA actuator for given electrical current input, the heat transfer equation is solved with the electrical resistive heating being modeled as a distributed heat source along the SMA wire. The steps in the formulation are connected together through an iterative scheme that takes into account the static equilibrium of the beam and the constitutive relation of SMAs, thus translating an electrical current history input into beam strain output. The proposed model is used to simulate the experimental results, thus demonstrating the feasibility of using SMA actuators for shape control of active flexible structural systems.

  18. Flexible and stretchable electronics for wearable healthcare devices and minimally invasive surgical tools

    Science.gov (United States)

    Kim, Dae-Hyeong; Lee, Mincheol; Lee, Hyunjae

    2016-05-01

    Recent advances in soft electronics have attracted great attention, largely due to their potential applications in personalized, bio-integrated healthcare devices. The mechanical mismatch between conventional electronic/optoelectronic devices and soft human tissues/organs have presented many challenges, such as the low signalto- noise ratio of biosensors because of the incomplete integration of rigid devices with the body, inflammation and excessive immune responses of implanted stiff devices originated from friction and their foreign nature to biotic systems, and the considerable discomfort and consequent stress experienced by users when wearing/implanting these devices. Ultra-flexible and stretchable electronic devices are being highlighted due to their low system modulus and the intrinsic system-level softness that are important to solve these issues. Here, we describe our unique strategies for the nanomaterial synthesis and fabrication, their seamless assembly and integration, and the design and development of corresponding wearable healthcare devices and minimally invasive surgical tools. These bioelectronic systems fully utilize recent breakthroughs in unconventional soft electronics based on nanomaterials to address unsolved issues in clinical medicine and to provide new opportunities in the personalized healthcare.

  19. Nonvolatile write-once-read-many-times memory device with functionalized-nanoshells/PEDOT:PSS nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Avila-Nino, J.A.; Segura-Cardenas, E. [Universidad Autonoma de San Luis Potosi, Instituto de Investigacion en Comunicacion Optica, Alvaro Obregon 64 Zona Centro, 78000 SLP (Mexico); Sustaita, A.O. [Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la presa San Jose 2055, CP 78216, San Luis Potosi (Mexico); Cruz-Cruz, I. [Universidad Autonoma de San Luis Potosi, Instituto de Investigacion en Comunicacion Optica, Alvaro Obregon 64 Zona Centro, 78000 SLP (Mexico); Lopez-Sandoval, R. [Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la presa San Jose 2055, CP 78216, San Luis Potosi (Mexico); Reyes-Reyes, M., E-mail: reyesm@iico.uaslp.mx [Universidad Autonoma de San Luis Potosi, Instituto de Investigacion en Comunicacion Optica, Alvaro Obregon 64 Zona Centro, 78000 SLP (Mexico)

    2011-03-25

    We have investigated the memory effect of the nanocomposites of functionalized carbon nanoshells (f-CNSs) mixed with poly(3,4-ethylenedioxythiophene) doped with polystyrenesulfonate (PEDOT:PSS) polymer. The f-CNSs were synthesized by the spray pyrolysis method and functionalized in situ with functional groups (OH, COOH, C-H, C-OH) with the aim of improving their compatibility in the aqueous dispersion of PEDOT:PSS. The current-voltage (I-V) sweep curves at room temperature for the Al/f-CNSs, for certain concentrations range, embedded in a PEDOT:PSS layer/Al devices showed electrical bistability for write-once-read-many-times (WORM) memory devices. The memory effect observed in the devices can be explained due to the existence of trapped charges in the f-CNSs/PEDOT:PSS layer. The carrier transport mechanisms for the memory devices is studied and discussed.

  20. Fixation of external drainage device with injectable shape-memory alloy clips.

    Science.gov (United States)

    Olson, Jeffrey L; Erlanger, Michael

    2013-09-01

    To describe a novel surgical technique and novel surgical instrumentation for fixating an extraocular drainage device used for glaucoma-filtering surgery. The technique was performed in a laboratory setting using ex-vivo porcine eyes. We describe the surgical technique of using injectable, 25-gauge shape-memory clip system to fixate an Ahmed drainage device. The use of an injectable, shape-memory alloy clip provides the advantages of rapid, easy deployment and decreased risk of late suture failure. Importantly, the injectable, shape-memory clips can be used in surgical situations where suturing is difficult and time intensive, such as those encountered during glaucoma drainage device placement. The use of an injectable, shape-memory alloy clip is a promising new surgical tool and technique for fixating an extraocular drainage device used for glaucoma surgery.

  1. Nanoalloy Printed and Pulse-Laser Sintered Flexible Sensor Devices with Enhanced Stability and Materials Compatibility

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Wei; Rovore, Thomas; Weerawarne, Darshana; Osterhoudt, Gavin; Kang, Ning; Joseph, Pharrah; Luo, Jin; Shim, Bonggu; Poliks, Mark; Zhong, Chuan-Jian

    2015-06-02

    While conformal and wearable devices have become one of the most desired formats for printable electronics, it is challenging to establish a scalable process that produces stable conductive patterns but also uses substrates compatible with widely available wearable materials. Here, we describe findings of an investigation of a nanoalloy ink printed and pulsed laser sintered conductive patterns as flexible functional devices with enhanced stability and materials compatibility. While nanoparticle inks are desired for printable electronics, almost all existing nanoparticle inks are based on single-metal component, which, as an electronic element, is limited by its inherent stabilities of the metal such as propensity of metal oxidation and mobility of metal ions, especially in sintering processes. The work here has demonstrated the first example in exploiting plasmonic coupling of nanoalloys and pulsed-laser energy with controllable thermal penetration. The experimental and theoretical results have revealed clear correlation between the pulsed laser parameters and the nanoalloy structural characteristics. The superior performance of the resulting flexible sensor device, upon imparting nanostructured sensing materials, for detecting volatile organic compounds has significant implications to developing stable and wearable sensors for monitoring environmental pollutants and breath biomarkers. This simple “nanoalloy printing 'laser sintering' nanostructure printing” process is entirely general to many different sensor devices and nanostructured sensing materials, enabling the ability to easily construct sophisticated sensor array.

  2. Flexible microfluidic device for mechanical property characterization of soft viscoelastic solids such as bacterial biofilms.

    Science.gov (United States)

    Hohne, Danial N; Younger, John G; Solomon, Michael J

    2009-07-01

    We introduce a flexible microfluidic device to characterize the mechanical properties of soft viscoelastic solids such as bacterial biofilms. In the device, stress is imposed on a test specimen by the application of a fixed pressure to a thin, flexible poly(dimethyl siloxane) (PDMS) membrane that is in contact with the specimen. The stress is applied by pressurizing a microfabricated air channel located above the test area. The strain resulting from the applied stress is quantified by measuring the membrane deflection with a confocal laser scanning microscope. The deflection is governed by the viscoelastic properties of the PDMS membrane and of the test specimen. The relative contributions of the membrane and test material to the measured deformation are quantified by comparing a finite element analysis with an independent (control) measurement of the PDMS membrane mechanical properties. The flexible microfluidic rheometer was used to characterize both the steady-state elastic modulus and the transient strain recoil of two soft materials: gellan gums and bacterial biofilms. The measured linear elastic moduli and viscoelastic relaxation times of gellan gum solutions were in good agreement with the results of conventional mechanical rheometry. The linear Young's moduli of biofilms of Staphylococcus epidermidis and Klebsiella pneumoniae, which could not be measured using conventional methods, were found to be 3.2 and 1.1 kPa, respectively, and the relaxation time of the S. epidermidis biofilm was 13.8 s. Additionally, strain hardening was observed in all the biofilms studied. Finally, design parameters and detection limits of the method show that the device is capable of characterizing soft viscoelastic solids with elastic moduli in the range of 102-105 Pa. The flexible microfluidic rheometer addresses the need for mechanical property characterization of soft viscoelastic solids common in fields such as biomaterials, food, and consumer products. It requires only 200 p

  3. Observation of long term potentiation in papain-based memory devices

    KAUST Repository

    Bag, A.

    2014-06-01

    Biological synaptic behavior in terms of long term potentiation has been observed in papain-based (plant protein) memory devices (memristors) for the first time. Improvement in long term potentiation depends on pulse amplitude and width (duration). Continuous/repetitive dc voltage sweep leads to an increase in memristor conductivity leading to a long term memory in the \\'learning\\' processes.

  4. Multiterminal Memristive Nanowire Devices for Logic and Memory Applications: A Review

    OpenAIRE

    Sacchetto, Davide; De Micheli, Giovanni; Leblebici, Yusuf

    2012-01-01

    Memristive devices have the potential for a complete renewal of the electron devices landscape, including memory, logic, and sensing applications. This is especially true when considering that the memristive functionality is not limited to two-terminal devices, whose practical realization has been demonstrated within a broad range of different technologies. For electron devices, the memristive functionality can be generally attributed to a material state modification, whose dynamics can be en...

  5. A neural framework for organization and flexible utilization of episodic memory in cumulatively learning baby humanoids.

    Science.gov (United States)

    Mohan, Vishwanathan; Sandini, Giulio; Morasso, Pietro

    2014-12-01

    Cumulatively developing robots offer a unique opportunity to reenact the constant interplay between neural mechanisms related to learning, memory, prospection, and abstraction from the perspective of an integrated system that acts, learns, remembers, reasons, and makes mistakes. Situated within such interplay lie some of the computationally elusive and fundamental aspects of cognitive behavior: the ability to recall and flexibly exploit diverse experiences of one's past in the context of the present to realize goals, simulate the future, and keep learning further. This article is an adventurous exploration in this direction using a simple engaging scenario of how the humanoid iCub learns to construct the tallest possible stack given an arbitrary set of objects to play with. The learning takes place cumulatively, with the robot interacting with different objects (some previously experienced, some novel) in an open-ended fashion. Since the solution itself depends on what objects are available in the "now," multiple episodes of past experiences have to be remembered and creatively integrated in the context of the present to be successful. Starting from zero, where the robot knows nothing, we explore the computational basis of organization episodic memory in a cumulatively learning humanoid and address (1) how relevant past experiences can be reconstructed based on the present context, (2) how multiple stored episodic memories compete to survive in the neural space and not be forgotten, (3) how remembered past experiences can be combined with explorative actions to learn something new, and (4) how multiple remembered experiences can be recombined to generate novel behaviors (without exploration). Through the resulting behaviors of the robot as it builds, breaks, learns, and remembers, we emphasize that mechanisms of episodic memory are fundamental design features necessary to enable the survival of autonomous robots in a real world where neither everything can be known

  6. Non-volatile memory devices with redox-active diruthenium molecular compound

    Science.gov (United States)

    Pookpanratana, S.; Zhu, H.; Bittle, E. G.; Natoli, S. N.; Ren, T.; Richter, C. A.; Li, Q.; Hacker, C. A.

    2016-03-01

    Reduction-oxidation (redox) active molecules hold potential for memory devices due to their many unique properties. We report the use of a novel diruthenium-based redox molecule incorporated into a non-volatile Flash-based memory device architecture. The memory capacitor device structure consists of a Pd/Al2O3/molecule/SiO2/Si structure. The bulky ruthenium redox molecule is attached to the surface by using a ‘click’ reaction and the monolayer structure is characterized by x-ray photoelectron spectroscopy to verify the Ru attachment and molecular density. The ‘click’ reaction is particularly advantageous for memory applications because of (1) ease of chemical design and synthesis, and (2) provides an additional spatial barrier between the oxide/silicon to the diruthenium molecule. Ultraviolet photoelectron spectroscopy data identified the energy of the electronic levels of the surface before and after surface modification. The molecular memory devices display an unsaturated charge storage window attributed to the intrinsic properties of the redox-active molecule. Our findings demonstrate the strengths and challenges with integrating molecular layers within solid-state devices, which will influence the future design of molecular memory devices.

  7. A Compact Kapton-based Inkjet Printed Multiband Antenna for Flexible Wireless Devices

    KAUST Repository

    Ahmed, Sana

    2015-04-20

    A low cost inkjet printed multiband antenna envisioned for integration into flexible and conformal mobile devices is presented. The antenna structure contains a novel triangular iterative design with coplanar waveguide (CPW) feed, printed on a Kapton polyimide-based flexible substrate with dimensions of 70 x 70 x 0.11 mm3. The antenna covers four wide frequency bands with measured impedance bandwidths of 54.4%, 14%, 23.5% and 17.2%, centered at 1.2, 2.0, 2.6 and 3.4 GHz, respectively, thus, enabling it to cover GSM 900, GPS, UMTS, WLAN, ISM, Bluetooth, LTE 2300/ 2500 and WiMAX standards. The antenna has omnidirectional radiation pattern with a maximum gain of 2.1 dBi. To characterize the flexibility of the antenna, the fabricated prototype is tested in convex and concave bent configurations for radii of 78mm and 59mm. The overall performance remains unaffected, except a minor shift of 20 MHz and 60 MHz in S11, for concave bending at both radii. The compact, lightweight and conformal design as well as multiband performance in bent configurations, proves the suitability of the antenna for future electronic devices.

  8. Performance Measurement of a Multi-Level/Analog Ferroelectric Memory Device Design

    Science.gov (United States)

    MacLeod, Todd C.; Phillips, Thomas A.; Ho, Fat D.

    2007-01-01

    Increasing the memory density and utilizing the unique characteristics of ferroelectric devices is important in making ferroelectric memory devices more desirable to the consumer. This paper describes the characterization of a design that allows multiple levels to be stored in a ferroelectric based memory cell. It can be used to store multiple bits or analog values in a high speed nonvolatile memory. The design utilizes the hysteresis characteristic of ferroelectric transistors to store an analog value in the memory cell. The design also compensates for the decay of the polarization of the ferroelectric material over time. This is done by utilizing a pair of ferroelectric transistors to store the data. One transistor is used a reference to determinethe amount of decay that has occurred since the pair was programmed. The second transistor stores the analog value as a polarization value between zero and saturated. The design allows digital data to be stored as multiple bits in each memory cell. The number of bits per cell that can be stored will vary with the decay rate of the ferroelectric transistors and the repeatability of polarization between transistors. This paper presents measurements of an actual prototype memory cell. This prototype is not a complete implementation of a device, but instead, a prototype of the storage and retrieval portion of an actual device. The performance of this prototype is presented with the projected performance of the overall device. This memory design will be useful because it allows higher memory density, compensates for the environmental and ferroelectric aging processes, allows analog values to be directly stored in memory, compensates for the thermal and radiation environments associated with space operations, and relies only on existing technologies.

  9. Design of a Molecular Memory Device: The Electron Transfer Shift Register Memory

    Science.gov (United States)

    Beratan, D.

    1993-01-01

    A molecular shift register memory at the molecular level is described. The memory elements consist of molecules can exit in either an oxidized or reduced state and the bits are shifted between the cells with photoinduced electron transfer reactions.

  10. Flexible daylight memory displays EASL DMD: a new approach toward displays for cockpit and soldier systems

    Science.gov (United States)

    Holter, Borre; Kamfjord, Thor G.; Fossum, Richard; Fagerberg, Ragnar

    2000-08-01

    The Norwegian based company PolyDisplayR ASA, in collaboration with the Norwegian Army Material Command and SINTEF, has refined, developed and shown with color and black/white technology demonstrators an electrically addressed Smectic A reflective LCD technology featuring: (1) Good contrast, all-round viewing angle and readability under all light conditions (no wash-out in direct sunlight). (2) Infinite memory -- image remains without power -- very low power consumption, no or very low radiation ('silent display') and narrow band updating. (3) Clear, sharp and flicker-free images. (4) Large number of gray tones and colors possible. (5) Simple construction and production -- reduced cost, higher yield, more robust and environmentally friendly. (6) Possibility for lighter, more robust and flexible displays based on plastic substrates. The results and future implementation possibilities for cockpit and soldier-system displays are discussed.

  11. Miniaturized vortex transitional Josephson memory cell by a vertically integrated device structure

    Energy Technology Data Exchange (ETDEWEB)

    Nagasawa, Shuichi; Tahara, Shuichi; Numata, Hideaki; Tsuchida, Sanae (NEC Corp., Tsukuba (Japan))

    1994-03-01

    We have developed the smallest Josephson nondestructive read-out (NDRO) memory cell, called a vortex transitional (VT) memory cell, for a Josephson high-speed 16-Kbit RAM. Its size is 22 x 22 microns(sup 2), which is only 16% of the size of previously developed VT memory cells used in Josephson 4-Kbit RAM. This is achieved by developing a vertically integrated device structure and refining small-junction technology. The cell consists of Nb/AlO(sub x)/Nb junctions, three Nb wirings, SiO2 insulators and Mo resistors. The VT memory cells operate properly, with a large operating margin of +/- 20%. 13 refs.

  12. Vibration confinement and energy harvesting in flexible structures using collocated absorbers and piezoelectric devices

    Science.gov (United States)

    Ouled Chtiba, M.; Choura, S.; Nayfeh, A. H.; El-Borgi, S.

    2010-03-01

    We propose an optimal design for supplementing flexible structures with a set of absorbers and piezoelectric devices for vibration confinement and energy harvesting. We assume that the original structure is sensitive to vibrations and that the absorbers are the elements where the vibration energy is confined and then harvested by means of piezoelectric devices. The design of the additional mechanical and electrical components is formulated as a dynamic optimization problem in which the objective function is the total energy of the uncontrolled structure. The locations, masses, stiffnesses, and damping coefficients of these absorbers and capacitances, load resistances, and electromechanical coupling coefficients are optimized to minimize the total energy of the structure. We use the Galerkin procedure to discretize the equations of motion that describe the coupled dynamics of the flexible structure and the added absorbers and harvesting devices. We develop a numerical code that determines the unknown parameters of a pre-specified set of absorbers and harvesting components. We input a set of initial values for these parameters, and the code updates them while minimizing the total energy in the uncontrolled structure. To illustrate the proposed design, we consider a simply supported beam with harmonic external excitations. Here, we consider two possible configurations for each of the additional piezoelectric devices, either embedded between the structure and the absorbers or between the ground and absorbers. We present simulations of the harvested power and associated voltage for each pair of collocated absorber and piezoelectric device. The simulated responses of the beam show that its energy is confined and harvested simultaneously.

  13. Memory operation devices based on light-illumination ambipolar carbon-nanotube thin-film-transistors

    Energy Technology Data Exchange (ETDEWEB)

    Aïssa, B., E-mail: aissab@emt.inrs.ca [Qatar Environment and Energy Research Institute (QEERI), Qatar Foundation, P.O. Box 5825, Doha (Qatar); Centre Energie, Matériaux et Télécommunications, INRS, 1650, Boulevard Lionel-Boulet Varennes, Quebec J3X 1S2 (Canada); Nedil, M. [Telebec Wireless Underground Communication Laboratory, UQAT, 675, 1ère Avenue, Val d' Or, Quebec J9P 1Y3 (Canada); Kroeger, J. [NanoIntegris & Raymor Nanotech, Raymor Industries Inc., 3765 La Vérendrye, Boisbriand, Quebec J7H 1R8 (Canada); Haddad, T. [Department of Mechanical Engineering, McGill University, Montreal, Quebec H3A 0B8 (Canada); Rosei, F. [Centre Energie, Matériaux et Télécommunications, INRS, 1650, Boulevard Lionel-Boulet Varennes, Quebec J3X 1S2 (Canada)

    2015-09-28

    We report the memory operation behavior of a light illumination ambipolar single-walled carbon nanotube thin film field-effect transistors devices. In addition to the high electronic-performance, such an on/off transistor-switching ratio of 10{sup 4} and an on-conductance of 18 μS, these memory devices have shown a high retention time of both hole and electron-trapping modes, reaching 2.8 × 10{sup 4} s at room temperature. The memory characteristics confirm that light illumination and electrical field can act as an independent programming/erasing operation method. This could be a fundamental step toward achieving high performance and stable operating nanoelectronic memory devices.

  14. Fabrication of graphene-based flexible devices utilizing a soft lithographic patterning method.

    Science.gov (United States)

    Jung, Min Wook; Myung, Sung; Kim, Ki Woong; Song, Wooseok; Jo, You-Young; Lee, Sun Suk; Lim, Jongsun; Park, Chong-Yun; An, Ki-Seok

    2014-07-18

    There has been considerable interest in soft lithographic patterning processing of large scale graphene sheets due to the low cost and simplicity of the patterning process along with the exceptional electrical or physical properties of graphene. These properties include an extremely high carrier mobility and excellent mechanical strength. Recently, a study has reported that single layer graphene grown via chemical vapor deposition (CVD) was patterned and transferred to a target surface by controlling the surface energy of the polydimethylsiloxane (PDMS) stamp. However, applications are limited because of the challenge of CVD-graphene functionalization for devices such as chemical or bio-sensors. In addition, graphene-based layers patterned with a micron scale width on the surface of biocompatible silk fibroin thin films, which are not suitable for conventional CMOS processes such as the patterning or etching of substrates, have yet to be reported. Herein, we developed a soft lithographic patterning process via surface energy modification for advanced graphene-based flexible devices such as transistors or chemical sensors. Using this approach, the surface of a relief-patterned elastomeric stamp was functionalized with hydrophilic dimethylsulfoxide molecules to enhance the surface energy of the stamp and to remove the graphene-based layer from the initial substrate and transfer it to a target surface. As a proof of concept using this soft lithographic patterning technique, we demonstrated a simple and efficient chemical sensor consisting of reduced graphene oxide and a metallic nanoparticle composite. A flexible graphene-based device on a biocompatible silk fibroin substrate, which is attachable to an arbitrary target surface, was also successfully fabricated. Briefly, a soft lithographic patterning process via surface energy modification was developed for advanced graphene-based flexible devices such as transistors or chemical sensors and attachable devices on a

  15. Mechanically flexible optically transparent silicon fabric with high thermal budget devices from bulk silicon (100)

    KAUST Repository

    Hussain, Muhammad Mustafa

    2013-05-30

    Today’s information age is driven by silicon based electronics. For nearly four decades semiconductor industry has perfected the fabrication process of continuingly scaled transistor – heart of modern day electronics. In future, silicon industry will be more pervasive, whose application will range from ultra-mobile computation to bio-integrated medical electronics. Emergence of flexible electronics opens up interesting opportunities to expand the horizon of electronics industry. However, silicon – industry’s darling material is rigid and brittle. Therefore, we report a generic batch fabrication process to convert nearly any silicon electronics into a flexible one without compromising its (i) performance; (ii) ultra-large-scale-integration complexity to integrate billions of transistors within small areas; (iii) state-of-the-art process compatibility, (iv) advanced materials used in modern semiconductor technology; (v) the most widely used and well-studied low-cost substrate mono-crystalline bulk silicon (100). In our process, we make trenches using anisotropic reactive ion etching (RIE) in the inactive areas (in between the devices) of a silicon substrate (after the devices have been fabricated following the regular CMOS process), followed by a dielectric based spacer formation to protect the sidewall of the trench and then performing an isotropic etch to create caves in silicon. When these caves meet with each other the top portion of the silicon with the devices is ready to be peeled off from the bottom silicon substrate. Release process does not need to use any external support. Released silicon fabric (25 μm thick) is mechanically flexible (5 mm bending radius) and the trenches make it semi-transparent (transparency of 7%). © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  16. Ferroelectric Thin Films Basic Properties and Device Physics for Memory Applications

    CERN Document Server

    Okuyama, Masanori

    2005-01-01

    Ferroelectric thin films continue to attract much attention due to their developing, diverse applications in memory devices, FeRAM, infrared sensors, piezoelectric sensors and actuators. This book, aimed at students, researchers and developers, gives detailed information about the basic properties of these materials and the associated device physics. All authors are acknowledged experts in the field.

  17. Scalable Heuristics for Planning, Placement and Sizing of Flexible AC Transmission System Devices

    Energy Technology Data Exchange (ETDEWEB)

    Frolov, Vladmir [Skolkovo Institute of Science and Technology, Skolkovo (Russia); Backhaus, Scott N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chertkov, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-07-02

    Aiming to relieve transmission grid congestion and improve or extend feasibility domain of the operations, we build optimization heuristics, generalizing standard AC Optimal Power Flow (OPF), for placement and sizing of Flexible Alternating Current Transmission System (FACTS) devices of the Series Compensation (SC) and Static VAR Compensation (SVC) type. One use of these devices is in resolving the case when the AC OPF solution does not exist because of congestion. Another application is developing a long-term investment strategy for placement and sizing of the SC and SVC devices to reduce operational cost and improve power system operation. SC and SVC devices are represented by modification of the transmission line inductances and reactive power nodal corrections respectively. We find one placement and sizing of FACTs devices for multiple scenarios and optimal settings for each scenario simultaneously. Our solution of the nonlinear and nonconvex generalized AC-OPF consists of building a convergent sequence of convex optimizations containing only linear constraints and shows good computational scaling to larger systems. The approach is illustrated on single- and multi-scenario examples of the Matpower case-30 model.

  18. Enhancing power transfer capability through flexible AC transmission system devices:a review

    Institute of Scientific and Technical Information of China (English)

    Fadi M ALBATSH; Saad MEKHILEF; Shameem AHMAD; H MOKHLIS; M A HASSAN

    2015-01-01

    Global demand for power has significantly increased, but power generation and transmission capacities have not increased proportionally with this demand. As a result, power consumers suffer from various problems, such as voltage and frequency instability and power quality issues. To overcome these problems, the capacity for available power transfer of a transmission network should be enhanced. Researchers worldwide have addressed this issue by using flexible AC transmission system (FACTS) devices. We have conducted a comprehensive review of how FACTS controllers are used to enhance the avail-able transfer capability (ATC) and power transfer capability (PTC) of power system networks. This review includes a discussion of the classification of different FACTS devices according to different factors. The popularity and applications of these devices are discussed together with relevant statistics. The operating principles of six major FACTS devices and their application in increasing ATC and PTC are also presented. Finally, we evaluate the performance of FACTS devices in ATC and PTC im-provement with respect to different control algorithms.

  19. Bottom-up synthesis of graphene/polyaniline nanocomposites for flexible and transparent energy storage devices

    Science.gov (United States)

    Souza, Victor H. R.; Oliveira, Marcela M.; Zarbin, Aldo J. G.

    2017-04-01

    An innovative, single-pot synthesis for chemically producing graphene/polyaniline nanocomposites is presented. The method, which is based on chemical reactions at liquid-liquid interfaces, begins with benzene and aniline and ultimately yields nanocomposites as thin films of polyaniline mixed with graphene. These films self-assembled at the water-benzene interface are easily transferable to any kind of ordinary substrates, plastics included. Nanocomposites prepared with different polymer/graphene ratios show differentiated structures and morphologies, resulting in excellent pseudocapacitive behaviors (specific capacitance of 267.2 F cm-3). The construction of all-solid, transparent, and flexible supercapacitor device from this nanocomposite is also presented.

  20. Highly reliable top-gated thin-film transistor memory with semiconducting, tunneling, charge-trapping, and blocking layers all of flexible polymers.

    Science.gov (United States)

    Wang, Wei; Hwang, Sun Kak; Kim, Kang Lib; Lee, Ju Han; Cho, Suk Man; Park, Cheolmin

    2015-05-27

    The core components of a floating-gate organic thin-film transistor nonvolatile memory (OTFT-NVM) include the semiconducting channel layer, tunneling layer, floating-gate layer, and blocking layer, besides three terminal electrodes. In this study, we demonstrated OTFT-NVMs with all four constituent layers made of polymers based on consecutive spin-coating. Ambipolar charges injected and trapped in a polymer electret charge-controlling layer upon gate program and erase field successfully allowed for reliable bistable channel current levels at zero gate voltage. We have observed that the memory performance, in particular the reliability of a device, significantly depends upon the thickness of both blocking and tunneling layers, and with an optimized layer thickness and materials selection, our device exhibits a memory window of 15.4 V, on/off current ratio of 2 × 10(4), read and write endurance cycles over 100, and time-dependent data retention of 10(8) s, even when fabricated on a mechanically flexible plastic substrate.

  1. Analogue spin-orbit torque device for artificial-neural-network-based associative memory operation

    Science.gov (United States)

    Borders, William A.; Akima, Hisanao; Fukami, Shunsuke; Moriya, Satoshi; Kurihara, Shouta; Horio, Yoshihiko; Sato, Shigeo; Ohno, Hideo

    2017-01-01

    We demonstrate associative memory operations reminiscent of the brain using nonvolatile spintronics devices. Antiferromagnet-ferromagnet bilayer-based Hall devices, which show analogue-like spin-orbit torque switching under zero magnetic fields and behave as artificial synapses, are used. An artificial neural network is used to associate memorized patterns from their noisy versions. We develop a network consisting of a field-programmable gate array and 36 spin-orbit torque devices. An effect of learning on associative memory operations is successfully confirmed for several 3 × 3-block patterns. A discussion on the present approach for realizing spintronics-based artificial intelligence is given.

  2. Separate groups of dopamine neurons innervate caudate head and tail encoding flexible and stable value memories.

    Science.gov (United States)

    Kim, Hyoung F; Ghazizadeh, Ali; Hikosaka, Okihide

    2014-01-01

    Dopamine (DA) neurons are thought to be critical for reward value-based learning by modifying synaptic transmissions in the striatum. Yet, different regions of the striatum seem to guide different kinds of learning. Do DA neurons contribute to the regional differences of the striatum in learning? As a first step to answer this question, we examined whether the head and tail of the caudate nucleus of the monkey (Macaca mulatta) receive inputs from the same or different DA neurons. We chose these caudate regions because we previously showed that caudate head neurons learn values of visual objects quickly and flexibly, whereas caudate tail neurons learn object values slowly but retain them stably. Here we confirmed the functional difference by recording single neuronal activity while the monkey performed the flexible and stable value tasks, and then injected retrograde tracers in the functional domains of caudate head and tail. The projecting dopaminergic neurons were identified using tyrosine hydroxylase immunohistochemistry. We found that two groups of DA neurons in the substantia nigra pars compacta project largely separately to the caudate head and tail. These groups of DA neurons were mostly separated topographically: head-projecting neurons were located in the rostral-ventral-medial region, while tail-projecting neurons were located in the caudal-dorsal-lateral regions of the substantia nigra. Furthermore, they showed different morphological features: tail-projecting neurons were larger and less circular than head-projecting neurons. Our data raise the possibility that different groups of DA neurons selectively guide learning of flexible (short-term) and stable (long-term) memories of object values.

  3. Separate groups of dopamine neurons innervate caudate head and tail encoding flexible and stable value memories

    Directory of Open Access Journals (Sweden)

    Hyoung F Kim

    2014-10-01

    Full Text Available Dopamine neurons are thought to be critical for reward value-based learning by modifying synaptic transmissions in the striatum. Yet, different regions of the striatum seem to guide different kinds of learning. Do dopamine neurons contribute to the regional differences of the striatum in learning? As a first step to answer this question, we examined whether the head and tail of the caudate nucleus of the monkey (Macaca mulatta receive inputs from the same or different dopamine neurons. We chose these caudate regions because we previously showed that caudate head neurons learn values of visual objects quickly and flexibly, whereas caudate tail neurons learn object values slowly but retain them stably. Here we confirmed the functional difference by recording single neuronal activity while the monkey performed the flexible and stable value tasks, and then injected retrograde tracers in the functional domains of caudate head and tail. The projecting dopaminergic neurons were identified using tyrosine hydroxylase immunohistochemistry. We found that two groups of dopamine neurons in the substantia nigra pars compacta project largely separately to the caudate head and tail. These groups of dopamine neurons were mostly separated topographically: head-projecting neurons were located in the rostral-ventral-medial region, while tail-projecting neurons were located in the caudal-dorsal-lateral regions of the substantia nigra. Furthermore, they showed different morphological features: tail-projecting neurons were larger and less circular than head-projecting neurons. Our data raise the possibility that different groups of dopamine neurons selectively guide learning of flexible (short-term and stable (long-term memories of object values.

  4. Magnetic Resonance Flow Velocity and Temperature Mapping of a Shape Memory Polymer Foam Device

    Energy Technology Data Exchange (ETDEWEB)

    Small IV, W; Gjersing, E; Herberg, J L; Wilson, T S; Maitland, D J

    2008-10-29

    Interventional medical devices based on thermally responsive shape memory polymer (SMP) are under development to treat stroke victims. The goals of these catheter-delivered devices include re-establishing blood flow in occluded arteries and preventing aneurysm rupture. Because these devices alter the hemodynamics and dissipate thermal energy during the therapeutic procedure, a first step in the device development process is to investigate fluid velocity and temperature changes following device deployment. A laser-heated SMP foam device was deployed in a simplified in vitro vascular model. Magnetic resonance imaging (MRI) techniques were used to assess the fluid dynamics and thermal changes associated with device deployment. Spatial maps of the steady-state fluid velocity and temperature change inside and outside the laser-heated SMP foam device were acquired. Though non-physiological conditions were used in this initial study, the utility of MRI in the development of a thermally-activated SMP foam device has been demonstrated.

  5. Construction and Operation of Three-Dimensional Memory and Logic Molecular Devices and Circuits

    Science.gov (United States)

    2013-07-01

    decrease in measured current. “Traditional” NDR devices such as resonant tunnel diodes (RTD) or Gunn diodes , are commonly made of III-V...and memory devices in the form of resonant tunnel diodes (RTDs) used in the pre- CMOS era to construct digital circuits but with prohibitive fabrication...alternative material systems. Indeed, organic electronic devices such as field effect transistors, diodes , rectifiers and nanowires have been recently

  6. Role of the hippocampus in memory formation: restorative encoding memory integration neural device as a cognitive neural prosthesis.

    Science.gov (United States)

    Berger, Theodore; Song, Dong; Chan, Rosa; Shin, Dae; Marmarelis, Vasilis; Hampson, Robert; Sweatt, Andrew; Heck, Christi; Liu, Charles; Wills, Jack; Lacoss, Jeff; Granacki, John; Gerhardt, Greg; Deadwyler, Sam

    2012-01-01

    Remind, which stands for "restorative encoding memory integration neural device," is a Defense Advanced Research Projects Agency (DARPA)-sponsored program to construct the first-ever cognitive prosthesis to replace lost memory function and enhance the existing memory capacity in animals and, ultimately, in humans. Reaching this goal involves understanding something fundamental about the brain that has not been understood previously: how the brain internally codes memories. In developing a hippocampal prosthesis for the rat, we have been able to demonstrate a multiple-input, multiple- output (MIMO) nonlinear model that predicts in real time the spatiotemporal codes for specific memories required for correct performance on a standard learning/memory task, i.e., delayed-nonmatch-to-sample (DNMS) memory. The MIMO model has been tested successfully in a number of contexts; most notably, in animals with a pharmacologically disabled hippocampus, we were able to reinstate long-term memories necessary for correct DNMS behavior by substituting a MIMO model-predicted code, delivered by electrical stimulation to the hippocampus through an array of electrodes, resulting in spatiotemporal hippocampal activity that is normally generated endogenously. We also have shown that delivering the same model-predicted code to electrode-implanted control animals with a normally functioning hippocampus substantially enhances animals memory capacity above control levels. These results in rodents have formed the basis for extending the MIMO model to nonhuman primates; this is now underway as the last step of the REMIND program before developing a MIMO-based cognitive prosthesis for humans.

  7. Memory attacks on device-independent quantum cryptography.

    Science.gov (United States)

    Barrett, Jonathan; Colbeck, Roger; Kent, Adrian

    2013-01-01

    Device-independent quantum cryptographic schemes aim to guarantee security to users based only on the output statistics of any components used, and without the need to verify their internal functionality. Since this would protect users against untrustworthy or incompetent manufacturers, sabotage, or device degradation, this idea has excited much interest, and many device-independent schemes have been proposed. Here we identify a critical weakness of device-independent protocols that rely on public communication between secure laboratories. Untrusted devices may record their inputs and outputs and reveal information about them via publicly discussed outputs during later runs. Reusing devices thus compromises the security of a protocol and risks leaking secret data. Possible defenses include securely destroying or isolating used devices. However, these are costly and often impractical. We propose other more practical partial defenses as well as a new protocol structure for device-independent quantum key distribution that aims to achieve composable security in the case of two parties using a small number of devices to repeatedly share keys with each other (and no other party).

  8. Charge Carrier Transport Mechanism Based on Stable Low Voltage Organic Bistable Memory Device.

    Science.gov (United States)

    Ramana, V V; Moodley, M K; Kumar, A B V Kiran; Kannan, V

    2015-05-01

    A solution processed two terminal organic bistable memory device was fabricated utilizing films of polymethyl methacrylate PMMA/ZnO/PMMA on top of ITO coated glass. Electrical characterization of the device structure showed that the two terminal device exhibited favorable switching characteristics with an ON/OFF ratio greater than 1 x 10(4) when the voltage was swept between - 2 V and +3 V. The device maintained its state after removal of the bias voltage. The device did not show degradation after a 1-h retention test at 120 degrees C. The memory functionality was consistent even after fifty cycles of operation. The charge transport switching mechanism is discussed on the basis of carrier transport mechanism and our analysis of the data shows that the charge carrier trans- port mechanism of the device during the writing process can be explained by thermionic emission (TE) and space-charge-limited-current (SCLC) mechanism models while erasing process could be explained by the FN tunneling mechanism. This demonstration provides a class of memory devices with the potential for low-cost, low-power consumption applications, such as a digital memory cell.

  9. Shape-memory polymer foam device for treating aneurysms

    Science.gov (United States)

    Ortega, Jason M.; Benett, William J.; Small, Ward; Wilson, Thomas S.; Maitland, Duncan J; Hartman, Jonathan

    2017-05-30

    A system for treating an aneurysm in a blood vessel or vein, wherein the aneurysm has a dome, an interior, and a neck. The system includes a shape memory polymer foam in the interior of the aneurysm between the dome and the neck. The shape memory polymer foam has pores that include a first multiplicity of pores having a first pore size and a second multiplicity of pores having a second pore size. The second pore size is larger than said first pore size. The first multiplicity of pores are located in the neck of the aneurysm. The second multiplicity of pores are located in the dome of the aneurysm.

  10. Evaluation of inertial devices for the control of large, flexible, space-based telerobotic arms

    Science.gov (United States)

    Montgomery, Raymond C.; Kenny, Sean P.; Ghosh, Dave; Shenhar, Joram

    1993-01-01

    Inertial devices, including sensors and actuators, offer the potential of improving the tracking of telerobotic commands for space-based robots by smoothing payload motions and suppressing vibrations. In this paper, inertial actuators (specifically, torque-wheels and reaction-masses) are studied for that potential application. Batch simulation studies are presented which show that torque-wheels can reduce the overshoot in abrupt stop commands by 82 percent for a two-link arm. For man-in-the-loop evaluation, a real-time simulator has been developed which samples a hand-controller, solves the nonlinear equations of motion, and graphically displays the resulting motion on a computer workstation. Currently, two manipulator models, a two-link, rigid arm and a single-link, flexible arm, have been studied. Results are presented which show that, for a single-link arm, a reaction-mass/torque-wheel combination at the payload end can yield a settling time of 3 s for disturbances in the first flexible mode as opposed to 10 s using only a hub motor. A hardware apparatus, which consists of a single-link, highly flexible arm with a hub motor and a torque-wheel, has been assembled to evaluate the concept and is described herein.

  11. A Facile Approach for Constructing Conductive Polymer Patterns for Application in Electrochromic Devices and Flexible Microelectrodes.

    Science.gov (United States)

    Kim, Dabum; Kim, Jeonghun; Ko, Youngsang; Shim, Kyubin; Kim, Jung Ho; You, Jungmok

    2016-12-07

    We developed a novel strategy for fabricating poly(3,4-ethylenedioxythiophene) (PEDOT) patterns on various substrates, including hydrogels, via sequential solution procedure without multistep chemical etching or lift-off processes. First, PEDOT nanothin films were prepared on a glass substrate by solution phase monomer casting and oxidative polymerization. As a second step, after UV-induced poly(ethylene glycol) (PEG) photolithography at the PEDOT/PEG interface through a photomask, the hydrogel was peeled away from the PEDOT-coated glass substrate to detach the UV-exposed PEDOT region, which left the UV nonexposed PEDOT region intact on the glass substrate, resulting in PEDOT patterns. In a final step, the PEDOT patterns were cleanly transferred from the glass to a flexible hydrogel substrate by a direct-transfer process based on a second round of gelation process. Using this strategy, PEDOT patterns on ITO glass or ITO film were used to successfully fabricate an electrochromic (EC) device that exhibited stable electrochromic switching as a function of applied potential. Furthermore, PEDOT patterns on hydrogel were used to fabricate all organic, flexible microelectrodes with good electrical properties and excellent mechanical flexibility. Importantly, the conductivity of PEDOT patterns on hydrogel (ca. 235 S cm(-1)) described here is significantly higher than that previously reported (ca. 20-70 S cm(-1)). This approach can be easily integrated into various technological fabrication steps for the development of next-generation bioelectronics systems.

  12. Direct X-ray photoconversion in flexible organic thin film devices operated below 1 V

    Science.gov (United States)

    Basiricò, Laura; Ciavatti, Andrea; Cramer, Tobias; Cosseddu, Piero; Bonfiglio, Annalisa; Fraboni, Beatrice

    2016-10-01

    The application of organic electronic materials for the detection of ionizing radiations is very appealing thanks to their mechanical flexibility, low-cost and simple processing in comparison to their inorganic counterpart. In this work we investigate the direct X-ray photoconversion process in organic thin film photoconductors. The devices are realized by drop casting solution-processed bis-(triisopropylsilylethynyl)pentacene (TIPS-pentacene) onto flexible plastic substrates patterned with metal electrodes; they exhibit a strong sensitivity to X-rays despite the low X-ray photon absorption typical of low-Z organic materials. We propose a model, based on the accumulation of photogenerated charges and photoconductive gain, able to describe the magnitude as well as the dynamics of the X-ray-induced photocurrent. This finding allows us to fabricate and test a flexible 2 × 2 pixelated X-ray detector operating at 0.2 V, with gain and sensitivity up to 4.7 × 104 and 77,000 nC mGy-1 cm-3, respectively.

  13. Flexibility and electrical stability of polyester-based device electrodes under monotonic and cyclic buckling conditions

    Energy Technology Data Exchange (ETDEWEB)

    Potoczny, G.A. [School of Metallurgy and Materials, University of Birmingham, Edgbaston, B15 2TT Birmingham (United Kingdom); Bejitual, T.S. [Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, 26506, West Virginia (United States); Abell, J.S. [School of Metallurgy and Materials, University of Birmingham, Edgbaston, B15 2TT Birmingham (United Kingdom); Sierros, K.A. [Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, 26506, West Virginia (United States); Cairns, D.R., E-mail: Darran.Cairns@mail.wvu.edu [Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, 26506, West Virginia (United States); Kukureka, S.N. [School of Metallurgy and Materials, University of Birmingham, Edgbaston, B15 2TT Birmingham (United Kingdom)

    2013-01-01

    The flexibility and electrical stability of highly conductive and transparent amorphous indium tin oxide (a-ITO) films coated on polyethylene terephthalate and polyethylene naphthalate substrates were investigated by buckling tests with in situ monitoring of the electrical resistance. Monotonic and cyclic loading tests of the ITO/polymer systems were conducted. The results show that monotonic buckling in tension is more critical for electromechanical stability of ITO films than in compression (an increase in electrical resistance was observed at a critical radius of curvature, of ∼ 3 and ∼ 1 mm, respectively for both cases investigated). In contrast, cyclic loading tests show that the compression mode is more critical than the tensile mode which may be a result of the residual stress present in the film structure. Failure of the ITO film was caused by buckling-driven delamination observed using scanning electron microscopy after the tests. The presence of residual stress could mean that buckling-driven delamination is the dominant failure mode for ITO/polymer systems under repeated flexing. In general, comparable electromechanical stability was observed in both cases. Investigating the electromechanical response of such material systems is important for polymer substrate selection and life-time prediction of flexible polyester-based electronic devices. - Highlights: ► Cyclic buckling investigation of flexible electrodes. ► Importance of ITO surface compression mode as opposed to tension. ► Role of ITO residual stresses on controlled buckling investigations.

  14. Self-Restoration by Smectic Layer Structures of Monostable Ferroelectric Liquid Crystal in Flexible Devices

    Science.gov (United States)

    Fujikake, Hideo; Sato, Hiroto; Isaka, Fumito; Murashige, Takeshi; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio

    2004-12-01

    In this paper, we discuss a self-restoration phenomenon affecting smectic layer deformation and molecular alignment in monostable ferroelectric liquid crystals used for flexible displays. First, the mechanical stability of tilted ‘bookshelf’ structures of smectic layers anchored on substrates using alignment layers was examined by precisely shearing two substrates. The microscopic texture of a monostable ferroelectric liquid crystal showed tolerance to shearing and the self-restoration was thought to be due to a smectic layer reconnection phenomenon, whereas a conventional bistable ferroelectric liquid crystal film generated alignment defects due to the tilting of the stable molecular direction. We then fabricated a flexible monostable device containing fine polymer fiber networks, where anchoring of molecularly aligned polymer fibers led to the observation of monostable liquid crystal switching. A uniform liquid crystal alignment was maintained in a 100 mm× 100 mm device even after bending more than 10000 times at a minimum radius of curvature of 20 mm, due to the enhanced shearing tolerance of the smectic layer structure.

  15. Voltage-Tunable Multicolor, Sub-1.5 V, Flexible Electrochromic Devices Based on Ion Gels.

    Science.gov (United States)

    Oh, Hwan; Seo, Dong Gyu; Yun, Tae Yong; Kim, Chan Young; Moon, Hong Chul

    2017-03-01

    Voltage-tunable multicolor electrochromic devices (ECDs) are fabricated based on flexible ion gels consisting of copolymers and ionic liquids as an electrolyte layer. Dimethyl ferrocene (dmFc) is incorporated into the gel, which serves as an anodic species. In this study, two electrochromic (EC) materials, monoheptyl viologen (MHV(+)) and diheptyl viologen (DHV(2+)), are employed and show significantly different EC behavior despite the similar chemical structure. Both MHV(+)- and DHV(2+)-containing ECDs are slightly yellowish in the bleached state, whereas the colored states are magenta and blue, respectively. All devices have good coloration efficiency of 87.5 cm(2)/C (magenta) and 91.3 cm(2)/C (blue). In addition, the required power of ∼248 μW/cm(2) (magenta) and ∼72 μW/cm(2) (blue) to maintain the colored state put the ion gel-based ECDs in a class of ultralow power consumption displays. On the basis of the distinct difference in the coloration voltage range between MHV(+) and DHV(2+), and the rubbery character of the gel, flexible ECDs showing multiple colors are demonstrated. These results imply that voltage-tunable multicolor ECDs based on the gel are attractive to functional electrochemical displays.

  16. Multicolored, Low-Power, Flexible Electrochromic Devices Based on Ion Gels.

    Science.gov (United States)

    Moon, Hong Chul; Kim, Chang-Hyun; Lodge, Timothy P; Frisbie, C Daniel

    2016-03-09

    Ion gels composed of a copolymer and a room temperature ionic liquid are versatile solid-state electrolytes with excellent features including high ionic conductivity, nonvolatility, easily tunable mechanical properties, good flexibility and solution processability. Ion gels can be functionalized by incorporating redox-active species such as electrochemiluminescent (ECL) luminophores or electrochromic (EC) dyes. Here, we enhance the functionality of EC gels for realizing multicolored EC devices (ECDs), either by controlling the chemical equilibrium between a monomer and dimer of a colored EC species, or by modifying the molecular structures of the EC species. All devices in this work are conveniently fabricated by a "cut-and-stick" strategy, and require very low power for maintaining the colored state [i.e., 90 μW/cm(2) (113 μA/cm(2) at -0.8 V) for blue, 4 μW/cm(2) (10 μA/cm(2) at -0.4 V) for green, and 32 μW/cm(2) (79 μA/cm(2) at -0.4 V) for red ECD]. We also successfully demonstrate a patterned, multicolored, flexible ECD on plastic. Overall, these results suggest that gel-based ECDs have significant potential as low power displays in printed electronics powered by thin-film batteries.

  17. Bacterial cellulose membrane as flexible substrate for organic light emitting devices

    Energy Technology Data Exchange (ETDEWEB)

    Legnani, C.; Vilani, C. [CeDO-Organic Device Center, Dimat-Dimat, Inmetro, Duque de Caxias, RJ (Brazil); Calil, V.L. [CeDO-Organic Device Center, Dimat-Dimat, Inmetro, Duque de Caxias, RJ (Brazil); LOEM-Molecular Optoelectronic Laboratory-Physics Department-PUC-Rio, Rio de Janeiro, RJ (Brazil); Barud, H.S. [Institute of Chemistry, Sao Paulo State University-UNESP, CP 355 Araraquara, SP (Brazil); Quirino, W.G. [CeDO-Organic Device Center, Dimat-Dimat, Inmetro, Duque de Caxias, RJ (Brazil); Achete, C.A. [CeDO-Organic Device Center, Dimat-Dimat, Inmetro, Duque de Caxias, RJ (Brazil); COPPE-Programa de Engenharia Metalurgica e de Materiais, UFRJ, Rio de Janeiro, RJ (Brazil); Ribeiro, S.J.L. [Institute of Chemistry, Sao Paulo State University-UNESP, CP 355 Araraquara, SP (Brazil); Cremona, M. [CeDO-Organic Device Center, Dimat-Dimat, Inmetro, Duque de Caxias, RJ (Brazil); LOEM-Molecular Optoelectronic Laboratory-Physics Department-PUC-Rio, Rio de Janeiro, RJ (Brazil)], E-mail: cremona@fis.puc-rio.br

    2008-12-01

    Bacterial cellulose (BC) membranes produced by gram-negative, acetic acid bacteria (Gluconacetobacter xylinus), were used as flexible substrates for the fabrication of Organic Light Emitting Diodes (OLED). In order to achieve the necessary conductive properties indium tin oxide (ITO) thin films were deposited onto the membrane at room temperature using radio frequency (r.f.) magnetron sputtering with an r.f. power of 30 W, at pressure of 8 mPa in Ar atmosphere without any subsequent thermal treatment. Visible light transmittance of about 40% was observed. Resistivity, mobility and carrier concentration of deposited ITO films were 4.90 x 10{sup -4} Ohm cm, 8.08 cm{sup 2}/V-s and - 1.5 x 10{sup 21} cm{sup -3}, respectively, comparable with commercial ITO substrates. In order to demonstrate the feasibility of devices based on BC membranes three OLEDs with different substrates were produced: a reference one with commercial ITO on glass, a second one with a SiO{sub 2} thin film interlayer between the BC membrane and the ITO layer and a third one just with ITO deposited directly on the BC membrane. The observed OLED luminance ratio was: 1; 0.5; 0.25 respectively, with 2400 cd/m{sup 2} as the value for the reference OLED. These preliminary results show clearly that the functionalized biopolymer, biodegradable, biocompatible bacterial cellulose membranes can be successfully used as substrate in flexible organic optoelectronic devices.

  18. Gold nanoparticle-embedded silk protein-ZnO nanorod hybrids for flexible bio-photonic devices

    Science.gov (United States)

    Gogurla, Narendar; Kundu, Subhas C.; Ray, Samit K.

    2017-04-01

    Silk protein has been used as a biopolymer substrate for flexible photonic devices. Here, we demonstrate ZnO nanorod array hybrid photodetectors on Au nanoparticle-embedded silk protein for flexible optoelectronics. Hybrid samples exhibit optical absorption at the band edge of ZnO as well as plasmonic energy due to Au nanoparticles, making them attractive for selective UV and visible wavelength detection. The device prepared on Au-silk protein shows a much lower dark current and a higher photo to dark-current ratio of ∼105 as compared to the control sample without Au nanoparticles. The hybrid device also exhibits a higher specific detectivity due to higher responsivity arising from the photo-generated hole trapping by Au nanoparticles. Sharp pulses in the transient photocurrent have been observed in devices prepared on glass and Au-silk protein substrates due to the light induced pyroelectric effect of ZnO, enabling the demonstration of self-powered photodetectors at zero bias. Flexible hybrid detectors have been demonstrated on Au-silk/polyethylene terephthalate substrates, exhibiting characteristics similar to those fabricated on rigid glass substrates. A study of the performance of photodetectors with different bending angles indicates very good mechanical stability of silk protein based flexible devices. This novel concept of ZnO nanorod array photodetectors on a natural silk protein platform provides an opportunity to realize integrated flexible and self-powered bio-photonic devices for medical applications in near future.

  19. Potential up-scaling of inkjet-printed devices for logical circuits in flexible electronics

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, Kalyan Yoti, E-mail: kalyan-yoti.mitra@mb.tu-chemnitz.de, E-mail: enrico.sowade@mb.tu-chemnitz.de; Sowade, Enrico, E-mail: kalyan-yoti.mitra@mb.tu-chemnitz.de, E-mail: enrico.sowade@mb.tu-chemnitz.de [Technische Universität Chemnitz, Department of Digital Printing and Imaging Technology, Chemnitz (Germany); Martínez-Domingo, Carme [Printed Microelectronics Group, CAIAC, Universitat Autònoma de Barcelona, Bellaterra, Spain and Nanobioelectronics and Biosensors Group, Catalan Institute of Nanotechnology (ICN), Universitat Autònoma de Barcelona, Bellaterra, Catalonia (Spain); Ramon, Eloi, E-mail: eloi.ramon@uab.cat [Printed Microelectronics Group, CAIAC, Universitat Autònoma de Barcelona, Bellaterra (Spain); Nanobioelectronics and Biosensors Group, Catalan Institute of Nanotechnology (ICN), Universitat Autònoma de Barcelona, Bellaterra, Catalonia (Spain); Carrabina, Jordi, E-mail: jordi.carrabina@uab.cat [Printed Microelectronics Group, CAIAC, Universitat Autònoma de Barcelona, Bellaterra (Spain); Gomes, Henrique Leonel, E-mail: hgomes@ualg.pt [Universidade do Algarve, Institute of Telecommunications, Faro (Portugal); Baumann, Reinhard R., E-mail: reinhard.baumann@mb.tu-chemnitz.de [Technische Universität Chemnitz, Department of Digital Printing and Imaging Technology, Chemnitz (Germany); Fraunhofer Institute for Electronic Nano Systems (ENAS), Department of Printed Functionalities, Chemnitz (Germany)

    2015-02-17

    Inkjet Technology is often mis-believed to be a deposition/patterning technology which is not meant for high fabrication throughput in the field of printed and flexible electronics. In this work, we report on the 1) printing, 2) fabrication yield and 3) characterization of exemplary simple devices e.g. capacitors, organic transistors etc. which are the basic building blocks for logical circuits. For this purpose, printing is performed first with a Proof of concept Inkjet printing system Dimatix Material Printer 2831 (DMP 2831) using 10 pL small print-heads and then with Dimatix Material Printer 3000 (DMP 3000) using 35 pL industrial print-heads (from Fujifilm Dimatix). Printing at DMP 3000 using industrial print-heads (in Sheet-to-sheet) paves the path towards industrialization which can be defined by printing in Roll-to-Roll format using industrial print-heads. This pavement can be termed as 'Bridging Platform'. This transfer to 'Bridging Platform' from 10 pL small print-heads to 35 pL industrial print-heads help the inkjet-printed devices to evolve on the basis of functionality and also in form of up-scaled quantities. The high printed quantities and yield of inkjet-printed devices justify the deposition reliability and potential to print circuits. This reliability is very much desired when it comes to printing of circuits e.g. inverters, ring oscillator and any other planned complex logical circuits which require devices e.g. organic transistors which needs to get connected in different staged levels. Also, the up-scaled inkjet-printed devices are characterized and they reflect a domain under which they can work to their optimal status. This status is much wanted for predicting the real device functionality and integration of them into a planned circuit.

  20. Potential up-scaling of inkjet-printed devices for logical circuits in flexible electronics

    Science.gov (United States)

    Mitra, Kalyan Yoti; Sowade, Enrico; Martínez-Domingo, Carme; Ramon, Eloi; Carrabina, Jordi; Gomes, Henrique Leonel; Baumann, Reinhard R.

    2015-02-01

    Inkjet Technology is often mis-believed to be a deposition/patterning technology which is not meant for high fabrication throughput in the field of printed and flexible electronics. In this work, we report on the 1) printing, 2) fabrication yield and 3) characterization of exemplary simple devices e.g. capacitors, organic transistors etc. which are the basic building blocks for logical circuits. For this purpose, printing is performed first with a Proof of concept Inkjet printing system Dimatix Material Printer 2831 (DMP 2831) using 10 pL small print-heads and then with Dimatix Material Printer 3000 (DMP 3000) using 35 pL industrial print-heads (from Fujifilm Dimatix). Printing at DMP 3000 using industrial print-heads (in Sheet-to-sheet) paves the path towards industrialization which can be defined by printing in Roll-to-Roll format using industrial print-heads. This pavement can be termed as "Bridging Platform". This transfer to "Bridging Platform" from 10 pL small print-heads to 35 pL industrial print-heads help the inkjet-printed devices to evolve on the basis of functionality and also in form of up-scaled quantities. The high printed quantities and yield of inkjet-printed devices justify the deposition reliability and potential to print circuits. This reliability is very much desired when it comes to printing of circuits e.g. inverters, ring oscillator and any other planned complex logical circuits which require devices e.g. organic transistors which needs to get connected in different staged levels. Also, the up-scaled inkjet-printed devices are characterized and they reflect a domain under which they can work to their optimal status. This status is much wanted for predicting the real device functionality and integration of them into a planned circuit.

  1. Organic bistable memory devices based on MoO3 nanoparticle embedded Alq3 structures

    Science.gov (United States)

    Abhijith, T.; Kumar, T. V. Arun; Reddy, V. S.

    2017-03-01

    Organic bistable memory devices were fabricated by embedding a thin layer of molybdenum trioxide (MoO3) between two tris-(8-hydroxyquinoline)aluminum (Alq3) layers. The device exhibited excellent switching characteristics with an ON/OFF current ratio of 1.15 × 103 at a read voltage of 1 V. The device showed repeatable write–erase capability and good stability in both the conductance states. These conductance states are non-volatile in nature and can be obtained by applying appropriate voltage pulses. The effect of MoO3 layer thickness and its location in the Alq3 matrix on characteristics of the memory device was investigated. The field emission scanning electron microscopy (FE-SEM) images of the MoO3 layer revealed the presence of isolated nanoparticles. Based on the experimental results, a mechanism has been proposed for explaining the conductance switching of fabricated devices.

  2. A novel 2-T structure memory device using a Si nanodot for embedded application

    Institute of Scientific and Technical Information of China (English)

    Yang Xiaonan; Wang Yong; Zhang Manhong; Huo Zongliang; Liu Jing; Zhang Bo; Liu Ming

    2011-01-01

    Performance and reliability ofa 2 transistor Si nanocrystal nonvolatile memory(NVM)are investigated.A good performance of the memory cell has been achieved,including a fast program/erase(P/E)speed under low voltages,an excellent data retention(maintaining for 10 years)and good endurance with a less threshold voltage shift of less than 10% after 104 P/E cycles.The data show that the device has strong potential for future embedded NVM applications.

  3. High-performance nonvolatile organic transistor memory devices using the electrets of semiconducting blends.

    Science.gov (United States)

    Chiu, Yu-Cheng; Chen, Tzu-Ying; Chen, Yougen; Satoh, Toshifumi; Kakuchi, Toyoji; Chen, Wen-Chang

    2014-08-13

    Organic nonvolatile transistor memory devices of the n-type semiconductor N,N'-bis(2-phenylethyl)-perylene-3,4:9,10-tetracarboxylic diimide (BPE-PTCDI) were prepared using various electrets (i.e., three-armed star-shaped poly[4-(diphenylamino)benzyl methacrylate] (N(PTPMA)3) and its blends with 6,6-phenyl-C61-butyric acid methyl ester (PCBM), 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pen) or ferrocene). In the device using the PCBM:N(PTPMA)3 blend electret, it changed its memory feature from a write-once-read-many (WORM) type to a flash type as the PCBM content increased and could be operated repeatedly based on a tunneling process. The large shifts on the reversible transfer curves and the hysteresis after implementing a gate bias indicated the considerable charge storage in the electret layer. On the other hand, the memory characteristics showed a flash type and a WORM characteristic, respectively, using the donor/donor electrets TIPS-pen:N(PTPMA)3 and ferrocene:N(PTPMA)3. The variation on the memory characteristics was attributed to the difference of energy barrier at the interface when different types of electret materials were employed. All the studied memory devices exhibited a long retention over 10(4) s with a highly stable read-out current. In addition, the afore-discussed memory devices by inserting another electret layer of poly(methacrylic acid) (PMAA) between the BPE-PTCDI layer and the semiconducting blend layer enhanced the write-read-erase-read (WRER) operation cycle as high as 200 times. This study suggested that the energy level and charge transfer in the blend electret had a significant effect on tuning the characteristics of nonvolatile transistor memory devices.

  4. Adaptive repair device concept with shape memory polymer

    Science.gov (United States)

    Zhao, Wei; Liu, Liwu; Lan, Xin; Su, Bo; Leng, Jinsong; Liu, Yanju

    2017-02-01

    Shape memory polymer (SMP) is a new kind of intelligent polymer, which can be activated by an external stimulus to change and subsequently recover its original shape. Due to this shape memory effect, SMP can be used in a wide range of engineering and biomedical applications. This paper details an application of SMP on manufacturing of a fracture fixation. The basic properties were characterized by dynamic mechanical analysis, and the stress relaxation and fatigue were established. An SMP-based fracture fixator was designed, analyzed, and optimized. Finally, the fixator was fabricated and the fixed effects were verified by experiment in vitro. The performance of the SMP-based fixator was excellent and proved to be a potential replacement for the traditional fracture fixator.

  5. The effectiveness of music as a mnemonic device on recognition memory for people with multiple sclerosis.

    Science.gov (United States)

    Moore, Kimberly Sena; Peterson, David A; O'Shea, Geoffrey; McIntosh, Gerald C; Thaut, Michael H

    2008-01-01

    Research shows that people with multiple sclerosis exhibit learning and memory difficulties and that music can be used successfully as a mnemonic device to aid in learning and memory. However, there is currently no research investigating the effectiveness of music mnemonics as a compensatory learning strategy for people with multiple sclerosis. Participants with clinically definitive multiple sclerosis (N = 38) were given a verbal learning and memory test. Results from a recognition memory task were analyzed that compared learning through music (n = 20) versus learning through speech (n = 18). Preliminary baseline neuropsychological data were collected that measured executive functioning skills, learning and memory abilities, sustained attention, and level of disability. An independent samples t test showed no significant difference between groups on baseline neuropsychological functioning or on recognition task measures. Correlation analyses suggest that music mnemonics may facilitate learning for people who are less impaired by the disease. Implications for future research are discussed.

  6. Spray deposition of organic electroluminescent coatings for application in flexible light emitting devices

    Directory of Open Access Journals (Sweden)

    Mariya Aleksandrova

    2015-12-01

    Full Text Available Organic electroluminescent (EL films of tris(8-hydroxyquinolinatoaluminum (Alq3 mixed with polystyrene (PS binder were produced by spray deposition. The influence of the substrate temperature on the layer’s morphology and uniformity was investigated. The deposition conditions were optimized and simple flexible light-emitting devices consisting of indium-tin oxide/Alq3:PS/aluminum were fabricated on polyethylene terephthalate (PET foil to demonstrate the advantages of the sprayed organic coatings. Same structure was produced by thermal evaporation of Alq3 film as a reference. The influence of the deposition method on the film roughness and contact resistance at the electrode interfaces for both types of structures was estimated. The results were related to the devices’ efficiency. It was found that the samples with sprayed films turn on at 4 V, which is 2 V lower in comparison to the device with thermal evaporated Alq3. The current through the sprayed device is six times higher as well (17 mA vs. 2.8 mA at 6.5 V, which can be ascribed to the lower contact resistance at the EL film/electrode interfaces. This is due to the lower surface roughness of the pulverized layers.

  7. Transfer-less flexible and transparent high-κ/metal gate germanium devices on bulk silicon (100)

    KAUST Repository

    Nassar, Joanna M.

    2014-08-01

    Flexible wearable electronics have been of great interest lately for the development of innovative future technology for various interactive applications in the field of consumer electronics and advanced healthcare, offering the promise of low-cost, lightweight, and multifunctionality. In the pursuit of this trend, high mobility channel materials need to be investigated on a flexible platform, for the development of flexible high performance devices. Germanium (Ge) is one of the most attractive alternatives for silicon (Si) for high-speed computational applications, due its higher hole and electron mobility. Thus, in this work we show a cost effective CMOS compatible process for transforming conventional rigid Ge metal oxide semiconductor capacitors (MOSCAPS) into a mechanically flexible and semi-transparent platform. Devices exhibit outstanding bendability with a bending radius of 0.24 cm, and semi-transparency up to 30 %, varying with respect to the diameter size of the release holes array.

  8. On the applicability of fluidic flexible matrix composite variable impedance materials for prosthetic and orthotic devices

    Science.gov (United States)

    Philen, M.

    2009-10-01

    The applicability of variable impedance fluidic flexible matrix composites (F2MC) is investigated for development of prosthetic and orthotic devices. The F2MC material is an innovative combination of high performance composite tubes containing high bulk modulus fluids. The new material system can potentially achieve a change in stiffness of several orders of magnitude through valve control. The F2MC material system is investigated in this research through analytical studies for active impedance control for load transfer reduction in transtibial prosthetic sockets and impedance joint control for ankle-foot orthoses (AFO). Preliminary analysis results indicate that the variable modulus system can reduce the load transfer between the limb and transtibial socket and can provide impedance tailoring for improving foot-slap in an AFO.

  9. Compact modeling of CRS devices based on ECM cells for memory, logic and neuromorphic applications

    Science.gov (United States)

    Linn, E.; Menzel, S.; Ferch, S.; Waser, R.

    2013-09-01

    Dynamic physics-based models of resistive switching devices are of great interest for the realization of complex circuits required for memory, logic and neuromorphic applications. Here, we apply such a model of an electrochemical metallization (ECM) cell to complementary resistive switches (CRSs), which are favorable devices to realize ultra-dense passive crossbar arrays. Since a CRS consists of two resistive switching devices, it is straightforward to apply the dynamic ECM model for CRS simulation with MATLAB and SPICE, enabling study of the device behavior in terms of sweep rate and series resistance variations. Furthermore, typical memory access operations as well as basic implication logic operations can be analyzed, revealing requirements for proper spike and level read operations. This basic understanding facilitates applications of massively parallel computing paradigms required for neuromorphic applications.

  10. Bipolar resistive switching characteristics in tantalum nitride-based resistive random access memory devices

    Science.gov (United States)

    Kim, Myung Ju; Jeon, Dong Su; Park, Ju Hyun; Kim, Tae Geun

    2015-05-01

    This paper reports the bipolar resistive switching characteristics of TaNx-based resistive random access memory (ReRAM). The conduction mechanism is explained by formation and rupture of conductive filaments caused by migration of nitrogen ions and vacancies; this mechanism is in good agreement with either Ohmic conduction or the Poole-Frenkel emission model. The devices exhibit that the reset voltage varies from -0.82 V to -0.62 V, whereas the set voltage ranges from 1.01 V to 1.30 V for 120 DC sweep cycles. In terms of reliability, the devices exhibit good retention (>105 s) and pulse-switching endurance (>106 cycles) properties. These results indicate that TaNx-based ReRAM devices have a potential for future nonvolatile memory devices.

  11. Bipolar resistive switching characteristics in tantalum nitride-based resistive random access memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myung Ju; Jeon, Dong Su; Park, Ju Hyun; Kim, Tae Geun, E-mail: tgkim1@korea.ac.kr [School of Electrical Engineering, Anam-dong 5ga, Sungbuk-gu, Seoul 136-701 (Korea, Republic of)

    2015-05-18

    This paper reports the bipolar resistive switching characteristics of TaN{sub x}-based resistive random access memory (ReRAM). The conduction mechanism is explained by formation and rupture of conductive filaments caused by migration of nitrogen ions and vacancies; this mechanism is in good agreement with either Ohmic conduction or the Poole-Frenkel emission model. The devices exhibit that the reset voltage varies from −0.82 V to −0.62 V, whereas the set voltage ranges from 1.01 V to 1.30 V for 120 DC sweep cycles. In terms of reliability, the devices exhibit good retention (>10{sup 5 }s) and pulse-switching endurance (>10{sup 6} cycles) properties. These results indicate that TaN{sub x}-based ReRAM devices have a potential for future nonvolatile memory devices.

  12. Flexible Bistable Smectic-A Liquid Crystal Device Using Photolithography and Photoinduced Phase Separation

    Directory of Open Access Journals (Sweden)

    Yang Lu

    2012-01-01

    Full Text Available A flexible bistable smectic-A liquid crystal (SmA LC device using pixel-isolated mode was demonstrated, in which SmA LC molecules were isolated in pixels by vertical polymer wall and horizontal polymer layer. The above microstructure was achieved by using ultraviolet (UV photolithography and photoinduced phase separation. The polymer wall was fabricated by photolithography, and then the SmA LC was encapsulated in pixels between polymer wall through UV-induced phase separation, in which the polymer wall acts as supporting structure from mechanical pressure and maintains the cell gap from bending, and the polymer layer acts as adhesive for tight attachment of two substrates. The results demonstrated that all the intrinsic bistable properties of the SmA LC are preserved, and good electrooptical characteristics such as high contrast ratio and excellent stability of the bistable states were characterized. This kind of SmA bistable flexible display has high potential to be used as electronic paper, smart switchable reflective windows, and so forth.

  13. Patterning and electronic tuning of laser scribed graphene for flexible all-carbon devices.

    Science.gov (United States)

    Strong, Veronica; Dubin, Sergey; El-Kady, Maher F; Lech, Andrew; Wang, Yue; Weiller, Bruce H; Kaner, Richard B

    2012-02-28

    Engineering a low-cost graphene-based electronic device has proven difficult to accomplish via a single-step fabrication process. Here we introduce a facile, inexpensive, solid-state method for generating, patterning, and electronic tuning of graphene-based materials. Laser scribed graphene (LSG) is shown to be successfully produced and selectively patterned from the direct laser irradiation of graphite oxide films under ambient conditions. Circuits and complex designs are directly patterned onto various flexible substrates without masks, templates, post-processing, transferring techniques, or metal catalysts. In addition, by varying the laser intensity and laser irradiation treatments, the electrical properties of LSG can be precisely tuned over 5 orders of magnitude of conductivity, a feature that has proven difficult with other methods. This inexpensive method for generating LSG on thin flexible substrates provides a mode for fabricating a low-cost graphene-based NO(2) gas sensor and enables its use as a heterogeneous scaffold for the selective growth of Pt nanoparticles. The LSG also shows exceptional electrochemical activity that surpasses other carbon-based electrodes in electron charge transfer rate as demonstrated using a ferro-/ferricyanide redox couple.

  14. Interface-engineered templates for molecular spin memory devices

    NARCIS (Netherlands)

    Raman, Karthik V.; Kamerbeek, Alexander M.; Mukherjee, Arup; Atodiresei, Nicolae; Sen, Tamal K.; Lazic, Predrag; Caciuc, Vasile; Michel, Reent; Stalke, Dietmar; Mandal, Swadhin K.; Bluegel, Stefan; Muenzenberg, Markus; Moodera, Jagadeesh S.

    2013-01-01

    The use of molecular spin state as a quantum of information for storage, sensing and computing has generated considerable interest in the context of next-generation data storage and communication devices(1,2), opening avenues for developing multifunctional molecular spintronics(3). Such ideas have

  15. Attention-deficit/hyperactivity disorder: the impact of methylphenidate on working memory, inhibition capacity and mental flexibility.

    Science.gov (United States)

    Bolfer, Cristiana; Pacheco, Sandra Pasquali; Tsunemi, Miriam Harumi; Carreira, Walter Souza; Casella, Beatriz Borba; Casella, Erasmo Barbante

    2017-04-01

    To compare children with attention-deficit/hyperactivity disorder (ADHD), before and after the use of methylphenidate, and a control group, using tests of working memory, inhibition capacity and mental flexibility. Neuropsychological tests were administrated to 53 boys, 9-12 years old: the WISC-III digit span backward, and arithmetic; Stroop Color; and Trail Making Tests. The case group included 23 boys with ADHD, who were combined type, treatment-naive, and with normal intelligence without comorbidities. The control group (n = 30) were age and gender matched. After three months on methylphenidate, the ADHD children were retested. The control group was also retested after three months. Before treatment, ADHD children had lower scores than the control group on the tests (p ≤ 0.001) and after methylphenidate had fewer test errors than before (p ≤ 0.001). Methylphenidate treatment improves the working memory, inhibitory control and mental flexibility of ADHD boys.

  16. Configurable Resistive Switching between Memory and Threshold Characteristics for Protein-Based Devices

    KAUST Repository

    Wang, Hong

    2015-05-01

    The employ of natural biomaterials as the basic building blocks of electronic devices is of growing interest for biocompatible and green electronics. Here, resistive switching (RS) devices based on naturally silk protein with configurable functionality are demonstrated. The RS type of the devices can be effectively and exactly controlled by controlling the compliance current in the set process. Memory RS can be triggered by a higher compliance current, while threshold RS can be triggered by a lower compliance current. Furthermore, two types of memory devices, working in random access and WORM modes, can be achieved with the RS effect. The results suggest that silk protein possesses the potential for sustainable electronics and data storage. In addition, this finding would provide important guidelines for the performance optimization of biomaterials based memory devices and the study of the underlying mechanism behind the RS effect arising from biomaterials. Resistive switching (RS) devices with configurable functionality based on protein are successfully achieved. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Spatially resolved Raman spectroelectrochemistry of solid-state polythiophene/viologen memory devices.

    Science.gov (United States)

    Kumar, Rajesh; Pillai, Rajesh G; Pekas, Nikola; Wu, Yiliang; McCreery, Richard L

    2012-09-12

    A three terminal molecular memory device was monitored with in situ Raman spectroscopy during bias-induced switching between two metastable states having different conductivity. The device structure is similar to that of a polythiophene field effect transistor, but ethylviologen perchlorate was added to provide a redox counter-reaction to accompany polythiophene redox reactions. The conductivity of the polythiophene layer was reversibly switched between high and low conductance states with a "write/erase" (W/E) bias, while a separate readout circuit monitored the polymer conductance. Raman spectroscopy revealed reversible polythiophene oxidation to its polaron form accompanied by a one-electron viologen reduction. "Write", "read", and "erase" operations were repeatable, with only minor degradation of response after 200 W/E cycles. The devices exhibited switching immediately after fabrication and did not require an "electroforming" step required in many types of memory devices. Spatially resolved Raman spectroscopy revealed polaron formation throughout the polymer layer, even away from the electrodes in the channel and drain regions, indicating that thiophene oxidation "propagates" by growth of the conducting polaron form away from the source electrode. The results definitively demonstrate concurrent redox reactions of both polythiophene and viologen in solid-state devices and correlate such reactions with device conductivity. The mechanism deduced from spectroscopic and electronic monitoring should guide significant improvements in memory performance.

  18. Exploration of Uninitialized Configuration Memory Space for Intrinsic Identification of Xilinx Virtex-5 FPGA Devices

    Directory of Open Access Journals (Sweden)

    Oliver Sander

    2012-01-01

    Full Text Available SRAM-based fingerprinting uses deviations in power-up behaviour caused by the CMOS fabrication process to identify distinct devices. This method is a promising technique for unique identification of physical devices. In the case of SRAM-based hardware reconfigurable devices such as FPGAs, the integrated SRAM cells are often initialized automatically at power-up, sweeping potential identification data. We demonstrate an approach to utilize unused parts of configuration memory space for device identification. Based on a total of over 200,000 measurements on nine Xilinx Virtex-5 FPGAs, we show that the retrieved values have promising properties with respect to consistency on one device, variety between different devices, and stability considering temperature variation and aging.

  19. Inkjet printing of sol-gel synthesized hydrated tungsten oxide nanoparticles for flexible electrochromic devices.

    Science.gov (United States)

    Costa, Cláudia; Pinheiro, Carlos; Henriques, Inês; Laia, César A T

    2012-03-01

    Tungsten oxide nanoparticles were synthesized via a sol-gel route using metallic tungsten as precursor, and were printed on a flexible electrode using inkjet printing in order to build solid-state electrochromic cells. Several spectroscopic techniques were used to characterize and compare tungsten oxide particles obtained from different origins. FTIR, Raman and X-ray diffraction spectroscopic measurements showed that the sol-gel synthesis described here produces nanoparticles mainly in an amorphous state with hexagonal crystalline domains and allowed the analysis of the hydration extent of those nanoparticles. The size was measured combining dynamic light scattering, sedimentation, and microscopic techniques (AFM), showing a consistent size of about 200 nm. The tungsten oxide nanoparticles were used to produce an ink formulation for application in inkjet printing. Solid-state electrochromic devices were assembled at room temperature, without sintering the tungsten oxide printed films, showing excellent contrast between on/off states. Electrochemical characterization of those films is described using cyclic voltammetry. The devices were then tested through spectroelectrochemistry by Visible/NIR absorption spectroscopy (400-2200 nm range), showing a dual spectroscopic response depending on the applied voltage. This phenomenon is attributed to the presence of two different crystalline states in accordance with results obtained from the spectroscopic characterization of the nanoparticles. The electrochromic cells had a good cycling stability showing high reversibility and a cyclability up to more than 50,000 cycles with a degradation of 25%. © 2012 American Chemical Society

  20. Synthesis of silicon nanocomposite for printable photovoltaic devices on flexible substrate

    Science.gov (United States)

    Odo, E. A.; Faremi, A. A.

    2017-06-01

    Renewed interest has been established in the preparation of silicon nanoparticles for electronic device applications. In this work, we report on the production of silicon powders using a simple ball mill and of silicon nanocomposite ink for screen-printable photovoltaic device on a flexible substrate. Bulk single crystalline silicon was milled for 25 h in the ball mill. The structural properties of the produced silicon nanoparticles were investigated using X-ray diffraction (XRD) and transmission electron microscopy. The results show that the particles remained highly crystalline, though transformed from their original single crystalline state to polycrystalline. The elemental composition using energy dispersive X-ray florescence spectroscopy (EDXRF) revealed that contamination from iron (Fe) and chromium (Cr) of the milling media and oxygen from the atmosphere were insignificant. The size distribution of the nanoparticles follows a lognormal pattern that ranges from 60 nm to about 1.2 μm and a mean particle size of about 103 nm. Electrical characterization of screen-printed PN structures of the nanocomposite formed by embedding the powder into a suitable water-soluble polymer on Kapton sheet reveals an enhanced photocurrent transport resulting from photo-induced carrier generation in the depletion region with energy greater that the Schottky barrier height at the metal-composite interface.

  1. Combining the Converse Humidity/Resistance Response Behaviors of RGO Films for Flexible Logic Devices

    KAUST Repository

    Tai, Yanlong

    2017-03-23

    Carbon nanomaterials have excellent humidity sensing performance. Here, we demonstrate that reduced-graphene-oxide- (rGO) based conductive films with different thermal reduction times have gradient and invertible humidity/electrical resistance responses: rGO films (< 11 h, negative response, regarded as a signal of “0”), rGO films (around 11-13 h, balance point) and rGO films (> 13 h, negative response, regarded as a signal of “1”). We propose a new mechanism that describes a “scale”-like model for rGO films to explain these behaviors based on contributions from Ohm-contact resistance and capacitive reactance at interplate junctions, and intrinsic resistances of the nanoplates, respectively. This mechanism is accordingly validated via a series of experiments and electrical impedance spectroscopies, which complement more classical models based on proton conductivity. To explore the practical applications of the converse humidity/resistance responses, three simple flexible logic devices were developed, i) a rGO pattern for humidity-insensitive conductive film, which has the potential to greatly improve the stability of carbon-based electrical device to humidity; ii) a Janus pattern of rGO films for gesture recognition, which is very useful to human/machine interactions; iii) a sandwich pattern of rGO films for 3-dimensional (3D) noncontact sensing, which will be complementary to existing 3D touch technique.

  2. Nanochip: a MEMS-Based Ultra-High Data Density Memory Device

    Directory of Open Access Journals (Sweden)

    Nickolai BELOV

    2009-10-01

    Full Text Available he paper provides an overview of successful development of MEMS micro-mover with large range of motion and an array of cantilevers with sharp tips (read-write heads for a probe storage device. Approaches used for integration of memory material into the MEMS process and integration of MEMS cantilever process with CMOS are briefly discussed.

  3. Realization of transient memory-loss with NiO-based resistive switching device

    Science.gov (United States)

    Hu, S. G.; Liu, Y.; Chen, T. P.; Liu, Z.; Yu, Q.; Deng, L. J.; Yin, Y.; Hosaka, Sumio

    2012-11-01

    A resistive switching device based on a nickel-rich nickel oxide thin film, which exhibits inherent learning and memory-loss abilities, is reported in this work. The conductance of the device gradually increases and finally saturates with the number of voltage pulses (or voltage sweepings), which is analogous to the behavior of the short-term and long-term memory in the human brain. Furthermore, the number of the voltage pulses (or sweeping cycles) required to achieve a given conductance state increases with the interval between two consecutive voltage pulses (or sweeping cycles), which is attributed to the heat diffusion in the material of the conductive filaments formed in the nickel oxide thin film. The phenomenon resembles the behavior of the human brain, i.e., forgetting starts immediately after an impression, a larger interval of the impressions leads to more memory loss, thus the memorization needs more impressions to enhance.

  4. Topical Nasal Anesthesia in Flexible Bronchoscopy--A Cross-Over Comparison between Two Devices.

    Directory of Open Access Journals (Sweden)

    Thomas Fuehner

    Full Text Available Topical airway anesthesia is known to improve tolerance and patient satisfaction during flexible bronchoscopy (FB. Lidocaine is commonly used, delivered as an atomized spray. The current study assesses safety and patient satisfaction for nasal anesthesia of a new atomization device during outpatient bronchoscopy in lung transplant recipients.Using a prospective, non-blinded, cross-over design, patients enrolled between 01-10-2014 and 24-11-2014 received 2% lidocaine using the standard reusable nasal atomizer (CRNA. Those enrolled between 25-11-2014 and 30-01-2015, received a disposable intranasal mucosal atomization device (DIMAD. After each procedure, the treating physician, their assistant and the patient independently rated side-effects and satisfaction, basing their responses on visual analogue scales (VAS. At their next scheduled bronchoscopy during the study period, patients then received the alternative atomizer. Written consent was obtained prior to the first bronchoscopy, and the study approved by the institutional ethics committee.Of the 252 patients enrolled between 01-10-2014 and 30-01-2015, 80 (32% received both atomizers. Physicians reported better efficacy (p = 0.001 and fewer side effects (p< = 0.001 for DIMAD in patients exposed to both procedures. Among patients with one visit, physicians and their assistants reported improved efficacy (p = 0.018, p = 0.002 and fewer side effects (p< = 0.001, p = 0.029 for the disposable atomizer, whereas patients reported no difference in efficacy or side effects (p = 0.72 and p = 0.20. No severe adverse events were noted. The cost of the reusable device was 4.08€ per procedure, compared to 3.70€ for the disposable device.Topical nasal anesthesia via a disposable intranasal mucosal atomization device (DIMAD offers comparable safety and patient comfort, compared to conventional reusable nasal atomizers (CRNA in lung transplant recipients. Procedural costs were reduced by 0.34€ per

  5. A bio-inspired memory device based on interfacing Physarum polycephalum with an organic semiconductor

    Directory of Open Access Journals (Sweden)

    Agostino Romeo

    2015-01-01

    Full Text Available The development of devices able to detect and record ion fluxes is a crucial point in order to understand the mechanisms that regulate communication and life of organisms. Here, we take advantage of the combined electronic and ionic conduction properties of a conducting polymer to develop a hybrid organic/living device with a three-terminal configuration, using the Physarum polycephalum Cell (PPC slime mould as a living bio-electrolyte. An over-oxidation process induces a conductivity switch in the polymer, due to the ionic flux taking place at the PPC/polymer interface. This behaviour endows a current-depending memory effect to the device.

  6. A bio-inspired memory device based on interfacing Physarum polycephalum with an organic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Romeo, Agostino; Dimonte, Alice; Tarabella, Giuseppe; D’Angelo, Pasquale, E-mail: dangelo@imem.cnr.it, E-mail: iannotta@imem.cnr.it; Erokhin, Victor; Iannotta, Salvatore, E-mail: dangelo@imem.cnr.it, E-mail: iannotta@imem.cnr.it [IMEM-CNR, Institute of Materials for Electronics and Magnetism-National Research Council, Parma 43124 (Italy)

    2015-01-01

    The development of devices able to detect and record ion fluxes is a crucial point in order to understand the mechanisms that regulate communication and life of organisms. Here, we take advantage of the combined electronic and ionic conduction properties of a conducting polymer to develop a hybrid organic/living device with a three-terminal configuration, using the Physarum polycephalum Cell (PPC) slime mould as a living bio-electrolyte. An over-oxidation process induces a conductivity switch in the polymer, due to the ionic flux taking place at the PPC/polymer interface. This behaviour endows a current-depending memory effect to the device.

  7. Fabrication of spray-printed organic non-volatile memory devices for low cost electronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Cha, An-Na [Soft Innovative Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology, San 101 Eunha-ri, Bongdong-eup, Wanju-gun, Jeollabuk-do (Korea, Republic of); Professional Graduate School of Flexible and Printable Electronics and Polymer Materials Fusion Research Center, Chonbuk National University, 664-14, Deokjin-dong, Deokjin-gu, Jeonju-si, Jeollabuk-do 561-756 (Korea, Republic of); Ji, Yongsung [Soft Innovative Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology, San 101 Eunha-ri, Bongdong-eup, Wanju-gun, Jeollabuk-do (Korea, Republic of); Lee, Sang-A [Soft Innovative Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology, San 101 Eunha-ri, Bongdong-eup, Wanju-gun, Jeollabuk-do (Korea, Republic of); Department of Polymer-Nano Science and Technology, Chonbuk National University, 664-14 Duckjin-dong, Duckjin-gu, Jeonju 561-756 (Korea, Republic of); Noh, Yong-Young [Department of Energy and Materials Engineering, Dongguk University, 26 Pil-dong, 3-Ga, Jung-gu, Seoul 100-715 (Korea, Republic of); Na, Seok-In [Professional Graduate School of Flexible and Printable Electronics and Polymer Materials Fusion Research Center, Chonbuk National University, 664-14, Deokjin-dong, Deokjin-gu, Jeonju-si, Jeollabuk-do 561-756 (Korea, Republic of); Bae, Sukang; Lee, Sanghyun [Soft Innovative Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology, San 101 Eunha-ri, Bongdong-eup, Wanju-gun, Jeollabuk-do (Korea, Republic of); Kim, Tae-Wook, E-mail: twkim@kist.re.kr [Soft Innovative Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology, San 101 Eunha-ri, Bongdong-eup, Wanju-gun, Jeollabuk-do (Korea, Republic of)

    2015-01-15

    Highlights: • PS:PCBM-based organic non-volatile memory devices was fabricated using spray printing. • The thickness of the film was controlled by adjusting the concentration of the PS:PCBM solutions. • The roughness of spray-printed films was poorer than that of the spin-coated film. • The minimum thickness of the printed film influenced the memory behavior more than the surface roughness. • The spray printed PS:PCBM showed excellent unipolar switching, reliability, retention, and endurance characteristics. - Abstract: We fabricated polystyrene (PS) and 6-phenyl-C61 butyric acid methyl ester (PCBM) based organic non-volatile memory devices using a spray printing technique. Due to the distinct operational properties of this technique, significant differences were observed in the macro- and microscopic features (e.g., the film quality and surface roughness) of the devices. The thickness of the film was successfully controlled by adjusting the concentration of the PS:PCBM solutions sprayed. Although the roughness of the spray-printed films was poorer than that of the spin-coated film, negligible differences were observed in the basic memory characteristics (e.g., the operation voltage range, turn on and off voltage, retention and endurance). In particular, the printing-based organic memory devices were successfully switched, as exhibited by the on/off ratio greater than two orders of magnitude at 0.3 V read voltage. The resistance state of all of the devices was maintained for more than 10{sup 4} s, indicating their non-volatile characteristics.

  8. Memory effects in a Al/Ti:HfO2/CuPc metal-oxide-semiconductor device

    Science.gov (United States)

    Tripathi, Udbhav; Kaur, Ramneek

    2016-05-01

    Metal oxide semiconductor structured organic memory device has been successfully fabricated. Ti doped hafnium oxide (Ti:HfO2) nanoparticles has been fabricated by precipitation method and further calcinated at 800 °C. Copper phthalocyanine, a hole transporting material has been utilized as an organic semiconductor. The electrical properties of the fabricated device have been studied by measuring the current-voltage and capacitance-voltage characteristics. The amount of charge stored in the nanoparticles has been calculated by using flat band condition. This simple approach for fabricating MOS memory device has opens up opportunities for the development of next generation memory devices.

  9. Memory effects in a Al/Ti:HfO{sub 2}/CuPc metal-oxide-semiconductor device

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, Udbhav, E-mail: udbhav1781996@gmail.com; Kaur, Ramneek [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (India)

    2016-05-23

    Metal oxide semiconductor structured organic memory device has been successfully fabricated. Ti doped hafnium oxide (Ti:HfO{sub 2}) nanoparticles has been fabricated by precipitation method and further calcinated at 800 °C. Copper phthalocyanine, a hole transporting material has been utilized as an organic semiconductor. The electrical properties of the fabricated device have been studied by measuring the current-voltage and capacitance-voltage characteristics. The amount of charge stored in the nanoparticles has been calculated by using flat band condition. This simple approach for fabricating MOS memory device has opens up opportunities for the development of next generation memory devices.

  10. Negative effect of Au nanoparticles on an IGZO TFT-based nonvolatile memory device

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Myunghoon; Yoo, Gwangwe; Lee, Jongtaek; Jeong, Seokwon; Roh, Yonghan; Park, Jinhong; Kwon, Namyong [Sungkyunkwan University, Suwon (Korea, Republic of); Jung, Wooshik [Stanford University, Stanford, CA (United States)

    2014-02-15

    In this letter, the electrical characteristics of nonvolatile memory devices based on back gate type indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) are investigated in terms of the Au nanoparticles (NPs) employed in the floating gate-stack of the device. The size of the Au NPs is controlled using a by 500 .deg. C annealing process after the Au thin-film deposition. The size and the roughness of the Au NPs were observed by using scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. In order to analyze the electrical properties according to Au NP size, we measured the current-voltage (I{sub D}-V{sub G}) characteristics of the nonvolatile memory devices fabricated without Au NPs and with Au NPs of various sizes. The size of the Au NP increased, so did the surface roughness of the gate. This resulted in increased carrier scattering, which subsequently degraded the on-current of the memory device. In addition, inter-diffusion between the Au and the α-IGZO through the non-uniform Al{sub 2}O{sub 3} tunneling layer seemed to further degrade the device performance.

  11. Anomalous Threshold Voltage Variability of Nitride Based Charge Storage Nonvolatile Memory Devices

    Directory of Open Access Journals (Sweden)

    Meng Chuan Lee

    2013-01-01

    Full Text Available Conventional technology scaling is implemented to meet the insatiable demand of high memory density and low cost per bit of charge storage nonvolatile memory (NVM devices. In this study, effect of technology scaling to anomalous threshold voltage ( variability is investigated thoroughly on postcycled and baked nitride based charge storage NVM devices. After long annealing bake of high temperature, cell’s variability of each subsequent bake increases within stable distribution and found exacerbate by technology scaling. Apparent activation energy of this anomalous variability was derived through Arrhenius plots. Apparent activation energy (Eaa of this anomalous variability is 0.67 eV at sub-40 nm devices which is a reduction of approximately 2 times from 110 nm devices. Technology scaling clearly aggravates this anomalous variability, and this poses reliability challenges to applications that demand strict control, for example, reference cells that govern fundamental program, erase, and verify operations of NVM devices. Based on critical evidence, this anomalous variability is attributed to lateral displacement of trapped charges in nitride storage layer. Reliability implications of this study are elucidated. Moreover, potential mitigation methods are proposed to complement technology scaling to prolong the front-runner role of nitride based charge storage NVM in semiconductor flash memory market.

  12. Novel spintronics devices for memory and logic: prospects and challenges for room temperature all spin computing

    Science.gov (United States)

    Wang, Jian-Ping

    An energy efficient memory and logic device for the post-CMOS era has been the goal of a variety of research fields. The limits of scaling, which we expect to reach by the year 2025, demand that future advances in computational power will not be realized from ever-shrinking device sizes, but rather by innovative designs and new materials and physics. Magnetoresistive based devices have been a promising candidate for future integrated magnetic computation because of its unique non-volatility and functionalities. The application of perpendicular magnetic anisotropy for potential STT-RAM application was demonstrated and later has been intensively investigated by both academia and industry groups, but there is no clear path way how scaling will eventually work for both memory and logic applications. One of main reasons is that there is no demonstrated material stack candidate that could lead to a scaling scheme down to sub 10 nm. Another challenge for the usage of magnetoresistive based devices for logic application is its available switching speed and writing energy. Although a good progress has been made to demonstrate the fast switching of a thermally stable magnetic tunnel junction (MTJ) down to 165 ps, it is still several times slower than its CMOS counterpart. In this talk, I will review the recent progress by my research group and my C-SPIN colleagues, then discuss the opportunities, challenges and some potential path ways for magnetoresitive based devices for memory and logic applications and their integration for room temperature all spin computing system.

  13. Interactions between chronic ethanol consumption and thiamine deficiency on neural plasticity, spatial memory and cognitive flexibility

    Science.gov (United States)

    Vedder, Lindsey C.; Hall, Joseph M.; Jabrouin, Kimberly R.; Savage, Lisa M.

    2015-01-01

    Background Many alcoholics display moderate to severe cognitive dysfunction accompanied by brain pathology. A factor confounded with prolonged heavy alcohol consumption is poor nutrition and many alcoholics are thiamine deficient. Thus, thiamine deficiency (TD) has emerged as a key factor underlying alcohol–related brain damage (ARBD). TD in humans can lead to Wernicke Encephalitis that can progress into Wernicke–Korsakoff Syndrome and these disorders have a high prevalence among alcoholics. Animal models are critical for determining the exact contributions of ethanol- and TD-induced neurotoxicity, as well as the interactions of those factors to brain and cognitive dysfunction. Methods Adult rats were randomly assigned to one of six treatment conditions: Chronic ethanol treatment (CET) where rats consumed a 20% v/v solution of ethanol over 6 months; Severe pyrithiamine-induced TD (PTD-MAS); Moderate PTD (PTD-EAS); Moderate PTD followed by CET (PTD-CET); Moderate PTD during CET (CET-PTD); Pair-fed control (PF). After recovery from treatment, all rats were tested on spontaneous alternation and attentional set-shifting. After behavioral testing, brains were harvested for determination of mature brain-derived neurotrophic factor (BDNF) and thalamic pathology. Results Moderate TD combined with CET, regardless of treatment order, produced significant impairments in spatial memory, cognitive flexibility and reductions in brain plasticity as measured by BDNF levels in the frontal cortex and hippocampus. These alterations are greater than those seen in moderate TD alone and the synergistic effects of moderate TD with CET leads to a unique cognitive profile. However, CET did not exacerbate thalamic pathology seen after moderate TD. Conclusions These data support the emerging theory that subclinical TD during chronic heavy alcohol consumption is critical for the development of significant cognitive impairment associated with ARBD. PMID:26419807

  14. Flexible, transparent and ultra-broadband photodetector based on large-area WSe2 film for wearable devices.

    Science.gov (United States)

    Zheng, Zhaoqiang; Zhang, Tanmei; Yao, Jiandomg; Zhang, Yi; Xu, Jiarui; Yang, Guowei

    2016-06-03

    Although two-dimensional (2D) materials have attracted considerable research interest for use in the development of innovative wearable optoelectronic systems, the integrated optoelectronic performance of 2D materials photodetectors, including flexibility, transparency, broadband response and stability in air, remains quite low to date. Here, we demonstrate a flexible, transparent, high-stability and ultra-broadband photodetector made using large-area and highly-crystalline WSe2 films that were prepared by pulsed-laser deposition (PLD). Benefiting from the 2D physics of WSe2 films, this device exhibits excellent average transparency of 72% in the visible range and superior photoresponse characteristics, including an ultra-broadband detection spectral range from 370 to 1064 nm, reversible photoresponsivity approaching 0.92 A W(-1), external quantum efficiency of up to 180% and a relatively fast response time of 0.9 s. The fabricated photodetector also demonstrates outstanding mechanical flexibility and durability in air. Also, because of the wide compatibility of the PLD-grown WSe2 film, we can fabricate various photodetectors on multiple flexible or rigid substrates, and all these devices will exhibit distinctive switching behavior and superior responsivity. These indicate a possible new strategy for the design and integration of flexible, transparent and broadband photodetectors based on large-area WSe2 films, with great potential for practical applications in the wearable optoelectronic devices.

  15. ITO-Free Solution-Processed Flexible Electrochromic Devices Based on PEDOT:PSS as Transparent Conducting Electrode.

    Science.gov (United States)

    Singh, Rekha; Tharion, Joseph; Murugan, Sengottaiyan; Kumar, Anil

    2017-06-14

    Electrochromic devices (ECDs) are emerging as novel technology for various applications ranging from commercialized smart window glasses, goggles, and autodimming rear view mirrors to uncommon yet more sophisticated applications such as infrared camouflage in military and thermal control in space satellites. The development of low-power, lightweight, inexpensive, and flexible devices is the need of the hour. In this respect, utilizing PEDOT:PSS as transparent conducting electrode (TCE) to replace indium tin oxide (ITO) and metal based TCEs for ECDs is a promising solution for the aforementioned requirements. In this work we have demonstrated the performance of PEDOT:PSS films coated on flexible substrates, treated with PTSA-DMSO, as TCEs for ECD applications and their comparison with that of ITO based ECDs. The PEDOT:PSS based flexible TCEs used in this study have conductivity of 1400-1500 S·cm(-1) and figure of merit (FoM) of 70-77. The process of increasing the conductivity of PEDOT:PSS films also led to the broadening of the conducting potential window (CPW), which is important for electrochemical applications of PEDOT:PSS when used as a stand-alone electrode. More than achieving a comparable electrochromic contrast, switching time, and coloration efficiency with respect to the ITO based ECDs, PEDOT:PSS devices also had the added advantage of good mechanical flexibility. These devices demonstrated superior stability during electrochemical cycling and multiple mechanical bending tests, making them an inexpensive alternative to the costly ITO based ECD technology.

  16. SEMICONDUCTOR DEVICES Density-controllable nonvolatile memory devices having metal nanocrystals through chemical synthesis and assembled by spin-coating technique

    Science.gov (United States)

    Guangli, Wang; Yubin, Chen; Yi, Shi; Lin, Pu; Lijia, Pan; Rong, Zhang; Youdou, Zheng

    2010-12-01

    A novel two-step method is employed, for the first time, to fabricate nonvolatile memory devices that have metal nanocrystals. First, size-averaged Au nanocrystals are synthesized chemically; second, they are assembled into memory devices by a spin-coating technique at room temperature. This attractive approach makes it possible to tailor the diameter and control the density of nanocrystals individually. In addition, processes at room temperature prevent Au diffusion, which is a main concern for the application of metal nanocrystal-based memory. The experimental results, both the morphology characterization and the electrical measurements, reveal that there is an optimum density of nanocrystal monolayer to balance between long data retention and a large hysteresis memory window. At the same time, density-controllable devices could also feed the preferential emphasis on either memory window or retention time. All these facts confirm the advantages and novelty of our two-step method.

  17. Feasibility study of molecular memory device based on DNA using methylation to store information

    Science.gov (United States)

    Jiang, Liming; Qiu, Wanzhi; Al-Dirini, Feras; Hossain, Faruque M.; Evans, Robin; Skafidas, Efstratios

    2016-07-01

    DNA, because of its robustness and dense information storage capability, has been proposed as a potential candidate for next-generation storage media. However, encoding information into the DNA sequence requires molecular synthesis technology, which to date is costly and prone to synthesis errors. Reading the DNA strand information is also complex. Ideally, DNA storage will provide methods for modifying stored information. Here, we conduct a feasibility study investigating the use of the DNA 5-methylcytosine (5mC) methylation state as a molecular memory to store information. We propose a new 1-bit memory device and study, based on the density functional theory and non-equilibrium Green's function method, the feasibility of electrically reading the information. Our results show that changes to methylation states lead to changes in the peak of negative differential resistance which can be used to interrogate memory state. Our work demonstrates a new memory concept based on methylation state which can be beneficial in the design of next generation DNA based molecular electronic memory devices.

  18. Mice Overexpressing Type 1 Adenylyl Cyclase Show Enhanced Spatial Memory Flexibility in the Absence of Intact Synaptic Long-Term Depression

    Science.gov (United States)

    Zhang, Ming; Wang, Hongbing

    2013-01-01

    There is significant interest in understanding the contribution of intracellular signaling and synaptic substrates to memory flexibility, which involves new learning and suppression of obsolete memory. Here, we report that enhancement of Ca[superscript 2+]-stimulated cAMP signaling by overexpressing type 1 adenylyl cyclase (AC1) facilitated…

  19. Next generation Associative Memory devices for the FTK tracking processor of the ATLAS experiment

    CERN Document Server

    Andreani, A; The ATLAS collaboration; Beccherle, B; Beretta, M; Citterio, M; Crescioli, F; Colombo, A; Giannetti, P; Liberali, V; Shojaii, J; Stabile, A

    2013-01-01

    The AMchip is a VLSI device that implements the associative memory function, a special content addressable memory specifically designed for high energy physics applications and first used in the CDF experiment at Tevatron. The 4th generation of AMchip has been developed for the core pattern recognition stage of the Fast TracKer (FTK) processor: a hardware processor for online reconstruction of particle trajectories at the ATLAS experiment at LHC. We present the architecture, design considerations, power consumption and performance measurements of the 4th generation of AMchip. We present also the design innovations toward the 5th generation and the first prototype results.

  20. Design and verification of a shape memory polymer peripheral occlusion device.

    Science.gov (United States)

    Landsman, Todd L; Bush, Ruth L; Glowczwski, Alan; Horn, John; Jessen, Staci L; Ungchusri, Ethan; Diguette, Katelin; Smith, Harrison R; Hasan, Sayyeda M; Nash, Daniel; Clubb, Fred J; Maitland, Duncan J

    2016-10-01

    Shape memory polymer foams have been previously investigated for their safety and efficacy in treating a porcine aneurysm model. Their biocompatibility, rapid thrombus formation, and ability for endovascular catheter-based delivery to a variety of vascular beds makes these foams ideal candidates for use in numerous embolic applications, particularly within the peripheral vasculature. This study sought to investigate the material properties, safety, and efficacy of a shape memory polymer peripheral embolization device in vitro. The material characteristics of the device were analyzed to show tunability of the glass transition temperature (Tg) and the expansion rate of the polymer to ensure adequate time to deliver the device through a catheter prior to excessive foam expansion. Mechanical analysis and flow migration studies were performed to ensure minimal risk of vessel perforation and undesired thromboembolism upon device deployment. The efficacy of the device was verified by performing blood flow studies that established affinity for thrombus formation and blood penetration throughout the foam and by delivery of the device in an ultrasound phantom that demonstrated flow stagnation and diversion of flow to collateral pathways.

  1. 4D Printing of Shape Memory-Based Personalized Endoluminal Medical Devices.

    Science.gov (United States)

    Zarek, Matt; Mansour, Nicola; Shapira, Shir; Cohn, Daniel

    2017-01-01

    The convergence of additive manufacturing and shape-morphing materials is promising for the advancement of personalized medical devices. The capability to transform 3D objects from one shape to another, right off the print bed, is known as 4D printing. Shape memory thermosets can be tailored to have a range of thermomechanical properties favorable to medical devices, but processing them is a challenge because they are insoluble and do not flow at any temperature. This study presents here a strategy to capitalize on a series of medical imaging modalities to construct a printable shape memory endoluminal device, exemplified by a tracheal stent. A methacrylated polycaprolactone precursor with a molecular weight of 10 000 g mol(-1) is printed with a UV-LED stereolithography printer based on anatomical data. This approach converges with the zeitgeist of personalized medicine and it is anticipated that it will broadly expand the application of shape memory-exhibiting biomedical devices to myriad clinical indications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Application of nanomaterials in two-terminal resistive-switching memory devices

    Directory of Open Access Journals (Sweden)

    Jianyong Ouyang

    2010-05-01

    Full Text Available Nanometer materials have been attracting strong attention due to their interesting structure and properties. Many important practical applications have been demonstrated for nanometer materials based on their unique properties. This article provides a review on the fabrication, electrical characterization, and memory application of two-terminal resistive-switching devices using nanomaterials as the active components, including metal and semiconductor nanoparticles (NPs, nanotubes, nanowires, and graphenes. There are mainly two types of device architectures for the two-terminal devices with NPs. One has a triple-layer structure with a metal film sandwiched between two organic semiconductor layers, and the other has a single polymer film blended with NPs. These devices can be electrically switched between two states with significant different resistances, i.e. the ‘ON’ and ‘OFF’ states. These render the devices important application as two-terminal non-volatile memory devices. The electrical behavior of these devices can be affected by the materials in the active layer and the electrodes. Though the mechanism for the electrical switches has been in argument, it is generally believed that the resistive switches are related to charge storage on the NPs. Resistive switches were also observed on crossbars formed by nanotubes, nanowires, and graphene ribbons. The resistive switches are due to nanoelectromechanical behavior of the materials. The Coulombic interaction of transient charges on the nanomaterials affects the configurable gap of the crossbars, which results into significant change in current through the crossbars. These nanoelectromechanical devices can be used as fast-response and high-density memory devices as well. Dr. Jianyong Ouyang received his bachelor degree from the Tsinghua University in Beijing, China, and MSc from the Institute of Chemistry, Chinese Academy of Science. He received his PhD from the Institute for Molecular

  3. Microstructural effect of gadolinium oxide nanocrystals upon annealing on electrical properties of memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Michael R.S. [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Liu, Chuan-Pu, E-mail: cpliu@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China); Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China); Wang, Jer-Chyi; Chen, Yu-Kai; Lai, Chao-Sung [Department of Electronic Engineering, Chang-Gung University, Kweishan 333, Taoyuan, Taiwan (China); Fang, Yu-Ching; Shu, Li [Materials and Electro-Optics Research Division, Chung Shan Institute of Science and Technology, Longtan 325, Taoyuan, Taiwan (China)

    2012-06-30

    The microstructure evolution of sputtered gadolinium oxide nanocrystal (NC) memory devices upon annealing has been characterized in detail by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). TEM results indicate that the as-deposited film is composed of metallic Gd clusters embedded in an amorphous Gd{sub x}O{sub y} matrix. The Gd clusters undergo phase transformation to oxide NCs upon annealing, reaching a maximum density of 7.9-9.1 Multiplication-Sign 10{sup 11} cm{sup -2} at 850 Degree-Sign C, which is consistent with the largest memory window width. Upon annealing at even higher temperature, TEM diffraction patterns and XPS composition profiles indicate apparent Si diffusion into the NC layer, probably from the SiO{sub 2} tunneling oxide or the Si substrate, leading to the formation of gadolinium silicate NCs. The presence of silicate NCs gradually deteriorates the device performance due to the reduction of barrier confinement for stored charges, although the dot density is only marginally decreased. The results suggest that the optimum memory device performance is dominated by not only the most considered size and density of NCs, but also the composition and phase inside. - Highlights: Black-Right-Pointing-Pointer Memory devices with gadolinium oxide nanocrystals have been realized. Black-Right-Pointing-Pointer X-ray photoelectron spectroscopy shows annealing-induced interdiffusion of Si. Black-Right-Pointing-Pointer Transmission electron microscopy indicates the formation of gadolinium silicate. Black-Right-Pointing-Pointer Migrating Si from substrate can further modify NC phase upon annealing. Black-Right-Pointing-Pointer Both nanocrystal density and phase influence the device performance.

  4. Magnetic resonance flow velocity and temperature mapping of a shape memory polymer foam device

    Directory of Open Access Journals (Sweden)

    Wilson Thomas S

    2009-12-01

    Full Text Available Abstract Background Interventional medical devices based on thermally responsive shape memory polymer (SMP are under development to treat stroke victims. The goals of these catheter-delivered devices include re-establishing blood flow in occluded arteries and preventing aneurysm rupture. Because these devices alter the hemodynamics and dissipate thermal energy during the therapeutic procedure, a first step in the device development process is to investigate fluid velocity and temperature changes following device deployment. Methods A laser-heated SMP foam device was deployed in a simplified in vitro vascular model. Magnetic resonance imaging (MRI techniques were used to assess the fluid dynamics and thermal changes associated with device deployment. Results Spatial maps of the steady-state fluid velocity and temperature change inside and outside the laser-heated SMP foam device were acquired. Conclusions Though non-physiological conditions were used in this initial study, the utility of MRI in the development of a thermally-activated SMP foam device has been demonstrated.

  5. A flexible and biocompatible triboelectric nanogenerator with tunable internal resistance for powering wearable devices

    Science.gov (United States)

    Zhu, Yanbo; Yang, Bin; Liu, Jingquan; Wang, Xingzhao; Wang, Luxian; Chen, Xiang; Yang, Chunsheng

    2016-02-01

    Recently, triboelectric energy nanogenerators (TENGs) have been paid the most attention by many researchers to convert mechanical energy into electrical energy. TENGs usually have a simple structure and a high output voltage. However, their high internal resistance results in low output power. In this work, we propose a flexible triboelectric energy nanogenerator with the double-side tribological layers of polydimethlysiloxane (PDMS) and PDMS/multiwall carbon nanotube (MWCNT). MWCNTs with different concentrations have been doped into PDMS to tune the internal resistance of triboelectric nanogenerator and optimize its output power. The dimension of the fabricated prototype is ~3.6 cm3. Three-axial force sensor is used to monitor the applied vertical forces on the device under vertical contact-separation working mode. The Prototype with 10 wt% MWCNT (Prototype I) produces higher output voltage than one with 2 wt% MWCNT (Prototype II) due to its higher dielectric parameter measured by LRC impedance analyzer. The triboelectric output voltages of Prototype I and Prototype II are 30 V and 25 V under the vertical force of 3.0 N, respectively. Their maximum triboelectric output powers are ~130 μW at 6 MΩ and ~120 μW at 8.6 MΩ under vertical forces, respectively.

  6. Enhanced thermal stability of RuO2/polyimide interface for flexible device applications

    Science.gov (United States)

    Music, Denis; Schmidt, Paul; Chang, Keke

    2017-09-01

    We have studied the thermal stability of RuO2/polyimide (Kapton) interface using experimental and theoretical methods. Based on calorimetric and spectroscopic analyses, this inorganic–organic system does not exhibit any enthalpic peaks as well as all bonds in RuO2 and Kapton are preserved up to 500 °C. In addition, large-scale density functional theory based molecular dynamics, carried out in the same temperature range, validates the electronic structure and points out that numerous Ru–C and a few Ru–O covalent/ionic bonds form across the RuO2/Kapton interface. This indicates strong adhesion, but there is no evidence of Kapton degradation upon thermal excitation. Furthermore, RuO2 does not exhibit any interfacial bonds with N and H in Kapton, providing additional evidence for the thermal stability notion. It is suggested that the RuO2/Kapton interface is stable due to aromatic architecture of Kapton. This enhanced thermal stability renders Kapton an appropriate polymeric substrate for RuO2 containing systems in various applications, especially for flexible microelectronic and energy devices.

  7. Magnetic optical sensor particles: a flexible analytical tool for microfluidic devices.

    Science.gov (United States)

    Ungerböck, Birgit; Fellinger, Siegfried; Sulzer, Philipp; Abel, Tobias; Mayr, Torsten

    2014-05-21

    In this study we evaluate magnetic optical sensor particles (MOSePs) with incorporated sensing functionalities regarding their applicability in microfluidic devices. MOSePs can be separated from the surrounding solution to form in situ sensor spots within microfluidic channels, while read-out is accomplished outside the chip. These magnetic sensor spots exhibit benefits of sensor layers (high brightness and convenient usage) combined with the advantages of dispersed sensor particles (ease of integration). The accumulation characteristics of MOSePs with different diameters were investigated as well as the in situ sensor spot stability at varying flow rates. Magnetic sensor spots were stable at flow rates specific to microfluidic applications. Furthermore, MOSePs were optimized regarding fiber optic and imaging read-out systems, and different referencing schemes were critically discussed on the example of oxygen sensors. While the fiber optic sensing system delivered precise and accurate results for measurement in microfluidic channels, limitations due to analyte consumption were found for microscopic oxygen imaging. A compensation strategy is provided, which utilizes simple pre-conditioning by exposure to light. Finally, new application possibilities were addressed, being enabled by the use of MOSePs. They can be used for microscopic oxygen imaging in any chip with optically transparent covers, can serve as flexible sensor spots to monitor enzymatic activity or can be applied to form fixed sensor spots inside microfluidic structures, which would be inaccessible to integration of sensor layers.

  8. Development of a flexible and bendable vibrotactile actuator based on wave-shaped poly(vinyl chloride)/acetyl tributyl citrate gels for wearable electronic devices

    Science.gov (United States)

    Park, Won-Hyeong; Bae, Jin Woo; Shin, Eun-Jae; Kim, Sang-Youn

    2016-11-01

    The paradigm of consumer electronic devices is being shifted from rigid hand-held devices to flexible/wearable devices in search of benefits such as enhanced usability and portability, excellent wear characteristics, and more functions in less space. However, the fundamental incompatibility of flexible/wearable devices and a rigid actuator brought forth a new issue obstructing commercialization of flexible/wearable devices. In this paper, we propose a new wave-shaped eco-friendly PVC gel, and a new flexible and bendable vibrotactile actuator that could easily be applied to wearable electronic devices. We explain the vibration mechanism of the proposed vibrotactile actuator and investigate its influence on the content of plasticizer for the performance of the proposed actuator. An experiment for measuring vibrational amplitude was conducted over a wide frequency range. The experiment clearly showed that the proposed vibrotactile actuator could create a variety of haptic sensations in wearable devices.

  9. The influence of Ti doping and annealing on Ce2Ti2O7 flash memory devices

    Science.gov (United States)

    Kao, Chyuan Haur; Chen, Su Zhien; Luo, Yang; Chiu, Wang Ting; Chiu, Shih Wei; Chen, I. Chien; Lin, Chan-Yu; Chen, Hsiang

    2017-02-01

    In this research, a CeO2 film with Ti doping was used as a trapping layer in metal oxide high-K-oxide-Si (MOHOS)-type memory devices. Since incorporation of Ti atoms into the film could fix dangling bonds and defects, the Ce2Ti2O7 trapping layer with annealing treatment could have a larger memory window and a faster programming/erasing speed. To confirm the origin, multiple material analyses indicate that annealing at an appropriate temperature and Ti doping could enhance crystallization. The Ce2Ti2O7-based memory device is promising for future industrial flash memory applications.

  10. Analysis of operations and cyber security policies for a system of cooperating Flexible Alternating Current Transmission System (FACTS) devices.

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Laurence R.; Tejani, Bankim; Margulies, Jonathan; Hills, Jason L.; Richardson, Bryan T.; Baca, Micheal J.; Weiland, Laura

    2005-12-01

    Flexible Alternating Current Transmission Systems (FACTS) devices are installed on electric power transmission lines to stabilize and regulate power flow. Power lines protected by FACTS devices can increase power flow and better respond to contingencies. The University of Missouri Rolla (UMR) is currently working on a multi-year project to examine the potential use of multiple FACTS devices distributed over a large power system region in a cooperative arrangement in which the FACTS devices work together to optimize and stabilize the regional power system. The report describes operational and security challenges that need to be addressed to employ FACTS devices in this way and recommends references, processes, technologies, and policies to address these challenges.

  11. Fabrication of patterned flexible graphene devices via facile direct transfer of as-grown bi-layer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Park, Heun; Kim, Kyung Hoon; Yoon, Jangyeol [Department of Chemical and Biological Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Kim, Kuk Ki; Park, Seung Min [Department of Chemistry, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Ha, Jeong Sook, E-mail: jeongsha@korea.ac.kr [Department of Chemical and Biological Engineering, Korea University, Seoul 136-701 (Korea, Republic of); KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701 (Korea, Republic of)

    2015-02-15

    Highlights: • Patterned bi-layer graphene was directly transferred onto various polymer substrates by using micro-contact printing technique. • Coating of dimethylformamide onto the polydimethylsiloxane (PDMS) stamp enhanced the adhesion between the bi-layer graphene and the PDMS stamp. • Patterned graphene devices showed mechanically stable electrical properties upon repeated bending cycles. - Abstract: We report on the fabrication of patterned flexible graphene devices via a facile direct transfer of bi-layer graphene grown on alumina (Al{sub 2}O{sub 3}) substrate, and the use of Ag nanowire stickers as flexible electrodes. Patterned polydimethylsiloxane (PDMS) stamps coated with vaporized dimethylformamide (DMF) are utilized to transfer as-grown graphene directly onto a flexible polyethylene terephthalate (PET) substrate. The facile direct transfer is attributed to the enhanced adhesion of the bi-layer graphene to PDMS, due to DMF-coating, as well as the weak adhesion between the bi-layer graphene and the Al{sub 2}O{sub 3} substrate. In this way, flexible patterned graphene devices have been fabricated with Ag nanowire stickers as electrodes. Stable electrical conduction characteristics were measured over repetitive bending with a bending radius down to 5 mm.

  12. Low voltage lead titanate/Si one-transistor ferroelectric memory with good device characteristics

    Science.gov (United States)

    Sun, C. L.; Chen, S. Y.; Liao, C. C.; Chin, Albert

    2004-11-01

    We have developed one-transistor ferroelectric memory using lead titanate (PTO) as a gate dielectric directly formed on Si without any buffer layer. The PTO/Si metal-oxide-semiconductor field-effect transistor memory has shown a large threshold voltage shift of 1.6 V at only ±4V program/erase voltages. The corresponding good interface was achieved by lowering the anneal temperature to 450 °C. Besides the sharp capacitance change of 0.17μF/Vcm2, it was also evidenced by the high mobility of 169cm2/Vs close to high-κ HfO2. In addition, long retention >1000s and endurance >1011 stress cycles in the device suggested good memory characteristics.

  13. Chemical-Vapor-Deposited Graphene as Charge Storage Layer in Flash Memory Device

    Directory of Open Access Journals (Sweden)

    W. J. Liu

    2016-01-01

    Full Text Available We demonstrated a flash memory device with chemical-vapor-deposited graphene as a charge trapping layer. It was found that the average RMS roughness of block oxide on graphene storage layer can be significantly reduced from 5.9 nm to 0.5 nm by inserting a seed metal layer, which was verified by AFM measurements. The memory window is 5.6 V for a dual sweep of ±12 V at room temperature. Moreover, a reduced hysteresis at the low temperature was observed, indicative of water molecules or −OH groups between graphene and dielectric playing an important role in memory windows.

  14. Modeling of electron conduction in contact resistive random access memory devices as random telegraph noise.

    Science.gov (United States)

    Tseng, Yuan Heng; Shen, Wen Chao; Lin, Chrong Jung

    2012-04-01

    The intense development and study of resistive random access memory (RRAM) devices has opened a new era in semiconductor memory manufacturing. Resistive switching and carrier conduction inside RRAM films have become critical issues in recent years. Electron trapping/detrapping behavior is observed and investigated in the proposed contact resistive random access memory (CR-RAM) cell. Through the fitting of the space charge limiting current (SCLC) model, and analysis in terms of the random telegraph noise (RTN) model, the temperature-dependence of resistance levels and the high-temperature data retention behavior of the contact RRAM film are successfully and completely explained. Detail analyses of the electron capture and emission from the traps by forward and reverse read measurements provide further verifications for hopping conduction mechanism and current fluctuation discrepancies.

  15. Flexible MgO Barrier Magnetic Tunnel Junctions.

    Science.gov (United States)

    Loong, Li Ming; Lee, Wonho; Qiu, Xuepeng; Yang, Ping; Kawai, Hiroyo; Saeys, Mark; Ahn, Jong-Hyun; Yang, Hyunsoo

    2016-07-01

    Flexible MgO barrier magnetic tunnel junction (MTJ) devices are fabricated using a transfer printing process. The flexible MTJ devices yield significantly enhanced tunneling magnetoresistance of ≈300% and improved abruptness of switching, as residual strain in the MTJ structure is released during the transfer process. This approach could be useful for flexible electronic systems that require high-performance memory components. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. High-performance memory device using graphene oxide flakes sandwiched polymethylmethacrylate layers.

    Science.gov (United States)

    Valanarasu, S; Kulandaisamy, I; Kathalingam, A; Rhee, Jin-Koo; Vijayan, T A; Chandramohan, R

    2013-10-01

    Organic bistable devices (OBDs) using graphene oxide (GO) flakes sandwiched polymethylmethacrylate (PMMA) films were fabricated. These devices exhibited two accessible conducting states, that is, a low-conductivity (OFF) state and a high-conductivity (ON) state. The devices can be switched to ON state under a negative electrical sweep; it can also be reset to the initial OFF state by a reverse (positive) electrical sweep. Detailed I-V measurements have shown that in ITO/PMMA/GO/PMMA/Al sandwiches the resistive switching originates from the formation and rupture of conducting filaments. The ON/OFF ratio of the OBDs was approximately 5 x 10(3), reproducibility of more than 10(5) cycles, and retention time of 10(4) s. These properties show that the device is promising for high-density, low-cost memory application.

  17. Structural damping with shape-memory alloys: one class of devices

    Science.gov (United States)

    Krumme, Robert; Hayes, Jack; Sweeney, Steve

    1995-05-01

    Passive control of the dynamic response of civil structures utilizing shape-memory alloy (SMA) damping techniques is reviewed. An important class of SMA damper -- the center- tapped (CT) device -- is described. Coverage includes: (1) characterization of damping requirements and passive damping approaches for civil structures; (2) characterization of SMA material behaviors relevant to civil structural applications; (3) overview of our SMA passive damping device technology and description of the center-tapped device operation and structure; (4) precis of an experimental program conducted to verify the CT device behavior, the detailed results of which are reported in another paper by the Earthquake Engineering Research Center; (5) review of a design study of SMA passive damping for retrofit of an extant nonductile concrete building.

  18. A robust molecular platform for non-volatile memory devices with optical and magnetic responses.

    Science.gov (United States)

    Simão, Cláudia; Mas-Torrent, Marta; Crivillers, Núria; Lloveras, Vega; Artés, Juan Manuel; Gorostiza, Pau; Veciana, Jaume; Rovira, Concepció

    2011-05-01

    Bistable molecules that behave as switches in solution have long been known. Systems that can be reversibly converted between two stable states that differ in their physical properties are particularly attractive in the development of memory devices when immobilized in substrates. Here, we report a highly robust surface-confined switch based on an electroactive, persistent organic radical immobilized on indium tin oxide substrates that can be electrochemically and reversibly converted to the anion form. This molecular bistable system behaves as an extremely robust redox switch in which an electrical input is transduced into optical as well as magnetic outputs under ambient conditions. The fact that this molecular surface switch, operating at very low voltages, can be patterned and addressed locally, and also has exceptionally high long-term stability and excellent reversibility and reproducibility, makes it a very promising platform for non-volatile memory devices.

  19. Magnetic Shape Memory Alloys as smart materials for micro-positioning devices

    Directory of Open Access Journals (Sweden)

    A. Hubert

    2012-10-01

    Full Text Available In the field of microrobotics, actuators based on smart materials are predominant because of very good precision, integration capabilities and high compactness. This paper presents the main characteristics of Magnetic Shape Memory Alloys as new candidates for the design of micromechatronic devices. The thermo-magneto-mechanical energy conversion process is first presented followed by the adequate modeling procedure required to design actuators. Finally, some actuators prototypes realized at the Femto-ST institute are presented, including a push-pull bidirectional actuator. Some results on the control and performances of these devices conclude the paper.

  20. Development and process control of magnetic tunnel junctions for magnetic random access memory devices

    Science.gov (United States)

    Kula, Witold; Wolfman, Jerome; Ounadjela, Kamel; Chen, Eugene; Koutny, William

    2003-05-01

    We report on the development and process control of magnetic tunnel junctions (MTJs) for magnetic random access memory (MRAM) devices. It is demonstrated that MTJs with high magnetoresistance ˜40% at 300 mV, resistance-area product (RA) ˜1-3 kΩ μm2, low intrinsic interlayer coupling (Hin) ˜2-3 Oe, and excellent bit switching characteristics can be developed and fully integrated with complementary metal-oxide-semiconductor circuitry into MRAM devices. MTJ uniformity and repeatability level suitable for mass production has been demonstrated with the advanced processing and monitoring techniques.

  1. Interfacial behavior of resistive switching in ITO-PVK-Al WORM memory devices

    Science.gov (United States)

    Whitcher, T. J.; Woon, K. L.; Wong, W. S.; Chanlek, N.; Nakajima, H.; Saisopa, T.; Songsiriritthigul, P.

    2016-02-01

    Understanding the mechanism of resistive switching in a memory device is fundamental in order to improve device performance. The mechanism of current switching in a basic organic write-once read-many (WORM) memory device is investigated by determining the energy level alignments of indium tin oxide (ITO), poly(9-vinylcarbazole) (PVK) and aluminum (Al) using x-ray and ultraviolet photoelectron spectroscopy, current-voltage characterization and Auger depth profiling. The current switching mechanism was determined to be controlled by the interface between the ITO and the PVK. The electric field applied across the device causes the ITO from the uneven surface of the anode to form metallic filaments through the PVK, causing a shorting effect within the device leading to increased conduction. This was found to be independent of the PVK thickness, although the switch-on voltage was non-linearly dependent on the thickness. The formation of these filaments also caused the destruction of the interfacial dipole at the PVK-Al interface.

  2. Metal oxide resistive random access memory based synaptic devices for brain-inspired computing

    Science.gov (United States)

    Gao, Bin; Kang, Jinfeng; Zhou, Zheng; Chen, Zhe; Huang, Peng; Liu, Lifeng; Liu, Xiaoyan

    2016-04-01

    The traditional Boolean computing paradigm based on the von Neumann architecture is facing great challenges for future information technology applications such as big data, the Internet of Things (IoT), and wearable devices, due to the limited processing capability issues such as binary data storage and computing, non-parallel data processing, and the buses requirement between memory units and logic units. The brain-inspired neuromorphic computing paradigm is believed to be one of the promising solutions for realizing more complex functions with a lower cost. To perform such brain-inspired computing with a low cost and low power consumption, novel devices for use as electronic synapses are needed. Metal oxide resistive random access memory (ReRAM) devices have emerged as the leading candidate for electronic synapses. This paper comprehensively addresses the recent work on the design and optimization of metal oxide ReRAM-based synaptic devices. A performance enhancement methodology and optimized operation scheme to achieve analog resistive switching and low-energy training behavior are provided. A three-dimensional vertical synapse network architecture is proposed for high-density integration and low-cost fabrication. The impacts of the ReRAM synaptic device features on the performances of neuromorphic systems are also discussed on the basis of a constructed neuromorphic visual system with a pattern recognition function. Possible solutions to achieve the high recognition accuracy and efficiency of neuromorphic systems are presented.

  3. Efficient mask data preparation for variable shaped e-beam writing system focusing on memory devices

    Science.gov (United States)

    Jang, Tae H.; Lee, Jong-Bae; Shin, Jae-Pil; Yoo, Kwang-Jai; Jung, Dai-Hyun; Park, Yong-Hee; Yoo, Moon-Hyun; Kong, Jeong-Taek

    2003-12-01

    To cope with sub-100nm technology in the mask making industry, a variable shaped e-beam(VSB) writing system is one of the solutions through its high-electron voltage. The VSB writing system, however, requires a different mask data preparation comparing to the traditional raster scan writing system. Due to the differences, mask making industries are confronted with difficult problems, such as explosively increasing data volume and unpredictably growing mask making time especially for memory devices. VSB system's writing time is determined by the conversion from CAD data to VSB data. The conversion time, especially for the critical layers of memory devices, mostly depends on to what extent optimize CAD data to enhance writing system throughput. For this reason, to shorten the unpredictably growing mask making time, a data conversion tool must consider the throughput of data conversion and mask writing at the same time. To reduce the data conversion time while retaining the optimal writing time, we propose the mixed-mode data processing method, in which the hierarchical data operation is applied on memory cells and the flat data operation is applied on peripheral circuits. For each area, different fracturing strategies are applied, too. The polygon-aware fracturing method is applied to improve the CD control within memory cells, and the selective one-directional fracturing method is applied to reduce the writing time within peripheral circuits.

  4. On the Flexibility of Social Source Memory: A Test of the Emotional Incongruity Hypothesis

    Science.gov (United States)

    Bell, Raoul; Buchner, Axel; Kroneisen, Meike; Giang, Trang

    2012-01-01

    A popular hypothesis in evolutionary psychology posits that reciprocal altruism is supported by a cognitive module that helps cooperative individuals to detect and remember cheaters. Consistent with this hypothesis, a source memory advantage for faces of cheaters (better memory for the cheating context in which these faces were encountered) was…

  5. Germanium nanoparticles grown at different deposition times for memory device applications

    Energy Technology Data Exchange (ETDEWEB)

    Mederos, M., E-mail: melissa.mederos@gmail.com [Center for Semiconductor Components and Nanotechnology (CCSNano), University of Campinas (Unicamp), Rua João Pandia Calógeras 90, Campinas, CEP: 13083-870, São Paulo (Brazil); Mestanza, S.N.M. [Federal University of ABC (UFABC), Rua Santa Adélia 166, Bangu, Santo André, CEP: 09210-170, São Paulo (Brazil); Lang, R. [Institute of Science and Technology, Federal University of São Paulo (UNIFESP), Rua Talim, 330, São José dos Campos, CEP: 12231-280, São Paulo (Brazil); Doi, I.; Diniz, J.A. [Center for Semiconductor Components and Nanotechnology (CCSNano), University of Campinas (Unicamp), Rua João Pandia Calógeras 90, Campinas, CEP: 13083-870, São Paulo (Brazil); School of Electrical and Computer Engineering, University of Campinas (Unicamp), Av. Albert Einstein 400, Campinas, CEP: 13083-852, São Paulo (Brazil)

    2016-07-29

    In the present work, circular Metal-Oxide-Semiconductor capacitors with 200 μm of diameter and germanium (Ge) nanoparticles (NPs) embedded in the gate oxide are studied for memory applications. Optimal process parameters are investigated for Ge NPs growing by low pressure chemical vapor deposition at different deposition times. Photoluminescence measurements showed room-temperature size-dependent green-red region bands attributed to quantum confinement effects present in the NPs. High-frequency capacitance versus voltage measurements demonstrated the memory effects on the MOS structures due to the presence of Ge NPs in the gate oxide acting as discrete floating gates. Current versus voltage measurements confirmed the Fowler-Nordheim tunneling as the programming mechanism of the devices. - Highlights: • Ge nanoparticles with high density and uniforms sizes were obtained by LPCVD. • Room-temperature size-dependent bands of photoluminescence were observed. • MOS capacitors with Ge nanoparticles embedded in the oxide were fabricated. • Ge nanoparticles are the main responsible for the memory properties in the devices. • Fowler-Nordheim tunneling is the conduction mechanism observed on the devices.

  6. InAs quantum dots as charge storing elements for applications in flash memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Sk Masiul; Biswas, Pranab [Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302 (India); Banerji, P., E-mail: pallab@matsc.iitkgp.ernet.in [Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302 (India); Chakraborty, S. [Applied Materials Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Sector-I, Kolkata 700 064 (India)

    2015-08-15

    Graphical abstract: - Highlights: • Catalyst-free growth of InAs quantum dots was carried out on high-k ZrO{sub 2}. • Memory device with InAs quantum dots as charge storage nodes are fabricated. • Superior memory window, low leakage and reasonably good retention were observed. • Carrier transport phenomena are explained in both program and erase operations. - Abstract: InAs quantum dots (QDs) were grown by metal organic chemical vapor deposition technique to use them as charge storage nodes. Uniform QDs were formed with average diameter 5 nm and height 5–10 nm with a density of 2 × 10{sup 11} cm{sup −2}. The QDs were grown on high-k dielectric layer (ZrO{sub 2}), which was deposited onto ultra-thin GaP passivated p-GaAs (1 0 0) substrate. A charge storage device with the structure Metal/ZrO{sub 2}/InAs QDs/ZrO{sub 2}/(GaP)GaAs/Metal was fabricated. The devices containing InAs QDs exhibit superior memory window, low leakage current density along with reasonably good charge retention. A suitable electronic band diagram corresponding to programming and erasing operations was proposed to explain the operation.

  7. Inhibition, flexibility, working memory and planning in autism spectrum disorders with and without comorbid ADHD-symptoms

    Directory of Open Access Journals (Sweden)

    Schmidt Martin H

    2008-01-01

    Full Text Available Abstract Background Recent studies have not paid a great deal of attention to comorbid attention-deficit/hyperactivity disorder (ADHD symptoms in autistic children even though it is well known that almost half of children with autism spectrum disorder (ASD suffer from hyperactivity, inattention and impulsivity. The goal of this study was to evaluate and compare executive functioning (EF profiles in children with ADHD and in children with ASD with and without comorbid ADHD. Methods Children aged 6 to 18 years old with ADHD (n = 20 or ASD (High-Functioning autism or Asperger syndrome with (n = 20 and without (n = 20 comorbid ADHD and a typically developing group (n = 20 were compared on a battery of EF tasks comprising inhibition, flexibility, working memory and planning tasks. A MANOVA, effect sizes as well as correlations between ADHD-symptomatology and EF performance were calculated. Age- and IQ-corrected z scores were used. Results There was a significant effect for the factor group (F = 1.55; dF = 42; p = .02. Post-hoc analysis revealed significant differences between the ADHD and the TD group on the inhibition task for false alarms (p = .01 and between the ADHD group, the ASD+ group (p = .03, the ASD- group (p = .02 and the TD group (p = .01 for omissions. Effect sizes showed clear deficits of ADHD children in inhibition and working memory tasks. Participants with ASD were impaired in planning and flexibility abilities. The ASD+ group showed compared to the ASD- group more problems in inhibitory performance but not in the working memory task. Conclusion Our findings replicate previous results reporting impairment of ADHD children in inhibition and working memory tasks and of ASD children in planning and flexibility abilities. The ASD + group showed similarities to the ADHD group with regard to inhibitory but not to working memory deficits. Nevertheless the heterogeneity of these and previous results shows that EF assessment is not useful for

  8. Inhibition, flexibility, working memory and planning in autism spectrum disorders with and without comorbid ADHD-symptoms.

    Science.gov (United States)

    Sinzig, Judith; Morsch, Dagmar; Bruning, Nicole; Schmidt, Martin H; Lehmkuhl, Gerd

    2008-01-31

    Recent studies have not paid a great deal of attention to comorbid attention-deficit/hyperactivity disorder (ADHD) symptoms in autistic children even though it is well known that almost half of children with autism spectrum disorder (ASD) suffer from hyperactivity, inattention and impulsivity. The goal of this study was to evaluate and compare executive functioning (EF) profiles in children with ADHD and in children with ASD with and without comorbid ADHD. Children aged 6 to 18 years old with ADHD (n = 20) or ASD (High-Functioning autism or Asperger syndrome) with (n = 20) and without (n = 20) comorbid ADHD and a typically developing group (n = 20) were compared on a battery of EF tasks comprising inhibition, flexibility, working memory and planning tasks. A MANOVA, effect sizes as well as correlations between ADHD-symptomatology and EF performance were calculated. Age- and IQ-corrected z scores were used. There was a significant effect for the factor group (F = 1.55; dF = 42; p = .02). Post-hoc analysis revealed significant differences between the ADHD and the TD group on the inhibition task for false alarms (p = .01) and between the ADHD group, the ASD+ group (p = .03), the ASD- group (p = .02) and the TD group (p = .01) for omissions. Effect sizes showed clear deficits of ADHD children in inhibition and working memory tasks. Participants with ASD were impaired in planning and flexibility abilities. The ASD+ group showed compared to the ASD- group more problems in inhibitory performance but not in the working memory task. Our findings replicate previous results reporting impairment of ADHD children in inhibition and working memory tasks and of ASD children in planning and flexibility abilities. The ASD + group showed similarities to the ADHD group with regard to inhibitory but not to working memory deficits. Nevertheless the heterogeneity of these and previous results shows that EF assessment is not useful for differential diagnosis between ADHD and ASD. It might

  9. The Nano-Memory Devices of a Single Wall and Peapod Structural Carbon Nanotube Field Effect Transistor

    Science.gov (United States)

    Lee, C. H.; Kang, K. T.; Park, K. S.; Kim, M. S.; Kim, H. S.; Kim, H. G.; Fischer, J. E.; Johnson, A. T.

    2003-08-01

    The rediscovery and the memory application of single walled carbon nanotubes (SWNTs) give a new method in nanoelectronics applications. At first we will report the memory effects of a SWNT, and attempt to use this property in a memory device. To use a SWNT field effect transistor (FET) as a charge-storage memory device, the device operates by injecting electrons from the nanotube channel of a TubeFET into charge traps on the surface of the SiO2 gate dielectric, thus shifting the threshold voltage. This memory can be written and erased many times, and has a hold time of hundreds of seconds at room temperature. At second we have attempted to make a Peapod tubeFET. It is the structure that a C60 was contained within the tube and separated from it by a graphitic Van der Waals gap. I-V property of the Peapod shows semiconducting property.

  10. MIEC (mixed-ionic-electronic-conduction)-based access devices for non-volatile crossbar memory arrays

    Science.gov (United States)

    Shenoy, Rohit S.; Burr, Geoffrey W.; Virwani, Kumar; Jackson, Bryan; Padilla, Alvaro; Narayanan, Pritish; Rettner, Charles T.; Shelby, Robert M.; Bethune, Donald S.; Raman, Karthik V.; BrightSky, Matthew; Joseph, Eric; Rice, Philip M.; Topuria, Teya; Kellock, Andrew J.; Kurdi, Bülent; Gopalakrishnan, Kailash

    2014-10-01

    Several attractive applications call for the organization of memristive devices (or other resistive non-volatile memory (NVM)) into large, densely-packed crossbar arrays. While resistive-NVM devices frequently possess some degree of inherent nonlinearity (typically 3-30× contrast), the operation of large (\\gt 1000×1000 device) arrays at low power tends to require quite large (\\gt 1e7) ON-to-OFF ratios (between the currents passed at high and at low voltages). One path to such large nonlinearities is the inclusion of a distinct access device (AD) together with each of the state-bearing resistive-NVM elements. While such an AD need not store data, its list of requirements is almost as challenging as the specifications demanded of the memory device. Several candidate ADs have been proposed, but obtaining high performance without requiring single-crystal silicon and/or the high processing temperatures of the front-end-of-the-line—which would eliminate any opportunity for 3D stacking—has been difficult. We review our work at IBM Research—Almaden on high-performance ADs based on Cu-containing mixed-ionic-electronic conduction (MIEC) materials [1-7]. These devices require only the low processing temperatures of the back-end-of-the-line, making them highly suitable for implementing multi-layer cross-bar arrays. MIEC-based ADs offer large ON/OFF ratios (\\gt 1e7), a significant voltage margin {{V}m} (over which current \\lt 10 nA), and ultra-low leakage (\\lt 10 pA), while also offering the high current densities needed for phase-change memory and the fully bipolar operation needed for high-performance RRAM. Scalability to critical lateral dimensions \\lt 30 nm and thicknesses \\lt 15 nm, tight distributions and 100% yield in large (512 kBit) arrays, long-term stability of the ultra-low leakage states, and sub-50 ns turn-ON times have all been demonstrated. Numerical modeling of these MIEC-based ADs shows that their operation depends on C{{u}+} mediated hole

  11. Laser-Assisted Simultaneous Transfer and Patterning of Vertically Aligned Carbon Nanotube Arrays on Polymer Substrates for Flexible Devices

    KAUST Repository

    In, Jung Bin

    2012-09-25

    We demonstrate a laser-assisted dry transfer technique for assembling patterns of vertically aligned carbon nanotube arrays on a flexible polymeric substrate. A laser beam is applied to the interface of a nanotube array and a polycarbonate sheet in contact with one another. The absorbed laser heat promotes nanotube adhesion to the polymer in the irradiated regions and enables selective pattern transfer. A combination of the thermal transfer mechanism with rapid direct writing capability of focused laser beam irradiation allows us to achieve simultaneous material transfer and direct micropatterning in a single processing step. Furthermore, we demonstrate that malleability of the nanotube arrays transferred onto a flexible substrate enables post-transfer tailoring of electric conductance by collapsing the aligned nanotubes in different directions. This work suggests that the laser-assisted transfer technique provides an efficient route to using vertically aligned nanotubes as conductive elements in flexible device applications. © 2012 American Chemical Society.

  12. Self-activated mesh device using shape memory alloy for periosteal expansion osteogenesis.

    Science.gov (United States)

    Yamauchi, Kensuke; Takahashi, Tetsu; Tanaka, Kenko; Nogami, Shinnosuke; Kaneuji, Takeshi; Kanetaka, Hiroyasu; Miyazaki, Toshiki; Lethaus, Bernd; Kessler, Peter

    2013-07-01

    The present study evaluated the use of this self-activated shape memory alloy (SMA) device, with a focus on its effects in the region under the periosteum. Twelve Japanese white rabbits were used in this study. The device was inserted under the periosteum at the forehead. In the experimental group, the device was pushed, bent, and attached to the bone surface and fixed with a titanium screw. In control group, the device was only inserted under the periosteum. After 14 days, the screw was removed and the mesh was activated in the experimental group. Rabbits were sacrificed 5 and 8 weeks after the operation and newly formed bone was histologically and radiographically evaluated. The quantitative data by the area and the occupation of newly formed bone indicated that the experimental group had a higher volume of new bone than the control group at each consolidation period. Histologically, some newly formed bone was observed and most of the subperiosteal space underneath the device was filled with fibrous tissue, and a thin layer of immature bone was observed in the control group. In the experimental group, multiple dome-shaped bones, outlined by thin and scattered trabeculae, were clearly observed under the SMA mesh device. The use of self-activated devices for the periosteal expansion technique may make it possible to avoid donor site morbidity, trans-skin activation rods, any bone-cutting procedure, and the following intermittent activation procedure.

  13. Exploring Spin-transfer-torque devices and memristors for logic and memory applications

    Science.gov (United States)

    Pajouhi, Zoha

    As scaling CMOS devices is approaching its physical limits, researchers have begun exploring newer devices and architectures to replace CMOS. Due to their non-volatility and high density, Spin Transfer Torque (STT) devices are among the most prominent candidates for logic and memory applications. In this research, we first considered a new logic style called All Spin Logic (ASL). Despite its advantages, ASL consumes a large amount of static power; thus, several optimizations can be performed to address this issue. We developed a systematic methodology to perform the optimizations to ensure stable operation of ASL. Second, we investigated reliable design of STT-MRAM bit-cells and addressed the conflicting read and write requirements, which results in overdesign of the bit-cells. Further, a Device/Circuit/Architecture co-design framework was developed to optimize the STT-MRAM devices by exploring the design space through jointly considering yield enhancement techniques at different levels of abstraction. Recent advancements in the development of memristive devices have opened new opportunities for hardware implementation of non-Boolean computing. To this end, the suitability of memristive devices for swarm intelligence algorithms has enabled researchers to solve a maze in hardware. In this research, we utilized swarm intelligence of memristive networks to perform image edge detection. First, we proposed a hardware-friendly algorithm for image edge detection based on ant colony. Next, we designed the image edge detection algorithm using memristive networks.

  14. Thin and flexible Ni-P based current collectors developed by electroless deposition for energy storage devices

    Science.gov (United States)

    Wu, Haoran; Susanto, Amelia; Lian, Keryn

    2017-02-01

    A PET film metalized by electroless nickel deposition was demonstrated as thin and flexible current collector for energy storage devices. The resultant nickel-on-PET film (Ni-PET) can be used both as current collector for electrochemical capacitors and as electrode for thin film batteries. The composition of Ni-PET was characterized by EDX and XPS. The electrochemical performance of the Ni-PET current collector was similar to Ni foil but with less hydrogen evolution at low potential. The Ni-PET film exhibited better flexibility than a metallic Ni foil. Carbon nanotubes were coated on a Ni-PET substrate to form an electrochemical capacitor electrode which exhibited high chemical stability in both liquid and solid electrolytes, showing strong promise for solid energy storage devices.

  15. ITO-free flexible polymer solar cells: From small model devices to roll-to-roll processed large modules

    DEFF Research Database (Denmark)

    Manceau, Matthieu; Angmo, Dechan; Jørgensen, Mikkel

    2011-01-01

    Manufacturing of flexible ITO-free polymer solar cell modules by roll-to-roll methods (R2R) is described. Inverted devices with top illumination were built on a Kapton foil and an Aluminum/Chromium bi-layer system was used as electron contact. The layer structure was Kapton/Al/Cr/P3HT:PCBM/PEDOT:......Manufacturing of flexible ITO-free polymer solar cell modules by roll-to-roll methods (R2R) is described. Inverted devices with top illumination were built on a Kapton foil and an Aluminum/Chromium bi-layer system was used as electron contact. The layer structure was Kapton/Al/Cr/P3HT...

  16. Charging effect in Au nanoparticle memory device with biomolecule binding mechanism.

    Science.gov (United States)

    Jung, Sung Mok; Kim, Hyung-Jun; Kim, Bong-Jin; Yoon, Tae-Sik; Kim, Yong-Sang; Lee, Hyun Ho

    2011-07-01

    Organic memory device having gold nanoparticle (Au NPs) has been introduced in the structure of metal-pentacene-insulator-silicon (MPIS) capacitor device, where the Au NPs layer was formed by a new bonding method. Biomolecule binding mechanism between streptavidin and biotin was used as a strong binding method for the formation of monolayered Au NPs on polymeric dielectric of poly vinyl alcohol (PVA). The self-assembled Au NPs was functioned to show storages of charge in the MPIS device. The binding by streptavidin and biotin was confirmed by AFM and UV-VIS. The UV-VIS absorption of the Au NPs was varied at 515 nm and 525 nm depending on the coating of streptavidin. The AFM image showed no formation of multi-stacked layers of the streptavidin-capped Au NPs on biotin-NHS layer. Capacitance-voltage (C-V) performance of the memory device was measured to investigate the charging effect from Au NPs. In addition, charge retention by the Au NPs storage was tested to show 10,000 s in the C-V curve.

  17. Thin and flexible solid-state organic ionic plastic crystal-polymer nanofibre composite electrolytes for device applications.

    Science.gov (United States)

    Howlett, Patrick C; Ponzio, Florian; Fang, Jian; Lin, Tong; Jin, Liyu; Iranipour, Nahid; Efthimiadis, Jim

    2013-09-07

    All solid-state organic ionic plastic crystal-polymer nanofibre composite electrolytes are described for the first time. The new composite materials exhibit enhanced conductivity, excellent thermal, mechanical and electrochemical stability and allow the production of optically transparent, free-standing, flexible, thin film electrolytes (10's μms thick) for application in electrochemical devices. Stable cycling of a lithium cell incorporating the new composite electrolyte is demonstrated, including cycling at lower temperatures than previously possible with the pure material.

  18. Flexible supercapacitors

    Institute of Scientific and Technical Information of China (English)

    Shan Shi; Chengjun Xu; Cheng Yang; Jia Li; Hongda Du; Baohua Li; Feiyu Kang

    2013-01-01

    Flexible supercapacitors show a great potential for applications in wearable,miniaturized,portable,largescale transparent and flexible consumer electronics due to their significant,inherent advantages,such as being flexible,lightweight,low cost and environmentally friendly in comparison with the current energy storage devices.In this report,recent progress on flexible supercapacitors,flexible electrodes and electrolytes is reviewed.In addition,the future challenges and opportunities are discussed.

  19. Growth and Characterization of Polyimide-Supported AlN Films for Flexible Surface Acoustic Wave Devices

    Science.gov (United States)

    Li, Qi; Liu, Hongyan; Li, Gen; Zeng, Fei; Pan, Feng; Luo, Jingting; Qian, Lirong

    2016-06-01

    Highly c-axis oriented aluminum nitride (AlN) films, which can be used in flexible surface acoustic wave (SAW) devices, were successfully deposited on polyimide (PI) substrates by direct current reactive magnetron sputtering without heating. The sputtering power, film thickness, and deposition pressure were optimized. The characterization studies show that at the optimized conditions, the deposited AlN films are composed of columnar grains, which penetrate through the entire film thickness (~2 μm) and exhibit an excellent (0002) texture with a full width at half maximum value of the rocking curve equal to 2.96°. The film surface is smooth with a root mean square value of roughness of 3.79 nm. SAW prototype devices with a center frequency of about 520 MHz and a phase velocity of Rayleigh wave of about 4160 m/s were successfully fabricated using the AlN/PI composite structure. The obtained results demonstrate that the highly c-axis oriented AlN films with a smooth surface and low stress can be produced on relatively rough, flexible substrates, and this composite structure can be possibly used in flexible SAW devices.

  20. Observation of nonvolatile resistive memory switching characteristics in Ag/graphene-oxide/Ag devices.

    Science.gov (United States)

    Venugopal, Gunasekaran; Kim, Sang-Jae

    2012-11-01

    In this paper, we report highly stable and bipolar resistive switching effects of Ag/Graphene oxide thinfilm/Ag devices. The graphene-oxide (GO) thinfilms were prepared on Ag/SiO2/Si substrates by spin-coating technique. The Ag/GO/Ag devices showed a steady and bipolar resistive switching characteristic. The resistance switching from low resistance state (LRS) and high resistance state (HRS) with the resistance ratio of HRS to LRS of about 10 which was attained at a voltage bias of 0.1 V. Based on the filamentary conduction model, the dominant conduction mechanism of switching effect was well explained. Our results show GO can be a promising candidate for future development of nonvolatile memory devices.

  1. Influence of heavy ion flux on single event effect testing in memory devices

    Science.gov (United States)

    Luo, Jie; Liu, Jie; Sun, Youmei; Hou, Mingdong; Xi, Kai; Liu, Tianqi; Wang, Bin; Ye, Bing

    2017-09-01

    The natural space presents a particle flux variable environment and choosing a suitable flux value for ground-based single event experiments is an unresolved problem so far. In this work, various types of memory devices have been tested over the ion flux range from 10 to 105 ions/(cm2·s) using different ions covering LET from 10.1 to 99.8 MeV·cm2/mg. It was found that for most devices the error rates of single event upsets are affected by the applied flux value. And the effect involving flux becomes prominent as it is increased above 103 ions/(cm2·s). Different devices behave differently as the flux is increased and the flux effect depends strongly on the LET of the impinging ions. The results concluded in this experiment are discussed in detail and recommendations for choosing appropriate experimental flux are given.

  2. Unusual magnetic behavior in a chiral-based magnetic memory device

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Dor, Oren; Yochelis, Shira [Department of Applied Physics, Center of Nanoscience and Nanotechnology, Hebrew University, Jerusalem 91904 (Israel); Felner, Israel, E-mail: Israel.felner@mail.huij.ac.il [“Racah” Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Paltiel, Yossi [Department of Applied Physics, Center of Nanoscience and Nanotechnology, Hebrew University, Jerusalem 91904 (Israel)

    2016-01-15

    In recent years chiral molecules were found to act as efficient spin filters. Using a multilayer structure with chiral molecules magnetic memory was realized. Observed rare magnetic phenomena in a chiral-based magnetic memory device was reported by O-Ben Dor et. al in Nature Commun, 4, 2256 (2013). This multi-layered device is built from α-helix L-polyalanine (AHPA-L) adsorbed on gold, Al{sub 2}O{sub 3} (7 nm) and Ni (30 nm) layers. It was shown that certain temperature range the FC branch crosses the magnetic peak (at 55 K) observed in the ZFC curve thus ZFC>FC. We show here that in another similar multi-layered material, at low applied field, the ZFC curve lies above the FC one up to 70 K. The two features have the same origin and the crucial necessary components to exhibit them are: AHPA-L and 30 nm Ni layered thick. Similar effects were also reported in sulfur doped amorphous carbon. A comparison between the two systems and the ingredients for these peculiar observations is discussed. - Highlights: • The highlights of the present manuscript is the peculiar magnetic behavior observed in a multilayer structure with chiral molecules, magnetic memory. • It is shown that certain temperature range the FC branch crosses the magnetic peak (at 55 K) observed in the ZFC curve thus ZFC>FC. • Similar effects were also reported in sulfur doped amorphous carbon.

  3. Synthesis of Gold Nanoparticles Capped with Quaterthiophene for Transistor and Resistor Memory Devices

    Directory of Open Access Journals (Sweden)

    Mai Ha Hoang

    2016-01-01

    Full Text Available Recently, the fabrication of nonvolatile memory devices based on gold nanoparticles has been intensively investigated. In this work, we report on the design and synthesis of new semiconducting quaterthiophene incorporating hexyl thiol group (4TT. Gold nanoparticles capped with 4TT (4TTG were prepared in a two-phase liquid-liquid system. These nanoparticles have diameters in the range 2–6 nm and are well dispersed in the poly(3-hexylthiophene (P3HT host matrix. The intermolecular interaction between 4TT and P3HT could enhance the charge-transport between gold nanoparticles and P3HT. Transfer curve of transistor memory device made of 4TTG/P3HT hybrid film exhibited significant current hysteresis, probably arising from the energy level barrier at 4TTG/P3HT interface. Additionally, the polymer memory resistor structure with an active layer consisting of 4TTG and P3HT displayed a remarkable electrical bistable behavior.

  4. Resistive switching memory based on bioinspired natural solid polymer electrolytes.

    Science.gov (United States)

    Raeis Hosseini, Niloufar; Lee, Jang-Sik

    2015-01-27

    A solution-processed, chitosan-based resistive-switching memory device is demonstrated with Pt/Ag-doped chitosan/Ag structure. The memory device shows reproducible and reliable bipolar resistive switching characteristics. A memory device based on natural organic material is a promising device toward the next generation of nonvolatile nanoelectronics. The memory device based on chitosan as a natural solid polymer electrolyte can be switched reproducibly between high and low resistance states. In addition, the data retention measurement confirmed the reliability of the chitosan-based nonvolatile memory device. The transparent Ag-embedded chitosan film showed an acceptable and comparable resistive switching behavior on the flexible plastic substrate as well. A cost-effective, environmentally benign memory device using chitosan satisfies the functional requirements of nonvolatile memory operations.

  5. Light-controlling, flexible and transparent ethanol gas sensor based on ZnO nanoparticles for wearable devices.

    Science.gov (United States)

    Zheng, Z Q; Yao, J D; Wang, B; Yang, G W

    2015-06-16

    In recent years, owing to the significant applications of health monitoring, wearable electronic devices such as smart watches, smart glass and wearable cameras have been growing rapidly. Gas sensor is an important part of wearable electronic devices for detecting pollutant, toxic, and combustible gases. However, in order to apply to wearable electronic devices, the gas sensor needs flexible, transparent, and working at room temperature, which are not available for traditional gas sensors. Here, we for the first time fabricate a light-controlling, flexible, transparent, and working at room-temperature ethanol gas sensor by using commercial ZnO nanoparticles. The fabricated sensor not only exhibits fast and excellent photoresponse, but also shows high sensing response to ethanol under UV irradiation. Meanwhile, its transmittance exceeds 62% in the visible spectral range, and the sensing performance keeps the same even bent it at a curvature angle of 90(o). Additionally, using commercial ZnO nanoparticles provides a facile and low-cost route to fabricate wearable electronic devices.

  6. Application of Multi-Objective Evolutionary Algorithm for Optimal Reactive Power Dispatch with Flexible AC Transmission System Devices

    Directory of Open Access Journals (Sweden)

    Abdarrazak OUALI

    2011-12-01

    Full Text Available Because their capability to change the network parameters with a rapid response and enhanced flexibility, flexible AC transmission system (FACTS devices have taken more attention in power systems operations as improvement of voltage profile and minimizing system losses. In this way, this paper presents a multi-objective evolutionary algorithm (MOEA to solve optimal reactive power dispatch (ORPD problem with FACTS devices. This nonlinear multi-objective problem (MOP consists to minimize simultaneously real power loss in transmission lines and voltage deviation at load buses, by tuning parameters and searching the location of FACTS devices. The constraints of this MOP are divided to equality constraints represented by load flow equations and inequality constraints such as, generation reactive power sources and security limits at load buses. Two types of FACTS devices, static synchronous series compensator (SSSC and unified power flow controller (UPFC are considered. A comparative study regarding the effects of an SSSC and an UPFC on voltage deviation and total transmission real losses is carried out. The design problem is tested on a 6-bus system.

  7. Flexible Screen Propellant Management Device for Near Term In-Space Demonstration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — While evaluating lunar ascent and descent stage propellant acquisition options in 2008 and 2009 for NASA GRC, IES conceived a novel, flexible screen propellant...

  8. Inductively heated shape memory polymer for the magnetic actuation of medical devices.

    Science.gov (United States)

    Buckley, Patrick R; McKinley, Gareth H; Wilson, Thomas S; Small, Ward; Benett, William J; Bearinger, Jane P; McElfresh, Michael W; Maitland, Duncan J

    2006-10-01

    Presently, there is interest in making medical devices such as expandable stents and intravascular microactuators from shape memory polymer (SMP). One of the key challenges in realizing SMP medical devices is the implementation of a safe and effective method of thermally actuating various device geometries in vivo. A novel scheme of actuation by Curie-thermoregulated inductive heating is presented. Prototype medical devices made from SMP loaded with nickel zinc ferrite ferromagnetic particles were actuated in air by applying an alternating magnetic field to induce heating. Dynamic mechanical thermal analysis was performed on both the particle-loaded and neat SMP materials to assess the impact of the ferrite particles on the mechanical properties of the samples. Calorimetry was used to quantify the rate of heat generation as a function of particle size and volumetric loading of ferrite particles in the SMP. These tests demonstrated the feasibility of SMP actuation by inductive heating. Rapid and uniform heating was achieved in complex device geometries and particle loading up to 10% volume content did not interfere with the shape recovery of the SMP.

  9. Inductively Heated Shape Memory Polymer for the Magnetic Actuation of Medical Devices

    Energy Technology Data Exchange (ETDEWEB)

    Buckley, P; Mckinley, G; Wilson, T; Small, W; Benett, W; Bearinger, J; McElfresh, M; Maitland, D

    2005-09-06

    Presently there is interest in making medical devices such as expandable stents and intravascular microactuators from shape memory polymer (SMP). One of the key challenges in realizing SMP medical devices is the implementation of a safe and effective method of thermally actuating various device geometries in vivo. A novel scheme of actuation by Curie-thermoregulated inductive heating is presented. Prototype medical devices made from SMP loaded with Nickel Zinc ferrite ferromagnetic particles were actuated in air by applying an alternating magnetic field to induce heating. Dynamic mechanical thermal analysis was performed on both the particle-loaded and neat SMP materials to assess the impact of the ferrite particles on the mechanical properties of the samples. Calorimetry was used to quantify the rate of heat generation as a function of particle size and volumetric loading of ferrite particles in the SMP. These tests demonstrated the feasibility of SMP actuation by inductive heating. Rapid and uniform heating was achieved in complex device geometries and particle loading up to 10% volume content did not interfere with the shape recovery of the SMP.

  10. Self-formed conductive nanofilaments in (Bi, Mn)Ox for ultralow-power memory devices

    KAUST Repository

    Kang, Chen Fang

    2015-04-01

    Resistive random access memory (RRAM) is one of the most promising candidates as a next generation nonvolatile memory (NVM), owing to its superior scalability, low power consumption and high speed. From the materials science point of view, to explore optimal RRAM materials is still essential for practical application. In this work, a new material (Bi, Mn)Ox (BMO) is investigated and several key performance characteristics of Pt/BMO/Pt structured device, including switching performance, retention and endurance, are examined in details. Furthermore, it has been confirmed by high-resolution transmission electron microscopy that the underlying switching mechanism is attributed to formation and disruption of metallic conducting nanofilaments (CNFs). More importantly, the power dissipation for each CNF is as low as 3.8/20fJ for set/reset process, and a realization of cross-bar structure memory cell is demonstrated to prove the downscaling ability of proposed RRAM. These distinctive properties have important implications for understanding switching mechanisms and implementing ultralow power-dissipation RRAM based on BMO. •Self-formed conductive nanofilaments in BMO show ultralow-power memory feature.•The feature of 10nm in diameter and an average 20-30nm spacing of CNFs suggests the compatibility with the current CMOS technologies.•Power dissipation for each CNF is as low as 3.8/20fJ for set/reset process•A realization of cross-bar structure memory cell is demonstrated to prove the downscaling ability of proposed RRAM. © 2015 Elsevier Ltd.

  11. CMOS Compatible Nonvolatile Memory Devices Based on SiO2/Cu/SiO2 Multilayer Films

    Institute of Scientific and Technical Information of China (English)

    WANG Yan; LIU Qi; LV Hang-Bing; LONG Shi-Bing; ZHANG Sen; LI Ying-Tao; LIAN Wen-Tai; YANG Jian-Hong; LIU Ming

    2011-01-01

    We systematically investigate the resistive switching characteristics of SiO2 films with a Cu/SiO2/Cu/SiO2/Pt multilayer structure. The device exhibits good resistive switching performances,including a high ON/OFF resistance ratio (>103),good retention characteristic (>104 s),satisfactory switching endurance (>200cycles),a fast programming speed (<100ns) and a high device yield (~100%).Considering these results,SiO2-based memories have highly promising applications for nonvolatile memory devices.

  12. Crawling is Associated with More Flexible Memory Retrieval by 9-Month-Old Infants

    Science.gov (United States)

    Herbert, Jane; Gross, Julien; Hayne, Harlene

    2007-01-01

    In the present experiment, we used a deferred imitation paradigm to explore the effect of crawling on memory retrieval by 9-month-old human infants. Infants observed an experimenter demonstrate a single target action with a novel object and their ability to reproduce that action was assessed after a 24-hr delay. Some infants were tested with the…

  13. Flexible Ablators

    Science.gov (United States)

    Stackpoole, Margaret M. (Inventor); Ghandehari, Ehson M. (Inventor); Thornton, Jeremy J. (Inventor); Covington, Melmoth Alan (Inventor)

    2017-01-01

    A low-density article comprising a flexible substrate and a pyrolizable material impregnated therein, methods of preparing, and devices using the article are disclosed. The pyrolizable material pyrolizes above 350 C and does not flow at temperatures below the pyrolysis temperature. The low-density article remains flexible after impregnation and continues to remain flexible when the pyrolizable material is fully pyrolized.

  14. Chemical insight into origin of forming-free resistive random-access memory devices

    KAUST Repository

    Wu, X.

    2011-09-29

    We demonstrate the realization of a forming-step free resistive random access memory (RRAM) device using a HfOx/TiOx/HfOx/TiOxmultilayer structure, as a replacement for the conventional HfOx-based single layer structure. High-resolution transmission electron microscopy (HRTEM), along with electron energy loss spectroscopy(EELS)analysis has been carried out to identify the distribution and the role played by Ti in the RRAM stack. Our results show that Ti out-diffusion into the HfOx layer is the chemical cause of forming-free behavior. Moreover, the capability of Ti to change its ionic state in HfOx eases the reduction-oxidation (redox) reaction, thus lead to the RRAM devices performance improvements.

  15. Direct observation of nanometer-scale Joule and Peltier effects in phase change memory devices

    Science.gov (United States)

    Grosse, Kyle L.; Xiong, Feng; Hong, Sungduk; King, William P.; Pop, Eric

    2013-05-01

    We measure power dissipation in phase change memory (PCM) devices by scanning Joule expansion microscopy (SJEM) with ˜50 nm spatial and 0.2 K temperature resolution. The temperature rise in the Ge2Sb2Te5 (GST) is dominated by Joule heating, but at the GST-TiW contacts it is a combination of Peltier and current crowding effects. Comparison of SJEM and electrical measurements with simulations of the PCM devices uncovers a thermopower of ˜350 μV K-1 and a contact resistance of ˜2.0 × 10-8 Ω m2 (to TiW) for 25 nm thick films of face centered-cubic crystalline GST. Knowledge of such nanometer-scale Joule, Peltier, and current crowding effects is essential for energy-efficient design of future PCM technology.

  16. High performance flexible top-emitting warm-white organic light-emitting devices and chromaticity shift mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Hongying; Deng, Lingling; Chen, Shufen, E-mail: iamsfchen@njupt.edu.cn, E-mail: wei-huang@njupt.edu.cn; Xu, Ying; Zhao, Xiaofei; Cheng, Fan [Key Laboratory for Organic Electronics and Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 210023 Nanjing (China); Huang, Wei, E-mail: iamsfchen@njupt.edu.cn, E-mail: wei-huang@njupt.edu.cn [Key Laboratory for Organic Electronics and Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 210023 Nanjing (China); Jiangsu-Singapore Joint Research Center for Organic/Bio- Electronics and Information Displays and Institute of Advanced Materials, Nanjing University of Technology, Nanjing 211816 (China)

    2014-04-15

    Flexible warm-white top-emitting organic light-emitting devices (TEOLEDs) are fabricated onto PET substrates with a simple semi-transparent cathode Sm/Ag and two-color phosphors respectively doped into a single host material TCTA. By adjusting the relative position of the orange-red EML sandwiched between the blue emitting layers, the optimized device exhibits the highest power/current efficiency of 8.07 lm/W and near 13 cd/A, with a correlated color temperature (CCT) of 4105 K and a color rendering index (CRI) of 70. In addition, a moderate chromaticity variation of (-0.025, +0.008) around warm white illumination coordinates (0.45, 0.44) is obtained over a large luminance range of 1000 to 10000 cd/m{sup 2}. The emission mechanism is discussed via delta-doping method and single-carrier device, which is summarized that the carrier trapping, the exciton quenching, the mobility change and the recombination zone alteration are negative to color stability while the energy transfer process and the blue/red/blue sandwiched structure are contributed to the color stability in our flexible white TEOLEDs.

  17. The effect of medical device dose-memory functions on patients’ adherence to treatment, confidence, and disease self-management

    Directory of Open Access Journals (Sweden)

    Hall RL

    2014-05-01

    Full Text Available Rebecca L Hall,1 Thomas Willgoss,1 Louise J Humphrey,1 Jens Harald Kongsø2 1Adelphi Values, Adelphi Mill, Bollington, Cheshire, UK; 2Novo Nordisk A/S, Novo Allé, Bagsværd, Denmark Background: Adherence to treatment is an important issue in chronic disease management and an indicator of patients’ ability to self-manage their condition and treatment. Some drug-dispensing and drug-delivery devices have been designed to support patients’ medication-taking behavior by including dose-memory and combined dose-memory and dose-reminder functions, which electronically store, and visually display dose-history information, enabling the patient to review, monitor, and/or be actively reminded about their medication doses.Purpose: This literature review explored the role and impact of these devices on patients’ treatment adherence, confidence with, and self-management of their condition and treatment.Materials and methods: A search of MEDLINE, Embase, and PsycINFO was performed to identify articles published in English from 2003–2013 that studied the effect of devices with dose-memory and combined dose-memory and dose-reminder functions on treatment adherence and users’ (patients, health care professionals [HCPs], and caregivers confidence, self-management behavior, and attitudes.Results: The database searches yielded 940 abstracts from which 13 articles met the inclusion criteria and were retained. Devices with dose-memory and combined dose-memory and dose-reminder functions were found to improve self-reported and electronically monitored treatment adherence in chronic conditions such as asthma, diabetes, and HIV. The ability of the devices to provide dose-history information and active medication reminders was considered valuable in disease management by patients, caregivers, and HCPs. The devices were found to enhance patients’ confidence in, and motivation to manage their medication and condition, and help reduce forgotten or incorrect

  18. Scalability of valence change memory: From devices to tip-induced filaments

    Directory of Open Access Journals (Sweden)

    U. Celano

    2016-08-01

    Full Text Available Since the early days of the investigation on resistive switching (RS, the independence of the ON-state resistance with actual cell area has been a trademark of filamentary-switching. However, with the continuous downscaling of the memory cell down to 10 x 10 nm2 and below, the persistence of this phenomena raises intriguing questions on the conductive filaments (CFs and its dimensions. Particularly, the cell functionality demonstrated at relatively high switching current (> 100 μA implies a high current density (> 106 A/cm2 inside a CF supposedly confined in few hundreds on nm3. We previously demonstrated a methodology for the direct observation of CFs in integrated devices namely scalpel SPM, which overcomes most of the characterization challenges imposed by the device structure and the small CF lateral dimensions. In this letter, we use scalpel SPM to clarify the scaling potential of HfO2-based valence change memory (VCM by characterization of CFs programmed at relatively high switching current and by AFM tip-induced RS experiments. Besides the demonstration of a remarkable scaling potential for the VCM technology, our results are also used to clarify the present understanding on the AFM-based experiments.

  19. Scalability of valence change memory: From devices to tip-induced filaments

    Science.gov (United States)

    Celano, U.; Fantini, A.; Degraeve, R.; Jurczak, M.; Goux, L.; Vandervorst, W.

    2016-08-01

    Since the early days of the investigation on resistive switching (RS), the independence of the ON-state resistance with actual cell area has been a trademark of filamentary-switching. However, with the continuous downscaling of the memory cell down to 10 x 10 nm2 and below, the persistence of this phenomena raises intriguing questions on the conductive filaments (CFs) and its dimensions. Particularly, the cell functionality demonstrated at relatively high switching current (> 100 μA) implies a high current density (> 106 A/cm2) inside a CF supposedly confined in few hundreds on nm3. We previously demonstrated a methodology for the direct observation of CFs in integrated devices namely scalpel SPM, which overcomes most of the characterization challenges imposed by the device structure and the small CF lateral dimensions. In this letter, we use scalpel SPM to clarify the scaling potential of HfO2-based valence change memory (VCM) by characterization of CFs programmed at relatively high switching current and by AFM tip-induced RS experiments. Besides the demonstration of a remarkable scaling potential for the VCM technology, our results are also used to clarify the present understanding on the AFM-based experiments.

  20. A flexible unified architecture to support heterogeneous multi-device learning environments

    NARCIS (Netherlands)

    Giemza, Adam; Bollen, Lars; Jansen, Marc; Ulrich Hoppe, H.

    2013-01-01

    Since the personal ownership of mobile devices has increased steadily over the last decade, many students own personal mobile devices that can reasonably be integrated into mobile learning scenarios. Besides all the benefits this option brings, there are also drawbacks, such as the heterogeneity of

  1. Ambient fabrication of flexible and large-area organic light-emitting devices using slot-die coating

    DEFF Research Database (Denmark)

    Sandstrom, Andreas; Dam, Henrik Friis; Krebs, Frederik C;

    2012-01-01

    The grand vision of manufacturing large-area emissive devices with low-cost roll-to-roll coating methods, akin to how newspapers are produced, appeared with the emergence of the organic light-emitting diode about 20 years ago. Today, small organic light-emitting diode displays are commercially...... available in smartphones, but the promise of a continuous ambient fabrication has unfortunately not materialized yet, as organic light-emitting diodes invariably depend on the use of one or more time-and energy-consuming process steps under vacuum. Here we report an all-solution-based fabrication...... of an alternative emissive device, a light-emitting electrochemical cell, using a slot-die roll-coating apparatus. The fabricated flexible sheets exhibit bidirectional and uniform light emission, and feature a fault-tolerant >1-mu m-thick active material that is doped in situ during operation. It is notable...

  2. Memory

    Science.gov (United States)

    ... it has to decide what is worth remembering. Memory is the process of storing and then remembering this information. There are different types of memory. Short-term memory stores information for a few ...

  3. Nonvolatile write-once-read-many times memory devices based on the composites of poly(4-vinylphenol)/Vulcan XC-72.

    Science.gov (United States)

    Song, Sunghoon; Kim, Tae-Wook; Cho, Byungjin; Ji, Yongsung; Lee, Takhee

    2011-05-01

    We fabricated write-once-read-many times (WORM) type organic memory devices in 8 x 8 cross-bar structure. The active material for organic based WORM memory devices is mixture of both poly(4-vinyphenol) (PVP) and Vulcan XC-72s. From the electrical characteristics of the WORM memory devices, we observed two different resistance states, low resistance state and high resistance state, with six orders of ON/OFF ratio (I(ON)/I(OFF) - 10(6)). In addition, the WORM memory devices were maintained for longer than 50000 seconds without any serious degradation.

  4. Controlling the Resistive Switching Behavior in Starch-Based Flexible Biomemristors.

    Science.gov (United States)

    Raeis-Hosseini, Niloufar; Lee, Jang-Sik

    2016-03-23

    Implementation of biocompatible materials in resistive switching memory (ReRAM) devices provides opportunities to use them in biomedical applications. We demonstrate a robust, nonvolatile, flexible, and transparent ReRAM based on potato starch. We also introduce a biomolecular memory device that has a starch-chitosan composite layer. The ReRAM behavior can be controlled by mixing starch with chitosan in the resistive switching layer. Whereas starch-based biomemory devices which show abrupt changes in current level; the memory device with mixed biopolymers undergoes gradual changes. Both devices exhibit uniform and robust programmable memory properties for nonvolatile memory applications. The explicated source of the bipolar resistive switching behavior is assigned to formation and rupture of carbon-rich filaments. The gradual set/reset behavior in the memory device based on a starch-chitosan mixture makes it suitable for use in neuromorphic devices.

  5. Direct X-ray photoconversion in flexible organic thin film devices operated below 1 V.

    Science.gov (United States)

    Basiricò, Laura; Ciavatti, Andrea; Cramer, Tobias; Cosseddu, Piero; Bonfiglio, Annalisa; Fraboni, Beatrice

    2016-10-06

    The application of organic electronic materials for the detection of ionizing radiations is very appealing thanks to their mechanical flexibility, low-cost and simple processing in comparison to their inorganic counterpart. In this work we investigate the direct X-ray photoconversion process in organic thin film photoconductors. The devices are realized by drop casting solution-processed bis-(triisopropylsilylethynyl)pentacene (TIPS-pentacene) onto flexible plastic substrates patterned with metal electrodes; they exhibit a strong sensitivity to X-rays despite the low X-ray photon absorption typical of low-Z organic materials. We propose a model, based on the accumulation of photogenerated charges and photoconductive gain, able to describe the magnitude as well as the dynamics of the X-ray-induced photocurrent. This finding allows us to fabricate and test a flexible 2 × 2 pixelated X-ray detector operating at 0.2 V, with gain and sensitivity up to 4.7 × 10(4) and 77,000 nC mGy(-1) cm(-3), respectively.

  6. Flexible robotic retrograde renoscopy: description of novel robotic device and preliminary laboratory experience.

    Science.gov (United States)

    Desai, Mihir M; Aron, Monish; Gill, Inderbir S; Pascal-Haber, Georges; Ukimura, Osamu; Kaouk, Jihad H; Stahler, Gregory; Barbagli, Federico; Carlson, Christopher; Moll, Fredric

    2008-07-01

    To describe a novel flexible robotic system for performing retrograde intrarenal surgery. Remote robotic flexible ureterorenoscopy was performed bilaterally in 5 acute swine (10 kidneys). A novel 14F robotic catheter system, which manipulated a passive optical fiberscope mounted on a remote catheter manipulator was used. The technical feasibility, efficiency, and reproducibility of accessing all calices were assessed. Additionally, laser lithotripsy of calculi and laser ablation of renal papillae were performed. The robotic catheter system could be introduced de novo in eight ureters; two ureters required balloon dilation. The ureteroscope could be successfully manipulated remotely into 83 (98%) of the 85 calices. The time required to inspect all calices within a given kidney decreased with experience from 15 minutes in the first kidney to 49 seconds in the last (mean 4.6 minutes). On a visual analog scale (1, worst to 10, best), the reproducibility of caliceal access was rated at 8, and instrument tip stability was rated at 10. A renal pelvic perforation constituted the solitary complication. Histologic examination of the ureter showed changes consistent with acute dilation without areas of necrosis. A novel robotic catheter system is described for performing retrograde ureterorenoscopy. The potential advantages compared with conventional manual flexible ureterorenoscopy include an increased range of motion, instrument stability, and improved ergonomics. Ongoing refinement is likely to expand the role of this technology in retrograde intrarenal surgery in the near future.

  7. Flexible unicast-based group communication for CoAP-enabled devices.

    Science.gov (United States)

    Ishaq, Isam; Hoebeke, Jeroen; Van den Abeele, Floris; Rossey, Jen; Moerman, Ingrid; Demeester, Piet

    2014-06-04

    Smart embedded objects will become an important part of what is called the Internet of Things. Applications often require concurrent interactions with several of these objects and their resources. Existing solutions have several limitations in terms of reliability, flexibility and manageability of such groups of objects. To overcome these limitations we propose an intermediately level of intelligence to easily manipulate a group of resources across multiple smart objects, building upon the Constrained Application Protocol (CoAP). We describe the design of our solution to create and manipulate a group of CoAP resources using a single client request. Furthermore we introduce the concept of profiles for the created groups. The use of profiles allows the client to specify in more detail how the group should behave. We have implemented our solution and demonstrate that it covers the complete group life-cycle, i.e., creation, validation, flexible usage and deletion. Finally, we quantitatively analyze the performance of our solution and compare it against multicast-based CoAP group communication. The results show that our solution improves reliability and flexibility with a trade-off in increased communication overhead.

  8. Flexible Unicast-Based Group Communication for CoAP-Enabled Devices

    Directory of Open Access Journals (Sweden)

    Isam Ishaq

    2014-06-01

    Full Text Available Smart embedded objects will become an important part of what is called the Internet of Things. Applications often require concurrent interactions with several of these objects and their resources. Existing solutions have several limitations in terms of reliability, flexibility and manageability of such groups of objects. To overcome these limitations we propose an intermediately level of intelligence to easily manipulate a group of resources across multiple smart objects, building upon the Constrained Application Protocol (CoAP. We describe the design of our solution to create and manipulate a group of CoAP resources using a single client request. Furthermore we introduce the concept of profiles for the created groups. The use of profiles allows the client to specify in more detail how the group should behave. We have implemented our solution and demonstrate that it covers the complete group life-cycle, i.e., creation, validation, flexible usage and deletion. Finally, we quantitatively analyze the performance of our solution and compare it against multicast-based CoAP group communication. The results show that our solution improves reliability and flexibility with a trade-off in increased communication overhead.

  9. Flexible Unicast-Based Group Communication for CoAP-Enabled Devices

    Science.gov (United States)

    Ishaq, Isam; Hoebeke, Jeroen; Van den Abeele, Floris; Rossey, Jen; Moerman, Ingrid; Demeester, Piet

    2014-01-01

    Smart embedded objects will become an important part of what is called the Internet of Things. Applications often require concurrent interactions with several of these objects and their resources. Existing solutions have several limitations in terms of reliability, flexibility and manageability of such groups of objects. To overcome these limitations we propose an intermediately level of intelligence to easily manipulate a group of resources across multiple smart objects, building upon the Constrained Application Protocol (CoAP). We describe the design of our solution to create and manipulate a group of CoAP resources using a single client request. Furthermore we introduce the concept of profiles for the created groups. The use of profiles allows the client to specify in more detail how the group should behave. We have implemented our solution and demonstrate that it covers the complete group life-cycle, i.e., creation, validation, flexible usage and deletion. Finally, we quantitatively analyze the performance of our solution and compare it against multicast-based CoAP group communication. The results show that our solution improves reliability and flexibility with a trade-off in increased communication overhead. PMID:24901978

  10. Flexible Electronics Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Flexible Electronics Research Facility designs, synthesizes, tests, and fabricates materials and devices compatible with flexible substrates for Army information...

  11. Fractional derivative and hereditary combined model for memory effects on flexible polyurethane foam

    Science.gov (United States)

    Elfarhani, Makram; Jarraya, Abdessalem; Abid, Said; Haddar, Mohamed

    2016-06-01

    In a quasi-static regime with cyclic loading, the force-displacement curve of flexible polyurethane exhibits complicated behavior: nonlinearity, visco-elasticity, hysteresis, residual force, etc. Beside nonlinearity and visco-elasticity, this material displays high dependence on the displacement rate and past loading history. Its dependence on compression rate helps to appropriately identify the force-displacement curve. Based on the new curve identification, the overall foam response is assumed to be a composite of a nonlinear elastic component and a visco-elastic component. The elastic component is expressed as a polynomial function in displacement, while the visco-elastic one is formulated according to the hereditary approach to represent the foam visco-elastic damping force during the loading phase and according to the fractional derivative approach during unloading to represent the visco-elastic residual force in the material. The focus of this study was to develop mathematical formulations and identification parameters to faithfully characterize the visco-elastic behavior of flexible polyurethane foam under multi-cycle compressive tests. A parameter calibration methodology based on the separation of the measurement data of each component force was established. This optimization process helps to avoid the parameter values admixture problem during the phase of numeric calculations of the same component force. The validity of the model results is checked according to the simulation accuracy, the physical significance of results and their agreement with the obtained force-displacement curve identification.

  12. Aluminum-Ion-Intercalation Supercapacitors with Ultrahigh Areal Capacitance and Highly Enhanced Cycling Stability: Power Supply for Flexible Electrochromic Devices.

    Science.gov (United States)

    Li, Kerui; Shao, Yuanlong; Liu, Shiyi; Zhang, Qinghong; Wang, Hongzhi; Li, Yaogang; Kaner, Richard B

    2017-05-01

    Electrochemical capacitor systems based on Al ions can offer the possibilities of low cost and high safety, together with a three-electron redox-mechanism-based high capacity, and thus are expected to provide a feasible solution to meet ever-increasing energy demands. Here, highly efficient Al-ion intercalation into W18 O49 nanowires (W18 O49 NWs) with wide lattice spacing and layered single-crystal structure for electrochemical storage is demonstrated. Moreover, a freestanding composite film with a hierarchical porous structure is prepared through vacuum-assisted filtration of a mixed dispersion containing W18 O49 NWs and single-walled carbon nanotubes. The as-prepared composite electrode exhibits extremely high areal capacitances of 1.11-2.92 F cm(-2) and 459 F cm(-3) at 2 mA cm(-2) , enhanced electrochemical stability in the Al(3+) electrolyte, as well as excellent mechanical properties. An Al-ion-based, flexible, asymmetric electrochemical capacitor is assembled that displays a high volumetric energy density of 19.0 mWh cm(-3) at a high power density of 295 mW cm(-3) . Finally, the Al-ion-based asymmetric supercapacitor is used as the power source for poly(3-hexylthiophene)-based electrochromic devices, demonstrating their promising capability in flexible electronic devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Effect of hydrogen ion beam treatment on Si nanocrystal/SiO{sub 2} superlattice-based memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Sheng-Wen; Chen, Hui-Ju; Wu, Hsuan-Ta; Chuang, Bing-Ru; Shih, Chuan-Feng, E-mail: cfshih@mail.ncku.edu.tw

    2016-03-30

    Graphical abstract: - Highlights: • Memory window and retention properties are improved employing HIBAS technique. • The O/Si ratio and radiative recombination are changed by HIBAS. • Memory properties are affected not only by Si NCs and O/Si ratio but also the RDCs. • The mechanism of hydrogen ion beam alters the memory properties is investigated. - Abstract: This study presents a novel route for synthesizing silicon-rich oxide (SRO)/SiO{sub 2} superlattice-based memory devices with an improved memory window and retention properties. The SiO{sub 2} and SRO superlattices are deposited by reactive sputtering. Specifically, the hydrogen ion beam is used to irradiate the SRO layer immediately after its deposition in the vacuum chamber. The use of the hydrogen ion beam was determined to increase oxygen content and the density of the Si nanocrystals. The memory window increased from 16 to 25.6 V, and the leakage current decreased significantly by two orders, to under ±20 V, for the hydrogen ion beam-prepared devices. This study investigates the mechanism into how hydrogen ion beam treatment alters SRO films and influences memory properties.

  14. GA-based optimum design of a shape memory alloy device for seismic response mitigation

    Science.gov (United States)

    Ozbulut, O. E.; Roschke, P. N.; Y Lin, P.; Loh, C. H.

    2010-06-01

    Damping systems discussed in this work are optimized so that a three-story steel frame structure and its shape memory alloy (SMA) bracing system minimize response metrics due to a custom-tailored earthquake excitation. Multiple-objective numerical optimization that simultaneously minimizes displacements and accelerations of the structure is carried out with a genetic algorithm (GA) in order to optimize SMA bracing elements within the structure. After design of an optimal SMA damping system is complete, full-scale experimental shake table tests are conducted on a large-scale steel frame that is equipped with the optimal SMA devices. A fuzzy inference system is developed from data collected during the testing to simulate the dynamic material response of the SMA bracing subcomponents. Finally, nonlinear analyses of a three-story braced frame are carried out to evaluate the performance of comparable SMA and commonly used steel braces under dynamic loading conditions and to assess the effectiveness of GA-optimized SMA bracing design as compared to alternative designs of SMA braces. It is shown that peak displacement of a structure can be reduced without causing significant acceleration response amplification through a judicious selection of physical characteristics of the SMA devices. Also, SMA devices provide a recentering mechanism for the structure to return to its original position after a seismic event.

  15. The effect of medical device dose-memory functions on patients' adherence to treatment, confidence, and disease self-management.

    Science.gov (United States)

    Hall, Rebecca L; Willgoss, Thomas; Humphrey, Louise J; Kongsø, Jens Harald

    2014-01-01

    Adherence to treatment is an important issue in chronic disease management and an indicator of patients' ability to self-manage their condition and treatment. Some drug-dispensing and drug-delivery devices have been designed to support patients' medication-taking behavior by including dose-memory and combined dose-memory and dose-reminder functions, which electronically store, and visually display dose-history information, enabling the patient to review, monitor, and/or be actively reminded about their medication doses. This literature review explored the role and impact of these devices on patients' treatment adherence, confidence with, and self-management of their condition and treatment. A search of MEDLINE, Embase, and PsycINFO was performed to identify articles published in English from 2003-2013 that studied the effect of devices with dose-memory and combined dose-memory and dose-reminder functions on treatment adherence and users' (patients, health care professionals [HCPs], and caregivers) confidence, self-management behavior, and attitudes. The database searches yielded 940 abstracts from which 13 articles met the inclusion criteria and were retained. Devices with dose-memory and combined dose-memory and dose-reminder functions were found to improve self-reported and electronically monitored treatment adherence in chronic conditions such as asthma, diabetes, and HIV. The ability of the devices to provide dose-history information and active medication reminders was considered valuable in disease management by patients, caregivers, and HCPs. The devices were found to enhance patients' confidence in, and motivation to manage their medication and condition, and help reduce forgotten or incorrect medication dosing. The incorporation of dose-memory and combined dose-memory and dose-reminder functions in drug-delivery devices can improve patients' adherence, confidence, and self-management behavior. They can target non-intentional barriers to adherence and can

  16. Flexible shape-memory scaffold for minimally invasive delivery of functional tissues

    Science.gov (United States)

    Montgomery, Miles; Ahadian, Samad; Davenport Huyer, Locke; Lo Rito, Mauro; Civitarese, Robert A.; Vanderlaan, Rachel D.; Wu, Jun; Reis, Lewis A.; Momen, Abdul; Akbari, Saeed; Pahnke, Aric; Li, Ren-Ke; Caldarone, Christopher A.; Radisic, Milica

    2017-10-01

    Despite great progress in engineering functional tissues for organ repair, including the heart, an invasive surgical approach is still required for their implantation. Here, we designed an elastic and microfabricated scaffold using a biodegradable polymer (poly(octamethylene maleate (anhydride) citrate)) for functional tissue delivery via injection. The scaffold’s shape memory was due to the microfabricated lattice design. Scaffolds and cardiac patches (1 cm × 1 cm) were delivered through an orifice as small as 1 mm, recovering their initial shape following injection without affecting cardiomyocyte viability and function. In a subcutaneous syngeneic rat model, injection of cardiac patches was equivalent to open surgery when comparing vascularization, macrophage recruitment and cell survival. The patches significantly improved cardiac function following myocardial infarction in a rat, compared with the untreated controls. Successful minimally invasive delivery of human cell-derived patches to the epicardium, aorta and liver in a large-animal (porcine) model was achieved.

  17. Diode-less bilayer oxide (WO(x)-NbO(x)) device for cross-point resistive memory applications.

    Science.gov (United States)

    Liu, Xinjun; Sadaf, Sharif Md; Son, Myungwoo; Shin, Jungho; Park, Jubong; Lee, Joonmyoung; Park, Sangsu; Hwang, Hyunsang

    2011-11-25

    The combination of a threshold switching device and a resistive switching (RS) device was proposed to suppress the undesired sneak current for the integration of bipolar RS cells in a cross-point array type memory. A simulation for this hybrid-type device shows that the matching of key parameters between switch element and memory element is an important issue. Based on the threshold switching oxides, a conceptual structure with a simple metal-oxide 1-oxide 2-metal stack was provided to accommodate the evolution trend. We show that electroformed W-NbO(x)-Pt devices can simultaneously exhibit both threshold switching and memory switching. A qualitative model was suggested to elucidate the unique properties in a W-NbO(x)-Pt stack, where threshold switching is associated with a localized metal-insulator transition in the NbO(x) bulk, and the bipolar RS derives from a redox at the tip of the localized filament at the WO(x)-NbO(x) interface. Such a simple metal-oxide-metal structure, with functionally separated bulk and interface effects, provides a fabrication advantage for future high-density cross-point memory devices.

  18. Comparison of Cobra perilaryngeal airway (CobraPLA TM with flexible laryngeal mask airway in terms of device stability and ventilation characteristics in pediatric ophthalmic surgery

    Directory of Open Access Journals (Sweden)

    Rani A Sunder

    2012-01-01

    Full Text Available Background: Supraglottic airway devices play an important role in ophthalmic surgery. The flexible laryngeal mask airway (LMA TM is generally the preferred airway device. However, there are no studies comparing it with the Cobra perilaryngeal airway (CobraPLA TM in pediatric ophthalmic procedures. Aims: To analyze the intraoperative device stability and ability to maintain normocarbia of CobraPLA TM and compare it to that with flexible LMA TM . Materials and Methods: Ninety children of American Society for Anesthesiologists physical status 1 and 2, aged 3-15 years scheduled for elective ophthalmic surgeries were randomly assigned to either the CobraPLA TM or the flexible LMA TM group. After placement of each airway device, oropharyngeal leak pressure (OLP was noted. Adequate seal of the devices was confirmed at an inspired pressure of 15 cm H 2 O and pressure-controlled ventilation was initiated. Device displacement was diagnosed if there was a change in capnograph waveform, audible or palpable gas leak, change in expired tidal volume to 6 kPa, or need to increase inspired pressure to >18 cm H 2 O to maintain normocarbia. Results: Demographic data, duration, and type of surgery in both the groups were similar. A higher incidence of intraoperative device displacement was noted with the CobraPLA TM in comparison to flexible LMA TM (P < 0.001. Incidence of displacement was higher in strabismus surgery (7/12. Insertion characteristics and ventilation parameters were comparable. The OLP was significantly higher in CobraPLA TM group (28 ± 6.8 cm H 2 O compared to the flexible LMA TM group (19.9 ± 4.5 cm H 2 O (P < 0.001. Higher surgeon dissatisfaction (65.9% was seen in the CobraPLA TM group. Conclusion: The high incidence of device displacement and surgeon dissatisfaction make CobraPLA TM a less favorable option than flexible LMA TM in ophthalmic surgery.

  19. Highly stable and flexible silver nanowire-graphene hybrid transparent conducting electrodes for emerging optoelectronic devices.

    Science.gov (United States)

    Lee, Donghwa; Lee, Hyungjin; Ahn, Yumi; Jeong, Youngjun; Lee, Dae-Young; Lee, Youngu

    2013-09-07

    A new AgNW-graphene hybrid transparent conducting electrode (TCE) was prepared by dry-transferring a chemical vapor deposition (CVD)-grown monolayer graphene onto a pristine AgNW TCE. The AgNW-graphene hybrid TCE exhibited excellent optical and electrical properties as well as mechanical flexibility. The AgNW-graphene hybrid TCE showed highly enhanced thermal oxidation and chemical stabilities because of the superior gas-barrier property of the graphene protection layer. Furthermore, the organic solar cells with the AgNW-graphene hybrid TCE showed excellent photovoltaic performance as well as superior long-term stability under ambient conditions.

  20. Patient-specific flexible and stretchable devices for cardiac diagnostics and therapy.

    Science.gov (United States)

    Gutbrod, Sarah R; Sulkin, Matthew S; Rogers, John A; Efimov, Igor R

    2014-08-01

    Advances in material science techniques and pioneering circuit designs have led to the development of electronic membranes that can form intimate contacts with biological tissues. In this review, we present the range of geometries, sensors, and actuators available for custom configurations of electronic membranes in cardiac applications. Additionally, we highlight the desirable mechanics achieved by such devices that allow the circuits and substrates to deform with the beating heart. These devices unlock opportunities to collect continuous data on the electrical, metabolic, and mechanical state of the heart as well as a platform on which to develop high definition therapeutics.

  1. A Flexible Web-Based Approach to Modeling Tandem Photocatalytic Devices

    DEFF Research Database (Denmark)

    Seger, Brian; Hansen, Ole; Vesborg, Peter Christian Kjærgaard

    2017-01-01

    There have been several works modeling the optimal band gaps for tandem photocatalytic water splitting devices under different assumptions. Due to the many parameters involved, it is impossible for the authors to consider every conceivable situation. In this work, we have developed a web-based mo......There have been several works modeling the optimal band gaps for tandem photocatalytic water splitting devices under different assumptions. Due to the many parameters involved, it is impossible for the authors to consider every conceivable situation. In this work, we have developed a web...... previous experimental photoelectrodes, and quantitatively relates their performance to what would typically be expected via modeling programs....

  2. 柔性有机非易失性场效应晶体管存储器的研究进展%Progress of flexible organic non-volatile memory field-effect transistors

    Institute of Scientific and Technical Information of China (English)

    柴玉华; 郭玉秀; 卞伟; 李雯; 杨涛; 仪明东; 范曲立; 解令海; 黄维

    2014-01-01

    柔性有机非易失性场效应晶体管存储器具有柔性、质轻、成本低、可低温及大面积加工等优点,在射频识别标签、柔性存储、柔性集成电路和大面积柔性显示等领域展现出巨大的应用前景。本文在介绍柔性有机非易失性场效应晶体管存储器的衬底材料、器件结构和性能参数的基础上,总结了柔性有机非易失性场效应晶体管存储器的分类,并讨论了机械应力和不同温度对柔性有机非易失性场效应晶体管存储器性能参数的影响,最后展望了柔性有机非易失性场效应晶体管存储器的应用前景以及所面临的挑战。%Flexible organic non-volatile memory field-effect transistors (ONVMFETs) are promising candidates in the field of flexible organic electronic devices, which can be used in flexible radio frequency tags, memories, integrated circuits and large-area displays, because of their remarkable advantages such as flexibility, lightweight, low cost and large-area organic electronics. On the basis of the introduction of the development of flexible ONVMFETs in terms of substrates, structures and characteristics, the classification of flexible ONVMFETs is summarized. Meanwhile, we discuss the effects of mechanical stress and temperature on the performance of flexible ONVMFET. Finally, some prospects as well as the challenges are pointed out.

  3. All-magnetic magnetoresistive random access memory based on four terminal mCell device

    Science.gov (United States)

    Bromberg, D. M.; Sumbul, H. E.; Zhu, J.-G.; Pileggi, L.

    2015-05-01

    Magnetoresistive random access memory (MRAM) is a promising candidate to enable fast, non-volatile storage on chip. In this paper, we present an MRAM design where each bitcell is comprised entirely of four-terminal magnetic devices ("mCells") with no CMOS access transistors. We show that this design can achieve significant energy and area savings compared to the standard one transistor-one magnetic tunnel junction (1T1MTJ) bitcell based design. We estimate a write energy of ≈5 fJ/bit based on bitline and wordline voltages that operate at less than 100 mV with projected area smaller than that possible with aggressively scaled 10 nm node FinFETs in the 1T1MTJ design.

  4. Wavelet analisys and HHG in nanorings Their applications in logic gates and memory mass devices

    CERN Document Server

    Cricchio, Dario

    2015-01-01

    We study the application of one nanoring driven by a laser field in different states of polarization in logic circuits. In particular we show that assigning boolean values to different state of the incident laser field and to the emitted signals, we can create logic gates such as OR, XOR and AND. We also show the possibility to make logic circuits such as half-adder and full-adder using one and two nanoring respectively. Using two nanorings we made the Toffoli gate. Finally we use the final angular momentum acquired by the electron to store information and hence show the possibility to use an array of nanorings as a mass memory device.

  5. Electrophysical Properties of Ge-Sb-Te Thin Films for Phase Change Memory Devices

    Science.gov (United States)

    Lazarenko, P. I.; Kozyukhin, S. A.; Sherchenkov, A. A.; Babich, A. V.; Timoshenkov, S. P.; Gromov, D. G.; Zabolotskaya, A. V.; Kozik, V. V.

    2017-01-01

    In this work, we studied temperature dependences of the resistivity and current-voltage characteristics of amorphous thin films based on the materials of a Ge-Sb-Te system of compositions GeSb4Te7 (GST147), GeSb2Te4 (GST124), and Ge2Sb2Te5 (GST225) applied in the phase change memory devices. The effect of changes in the composition of thin films on the crystallization temperature, resistivity of films in amorphous and crystalline states, and on the activation energy of conductivity is determined. It is found that the peculiarity of these materials is the mechanism of two-channel conductivity where the contribution to the conductivity is made by charge carriers excited into localized states in the band tails and by carriers of the delocalized states in the valence band.

  6. Poly (vinylidene fluoride-trifluoroethylene/barium titanate nanocomposite for ferroelectric nonvolatile memory devices

    Directory of Open Access Journals (Sweden)

    Uvais Valiyaneerilakkal

    2013-04-01

    Full Text Available The effect of barium titanate (BaTiO3 nanoparticles (particle size <100nm on the ferroelectric properties of poly (vinylidenefluoride-trifluoroethylene P(VDF-TrFE copolymer has been studied. Different concentrations of nanoparticles were added to P(VDF-TrFE using probe sonication, and uniform thin films were made. Polarisation - Electric field (P-E hysteresis analysis shows an increase in remnant polarization (Pr and decrease in coercive voltage (Vc. Piezo-response force microscopy analysis shows the switching capability of the polymer composite. The topography and surface roughness was studied using atomic force microscopy. It has been observed that this nanocomposite can be used for the fabrication of non-volatile ferroelectric memory devices.

  7. Computational Analysis of Advanced Shape-Memory Alloy Devices Through a Robust Modeling Framework

    Science.gov (United States)

    Scalet, Giulia; Conti, Michele; Auricchio, Ferdinando

    2017-06-01

    Shape-memory alloys (SMA) provide significant advantages in various industrial fields, but their manufacturing and commercialization are currently hindered. This is attributed mainly to the poor knowledge of material behavior and the lack of standards in its mechanical characterization. SMA products are usually developed by trial-and-error testing to address specific design requirements, thus increasing costs and time. The development of simulation tools offers a possible solution to assist engineers and designers and allows to better understand SMA transformation phenomena. Accordingly, the purpose of the present paper is to numerically analyze and predict the response of spring-like actuators and septal occluders, which are industrial components exploiting the shape-memory and pseudoelastic properties of SMAs, respectively. The methodology includes two main stages: the implementation of the three-dimensional phenomenological model known as Souza- Auricchio model and the finite element modeling of the device. A discussion about the steps of each stage, as parameter identification and model generalizations, is provided. Validation results are presented through a comparison with the results of a performed experimental campaign. The framework proves good prediction capabilities and allows to reduce the number of experimental tests in the future.

  8. Atmospheric pressure plasma jet-synthesized electrochromic organomolybdenum oxide thin films for flexible electrochromic devices

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yung-Sen, E-mail: yslin@fcu.edu.tw; Tsai, Tsung-Hsien; Tien, Shih-Wei

    2013-02-01

    An investigation is conducted into fast synthesis of electrochromic organomolybdenum oxide (MoO{sub x}C{sub y}) thin films onto 40 Ω/□ flexible polyethylene terephthalate/indium tin oxide substrates via atmospheric pressure plasma jet. A precursor [molybdenum carbonyl, Mo(CO){sub 6}] vapor, carried by argon gas, is injected into air plasma torch to synthesize MoO{sub x}C{sub y} films for offering extraordinary electrochromic performance. Only low driving voltages from − 1 V to 1 V are needed to offer reversible Li{sup +} ion intercalation and deintercalation in a 1 M LiClO{sub 4}-propylene carbonate electrolyte. Light modulation with transmittance variation of up to 61%, optical density change of 0.54 and coloration efficiency of 37.5 cm{sup 2}/C at a wavelength of 550 nm after 200 cycles of cyclic voltammetry switching measurements is achieved. - Highlights: ► Fast deposition of MoO{sub x}C{sub y} film by an atmospheric pressure plasma jet ► Organic–inorganic hybrid MoO{sub x}C{sub y} films synthesized ► Flexible and electrochromic MoO{sub x}C{sub y} films produced.

  9. Effects of drying temperature and ethanol concentration on bipolar switching characteristics of natural Aloe vera-based memory devices.

    Science.gov (United States)

    Lim, Zhe Xi; Cheong, Kuan Yew

    2015-10-28

    Extracted, formulated, and processed natural Aloe vera has been used as an active layer for memory applications. The functional memory device is realized by a bottom-up structure of ITO/Aloe vera/Al in which the Aloe vera is spin-coated after mixing with different concentrations of ethanol (0-80 wt%) and subsequently dried at different temperatures (50-120 °C). From the current density-voltage measurements, the device can exhibit a reproducible bipolar switching characteristic with pure Aloe vera dried at 50 °C. It is proposed that charges are transported across the Aloe vera layer via space-charge-limited conduction (SCLC), and clusters of interstitial space formed by the functional groups of acemannans and de-esterified pectins in the dried Aloe vera contribute to the memory effect. The formation of charge traps in the Aloe vera layer is dependent on the drying temperature. The drying temperature of a memory-switching Aloe vera layer can be extended to 120 °C with the addition of appropriate amounts of ethanol. The concept of using natural Aloe vera as an active material for memory applications has been demonstrated, and the read memory window, ON/OFF ratio, and retention time are approximately 5.0 V, 10(3), and >10(4) s, respectively.

  10. Random laser action from a natural flexible biomembrane-based device

    Science.gov (United States)

    Liu, Xiyun; Li, Tingshuai; Yi, Tao; Wang, Chuanke; Li, Jin; Xu, Min; Huang, Dengfeng; Liu, Shenye; Jiang, Shaoen; Ding, Yongkun

    2016-07-01

    Incoherent random lasing action in flexible eggshell membranes infiltrated with rhodamine 6G laser dyes is demonstrated. Laser radiation is achieved by exciting samples with 1-ns pulses at 526 nm. A threshold of 58 μJ/pulse is measured for the samples. The minimum threshold decreases to 35 μJ/pulse after the sample is coated with gold nanoparticles using a magnetron sputtering technique. The peaks of emission spectra are observed to redshift from 576 to 596 nm as dye concentration rises from 0.03 to 0.6 wt%. A linewidth of approximately 5 nm is obtained for most samples. This study is expected to offer a new way to induce lasing emission using biological microfibrils, and enriches basic knowledge of biophotonics.

  11. Photochemical approach to high-barrier films for the encapsulation of flexible laminary electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Prager, L., E-mail: lutz.prager@iom-leipzig.de [Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig (Germany); Helmstedt, U. [Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig (Germany); Herrnberger, H. [Solarion AG, Pereser Höhe 1, Breitscheidstraße 45, 04442 Zwenkau (Germany); Kahle, O. [Fraunhofer-Einrichtung für Polymermaterialien und Composite PYCO, Kantstraße 55, 14513 Teltow (Germany); Kita, F. [AZ Electronic Materials Germany GmbH, Rheingaustraße 190-196, 65203 Wiesbaden (Germany); Münch, M. [Solarion AG, Pereser Höhe 1, Breitscheidstraße 45, 04442 Zwenkau (Germany); Pender, A.; Prager, A.; Gerlach, J.W. [Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig (Germany); Stasiak, M. [Fraunhofer-Einrichtung für Polymermaterialien und Composite PYCO, Kantstraße 55, 14513 Teltow (Germany)

    2014-11-03

    Based on results of preceding research and development, thin gas barriers were made by wet application of perhydropolysilazane solution onto polymer films and its subsequent photo-initiated conversion to dense silica layers applying vacuum ultraviolet irradiation. Compared to the state of the art, these layers were sufficiently improved and characterized by spectroscopic methods, by scanning electron microscopy and by gas permeation measurements. Water vapor transmission rates (WVTR) below 10{sup −2} g m{sup −2} d{sup −1} were achieved. In this way, single barrier films were developed and produced on a pilot plant from roll to roll, 250 mm wide, at speeds up to 10 m min{sup −1}. Two films were laminated using adhesives curable with ultraviolet (UV) light and evaluated by peel tests, gas permeation measurement and climate testing. It could be shown that the described high-barrier laminates which exhibit WVTR ≈ 5 × 10{sup −4} g m{sup −2} d{sup −1}, determined by the calcium mirror method, are suitable for encapsulation of flexible thin-film photovoltaic modules. Durability of the encapsulated modules could be verified in several climate tests including damp-heat, thermo-cycle (heating, freezing, wetting) and UV exposures which are equivalent to more than 20 years of endurance at outdoor conditions in temperate climate. In the frame of further research and technical development it seems to be possible to design a cost efficient industrial scale process for the production of encapsulation films for photovoltaic applications. - Highlights: • Dense silica barrier layers were developed by a photochemical approach. • Polymer based barrier films were laminated yielding flexible high-barrier films. • Using these laminates photovoltaic test modules were encapsulated and tested. • A durability of more than 20 years at outdoor conditions could be proved.

  12. Flexible MISFET devices from transfer printed Si microwires and spray coating

    OpenAIRE

    Khan, Saleem; Lorenzelli, Leandro; Dahiya, Ravinder

    2016-01-01

    This paper presents two types of MISFETs (Metal Insulator Field Effect Transistors) devices fabricated from Si microwires through a new manufacturing route involving a combination of printing and microfabrication technologies. Si microwires, developed through standard photolithography and etching steps, are transferred from a SOI (silicon on insulator) wafer onto polyimide (PI) using stamp-assisted transfer printing. The MISFETs are then obtained by spray coating the dielectric layer and meta...

  13. Electrochromic properties and performance of NiOx films and their corresponding all-thin-film flexible devices preparedby reactive DC magnetron sputtering

    Science.gov (United States)

    Dong, Dongmei; Wang, Wenwen; Dong, Guobo; Zhang, Fan; He, Yingchun; Yu, Hang; Liu, Famin; Wang, Mei; Diao, Xungang

    2016-10-01

    Nickel oxide (NiOx) thin films were deposited by direct current magnetron sputtering technique onto flexible substrates with various oxygen (O2) partial pressures. The influence of O2 contents during deposition process on film structure, morphology, composition, optical and electrochromic (EC) characteristics of the films were investigated. The EC response for nonstoichiometric NiOx films shows a strong dependence on grain size variations and surface morphology. Finally, the multiple-layer stacks ITO/NiOx/Ta2O5:H/WO3/ITO were sequentially vacuum deposited over flexible polyethylene terephthalate plates based on the optimization of NiOx single layers. A large optical contrast up to 60% and a good durability are obtained for full device. To perform preliminary research on the mechanical properties within flexible devices, we introduced nontrivial changes to the interfacial properties by replacing the glass with flexible polymers. The effects were studied through static bending and the nano-scratch test.

  14. Suppression of thermoelectric Thomson effect in silicon microwires under large electrical bias and implications for phase-change memory devices

    Science.gov (United States)

    Bakan, Gokhan; Gokirmak, Ali; Silva, Helena

    2014-12-01

    We have observed how thermoelectric effects that result in asymmetric melting of silicon wires are suppressed for increasing electric current density (J). The experimental results are investigated using numerical modeling of the self-heating process, which elucidates the relative contributions of the asymmetric thermoelectric Thomson heat (˜J) and symmetric Joule heating (˜J2) that lead to symmetric heating for higher current levels. These results are applied in modeling of the self-heating process in phase-change memory devices. While, phase-change memory devices show a clearly preferred operation polarity due to thermoelectric effects, nearly symmetric operation can be achieved with higher amplitude and shorter current pulses, which can lead to design of improved polarity-invariant memory circuitry.

  15. Parallel database search and prime factorization with magnonic holographic memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Khitun, Alexander [Electrical and Computer Engineering Department, University of California - Riverside, Riverside, California 92521 (United States)

    2015-12-28

    In this work, we describe the capabilities of Magnonic Holographic Memory (MHM) for parallel database search and prime factorization. MHM is a type of holographic device, which utilizes spin waves for data transfer and processing. Its operation is based on the correlation between the phases and the amplitudes of the input spin waves and the output inductive voltage. The input of MHM is provided by the phased array of spin wave generating elements allowing the producing of phase patterns of an arbitrary form. The latter makes it possible to code logic states into the phases of propagating waves and exploit wave superposition for parallel data processing. We present the results of numerical modeling illustrating parallel database search and prime factorization. The results of numerical simulations on the database search are in agreement with the available experimental data. The use of classical wave interference may results in a significant speedup over the conventional digital logic circuits in special task data processing (e.g., √n in database search). Potentially, magnonic holographic devices can be implemented as complementary logic units to digital processors. Physical limitations and technological constrains of the spin wave approach are also discussed.

  16. Exercise prevents high-fat diet-induced impairment of flexible memory expression in the water maze and modulates adult hippocampal neurogenesis in mice.

    Science.gov (United States)

    Klein, C; Jonas, W; Iggena, D; Empl, L; Rivalan, M; Wiedmer, P; Spranger, J; Hellweg, R; Winter, Y; Steiner, B

    2016-05-01

    Obesity is currently one of the most serious threats to human health in the western civilization. A growing body of evidence suggests that obesity is associated with cognitive dysfunction. Physical exercise not only improves fitness but it has also been shown in human and animal studies to increase hippocampus-dependent learning and memory. High-fat diet (HFD)-induced obesity and physical exercise both modulate adult hippocampal neurogenesis. Adult neurogenesis has been demonstrated to play a role in hippocampus-dependent learning and memory, particularly flexible memory expression. Here, we investigated the effects of twelve weeks of HFD vs. control diet (CD) and voluntary physical activity (wheel running; -R) vs. inactivity (sedentary; -S) on hippocampal neurogenesis and spatial learning and flexible memory function in female C57Bl/6 mice assessed in the Morris water maze. HFD was initiated either in adolescent mice combined with long-term concurrent exercise (preventive approach) or in young adult mice with 14days of subsequent exercise (therapeutic approach). HFD resulted in impaired flexible memory expression only when initiated in adolescent (HFD-S) but not in young adult mice, which was successfully prevented by concurrent exercise (HFD-R). Histological analysis revealed a reduction of immature neurons in the hippocampus of the memory-impaired HFD-S mice of the preventive approach. Long-term physical exercise also led to accelerated spatial learning during the acquisition period, which was accompanied by increased numbers of newborn mature neurons (HFD-R and CD-R). Short-term exercise of 14days in the therapeutic group was not effective in improving spatial learning or memory. We show that (1) alterations in learning and flexible memory expression are accompanied by changes in the number of neuronal cells at different maturation stages; (2) these neuronal cells are in turn differently affected by HFD; (3) adolescent mice are specifically susceptible to the

  17. Photochemical solution processing of films of metastable phases for flexible devices: the β-Bi2O3 polymorph

    Science.gov (United States)

    Pérez-Mezcua, Dulce; Bretos, Iñigo; Jiménez, Ricardo; Ricote, Jesús; Jiménez-Rioboó, Rafael J.; da Silva, Cosmelina Gonçalves; Chateigner, Daniel; Fuentes-Cobas, Luis; Sirera, Rafael; Calzada, M. Lourdes

    2016-12-01

    The potential of UV-light for the photochemical synthesis and stabilization of non-equilibrium crystalline phases in thin films is demonstrated for the β-Bi2O3 polymorph. The pure β-Bi2O3 phase is thermodynamically stable at high temperature (450–667 °C), which limits its applications in devices. Here, a tailored UV-absorbing bismuth(III)-N-methyldiethanolamine complex is selected as an ideal precursor for this phase, in order to induce under UV-light the formation of a –Bi–O–Bi– continuous network in the deposited layers and the further conversion into the β-Bi2O3 polymorph at a temperature as low as 250 °C. The stabilization of the β-Bi2O3 films is confirmed by their conductivity behavior and a thorough characterization of their crystal structure. This is also supported by their remarkable photocatalytic activity. Besides, this processing method has allowed us for the first time the preparation of β-Bi2O3 films on flexible plastic substrates, which opens new opportunities for using these materials in potential applications not available until now (e.g., flexible photocatalytic reactors, self-cleaning surfaces or wearable antimicrobial fabrics). Therefore, photochemical solution deposition (PCSD) demonstrates to be not only an efficient approach for the low temperature processing of oxide films, but also an excellent alternative for the stabilization of metastable phases.

  18. PEDOT:PSS Nanofilms Fabricated by a Nonconventional Coating Method for Uses as Transparent Conducting Electrodes in Flexible Electrochromic Devices

    Directory of Open Access Journals (Sweden)

    Kanyanee Sanglee

    2017-01-01

    Full Text Available Nanofilms of a polymer mixer of two ionomers, poly 3,4-ethylenedioxythiophene:poly(styrene sulfonic acid (PEDOT:PSS, were used as conducting materials to develop transparent conducting electrodes. It was firstly found that convective deposition, a versatile and wide-area coating method, could be used for the coating and acid treatment of PEDOT:PSS films. Electrical conductivity of the PEDOT:PSS films was significantly enhanced up to 1814 S/cm by only one-time surface treatment by a mild acid solution (4 M methanesulfonic acid. This is because some PSS chains were removed out from the polymer mixer films without damage on the substrates. UV-vis-NIR spectroscopy, Raman spectroscopy, and cyclic voltammetry were used to characterize the acid-treated transparent conducting films. In this report, obtained transparent conducting PEDOT:PSS films on polyester substrates were used as flexible electrodes for fabrication of flexible electrochromic devices. Poly(3-hexylthiophene (P3HT was used as an active layer, which its color changed reversibly from transparent-light blue to purple with a small applied voltage (±3 V.

  19. 电容式柔性触控装置的研制%Development of flexible capacitive touch control device

    Institute of Scientific and Technical Information of China (English)

    蒋晶晶; 丁辛

    2013-01-01

    为克服现有柔性触控装置分辨率较低及结构复杂等问题,应用电容式触控原理,开发了一种以单层非织碳膜为感应材料的柔性触控装置.测试表明,直角电极长度为72 mm的触控装置在126 mm×72 mm的工作区域内,X方向的线性度为±4.40%,y方向的线性度为±4.39%;分辨率为251 dpi×243 dpi.为进一步讨论装置的触控精度,定义了偏移率.测试表明:偏移率在6%以上的感应点集中于工作区域边缘;增加电极长度有利于提高线性区域面积,但幅度不大.基于柔性与可携带性需求,选用点电极制作触控装置较优.%To overcome the problems such as low resolution and complicated structure that are associated with the existing touch control device,based on the capacitive touch principle a flexible touch control device is developed using a single-layer inductive non-woven carbon film as its touchpad.When a working area in the touch pad is set as 126 mm × 72 mm,with 72 mm side length of L-shape electrode,the test results show that the linearity of the touch control device in X and Y directions is ±4.40% and ±4.39%,respectively,and that the resolution reaches as high as 251 dpi × 243 dpi.For further discussion on the controlling accuracy of the device,the deviation rate is defined.The test results show that the control positions,of which the deviation rates are greater than 6%,are located near the edges of the working area.In addition,increasing the side length of the L-shape electrodes has positive but limited effects on the improvement of the linearity.Therefore,it would be preferable to use point electrodes for flexibility and wearablity.

  20. Incidence of sore throat in children following use of flexible laryngeal mask airways - impact of an introducer device.

    Science.gov (United States)

    William, Anthea; Chambers, Neil A; Erb, Thomas O; von Ungern-Sternberg, Britta S

    2010-09-01

    Insertion of a flexible laryngeal mask airway (FLMA) is more difficult and therefore might result in a higher risk for trauma to the upper airway. To facilitate the insertion of FLMA, the use of an introducer device (Portex Limited, Hythe, Kent, UK) was promoted. However, the impact of the use of this device on the occurrence of postoperative sore throat is unknown. Four hundred children (3-21 years) undergoing elective ambulatory surgery were consecutively included in this study. In 196 cases, the FLMA was inserted using an introducer device. The FLMA cuff was then inflated and the pressure adjusted to below 60 cmH(2)O (according to manufacturers guidelines) using a calibrated cuff manometer (Portex Limited). Three types of FLMA were available: FLMA classic, FLMA unique (both FLMA PacMed, Richmond, Victoria, Australia) and FLMA ProBreathe (Well Lead Medical Co Ltd., Hualong, Guangzhou, China). Prior to discharge, patients' pain was assessed using an age appropriate scale. Thirteen children (3.3%) developed sore throat, two (0.5%) sore neck and three (0.75%) sore jaw. Of those that developed sore throat, seven had a FLMA inserted with an introducer, six without an introducer. Using a laryngeal mask airways (LMA) with a polyvinyl chloride (PVC), surface was associated with a higher risk for sore throat compared with an LMA with a silicone surface (P = 0.0002). In this study with controlled low cuff pressures, the incidence of sore throat was low. The use of an introducer device did not affect the rate of sore throat.

  1. Flexible piezoelectric PMN-PT nanowire-based nanocomposite and device.

    Science.gov (United States)

    Xu, Shiyou; Yeh, Yao-wen; Poirier, Gerald; McAlpine, Michael C; Register, Richard A; Yao, Nan

    2013-06-12

    Piezoelectric nanocomposites represent a unique class of materials that synergize the advantageous features of polymers and piezoelectric nanostructures and have attracted extensive attention for the applications of energy harvesting and self-powered sensing recently. Currently, most of the piezoelectric nanocomposites were synthesized using piezoelectric nanostructures with relatively low piezoelectric constants, resulting in lower output currents and lower output voltages. Here, we report a synthesis of piezoelectric (1 - x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) nanowire-based nanocomposite with significantly improved performances for energy harvesting and self-powered sensing. With the high piezoelectric constant (d33) and the unique hierarchical structure of the PMN-PT nanowires, the PMN-PT nanowire-based nanocomposite demonstrated an output voltage up to 7.8 V and an output current up to 2.29 μA (current density of 4.58 μA/cm(2)); this output voltage is more than double that of other reported piezoelectric nanocomposites, and the output current is at least 6 times greater. The PMN-PT nanowire-based nanocomposite also showed a linear relationship of output voltage versus strain with a high sensitivity. The enhanced performance and the flexibility of the PMN-PT nanowire-based nanocomposite make it a promising building block for energy harvesting and self-powered sensing applications.

  2. Flexible CMOS low-noise amplifiers for beyond-3G wireless hand-held devices

    Science.gov (United States)

    Becerra-Alvarez, Edwin C.; Sandoval-Ibarra, Federico; de la Rosa, José M.

    2009-05-01

    This paper explores the use of reconfigurable Low-Noise Amplifiers (LNAs) for the implementation of CMOS Radio Frequency (RF) front-ends in the next generation of multi-standard wireless transceivers. Main circuit strategies reported so far for multi-standard LNAs are reviewed and a novel flexible LNA intended for Beyond-3G RF hand-held terminals is presented. The proposed LNA circuit consists of a two-stage topology that combines inductive-source degeneration with PMOS-varactor based tuning network and a programmable load to adapt its performance to different standard specifications without penalizing the circuit noise and with a reduced number of inductors as compared to previous reported reconfigurable LNAs. The circuit has been designed in a 90-nm CMOS technology to cope with the requirements of the GSM, WCDMA, Bluetooth and WLAN (IEEE 802.11b-g) standards. Simulation results, including technology and packaging parasitics, demonstrate correct operation of the circuit for all the standards under study, featuring NF13.3dB and IIP3>10.9dBm, over a 1.85GHz-2.4GHz band, with an adaptive power consumption between 17mW and 22mW from a 1-V supply voltage. Preliminary experimental measurements are included, showing a correct reconfiguration operation within the operation band.

  3. Flexible Low-Mass Devices and Mechanisms Actuated by Electroactive Polymers

    Science.gov (United States)

    Bar-Cohen, Y; Leary, S.; Shahinpoor, M.; Harrison, J. O.; Smith, J.

    1999-01-01

    Miniature, lightweight, miser actuators that operate similar to biological muscles can be used to develop robotic devices with unmatched capabilities to impact many technology areas. Electroactive polymers (EAP) offer the potential to producing such actuators and their main attractive feature is their ability to induce relatively large bending or longitudinal strain. Generally, these materials produce a relatively low force and the applications that can be considered at the current state of the art are relatively limited. This reported study is concentrating on the development of effective EAPs and the resultant enabling mechanisms employing their unique characteristics. Several EAP driven mechanisms, which emulate human hand, were developed including a gripper, manipulator arm and surface wiper. The manipulator arm was made of a composite rod with an EAP actuator consisting of a scrolled rope that is activated longitudinally by an electrostatic field. A gripper was made to serve as an end effector and it consisted of multiple bending EAP fingers for grabbing and holding such objects as rocks. An EAP surface wiper was developed to operate like a human finger and to demonstrate the potential to remove dust from optical and IR windows as well as solar cells. These EAP driven devices are taking advantage of the large actuation displacement of these materials but there is need for a significantly greater actuation force capability.

  4. Flexible hybrid circuit fully inkjet-printed: Surface mount devices assembled by silver nanoparticles-based inkjet ink

    Science.gov (United States)

    Arrese, J.; Vescio, G.; Xuriguera, E.; Medina-Rodriguez, B.; Cornet, A.; Cirera, A.

    2017-03-01

    Nowadays, inkjet-printed devices such as transistors are still unstable in air and have poor performances. Moreover, the present electronics applications require a high degree of reliability and quality of their properties. In order to accomplish these application requirements, hybrid electronics is fulfilled by combining the advantages of the printing technologies with the surface-mount technology. In this work, silver nanoparticle-based inkjet ink (AgNP ink) is used as a novel approach to connect surface-mount devices (SMDs) onto inkjet-printed pads, conducted by inkjet printing technology. Excellent quality AgNP ink-junctions are ensured with high resolution picoliter drop jetting at low temperature (˜150 °C). Electrical, mechanical, and morphological characterizations are carried out to assess the performance of the AgNP ink junction. Moreover, AgNP ink is compared with common benchmark materials (i.e., silver epoxy and solder). Electrical contact resistance characterization shows a similar performance between the AgNP ink and the usual ones. Mechanical characterization shows comparable shear strength for AgNP ink and silver epoxy, and both present higher adhesion than solder. Morphological inspections by field-emission scanning electron microscopy confirm a high quality interface of the silver nanoparticle interconnection. Finally, a flexible hybrid circuit on paper controlled by an Arduino board is manufactured, demonstrating the viability and scalability of the AgNP ink assembling technique.

  5. Ventricle wall dissection and vascular preservation with the pulsed water jet device: novel tissue dissector for flexible neuroendoscopic surgery.

    Science.gov (United States)

    Kawaguchi, Tomohiro; Nakagawa, Atsuhiro; Endo, Toshiki; Fujimura, Miki; Sonoda, Yukihiko; Tominaga, Teiji

    2016-03-01

    Neuroendoscopic surgery allows minimally invasive surgery, but lacks effective methods to control bleeding. Water jet dissection with continuous flow has been used in liver and kidney surgery since the 1980s, and is effective for tissue manipulation with vascular preservation, but involves some potential risks, such as elevation of intracranial pressure during application in the ventricles. The authors previously reported the efficacy of the actuator-driven pulsed water jet device (ADPJ) to dissect soft tissue with vascular preservation in microscopic neurosurgery. This feasibility study investigated the use of the ADPJ to reduce the amount of water usage, leading to more safety with sustained efficacy. A small-diameter pulsed water jet device was developed for use with the flexible neuroendoscope. To identify the optimal conditions for the water jet, the flow rate, water pressure, and distance between the nozzle and target were analyzed in an in vitro study by using a gelatin brain phantom. A ventricle model was used to monitor the internal pressure and temperature. For ex vivo experiments the porcine brain was harvested and ventricle walls were exposed, and subsequently immersed into physiological saline. For in vivo experiments the cortex was microsurgically resected to make the small cortico-ventricle window, and then the endoscope was introduced to dissect ventricle walls. In the in vitro experiments, water pressure was approximately 6.5 bar at 0.5 mm from the ADPJ nozzle and was maintained at 1 mm, but dropped rapidly toward 50% at 2 mm, and became 10% at 3.5 mm. The ADPJ required less water to achieve the same dissection depth compared with the continuous-flow water jet. With the ventricle model, the internal pressure and temperature were well controlled at the baseline, with open water drainage. These results indicated that the ADPJ can be safely applied within the ventricles. The ADPJ was introduced into a flexible endoscope and the ventricle walls were

  6. Scalable printed electronics: an organic decoder addressing ferroelectric non-volatile memory

    National Research Council Canada - National Science Library

    Ng, Tse Nga; Schwartz, David E; Lavery, Leah L; Whiting, Gregory L; Russo, Beverly; Krusor, Brent; Veres, Janos; Bröms, Per; Herlogsson, Lars; Alam, Naveed; Hagel, Olle; Nilsson, Jakob; Karlsson, Christer

    2012-01-01

    .... The decoder-memory array is patterned by inkjet and gravure printing on flexible plastics. Simulation models for the organic transistors are developed, enabling circuit designs tolerant of the variations in printed devices...

  7. Nonvolatile Resistance Random Access Memory Devices Based on ZnO Nanorod Arrays

    Directory of Open Access Journals (Sweden)

    Liang-Wen Ji

    2015-02-01

    Full Text Available In this paper, a nonvolatile resistance random access memory (RRAM device based on ZnO nanorod arrays has been fabricated and characterized. Vertically aligned ZnO nanorod layers (NRLs were deposited on indium tin oxide (ITO electrodes using a hydrothermal process/ chemical bath deposition (CBD. It can be found the Ag/ZnO NRL/ITO capacitor exhibits bipolar resistive switching behavior. The resistive switching behavior may be related to the oxygen vacancies and/or zinc interstitials confined on the surface of the ZnO NRs, giving rise to the formation of straight and extensible conducting path along each ZnO NR. Furthermore, superior stability in resistive switching characteristics was also observed. Both growing times and annealing times were investigated and annealing was done in oxygen for 3, 6 and 9 minutes at different temperatures. For ZnO nanorods that had been annealed for 6 minutes the forming voltage was about 6.06V, the Set voltage was about 3.25V and the Reset voltage was -2.78V. The original resistance was 7×106Ω. The resistance in the low-resistance state was 108Ω and in the high-resistance state was 2016Ω, the resistance ratio was 18.7.

  8. Treatment of ingrown nail with a special device composed of shape-memory alloy.

    Science.gov (United States)

    Park, Se-Won; Park, Ji-Ho; Lee, Jong-Hee; Lee, Dong-Youn; Lee, Joo-Heung; Yang, Jun-Mo

    2014-04-01

    Ingrown nail is a common nail problem resulting in pain and disability in daily life. Recently, a new treatment modality for an ingrown nail was reported that used a device composed of shape-memory alloy, K-D. The aim of the present study was to determine the efficacy, recurrence rate and complications of K-D. Between June 2010 and September 2012, 24 patients (31 nails) underwent treatment of symptomatic incurved nails with a K-D. Patients were evaluated at pretreatment and during every visit. The mean age of the patients involved was 43.4 years. The mean period of follow up was 161 days. The mean maintenance period was 41 days. The right first toenail was the most common site. Almost ingrown nails healed and the nail deformity was corrected after the procedure. Among the 31 nails, seven of the ingrown nails recurred during follow up (22.6% recurrence rate). The recurrence rate of the patients with stage 1, 2 and 3 ingrown nails was 22.2%, 33.3% and 14.2%, respectively. The majority of patients were very satisfied. There were no side-effects in most patients except loss of nail in one patient. K-D has some advantages such as simple application steps, no deformity after the procedure, high patient satisfaction and obvious effect compared to other non-invasive and invasive methods. © 2014 Japanese Dermatological Association.

  9. Nanoscale design of multifunctional organic layers for low-power high-density memory devices.

    Science.gov (United States)

    Nougaret, Laurianne; Kassa, Hailu G; Cai, Ronggang; Patois, Tilia; Nysten, Bernard; van Breemen, Albert J J M; Gelinck, Gerwin H; de Leeuw, Dago M; Marrani, Alessio; Hu, Zhijun; Jonas, Alain M

    2014-04-22

    We demonstrate the design of a multifunctional organic layer by the rational combination of nanosized regions of two functional polymers. Instead of relying on a spontaneous and random phase separation process or on the tedious synthesis of block copolymers, the method involves the nanomolding of a first component, followed by the filling of the resulting open spaces by a second component. We apply this methodology to fabricate organic nonvolatile memory diodes of high density. These are built by first creating a regular array of ferroelectric nanodots by nanoimprint lithography, followed by the filling of the trenches separating the ferroelectric nanodots with a semiconducting polymer. The modulation of the current in the semiconductor by the polarization state of the ferroelectric material is demonstrated both at the scale of a single semiconductor channel and in a microscopic device measuring about 80,000 channels in parallel, for voltages below ca. 2 V. The fabrication process, which combines synergetically orthogonal functional properties with a fine control over their spatial distribution, is thus demonstrated to be efficient over large areas.

  10. Can conventional phase-change memory devices be scaled down to single-nanometre dimensions?

    Science.gov (United States)

    Hayat, Hasan; Kohary, Krisztian; Wright, C. David

    2017-01-01

    The scaling potential of ‘mushroom-type’ phase-change memory devices is evaluated, down to single-nanometre dimensions, using physically realistic simulations that combine electro-thermal modelling with a Gillespie Cellular Automata phase-transformation approach. We found that cells with heater contact sizes as small as 6 nm could be successfully amorphized and re-crystallized (RESET and SET) using moderate excitation voltages. However, to enable the efficient formation of amorphous domes during RESET in small cells (heater contact diameters of 10 nm or less), it was necessary to improve the thermal confinement of the cell to reduce heat loss via the electrodes. The resistance window between the SET and RESET states decreased as the cell size reduced, but it was still more than an order of magnitude even for the smallest cells. As expected, the RESET current reduced as the cells got smaller; indeed, RESET current scaled with the inverse of the heater contact diameter and ultra-small RESET currents of only 19 μA were achieved for the smallest cells. Our results show that the conventional mushroom-type phase-change cell architecture is scalable and operable in the sub-10nm region.

  11. Comparative study of CNT, silicon nanowire and fullerene embedded multilayer high-k gate dielectric MOS memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Sengupta, Amretashis; Sarkar, Chandan Kumar [Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata-700 032 (India); Requejo, Felix G, E-mail: amretashis@gmail.com [INIFTA, Departmento de Quimica and Departmento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC/67-1900, La Plata (Argentina)

    2011-10-12

    Here, we present a comparative theoretical study on stacked (multilayer) gate dielectric MOS memory devices, having a metallic/semiconducting carbon nanotube (CNT), silicon nanowire (Si NW) and fullerene (C60) embedded nitride layer acting as a floating gate. Two types of devices, one with HfO{sub 2}-SiO{sub 2} stack (stack-1) and the other with La{sub 2}O{sub 3}-SiO{sub 2} stack (stack-2) as the tunnel oxide were compared. We evaluated the effective barrier height, the dielectric constant and the effective electron mobility in the composite gate dielectric with the Maxwell-Garnett effective medium theory. Thereafter applying the WKB approximation, we simulated the Fowler-Nordheim (F-N) tunnelling/writing current and the direct tunnelling/leakage current in these devices. We evaluated the I-V characteristics, the charge decay and also the impact of CNT/Si NW aspect ratio and the volume fraction on the effective barrier height and the write voltage, respectively. We also simulated the write time, retention time and the erase time of these MOS devices. Based on the simulation results, it was concluded that the metallic CNT embedded stack-1 device offered the best performance in terms of higher F-N tunnelling current, lower direct tunnelling current and lesser write voltage and write time compared with the other devices. In case of direct tunnelling leakage and retention time it was found that the met CNT embedded stack-2 device showed better characteristics. For erasing, however, the C60 embedded stack-1 device showed the smallest erase time. When compared with earlier reports, it was seen that CNT, C60 and Si NW embedded devices all performed better than nanocrystalline Si embedded MOS non-volatile memories.

  12. Toward Wearable Cooling Devices: Highly Flexible Electrocaloric Ba0.67 Sr0.33 TiO3 Nanowire Arrays.

    Science.gov (United States)

    Zhang, Guangzu; Zhang, Xiaoshan; Huang, Houbing; Wang, Jianjun; Li, Qi; Chen, Long-Qing; Wang, Qing

    2016-06-01

    Flexible lead-free ferroelectric ceramic nanowire arrays exhibit a unique combination of features that can contribute to the realization of wearable cooling devices, including an outstanding electrocaloric effect at low fields, high efficiency, bendability and stretchability, and robustness against mechanical deformations. Thermodynamic and phase-field simulations are carried out to validate their superior electrocaloric effect in comparison to thin films.

  13. Management of long-term and reversible hysteroscopic sterilization: a novel device with nickel-titanium shape memory alloy.

    Science.gov (United States)

    Xu, Bin; Zhu, Ke-an; Xu, Dabao; Aili, Aixingzi

    2014-07-07

    Female sterilization is the second most commonly used method of contraception in the United States. Female sterilization can now be performed through laparoscopic, abdominal, or hysteroscopic approaches. The hysteroscopic sterilization may be a safer option than sterilization through laparoscopy or laparotomy because it avoids invading the abdominal cavity and undergoing general anaesthesia. Hysteroscopic sterilization mainly includes chemical agents and mechanical devices. Common issues related to the toxicity of the chemical agents used have raised concerns regarding this kind of contraception. The difficulty of the transcervical insertion of such mechanical devices into the fallopian tubes has increased the high incidence of device displacement or dislodgment. At present, Essure® is the only commercially available hysteroscopic sterilization device being used clinically. The system is irreversible and is not effective immediately. Our new hysteroscopic sterility system consists of nickel-titanium (NiTi) shape memory alloy and a waterproof membrane. The NiTi alloy is covered with two coatings to avoid toxic Ni release and to prevent stimulation of epithelial tissue growth around the oviducts. Because of the shape memory effect of the NiTi alloy, the device works like an umbrella: it stays collapsed at low temperature before placement and opens by the force of shape memory activated by the body temperature after it is inserted hysteroscopically into the interstitial tubal lumen. The rim of the open device will incise into interstitial myometrium during the process of unfolding. Once the device is fixed, it blocks the tube completely. When the patient no longer wishes for sterilization, the device can be closed by perfusing liquid with low temperature into the uterine cavity, followed by prospective hysteroscopic removal. After the device removal, the fallopian tube will revert to its physiological functions. Currently, experimental and clinical studies are needed

  14. Electrical bistabilities and operating mechanisms of memory devices fabricated utilizing ZnO quantum dot-multi-walled carbon nanotube nanocomposites

    Science.gov (United States)

    Li, Fushan; Son, Dong Ick; Cho, Sung Hwan; Kim, Tae Whan

    2009-05-01

    Transmission electron microscopy images showed that the ZnO quantum dots (QDs) were conjugated with multi-walled carbon nanotubes (MWCNTs). Bistable memories utilizing an ensemble of the ZnO QD-MWCNT heterostructures were developed and the storage capability of the devices was significantly enhanced due to the conjugation of the ZnO QDs and the MWCNTs. Operating mechanisms of memory devices fabricated utilizing the ZnO QD-MWCNT heterostructures are described on the basis of the current-voltage results. The memory devices exhibited excellent environmental stability at ambient conditions.

  15. Modeling for Formation of Conducting Path in Cu/SiO2/Pt Memory Devices: Based on Soft Breakdown Mechanism

    Science.gov (United States)

    Luo, J. M.

    2013-09-01

    The forming process before resistive switching in Cu/ SiO2/Pt memory devices, corresponding to the formation of conducting path, can be regarded as the dielectric soft breakdown. Based on the analysis of breakdown mechanism, a dynamic model combining the transition of Cu ions with the space-charge effect has been proposed, and demonstrates that the forming voltage depends on the thickness of oxide, the sweep rate of voltage and temperature. The predictions of the model are consistent with the experiment data reported in the literature and it is believed that the transition of Cu ions across the oxide and the accumulation of Cu ions at the SiO2/Pt interface could be responsible for the conductive path formation in Cu/SiO2/Pt memory devices.

  16. Flexible ferroelectric element based on van der Waals heteroepitaxy.

    Science.gov (United States)

    Jiang, Jie; Bitla, Yugandhar; Huang, Chun-Wei; Do, Thi Hien; Liu, Heng-Jui; Hsieh, Ying-Hui; Ma, Chun-Hao; Jang, Chi-Yuan; Lai, Yu-Hong; Chiu, Po-Wen; Wu, Wen-Wei; Chen, Yi-Chun; Zhou, Yi-Chun; Chu, Ying-Hao

    2017-06-01

    We present a promising technology for nonvolatile flexible electronic devices: A direct fabrication of epitaxial lead zirconium titanate (PZT) on flexible mica substrate via van der Waals epitaxy. These single-crystalline flexible ferroelectric PZT films not only retain their performance, reliability, and thermal stability comparable to those on rigid counterparts in tests of nonvolatile memory elements but also exhibit remarkable mechanical properties with robust operation in bent states (bending radii down to 2.5 mm) and cycling tests (1000 times). This study marks the technological advancement toward realizing much-awaited flexible yet single-crystalline nonvolatile electronic devices for the design and development of flexible, lightweight, and next-generation smart devices with potential applications in electronics, robotics, automotive, health care, industrial, and military systems.

  17. Endurance degradation and lifetime model of p-channel floating gate flash memory device with 2T structure

    Science.gov (United States)

    Wei, Jiaxing; Liu, Siyang; Liu, Xiaoqiang; Sun, Weifeng; Liu, Yuwei; Liu, Xiaohong; Hou, Bo

    2017-08-01

    The endurance degradation mechanisms of p-channel floating gate flash memory device with two-transistor (2T) structure are investigated in detail in this work. With the help of charge pumping (CP) measurements and Sentaurus TCAD simulations, the damages in the drain overlap region along the tunnel oxide interface caused by band-to-band (BTB) tunneling programming and the damages in the channel region resulted from Fowler-Nordheim (FN) tunneling erasure are verified respectively. Furthermore, the lifetime model of endurance characteristic is extracted, which can extrapolate the endurance degradation tendency and predict the lifetime of the device.

  18. The effect of the thickness of tunneling layer on the memory properties of (Cu2O)0.5(Al2O3)0.5 high-k composite charge-trapping memory devices

    Science.gov (United States)

    Liu, Jinqiu; Lu, Jianxin; Yin, Jiang; Xu, Bo; Xia, Yidong; Liu, Zhiguo

    2016-06-01

    The charge-trapping memory devices namely Pt/Al2O3/(Al2O3)0.5(Cu2O)0.5/SiO2/p-Si with 2, 3 and 4 nm SiO2 tunneling layers were fabricated by using RF magnetron sputtering and atomic layer deposition techniques. At an applied voltage of ±11 V, the memory windows in the C-V curves of the memory devices with 2, 3 and 4 nm SiO2 tunneling layers were about 4.18, 9.91 and 11.33 V, respectively. The anomaly in memory properties among the three memory devices was ascribed to the different back tunneling probabilities of trapped electrons in the charge-trapping dielectric (Al2O3)0.5(Cu2O)0.5 due to the different thicknesses of SiO2 tunneling layer.

  19. Electric field mediated non-volatile tuning magnetism in CoPt/PMN-PT heterostructure for magnetoelectric memory devices

    Science.gov (United States)

    Yang, Y. T.; Li, J.; Peng, X. L.; Wang, X. Q.; Wang, D. H.; Cao, Q. Q.; Du, Y. W.

    2016-02-01

    We report a power efficient non-volatile magnetoelectric memory in the CoPt/(011)PMN-PT heterostructure. Two reversible and stable electric field induced coercivity states (i.e., high-HC or low-HC) are obtained due to the strain mediated converse magnetoelectric effect. The reading process of the different coercive field information written by electric fields is demonstrated by using a magnetoresistance read head. This result shows good prospects in the application of novel multiferroic devices.

  20. Matrix-dependent Strain Distributions of Au and Ag Nanoparticles in a Metal-oxide-semiconductor-based Nonvolatile Memory Device

    OpenAIRE

    Honghua Huang; Ying Zhang; Wenyan Wei; Ting Yu; Xingfang Luo; Cailei Yuan

    2015-01-01

    The matrix-dependent strain distributions of Au and Ag nanoparticles in a metal-oxide-semiconductor based nonvolatile memory device are investigated by finite element calculations. The simulation results clearly indicate that both Au and Ag nanoparticles incur compressive strain by high-k Al2O3 and conventional SiO2 dielectrics. The strain distribution of nanoparticles is closely related to the surrounding matrix. Nanoparticles embedded in different matrices experience different compressive s...

  1. Metal induced crystallized poly-Si-based conductive bridge resistive switching memory device with one transistor and one resistor architecture

    Science.gov (United States)

    Chand, Umesh; Huang, Chun-Yang; Kumar, Dayanand; Tseng, Tseung-Yuen

    2015-11-01

    In this letter, the metal induced crystallization (MIC) process is used in the Si-based conductive bridging resistive random access memory (CBRAM) application. The amorphous Si (a-Si) is transformed to crystallized poly-silicon (poly-Si) at a low temperature by using Ni metal for inducing poly-Si to provide the resistive switching. The MIC process can produce a highly preferred orientation poly-Si film, which can create the exact paths or grain boundaries through the top and down electrodes in the present CBRAM device. The grain boundary in MIC poly-Si layer can confine the conductive filament of metal bridging growth in it, which can improve the switching fluctuation behavior in the nonvolatile memory application. Compared with the a-Si based device, a significant improvement in terms of resistive switching parameters such as stability and resistance distribution is demonstrated in the MIC poly-Si CBRAM device. Moreover, the well-behaved memory performance, such as high ON/OFF resistance ratio (4 order), a large AC endurance (106), and good retention characteristics (104 s at 125 °C) are achieved in the Cu/poly-Si/n+-Si CMOS compatible cross bar structure.

  2. Ag/Au/Polypyrrole Core-shell Nanowire Network for Transparent, Stretchable and Flexible Supercapacitor in Wearable Energy Devices

    Science.gov (United States)

    Moon, Hyunjin; Lee, Habeom; Kwon, Jinhyeong; Suh, Young Duk; Kim, Dong Kwan; Ha, Inho; Yeo, Junyeob; Hong, Sukjoon; Ko, Seung Hwan

    2017-02-01

    Transparent and stretchable energy storage devices have attracted significant interest due to their potential to be applied to biocompatible and wearable electronics. Supercapacitors that use the reversible faradaic redox reaction of conducting polymer have a higher specific capacitance as compared with electrical double-layer capacitors. Typically, the conducting polymer electrode is fabricated through direct electropolymerization on the current collector. However, no research have been conducted on metal nanowires as current collectors for the direct electropolymerization, even though the metal nanowire network structure has proven to be superior as a transparent, flexible, and stretchable electrode platform because the conducting polymer’s redox potential for polymerization is higher than that of widely studied metal nanowires such as silver and copper. In this study, we demonstrated a highly transparent and stretchable supercapacitor by developing Ag/Au/Polypyrrole core-shell nanowire networks as electrode by coating the surface of Ag NWs with a thin layer of gold, which provide higher redox potential than the electropolymerizable monomer. The Ag/Au/Polypyrrole core-shell nanowire networks demonstrated superior mechanical stability under various mechanical bending and stretching. In addition, proposed supercapacitors showed fine optical transmittance together with fivefold improved areal capacitance compared to pristine Ag/Au core-shell nanowire mesh-based supercapacitors.

  3. Microfluidic Device to Measure the Speed of C. elegans Using the Resistance Change of the Flexible Electrode

    Directory of Open Access Journals (Sweden)

    Jaehoon Jung

    2016-03-01

    Full Text Available This work presents a novel method to assess the condition of Caenorhabditis elegans (C. elegans through a resistance measurement of its undulatory locomotion speed inside a micro channel. As the worm moves over the electrode inside the micro channel, the length of the electrode changes, consequently behaving like a strain gauge. In this paper, the electrotaxis was applied for controlling the direction of motion of C. elegans as an external stimulus, resulting in the worm moving towards the cathode of the circuit. To confirm the proposed measurement method, a microfluidic device was developed that employs a sinusoidal channel and a thin polydimethylsiloxane (PDMS layer with an electrode. The PDMS layer maintains a porous structure to enable the flexibility of the electrode. In this study, 6 measurements were performed to obtain the speed of an early adult stage C. elegans, where the measured average speed was 0.35 (±0.05 mm/s. The results of this work demonstrate the application of our method to measure the speed of C. elegans undulatory locomotion. This novel approach can be applied to make such measurements without an imaging system, and more importantly, allows directly to detect the locomotion of C. elegans using an electrical signal (i.e., the change in resistance.

  4. Ag/Au/Polypyrrole Core-shell Nanowire Network for Transparent, Stretchable and Flexible Supercapacitor in Wearable Energy Devices

    Science.gov (United States)

    Moon, Hyunjin; Lee, Habeom; Kwon, Jinhyeong; Suh, Young Duk; Kim, Dong Kwan; Ha, Inho; Yeo, Junyeob; Hong, Sukjoon; Ko, Seung Hwan

    2017-01-01

    Transparent and stretchable energy storage devices have attracted significant interest due to their potential to be applied to biocompatible and wearable electronics. Supercapacitors that use the reversible faradaic redox reaction of conducting polymer have a higher specific capacitance as compared with electrical double-layer capacitors. Typically, the conducting polymer electrode is fabricated through direct electropolymerization on the current collector. However, no research have been conducted on metal nanowires as current collectors for the direct electropolymerization, even though the metal nanowire network structure has proven to be superior as a transparent, flexible, and stretchable electrode platform because the conducting polymer’s redox potential for polymerization is higher than that of widely studied metal nanowires such as silver and copper. In this study, we demonstrated a highly transparent and stretchable supercapacitor by developing Ag/Au/Polypyrrole core-shell nanowire networks as electrode by coating the surface of Ag NWs with a thin layer of gold, which provide higher redox potential than the electropolymerizable monomer. The Ag/Au/Polypyrrole core-shell nanowire networks demonstrated superior mechanical stability under various mechanical bending and stretching. In addition, proposed supercapacitors showed fine optical transmittance together with fivefold improved areal capacitance compared to pristine Ag/Au core-shell nanowire mesh-based supercapacitors. PMID:28155913

  5. Highly flexible nearest-neighbor-search associative memory with integrated k nearest neighbor classifier, configurable parallelism and dual-storage space

    Science.gov (United States)

    An, Fengwei; Mihara, Keisuke; Yamasaki, Shogo; Chen, Lei; Jürgen Mattausch, Hans

    2016-04-01

    VLSI-implementations are often applied to solve the high computational cost of pattern matching but have usually low flexibility for satisfying different target applications. In this paper, a digital word-parallel associative memory architecture for k nearest neighbor (KNN) search, which is one of the most basic algorithms in pattern recognition, is reported applying the squared Euclidean distance measure. The reported architecture features reconfigurable parallelism, dual-storage space to achieve a flexible number of reference vectors, and a dedicated majority vote circuit. Programmable switching circuits, located between vector components, enable scalability of the searching parallelism by configuring the reference feature-vector dimensionality. A pipelined storage with dual static-random-access-memory (SRAM) cells for each unit and an intermediate winner control circuit are designed to extend the applicability by improving the flexibility of the reference storage. A test chip in 180 nm CMOS technology, which has 32 rows, 4 elements in each row and 2-parallel 8-bit dual-components in each element, consumes altogether 61.4 mW and in particular only 11.9 mW during the reconfigurable KNN classification (at 45.58 MHz and 1.8 V).

  6. Towards developing a compact model for magnetization switching in straintronics magnetic random access memory devices

    Science.gov (United States)

    Barangi, Mahmood; Erementchouk, Mikhail; Mazumder, Pinaki

    2016-08-01

    Strain-mediated magnetization switching in a magnetic tunneling junction (MTJ) by exploiting a combination of piezoelectricity and magnetostriction has been proposed as an energy efficient alternative to spin transfer torque (STT) and field induced magnetization switching methods in MTJ-based magnetic random access memories (MRAM). Theoretical studies have shown the inherent advantages of strain-assisted switching, and the dynamic response of the magnetization has been modeled using the Landau-Lifshitz-Gilbert (LLG) equation. However, an attempt to use LLG for simulating dynamics of individual elements in large-scale simulations of multi-megabyte straintronics MRAM leads to extremely time-consuming calculations. Hence, a compact analytical solution, predicting the flipping delay of the magnetization vector in the nanomagnet under stress, combined with a liberal approximation of the LLG dynamics in the straintronics MTJ, can lead to a simplified model of the device suited for fast large-scale simulations of multi-megabyte straintronics MRAMs. In this work, a tensor-based approach is developed to study the dynamic behavior of the stressed nanomagnet. First, using the developed method, the effect of stress on the switching behavior of the magnetization is investigated to realize the margins between the underdamped and overdamped regimes. The latter helps the designer realize the oscillatory behavior of the magnetization when settling along the minor axis, and the dependency of oscillations on the stress level and the damping factor. Next, a theoretical model to predict the flipping delay of the magnetization vector is developed and tested against LLG-based numerical simulations to confirm the accuracy of findings. Lastly, the obtained delay is incorporated into the approximate solutions of the LLG dynamics, in order to create a compact model to liberally and quickly simulate the magnetization dynamics of the MTJ under stress. Using the developed delay equation, the

  7. Towards developing a compact model for magnetization switching in straintronics magnetic random access memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Barangi, Mahmood, E-mail: barangi@umich.edu; Erementchouk, Mikhail; Mazumder, Pinaki [Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109-2121 (United States)

    2016-08-21

    Strain-mediated magnetization switching in a magnetic tunneling junction (MTJ) by exploiting a combination of piezoelectricity and magnetostriction has been proposed as an energy efficient alternative to spin transfer torque (STT) and field induced magnetization switching methods in MTJ-based magnetic random access memories (MRAM). Theoretical studies have shown the inherent advantages of strain-assisted switching, and the dynamic response of the magnetization has been modeled using the Landau-Lifshitz-Gilbert (LLG) equation. However, an attempt to use LLG for simulating dynamics of individual elements in large-scale simulations of multi-megabyte straintronics MRAM leads to extremely time-consuming calculations. Hence, a compact analytical solution, predicting the flipping delay of the magnetization vector in the nanomagnet under stress, combined with a liberal approximation of the LLG dynamics in the straintronics MTJ, can lead to a simplified model of the device suited for fast large-scale simulations of multi-megabyte straintronics MRAMs. In this work, a tensor-based approach is developed to study the dynamic behavior of the stressed nanomagnet. First, using the developed method, the effect of stress on the switching behavior of the magnetization is investigated to realize the margins between the underdamped and overdamped regimes. The latter helps the designer realize the oscillatory behavior of the magnetization when settling along the minor axis, and the dependency of oscillations on the stress level and the damping factor. Next, a theoretical model to predict the flipping delay of the magnetization vector is developed and tested against LLG-based numerical simulations to confirm the accuracy of findings. Lastly, the obtained delay is incorporated into the approximate solutions of the LLG dynamics, in order to create a compact model to liberally and quickly simulate the magnetization dynamics of the MTJ under stress. Using the developed delay equation, the

  8. Development of a novel shape memory alloy-actuated resettable locking device for magnetic bearing reaction wheel.

    Science.gov (United States)

    Zhang, Xiaoyong; Yan, Xiaojun; Zhang, Shaowei; Nie, Jingxu

    2014-01-01

    The current investigation proposes a shape memory alloy (SMA)-actuated resettable locking device for magnetic bearing reaction wheel. The device employed two SMA wire-based actuators to realize locking and unlocking. Dual-slope mating surfaces were used on one hand to transmit the motion between a moving part and a clamp, and on the other hand to achieve a self-locking linkage in the locking state. Moreover, geometric parameters of the two SMA wires and corresponding bias springs were also designed. Based on the proposed design scheme, four locking devices were manufactured and assembled. Performance and environmental tests were performed to verify the proposed locking device. Test results show that the locking device can protect the magnetic bearing reaction wheel from launch vibration damage, and can withstand the thermal environment in the launch and on-orbit stage. Moreover, the device can be successfully operated for 76 times, and the response time for the locking and unlocking processes under 7 V power supply is 0.9 s and 5.6 s, respectively. Considering the results obtained from these tests, we conclude that the proposed resettable locking device is an attractive alternative technology to conventional motor-driven or pyrotechnics-based technologies, and can be applied reliably in the magnetic bearing reaction wheel.

  9. Atomic-scale quantification of interdiffusion and dopant localization in GeSbTe-based memory devices

    Science.gov (United States)

    Chae, B.-G.; Seol, J.-B.; Song, J.-H.; Jung, W.-Y.; Hwang, H.; Park, C.-G.

    2016-09-01

    Fabrication of phase-change memory devices at modest or ambient temperatures leads to nanoscale compositional variations in phase-transition layers, where amorphous-polycrystalline phase change takes place via electrical switching, and can alter the device's performances. Here, by transmission electron microscopy and atom probe tomography, we address that thermal annealing at 400 °C for 20 min induces an elemental interdiffusion in the devices consisting of TiN (top electrode), carbon-doped GeSbTe (phase-transition layer), and TiSiN (bottom heater). With respect to the employed annealing process, the Ge atoms of GeSbTe layer have diffused into TiSiN layer at a given sample volume, while the Ti atoms of TiSiN layer into GeSbTe layer. Furthermore, non-random nature of dopant distribution in the GeSbTe materials leads to a Ti-localization including dopants at the GeSbTe/TiSiN interfaces. Our findings have two important implications: First, the annealing-driven interdiffusion of Ge and Ti is a predominant mechanism responsible for nanoscale compositional variations in GeSbTe layer; second, such an interdiffusion and the resultant dopant localization play a crucial role on the driving force for amorphous-polycrystalline transition of GeSbTe-based memory devices.

  10. Versatile Transfer of an Ultralong and Seamless Nanowire Array Crystallized at High Temperature for Use in High-Performance Flexible Devices.

    Science.gov (United States)

    Seo, Min-Ho; Yoo, Jae-Young; Choi, So-Young; Lee, Jae-Shin; Choi, Kwang-Wook; Jeong, Chang Kyu; Lee, Keon Jae; Yoon, Jun-Bo

    2017-02-28

    Nanowire (NW) transfer technology has provided promising strategies to realize future flexible materials and electronics. Using this technology, geometrically controlled, high-quality NW arrays can now be obtained easily on various flexible substrates with high throughput. However, it is still challenging to extend this technology to a wide range of high-performance device applications because its limited temperature tolerance precludes the use of high-temperature annealing, which is essential for NW crystallization and functionalization. A pulsed laser technique has been developed to anneal NWs in the presence of a flexible substrate; however, the induced temperature is not high enough to improve the properties of materials such as ceramics and semiconductors. Here, we present a versatile nanotransfer method that is applicable to NWs that require high-temperature annealing. To successfully anneal NWs during their transfer, the developed fabrication method involves sequential removal of a nanoscale sacrificial layer. Using this method, we first produce an ultralong, perfectly aligned polycrystalline barium titanate (BaTiO3) NW array that is heat treated at 700 °C on a flexible polyethylene terephthalate (PET) substrate. This high-quality piezoelectric NW array on a flexible substrate is used as a flexible nanogenerator that generates current and voltage 37 and 10 times higher, respectively, than those of a nanogenerator made of noncrystallized BaTiO3 NWs.

  11. SEMICONDUCTOR DEVICES Novel multi-bit non-uniform channel charge trapping memory device with virtual-source NAND flash array

    Science.gov (United States)

    Haiming, Gu; Liyang, Pan; Peng, Zhu; Dong, Wu; Zhigang, Zhang; Jun, Xu

    2010-10-01

    In order to overcome the bit-to-bit interference of the traditional multi-level NAND type device, this paper firstly proposes a novel multi-bit non-uniform channel charge trapping memory (NUC-CTM) device with virtual-source NAND-type array architecture, which can effectively restrain the second-bit effect (SBE) and provide 3-bit per cell capability. Owing to the n- buffer region, the SBE induced threshold voltage window shift can be reduced to less than 400 mV and the minimum threshold voltage window between neighboring levels is larger than 750 mV for reliable 3-bit operation. A silicon-rich SiON is also investigated as a trapping layer to improve the retention reliability of the NUC-CTM.

  12. Nanometer-scale temperature imaging for independent observation of Joule and Peltier effects in phase change memory devices.

    Science.gov (United States)

    Grosse, Kyle L; Pop, Eric; King, William P

    2014-09-01

    This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 μV K(-1). This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.

  13. Nanometer-scale temperature imaging for independent observation of Joule and Peltier effects in phase change memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Grosse, Kyle L. [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Pop, Eric [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); King, William P., E-mail: wpk@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Departments of Electrical and Computer Engineering and Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    2014-09-15

    This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 μV K{sup −1}. This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.

  14. Nanometer-scale temperature imaging for independent observation of Joule and Peltier effects in phase change memory devices

    Science.gov (United States)

    Grosse, Kyle L.; Pop, Eric; King, William P.

    2014-09-01

    This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 μV K-1. This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.

  15. Stretchable Organic Semiconductor Devices.

    Science.gov (United States)

    Qian, Yan; Zhang, Xinwen; Xie, Linghai; Qi, Dianpeng; Chandran, Bevita K; Chen, Xiaodong; Huang, Wei

    2016-11-01

    Stretchable electronics are essential for the development of intensely packed collapsible and portable electronics, wearable electronics, epidermal and bioimplanted electronics, 3D surface compliable devices, bionics, prosthesis, and robotics. However, most stretchable devices are currently based on inorganic electronics, whose high cost of fabrication and limited processing area make it difficult to produce inexpensive, large-area devices. Therefore, organic stretchable electronics are highly attractive due to many advantages over their inorganic counterparts, such as their light weight, flexibility, low cost and large-area solution-processing, the reproducible semiconductor resources, and the easy tuning of their properties via molecular tailoring. Among them, stretchable organic semiconductor devices have become a hot and fast-growing research field, in which great advances have been made in recent years. These fantastic advances are summarized here, focusing on stretchable organic field-effect transistors, light-emitting devices, solar cells, and memory devices.

  16. Nonvolatile memory devices based on ZnO/polyimide nanocomposite sandwiched between two C{sub 60} layers

    Energy Technology Data Exchange (ETDEWEB)

    Li Fushan [Advanced Semiconductor Research Center, Division of Electronics and Computer Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Tae Whan, E-mail: twk@hanyang.ac.k [Advanced Semiconductor Research Center, Division of Electronics and Computer Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Dong Wenguo; Kim, Young-Ho [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2009-05-29

    The memory effects of a three-layer nonvolatile memory device Al/C{sub 60}/ZnO nanoparticles embedded in a polyimide (PI) layer/C{sub 60}/p-Si were investigated by using capacitance-voltage (C-V) measurements. Transmission electron microscopy and selected area electron diffraction pattern measurements showed that ZnO nanocrystals were formed inside the PI layer. The insertion of C{sub 60} layer improved the charge trap state density in the ZnO nanoparticle. The density was estimated by the flatband voltage shift in the C-V hysteresis, which increases with the max sweep voltage. Possible operating mechanisms corresponding to the charging and discharging process in the structure are proposed on the basis of the C-V results.

  17. Oxygen-doped zirconium nitride based transparent resistive random access memory devices fabricated by radio frequency sputtering method

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hee-Dong, E-mail: khd0708@sejong.ac.kr [Department of Electrical Engineering, Sejong University, Neungdong-ro 209, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Yun, Min Ju [Department of Electrical Engineering, Sejong University, Neungdong-ro 209, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Kim, Kyeong Heon [School of Electrical Engineering, Korea University, Anam-dong, Sungbuk-gu, Seoul 163-701 (Korea, Republic of); Kim, Sungho, E-mail: sungho85.kim@sejong.ac.kr [Department of Electrical Engineering, Sejong University, Neungdong-ro 209, Gwangjin-gu, Seoul 143-747 (Korea, Republic of)

    2016-08-05

    In this work, we present a feasibility of bipolar resistive switching (RS) characteristics for Oxygen-doped zirconium nitride (O-doped ZrN{sub x}) films, produced by sputtering method, which shows a high optical transmittance of approximately 78% in the visible region as well as near ultra-violet region. In addition, in a RS test, the device has a large current ratio of 5 × 10{sup 3} in positive bias region and 5 × 10{sup 5} in negative bias region. Then, to evaluate an ability of data storage for the proposed memory devices, we measured a retention time for 10{sup 4} s at room temperature (RT) and 85 °C as well. As a result, the set and reset states were stably maintained with a current ratio of ∼10{sup 2} at 85 °C to ∼10{sup 3} at RT. This result means that the transparent memory by controlling the working pressure during sputtering process to deposit the ZrN{sub x} films could be a milestone for future see-through electronic devices. - Highlights: • The resistive switching characteristics of the transparent O-doped ZrN{sub x}-based RRAM cells have investigated. • Oxygen doping concentration within ZrN{sub x} is optimized using working pressure of sputter. • Long retention time were observed.

  18. Wrist Rehabilitation Device Driven by Pneumatic Flexible Actuator%基于气动柔性驱动器的手腕运动康复装置

    Institute of Scientific and Technical Information of China (English)

    黄磊; 孙中圣; 刘源峰

    2016-01-01

    The several shortcomings exist in the traditional wrist rehabilitation training devices, such as lack of flexibility, complexi structure,high cost and so on. In order to solve the troubles above,this paper designs a wearable wrist rehabilitation device with the flexible pneumatic actuator which can be bended. And it briefly describes the design and manufacturing of this actuator and this de ̄vice. The experiment result shows that the wrist can be driven by the rehabilitation device to do the rehabilitation training very wel,and it is flexible in its movement process.%针对传统的手腕康复训练器存在柔性不足,结构复杂,成本高昂等问题,基于一种可产生弯曲变形的气动柔性驱动器,设计出一种手腕运动康复装置。阐述了气动柔性驱动器和手腕康复装置的设计与制作方法,实验结果表明该手腕康复装置能有效地驱动手腕做运动康复训练,并具有很好的柔性。

  19. Structural design of a newly developed pediatric circulatory assist device for Fontan circulation by using shape memory alloy fiber.

    Science.gov (United States)

    Shiraishi, Y; Sugai, T K; Tanaka, A; Yoshizawa, M; Yambe, T; Yamada, A; Omran, M H; Shiga, T; Kitano, T; Kamiya, K; Mochizuki, S; Miura, H; Homma, D; Yamagishi, M

    2011-01-01

    Total cavopulmonary connection (TCPC) is commonly applied for the surgical treatment of congenital heart disease such as single ventricle in pediatric patients. Patients with no ventricle in pulmonary circulation are treated along with Fontan algorithm, in which the systemic venous return is diverted directly to the pulmonary artery without passing through subpulmonary ventricle. In order to promote the pulmonary circulation after Fontan procedure, we developed a newly designed pulmonary circulatory assist device by using shape memory alloy fibers. We developed a pulmonary circulatory assist device as a non-blood contacting mechanical support system in pediatric patients with TCPC. The device has been designed to be installed like a cuff around the ePTFE TCPC conduit, which can contract from outside. We employed a covalent type functional anisotropic shape memory alloy fiber (Biometal, Toki Corporation, Tokyo Japan) as a servo actuator of the pulmonary circulatory assist device. The diameter of this fiber was 100 microns, and its contractile frequency was 2-3 Hz. Heat generation with electric current contracts these fibers and the conduit. The maximum contraction ratio of this fiber is about 7% in length. In order to extend its contractile ratio, we fabricated and installed mechanical structural units to control the length of fibers. In this study, we examined basic contractile functions of the device in the mock system. As a result, the internal pressure of the conduit increased to 63 mmHg by the mechanical contraction under the condition of 400 msec-current supply in the mock examination with the overflow tank of 10 mmHg loading.

  20. Feasibility study of using a Zener diode as the selection device for bipolar RRAM and WORM memory arrays

    Science.gov (United States)

    Li, Yingtao; Fu, Liping; Tao, Chunlan; Jiang, Xinyu; Sun, Pengxiao

    2014-01-01

    Cross-bar arrays are usually used for the high density application of resistive random access memory (RRAM) devices. However, cross-talk interference limits an increase in the integration density. In this paper, the Zener diode is proposed as a selection device to suppress the sneak current in bipolar RRAM arrays. Measurement results show that the Zener diode can act as a good selection device, and the sneak current can be effectively suppressed. The readout margin is sufficiently improved compared to that obtained without the selection device. Due to the improvement for the reading disturbance, the size of the cross-bar array can be enhanced to more than 103 × 103. Furthermore, the possibility of using a write-once-read-many-times (WORM) cross-bar array is also demonstrated by connecting the Zener diode and the bipolar RRAM in series. These results strongly suggest that using a Zener diode as a selection device opens up great opportunities to realize high density bipolar RRAM arrays.

  1. Ambient atmosphere-processable, printable Cu electrodes for flexible device applications: structural welding on a millisecond timescale of surface oxide-free Cu nanoparticles

    Science.gov (United States)

    Oh, Sang-Jin; Jo, Yejin; Lee, Eun Jung; Lee, Sun Sook; Kang, Young Hun; Jeon, Hye-Ji; Cho, Song Yun; Park, Jin-Seong; Seo, Yeong-Hui; Ryu, Beyong-Hwan; Choi, Youngmin; Jeong, Sunho

    2015-02-01

    Recently, various functional devices based on printing technologies have been of paramount interest, owing to their characteristic processing advantages along with excellent device performance. In particular, printable metallic electrodes have drawn attention in a variety of optoelectronic applications; however, research into printable metallic nanoparticles has been limited mainly to the case of an environmentally stable Ag phase. Despite its earth-abundance and highly conductive nature, the Cu phase, to date, has not been exploited as an ambient atmosphere-processable, printable material due to its critical oxidation problem in air. In this study, we demonstrate a facile route for generating highly conductive, flexible Cu electrodes in air by introducing the well-optimized photonic sintering at a time frame of 10-3 s, at which the photon energy, rather than conventional thermal energy, is instantly provided. It is elucidated here how the surface oxide-free, printed Cu particulate films undergo chemical structural/microstructural evolution depending on the instantly irradiated photon energy, and a successful demonstration is provided of large-area, flexible, printed Cu conductors on various substrates, including polyimide (PI), polyethersulfone (PES), polyethylene terephthalate (PET), and paper. The applicability of the resulting printed Cu electrodes is evaluated via implementation into both flexible capacitor devices and indium-gallium-zinc oxide (IGZO) flexible thin-film transistors.Recently, various functional devices based on printing technologies have been of paramount interest, owing to their characteristic processing advantages along with excellent device performance. In particular, printable metallic electrodes have drawn attention in a variety of optoelectronic applications; however, research into printable metallic nanoparticles has been limited mainly to the case of an environmentally stable Ag phase. Despite its earth-abundance and highly conductive

  2. A carrier transport model in the high-resistance state of lead-methylamine iodide-based resistive memory devices

    Directory of Open Access Journals (Sweden)

    Yongwoo Kwon

    2017-08-01

    Full Text Available Methylamine lead iodide (CH3NH3PbI3, which has recently been in the spotlight as a solar cell material, has also recently shown promise for use as an active material in resistive memory cells with ultralow operation voltages, good transparencies, and flexibilities. The material’s defects, which govern its properties, differ vastly depending on the fabrication process. However, the defect chemistry is not yet entirely understood. We have therefore established a macroscopic transport model with defect-related model parameters, such as trap density, trap energy level, and Fermi level, in order to estimate these parameters for fabricated samples based on their electrical data. Our model will serve as an efficient way to analyze the properties of the active material.

  3. A carrier transport model in the high-resistance state of lead-methylamine iodide-based resistive memory devices

    Science.gov (United States)

    Kwon, Yongwoo; Park, Nayoung; Cha, Pil-Ryung

    2017-08-01

    Methylamine lead iodide (CH3NH3PbI3), which has recently been in the spotlight as a solar cell material, has also recently shown promise for use as an active material in resistive memory cells with ultralow operation voltages, good transparencies, and flexibilities. The material's defects, which govern its properties, differ vastly depending on the fabrication process. However, the defect chemistry is not yet entirely understood. We have therefore established a macroscopic transport model with defect-related model parameters, such as trap density, trap energy level, and Fermi level, in order to estimate these parameters for fabricated samples based on their electrical data. Our model will serve as an efficient way to analyze the properties of the active material.

  4. Durability of rewritable phase-change Ge$_{X}$Sb$_{Y}$ Te$_{1−X−Y}$ memory devices

    Indian Academy of Sciences (India)

    N Parvathala Reddy; Ch Bapanayya; Rajeev Gupta; S C Agarwal

    2013-06-01

    The bond constraint theory (BCT) dealing with the rigidity caused by bond constraints and the long-range potential fluctuations (LRPF) arising from the defects and heterogeneities in the disordered semiconductors are important for understanding the atomic and electronic properties of amorphous semiconductors. Here, they are applied to the already commercialized Ge$_{X}$Sb$_{Y}$ Te$_{1−X−Y}$ (GST) chalcogenide glasses used in the rewritable phase change memory (PCM) devices. The main concern at present is to improve their ability to withstand a large number of phase change cycles, by choosing the right composition. The two considerations (BCT and LRPF) are briefly described and tested on the most commonly used Ge2Sb2Te5 and the nearby compositions. While these considerations provide significant insight into their atomic and electronic structures, the ansatz linking them with the durability of the PCM devices need to be justified by more work.

  5. Influence of Cu diffusion conditions on the switching of Cu-SiO{sub 2}-based resistive memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Thermadam, S. Puthen, E-mail: spchandr@asu.ed [Center for Applied Nanoionics, Arizona State University, Tempe, AZ 85287-6206 (United States); Bhagat, S.K.; Alford, T.L. [School of Materials, Arizona State University, Tempe AZ 85287-8706 (United States); Sakaguchi, Y. [Department of Electrical and Computer Engineering, Boise State University, Boise, ID 83725-2075 (United States); Kozicki, M.N. [Center for Applied Nanoionics, Arizona State University, Tempe, AZ 85287-6206 (United States); Mitkova, M. [Department of Electrical and Computer Engineering, Boise State University, Boise, ID 83725-2075 (United States)

    2010-04-02

    This paper presents a study of Cu diffusion at various temperatures in thin SiO{sub 2} films and the influence of diffusion conditions on the switching of Programmable Metallization Cell (PMC) devices formed from such Cu-doped films. Film composition and diffusion products were analyzed using secondary ion mass spectroscopy, Rutherford backscattering spectrometry, X-ray diffraction and Raman spectroscopy methods. We found a strong dependence of the diffused Cu concentration, which varied between 0.8 at.% and 10{sup -3} at.%, on the annealing temperature. X-ray diffraction and Raman studies revealed that Cu does not react with the SiO{sub 2} network and remains in elemental form after diffusion for the annealing conditions used. PMC resistive memory cells were fabricated with such Cu-diffused SiO{sub 2} films and device performance, including the stability of the switching voltage, is discussed in the context of the material characteristics.

  6. A nonvolatile memory device with very low power consumption based on the switching of a standard electrode potential

    Directory of Open Access Journals (Sweden)

    Issei Sugiyama

    2017-04-01

    Full Text Available We prepared a nonvolatile memory device that could be reversibly switched between a high and a low open-circuit voltage (Voc regime. The device is composed of a solid electrolyte Li3PO4 film sandwiched between metal Li and Au electrodes: a Li/Li3PO4/Au heterostructure, which was fabricated at room temperature on a glass substrate. The bistable states at Voc ∼ 0.7 and ∼0.3 V could be reversibly switched by applying an external voltage of 2.0 and 0.18 V, respectively. The formation and deformation of an ultrathin Au–Li alloy at the Li3PO4/Au electrode interface were the origin of the reversible switching.

  7. Sulfur and Nitrogen co-doped graphene quantum dot decorated ZnO nanorod/polymer hybrid flexible device for photosensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Hmar, Jehova Jire L.; Majumder, Tanmoy; Dhar, Saurab; Mondal, Suvra Prakash, E-mail: suvraphy@gmail.com

    2016-08-01

    S and N co-doped graphene quantum dots (S,N-GQDs) have been synthesized by a hydrothermal process. S,N-GQDs are made up of 1–5 monolayer of graphene with average diameter 13.3 nm. The absorption peaks at 336 and 621 nm, are attributed to n → Π{sup ⁎} transitions of electrons in C=O and S=O bonds, respectively. S,N-GQDs are highly luminescent and showed excitation dependent emission behaviors. Hybrid photosensing device has been fabricated with S,N-GQD sensitized ZnO nanorods and a conjugated polymer poly(3-hexylthiophene) (P3HT). S,N-GQD decorated ZnO nanorod demonstrated higher photoresponse compared to pristine ZnO nanorod based device. S,N-GQD/ZnO nanorod hybrid device showed superior incident photon to electron conversion efficiency (IPCE), photoresponsivity and detectivity compared to the control samples. The flexibility study of the samples has been monitored by measuring current-voltage characteristics at different bending angles. - Highlights: • S and N co-doped graphene quantum dots (S,N-GQDs) were synthesized. • ZnO nanorods were grown on ITO coated flexible PET substrates. • S,N-GQDs were attached with ZnO nanorods and used as a green sensitizer. • Photosensing properties of S,N-GQD/ZnO and P3HT polymer hybrid device was studied.

  8. An Annotated Bibliography of High-Voltage Direct-Current Transmission and Flexible AC Transmission (FACTS) Devices, 1991-1993.

    Energy Technology Data Exchange (ETDEWEB)

    Litzenberger, Wayne; Lava, Val

    1994-08-01

    References are contained for HVDC systems, converter stations and components, overhead transmission lines, cable transmission, system design and operations, simulation of high voltage direct current systems, high-voltage direct current installations, and flexible AC transmission system (FACTS).

  9. Experimental Validation of Condition Monitoring for Electrically Activated Shape Memory Alloys for an Unlocking Device

    Science.gov (United States)

    Rathmann, Christian; Theren, Benedict; Fleczok, Benjamin; Kuhlenkötter, Bernd

    2017-06-01

    Shape memory alloys (SMA) belong to the group functional materials which can be activated thermally. Along with a phase transformation, they can remember a previously imprinted shape and have a special resistance behavior. Therefore, they can also be used as a sensor and may be capable of detecting various system states in technical systems. This paper makes a contribution by evaluating the measurability of measured variables by SMA elements. Furthermore, it investigates the technically relevant states of “blockade” and “activation” of electrically activated shape memory actuators. It develops and validates an algorithm which is able to detect a possible “blockade”. Moreover, this work presents a hardware concept for a condition monitoring system of shape memory actuators.

  10. A low temperature processed Si-quantum-dot poly-Si TFT nonvolatile memory device

    Institute of Scientific and Technical Information of China (English)

    Sun Wei

    2013-01-01

    This paper reports on a successful demonstration of poly-Si TFT nonvolatile memory with a much reduced thermal-budget.The TFT uses uniform Si quantum-dots (size ~10 nm and density ~1011 cm-2) asstorage media,obtained via LPCVD by flashing SiH4/H2 at 580 ℃ for 15 s on a Si3N4 surface.The poly-Si grain-enlargement step was shifted after source/drain formation.The NiSix-silicided source/drain enables a fast lateral-recrystallization,and thus grain-enlargement can be accomplished by a much reduced thermal-cycle (i.e.,550 ℃/4 h).The excellent memory characteristics suggest that the proposed poly-Si TFT Si quantum-dot memory and associated processes are promising for use in wider TFT applications,such as system-on-glass.

  11. Resistive Switching in All-Printed, Flexible and Hybrid MoS2-PVA Nanocomposite based Memristive Device Fabricated by Reverse Offset

    Science.gov (United States)

    Rehman, Muhammad Muqeet; Siddiqui, Ghayas Uddin; Gul, Jahan Zeb; Kim, Soo-Wan; Lim, Jong Hwan; Choi, Kyung Hyun

    2016-11-01

    Owing to the increasing interest in the nonvolatile memory devices, resistive switching based on hybrid nanocomposite of a 2D material, molybdenum disulphide (MoS2) and polyvinyl alcohol (PVA) is explored in this work. As a proof of concept, we have demonstrated the fabrication of a memory device with the configuration of PET/Ag/MoS2-PVA/Ag via an all printed, hybrid, and state of the art fabrication approach. Bottom Ag electrodes, active layer of hybrid MoS2-PVA nanocomposite and top Ag electrode are deposited by reverse offset, electrohydrodynamic (EHD) atomization and electrohydrodynamic (EHD) patterning respectively. The fabricated device displayed characteristic bistable, nonvolatile and rewritable resistive switching behavior at a low operating voltage. A decent off/on ratio, high retention time, and large endurance of 1.28 × 102, 105 sec and 1000 voltage sweeps were recorded respectively. Double logarithmic curve satisfy the trap controlled space charge limited current (TCSCLC) model in high resistance state (HRS) and ohmic model in low resistance state (LRS). Bendability test at various bending diameters (50-2 mm) for 1500 cycles was carried out to show the mechanical robustness of fabricated device.

  12. Memory device sensitivity trends in aircraft's environment; Evolution de la sensibilite de composants memoires en altitude avion

    Energy Technology Data Exchange (ETDEWEB)

    Bouchet, T.; Fourtine, S. [Aerospatiale-Matra Airbus, 31 - Toulouse (France); Calvet, M.C. [Aerospatiale-Matra Lanceur, 78 - Les Mureaux (France)

    1999-07-01

    The authors present the SEU (single event upset) sensitivity of 31 SRAM (static random access memory) and 8 DRAM (dynamic random access memory) according to their technologies. 2 methods have been used to compute the SEU rate: the NCS (neutron cross section) method and the BGR (burst generation rate) method, the physics data required by both methods have been either found in scientific literature or directly measured. The use of new technologies implies a quicker time response through a dramatic reduction of chip size and of the amount of energy representing 1 bit. The reduction of size makes less particles are likely to interact with the chip but the reduction of the critical charge implies that these interactions are more likely to damage the chip. The SEU sensitivity is then parted between these 2 opposed trends. Results show that for technologies beyond 0,18 {mu}m these 2 trends balance roughly. Nevertheless the feedback experience shows that the number of errors is increasing. This is due to the fact that avionics requires more and more memory to perform numerical functions, the number of bits is increasing so is the risk of errors. As far as SEU is concerned, RAM devices are less and less sensitive comparatively for 1 bit, and DRAM seem to be less sensitive than SRAM. (A.C.)

  13. Flexibility and rigidity, requirements for the function of proteins and protein pigment complexes. Eleventh Keilin memorial lecture.

    Science.gov (United States)

    Huber, R

    1987-12-01

    Proteins may be rigid or flexible to various degrees as required for optimum function. Flexibility at the level of amino acid side-chains occurs universally and is important for binding and catalysis. Flexibility of large parts of a protein which rearrange or move are particularly interesting and will be discussed here. We differentiate between certain categories of large-scale flexibility although the boundaries between them are diffuse: flexibility of peptide segments, domain motions and order-disorder transitions of spatially contigous regions. The domains may be flexibly linked to allow rather unrestricted motion or the motion may be constrained to certain modes. The polypeptide segments linking the domains show characteristic structural features. The various categories of flexibility will be illustrated with the following examples. (a) Small protein proteinase inhibitors which are rather rigid molecules which provide binding surfaces complementary to their cognate proteases, but also show limited segmental flexibility and adaptation. (b) Large plasma inhibitors which exhibit large conformational changes upon interaction with proteases probably for regulatory purposes. (c) Pancreatic serine proteases which employ a disorder-order transition of their activation domain as a means to regulate enzymic activity. (d) Immunoglobulins in which rather unrestricted and also hinged domain motions occur in different parts of the molecule probably to allow binding to antigens in different arrangements. (e) Citrate synthase which adopts open and closed forms by a hinged domain motion to bind substrates and release products and to perform the catalytic condensation reaction, respectively. (f) The bifunctional multienzyme complex riboflavin synthase in which two enzymes (alpha and beta) catalyse two consecutive enzymic reactions. The beta-subunits form a shell, in which the alpha-subunits are enclosed. Diffusional motion of the catalytic intermediates is therefore restricted

  14. Development of a thermodynamic control system for the Fontan circulation pulsation device using shape memory alloy fibers.

    Science.gov (United States)

    Yamada, Akihiro; Shiraishi, Yasuyuki; Miura, Hidekazu; Hashem, Hashem Mohamed Omran; Tsuboko, Yusuke; Yamagishi, Masaaki; Yambe, Tomoyuki

    2015-09-01

    The Fontan procedure is one of the common surgical treatments for circulatory reconstruction in pediatric patients with congenital heart disease. In Fontan circulation, low pulsatility may induce localized lung ischemia and may impair the development of pulmonary peripheral endothelial cells. To promote pulmonary circulation in Fontan circulation, we have been developing a pediatric pulmonary circulatory pulsation device using shape memory alloy fibers attached from the outside of total cavopulmonary connection. In this study, we developed a new thermal control system for the device and examined its functions. We mounted on the device 16 fibers connected in parallel around an ePTFE graft circumferentially. To provide optimized contraction, we designed the new thermal control system. The system consisted of a thermistor, a pressure sensor, and a regulator that was controlled by the adaptive thermodynamic transfer functions. We monitored the parameters and calculated heat transfer function as well as pressure distribution on the graft surface. Then we examined and compared the dynamic contractile pressure and changes in surface temperature. As a result, by the application of the control based on the new feedback system analysis, the circumferential contractile pressure increased by 35%. The adaptive thermodynamic regulation was useful for the selection of alternative thresholds of the surface temperature of the graft. The system could achieve effective contraction for the pulsatile flow generation by the device.

  15. Development of a high capacity bubble domain memory element and related epitaxial garnet materials for application in spacecraft data recorders. Item 2: The optimization of material-device parameters for application in bubble domain memory elements for spacecraft data recorders

    Science.gov (United States)

    Besser, P. J.

    1976-01-01

    Bubble domain materials and devices are discussed. One of the materials development goals was a materials system suitable for operation of 16 micrometer period bubble domain devices at 150 kHz over the temperature range -10 C to +60 C. Several material compositions and hard bubble suppression techniques were characterized and the most promising candidates were evaluated in device structures. The technique of pulsed laser stroboscopic microscopy was used to characterize bubble dynamic properties and device performance at 150 kHz. Techniques for large area LPE film growth were developed as a separate task. Device studies included detector optimization, passive replicator design and test and on-chip bridge evaluation. As a technology demonstration an 8 chip memory cell was designed, tested and delivered. The memory elements used in the cell were 10 kilobit serial registers.

  16. Fabrication of Nano-Crossbar Resistive Switching Memory Based on the Copper-Tantalum Pentoxide-Platinum Device Structure

    Science.gov (United States)

    Olga Gneri, Paula; Jardim, Marcos

    Resistive switching memory has been of interest lately not only for its simple metal-insulator-metal (MIM) structure but also for its promising ease of scalability an integration into current CMOS technologies like the Field Programmable Gate Arrays and other non-volatile memory applications. There are several resistive switching MIM combinations but under this scope of research, attention will be paid to the bipolar resistive switching characteristics and fabrication of Tantalum Pentaoxide sandwiched between platinum and copper. By changing the polarity of the voltage bias, this metal-insulator-metal (MIM) device can be switched between a high resistive state (OFF) and low resistive state (ON). The change in states is induced by an electrochemical metallization process, which causes a formation or dissolution of Cu metal filamentary paths in the Tantalum Pentaoxide insulator. There is very little thorough experimental information about the Cu-Ta 2O5-Pt switching characteristics when scaled to nanometer dimensions. In this light, the MIM structure was fabricated in a two-dimensional crossbar format. Also, with the limited available resources, a multi-spacer technique was formulated to localize the active device area in this MIM configuration to less than 20nm. This step is important in understanding the switching characteristics and reliability of this structure when scaled to nanometer dimensions.

  17. Highly transparent and flexible bio-based polyimide/TiO2 and ZrO2 hybrid films with tunable refractive index, Abbe number, and memory properties

    Science.gov (United States)

    Huang, Tzu-Tien; Tsai, Chia-Liang; Tateyama, Seiji; Kaneko, Tatsuo; Liou, Guey-Sheng

    2016-06-01

    The novel bio-based polyimide (4ATA-PI) and the corresponding PI hybrids of TiO2 or ZrO2 with excellent optical properties and thermal stability have been prepared successfully. The highly transparent 4ATA-PI containing carboxylic acid groups in the backbone could provide reaction sites for organic-inorganic bonding to obtain homogeneous hybrid films. These PI hybrid films showed a tunable refractive index (1.60-1.81 for 4ATA-PI/TiO2 and 1.60-1.80 for 4ATA-PI/ZrO2), and the 4ATA-PI/ZrO2 hybrid films revealed a higher optical transparency and Abbe's number than those of the 4ATA-PI/TiO2 system due to a larger band gap of ZrO2. By introducing TiO2 and ZrO2 as the electron acceptor into the 4ATA-PI system, the hybrid materials have a lower LUMO energy level which could facilitate and stabilize the charge transfer complex. Therefore, memory devices derived from these PI hybrid films exhibited tunable memory properties from DRAM, SRAM, to WORM with a different TiO2 or ZrO2 content from 0 wt% to 50 wt% with a high ON/OFF ratio (108). In addition, the different energy levels of TiO2 and ZrO2 revealed specifically unique memory characteristics, implying the potential application of the prepared 4ATA-PI/TiO2 and 4ATA-PI/ZrO2 hybrid films in highly transparent memory devices.The novel bio-based polyimide (4ATA-PI) and the corresponding PI hybrids of TiO2 or ZrO2 with excellent optical properties and thermal stability have been prepared successfully. The highly transparent 4ATA-PI containing carboxylic acid groups in the backbone could provide reaction sites for organic-inorganic bonding to obtain homogeneous hybrid films. These PI hybrid films showed a tunable refractive index (1.60-1.81 for 4ATA-PI/TiO2 and 1.60-1.80 for 4ATA-PI/ZrO2), and the 4ATA-PI/ZrO2 hybrid films revealed a higher optical transparency and Abbe's number than those of the 4ATA-PI/TiO2 system due to a larger band gap of ZrO2. By introducing TiO2 and ZrO2 as the electron acceptor into the 4ATA-PI system

  18. Feasibility of Crosslinked Acrylic Shape Memory Polymer for a Thrombectomy Device

    Directory of Open Access Journals (Sweden)

    Andrea D. Muschenborn

    2014-01-01

    Full Text Available Purpose. To evaluate the feasibility of utilizing a system of SMP acrylates for a thrombectomy device by determining an optimal crosslink density that provides both adequate recovery stress for blood clot removal and sufficient strain capacity to enable catheter delivery. Methods. Four thermoset acrylic copolymers containing benzyl methacrylate (BzMA and bisphenol A ethoxylate diacrylate (Mn∼512, BPA were designed with differing thermomechanical properties. Finite element analysis (FEA was performed to ensure that the materials were able to undergo the strains imposed by crimping, and fabricated devices were subjected to force-monitored crimping, constrained recovery, and bench-top thrombectomy. Results. Devices with 25 and 35 mole% BPA exhibited the highest recovery stress and the highest brittle response as they broke upon constrained recovery. On the contrary, the 15 mole% BPA devices endured all testing and their recovery stress (5 kPa enabled successful bench-top thrombectomy in 2/3 times, compared to 0/3 for the devices with the lowest BPA content. Conclusion. While the 15 mole% BPA devices provided the best trade-off between device integrity and performance, other SMP systems that offer recovery stresses above 5 kPa without increasing brittleness to the point of causing device failure would be more suitable for this application.

  19. Low-temperature process steps for realization of non-volatile memory devices

    NARCIS (Netherlands)

    Brunets, I.; Boogaard, A.; Aarnink, A.A.I.; Kovalgin, A.Y.; Wolters, R.A.M.; Holleman, J.; Schmitz, J.

    2007-01-01

    In this work, the low-temperature process steps required for the realization of nano-crystal non-volatile memory cells are discussed. An amorphous silicon film, crystallized using a diode pumped solid state green laser irradiating at 532 nm, is proposed as an active layer. The deposition of the subs

  20. High-performance flexible electrochromic device based on facile semiconductor-to-metal transition realized by WO3·2H2O ultrathin nanosheets

    Science.gov (United States)

    Liang, Lin; Zhang, Jiajia; Zhou, Yingying; Xie, Junfeng; Zhang, Xiaodong; Guan, Meili; Pan, Bicai; Xie, Yi

    2013-01-01

    Ultrathin nanosheets are considered as one kind of the most promising candidates for the fabrication of flexible electrochromic devices (ECDs) due to their permeable channels, high specific surface areas, and good contact with the substrate. Herein, we first report the synthesis of large-area nanosheets of tungsten oxide dihydrate (WO3·2H2O) with a thickness of only about 1.4 nm, showing much higher Li+ diffusion coefficients than those of the bulk counterpart. The WO3·2H2O ultrathin nanosheets are successfully assembled into the electrode of flexible electrochromic device, which exhibits wide optical modulation, fast color-switching speed, high coloration efficiency, good cyclic stability and excellent flexibility. Moreover, the electrochromic mechanism of WO3·2H2O is further investigated by first-principle density functional theory (DFT) calculations, in which the relationship between structural features of ultrathin nanosheets and coloration/bleaching response speed is revealed. PMID:23728489

  1. Controlling methods of a newly developed extra aortic counter-pulsation device using shape memory alloy fibers.

    Science.gov (United States)

    Hashem, Mohamed O; Yamada, A; Tsuboko, Y; Muira, H; Homma, D; Shiraishi, Y; Yambe, T

    2013-01-01

    Diastolic counter-pulsation has been used to provide circulatory augmentation for short term cardiac support. The success of intra-aortic balloon pump (IABP) therapy has generated interest in long term counter-pulsation strategies to treat heart failure patients. The authors have been developing a totally implantable extra aortic pulsation device for the circulatory support of heart failure patients, using 150 µm Ni-Ti anisotropic shape memory alloy (SMA) fibers. These fibers contract by Joule heating with an electric current supply. The special features of our design are as follow: non blood contacting, extra aortic pulsation function synchronizing with the native heart, a wrapping mechanical structure for the aorta in order to achieve its assistance as the aortomyoplsty and the extra aortic balloon pump. The device consisted of rubber silicone wall plates, serially connected for radial contraction. We examined the contractile function of the device, as well as it controlling methods; the phase delay parameter and the pulse width modulation, in a systemic mock circulatory system, with a pneumatically driven silicone left ventricle model, arterial rubber tubing, a peripheral resistance unit, and a venous reservoir. The device was secured around the aortic tubing with a counter-pulsation mode of 1:4 against the heartbeat. Pressure and flow waveforms were measured at the aortic outflow, as well as its driving condition of the contraction phase width and the phase delay. The device achieved its variable phase control for co-pulsation or counter-pulsation modes by changing the phase delay of the SMA fibers. Peak diastolic pressure significantly augmented, mean flow increased (p<0.05) according to the pulse width modulation. Therefore the newly developed extra aortic counter-pulsation device using SMA fibers, through it controlling methods indicated its promising alternative extra aortic approach for non-blood contacting cardiovascular circulatory support.

  2. Highly transparent and flexible bio-based polyimide/TiO2 and ZrO2 hybrid films with tunable refractive index, Abbe number, and memory properties.

    Science.gov (United States)

    Huang, Tzu-Tien; Tsai, Chia-Liang; Tateyama, Seiji; Kaneko, Tatsuo; Liou, Guey-Sheng

    2016-07-07

    The novel bio-based polyimide (4ATA-PI) and the corresponding PI hybrids of TiO2 or ZrO2 with excellent optical properties and thermal stability have been prepared successfully. The highly transparent 4ATA-PI containing carboxylic acid groups in the backbone could provide reaction sites for organic-inorganic bonding to obtain homogeneous hybrid films. These PI hybrid films showed a tunable refractive index (1.60-1.81 for 4ATA-PI/TiO2 and 1.60-1.80 for 4ATA-PI/ZrO2), and the 4ATA-PI/ZrO2 hybrid films revealed a higher optical transparency and Abbe's number than those of the 4ATA-PI/TiO2 system due to a larger band gap of ZrO2. By introducing TiO2 and ZrO2 as the electron acceptor into the 4ATA-PI system, the hybrid materials have a lower LUMO energy level which could facilitate and stabilize the charge transfer complex. Therefore, memory devices derived from these PI hybrid films exhibited tunable memory properties from DRAM, SRAM, to WORM with a different TiO2 or ZrO2 content from 0 wt% to 50 wt% with a high ON/OFF ratio (10(8)). In addition, the different energy levels of TiO2 and ZrO2 revealed specifically unique memory characteristics, implying the potential application of the prepared 4ATA-PI/TiO2 and 4ATA-PI/ZrO2 hybrid films in highly transparent memory devices.

  3. A flexible triboelectric-piezoelectric hybrid nanogenerator based on P(VDF-TrFE) nanofibers and PDMS/MWCNT for wearable devices

    Science.gov (United States)

    Wang, Xingzhao; Yang, Bin; Liu, Jingquan; Zhu, Yanbo; Yang, Chunsheng; He, Qing

    2016-11-01

    This paper studied and realized a flexible nanogenerator based on P(VDF-TrFE) nanofibers and PDMS/MWCNT thin composite membrane, which worked under triboelectric and piezoelectric hybrid mechanisms. The P(VDF-TrFE) nanofibers as a piezoelectric functional layer and a triboelectric friction layer are formed by electrospinning process. In order to improve the performance of triboelectric nanogenerator, the multiwall carbon nanotubes (MWCNT) is doped into PDMS patterned films as the other flexible friction layer to increase the initial capacitance. The flexible nanogenerator is fabricated by low cost MEMS processes. Its output performance is characterized in detail and structural optimization is performed. The device’s output peak-peak voltage, power and power density under triboelectric mechanism are 25 V, 98.56 μW and 1.98 mW/cm3 under the pressure force of 5 N, respectively. The output peak-peak voltage, power and power density under piezoelectric working principle are 2.5 V, 9.74 μW, and 0.689 mW/cm3 under the same condition, respectively. We believe that the proposed flexible, biocompatible, lightweight, low cost nanogenerator will supply effective power energy sustainably for wearable devices in practical applications.

  4. Flexible attention allocation to visual and auditory working memory tasks : manipulating reward induces a trade-off

    NARCIS (Netherlands)

    Morey, Candice Coker; Cowan, Nelson; Morey, Richard D.; Rouder, Jeffery N.

    2011-01-01

    Prominent roles for general attention resources are posited in many models of working memory, but the manner in which these can be allocated differs between models or is not sufficiently specified. We varied the payoffs for correct responses in two temporally-overlapping recognition tasks, a visual

  5. Fabrication of a micro through-hole array by gas-blowing a PDMS-treated polyamide screen for a flexible drag-reducing skin-like device

    Science.gov (United States)

    Li, Yong; Zhou, Kai; Zhao, Xiang; Kong, Quancun

    2017-01-01

    We propose a method for fabricating a flexible skin-like device for generating and trapping micro bubbles with the aim of reducing underwater drag. This low-cost, efficient, high-pressure gas-blow method is used to fabricate a micro through-hole array in a flexible polydimethylsiloxane (PDMS) gel-based skin. The key parameters in the gas-blowing method are investigated, such as the viscosity of PDMS and the blowing pressure in order to optimize the quality of through-hole layer. Deviation of the linear dimensions of the obtained micro holes was less than 4.5%. In addition, multiphase computational fluid dynamics models were built to analyze the drag-reduction performance of bell-shaped holes made by this method. Compared with cylindrical through holes produced by molding, the drag-reduction effect of bell-shaped holes increased as much as 34%.

  6. Reduction of RESET current in phase change memory devices by carbon doping in GeSbTe films

    Science.gov (United States)

    Park, J. H.; Kim, S.-W.; Kim, J. H.; Wu, Z.; Cho, S. L.; Ahn, D.; Ahn, D. H.; Lee, J. M.; Nam, S. U.; Ko, D.-H.

    2015-03-01

    Phase Change Memory (PCM) has been proposed for use as a substitute for flash memory to satisfy the huge demands for high performance and reliability that promise to come in the next generation. In spite of its high scalability, reliability, and simple structure, high writing current, e.g., RESET current, has been a significant obstacle to achieving a high density in storage applications and the low power consumption required for use in mobile applications. We report herein on an attempt to determine the level of carbon incorporated into a GeSbTe (GST) film that is needed to reduce the RESET current of PCM devices. The crystal structure of the film was transformed into an amorphous phase by carbon doping, the stability of which was enhanced with increasing carbon content. This was verified by the small grain size and large band gap that are typically associated with carbon. The increased level of C-Ge covalent bonding is responsible for these enhancements. Thus, the resistance of the carbon doped Ge2Sb2Te5 film was higher than that for an undoped GST film by a factor of 2 orders of magnitude after producing a stable face-centered cubic phase by annealing. As a consequence, the PCM devices showed a significant reduction in RESET current as low as 23% when the carbon content was increased to 11.8 at. %. This can be attributed to the elevated SET resistance, which is proportional to the dynamic resistance of the PCM device, caused by the high resistance due to a carbon doped GST film.

  7. SEMICONDUCTOR DEVICES: Reducing the influence of STI on SONOS memory through optimizing added boron implantation technology

    Science.gov (United States)

    Yue, Xu; Feng, Yan; Zhiguo, Li; Fan, Yang; Yonggang, Wang; Jianguang, Chang

    2010-09-01

    The influence of shallow trench isolation (STI) on a 90 nm polysilicon-oxide-nitride-oxide-silicon structure non-volatile memory has been studied based on experiments. It has been found that the performance of edge memory cells adjacent to STI deteriorates remarkably. The compressive stress and boron segregation induced by STI are thought to be the main causes of this problem. In order to mitigate the STI impact, an added boron implantation in the STI region is developed as a new solution. Four kinds of boron implantation experiments have been implemented to evaluate the impact of STI on edge cells, respectively. The experimental results show that the performance of edge cells can be greatly improved through optimizing added boron implantation technology.

  8. Memory devices with encapsulated Si nano-crystals: Realization and Characterization.

    NARCIS (Netherlands)

    Brunets, I.; Hemert, van T.; Boogaard, A.; Aarnink, A.A.I.; Kovalgin, A.Y.; Holleman, J.; Schmitz, J.

    2006-01-01

    In this work, the advanced non-volatile memory design based on silicon nano-crystals instead of conventional continuous floating gate was explored The multilayer Al/TiN/Al2O3/Si-nano-crystals/Al2O3/SiO2/Si(100) structure was realized. The functional layer stack (TiN/Al2O3/Si-nano-crystals/Al2O3) was

  9. SEMICONDUCTOR DEVICES Effect of trapped charge accumulation on the retention of charge trapping memory

    Science.gov (United States)

    Rui, Jin; Xiaoyan, Liu; Gang, Du; Jinfeng, Kang; Ruqi, Han

    2010-12-01

    The accumulation process of trapped charges in a TANOS cell during P/E cycling is investigated via numerical simulation. The recombination process between trapped charges is an important issue on the retention of charge trapping memory. Our results show that accumulated trapped holes during P/E cycling can have an influence on retention, and the recombination mechanism between trapped charges should be taken into account when evaluating the retention capability of TANOS.

  10. Characterizations and thermal stability improvement of phase-change memory device containing Ce-doped GeSbTe films

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yu-Jen; Tsai, Min-Chuan; Wang, Chiung-Hsin; Hsieh, Tsung-Eong, E-mail: tehsieh@mail.nctu.edu.tw

    2012-02-29

    Phase-transition temperature of GeSbTe (GST) chalcogenide film was drastically increased from 159 to 236 Degree-Sign C by cerium (Ce) doping (up to 8.6 at.%) without altering the resistivity property of GST. Grain refinement via the solid-solution mechanism and the amplification of p-type semiconducting behavior in Ce-doped GST were observed. They were correlated with the enhancement of thermal stability and data retention property of GST as revealed by exothermal and isothermal analyses. Phase-change memory (PCM) device characterized at various temperatures revealed an effective thermal stability improvement on the threshold voltage of PCM device by Ce doping. - Highlights: Black-Right-Pointing-Pointer Ce doping increased phase-change temperature of GST from 159 to 236 Degree-Sign C. Black-Right-Pointing-Pointer No suppression of resistivity level in amorphous Ce-doped GST. Black-Right-Pointing-Pointer Resistance ratio of amorphous and crystalline Ce-doped GST was preserved at 10{sup 5}. Black-Right-Pointing-Pointer p-type semiconducting behavior of GST was enhanced by Ce-doping. Black-Right-Pointing-Pointer Ce-doping improved the thermal stability of threshold voltage of GST PCM device.

  11. All-polymer bistable resistive memory device based on nanoscale phase-separated PCBM-ferroelectric blends

    KAUST Repository

    Khan, Mohammad A.

    2012-11-21

    All polymer nonvolatile bistable memory devices are fabricated from blends of ferroelectric poly(vinylidenefluoride-trifluoroethylene (P(VDF-TrFE)) and n-type semiconducting [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The nanoscale phase separated films consist of PCBM domains that extend from bottom to top electrode, surrounded by a ferroelectric P(VDF-TrFE) matrix. Highly conducting poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) polymer electrodes are used to engineer band offsets at the interfaces. The devices display resistive switching behavior due to modulation of this injection barrier. With careful optimization of the solvent and processing conditions, it is possible to spin cast very smooth blend films (Rrms ≈ 7.94 nm) and with good reproducibility. The devices exhibit high Ion/I off ratios (≈3 × 103), low read voltages (≈5 V), excellent dielectric response at high frequencies (Ïμr ≈ 8.3 at 1 MHz), and excellent retention characteristics up to 10 000 s. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Homo-junction ferroelectric field-effect-transistor memory device using solution-processed lithium-doped zinc oxide thin films

    KAUST Repository

    Nayak, Pradipta K.

    2012-06-22

    High performance homo-junction field-effect transistor memory devices were prepared using solution processed transparent lithium-doped zinc oxide thin films for both the ferroelectric and semiconducting active layers. A highest field-effect mobility of 8.7 cm2/Vs was obtained along with an Ion/Ioff ratio of 106. The ferroelectric thin filmtransistors showed a low sub-threshold swing value of 0.19 V/dec and a significantly reduced device operating voltage (±4 V) compared to the reported hetero-junction ferroelectrictransistors, which is very promising for low-power non-volatile memory applications.

  13. Resistive switching characteristics and conduction mechanisms of nonvolatile memory devices based on Ga and Sn co-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Dohyun; Yun, Dong Yeol; Lee, Nam Hyun; Kim, Tae Whan, E-mail: twk@hanyang.ac.kr

    2015-07-31

    Nonvolatile memory devices were fabricated utilizing Ga and Sn co-doped ZnO (GZTO) films formed by using a solution process method. X-ray diffraction patterns showed that the crystallinity of the annealed GZTO films was an amorphous phase. X-ray photoelectron spectroscopy spectra of the GZTO films depicted Zn−O, Ga−O, and Sn−O bonds. Current–voltage measurements on the Al/GZTO/indium-tin-oxide (ITO) devices at 300 K showed bipolar resistive switching behaviors. The resistances at both the low resistance state (LRS) and high resistance state (HRS) measured at 0.5 V for the devices maintain almost constant without any damage and breakdown above 130 s, indicative of the memory stability of the devices. A difference in the resistance between the HRS and the LRS was more than 1 order of the magnitude. The conduction mechanisms of the HRS in the set process for the Al/GZTO/ITO devices were dominated by a space-charge-limited current model. - Highlights: • Nonvolatile memory devices were fabricated utilizing Ga and Sn co-doped ZnO (GZTO) films. • X-ray diffraction patterns showed that the annealed GZTO films were an amorphous phase. • Current–voltage measurements on the devices showed bipolar resistive switching behaviors. • One order magnitude difference in resistance between low and high resistance states (HRS) • Space charge limited conduction is the dominant conduction mechanisms of the HRS.

  14. Filament theory based WORM memory devices using aluminum/poly(9-vinylcarbazole)/aluminum structures.

    Science.gov (United States)

    Suresh, Aswin; Krishnakumar, Govind; Namboothiry, Manoj A G

    2014-07-14

    Spin coated poly(N-vinylcarbazole) (PVK) sandwiched between thermally evaporated aluminum (Al) electrodes on a glass substrate showed unipolar Write Once Read Many times (WORM) characteristics. The pristine devices were in the low resistance ON state exhibiting ohmic behavior and at a voltage near -2 V, they switched abruptly to the high resistance OFF state showing space charge limited current (SCLC). We suggest that the rupturing of metallic filaments due to Joule heating may explain the effect. The WORM devices exhibited an ON/OFF ratio of 10(8), a retention of 1000 s and an endurance of ∼10(6) cycles in both ON and OFF states.

  15. Investigation on the relationship between CD and CDU in memory devices

    Science.gov (United States)

    Park, Jeongsu; Kim, Daewoo; Kim, Keunjun; Kim, Choidong; Lee, Sungkoo; Kim, Hyeongsoo

    2016-03-01

    As pattern design rule of device shrinks, CD control becomes more critical and important especially for resistance devices. As CD (Critical Dimension) increases, CDU (Critical Dimension Uniformity) becomes worse generally. The question with this relationship is a starting point of our study. Mainly we focused on two points. One is which factor affects CDU. The other is whether CDU degradation with large CD happens at all cases or not. We have analyzed with simulation and experiment results about CDU with splitted mask layout CD under limited conditions such as same equipment, illumination and exposure dose. As a result, we will show the relationship between CD size and CDU.

  16. Fabrication of graphene-nanoflake/poly(4-vinylphenol) polymer nanocomposite thin film by electrohydrodynamic atomization and its application as flexible resistive switching device

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyung Hyun; Ali, Junaid [Department of Mechatronics Engineering, Jeju National University, Jeju 690-756 (Korea, Republic of); Na, Kyoung-Hoan, E-mail: khna@dankook.ac.kr [College of Engineering, Dankook University, Yongin-si, Gyeonggi-do 448-701 (Korea, Republic of)

    2015-10-15

    This paper describes synthesis of graphene/poly(4-vinylphenol) (PVP) nanocomposite and deposition of thin film by electrohydrodynamic atomization (EHDA) for fabrication flexible resistive switching device. EHDA technique proved its viability for thin film deposition after surface morphology analyses by field emission scanning electron microscope (FESEM) and non-destructive 3D Nano-profilometry, as the deposited films were, devoid of abnormalities. The commercially available graphene micro-flakes were exfoliated and broken down to ultra-small (20 nm–200 nm) nano-flakes by ultra-sonication in presence of N-methyl-pyrrolidone (NMP). These graphene nanoflakes with PVP nanocomposite, were successfully deposited as thin films (thickness ~140±7 nm, R{sub a}=2.59 nm) on indium–tin-oxide (ITO) coated polyethylene terephthalate (PET) substrate. Transmittance data revealed that thin films are up to ~87% transparent in visible and NIR region. Resistive switching behaviour of graphene/PVP nanocomposite thin film was studied by using the nanocomposite as active layer in Ag/active layer/ITO sandwich structure. The resistive switching devices thus fabricated, showed characteristic OFF to ON (high resistance to low resistance) transition at low voltages, when operated between ±3 V, characterized at 10 nA compliance currents. The devices fabricated by this approach exhibited a stable room temperature, low power current–voltage hysteresis and well over 1 h retentivity, and R{sub OFF}/R{sub ON}≈35:1. The device showed stable flexibility up to a minimum bending diameter of 1.8 cm.

  17. New internalized distraction device for craniofacial plastic surgery using Ni-free, Ti-based shape memory alloy.

    Science.gov (United States)

    Kanetaka, Hiroyasu; Shimizu, Yoshinaka; Kudo, Tada-aki; Zhang, Ye; Kano, Mitsuhiro; Sano, Yuya; Ichikawa, Hiroyuki; Hosoda, Hideki; Miyazaki, Shuichi

    2010-11-01

    This study was undertaken to examine effects and biocompatibility of a new internalized distraction device made from newly developed Ti-Nb-Al shape memory alloy (SMA). Crania of Wistar rats were expanded using a U-shaped wire of this SMA set on each cranium in an experimental group. At 2 or 4 weeks after operation, the rats were killed; width measurements and three-dimensional observations of crania were conducted using soft x-ray and microfocus x-ray computed tomography photography. After photography, histologic sections were made and stained with hematoxylin and eosin. No pathologic change in the experimental duration was observed macroscopically or histologically. Significantly increased size was found for the rat crania in the experimental group compared with the control group. Results demonstrated the feasibility and biocompatibility of internalized distraction osteogenesis using Ni-free, Ti-based SMA in craniofacial plastic surgery for craniofacial deformities.

  18. Evaluation of the shape memory performances of poly(ε-caprolactone)-based tubular devices for potential biomedical applications

    Science.gov (United States)

    Pandini, Stefano; Borboni, Alberto; Bodini, Ileana; Vetturi, David; Cambiaghi, Danilo; Paderni, Katia; Messori, Massimo; Toselli, Maurizio; Riccò, Theonis

    2014-05-01

    The shape memory behavior of tubular specimens based on crosslinked poly(ɛ-caprolactone) was investigated in order to evaluate their ability i) to restore their shape after being folded in a more compact one, and ii) to exert stress under external confinement (recovery stress). The specimens were prepared following different crosslinking methodologies and with different network densities, in order to tailor the material response in terms of transformation temperatures and recovery stress capabilities. The devices are able to fully recover their shape once heated close to the melting temperature and to exert moderate stresses, that may be controlled through thickness and crosslink density, and whose values were employed to develop a new testing apparatus for the measurement of radial dilation capabilities.

  19. Flexible magnetoimpidence sensor

    KAUST Repository

    Kavaldzhiev, Mincho

    2015-05-01

    Recently, flexible electronic devices have attracted increasing interest, due to the opportunities they promise for new applications such as wearable devices, where the components are required to flex during normal use[1]. In this light, different magnetic sensors, like microcoil, spin valve, giant magnetoresistance (GMR), magnetoimpedance (MI), have been studied previously on flexible substrates.

  20. Electromagnetic induction heating of an orthopaedic nickel--titanium shape memory device.

    Science.gov (United States)

    Müller, Christian W; Pfeifer, Ronny; El-Kashef, Tarek; Hurschler, Christof; Herzog, Dirk; Oszwald, Markus; Haasper, Carl; Krettek, Christian; Gösling, Thomas

    2010-12-01

    Shape memory orthopaedic implants made from nickel-titanium (NiTi) might allow the modulation of fracture healing, changing their cross-sectional shape by employing the shape memory effect. We aimed to show the feasibility and safety of contact-free electromagnetic induction heating of NiTi implants in a rat model. A water-cooled generator-oscillator combination was used. Induction characteristics were determined by measuring the temperature increase of a test sample in correlation to generator power and time. In 53 rats, NiTi implants were introduced into the right hind leg. The animals were transferred to the inductor, and the implant was electromagnetically heated to temperatures between 40 and 60°C. Blood samples were drawn before and 4 h after the procedure. IL-1, IL-4, IL-10, TNF-α, and IFN-γ were measured. Animals were euthanized at 3 weeks. Histological specimens from the hind leg and liver were retrieved and examined for inflammatory changes, necrosis, and corrosion pits. Cytokine measurements and histological specimens showed no significant differences among the groups. We concluded that electromagnetic induction heating of orthopedic NiTi implants is feasible and safe in a rat model. This is the first step in the development of new orthopedic implants in which stiffness or rigidity can be modified after implantation to optimize bone-healing.

  1. A Survey of Surface Modification Techniques for Next-Generation Shape Memory Polymer Stent Devices

    Directory of Open Access Journals (Sweden)

    Tina Govindarajan

    2014-08-01

    Full Text Available The search for a single material with ideal surface properties and necessary mechanical properties is on-going, especially with regard to cardiovascular stent materials. Since the majority of stent problems arise from surface issues rather than bulk material deficiencies, surface optimization of a material that already contains the necessary bulk properties is an active area of research. Polymers can be surface-modified using a variety of methods to increase hemocompatibilty by reducing either late-stage restenosis or acute thrombogenicity, or both. These modification methods can be extended to shape memory polymers (SMPs, in an effort to make these materials more surface compatible, based on the application. This review focuses on the role of surface modification of materials, mainly polymers, to improve the hemocompatibility of stent materials; additional discussion of other materials commonly used in stents is also provided. Although shape memory polymers are not yet extensively used for stents, they offer numerous benefits that may make them good candidates for next-generation stents. Surface modification techniques discussed here include roughening, patterning, chemical modification, and surface modification for biomolecule and drug delivery.

  2. Mechanical properties of amorphous indium–gallium–zinc oxide thin films on compliant substrates for flexible optoelectronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, D.W., E-mail: DWM172@bham.ac.uk [University of Birmingham, School of Metallurgy and Materials, Edgbaston, Birmingham, B15 2TT (United Kingdom); Waddingham, R.; Flewitt, A.J. [University of Cambridge, Electrical Engineering Division, Department of Engineering, J J Thomson Avenue, Cambridge CB3 0FA,United Kingdom (United Kingdom); Sierros, K.A. [West Virginia University, Mechanical & Aerospace Engineering, Morgantown, WV 26506 (United States); Bowen, J. [Open University, Department of Engineering and Innovation, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Kukureka, S.N. [University of Birmingham, School of Metallurgy and Materials, Edgbaston, Birmingham, B15 2TT (United Kingdom)

    2015-11-02

    Amorphous indium–gallium–zinc-oxide (a-IGZO) thin films were deposited using RF magnetron sputtering on polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) flexible substrates and their mechanical flexibility investigated using uniaxial tensile and buckling tests coupled with in situ optical microscopy. The uniaxial fragmentation test demonstrated that the crack onset strain of the IGZO/PEN was ~ 2.9%, which is slightly higher than that of IGZO/PET. Also, uniaxial tensile crack density analysis suggests that the saturated crack spacing of the film is strongly dependent on the mechanical properties of the underlying polymer substrate. Buckling test results suggest that the crack onset strain (equal to ~ 1.2%, of the IGZO/polymer samples flexed in compression to ~ 5.7 mm concave radius of curvature) is higher than that of the samples flexed with the film being in tension (convex bending) regardless whether the substrate is PEN or PET. The saturated crack density of a-IGZO film under the compression buckling mode is smaller than that of the film under the tensile buckling mode. This could be attributed to the fact that the tensile stress encouraged this crack formation originating from surface defects in the coating. It could also be due to the buckling delamination of the thin coating from the substrate at a lower strain than that at which a crack initiates during flexing in compression. These results provide useful information on the mechanical reliability of a-IGZO films for the development of flexible electronics. - Highlights: • Mechanical flexibility of IGZO thin films investigated by uniaxial tensile and buckling tests • Uniaxial fragmentation gives crack onset strain for IGZO/PEN of 2.9% (higher than for IGZO/PET.) • Saturated crack spacing strongly dependent on mechanical properties of polymer substrate • Crack onset strain in concave bending higher than in convex bending for both substrates.

  3. Flexible, Transparent, Thickness-Controllable SWCNT/PEDOT:PSS Hybrid Films Based on Coffee-Ring Lithography for Functional Noncontact Sensing Device

    KAUST Repository

    Tai, Yanlong

    2015-12-08

    Flexible transparent conductive films (FTCFs) as the essential components of the next generation of functional circuits and devices are presently attracting more attention. Here, a new strategy has been demonstrated to fabricate thickness-controllable FTCFs through coffee ring lithography (CRL) of single-wall carbon nanotube (SWCNT)/poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate (PEDOT:PSS) hybrid ink. The influence of ink concentration and volume on the thickness and size of hybrid film has been investigated systematically. Results show that the final FTCFs present a high performance, including a homogeneous thickness of 60-65 nm, a sheet resistance of 1.8 kohm/sq, a visible/infrared-range transmittance (79%, PET = 90%), and a dynamic mechanical property (>1000 cycle, much better than ITO film), respectively, when SWCNT concentration is 0.2 mg/mL, ink volume is 0.4 μL, drying at room temperature. Moreover, the benefits of these kinds of FTCFs have been verified through a full transparent, flexible noncontact sensing panel (3 × 4 sensing pixels) and a flexible battery-free wireless sensor based on a humidity sensing mechanism, showing excellent human/machine interaction with high sensitivity, good stability, and fast response/recovery ability. © 2015 American Chemical Society.

  4. Dielectric elastomer memory

    Science.gov (United States)

    O'Brien, Benjamin M.; McKay, Thomas G.; Xie, Sheng Q.; Calius, Emilio P.; Anderson, Iain A.

    2011-04-01

    Life shows us that the distribution of intelligence throughout flexible muscular networks is a highly successful solution to a wide range of challenges, for example: human hearts, octopi, or even starfish. Recreating this success in engineered systems requires soft actuator technologies with embedded sensing and intelligence. Dielectric Elastomer Actuator(s) (DEA) are promising due to their large stresses and strains, as well as quiet flexible multimodal operation. Recently dielectric elastomer devices were presented with built in sensor, driver, and logic capability enabled by a new concept called the Dielectric Elastomer Switch(es) (DES). DES use electrode piezoresistivity to control the charge on DEA and enable the distribution of intelligence throughout a DEA device. In this paper we advance the capabilities of DES further to form volatile memory elements. A set reset flip-flop with inverted reset line was developed based on DES and DEA. With a 3200V supply the flip-flop behaved appropriately and demonstrated the creation of dielectric elastomer memory capable of changing state in response to 1 second long set and reset pulses. This memory opens up applications such as oscillator, de-bounce, timing, and sequential logic circuits; all of which could be distributed throughout biomimetic actuator arrays. Future work will include miniaturisation to improve response speed, implementation into more complex circuits, and investigation of longer lasting and more sensitive switching materials.

  5. Double-Twisted Conductive Smart Threads Comprising a Homogeneously and a Gradient-Coated Thread for Multidimensional Flexible Pressure-Sensing Devices

    KAUST Repository

    Tai, Yanlong

    2016-03-17

    Fiber-based, flexible pressure-sensing systems have attracted attention recently due to their promising application as electronic skins. Here, a new kind of flexible pressure-sensing device based on a polydimethylsiloxane membrane instrumented with double-twisted smart threads (DTSTs) is reported. DTSTs are made of two conductive threads obtained by coating cotton threads with carbon nanotubes. One thread is coated with a homogeneous thickness of single-walled carbon nanotubes (SWCNTs) to detect the intensity of an applied load and the other is coated with a graded thickness of SWCNTs to identify the position of the load along the thread. The mechanism and capacity of DTSTs to accurately sense an applied load are systematically analyzed. Results demonstrate that the fabricated 1D, 2D, and 3D sensing devices can be used to predict both the intensity and the position of an applied load. The sensors feature high sensitivity (between ≈0.1% and 1.56% kPa) and tunable resolution, good cycling resilience (>104 cycles), and a short response time (minimum 2.5 Hz). The presented strategy is a viable alternative for the design of simple, low-cost pressure sensors.

  6. Comparative experiments of graphene covalently and physically binding CdSe quantum dots to enhance the electron transport in flexible photovoltaic devices.

    Science.gov (United States)

    Jung, Mi-Hee; Chu, Moo-Jung

    2014-08-07

    In this research, we prepared composite films via covalent coupling of CdSe quantum dots (QDs) to graphene through the direct binding of aryl radicals to the graphene surface. To compare the carrier transport with the CdSe aryl binding graphene film, we prepared CdSe pyridine capping graphene films through the pi-pi interactions of noncovalent bonds between the graphene and pyridine molecules. The photovoltaic devices were fabricated from the two hybrid films using the electrophoretic deposition method on flexible substrates. Even though the two hybrid films have the same amount of QDs and graphene, time-resolved fluorescence emission decay results show that the emission lifetime of the CdSe aryl group binding graphene film is significantly shorter than that of the pyridine capping CdSe-graphene. The quantum efficiency and photocurrent density of the device fabricated from CdSe aryl binding graphene were also higher than those of the device fabricated from pyridine capping CdSe-graphene. These results indicated that the carrier transport of the QD-graphene system is not related to the additive effect from the CdSe and graphene components but rather is a result of the unique interactions between the graphene and QDs. We could expect that these results can be useful in designing QD-graphene composite materials, which are applied in photovoltaic devices.

  7. Reactive Ion Etching as Cleaning Method Post Chemical Mechanical Polishing for Phase Change Memory Device

    Institute of Scientific and Technical Information of China (English)

    ZHONG Min; SONG Zhi-Tang; LIU Bo; FENG Song-Lin; CHEN Bomy

    2008-01-01

    In order to improve nano-scale phase change memory performance,a super-clean interface should be obtained after chemical mechanical polishing (CMP) of Ge2Sb2Te5 phase change films.We use reactive ion etching (RIE) as the cleaning method.The cleaning effect is analysed by scanning electron microscopy and an energy dispersive spectrometer.The results show that particle residue on the surface has been removed.Meanwhile,Ge2 Sb2 Te5 material stoichiometric content ratios are unchanged.After the top electrode is deposited,currentvoltage characteristics test demonstrates that the set threshold voltage is reduced from 13 V to 2.7V and the threshold current from 0.1 mA to 0.025 mA.Furthermore,we analyse the RIE cleaning principle and compare it with the ultrasonic method.

  8. Low-temperature LPCVD of Si nanocrystals from disilane and trisilane (Silcore®) embedded in ALD-alumina for non-volatile memory devices

    NARCIS (Netherlands)

    Brunets, I.; Aarnink, A.A.I.; Boogaard, A.; Kovalgin, A.Y.; Wolters, R.A.M.; Holleman, J.; Schmitz, J.

    2007-01-01

    Non-volatile memory devices are realized using CVD and ALD of all active layers in a cluster tool. The floating gate consists of silicon nanocrystals. A high nanocrystal density was obtained through an enhanced nucleation rate by using disilane (Si2H6) as well as trisilane (Si3H8, known as Silcore®)

  9. Rare-Earth Ions in Niobium-Based Devices as a Quantum Memory: Magneto-Optical Effects on Room Temperature Electrical Transport

    Science.gov (United States)

    2016-09-01

    University of Delaware , Newark, DE. 5f. WORK UNIT NUMBER REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-01-0188 The public reporting burden for...ANSI Std . Z39.18 September 2016 Final Rare-Earth Ions in Niobium-based Devices as a Quantum Memory Magneto-Optical Effects on Room Temperature

  10. A memory efficient implementation scheme of Gauss error function in a Laguerre-Volterra network for neuroprosthetic devices.

    Science.gov (United States)

    Li, Will X Y; Cui, Ke; Zhang, Wei

    2017-04-01

    Cognitive neural prosthesis is a manmade device which can be used to restore or compensate for lost human cognitive modalities. The generalized Laguerre-Volterra (GLV) network serves as a robust mathematical underpinning for the development of such prosthetic instrument. In this paper, a hardware implementation scheme of Gauss error function for the GLV network targeting reconfigurable platforms is reported. Numerical approximations are formulated which transform the computation of nonelementary function into combinational operations of elementary functions, and memory-intensive look-up table (LUT) based approaches can therefore be circumvented. The computational precision can be made adjustable with the utilization of an error compensation scheme, which is proposed based on the experimental observation of the mathematical characteristics of the error trajectory. The precision can be further customizable by exploiting the run-time characteristics of the reconfigurable system. Compared to the polynomial expansion based implementation scheme, the utilization of slice LUTs, occupied slices, and DSP48E1s on a Xilinx XC6VLX240T field-programmable gate array has decreased by 94.2%, 94.1%, and 90.0%, respectively. While compared to the look-up table based scheme, 1.0×10(17) bits of storage can be spared under the maximum allowable error of 1.0×10(-3). The proposed implementation scheme can be employed in the study of large-scale neural ensemble activity and in the design and development of neural prosthetic device.

  11. Application of NiMoNb adhesion layer on plasma-treated polyimide substrate for flexible electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Bang, S.-H.; Kim, K.-K.; Jung, H.-Y.; Kim, T.-H.; Jeon, S.-H. [Metal and Material Technology Group, R and D Center, LS Mtron Ltd., Gyeonggi 431-080 (Korea, Republic of); Seol, Jae-Bok, E-mail: zptkfm20@hanmail.net [Max-Planck-Insititut für Eisenforschung, Max-Planck-Str. 1, D-40237 Düsseldorf (Germany)

    2014-05-02

    A thin film, NiMoNb, was introduced as an adhesion layer between the Cu metal and the insulator polyimide substrate in a flexible Cu-clad laminated structure. Using 90° peel test, we evaluated the peel strength of the system as a function of the thickness of the adhesion layer. An increase in the NiMoNb thickness from 7 to 40 nm enhanced the peel strength of the deposited systems. After plasma treatment by the roll-to-roll method, the multilayer structure showed an outstanding peel strength of ∼ 529 N/m, even after thermal annealing at 150 °C for 168 h. We also studied the role of plasma treatment of the polyimide substrate on the adhesion strength and microstructure of a flexible Cu-clad laminated structure by peel strength, atomic force microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. These experimental observations showed that the plasma-treated polyimide substrate with the deposition of NiMoNb showed the enhanced adhesion of ∼ 656 N/m, because of the change of functional groups, which affected the bonding force and crystallinity of the thin films deposited on polyimide, rather than an increase in the surface roughness. - Highlights: • NiMoNb film on polyimide substrate was employed for higher peel strength. • Plasma-treated substrate enhances the peel strength of multilayer. • Even when annealed at 150 °C, plasma-treated films showed enhanced peel strength.

  12. Progress of alternative sintering approaches of inkjet-printed metal inks and their application for manufacturing of flexible electronic devices

    NARCIS (Netherlands)

    Wünscher, S.; Abbel, R.; Perelaer, J.; Schubert, U.S.

    2014-01-01

    Well-defined high resolution structures with excellent electrical conductivities are key components of almost every electronic device. Producing these by printing metal based conductive inks on polymer foils represents an important step forward towards the manufacturing of plastic electronic product

  13. Preserving color fidelity for display devices using scalable memory compression architecture for text, graphics, and video

    Science.gov (United States)

    Lebowsky, Fritz; Nicolas, Marina

    2014-01-01

    High-end monitors and TVs based on LCD technology continue to increase their native display resolution to 4k by 2k and beyond. Subsequently, uncompressed pixel amplitude processing becomes costly not only when transmitting over cable or wireless communication channels, but also when processing with array processor architectures. For motion video content, spatial preprocessing from YCbCr 444 to YCbCr 420 is widely accepted. However, due to spatial low pass filtering in horizontal and vertical direction, quality and readability of small text and graphics content is heavily compromised when color contrast is high in chrominance channels. On the other hand, straight forward YCbCr 444 compression based on mathematical error coding schemes quite often lacks optimal adaptation to visually significant image content. We present a block-based memory compression architecture for text, graphics, and video enabling multidimensional error minimization with context sensitive control of visually noticeable artifacts. As a result of analyzing image context locally, the number of operations per pixel can be significantly reduced, especially when implemented on array processor architectures. A comparative analysis based on some competitive solutions highlights the effectiveness of our approach, identifies its current limitations with regard to high quality color rendering, and illustrates remaining visual artifacts.

  14. 21 CFR 874.4710 - Esophagoscope (flexible or rigid) and accessories.

    Science.gov (United States)

    2010-04-01

    ... generic type of device includes the flexible foreign body claw, flexible biopsy forceps, rigid biopsy curette, flexible biopsy brush, rigid biopsy forceps and flexible biopsy curette, but excludes...

  15. Enhancement of Power Quality in Transmission Line Using Flexible Ac Transmission System Device U.P.F.C (Unified Power Flow Controller

    Directory of Open Access Journals (Sweden)

    B. Divya Lakshmi

    2014-04-01

    Full Text Available Present scenario states that power demand has been increased in a rapid and random manner. Hence power generated is unable to meet the power demand so power scarcity exists. There is an approximate loss of (20 - 40 % of power generated during its transmission. Hence there is a need for enhancing the power quality in transmission lines. In order to improve the power quality our paper make use of FACTS DEVICES. FACTS devices can be added to power transmission and distribution systems at appropriate locations to improve system performance. The real and reactive powers can be easily controlled in a power system with FACTS devices. Flexible AC Transmission System creates a tremendous quality impact on power system stability. This paper describes the basic principle of operation of UPFC, its advantages and to compare its performance with the various FACTS equipment available. The objective of this paper is to keep the power system to remain in voltage stable condition when it experiences a load change and contingency, also deals with the simulation of various FACTS controllers using simulation program with MATLAB/SIMULINK

  16. Multiferroic domain boundaries as active memory devices: trajectories towards domain boundary engineering.

    Science.gov (United States)

    Salje, Ekhard K H

    2010-04-06

    Twin boundaries in ferroelastics and curved interfaces between crystalline and amorphous zircon can, in principle, act as multiferroic structural elements and lead the way to the discovery of novel multiferroic devices which are based on structurally heterogeneous materials. While this paradigm has not yet been explored in full, this review shows that physical and chemical properties can vary dramatically inside twin boundaries and interfaces. Properties that have been already been explored include electric dipoles in a non-polar matrix, the appearance of superconductivity in twin boundaries and the catalytic reaction of hydrous species in interfaces of radiation damaged material. Some of the fundamental physical and chemical properties of twin boundaries and related interfaces are described and possible applications are outlined.

  17. Fabrication and properties of nanoscale multiferroic heterostructures for application in magneto-electric random access memory (MERAM) devices

    Science.gov (United States)

    Kim, Gunwoo

    Magnetoelectric random access memory (MERAM) has emerged as a promising new class of non-volatile solid-state memory device. It offers nondestructive reading along with low power consumption during the write operation. A common implementation of MERAM involves use of multiferroic tunneling junctions (MFTJs), which besides offering non-volatility are both electrically and magnetically tunable. Fundamentally, a MFTJ consists of a heterostructure of an ultrathin multiferroic or ferroelectric material as the active tunneling barrier sandwiched between ferromagnetic electrodes. Thereby, the MFTJ exhibits both tunnel electroresistance (TER) and tunnel magnetoresistance (TMR) effects with application of an electric and magnetic field, respectively. In this thesis work, we have developed two-dimensional (2D) thin-film multiferroic heterostructure METJ prototypes consisting of ultrathin ferroelectric BaTiO3 (BTO) layer and a conducting ferromagnetic La0.67Sr 0.33MnO3 (LSMO) electrode. The heteroepitaxial films are grown using the pulsed laser deposition (PLD) technique. This oxide heterostructure offers the opportunity to study the nano-scale details of the tunnel electroresistance (TER) effect using scanning probe microscopy techniques. We performed the measurements using the MFP-3D (Asylum Research) scanning probe microscope. The ultrathin BTO films (1.2-2.0 nm) grown on LSMO electrodes display both ferro- and piezo-electric properties and exhibit large tunnel resistance effect. We have explored the growth and properties of one-dimensional (1D) heterostructures, referred to as multiferoric nanowire (NW) heterostructures. The ferromagnetic/ferroelectric composite heterostructures are grown as sheath layers using PLD on lattice-matched template NWs, e.g. MgO, that are deposited by chemical vapor deposition utilizing the vapor-liquid-solid (VLS) mechanism. The one-dimensional geometry can substantially overcome the clamping effect of the substrate present in two

  18. Optimization of poly(vinylidene fluoride-trifluoroethylene) films as non-volatile memory for flexible electronics

    KAUST Repository

    Mao, Duo

    2010-05-01

    The impact of thermal treatment and thickness on the polarization and leakage current of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer thin film capacitors has been studied. The evolution of the film morphology, crystallinity and bonding orientation as a function of annealing temperature and thickness were characterized using multiple techniques. Electrical performance of the devices was correlated with the material properties. It was found that annealing at or slightly above the Curie temperature (Tc) is the optimal temperature for high polarization, smooth surface morphology and low leakage current. Higher annealing temperature (but below the melting temperature Tm) favors larger size β crystallites through molecular chain self-organization, resulting in increased film roughness, and the vertical polarization tends to saturate. Metal-Ferroelectric-Metal (MFM) capacitors consistently achieved Ps, Pr and Vc of 8.5 μC/cm2, 7.4 μC/cm2 and 10.2 V, respectively.

  19. Graphene-graphene oxide floating gate transistor memory.

    Science.gov (United States)

    Jang, Sukjae; Hwang, Euyheon; Lee, Jung Heon; Park, Ho Seok; Cho, Jeong Ho

    2015-01-21

    A novel transparent, flexible, graphene channel floating-gate transistor memory (FGTM) device is fabricated using a graphene oxide (GO) charge trapping layer on a plastic substrate. The GO layer, which bears ammonium groups (NH3+), is prepared at the interface between the crosslinked PVP (cPVP) tunneling dielectric and the Al2 O3 blocking dielectric layers. Important design rules are proposed for a high-performance graphene memory device: (i) precise doping of the graphene channel, and (ii) chemical functionalization of the GO charge trapping layer. How to control memory characteristics by graphene doping is systematically explained, and the optimal conditions for the best performance of the memory devices are found. Note that precise control over the doping of the graphene channel maximizes the conductance difference at a zero gate voltage, which reduces the device power consumption. The proposed optimization via graphene doping can be applied to any graphene channel transistor-type memory device. Additionally, the positively charged GO (GO-NH3+) interacts electrostatically with hydroxyl groups of both UV-treated Al2 O3 and PVP layers, which enhances the interfacial adhesion, and thus the mechanical stability of the device during bending. The resulting graphene-graphene oxide FGTMs exhibit excellent memory characteristics, including a large memory window (11.7 V), fast switching speed (1 μs), cyclic endurance (200 cycles), stable retention (10(5) s), and good mechanical stability (1000 cycles).

  20. A bio-enabled maximally mild layer-by-layer Kapton surface modification approach for the fabrication of all-inkjet-printed flexible electronic devices

    Science.gov (United States)

    Fang, Yunnan; Hester, Jimmy G. D.; Su, Wenjing; Chow, Justin H.; Sitaraman, Suresh K.; Tentzeris, Manos M.

    2016-12-01

    A bio-enabled, environmentally-friendly, and maximally mild layer-by-layer approach has been developed to surface modify inherently hydrophobic Kapton HN substrates to allow for great printability of both water- and organic solvent-based inks thus facilitating the full-inkjet-printing of flexible electronic devices. Different from the traditional Kapton surface modification approaches which are structure-compromising and use harsh conditions to target, and oxidize and/or remove part of, the surface polyimide of Kapton, the present Kapton surface modification approach targeted the surface electric charges borne by its additive particles, and was not only the first to utilize environmentally-friendly clinical biomolecules to build up a thin film of protamine-heparin complex on Kapton, but also the first to be conducted under minimally destructive and maximally mild conditions. Besides, for electrically charged ink particles, the present surface modification method can enhance the uniformity of the inkjet-printed films by reducing the “coffee ring effect”. As a proof-of-concept demonstration, reduced graphene oxide-based gas sensors, which were flexible, ultra-lightweight, and miniature-sized, were fully-inkjet-printed on surface modified Kapton HN films and tested for their sensitivity to dimethyl methylphosphonate (a nerve agent simulant). Such fabricated sensors survived a Scotch-tape peel test and were found insensitive to repeated bending to a small 0.5 cm radius.

  1. Charge storage properties of InP quantum dots in GaAs metal-oxide-semiconductor based nonvolatile flash memory devices

    Science.gov (United States)

    Kundu, Souvik; Halder, Nripendra N.; Biswas, Pranab; Biswas, D.; Banerji, P.; Mukherjee, Rabibrata; Chakraborty, S.

    2012-11-01

    Metal organic vapor phase epitaxially grown 5 nm InP quantum dots (QDs) were embedded as charge storage elements between high-k control and tunneling dielectric layers in GaAs metal-oxide-semiconductor based nonvolatile memory devices. The QDs trap more electrons resulting in a large memory window (6.3 V) along with low leakage due to Coulomb blockade effect. 16.5% charge loss was found even after 105 s indicating its good charge storing potential. The programming and erasing operations were discussed with proposed band diagram.

  2. CMOS compatible fabrication of flexible and semi-transparent FeRAM on ultra-thin bulk monocrystalline silicon (100) fabric

    KAUST Repository

    Ghoneim, Mohamed T.

    2014-08-01

    Commercialization of flexible electronics requires reliable, high performance, ultra-compact and low power devices. To achieve them, we fabricate traditional electronics on bulk mono-crystalline silicon (100) and transform the top portion into an ultra-thin flexible silicon fabric with prefabricated devices, preserving ultra-large-scale-integration density and same device performance. This can be done in a cost effective manner due to its full compatibility with standard CMOS processes. In this paper, using the same approach, for the first time we demonstrate a ferroelectric random access memory (FeRAM) cell on flexible silicon fabric platform and assess its functionality and practical potential.

  3. Effect of annealing treatment on the electrical characteristics of Pt/Cr-embedded ZnO/Pt resistance random access memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Li-Chun, E-mail: lcchang@mail.mcut.edu.tw [Department of Materials Engineering, Ming Chi University of Technology, No. 84, Gongzhuan Rd., Taishan Dist., New Taipei City 24301, Taiwan and Center for Thin Film Technologies and Applications, Ming Chi University of Technology, No. 84, Gongzhuan Rd., Taishan Dist., New Taipei City 24301, Taiwan (China); Kao, Hsuan-Ling [Department of Electronic Engineering, Chang Gung University, No. 259, Wen-Hwa 1st Rd., Kwei-Shan Tao-Yuan 33302, Taiwan (China); Liu, Keng-Hao [Department of Electronic Engineering, Chang Gung University, Tao-Yuan, Taiwan (China)

    2014-03-15

    ZnO/Cr/ZnO trilayer films sandwiched with Pt electrodes were prepared for nonvolatile resistive memory applications. The threshold voltage of a ZnO device embedded with a 3-nm Cr interlayer was approximately 50% lower than that of a ZnO monolayer device. This study investigated threshold voltage as a function of Cr thickness. Both the ZnO monolayer device and the Cr-embedded ZnO device structures exhibited resistance switching under electrical bias both before and after rapid thermal annealing (RTA) treatment, but resistive switching effects in the two cases exhibited distinct characteristics. Compared with the as-fabricated device, the memory cell after RTA demonstrated remarkable device parameter improvements, including a lower threshold voltage, a lower write current, and a higher R{sub off}/R{sub on} ratio. Both transmission electron microscope observations and Auger electron spectroscopy revealed that the Cr charge trapping layer in Cr-embedded ZnO dispersed uniformly into the storage medium after RTA, and x-ray diffraction and x-ray photoelectron spectroscopy analyses demonstrated that the Cr atoms lost electrons to become Cr{sup 3+} ions after dispersion. These results indicated that the altered status of Cr in ZnO/Cr/ZnO trilayer films during RTA treatment was responsible for the switching mechanism transition.

  4. GaAs metal-oxide-semiconductor based non-volatile flash memory devices with InAs quantum dots as charge storage nodes

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Sk Masiul, E-mail: masiulelt@gmail.com; Chowdhury, Sisir; Sarkar, Krishnendu; Nagabhushan, B.; Banerji, P. [Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302 (India); Chakraborty, S. [Applied Materials Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Sector-I, Kolkata 700 064 (India); Mukherjee, Rabibrata [Department of Chemical Engineering, Indian Institute of Technology, Kharagpur 721302 (India)

    2015-06-24

    Ultra-thin InP passivated GaAs metal-oxide-semiconductor based non-volatile flash memory devices were fabricated using InAs quantum dots (QDs) as charge storing elements by metal organic chemical vapor deposition technique to study the efficacy of the QDs as charge storage elements. The grown QDs were embedded between two high-k dielectric such as HfO{sub 2} and ZrO{sub 2}, which were used for tunneling and control oxide layers, respectively. The size and density of the QDs were found to be 5 nm and 1.8×10{sup 11} cm{sup −2}, respectively. The device with a structure Metal/ZrO{sub 2}/InAs QDs/HfO{sub 2}/GaAs/Metal shows maximum memory window equivalent to 6.87 V. The device also exhibits low leakage current density of the order of 10{sup −6} A/cm{sup 2} and reasonably good charge retention characteristics. The low value of leakage current in the fabricated memory device is attributed to the Coulomb blockade effect influenced by quantum confinement as well as reduction of interface trap states by ultra-thin InP passivation on GaAs prior to HfO{sub 2} deposition.

  5. Demo-application of shape memory alloy devices: the rehabilitation of the S. Giorgio Church bell tower

    Science.gov (United States)

    Indirli, Maurizio; Castellano, Maria G.; Clemente, Paolo; Martelli, Alessandro

    2001-07-01

    This paper describes the rehabilitation of the S. Giorgio Church Bell-Tower (Trignano, Municipality of S. Martino in Rio, Reggio Emilia, Italy), completed in September 1999. This masonry building, seriously damaged by the earthquake of October 15th 1996 which struck the Reggio Emilia and Modena Districts, Italy), was investigated by the authors immediately after the seismic event, as other ancient Cultural Heritage Structures (CUHESs) in the same area. In the past, seismic events have visited substantial destruction that translates into a significant loss of architectural heritage. The most common solution traditionally used to enhance the CUHESs seismic behaviour is the introduction of localized reinforcements, usually Traditional Steel Ties (TSTs), increasing stability and ductility. Anyway, in many cases said reinforcement techniques, often too invasive, proved to be inadequate to prevent collapse. For these reasons, the Bell-Tower intervention applies Innovative Antiseismic Techniques (IATs) by the use of superelastic Shape Memory Alloy (SMA) Devices (SMADs), a technology developed after a large amount of theoretical studies, numerical analyses and test campaigns. The SMADs, which can be considered a powerful tool with respect to the traditional methods, provide acceleration reduction, force limitation and energy dissipation. Furthermore, they are characterized by low invasivity and complete reversibility. When another earthquake occurred on June 18th 2000, with the same epicenter and a comparable Richter Magnitudo, the Bell-Tower, subjected to a new investigation, showed no damage of any type. Thus, the new seismic event has been the best verification of the retrofit intervention.

  6. Use of the asymmetric planar hall resistance of an Fe film for possible multi-value memory device applications.

    Science.gov (United States)

    Yoo, Taehee; Khym, S; Lee, Hakjoon; Lee, Sangyeop; Kim, Shinhee; Shin, Jinsik; Lee, Sanghoon; Liu, X; Furdyna, J K

    2011-07-01

    Systematic planar Hall measurements have been performed on a ferromagnetic Fe film grown on a standard (001) GaAs substrate at room temperature. The angular dependence of the planar Hall effect revealed the presence of both four-fold (cubic) and two-fold (uniaxial) anisotropies in the 7 nm thick Fe film. The dominance of the four-fold symmetric anisotropy, however, provided four magnetic easy axes near the (100) direction, which results in a two step switching phenomenon in the magnetization reversal process. An interesting asymmetric hysteresis loop was observed in the planar Hall resistance (PHR) when the turning point of the field scan is set at the value in the region of the second transition. The intermediate resistance states appearing in the asymmetric PHR loop were understood in terms of mutli-domain structures formed during the second switching of magnetization. Such multi-domain structure of the Fe film showing robust time stability provided additional Hall resistance states, which can be used for multi-valued memory device applications.

  7. Computational models for the determination of depth-dependent mechanical properties of skin with a soft, flexible measurement device

    Science.gov (United States)

    Yuan, Jianghong; Dagdeviren, Canan; Shi, Yan; Ma, Yinji; Feng, Xue; Rogers, John A.; Huang, Yonggang

    2016-10-01

    Conformal modulus sensors (CMS) incorporate PZT nanoribbons as mechanical actuators and sensors to achieve reversible conformal contact with the human skin for non-invasive, in vivo measurements of skin modulus. An analytic model presented in this paper yields expressions that connect the sensor output voltage to the Young moduli of the epidermis and dermis, the thickness of the epidermis, as well as the material and geometrical parameters of the CMS device itself and its encapsulation layer. Results from the model agree well with in vitro experiments on bilayer structures of poly(dimethylsiloxane). These results provide a means to determine the skin moduli (epidermis and dermis) and the thickness of the epidermis from in vivo measurements of human skin.

  8. Coordination of Series and Shunt Flexible Alternating Current Transmission Line System Devices Based Thyristor Controller for Improving Power System Stability

    Directory of Open Access Journals (Sweden)

    Prechanon Kumkratug

    2011-01-01

    Full Text Available Problem statement: Thyristor Controlled Series Capacitor (TCSC and Static Var Compensator (SVC have been individually applied to improve stability of power system. Approach: This study presents the coordination of a TCSC and SVC for improving power system stability. The swing curves of the three phase faulted power system with various cases are tested and compared. Results: The swing curve of system without FACTS devices has undamped oscillation. The system with a TCSC or a SVC can increase damping of power system whereas the system with coordination of a TCSC and a SVC provides the best results of stability improvement Conclusion: From the simulation results, the stability of power system can be much better improved by coordination control of a TCSC and a SVC.

  9. Organic nano-floating-gate transistor memory with metal nanoparticles

    Science.gov (United States)

    Van Tho, Luu; Baeg, Kang-Jun; Noh, Yong-Young

    2016-04-01

    Organic non-volatile memory is advanced topics for various soft electronics applications as lightweight, low-cost, flexible, and printable solid-state data storage media. As a key building block, organic field-effect transistors (OFETs) with a nano-floating gate are widely used and promising structures to store digital information stably in a memory cell. Different types of nano-floating-gates and their various synthesis methods have been developed and applied to fabricate nanoparticle-based non-volatile memory devices. In this review, recent advances in the classes of nano-floating-gate OFET memory devices using metal nanoparticles as charge-trapping sites are briefly reviewed. Details of device fabrication, characterization, and operation mechanisms are reported based on recent research activities reported in the literature.

  10. Preferences and flexibility in decision-making among dental clinicians regarding the treatment of multirooted teeth: an interactive communication device-based survey at two academic conferences

    Science.gov (United States)

    2016-01-01

    Purpose Decision-making by dental and medical experts can be influenced by their biases, interests, and experiences, and academic arguments about controversial issues may additionally be considered indirect experiences capable of affecting decision-making. This study reports on the use of interactive communication devices to evaluate preferences and flexibility in decision-making among dental care providers who attended two distinct academic conferences. Methods Two debates were presented by a team of two lecturers at two academic conferences (focusing on periodontology and implant dentistry, respectively) and the audience members of each session were surveyed. Before each lecture, two case modules about the diagnosis and treatment of multirooted molar lesions were provided, and interactive communication devices were used to collect responses about decision-making preferences in treatment planning immediately before and after a debate about treatment strategies. Results In total, 81 and 84 completed answers from both conferences were obtained for the first and second case modules, respectively. The preferred treatment plan differed significantly according to the focus of the conference, and a tendency emerged for the clinicians participating in each conference to express uniform preferences. However, attending the debates resulted in significant changes in decision-making preferences regardless of the conference focus or the characteristics of the participants. Conclusions Our findings suggest that providing continuing education via debates on controversial issues may be effective in widening conceptual knowledge and reducing biases among experts in the dental and medical fields. PMID:27382505

  11. Scalability of carbon-nanotube-based thin film transistors for flexible electronic devices manufactured using an all roll-to-roll gravure printing system

    Science.gov (United States)

    Koo, Hyunmo; Lee, Wookyu; Choi, Younchang; Sun, Junfeng; Bak, Jina; Noh, Jinsoo; Subramanian, Vivek; Azuma, Yasuo; Majima, Yutaka; Cho, Gyoujin

    2015-09-01

    To demonstrate that roll-to-roll (R2R) gravure printing is a suitable advanced manufacturing method for flexible thin film transistor (TFT)-based electronic circuits, three different nanomaterial-based inks (silver nanoparticles, BaTiO3 nanoparticles and single-walled carbon nanotubes (SWNTs)) were selected and optimized to enable the realization of fully printed SWNT-based TFTs (SWNT-TFTs) on 150-m-long rolls of 0.25-m-wide poly(ethylene terephthalate) (PET). SWNT-TFTs with 5 different channel lengths, namely, 30, 80, 130, 180, and 230 μm, were fabricated using a printing speed of 8 m/min. These SWNT-TFTs were characterized, and the obtained electrical parameters were related to major mechanical factors such as web tension, registration accuracy, impression roll pressure and printing speed to determine whether these mechanical factors were the sources of the observed device-to-device variations. By utilizing the electrical parameters from the SWNT-TFTs, a Monte Carlo simulation for a 1-bit adder circuit, as a reference, was conducted to demonstrate that functional circuits with reasonable complexity can indeed be manufactured using R2R gravure printing. The simulation results suggest that circuits with complexity, similar to the full adder circuit, can be printed with a 76% circuit yield if threshold voltage (Vth) variations of less than 30% can be maintained.

  12. In vitro and in vivo evaluation of a shape memory polymer foam-over-wire embolization device delivered in saccular aneurysm models.

    Science.gov (United States)

    Boyle, Anthony J; Landsman, Todd L; Wierzbicki, Mark A; Nash, Landon D; Hwang, Wonjun; Miller, Matthew W; Tuzun, Egemen; Hasan, Sayyeda M; Maitland, Duncan J

    2016-10-01

    Current endovascular therapies for intracranial saccular aneurysms result in high recurrence rates due to poor tissue healing, coil compaction, and aneurysm growth. We propose treatment of saccular aneurysms using shape memory polymer (SMP) foam to improve clinical outcomes. SMP foam-over-wire (FOW) embolization devices were delivered to in vitro and in vivo porcine saccular aneurysm models to evaluate device efficacy, aneurysm occlusion, and acute clotting. FOW devices demonstrated effective delivery and stable implantation in vitro. In vivo porcine aneurysms were successfully occluded using FOW devices with theoretical volume occlusion values greater than 72% and rapid, stable thrombus formation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1407-1415, 2016.

  13. Multilevel charging and discharging mechanisms of nonvolatile memory devices based on nanocomposites consisting of monolayered Au nanoparticles embedded in a polystyrene layer

    Science.gov (United States)

    Yeol Yun, Dong; Hyun Lee, Nam; Seong Kim, Hak; Wook Lee, Sang; Whan Kim, Tae

    2014-01-01

    Capacitance-voltage (C-V) curves for Al/Au nanoparticles embedded in a polystyrene (PS) layer/p-Si devices at 300 K showed a metal-insulator-semiconductor behavior with flat-band voltage shifts of the C-V curves due to the existence of charge trapping. Memory windows between 2.6 and 9.9 V were observed at different sweep voltages, indicative of multilevel behavior. Capacitance-time measurements demonstrated that the charge-trapping capability of Au nanoparticles embedded in a PS layer was maintained for retention times larger than 1 × 104 s without significant degradation. The multilevel charging and discharging mechanisms of the memory devices are described on the basis of the experimental results.

  14. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition

    Science.gov (United States)

    Niu, Gang; Kim, Hee-Dong; Roelofs, Robin; Perez, Eduardo; Schubert, Markus Andreas; Zaumseil, Peter; Costina, Ioan; Wenger, Christian

    2016-06-01

    With the continuous scaling of resistive random access memory (RRAM) devices, in-depth understanding of the physical mechanism and the material issues, particularly by directly studying integrated cells, become more and more important to further improve the device performances. In this work, HfO2-based integrated 1-transistor-1-resistor (1T1R) RRAM devices were processed in a standard 0.25 μm complementary-metal-oxide-semiconductor (CMOS) process line, using a batch atomic layer deposition (ALD) tool, which is particularly designed for mass production. We demonstrate a systematic study on TiN/Ti/HfO2/TiN/Si RRAM devices to correlate key material factors (nano-crystallites and carbon impurities) with the filament type resistive switching (RS) behaviours. The augmentation of the nano-crystallites density in the film increases the forming voltage of devices and its variation. Carbon residues in HfO2 films turn out to be an even more significant factor strongly impacting the RS behaviour. A relatively higher deposition temperature of 300 °C dramatically reduces the residual carbon concentration, thus leading to enhanced RS performances of devices, including lower power consumption, better endurance and higher reliability. Such thorough understanding on physical mechanism of RS and the correlation between material and device performances will facilitate the realization of high density and reliable embedded RRAM devices with low power consumption.

  15. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition.

    Science.gov (United States)

    Niu, Gang; Kim, Hee-Dong; Roelofs, Robin; Perez, Eduardo; Schubert, Markus Andreas; Zaumseil, Peter; Costina, Ioan; Wenger, Christian

    2016-06-17

    With the continuous scaling of resistive random access memory (RRAM) devices, in-depth understanding of the physical mechanism and the material issues, particularly by directly studying integrated cells, become more and more important to further improve the device performances. In this work, HfO2-based integrated 1-transistor-1-resistor (1T1R) RRAM devices were processed in a standard 0.25 μm complementary-metal-oxide-semiconductor (CMOS) process line, using a batch atomic layer deposition (ALD) tool, which is particularly designed for mass production. We demonstrate a systematic study on TiN/Ti/HfO2/TiN/Si RRAM devices to correlate key material factors (nano-crystallites and carbon impurities) with the filament type resistive switching (RS) behaviours. The augmentation of the nano-crystallites density in the film increases the forming voltage of devices and its variation. Carbon residues in HfO2 films turn out to be an even more significant factor strongly impacting the RS behaviour. A relatively higher deposition temperature of 300 °C dramatically reduces the residual carbon concentration, thus leading to enhanced RS performances of devices, including lower power consumption, better endurance and higher reliability. Such thorough understanding on physical mechanism of RS and the correlation between material and device performances will facilitate the realization of high density and reliable embedded RRAM devices with low power consumption.

  16. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition

    Science.gov (United States)

    Niu, Gang; Kim, Hee-Dong; Roelofs, Robin; Perez, Eduardo; Schubert, Markus Andreas; Zaumseil, Peter; Costina, Ioan; Wenger, Christian

    2016-01-01

    With the continuous scaling of resistive random access memory (RRAM) devices, in-depth understanding of the physical mechanism and the material issues, particularly by directly studying integrated cells, become more and more important to further improve the device performances. In this work, HfO2-based integrated 1-transistor-1-resistor (1T1R) RRAM devices were processed in a standard 0.25 μm complementary-metal-oxide-semiconductor (CMOS) process line, using a batch atomic layer deposition (ALD) tool, which is particularly designed for mass production. We demonstrate a systematic study on TiN/Ti/HfO2/TiN/Si RRAM devices to correlate key material factors (nano-crystallites and carbon impurities) with the filament type resistive switching (RS) behaviours. The augmentation of the nano-crystallites density in the film increases the forming voltage of devices and its variation. Carbon residues in HfO2 films turn out to be an even more significant factor strongly impacting the RS behaviour. A relatively higher deposition temperature of 300 °C dramatically reduces the residual carbon concentration, thus leading to enhanced RS performances of devices, including lower power consumption, better endurance and higher reliability. Such thorough understanding on physical mechanism of RS and the correlation between material and device performances will facilitate the realization of high density and reliable embedded RRAM devices with low power consumption. PMID:27312225

  17. Influence of Thermal Annealing Treatment on Bipolar Switching Properties of Vanadium Oxide Thin-Film Resistance Random-Access Memory Devices

    Science.gov (United States)

    Chen, Kai-Huang; Cheng, Chien-Min; Kao, Ming-Cheng; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Wu, Sean; Su, Feng-Yi

    2016-12-01

    The bipolar switching properties and electrical conduction mechanism of vanadium oxide thin-film resistive random-access memory (RRAM) devices obtained using a rapid thermal annealing (RTA) process have been investigated in high-resistive status/low-resistive status (HRS/LRS) and are discussed herein. In addition, the resistance switching properties and quality improvement of the vanadium oxide thin-film RRAM devices were measured by x-ray diffraction (XRD) analysis, x-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and current-voltage (I-V) measurements. The activation energy of the hopping conduction mechanism in the devices was investigated based on Arrhenius plots in HRS and LRS. The hopping conduction distance and activation energy barrier were obtained as 12 nm and 45 meV, respectively. The thermal annealing process is recognized as a candidate method for fabrication of thin-film RRAM devices, being compatible with integrated circuit technology for nonvolatile memory devices.

  18. Influence of Thermal Annealing Treatment on Bipolar Switching Properties of Vanadium Oxide Thin-Film Resistance Random-Access Memory Devices

    Science.gov (United States)

    Chen, Kai-Huang; Cheng, Chien-Min; Kao, Ming-Cheng; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Wu, Sean; Su, Feng-Yi

    2017-04-01

    The bipolar switching properties and electrical conduction mechanism of vanadium oxide thin-film resistive random-access memory (RRAM) devices obtained using a rapid thermal annealing (RTA) process have been investigated in high-resistive status/low-resistive status (HRS/LRS) and are discussed herein. In addition, the resistance switching properties and quality improvement of the vanadium oxide thin-film RRAM devices were measured by x-ray diffraction (XRD) analysis, x-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and current-voltage ( I- V) measurements. The activation energy of the hopping conduction mechanism in the devices was investigated based on Arrhenius plots in HRS and LRS. The hopping conduction distance and activation energy barrier were obtained as 12 nm and 45 meV, respectively. The thermal annealing process is recognized as a candidate method for fabrication of thin-film RRAM devices, being compatible with integrated circuit technology for nonvolatile memory devices.

  19. A simple device unit consisting of all NiO storage and switch elements for multilevel terabit nonvolatile random access memory.

    Science.gov (United States)

    Lee, Myoung-Jae; Ahn, Seung-Eon; Lee, Chang Bum; Kim, Chang-Jung; Jeon, Sanghun; Chung, U-In; Yoo, In-Kyeong; Park, Gyeong-Su; Han, Seungwu; Hwang, In Rok; Park, Bae-Ho

    2011-11-01

    Present charge-based silicon memories are unlikely to reach terabit densities because of scaling limits. As the feature size of memory shrinks to just tens of nanometers, there is insufficient volume available to store charge. Also, process temperatures higher than 800 °C make silicon incompatible with three-dimensional (3D) stacking structures. Here we present a device unit consisting of all NiO storage and switch elements for multilevel terabit nonvolatile random access memory using resistance switching. It is demonstrated that NiO films are scalable to around 30 nm and compatible with multilevel cell technology. The device unit can be a building block for 3D stacking structure because of its simple structure and constituent, high performance, and process temperature lower than 300 °C. Memory resistance switching of NiO storage element is accompanied by an increase in density of grain boundary while threshold resistance switching of NiO switch element is controlled by current flowing through NiO film.

  20. Collaborative Research and Development by EpiSolar and NREL of Processes and Materials for Flexible CdS/CdTe Superstrate Devices: Cooperative Research and Development Final Report, CRADA Number CRD-14-550

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, Teresa [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-05-01

    The objective of this work is to collaborate with EpiSolar to develop and test processes that are consistent with the goals and milestones of an NREL FPace1 (Foundational Program to Advance Cell Efficiency) project entitled 'High-Temperature, Roll-to-Roll (RTR) CdTe Superstrate Devices Using Flexible Glass.' The primary milestone for this CRADA relates to demonstration of a 15% efficient laboratory device.