WorldWideScience

Sample records for cantilever bridges

  1. Integrated optical sensors using micromechanical bridges and cantilevers

    Science.gov (United States)

    Wu, Shaodong; Frankena, Hans J.

    1993-03-01

    Micromechanical bridges and cantilevers sensitive to external forces have been fabricated upon Si substrates. They are used as optical waveguides and part of sensor circuits. The waveguides consist of sandwiched layers of an SiO2 buffer, an Al2O3 waveguide and an SiO2 cover. The bridges and cantilevers with very small dimensions such as 100 micrometers in length, 5 micrometers in width and 2.5 micrometers in thickness have been successfully produced. Such bridge- or cantilever-shaped waveguide structures have been applied in acoustic signal detection and noise monitoring. In this paper, the bridge and cantilever structures will be analyzed and experimental results on sound measurement will be presented.

  2. SEISMIC SAFETY OF THE PRECAST BALCONY CANTILEVER ELEMENTS FOR PREVENTION OF THERMAL BRIDGES

    Directory of Open Access Journals (Sweden)

    Boris Azinović

    2014-12-01

    Full Text Available In the paper the seismic response of precast balcony cantilever structural elements for prevention of thermal bridges was analysed. This solution has been developed in seismic non-prone areas with the main purpose of eliminating a thermal bridge at the point where the balcony is fixed to the building. The solution has been specially made to withstand vertical static loading, not accounting for eventual vertical seismic loads in the case of transferring the solution to more active seismic zones. This paper deals with the seismic analysis of existent precast cantilever elements exposed to vertical accelerations and has proven that some elements in the case of lifting are not sufficient from the safety point of view. The results of the main research results obtained by numerous seismic analyses can be summarized as follows: 1 the insertion of a precast load-bearing thermal insulation element increases the flexibility of RC fixed base cantilevers and therefore limits their length to 300–400 cm, 2 vertical seismic loads can result in the cantilever uplift, which means that tensile stresses could appear also at the bottom of the cross-section 3 precast elements, that appear on the Slovenian market to this day, do not have the appropriate steel reinforcement in the bottom part of the cross-section. For this reason, the possibility of damage is considerably higher for precast cantilever structural elements than for RC fixed base cantilevers. Statistically calculated probability of cantilever uplift for Ljubljana, which would result in severe damage, is relatively low (3% in the 50-year life span. However, the calculated value is greater than the maximum acceptable level of seismic risk for collapse. One of the possible solutions to prevent the negative influences of cantilever uplift is to consider the proper reinforcement also at the bottom of the precast elements' crosssection, or by other measures preventing uplift.

  3. Evaluation of the therapeutic efficiency of mandibular anterior implant-supported fixed bridges with cantilevers

    Institute of Scientific and Technical Information of China (English)

    WU Min-jie; WANG Xiao-jing; ZOU Li-dong; XU Wei-hua; ZHANG Xiang-hao

    2013-01-01

    Background Dental implant technology has developed rapidly in recent years.However,the use of implant-supported fixed bridges with cantilevers has been controversial.The purpose of this study was to evaluate the clinical results of the mandibular anterior implant-supported fixed bridges with a cantilever.Method Thirty-three patients (15 males,18 females; mean age,42.6 years; range 20-54 years) with two missing anterior mandibular teeth had single implant-supported fixed bridges with a cantilever.Clinical examination was recorded and radiographs were taken.The mean duration of follow-up was 30 months (15-44 months).Results All implants survived.Loosening or fracture of the prosthesis was not observed.All patients were satisfied with the treatment.The mean bone resorption values after 12,24,and 36 months of implant loading were 0.94,1.18 and 1.35 mm respectively.The changes of gingival papilla height ranged from 0 to 0.5 mm.There was significant difference between 1-year and 2 or 3 years restoration groups regarding the average gingival height changes (P <0.05).Conclusion After careful and precise selection of patients,restoration with a single implant-supported fixed bridge with a cantilever can be recommended if two anterior mandibular teeth are missing.

  4. Research progress on cantilevered resin-boned bridge%单端粘接桥的研究进展

    Institute of Scientific and Technical Information of China (English)

    张倩

    2011-01-01

    As the development of the conservative treatment, the resin-bonded bridge is a well-accepted clinical treatment to replace missing teeth, because of less tooth preparation, fewer working hours and lower cost. Recent clinical studies showed 2-unit cantilevered resin-boned bridges (CRBB) can reduce the interabutment stress and retainer debonding. Abutment selection, retention form and retainer design, metal surface treatment and luting cement are the keys to avoid the failure of CRBB. Two databases, Pubmed and China National Knowledge Infras-trudure were used to search the literatures of CRBB and investigate the effection of above factors on the longevity of CRBB, which provide the information for the clinical application of CRBB.%随着牙体保守治疗的兴起,粘接桥修复因牙体预备少、椅旁操作时间短、成本低廉等优点而广受医患的欢迎.近来的研究表明:2单位单端粘接桥可减小基牙间的应力,降低固位体的脱落率,从而获得较高的临床成功率,因而发展前景更加广泛.病例的选择、基牙固位型与固位体的设计、金属表面处理方法与粘接剂等都是影响单端粘接桥成败的关键因素.本文检索了Pubmed与中国知网数据库中的相关文章,就上述影响因素的研究现状作一综述,以供临床参考.

  5. Continuous Beam Cantilever of the Luoqing jiang Casting Construction Technology River Extra-large Bridge%洛清江特大桥连续梁悬臂灌筑施工技术

    Institute of Scientific and Technical Information of China (English)

    李锟

    2011-01-01

    This paper makes an explanation about construction technology for bridge segment No. O, the cantilever casting segment, the cast-in-situ segment and the closure segment under cantilever casting construction of the Luoqingjiang extralarge bridge which is of pre-stressed continuous box girder type. It sums up the key technology for construction of continuous beam of the Luoqingjiang extra-large double line bridge.%详细介绍洛清江双线特大桥预应力砼连续箱梁悬臂灌筑的0号号段、悬灌段、现浇段及合龙段施工技术,从而总结出洛清江双线特大桥连续梁关键施工技术。

  6. Study on control of cantilever construction of long-span continuous rigid frame bridges%大跨连续刚构桥悬臂施工控制研究

    Institute of Scientific and Technical Information of China (English)

    彭立强; 刘超; 王冲

    2015-01-01

    随着连续刚构桥施工技术的不断进步,悬臂浇筑成为在实际工程中使用最为广泛的一种连续刚构桥施工方法。在悬臂施工过程中,由于桥梁结构存在由静定结构转变为超静定结构的过程,因此在施工过程中要注意对桥梁线型、内力、预拱度以及挠度等因素进行施工过程监控,以满足桥梁结构的要求。%In recent years, with the continuous progress of the construction technology of continuous rigid frame bridge, cantilever pouring are widely used in practical engineering as a continuous rigid frame bridge construction method. There is a process for bridge structure to change from static structure to hyperstatic struc-ture in the process of the cantilever construction. Therefore, attention should be paid to the bridge linear, in-ternal forces, camber and deflection factors during the construction in order to meet the requirements of the bridge structure.

  7. Cantilever-Based Biosensors in CMOS Technology

    CERN Document Server

    Kirstein, K -U; Zimmermann, M; Vancura, C; Volden, T; Song, W H; Lichtenberg, J; Hierlemannn, A

    2011-01-01

    Single-chip CMOS-based biosensors that feature microcantilevers as transducer elements are presented. The cantilevers are functionalized for the capturing of specific analytes, e.g., proteins or DNA. The binding of the analyte changes the mechanical properties of the cantilevers such as surface stress and resonant frequency, which can be detected by an integrated Wheatstone bridge. The monolithic integrated readout allows for a high signal-to-noise ratio, lowers the sensitivity to external interference and enables autonomous device operation.

  8. NOISE AND SENSITIVITY IN POLYSILICON PIEZORESISTIVE CANTILEVERS*

    Institute of Scientific and Technical Information of China (English)

    于晓梅; 江兴流; J.THAYSEN; O.HANSEN; A.BOISEN

    2001-01-01

    Piezoresistive cantilevers with dimensions of 200 × 50 × 1.8μm3 have been fabricated from polycrystalline silicon using reactive ion etching (RIE) and back etching processes. Full Wheatstone bridges have been designed symmetrically on-chip, with two resistors placed on the cantilevers and two resistors on the substrate. The differential measurements of the two cantilevers can reduce the thermal shift of the signal in the system and the external noise in the laboratory.The characteristics of the fabricated cantilevers have been analysed by measuring the noise and the sensitivity. The measured noise spectra show that the 1/f noise is the dominant noise source at low frequencies. With the linear relation between 1/f noise and bias voltages, the Hooge factor (c) was calculated to be 0.0067. The 1/f noise was explained in terms of a lattice scattering model, which occurs in the depletion region of the grains. The displacement sensitivity of the cantilevers was calculated to be 1× 10-6nm-1 by measuring the resistance change and the vertical deflection of the cantilever. The gauge factor of the piezoresistive cantilever was calculated to be 19. At a 3V bias voltage and 1000 Hz measurement bandwidth, 1 nm of minimum detectable deflection has been obtained.

  9. Piezoelectric cantilever sensors

    Science.gov (United States)

    Shih, Wan Y. (Inventor); Shih, Wei-Heng (Inventor); Shen, Zuyan (Inventor)

    2008-01-01

    A piezoelectric cantilever with a non-piezoelectric, or piezoelectric tip useful as mass and viscosity sensors. The change in the cantilever mass can be accurately quantified by monitoring a resonance frequency shift of the cantilever. For bio-detection, antibodies or other specific receptors of target antigens may be immobilized on the cantilever surface, preferably on the non-piezoelectric tip. For chemical detection, high surface-area selective absorbent materials are coated on the cantilever tip. Binding of the target antigens or analytes to the cantilever surface increases the cantilever mass. Detection of target antigens or analytes is achieved by monitoring the cantilever's resonance frequency and determining the resonance frequency shift that is due to the mass of the adsorbed target antigens on the cantilever surface. The use of a piezoelectric unimorph cantilever allows both electrical actuation and electrical sensing. Incorporating a non-piezoelectric tip (14) enhances the sensitivity of the sensor. In addition, the piezoelectric cantilever can withstand damping in highly viscous liquids and can be used as a viscosity sensor in wide viscosity range.

  10. Cantilever Based Mass Sensing

    DEFF Research Database (Denmark)

    Dohn, Søren

    2007-01-01

    Cantilever based mass sensors utilize that a change in vibrating mass will cause a change in the resonant frequency. This can be used for very accurate sensing of adsorption and desorption processes on the cantilever surface. The change in resonant frequency caused by a single molecule depends...... on various parameters including the vibrating mass of the cantilever and the frequency at which it vibrates. The minimum amount of molecules detectable is highly dependent on the noise of the system as well as the method of readout. The aim of this Ph.D. thesis has been twofold: To develop a readout method...... suitable for a portable device and to investigate the possibility of enhancing the functionality and sensitivity of cantilever based mass sensors. A readout method based on the hard contact between the cantilever and a biased electrode placed in close proximity to the cantilever is proposed. The viability...

  11. 带有挑臂的双层钢桁悬索桥颤振性能风洞试验%Wind tunnel test for flutter stability of double-deck truss girder suspension bridge with cantilever beam

    Institute of Scientific and Technical Information of China (English)

    向活跃; 李永乐; 武兵

    2014-01-01

    为了提高加劲梁的颤振性能,针对某三塔两跨公铁两用悬索桥进行了节段模型风洞试验,探讨了多种气动措施对加劲梁颤振临界风速的影响。结果显示,在三种风攻角下,常规气动措施如增加上下桥面板中央稳定板、铁路道板及检修道开槽等措施降低了加劲梁的颤振临界风速,封闭铁路挑臂并给合上桥面板上、下中央稳定板后,加劲梁在三种风攻角下的颤振性能均大幅提高,使颤振临界风速满足要求。相关结论可为类似桥梁断面的颤振优化提供借鉴。%To improve the flutter stability of stiffened girder, the sectional model wind tunnel tests of a long span highway-railway suspension bridge with two main spans and three towers were carried out. A variety of aerodynamic measures on the flutter stability were explored. The results indicate that conventional aerodynamic measures such as the upper and lower central stabilizer, slotting rail road board and railway maintenance road reduce the critical flutter wind speed in three attack angle cases, while the flutter stability is increased significantly after closing the railway cantilever and u-sing the upper and lower central stabilizer in upper deck, which meets the requirement of standard. The conclusions can provide some references for similar bridge cross-section in the optimization of flutter stability.

  12. Vertical vibration control system for PC cable-stayed bridge during cantilever construction; Shuketa jogedo seishin sochi ni yoru haridashi sekoji no PC shachokyo no seishin

    Energy Technology Data Exchange (ETDEWEB)

    Oshio, M.; Nakano, R.; Niihara, Y.; Yano, K.; Takeda, T. [Kajima Corp., Tokyo (Japan)

    1995-12-20

    A PC cable-stayed bridge under extension construction having long span length may have long-cycle vibration generated because of wind. The vibration puts workers working on main girders into a state of seasick causing the workability to drop. Therefore, with an objective to reduce vibration occurring on the main girders during construction, discussions were given on application of an active type vertical vibration absorbing device. The vibration absorbing device is an active system that a weight is driven vertically by a hydraulic actuator. The device was developed with a target that damping ratio when a maximum extension is 120 m becomes three times that when no vibration is absorbed for a 5-span continuous PC cable-stayed bridge with a length of 675 m, a central span of 260 m, and a width of 11 m. A cage housing the weight is connected with the actuator at its top by using pins, and the weight is supported being suspended from the top of the actuator. Vibration is absorbed by utilizing reactive force generated when the weight is driven vertically by the hydraulic actuator. The hydraulic actuator contains a gas spring that supports the dead weight of the weight. Experiments have verified the effectiveness of the vertical vibration absorbing device. 4 refs., 12 figs., 3 tabs.

  13. Analysis of ultimate bearing capacity of prestressed concrete box -girder bridge with large -cantilever -wing%大悬臂展翅预应力混凝土宽箱梁桥极限承载力分析

    Institute of Scientific and Technical Information of China (English)

    余晓琳; 贾布裕; 杨铮; 颜全胜

    2015-01-01

    To study the ultimate bearing capacity of the large cantilever structure,an accurate space finite ele-ment model was built for numerical analysis with the background of a prestressed concrete box -girder bridge with large -cantilevev -wing.Taking into account of the geometric nonlinearity and the material nonlinearity, the structure ultimate bearing capacity and the distribution regularity of cracks under three load cases(eccentric concentrated load,symmetrical concentrated load and uniform distributed load)were analyzed.It is concluded that the structure ultimate bearing capacity under the load case of symmetrical load is larger than that under the case of asymmetrical load;the distributions of the stress and cracks under the load case of asymmetrical load are also asymmetrical and cracks are more likely to appear in the root of the cantilever wing.The stress condition of side span is worse than mid -span under uniformly distributed load.%针对大悬臂展翅结构的极限承载能力问题,以某大悬臂展翅预应力混凝土宽箱梁桥为实际工程背景,建立精细的空间有限元模型进行数值分析。考虑结构几何非线性和材料非线性,研究偏心集中荷载、对称集中荷载、均布荷载3种工况作用下,结构的极限承载能力及裂缝的分布规律。结果表明,对称加载形式的极限承载能力大于非对称加载形式的极限承载能力;非对称荷载作用下,桥梁应力及裂缝分布也具有较大非对称性,且悬臂板根部更加容易出现裂缝,均布荷载作用下,桥梁边跨应力状况劣于中跨。

  14. SiC-Based Miniature High-Temperature Cantilever Anemometer

    Science.gov (United States)

    Okojie, Robert S.; Fralick, Gustave; Saad, George J.

    2004-01-01

    The figure depicts a miniature cantilever-type anemometer that has been developed as a prototype of compact, relatively nonintrusive anemometers that can function at temperatures up to 600 C and that can be expected to be commercially mass-producible at low cost. The design of this anemometer, and especially the packaging aspect of the design, is intended to enable measurement of turbulence in the high-temperature, high-vibration environment of a turbine engine or in any similar environment. The main structural components of the anemometer include a single-crystal SiC cantilever and two polycrystalline SiC clamping plates, all made from chemical-vapor-deposited silicon carbide. Fabrication of these components from the same basic material eliminates thermal-expansion mismatch, which has introduced spurious thermomechanical stresses in cantilever-type anemometers of prior design. The clamping plates are heavily oxidized to improve electrical insulation at high temperature. A cavity that serves as a receptacle for the clamped end of the cantilever is etched into one end of one clamping plate. Trenches that collectively constitute a socket for a multipin electrical plug (for connection to external electronic circuitry) are etched into the opposite end of this clamping plate. Metal strips for electrical contact are deposited on one face of the other clamping plate. Piezoresistive single-crystal SiC thin-film strain gauges are etched in the n-type SiC epilayer in a Wheatstone-bridge configuration. Metal contact pads on the cantilever that extend into the clamping-receptacle area, are obtained by deposition and patterning using standard semiconductor photolithography and etching methods. The cantilever and the two clamping plates are assembled into a sandwich structure that is then clamped in a stainless-steel housing. The Wheatstone- bridge carrying SiC cantilever with the metal contact pads on the piezoresistors is slid into the receptacle in the bottom clamping plate

  15. Analogies between a Meniscus and a Cantilever

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-Lin

    2009-01-01

    Systematic and quantitative analyses of exact analogies between a meniscus and an elastica are performed. It is shown that the two governing equations take the same style after coordinate translation and scale transformation. The morphologies of the liquid bridge and the cantilever are calculated in terms of elliptic integrations, which can be reduced to the same shape,after converting the boundary conditions. The present analyses can make us grasp the nature of this physical phenomenon deeply and show some inspiration for designing the analogy experiments. Moreover, the calculated results are helpful to engineering applications, such as design and fabrication of MEMS, and micro-manipulations in micro/nano- technology.

  16. Biosensors based on cantilevers.

    Science.gov (United States)

    Alvarez, Mar; Carrascosa, Laura G; Zinoviev, Kiril; Plaza, Jose A; Lechuga, Laura M

    2009-01-01

    Microcantilevers based-biosensors are a new label-free technique that allows the direct detection of biomolecular interactions in a label-less way and with great accuracy by translating the biointeraction into a nanomechanical motion. Low cost and reliable standard silicon technologies are widely used for the fabrication of cantilevers with well-controlled mechanical properties. Over the last years, the number of applications of these sensors has shown a fast growth in diverse fields, such as genomic or proteomic, because of the biosensor flexibility, the low sample consumption, and the non-pretreated samples required. In this chapter, we report a dedicated design and a fabrication process of highly sensitive microcantilever silicon sensors. We will describe as well an application of the device in the environmental field showing the immunodetection of an organic toxic pesticide as an example. The cantilever biofunctionalization process and the subsequent pesticide determination are detected in real time by monitoring the nanometer-scale bending of the microcantilever due to a differential surface stress generated between both surfaces of the device.

  17. Chemical sensor with oscillating cantilevered probe

    Science.gov (United States)

    Adams, Jesse D

    2013-02-05

    The invention provides a method of detecting a chemical species with an oscillating cantilevered probe. A cantilevered beam is driven into oscillation with a drive mechanism coupled to the cantilevered beam. A free end of the oscillating cantilevered beam is tapped against a mechanical stop coupled to a base end of the cantilevered beam. An amplitude of the oscillating cantilevered beam is measured with a sense mechanism coupled to the cantilevered beam. A treated portion of the cantilevered beam is exposed to the chemical species, wherein the cantilevered beam bends when exposed to the chemical species. A second amplitude of the oscillating cantilevered beam is measured, and the chemical species is determined based on the measured amplitudes.

  18. Cantilever sensors: Nanomechanical tools for diagnostics

    DEFF Research Database (Denmark)

    Datar, R.; Kim, S.; Jeon, S.;

    2009-01-01

    Cantilever sensors have attracted considerable attention over the last decade because of their potential as a highly sensitive sensor platform for high throughput and multiplexed detection of proteins and nucleic acids. A micromachined cantilever platform integrates nanoscale science and microfab...

  19. Cantilever-like micromechanical sensors

    DEFF Research Database (Denmark)

    Boisen, Anja; Dohn, Søren; Keller, Stephan Sylvest

    2011-01-01

    The field of cantilever-based sensing emerged in the mid-1990s and is today a well-known technology for label-free sensing which holds promise as a technique for cheap, portable, sensitive and highly parallel analysis systems. The research in sensor realization as well as sensor applications has...... increased significantly over the past 10 years. In this review we will present the basic modes of operation in cantilever-like micromechanical sensors and discuss optical and electrical means for signal transduction. The fundamental processes for realizing miniaturized cantilevers are described with focus...... on silicon-and polymer-based technologies. Examples of recent sensor applications are given covering such diverse fields as drug discovery, food diagnostics, material characterizations and explosives detection....

  20. Polymeric Cantilever Arrays for Biosensing Applications

    DEFF Research Database (Denmark)

    Calleja, M.; Tamayo, J.; Johansson, Alicia

    2003-01-01

    We report the fabrication of arrays of polymeric cantilevers for biochemistry applications. The cantilevers are fabricated in the polymer SU-8. The use of a polymer as the component material for the cantilevers provides the sensors with very high sensitivity due to convenient mechanical material...... properties. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. The method allows obtaining well-controlled and uniform mechanical properties of the cantilevers. The elastic constant of the cantilevers was measured, and their dynamic response...

  1. Chemical Sensors Based on Piezoresistive Cantilever Array

    Institute of Scientific and Technical Information of China (English)

    于晓梅; 张大成; 王丛舜; 杜先锋; 王小宝; 阮勇

    2003-01-01

    U-shaped and rectangle piezoresistive cantilever arrays have been designed with the analysing results of stress,noise and sensitivity of the cantilevers. Based on silicon micromachining technology, the piezoresistive cantilevers were fabricated by using polysilicon as the piezoresistive materials. With the measurement results of noise and sensitivity, the Hooge factor is calculated to be 3 × 10-3, the gauge factor is 27, and the minimum detectable deflection of piezoresistive cantilevers are calculated to be 1.0nm for rectangle cantilever and 0.5 nm for the Ushaped cantilever at a 6 V bias voltage and a 1000 Hz measurement bandwidth. Using polymer-coated cantilevers as individual sensors, their responses to water vapour and ammonia were tested by measuring their output voltage signals. The measured results show that the sensor sensitivity to ammonia can reach a few ppm and the sensor responses are quick.

  2. Cantilevered probe detector with piezoelectric element

    Science.gov (United States)

    Adams, Jesse D; Sulchek, Todd A; Feigin, Stuart C

    2013-04-30

    A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

  3. SU-8 cantilever chip interconnection

    DEFF Research Database (Denmark)

    Johansson, Alicia Charlotte; Janting, Jakob; Schultz, Peter;

    2006-01-01

    the electrodes on the SU-8 chip to a printed circuit board. Here, we present two different methods of electrically connecting an SU-8 chip, which contains a microfluidic network and free-hanging mechanical parts. The tested electrical interconnection techniques are flip chip bonding using underfill or flip chip...... bonding using an anisotropic conductive film (ACF). These are both widely used in the Si industry and might also be used for the large scale interconnection of SU-8 chips. The SU-8 chip, to which the interconnections are made, has a microfluidic channel with integrated micrometer-sized cantilevers...... that can be used for label-free biochemical detection. All the bonding tests are compared with results obtained using similar Si chips. It is found that it is significantly more complicated to interconnect SU-8 than Si cantilever chips primarily due to the softness of SU-8....

  4. MEMS-based silicon cantilevers with integrated electrothermal heaters for airborne ultrafine particle sensing

    Science.gov (United States)

    Wasisto, Hutomo Suryo; Merzsch, Stephan; Waag, Andreas; Peiner, Erwin

    2013-05-01

    The development of low-cost and low-power MEMS-based cantilever sensors for possible application in hand-held airborne ultrafine particle monitors is described in this work. The proposed resonant sensors are realized by silicon bulk micromachining technology with electrothermal excitation, piezoresistive frequency readout, and electrostatic particle collection elements integrated and constructed in the same sensor fabrication process step of boron diffusion. Built-in heating resistor and full Wheatstone bridge are set close to the cantilever clamp end for effective excitation and sensing, respectively, of beam deflection. Meanwhile, the particle collection electrode is located at the cantilever free end. A 300 μm-thick, phosphorus-doped silicon bulk wafer is used instead of silicon-on-insulator (SOI) as the starting material for the sensors to reduce the fabrication costs. To etch and release the cantilevers from the substrate, inductively coupled plasma (ICP) cryogenic dry etching is utilized. By controlling the etching parameters (e.g., temperature, oxygen content, and duration), cantilever structures with thicknesses down to 10 - 20 μm are yielded. In the sensor characterization, the heating resistor is heated and generating thermal waves which induce thermal expansion and further cause mechanical bending strain in the out-of-plane direction. A resonant frequency of 114.08 +/- 0.04 kHz and a quality factor of 1302 +/- 267 are measured in air for a fabricated rectangular cantilever (500x100x13.5 μm3). Owing to its low power consumption of a few milliwatts, this electrothermal cantilever is suitable for replacing the current external piezoelectric stack actuator in the next generation of the miniaturized cantilever-based nanoparticle detector (CANTOR).

  5. Construction Technology of Long Span Bridges

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    2000-01-01

    A large variety of construction methods are used during construction of major bridges, and in many cases the final structural system must be chosen with due respect to the construction process. Today the preferred construction methods are: the free-cantilever method, the launching method and the ......A large variety of construction methods are used during construction of major bridges, and in many cases the final structural system must be chosen with due respect to the construction process. Today the preferred construction methods are: the free-cantilever method, the launching method...

  6. Determining cantilever stiffness from thermal noise

    Directory of Open Access Journals (Sweden)

    Jannis Lübbe

    2013-03-01

    Full Text Available We critically discuss the extraction of intrinsic cantilever properties, namely eigenfrequency fn, quality factor Qn and specifically the stiffness kn of the nth cantilever oscillation mode from thermal noise by an analysis of the power spectral density of displacement fluctuations of the cantilever in contact with a thermal bath. The practical applicability of this approach is demonstrated for several cantilevers with eigenfrequencies ranging from 50 kHz to 2 MHz. As such an analysis requires a sophisticated spectral analysis, we introduce a new method to determine kn from a spectral analysis of the demodulated oscillation signal of the excited cantilever that can be performed in the frequency range of 10 Hz to 1 kHz regardless of the eigenfrequency of the cantilever. We demonstrate that the latter method is in particular useful for noncontact atomic force microscopy (NC-AFM where the required simple instrumentation for spectral analysis is available in most experimental systems.

  7. Optical fibre cantilever sensor for biological application

    Science.gov (United States)

    Li, J.; Zhou, Y. X.; Patterson, G.; Shu, W. M.; Maier, R. R. J.; Fowler, R.; Hand, D. P.; MacPherson, W. N.

    2014-05-01

    Micro-cantilever sensors have shown great promise in a wide range of application are as including chemical and biological sensing. However, many of these devices are based upon a sensor `chip' that requires careful alignment between the cantilever and the read-out system, which can be challenging. Furthermore, optical interrogation typically involves a bulky free-space system. Optical fibre addressed cantilevers have been reported previously in the literature and in this paper we propose techniques to design and fabricate polymer micro-cantilevers for attachment onto the end of standard single mode fibres using laser machining. Low-cost optical sources and a fibre coupled spectrometer are employed to monitor the cantilever deflection and therefore observe biological binding between a species of interest and an activated cantilever. Proof-of-concept experiments show that the sensor is capable of detecting pathogen concentration with down to a level of 105cfu/ml.

  8. Nanomechanical humidity detection through porous alumina cantilevers

    Directory of Open Access Journals (Sweden)

    Olga Boytsova

    2015-06-01

    Full Text Available We present here the behavior of the resonance frequency of porous anodic alumina cantilever arrays during water vapor adsorption and emphasize their possible use in the micromechanical sensing of humidity levels at least in the range of 10–22%. The sensitivity of porous anodic aluminium oxide cantilevers (Δf/Δm and the humidity sensitivity equal about 56 Hz/pg and about 100 Hz/%, respectively. The approach presented here for the design of anodic alumina cantilever arrays by the combination of anodic oxidation and photolithography enables easy control over porosity, surface area, geometric and mechanical characteristics of the cantilever arrays for micromechanical sensing.

  9. Continuous rigid PC frame box girder cantilever pouring construction reasonable maintenance method

    Directory of Open Access Journals (Sweden)

    Wulin

    2015-08-01

    Full Text Available In recent years, prestressed concrete continuous rigid frame box girder plate and web plate produced a large number of non-structural cracks disease caused the attention of large bridge workers, to solve the problem of continuous rigid-frame structure of the cantilever of the disease, this article briefly introduced the cantilever construction method and the performance requirements of modern concrete, through to the modern concrete composition change and keeping in good health on the impact of environment on its early performance analysis summary, points out the present problems of box girder early curing, finally combining with the characteristics of modern concrete performance and the characteristics of the cantilever construction method, puts forward "model attach +manual+automatic water spray mist stick " composite curing method in order to reduce the structural cracks, provides a new train of thought.

  10. Cantilevers orthodontics forces measured by fiber sensors

    Science.gov (United States)

    Schneider, Neblyssa; Milczewski, Maura S.; de Oliveira, Valmir; Guariza Filho, Odilon; Lopes, Stephani C. P. S.; Kalinowski, Hypolito J.

    2015-09-01

    Fibers Bragg Gratings were used to evaluate the transmission of the forces generates by orthodontic mechanic based one and two cantilevers used to move molars to the upright position. The results showed levels forces of approximately 0,14N near to the root of the molar with one and two cantilevers.

  11. 某预应力混凝土箱梁桥悬臂施工中底板纵向裂缝成因分析及处理措施%Analysis of Causes Inducing Longitudinal Cracks in Base Slabs During Cantilever Construction of A Prestressed Concrete Box Girder Bridge and Treating Measures

    Institute of Scientific and Technical Information of China (English)

    胡志红; 王攀; 邹红丹

    2015-01-01

    The bridge cited as an example in this study is a combined prestressed concrete con-tinuous beam and rigid-frame composite box girder bridge with span arrangement of(80+2 × 150+80) m.The box girder adopts the two-cell single box cross section with straight diaphragms ,cas-ted in situ in cantilevers using form travelers.During the construction of the first 8 sections ,longi-tudinal cracks were found in the base slabs of the box girder.ANSYS was used to establish the fi-nite element models of the No.1 and No.2 box girder sections and calculate the stress distribution condition of the girder under 4 load cases.By analyzing the distributive law of the cracks in the base slabs of the girder ,the transverse stress and temperature during the curing of the box girder concrete were monitored.and the causes inducing longitudinal cracks in the base slabs of the box girder was analyzed.The results of the analysis indicate that the gradient thermal loading effect in-side the concrete takes the major responsibility for longitudinal cracks.T hen the measures for in-tensifying the transverse prestressing tendons in the base slabs of box girder were proposed.The curing of base slabs should also be given enough attention.By using the aforementioned measures , no marked longitudinal cracks were found in the base slabs of the box girder during the construc-tion monitoring of the girder sections.%某预应力混凝土连续梁-刚构组合箱梁桥跨径布置为(80+2 × 150+80 ) m ,箱梁为直腹板单箱双室截面 ,采用挂篮悬臂现浇施工 ,在前8个节段的施工过程中 ,箱梁底板出现了纵向裂缝.采用ANSYS建立1号、2号节段箱梁实体有限元模型 ,计算4种荷载工况下箱体的应力分布情况 ,并监测箱梁混凝土养护过程中的横向应力和温度 ,分析了箱梁底板纵向裂缝开裂原因.分析得出混凝土内部的梯度温度荷载效应是底板产生纵向裂缝的主要原因 ,提出加强箱梁底板的横向配筋及

  12. Three-way flexible cantilever probes for static contact

    DEFF Research Database (Denmark)

    Wang, Fei; Petersen, Dirch Hjorth; Jensen, Helle Vendelbo;

    2011-01-01

    In micro four-point probe measurements, three-way flexible L-shaped cantilever probes show significant advantages over conventional straight cantilever probes. The L-shaped cantilever allows static contact to the sample surface which reduces the frictional wear of the cantilever tips. We analyze...

  13. Improved cantilever profiles for sensor elements

    Energy Technology Data Exchange (ETDEWEB)

    Fernando, Sanchitha [School of Electrical and Computer Engineering, RMIT University, GPO Box 2476V, Melbourne, VIC 3001 (Australia); Austin, Michael [School of Electrical and Computer Engineering, RMIT University, GPO Box 2476V, Melbourne, VIC 3001 (Australia); Chaffey, Jason [Mems-ID, MiniFAB, 1 Dalmore Drive, Caribbean Park, Scoresby, VIC 3179 (Australia)

    2007-12-21

    The problem of simultaneously enhancing sensitivity and noise immunity of microcantilevers is investigated. The dependence of deflection and resonant frequency of a microcantilever on its dimensions is studied. A principle to increase deflection and resonant frequency simultaneously is established. Several cantilevers agreeing with this principle are investigated using analytical models and are compared with FEM simulations. Using these results, a cantilever profile that achieves a larger deflection and a larger resonant frequency compared with uniform cantilevers is proposed to be used in sensor elements.

  14. Improved cantilever profiles for sensor elements

    Science.gov (United States)

    Fernando, Sanchitha; Austin, Michael; Chaffey, Jason

    2007-12-01

    The problem of simultaneously enhancing sensitivity and noise immunity of microcantilevers is investigated. The dependence of deflection and resonant frequency of a microcantilever on its dimensions is studied. A principle to increase deflection and resonant frequency simultaneously is established. Several cantilevers agreeing with this principle are investigated using analytical models and are compared with FEM simulations. Using these results, a cantilever profile that achieves a larger deflection and a larger resonant frequency compared with uniform cantilevers is proposed to be used in sensor elements.

  15. Design & fabrication of cantilever array biosensors

    Directory of Open Access Journals (Sweden)

    Anja Boisen

    2009-09-01

    Full Text Available Surface immobilization of functional receptors on microfabricated cantilever arrays offers a new paradigm for the development of biosensors based on nanomechanics. Microcantilever-based systems are capable of real-time, multiplexed detection of unlabeled disease markers in extremely small volumes of samples. Currently available fabrication technology will allow the integration of electronic readout and sample introduction into a single unit, decreasing the device size, detection time, and cost. Biosensing technologies based on microfabricated cantilever arrays involving multiple cantilevers, electronic processing, and even local telemetry on a single chip have the potential of satisfying the need for highly sensitive and selective multiple-target detection in very small samples. Here we will review the design and fabrication process of cantilever-based biosensors.

  16. Grating Loaded Cantilevers for Displacement Measurements

    Science.gov (United States)

    Karademir, Ertugrul; Olcum, Selim; Atalar, Abdullah; Aydinli, Atilla

    2010-03-01

    A cantilever with a grating coupler engraved on its tip is used for measuring displacement. The coupled light in the cantilever is guided to a single mode optical waveguide defined at the base of the cantilever. The grating period is 550 nm and is fabricated on a SOI wafer using nanoimprint lithography. The waveguide and the cantilever are defined by an RIE and cantilevers released by KOH and HF solutions. Light with 1550 nm wavelength, is directed onto the grating coupler and detected at the cleaved end of the SOI waveguide. The angle of incidence is controlled by a motorized rotary stage. Light couples into the waveguide at a characteristic angle with a full width at half maximum of approximately 6.9 mrads translating into a Q factor of 87.5. The displacement sensitivity is measured by driving the cantilever with a frequency controlled piezoelectric element. The modulation of the light at the waveguide output is lock-in detected by a biased infrared detector. The resulting 43%mrad-1 sensitivity can be increased with further optimization.

  17. A new bi-axial cantilever beam design for biomechanics force measurements.

    Science.gov (United States)

    Lin, Huai-Ti; Trimmer, Barry A

    2012-08-31

    The demand for measuring forces exerted by animals during locomotion has increased dramatically as biomechanists strive to understand and implement biomechanical control strategies. In particular, multi-axial force transducers are often required to capture animal limb coordination patterns. Most existing force transducers employ strain gages arranged in a Wheatstone bridge on a cantilever beam. Bi-axial measurements require duplicating this arrangement in the transverse direction. In this paper, we reveal a method to embed a Wheatstone bridge inside another to allow bi-axial measurements without additional strain gages or additional second beams. This hybrid configuration resolves two force components from a single bridge circuit and simplifies fabrication for the simultaneous assessment of normal and transverse loads. This design can be implemented with two-dimensional fabrication techniques and can even be used to modify a common full bridge cantilever force transducer. As a demonstration of the new design, we built a simple beam which achieved bi-axial sensing capability that outperformed a conventional half-bridge-per-axis bi-axial strain gage design. We have used this design to measure the ground reaction forces of a crawling caterpillar and a caterpillar-mimicking soft robot. The simplicity and increased sensitivity of this method could facilitate bi-axial force measurements for experimental biologists.

  18. Measurement of Local Si-Nanowire Growth Kinetics Using In situ Transmission Electron Microscopy of Heated Cantilevers

    DEFF Research Database (Denmark)

    Kallesøe, Christian; Wen, Cheng-Yen; Mølhave, Kristian;

    2010-01-01

    A technique to study nanowire growth processes on locally heated microcantilevers in situ in a transmission electron microscope has been developed. The in situ observations allow the characterization of the nucleation process of silicon wires, as well as the measurement of growth rates...... of individual nanowires and the ability to observe the formation of nanowire bridges between separate cantilevers to form a complete nanowire device. How well the nanowires can be nucleated controllably on typical cantilever sidewalls is examined, and the measurements of nanowire growth rates are used...

  19. Asymmetric resonance frequency analysis of in-plane electrothermal silicon cantilevers for nanoparticle sensors

    Science.gov (United States)

    Bertke, Maik; Hamdana, Gerry; Wu, Wenze; Marks, Markus; Suryo Wasisto, Hutomo; Peiner, Erwin

    2016-10-01

    The asymmetric resonance frequency analysis of silicon cantilevers for a low-cost wearable airborne nanoparticle detector (Cantor) is described in this paper. The cantilevers, which are operated in the fundamental in-plane resonance mode, are used as a mass-sensitive microbalance. They are manufactured out of bulk silicon, containing a full piezoresistive Wheatstone bridge and an integrated thermal heater for reading the measurement output signal and stimulating the in-plane excitation, respectively. To optimize the sensor performance, cantilevers with different cantilever geometries are designed, fabricated and characterized. Besides the resonance frequency, the quality factor (Q) of the resonance curve has a high influence concerning the sensor sensitivity. Because of an asymmetric resonance behaviour, a novel fitting function and method to extract the Q is created, different from that of the simple harmonic oscillator (SHO). For testing the sensor in a long-term frequency analysis, a phase- locked loop (PLL) circuit is employed, yielding a frequency stability of up to 0.753 Hz at an Allan variance of 3.77 × 10-6. This proposed asymmetric resonance frequency analysis method is expected to be further used in the process development of the next-generation Cantor.

  20. Adaptive control of force microscope cantilever dynamics

    Science.gov (United States)

    Jensen, S. E.; Dougherty, W. M.; Garbini, J. L.; Sidles, J. A.

    2007-09-01

    Magnetic resonance force microscopy (MRFM) and other emerging scanning probe microscopies entail the detection of attonewton-scale forces. Requisite force sensitivities are achieved through the use of soft force microscope cantilevers as high resonant-Q micromechanical oscillators. In practice, the dynamics of these oscillators are greatly improved by the application of force feedback control computed in real time by a digital signal processor (DSP). Improvements include increased sensitive bandwidth, reduced oscillator ring up/down time, and reduced cantilever thermal vibration amplitude. However, when the cantilever tip and the sample are in close proximity, electrostatic and Casimir tip-sample force gradients can significantly alter the cantilever resonance frequency, foiling fixed-gain narrow-band control schemes. We report an improved, adaptive control algorithm that uses a Hilbert transform technique to continuously measure the vibration frequency of the thermally-excited cantilever and seamlessly adjust the DSP program coefficients. The closed-loop vibration amplitude is typically 0.05 nm. This adaptive algorithm enables narrow-band formally-optimal control over a wide range of resonance frequencies, and preserves the thermally-limited signal to noise ratio (SNR).

  1. Physics-based signal processing algorithms for micromachined cantilever arrays

    Science.gov (United States)

    Candy, James V; Clague, David S; Lee, Christopher L; Rudd, Robert E; Burnham, Alan K; Tringe, Joseph W

    2013-11-19

    A method of using physics-based signal processing algorithms for micromachined cantilever arrays. The methods utilize deflection of a micromachined cantilever that represents the chemical, biological, or physical element being detected. One embodiment of the method comprises the steps of modeling the deflection of the micromachined cantilever producing a deflection model, sensing the deflection of the micromachined cantilever and producing a signal representing the deflection, and comparing the signal representing the deflection with the deflection model.

  2. Design & fabrication of cantilever array biosensors

    DEFF Research Database (Denmark)

    Boisen, Anja; Thundat, T

    2009-01-01

    Surface immobilization of functional receptors on microfabricated cantilever arrays offers a new paradigm for the development of biosensors based on nanomechanics. Microcantilever-based systems are capable of real-time, multiplexed detection of unlabeled disease markers in extremely small volumes......, electronic processing, and even local telemetry on a single chip have the potential of satisfying the need for highly sensitive and selective multiple-target detection in very small samples. Here we will review the design and fabrication process of cantilever-based biosensors....

  3. Electronically droplet energy harvesting using piezoelectric cantilevers

    KAUST Repository

    Al Ahmad, Mahmoud Al

    2012-01-01

    A report is presented on free falling droplet energy harvesting using piezoelectric cantilevers. The harvester incorporates a multimorph clamped-free cantilever which is composed of five layers of lead zirconate titanate piezoelectric thick films. During the impact, the droplet kinetic energy is transferred into the form of mechanical stress forcing the piezoelectric structure to vibrate. Experimental results show energy of 0.3 μJ per droplet. The scenario of moderate falling drop intensity, i.e. 230 drops per second, yields a total energy of 400 μJ. © 2012 The Institution of Engineering and Technology.

  4. Functionally graded piezoelectric cantilever beam under load

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Z.F.; Chen, Y. [Beijing Jiaotong University, School of Civil Engineering, Beijing (China)

    2004-12-01

    In the present paper, the problem of a functionally graded piezoelectric cantilever beam subjected to different loadings is studied. The piezoelectric beam is characterized by continuously graded properties for one elastic parameter and the material density. A pair of stress and induction functions in the form of polynomials is proposed and determined. Based on these functions, a set of analytical solutions for the beam subjected to different loadings is obtained. As particular cases, series of solutions for some canonical problems can be directly obtained from the solutions of the present paper, such as for the problems of a piezoelectric cantilever beam with constant body force or without body forces, etc. (orig.)

  5. Polymeric cantilever-based biosensors with integrated readout

    DEFF Research Database (Denmark)

    Johansson, Alicia; Blagoi, Gabriela; Boisen, Anja

    2006-01-01

    The authors present an SU-8 cantilever chip with integrated piezoresistors for detection of surface stress changes due to adsorption of biomolecules on the cantilever surface. Mercaptohexanol is used as a model biomolecule to study molecular interactions with Au-coated SU-8 cantilevers and surfac...

  6. Railroad Bridges

    Data.gov (United States)

    Department of Homeland Security — Bridges-Rail in the United States According to The National Bridge Inspection Standards published in the Code of Federal Regulations (23 CFR 650.3), a bridge isA...

  7. From MEMS to NEMS: Scaling Cantilever Sensors

    NARCIS (Netherlands)

    Yang, C.K.

    2012-01-01

    This thesis studies the effects of scaling on the characterisation and readout of micro-electro mechanical systems (MEMS) to nano-electro mechanical systems (NEMS). In particular it focuses on cantilever, which is a basic device building block and an important transducer in many sensing application

  8. Forced Vibrations of a Cantilever Beam

    Science.gov (United States)

    Repetto, C. E.; Roatta, A.; Welti, R. J.

    2012-01-01

    The theoretical and experimental solutions for vibrations of a vertical-oriented, prismatic, thin cantilever beam are studied. The beam orientation is "downwards", i.e. the clamped end is above the free end, and it is subjected to a transverse movement at a selected frequency. Both the behaviour of the device driver and the beam's weak-damping…

  9. Dynamic Characterization of Silicon Nitride Cantilevers

    NARCIS (Netherlands)

    Babaei Gavan, K.

    2009-01-01

    This thesis describes a series of experiments on dynamical characterization of silicon nitride cantilevers. These devices play an important role in micro-and nanoelectromechanical systems (MEMS and NEMS). They consist of a mechanical part, a sensor or actuator, and an electronic part for readout and

  10. Microstructure cantilever beam for current measurement

    Directory of Open Access Journals (Sweden)

    M.T.E. Khan

    2010-01-01

    Full Text Available Most microelectromechanical systems (MEMS sensors are based on the microcantilever technology, which uses a broad range of design materials and structures. The benefit ofMEMStechnology is in developing devices with a lower cost, lower power consumption, higher performance and greater integration. A free-end cantilever beam with a magnetic material mass has been designed using MEMS software tools. The magnetic material was used to improve the sensitivity of the cantilever beam to an externally-applied magnetic field. The cantilever was designed to form a capacitance transducer, which consisted of variable capacitance where electrical and mechanical energies were exchanged. The aim of this paper was to analyse the system design of the microcantilever when subjected to a magnetic field produced by a current-carrying conductor. When the signal, a sinusoidal current with a constant frequency, was applied, the cantilever beam exhibited a vibration motion along the vertical axis when placed closer to the line current. This motion created corresponding capacitance changes and generated a voltage output proportional to the capacitive change in the signal-processing circuitry attached to the microcantilever. The equivalent massspring system theory was used to describe and analyse the effect of the natural frequency of the system vibrations and motion due to the applied magnetic field, in a single-degree of freedom. The main application of this microcantilever is in current measurements to develop a non-contact current sensor mote.

  11. Improved atomic force microscopy cantilever performance by partial reflective coating

    Directory of Open Access Journals (Sweden)

    Zeno Schumacher

    2015-07-01

    Full Text Available Optical beam deflection systems are widely used in cantilever based atomic force microscopy (AFM. Most commercial cantilevers have a reflective metal coating on the detector side to increase the reflectivity in order to achieve a high signal on the photodiode. Although the reflective coating is usually much thinner than the cantilever, it can still significantly contribute to the damping of the cantilever, leading to a lower mechanical quality factor (Q-factor. In dynamic mode operation in high vacuum, a cantilever with a high Q-factor is desired in order to achieve a lower minimal detectable force. The reflective coating can also increase the low-frequency force noise. In contact mode and force spectroscopy, a cantilever with minimal low-frequency force noise is desirable. We present a study on cantilevers with a partial reflective coating on the detector side. For this study, soft (≈0.01 N/m and stiff (≈28 N/m rectangular cantilevers were used with a custom partial coating at the tip end of the cantilever. The Q-factor, the detection and the force noise of fully coated, partially coated and uncoated cantilevers are compared and force distance curves are shown. Our results show an improvement in low-frequency force noise and increased Q-factor for the partially coated cantilevers compared to fully coated ones while maintaining the same reflectivity, therefore making it possible to combine the best of both worlds.

  12. Vortex Anemometer Using MEMS Cantilever Sensor

    CERN Document Server

    Zylka, P; Zylka, Pawel; Modrzynski, Pawel

    2010-01-01

    This paper presents construction and performance of a novel hybrid microelectromechanical system (MEMS) vortex flowmeter. A miniature cantilever MEMS displacement sensor was used to detect frequency of vortices development. 3-mm-long silicon cantilever, protruding directly out of a trailing edge of a trapezoidal glass-epoxy composite bluff body was put into oscillatory motion by vortices shed alternately from side surfaces of the obstacle. Verified linearmeasurement range of the device extended from 5 to 22 m/s; however, it could be broadened in absence of external 50-Hz mains electrical interfering signal which required bandpass frequency-domain digital sensor signal processing. The MEMS vortex sensor proved its effectiveness in detection of semilaminar airflow velocity distribution in a 40-mm-diameter tubular pipe.

  13. Inner Crack Detection Method for Cantilever Beams

    Science.gov (United States)

    Li, Zheng; Zhang, Wei; Li, Yixuan; Su, Xianyue

    2008-02-01

    In this paper, continuous wavelet transform has been performed to extract the inner crack information from the guided waves in cantilever beams, and the location and size of crack can be detected exactly. Considering its best time-frequency property, Gabor continuous wavelet transform is employed to analyze the complicated flexible wave signals in cantilever beam, which is inspirited by an impact on the free end. Otherwise, in order to enhance the sensitivity of detection for some small cracks, an improved method is discussed. Here, both computational and experimental methods are carried out for comparing the influence of different crack location in beam. Therefore, the method proposed can be expected to expand to a powerful damage detection method in a broad engineering application.

  14. Cantilever steel post damaged by wind

    Directory of Open Access Journals (Sweden)

    Wei Sha

    2014-10-01

    Full Text Available An analysis for the cause of fracture failure of a cantilever steel sign post damaged by wind has been carried out. An unusual cause of failure has been identified, which is the subject of this paper. Microscopy and microanalysis of the fracture surface showed that the failure was due to pre-existing cracks, from the fabrication of the post. This conclusion was reached after detecting and analysing a galvanised layer on the fracture surfaces.

  15. Multifunctionalized cantilever systems for electronic nose applications.

    Science.gov (United States)

    Yoo, Yong Kyoung; Chae, Myung-Sic; Kang, Ji Yoon; Kim, Tae Song; Hwang, Kyo Seon; Lee, Jeong Hoon

    2012-10-02

    Multiple target detection using a cantilever is essential for biosensor, chemical sensor, and electronic nose systems. We report a novel microcantilever array chip that includes four microreaction chambers in a chip, which consequently contains four different functionalized surfaces for multitarget detection. For model tests, we designed microcantilever chips and demonstrated the ability of binding of 2,4-dinitrotoluene (DNT) targets onto four different surfaces. We used peptide receptors that are known to have highly selective binding. By simply using four microreaction chambers, we immobilized DNT specific peptide (HPNFSKYILHQRC; SP), DNT nonspecific peptide (TSMLLMSPKHQAC; NSP), and self-assembled monolayer (SAM) as well as a bare cantilever. After flowing DNT gases through the cantilever chip, we could monitor the four different binding signals simultaneously. The shifts in NSP provided information as a negative control because it contained information of temperature fluctuations and mechanical vibration from gas flow. By utilizing the differential signal of the SP and NSP, we acquired 7.5 Hz in resonant responses that corresponds with 160 part per billion (ppb) DNT concentration, showing the exact binding response by eliminating the inevitable thermal noise, vibration noise, as well as humidity effects on the peptide surface.

  16. Magnetic properties of cobalt microwires measured by piezoresistive cantilever magnetometry

    Directory of Open Access Journals (Sweden)

    Tosolini G.

    2014-09-01

    Full Text Available We present the magnetic characterization of cobalt wires grown by focused electron beam-induced deposition (FEBID and studied using static piezoresistive cantilever magnetometry. We have used previously developed high force sensitive submicron-thick silicon piezoresistive cantilevers. High quality polycrystalline cobalt microwires have been grown by FEBID onto the free end of the cantilevers using dual beam equipment. In the presence of an external magnetic field, the magnetic cobalt wires become magnetized, which leads to the magnetic field dependent static deflection of the cantilevers. We show that the piezoresistive signal from the cantilevers, corresponding to a maximum force of about 1 nN, can be measured as a function of the applied magnetic field with a good signal to noise ratio at room temperature. The results highlight the flexibility of the FEBID technique for the growth of magnetic structures on specific substrates, in this case piezoresistive cantilevers.

  17. Understanding interferometry for micro-cantilever displacement detection

    Directory of Open Access Journals (Sweden)

    Alexander von Schmidsfeld

    2016-06-01

    Full Text Available Interferometric displacement detection in a cantilever-based non-contact atomic force microscope (NC-AFM operated in ultra-high vacuum is demonstrated for the Michelson and Fabry–Pérot modes of operation. Each mode is addressed by appropriately adjusting the distance between the fiber end delivering and collecting light and a highly reflective micro-cantilever, both together forming the interferometric cavity. For a precise measurement of the cantilever displacement, the relative positioning of fiber and cantilever is of critical importance. We describe a systematic approach for accurate alignment as well as the implications of deficient fiber–cantilever configurations. In the Fabry–Pérot regime, the displacement noise spectral density strongly decreases with decreasing distance between the fiber-end and the cantilever, yielding a noise floor of 24 fm/Hz0.5 under optimum conditions.

  18. Bending characteristic of a cantilevered magnetostrictive film-substrate system

    Institute of Scientific and Technical Information of China (English)

    B.; Narsu

    2007-01-01

    The bending problem of a film-substrate cantilever with arbitrary film-to-substrate thickness ratio is solved exactly by employing the force equilibrium equation, and then the optimization and application of the bending characteristic of the magne-tostrictive cantilever is discussed. Furthermore, the influence of geometrical and physical parameters of the two cantilever components on the maximum free-end deflection of the cantilever is addressed. The results indicate that as the substrate thickness is kept constant, the greater film-to-substrate stiffness ratio will induce a larger deflection, while for the case of fixed total cantilever thickness, the optimal cantilever deflection is independent of the physical parameters of the materials such as Young’s modulus and Poisson’s ratio.

  19. Bending characteristic of a cantilevered magnetostrictive film-substrate system

    Institute of Scientific and Technical Information of China (English)

    B. Narsu; YUN GuoHong

    2007-01-01

    The bending problem of a film-substrate cantilever with arbitrary film-to-substrate thickness ratio is solved exactly by employing the force equilibrium equation, and then the optimization and application of the bending characteristic of the magnetostrictive cantilever is discussed. Furthermore, the influence of geometrical and physical parameters of the two cantilever components on the maximum free-end deflection of the cantilever is addressed. The results indicate that as the substrate thickness is kept constant, the greater film-to-substrate stiffness ratio will induce a larger deflection, while for the case of fixed total cantilever thickness, the optimal cantilever deflection is independent of the physical parameters of the materials such as Young's modulus and Poisson's ratio.

  20. Reconstructing the distributed force on an atomic force microscope cantilever

    Science.gov (United States)

    Wagner, Ryan; Killgore, Jason

    2017-03-01

    A methodology is developed to reconstruct the force applied to an atomic force microscopy (AFM) cantilever given the shape in which it vibrates. This is accomplished by rewriting Bernoulli–Euler beam theory such that the force on the cantilever is approximated as a linear superposition of the theoretical cantilever eigenmodes. The weighting factors in this summation are calculated from the amplitude and phase measured along the length of the cantilever. The accuracy of the force reconstruction is shown to depend on the frequency at which the measurement is performed, the number of discrete points measured along the length of the cantilever, and the signal-to-noise ratio of the measured signal. In contrast to other AFM force reconstruction techniques, this method can reconstruct the distribution of force applied over the length of the AFM cantilever. However, this method performs poorly for localized forces applied to the cantilever, such as is typical of most tip–sample interaction forces. Proof of concept experiments are performed on an electrostatically excited cantilever and the expected force distribution is recovered. This force reconstruction technique offers previously unavailable insight into the distributed forces experienced by an AFM cantilever.

  1. Imaging using lateral bending modes of atomic force microscope cantilevers

    Science.gov (United States)

    Caron, A.; Rabe, U.; Reinstädtler, M.; Turner, J. A.; Arnold, W.

    2004-12-01

    Using scanning probe techniques, surface properties such as shear stiffness and friction can be measured with a resolution in the nanometer range. The torsional deflection or buckling of atomic force microscope cantilevers has previously been used in order to measure the lateral forces acting on the tip. This letter shows that the flexural vibration modes of cantilevers oscillating in their width direction parallel to the sample surface can also be used for imaging. These lateral cantilever modes exhibit vertical deflection amplitudes if the cantilever is asymmetric in thickness direction, e.g., by a trapezoidal cross section.

  2. An electrochemical-cantilever platform for hybrid sensing applications

    DEFF Research Database (Denmark)

    Fischer, Lee MacKenzie; Dohn, Søren; Boisen, Anja

    2011-01-01

    This work presents a fully-functional, microfabricated electrochemical-cantilever hybrid platform with flow control. A new cantilever chip format is designed, fabricated, and mounted in a custom polymer flow cell. Issues such as leakage and optical/electrical access are addressed, and combined me...... mechanical and electrochemical performance is investigated. Lastly, a cantilever is “defunctionalized” in situ to create a reference cantilever for differential measurements in detection of Cu2+ ions at concentrations of 10 μM and 100 nM....

  3. Resonant Response of Rectangular AFM Cantilever in Liquid

    Institute of Scientific and Technical Information of China (English)

    CHEN Yu-Hang; HUANG Wen-Hao

    2007-01-01

    Dynamic characteristics of atomic force microscopy (AFM) cantilevers can be influenced by their working media.We perform an experimental study on the resonant responses of rectangular AFM cantilevers with different sizes immersed in various viscous fluids. The measured resonance frequencies in liquids are used to validate several theoretical models. Comparison shows the analytical model proposed by Sader [J. Appl. Phys. 84 (1998) 64] can give the best agreement with the experimental results with the maximum relative error nearly 16% for all the cantilevers in different liquids. The ratio between the resonant frequencies in air and water is almost independent of the cantilever length, which is consistent with the theoretical analyses.

  4. Antibody-based protein detection using piezoresistive cantilever arrays

    Science.gov (United States)

    Dauksaite, Vita; Lorentzen, Martin; Besenbacher, Flemming; Kjems, Jørgen

    2007-03-01

    A piezoresistive cantilever array platform with electrical read-out was applied for protein detection using GST (glutathione-S-transferase) and GST antibodies as a model system. Sensing was performed in the static deflection mode under constant flow conditions. The GST antibodies were directly immobilized on the cantilever gold surface by means of free thiol groups. The setup allowed simultaneous deflection measurements with sensor and control-antibody-immobilized reference cantilevers and enabled detection of 1 ng µl-1 (40 nM) of GST protein, which is similar to the sensitivity reported for cantilever sensors using an optical read-out system.

  5. Cantilever Beam Construction Technology%悬浇梁施工工艺

    Institute of Scientific and Technical Information of China (English)

    丁海旭

    2014-01-01

    悬浇梁施工是桥梁施工项目当中的重难点,其施工工艺的特点就是在没有支架的施工场地、大型移动的吊装机械又不适用的情况之下,对较大跨径连续梁桥进行浇筑。在这种施工工艺当中,需要采用悬浇梁施工的工艺方法。%Cantilever beam construction is difficulty of bridge construction projects. The characteristics of the construction process are under no bracket construction site, hoisting mac-hinery large mobile not applicable to the situation, to pours la-rge span continuous beam bridge concrete. During the const-ruction process, we need to use the process of suspension gi-rder construction.

  6. Construction and control technology of the main bridge superstructure of Sutong Bridge

    Institute of Scientific and Technical Information of China (English)

    Zhang Hong; Luo Chenbin; Zhang Yongtao; You Xinpeng

    2009-01-01

    The Sutong Yangtze River Bridge (short as Sutong Bridge) is now the largest span cable-stayed bridge in the world. The construction of the superstructure of the middle bridge covered several stages including erection of the big block girders for the side span, assistant span and tower area, erection of standard girders and closure of the middle span. The big block girders were hoisted by a floating crane, and the standard girders were hoisted by a double crane system on the deck. The pushing assistant method was adopted for the middle span closure construction. Furthermore, key technologies and innovative methods used in the processes of girder erection and cable assemblage in all stages were expatiated systematically. An all-stage self- adaptive geometry control method was used in the construction process. By accurately controlling the unstressed dimensions and shape of all structural components in each step, and realization that the control system and the controlled system adapt to each other, the goal was to make control of the final line shape and inner force of the bridge structure achievable. Two solutions, including GPS based and total station based dynamic geometry monitoring systems, were used to resolve the measure problem under the wide-range of wind-induced vibrations in the long cantilever state. Finally, research on the wind-induced vibration of the superstructure during the construction period was executed. Buffeting response analysis to the longest single and double cantilever states were carried out. The analysis and evaluation of wind resistance safety of the main girders under the longest single cantilever state was made, and corresponding wind resistance measures were suggested. The as-built geometric error and cable force error were controlled in a required design range, and this whole technological achievement can be a benchmark for construction of other large span cable-stayed bridges in the future.

  7. Fabrication of biopolymer cantilevers using nanoimprint lithography

    DEFF Research Database (Denmark)

    Keller, Stephan Sylvest; Feidenhans'l, Nikolaj Agentoft; Fisker-Bødker, Nis

    2011-01-01

    The biodegradable polymer poly(l-lactide) (PLLA) was introduced for the fabrication of micromechanical devices. For this purpose, thin biopolymer films with thickness around 10 μm were spin-coated on silicon substrates. Patterning of microcantilevers is achieved by nanoimprint lithography. A major...... challenge was the high adhesion between PLLA and silicon stamp. Optimized stamp fabrication and the deposition of a 125 nm thick fluorocarbon anti-stiction coating on the PLLA allowed the fabrication of biopolymer cantilevers. Resonance frequency measurements were used to estimate the Young’s modulus...

  8. Experimental and Numerical Study of Damaged Cantilever

    DEFF Research Database (Denmark)

    Rytter, A.; Krawczuk, M.; Kirkegaard, Poul Henning

    2000-01-01

    The introduction of a crack in a steel structure will cause a local change in the stiffness and damping capacity. The change in stiffness will lead to a change of some of the natural frequencies of the structure and a discontinuity in the associated mode shapes. This paper contains a presentation...... of the results from experimental and numerical tests with hollow section cantileves containing fatigue cracks. Two different finite-element (FE) models have been used to estimate the modal parameters numerically. The first FE model consists of beam elements. The second FE model consists of traditional...

  9. Nanoscale microwave microscopy using shielded cantilever probes

    KAUST Repository

    Lai, Keji

    2011-04-21

    Quantitative dielectric and conductivity mapping in the nanoscale is highly desirable for many research disciplines, but difficult to achieve through conventional transport or established microscopy techniques. Taking advantage of the micro-fabrication technology, we have developed cantilever-based near-field microwave probes with shielded structures. Sensitive microwave electronics and finite-element analysis modeling are also utilized for quantitative electrical imaging. The system is fully compatible with atomic force microscope platforms for convenient operation and easy integration of other modes and functions. The microscope is ideal for interdisciplinary research, with demonstrated examples in nano electronics, physics, material science, and biology.

  10. Cantilever deflection measurement and actuation by an nterdigitated transducer

    NARCIS (Netherlands)

    Strambini, E.; Piazza, V.; Pingue, P.; Biasiol, G.; Sorba, L.; Beltram, F.

    2010-01-01

    A scheme that allows all-electrical high-bandwidth readout of a cantilever deflection by means of an integrated interdigitated transducer is presented. The present approach takes advantage of the piezoelectricity of the chosen cantilever substrate material to generate and detect surface-acoustic-wav

  11. Influence of random roughness on cantilever resonance frequency

    NARCIS (Netherlands)

    Ergincan, O.; Palasantzas, G.

    2010-01-01

    In this paper we investigate the influence of random roughness on the oscillation frequency of cantilevers coated with thin film overlayers. First the theory expressions for the roughness-induced frequency shift are derived using the cantilever equation of motion. Subsequently it is shown that the r

  12. Interlaboratory round robin on cantilever calibration for AFM force spectroscopy.

    Science.gov (United States)

    te Riet, Joost; Katan, Allard J; Rankl, Christian; Stahl, Stefan W; van Buul, Arend M; Phang, In Yee; Gomez-Casado, Alberto; Schön, Peter; Gerritsen, Jan W; Cambi, Alessandra; Rowan, Alan E; Vancso, G Julius; Jonkheijm, Pascal; Huskens, Jurriaan; Oosterkamp, Tjerk H; Gaub, Hermann; Hinterdorfer, Peter; Figdor, Carl G; Speller, Sylvia

    2011-12-01

    Single-molecule force spectroscopy studies performed by Atomic Force Microscopes (AFMs) strongly rely on accurately determined cantilever spring constants. Hence, to calibrate cantilevers, a reliable calibration protocol is essential. Although the thermal noise method and the direct Sader method are frequently used for cantilever calibration, there is no consensus on the optimal calibration of soft and V-shaped cantilevers, especially those used in force spectroscopy. Therefore, in this study we aimed at establishing a commonly accepted approach to accurately calibrate compliant and V-shaped cantilevers. In a round robin experiment involving eight different laboratories we compared the thermal noise and the Sader method on ten commercial and custom-built AFMs. We found that spring constants of both rectangular and V-shaped cantilevers can accurately be determined with both methods, although the Sader method proved to be superior. Furthermore, we observed that simultaneous application of both methods on an AFM proved an accurate consistency check of the instrument and thus provides optimal and highly reproducible calibration. To illustrate the importance of optimal calibration, we show that for biological force spectroscopy studies, an erroneously calibrated cantilever can significantly affect the derived (bio)physical parameters. Taken together, our findings demonstrated that with the pre-established protocol described reliable spring constants can be obtained for different types of cantilevers.

  13. Hysteresis of the resonance frequency of magnetostrictive bending cantilevers

    Science.gov (United States)

    Löffler, Michael; Kremer, Ramona; Sutor, Alexander; Lerch, Reinhard

    2015-05-01

    Magnetostrictive bending cantilevers are applicable for wirelessly measuring physical quantities such as pressure and strain. Exploiting the ΔE-effect, the resonance frequency of the cantilevers is shifted because of a change in the magnetic biasing field. The biasing field, in turn, depends on the applied pressure or strain, respectively. With a view to the application as a reliable sensor, maximum sensitivity but minimum hysteresis in the biasing field/resonance frequency dependence is preferred. In this contribution, monomorph bending cantilevers fabricated using magnetostrictive Fe49Co49V2 and Metglas 2605SA1 are investigated regarding their applicability for future sensors. For this purpose, the biasing field-dependent polarization of the magnetostrictive materials and bending of the cantilevers are determined. Furthermore, a setup to magnetically bias the cantilevers and determine the bending resonance frequency is presented. Here, the resonance frequency is identified by measuring the impulse response employing a laser Doppler vibrometer. The measurement results reveal that cantilevers made of Fe49Co49V2 possess a distinct hysteretic behaviour at low magnetic biasing field magnitudes. This is ascribed to the polarization and bending hysteresis. Cantilevers fabricated using Metglas 2605SA1 feature a lower resonance frequency shift compared to cantilevers with Fe49Co49V2, which would result in a lower sensitivity of the sensor. However, their resonance frequency hysteresis is almost negligible.

  14. Development of a microfabricated electrochemical-cantilever hybrid platform

    DEFF Research Database (Denmark)

    Fischer, Lee MacKenzie; Pedersen, Christoffer; Elkjær, Karl;

    2011-01-01

    The design and fabrication of a combined electrochemical-cantilever microfluidic system is described. A chip integrating cantilevers with electrodes into a microchannel is presented with the accompanying polymer flow cell. Issues such as electrical and fluid connections are addressed, electromech...

  15. Cantilever surface stress sensors with single-crystalline silicon piezoresistors

    DEFF Research Database (Denmark)

    Rasmussen, Peter Andreas; Hansen, Ole; Boisen, Anja

    2005-01-01

    on cantilever sensors with integrated piezoresistive readout, that one finds between typical atomic force microscopy measurements and the surface stress sensors used in, e.g., biochemical measurements. We have simulated the response from piezoresistive cantilevers as a function of resistor type and placement...

  16. Interlaboratory round robin on cantilever calibration for AFM force spectroscopy.

    NARCIS (Netherlands)

    Riet, J. te; Katan, A.J.; Rankl, C.; Stahl, S.W.; Buul, A.M. van; Phang, I.Y.; Gomez-Casado, A.; Schon, P.; Gerritsen, J.W.; Cambi, A.; Rowan, A.E.; Vancso, G.J.; Jonkheijm, P.; Huskens, J.; Oosterkamp, T.H.; Gaub, H.; Hinterdorfer, P.; Figdor, C.G.; Speller, S.

    2011-01-01

    Single-molecule force spectroscopy studies performed by Atomic Force Microscopes (AFMs) strongly rely on accurately determined cantilever spring constants. Hence, to calibrate cantilevers, a reliable calibration protocol is essential. Although the thermal noise method and the direct Sader method are

  17. Novel resonant cantilever mass change detection and resonant frequency tuning

    DEFF Research Database (Denmark)

    Grigorov, Alexander; Boisen, Anja

    2005-01-01

    This paper reports a novel way to detect the resonant frequency of an electro-thermally actuated cantilever sensor that we have previously reported, in order to perform mass detection by resonant frequency shift detection. The device is based on monitoring the rupture of a clamped cantilever stru...

  18. Development of Electrochemical Cantilever Sensors for DNA Applications

    DEFF Research Database (Denmark)

    Quan, Xueling; Heiskanen, Arto; Yi, Sun;

    2013-01-01

    In this work, we develop a generic DNA based sensing platform used for characterizing surface functionalization and detecting DNA hybridization. Silicon nitride cantilever sensors are fabricated with an integrated three-electrode system and integrated in a microfluidic chip. Cantilevers with gold...

  19. Serial weighting of micro-objects with resonant microchanneled cantilevers

    Science.gov (United States)

    Ossola, Dario; Dörig, Pablo; Vörös, János; Zambelli, Tomaso; Vassalli, Massimo

    2016-10-01

    Atomic force microscopy (AFM) cantilevers have proven to be very effective mass sensors. The attachment of a small mass to a vibrating cantilever produces a resonance frequency shift that can be monitored, providing the ability to measure mass changes down to a few molecules resolution. Nevertheless, the lack of a practical method to handle the catch and release process required for dynamic weighting of microobjects strongly hindered the application of the technology beyond proof of concept measurements. Here, a method is proposed in which FluidFM hollow cantilevers are exploited to overcome the standard limitations of AFM-based mass sensors, providing high throughput single object weighting with picogram accuracy. The extension of the dynamic models of AFM cantilevers to hollow cantilevers was discussed and the effectiveness of mass weighting in air was validated on test samples.

  20. Optical racetrack resonator transduction of nanomechanical cantilevers.

    Science.gov (United States)

    Sauer, V T K; Diao, Z; Freeman, M R; Hiebert, W K

    2014-02-07

    Optomechanical transduction has demonstrated its supremacy in probing nanomechanical displacements. In order to apply nano-optomechanical systems (NOMS) as force and mass sensors, knowledge about the transduction responsivity (i.e. the change in measured optical transmission with nanomechanical displacement) and its tradeoffs with system design is paramount. We compare the measured responsivities of NOMS devices with varying length, optomechanical coupling strength gom, and optical cavity properties. Cantilever beams 1.5 to 5 μm long are fabricated 70 to 160 nm from a racetrack resonator optical cavity and their thermomechanical (TM) noise signals are measured. We derive a generic expression for the transduction responsivity of the NOMS in terms of optical and mechanical system parameters such as finesse, optomechanical coupling constant, and interaction length. The form of the expression holds direct insight as to how these parameters affect the responsivity. With this expression, we obtain the optomechanical coupling constants using only measurements of the TM noise power spectra and optical cavity transmission slopes. All optical pump/probe operation is also demonstrated in our side-coupled cantilever-racetrack NOMS. Finally, to assess potential operation in a gas sensing environment, the TM noise signal of a device is measured at atmospheric pressure.

  1. Myocardial Bridging

    Directory of Open Access Journals (Sweden)

    Shi-Min Yuan

    2016-02-01

    Full Text Available Abstract Myocardial bridging is rare. Myocardial bridges are most commonly localized in the middle segment of the left anterior descending coronary artery. The anatomic features of the bridges vary significantly. Alterations of the endothelial morphology and the vasoactive agents impact on the progression of atherosclerosis of myocardial bridging. Patients may present with chest pain, myocardial infarction, arrhythmia and even sudden death. Patients who respond poorly to the medical treatment with β-blockers warrant a surgical intervention. Myotomy is a preferred surgical procedure for the symptomatic patients. Coronary stent deployment has been in limited use due to the unsatisfactory long-term results.

  2. In-situ piezoresponse force microscopy cantilever mode shape profiling

    Energy Technology Data Exchange (ETDEWEB)

    Proksch, R., E-mail: roger.proksch@oxinst.com [Asylum Research, an Oxford Instruments Company, Santa Barbara, California 93117 (United States)

    2015-08-21

    The frequency-dependent amplitude and phase in piezoresponse force microscopy (PFM) measurements are shown to be a consequence of the Euler-Bernoulli (EB) dynamics of atomic force microscope (AFM) cantilever beams used to make the measurements. Changes in the cantilever mode shape as a function of changes in the boundary conditions determine the sensitivity of cantilevers to forces between the tip and the sample. Conventional PFM and AFM measurements are made with the motion of the cantilever measured at one optical beam detector (OBD) spot location. A single OBD spot location provides a limited picture of the total cantilever motion, and in fact, experimentally observed cantilever amplitude and phase are shown to be strongly dependent on the OBD spot position for many measurements. In this work, the commonly observed frequency dependence of PFM response is explained through experimental measurements and analytic theoretical EB modeling of the PFM response as a function of both frequency and OBD spot location on a periodically poled lithium niobate sample. One notable conclusion is that a common choice of OBD spot location—at or near the tip of the cantilever—is particularly vulnerable to frequency dependent amplitude and phase variations stemming from dynamics of the cantilever sensor rather than from the piezoresponse of the sample.

  3. Quantitative Boundary Support Characterization for Cantilever MEMS

    Directory of Open Access Journals (Sweden)

    Ion Stiharu

    2007-10-01

    Full Text Available Microfabrication limitations are of concern especially for suspended Micro-Electro-Mechanical-Systems (MEMS microstructures such as cantilevers. The static anddynamic qualities of such microscale devices are directly related to the invariant and variantproperties of the microsystem. Among the invariant properties, microfabrication limitationscan be quantified only after the fabrication of the device through testing. However, MEMSare batch fabricated in large numbers where individual testing is neither possible nor costeffective. Hence, a suitable test algorithm needs to be developed where the test resultsobtained for a few devices can be applied to the whole fabrication batch, and also to thefoundry process in general. In this regard, this paper proposes a method to test MEMScantilevers under variant electro-thermal influences in order to quantify the effectiveboundary support condition obtained for a foundry process. A non-contact optical sensingapproach is employed for the dynamic testing. The Rayleigh-Ritz energy method usingboundary characteristic orthogonal polynomials is employed for the modeling andtheoretical analysis.

  4. Polymer cantilever platform for dielectrophoretic assembly of carbon nanotubes

    DEFF Research Database (Denmark)

    Johansson, Alicia; Calleja, M.; Dimaki, Maria;

    2004-01-01

    A polymer cantilever platform for dielectrophoretic assembly of carbon nanotubes has been designed and realized. Multi-walled carbon nanotubes from aqueous solution have been assembled between two metal electrodes that are separated by 2 mu m and embedded in the polymer cantilever. The entire chip......, except for the metallic electrodes and wiring, was fabricated in the photoresist SU-8. SU-8 allows for an inexpensive, flexible and fast fabrication method, and the cantilever platform provides a hydrophobic surface that should be well suited for nanotube assembly. The device can be integrated in a micro...

  5. Characterization of magnetically actuated resonant cantilevers in viscous fluids

    Science.gov (United States)

    Vančura, Cyril; Lichtenberg, Jan; Hierlemann, Andreas; Josse, Fabien

    2005-10-01

    The vibration behavior of magnetically actuated resonant microcantilevers immersed in viscous fluids has been studied. A dependence of the resonance frequency and the quality factor (Q factor) on the fluid properties, such as density and viscosity and on the cantilever geometry is described. Various cantilever geometries are analyzed in pure water and glycerol solutions, and the results are explained in terms of the added displaced fluid mass and the fluid damping force for both the resonance frequency and the quality factor. An in-depth knowledge and understanding of such systems is necessary when analyzing resonant cantilevers as biochemical sensors in liquid environments.

  6. Voltage generation of piezoelectric cantilevers by laser heating.

    Science.gov (United States)

    Hsieh, Chun-Yi; Liu, Wei-Hung; Chen, Yang-Fang; Shih, Wan Y; Gao, Xiaotong; Shih, Wei-Heng

    2012-11-15

    Converting ambient thermal energy into electricity is of great interest in harvesting energy from the environment. Piezoelectric cantilevers have previously been shown to be an effective biosensor and a tool for elasticity mapping. Here we show that a single piezoelectric (lead-zirconate titanate (PZT)) layer cantilever can be used to convert heat to electricity through pyroelectric effect. Furthermore, piezoelectric-metal (PZT-Ti) bi-layer cantilever showed an enhanced induced voltage over the single PZT layer alone due to the additional piezoelectric effect. This type of device can be a way for converting heat energy into electricity.

  7. Single microparticles mass measurement using an AFM cantilever resonator

    CERN Document Server

    Mauro, Marco; Ferrini, Gianluca; Puglisi, Roberto; Balduzzi, Donatella; Galli, Andrea

    2014-01-01

    In this work is presented a microbalance for single microparticle sensing based on resonating AFM cantilever. The variation of the resonator eigenfrequency is related to the particle mass positioned at the free apex of the cantilever. An all-digital phase locked loop (PLL) control system is developed to detect the variations in cantilever eigenfrequency. Two particle populations of different materials are used in the experimental test, demonstrating a mass sensitivity of 15 Hz/pg in ambient conditions. Thereby it is validated the possibility of developing an inexpensive, portable and sensitive microbalance for point-mass sensing.

  8. Energy harvesting from radio frequency propagation using piezoelectric cantilevers

    KAUST Repository

    Al Ahmad, Mahmoud

    2012-02-01

    This work reports an induced strain in a piezoelectric cantilever due to radio frequency signal propagation. The piezoelectric actuator is coupled to radio frequency (RF) line through a gap of 0.25 mm. When a voltage signal of 10 Vpp propagates in the line it sets an alternating current in the actuator electrodes. This flowing current drives the piezoelectric cantilever to mechanical movement, especially when the frequency of the RF signal matches the mechanical resonant frequency of the cantilever. Output voltage signals versus frequency for both mechanical vibrational and RF signal excitations have been measured using different loads.© 2011 Elsevier Ltd. All rights reserved.

  9. Scanned-cantilever atomic force microscope with large scanning range

    Institute of Scientific and Technical Information of China (English)

    Jintao Yang; Wendong Xu

    2006-01-01

    A scanned-cantilever atomic force microscope (AFM) with large scanning range is proposed, which adopts a new design named laser spot tracking. The scanned-cantilever AFM uses the separate flexure x-y scanner and z scanner instead of the conventional piezoelectric tube scanner. The closed-loop control and integrated capacitive sensors of these scanners can insure that the images of samples have excellent linearity and stability. According to the experimental results, the scanned-cantilever AFM can realize maximal 100 × 100 (μm) scanning range, and 1-nm resolution in z direction, which can meet the requirements of large scale sample testing.

  10. Bridge Management Systems

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper bridge management systems are discussed with special emphasis on management systems for reinforced concrete bridges. Management systems for prestressed concrete bridges, steel bridges, or composite bridges can be developed in a similar way....

  11. Integrated MEMS/NEMS Resonant Cantilevers for Ultrasensitive Biological Detection

    Directory of Open Access Journals (Sweden)

    Xinxin Li

    2009-01-01

    Full Text Available The paper reviews the recent researches implemented in Chinese Academy of Sciences, with achievements on integrated resonant microcantilever sensors. In the resonant cantilevers, the self-sensing elements and resonance exciting elements are both top-down integrated with silicon micromachining techniques. Quite a lot of effort is focused on optimization of the resonance mode and sensing structure for improvement of sensitivity. On the other hand, to enable the micro-cantilevers specifically sensitive to bio/chemical molecules, sensing materials are developed and modified on the cantilever surface with a self-assembled monolayer (SAM based bottom-up construction and surface functionalization. To improve the selectivity of the sensors and depress environmental noise, multiple and localized surface modifications are developed. The achieved volume production capability and satisfactory detecting resolution to trace-level biological antigen of alpha-fetoprotein (AFP give the micro-cantilever sensors a great promise for rapid and high-resoluble detection.

  12. Cantilever-Based Microwave Biosensors: Analysis, Designs and Optimizations

    DEFF Research Database (Denmark)

    Jiang, Chenhui; Johansen, Tom Keinicke; Jónasson, Sævar Þór;

    2011-01-01

    This paper presents a novel microwave readout scheme for measuring deflection of cantilevers in nanometer range. The cantilever deflection can be sensed by the variation of transmission levels or resonant frequencies of microwave signals. The sensitivity of the cantilever biosensor based on LC...... resonators is at first theoretically analyzed. A LC resonator based biosensor with beams is designed and optimized by using 3D electromagnetic (EM) simulations, where the beam is a typical variation of cantilevers. The sensitivity of the lossless biosensor is predicted as 4.6MHz/nm. The 3-dB bandwidths...... of the resonances are narrowed for improving the resolution of distinguishing resonances by reducing conductive loss of electrodes. The lossy biosensor can achieve the highest sensitivity as 5.6 MHz/nm and narrowest 3-dB bandwidth as 5 GHz....

  13. Study on electrothermally actuated cantilever array for nanolithography

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Nanolithography is a patterning technique for the fabrication of nano-scale structures.A promising method of nanolithography known as scanning probe lithography has particularly extensive applications for its high resolution,high reliability,and simple operation.In this paper,a novel electrothermally actuated cantilever with integrated heater,thermal conductor and actuator for scanning probe lithography is proposed.Cantilevers are designed in an 8×4 array.Analytical models are presented to simulate the temperature distribution,deflection and thermal crosstalk of the cantilever array.This structure is successfully fabricated.It is demonstrated that this structure can produce a tip deflection of 16.9 μm at an actuation current of 5.5 mA and the thermal crosstalk between the cantilevers is neglected.

  14. Resonance frequency shift of strongly heated micro-cantilevers

    CERN Document Server

    Sandoval, Felipe Aguilar; Bertin, Éric; Bellon, Ludovic

    2015-01-01

    In optical detection setups to measure the deflection of micro-cantilevers, part of the sensing light is absorbed, heating the mechanical probe. We present experimental evidences of a frequency shift of the resonant modes of a cantilever when the light power of the optical measurement set-up is increased. This frequency shift is a signature of the temperature rise, and presents a dependence on the mode number. An analytical model is derived to take into account the temperature profile along the cantilever, it shows that the frequency shifts are given by an average of the profile weighted by the local curvature for each resonant mode. We apply this framework to measurements in vacuum and demonstrate that huge temperatures can be reached with moderate light intensities: a thousand {\\textdegree}C with little more than 10 mW. We finally present some insight into the physical phenomena when the cantilever is in air instead of vacuum.

  15. Improved Sensitivity MEMS Cantilever Sensor for Terahertz Photoacoustic Spectroscopy.

    Science.gov (United States)

    Coutu, Ronald A; Medvedev, Ivan R; Petkie, Douglas T

    2016-01-01

    In this paper, a microelectromechanical system (MEMS) cantilever sensor was designed, modeled and fabricated to measure the terahertz (THz) radiation induced photoacoustic (PA) response of gases under low vacuum conditions. This work vastly improves cantilever sensitivity over previous efforts, by reducing internal beam stresses, minimizing out of plane beam curvature and optimizing beam damping. In addition, fabrication yield was improved by approximately 50% by filleting the cantilever's anchor and free end to help reduce high stress areas that occurred during device fabrication and processing. All of the cantilever sensors were fabricated using silicon-on-insulator (SOI) wafers and tested in a custom built, low-volume, vacuum chamber. The resulting cantilever sensors exhibited improved signal to noise ratios, sensitivities and normalized noise equivalent absorption (NNEA) coefficients of approximately 4.28 × 10(-10) cm(-1)·WHz(-1/2). This reported NNEA represents approximately a 70% improvement over previously fabricated and tested SOI cantilever sensors for THz PA spectroscopy.

  16. Design and optimization of cantilevered magnetostrictive film-substrate microactuator

    Institute of Scientific and Technical Information of China (English)

    B.; Narsu; YUN; GuoHong; RONG; JianHong

    2007-01-01

    The exact solution for the bending problem of a free-end point loaded films-ubstrate cantilever with arbitrary film-to-substrate thickness ratio is obtained by using the basic mechanical equilibrium equation. And then the problem of design and optimization for microactuator buildup of film-substrate cantilever is discussed by taking into account the effect of geometrical and physical parameters of the cantilever components. Furthermore, the optimal condition for actuator application is presented and some theoretical problems are clarified. The results show that, in general, the greater the film-to-substrate thickness ratio, the higher the ability of taking load, namely the larger the exerted force of the cantilever when the thickness of substrate is kept constant. When the total thickness of the cantilever is kept constant, however, the free-end exerted force will experience a maximum and this maximum value of the exerted force will decrease with the increasing film-to-sub- strate stiffness ratio. Meanwhile, the optimal thickness ratio corresponding to this maximum exerted force also decreases with the increasing stiffness ratio. Whether for the cases of fixed substrate or fixed total thickness, the influence of Poisson's ratio of two cantilever components on the exerted force is remarkable, and should not be neglected.

  17. National Bridge Inventory (NBI) Bridges

    Data.gov (United States)

    Department of Homeland Security — The NBI is a collection of information (database) describing the more than 600,000 of the Nation's bridges located on public roads, including Interstate Highways,...

  18. Measurement of Mechanical Properties of Cantilever Shaped Materials

    Directory of Open Access Journals (Sweden)

    Thomas Thundat

    2008-05-01

    Full Text Available Microcantilevers were first introduced as imaging probes in Atomic Force Microscopy (AFM due to their extremely high sensitivity in measuring surface forces. The versatility of these probes, however, allows the sensing and measurement of a host of mechanical properties of various materials. Sensor parameters such as resonance frequency, quality factor, amplitude of vibration and bending due to a differential stress can all be simultaneously determined for a cantilever. When measuring the mechanical properties of materials, identifying and discerning the most influential parameters responsible for the observed changes in the cantilever response are important. We will, therefore, discuss the effects of various force fields such as those induced by mass loading, residual stress, internal friction of the material, and other changes in the mechanical properties of the microcantilevers. Methods to measure variations in temperature, pressure, or molecular adsorption of water molecules are also discussed. Often these effects occur simultaneously, increasing the number of parameters that need to be concurrently measured to ensure the reliability of the sensors. We therefore systematically investigate the geometric and environmental effects on cantilever measurements including the chemical nature of the underlying interactions. To address the geometric effects we have considered cantilevers with a rectangular or circular cross section. The chemical nature is addressed by using cantilevers fabricated with metals and/or dielectrics. Selective chemical etching, swelling or changes in Young’s modulus of the surface were investigated by means of polymeric and inorganic coatings. Finally to address the effect of the environment in which the cantilever operates, the Knudsen number was determined to characterize the molecule-cantilever collisions. Also bimaterial cantilevers with high thermal sensitivity were used to discern the effect of temperature

  19. Resonance Based Micromechanical Cantilever for Gas Sensing

    Directory of Open Access Journals (Sweden)

    Subhashini. S

    2013-04-01

    Full Text Available Our world is facing some drastic changes in the climatic conditions due to the heating effect caused by various greenhouse gases. The most harmful gas among them is Carbon dioxide and is increasing at anuncontrolled rate.This paper aims in finding out the quantity of the major polluting gas carbon dioxide. The gravimetric sensor works by adsorbing the CO2 molecules on ZnO sensing layer, which alters the overall mass of the sensor. The mechanical structure is a cantilever, having its own resonant frequency. To selectively adsorbCO2 molecules from the mixture of gaseous molecules, ZnO at a specific temperature is used. As the gas molecules are adsorbed the mass increases and hence there is a change in resonant frequency. This change in frequency gives the measure of the quantity of CO2 molecules present in that environment. The major expected advantage of this technique would be the repeatability of the sensor that is used. This Quantitative analysis of CO2 would be helpful for mankind by alerting them about the environment in which they work,by proper conditioning and networking

  20. Piezoresistive cantilever force-clamp system

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung-Jin; Petzold, Bryan C.; Pruitt, Beth L. [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Goodman, Miriam B. [Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305 (United States)

    2011-04-15

    We present a microelectromechanical device-based tool, namely, a force-clamp system that sets or ''clamps'' the scaled force and can apply designed loading profiles (e.g., constant, sinusoidal) of a desired magnitude. The system implements a piezoresistive cantilever as a force sensor and the built-in capacitive sensor of a piezoelectric actuator as a displacement sensor, such that sample indentation depth can be directly calculated from the force and displacement signals. A programmable real-time controller operating at 100 kHz feedback calculates the driving voltage of the actuator. The system has two distinct modes: a force-clamp mode that controls the force applied to a sample and a displacement-clamp mode that controls the moving distance of the actuator. We demonstrate that the system has a large dynamic range (sub-nN up to tens of {mu}N force and nm up to tens of {mu}m displacement) in both air and water, and excellent dynamic response (fast response time, <2 ms and large bandwidth, 1 Hz up to 1 kHz). In addition, the system has been specifically designed to be integrated with other instruments such as a microscope with patch-clamp electronics. We demonstrate the capabilities of the system by using it to calibrate the stiffness and sensitivity of an electrostatic actuator and to measure the mechanics of a living, freely moving Caenorhabditis elegans nematode.

  1. Piezoelectric energy harvesting from traffic-induced bridge vibrations

    Science.gov (United States)

    Peigney, Michaël; Siegert, Dominique

    2013-09-01

    This paper focuses on energy harvesting from traffic-induced vibrations in bridges. Using a pre-stressed concrete highway bridge as a case study, in situ vibration measurements are presented and analysed. From these results, a prototype of a cantilever piezoelectric harvester is designed, tested and modelled. Even though the considered bridge vibrations are characterized by small amplitude and a low frequency (i.e. below 15 Hz), it is shown that mean power of the order of 0.03 mW can be produced, with a controlled voltage between 1.8 and 3.6 V. A simple model is proposed for theoretical prediction of the delivered power in terms of traffic intensity. This model shows good agreement with the experimental results and leads to a simple but effective design rule for piezoelectric harvesters to be used on bridges.

  2. High resolved velocity measurements using Laser Cantilever Anemometry

    Science.gov (United States)

    Puczylowski, Jaroslaw; Hölling, Michael; Peinke, Joachim

    2016-11-01

    We have developed a new anemometer, namely the 2d-LCA (2d-Laser-Cantilever-Anemometer), that is capable of performing high resolved velocity measurements in fluids. The anemometer uses a micostructured cantilever made of silicon as a sensing element. The specific shape and the small dimensions (about 150µm) of the cantilever allow for precise measurements of two velocity component at a temporal resolution of about 150kHz. The angular acceptance range is 180° in total. The 2d-LCA is a simple to use alternative to x-wires and can be used in many areas of operation including measurements in liquids or in particle-laden flows. Unlike hot-wires, the resolution power of the 2d-LCA does not decrease with increasing flow velocity, making it particularly suitable for measurements in high-speed flows. In the recent past new cantilever designs were implemented with the goal to further improve the angular resolution and increase the stability. In addition, we have designed more robust cantilevers for measurements in rough environments such as offshore areas. Successful comparative measurements with hot-wires have been carried out in order to assess the performance of the 2d-LCA.

  3. Critical caving erosion width for cantilever failures of river bank

    Institute of Scientific and Technical Information of China (English)

    Yangui Wang; Shangfu Kuang; Jialin Su

    2016-01-01

    The cantilever failure is one of the typical bank failures, in which the lateral caving erosion at the bottom of the bank plays an important role. When the caving erosion width is larger than a certain value, the cantilever failures such as shear, toppling and stress failures may occur. In order to understand the condition of the cantilever failure, the collapse mechanisms of the cantilever failures are studied based on the bank stability theory and flume experiment. According to the bank stability equation with the lateral erosion, the critical caving erosion width (CCEW) formulas for the shear and toppling failures of simple slope bank were derived in this paper. The formulas show that the CCEW increases as the overhanging soil thickness and soil cohesion increase, and decreases as the crack depth on the bank surface and the slope angle of the bank increase. And these formulas were tested with experimental data, which shows the predicted values are good agreement with experimental data. The paper reveals a quantitative expression on the process of the river cantilever failure.

  4. Efficiency Enhancement of a Cantilever-Based Vibration Energy Harvester

    Directory of Open Access Journals (Sweden)

    Ali E. Kubba

    2013-12-01

    Full Text Available Extracting energy from ambient vibration to power wireless sensor nodes has been an attractive area of research, particularly in the automotive monitoring field. This article reports the design, analysis and testing of a vibration energy harvesting device based on a miniature asymmetric air-spaced cantilever. The developed design offers high power density, and delivers electric power that is sufficient to support most wireless sensor nodes for structural health monitoring (SHM applications. The optimized design underwent three evolutionary steps, starting from a simple cantilever design, going through an air-spaced cantilever, and ending up with an optimized air-spaced geometry with boosted power density level. Finite Element Analysis (FEA was used as an initial tool to compare the three geometries’ stiffness (K, output open-circuit voltage (Vave, and average normal strain in the piezoelectric transducer (εave that directly affect its output voltage. Experimental tests were also carried out in order to examine the energy harvesting level in each of the three designs. The experimental results show how to boost the power output level in a thin air-spaced cantilever beam for energy within the same space envelope. The developed thin air-spaced cantilever (8.37 cm3, has a maximum power output of 2.05 mW (H = 29.29 μJ/cycle.

  5. Improved Sensitivity MEMS Cantilever Sensor for Terahertz Photoacoustic Spectroscopy

    Directory of Open Access Journals (Sweden)

    Ronald A. Coutu

    2016-02-01

    Full Text Available In this paper, a microelectromechanical system (MEMS cantilever sensor was designed, modeled and fabricated to measure the terahertz (THz radiation induced photoacoustic (PA response of gases under low vacuum conditions. This work vastly improves cantilever sensitivity over previous efforts, by reducing internal beam stresses, minimizing out of plane beam curvature and optimizing beam damping. In addition, fabrication yield was improved by approximately 50% by filleting the cantilever’s anchor and free end to help reduce high stress areas that occurred during device fabrication and processing. All of the cantilever sensors were fabricated using silicon-on-insulator (SOI wafers and tested in a custom built, low-volume, vacuum chamber. The resulting cantilever sensors exhibited improved signal to noise ratios, sensitivities and normalized noise equivalent absorption (NNEA coefficients of approximately 4.28 × 10−10 cm−1·WHz−1/2. This reported NNEA represents approximately a 70% improvement over previously fabricated and tested SOI cantilever sensors for THz PA spectroscopy.

  6. Nonlinear resonances of a single-wall carbon nanotube cantilever

    Science.gov (United States)

    Kim, I. K.; Lee, S. I.

    2015-03-01

    The dynamics of an electrostatically actuated carbon nanotube (CNT) cantilever are discussed by theoretical and numerical approaches. Electrostatic and intermolecular forces between the single-walled CNT and a graphene electrode are considered. The CNT cantilever is analyzed by the Euler-Bernoulli beam theory, including its geometric and inertial nonlinearities, and a one-mode projection based on the Galerkin approximation and numerical integration. Static pull-in and pull-out behaviors are adequately represented by an asymmetric two-well potential with the total potential energy consisting of the CNT elastic energy, electrostatic energy, and the Lennard-Jones potential energy. Nonlinear dynamics of the cantilever are simulated under DC and AC voltage excitations and examined in the frequency and time domains. Under AC-only excitation, a superharmonic resonance of order 2 occurs near half of the primary frequency. Under both DC and AC loads, the cantilever exhibits linear and nonlinear primary and secondary resonances depending on the strength of the excitation voltages. In addition, the cantilever has dynamic instabilities such as periodic or chaotic tapping motions, with a variation of excitation frequency at the resonance branches. High electrostatic excitation leads to complex nonlinear responses such as softening, multiple stability changes at saddle nodes, or period-doubling bifurcation points in the primary and secondary resonance branches.

  7. Bridged graphite oxide materials

    Science.gov (United States)

    Herrera-Alonso, Margarita (Inventor); McAllister, Michael J. (Inventor); Aksay, Ilhan A. (Inventor); Prud'homme, Robert K. (Inventor)

    2010-01-01

    Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.

  8. On the electromechanical modelling of a resonating nano-cantilever-based transducer

    DEFF Research Database (Denmark)

    Teva, J.; Abadal, G.; Davis, Zachary James;

    2004-01-01

    An electromechanical model for a transducer based on a lateral resonating cantilever is described. The on-plane vibrations of the cantilever are excited electrostatically by applying DC and AC voltages from a driver electrode placed closely parallel to the cantilever. The model predicts the stati....... Both the static and dynamic predictions have been validated experimentally by measuring the deflection of the cantilever by means of an optical microscope. (C) 2004 Elsevier B.V. All rights reserved....

  9. MEMS Cantilever Sensor for THz Photoacoustic Chemical Sensing and Spectroscopy

    Science.gov (United States)

    2013-12-26

    niobate (LiNbO3), sodium potassium niobate ((K,Na)NbO3), and polyvinylidene fluoride (PVDF). Lead zirconate titanate, commonly referred to as PZT is...The sensor used was a mirrored 25 µm thick Mylar droplet shaped pellicle cantilever which was 13 mm long, 2.5 mm wide at the tip, with a narrower...C2H2) mixture in a helium dilution [84]. The cantilever used was 1 μm thick, 500 μm long, and 100 μm wide, which was positioned over a 1.5 mm

  10. Optimization of sensitivity and noise in piezoresistive cantilevers

    DEFF Research Database (Denmark)

    Yu, Xiaomei; Thaysen, Jacob; Hansen, Ole;

    2002-01-01

    In this article, the sensitivity and the noise of piezoresistive cantilevers were systematically investigated with respect to the piezoresistor geometry, the piezoresistive materials, the doping dose, the annealing temperature, and the operating biased voltage. With the noise optimization results......, dimension optimized array cantilevers were designed and fabricated by using single-crystal silicon, low-pressure chemical-vapor deposition (LPCVD) amorphous silicon and microcrystalline silicon as piezoresistive layers. Measurement results have shown that the smallest Hooge factor (alpha) was 3.2x10...

  11. Self-mixing interferometry in VCSELs for nanomechanical cantilever sensing

    DEFF Research Database (Denmark)

    Larsson, David; Greve, Anders; Hvam, Jørn Märcher;

    2009-01-01

    We have investigated optical read-out of uncoated polymer micrometer-sized cantilever sensors by self-mixing interference in VCSELs for single-molecule gas sensing. A resolution ~0.2 nm is measured, which is much better than current methods.......We have investigated optical read-out of uncoated polymer micrometer-sized cantilever sensors by self-mixing interference in VCSELs for single-molecule gas sensing. A resolution ~0.2 nm is measured, which is much better than current methods....

  12. Optimized Optomechanical Micro-Cantilever Array for Uncooled Infrared Imaging

    Institute of Scientific and Technical Information of China (English)

    DONG Feng-Liang; ZHANG Qing-Chuan; CHEN Da-Peng; MIAO Zheng-Yu; XIONG Zhi-Ming; GUO Zhe-Ying; LI Chao-Bo; JIAO Bin-Bin; WU Xiao-Ping

    2007-01-01

    We present a new substrate-free bimaterial cantilever array made of SiNx and Au for an uncooled microoptomechanical infrared imaging device.Each cantilever element has an optimized deformation magnification structure.A 160×160 array with a 120μm×120μm pitch is fabricared and an optical readout is used to collectively measure deflections of all microcantilevers in the array.Tharmal images of room-temperature objects with higher spatial resolution have been obtained and the noise-equivalent temperature difference of the fabricated focal plane arrays is giyen statistically and is measured to be about 270mK.

  13. Cantilever based mass sensor with hard contact readout

    DEFF Research Database (Denmark)

    Dohn, Søren; Hansen, Ole; Boisen, Anja

    2006-01-01

    We present a method for microcantilever resonant frequency detection. We measure the direct current from an intermittent contact once every vibration cycle between the conducting cantilever and a counterelectrode at a low bias voltage with respect to the cantilever, while the excitation frequency...... and amplitude are varied. The result is an almost "digital" detection of the resonant frequency. A relative frequency resolution Delta f/f of 1/80 000 with high signal to noise ratio in ambient conditions is demonstrated. The detection method can be applied to portable sensor systems with very high frequency...

  14. Ingestión accidental de prótesis dental fija (cantilever en paciente con historia de carcinoma de colon Accidental swallowing of fixed denture (cantilever in a patient with history of colon cancer

    Directory of Open Access Journals (Sweden)

    G.M. Fonseca

    2011-12-01

    Full Text Available Se presenta un caso de ingestión accidental de un puente de tipo cantilever metalocerámico de tres unidades en un paciente masculino de 51 años con historia de remoción quirúrgica de carcinoma colorrectal y colostomía provisoria (ano contranatura para recuperación intestinal cuatro años antes. Aun cuando la naturaleza del objeto ingerido y las condiciones patológicas previas intestinales ponderan una conducta quirúrgica de remoción preventiva, dado el carácter asintomático y el control radiográfico del desplazamiento normal del objeto durante las primeras 24 horas, se optó por una conducta expectante que se resolvió finalmente con la excreción espontánea del mismo. Si bien la rehabilitación protésica fija debería brindar seguridad y estabilidad, un diseño sesgado del puente (indicación errónea del cantilever y pernos cortos puede originar importantes daños potenciales (aspiración, perforación de esófago, absceso y fístula enterocólica, obstrucción intestinal, terapéuticas fuertemente invasivas e incluso la misma muerte del paciente, todos sucesos con claras connotaciones legales.This clinical report describes a case of accidental swallowing of three units cantilever porcelain fused metal bridge in a 51-years-old male with history of colon cancer and reversible colostomy four years ago. While the kind of the ingested foreign body and the prior gastrointestinal conditions recommend a surgical management decision to avoid the risks for perforation or obstruction, in our case the management decision was the conservative approach because of the asymptomatic condition and the radiographic observation of the normal pass the alimentary tract without complications. The fixed dentures should be secure and stable but an incorrect design of the bridge (wrong indication of cantilever; short post systems are at increased risk of important potential harms (inhalation, oesophageal perforation, enterocolic fistula, intestinal

  15. Measurement of the Resonant Frequency of Nano-Scale Cantilevers by Hard Contact Readout

    DEFF Research Database (Denmark)

    Dohn, Søren; Hansen, Ole; Bolsen, A.

    2008-01-01

    It is shown that detection of the resonant frequency of a nano-scale cantilever is possible by measuring the time average current flowing from an electrode to the cantilever during hard contact occurring twice every cycle of the cantilever vibration. The electronic detection method is insensitive....... The readout method is thereby ideally suited for portable sensor systems....

  16. Building Bridges

    DEFF Research Database (Denmark)

    The report Building Bridges adresses the questions why, how and for whom academic audience research has public value, from the different points of view of the four working groups in the COST Action IS0906 Transforming Audiences, Transforming Societies – “New Media Genres, Media Literacy and Trust...... in the Media”, “Audience Interactivity and Participation”, “The Role of Media and ICT Use for Evolving Social Relationships” and “Audience Transformations and Social Integration”. Building Bridges is the result of an ongoing dialogue between the Action and non-academic stakeholders in the field of audience...... Belgrade), Leo Pekkala (Finnish Centre for Media Education and Audiovisual Media/MEKU), Julie Uldam (Network on Civic Engagement and Social Innovation) and Gabriella Velics (Community Media Forum Europe)....

  17. Mathematical bridges

    CERN Document Server

    Andreescu, Titu; Tetiva, Marian

    2017-01-01

    Building bridges between classical results and contemporary nonstandard problems, Mathematical Bridges embraces important topics in analysis and algebra from a problem-solving perspective. Blending old and new techniques, tactics and strategies used in solving challenging mathematical problems, readers will discover numerous genuine mathematical gems throughout that will heighten their appreciation of the inherent beauty of mathematics. Most of the problems are original to the authors and are intertwined in a well-motivated exposition driven by representative examples. The book is structured to assist the reader in formulating and proving conjectures, as well as devising solutions to important mathematical problems by making connections between various concepts and ideas from different areas of mathematics. Instructors and educators teaching problem-solving courses or organizing mathematics clubs, as well as motivated mathematics students from high school juniors to college seniors, will find Mathematical Bri...

  18. Plastic Bridge

    Institute of Scientific and Technical Information of China (English)

    履之

    1994-01-01

    Already ubiquitous in homes and cars, plastic is now appearing inbridges. An academic-industrial consortium based at the University ofCalifornia in San Diego is launching a three-year research program aimed atdeveloping the world’s first plastic highway bridge, a 450-foot span madeentirely from glass-,carbon,and polymer-fiber-reinforced composite mate-rials, the stuff of military aircraft. It will cross Interstate 5 to connect thetwo sides of the school’s campus.

  19. AFM cantilever with in situ renewable mercury microelectrode

    NARCIS (Netherlands)

    Schön, Peter; Geerlings, Joël; Tas, Niels; Sarajlic, Edin

    2013-01-01

    We report here first results obtained on a novel, in situ renewable mercury microelectrode integrated into an atomic force microscopy (AFM) cantilever. Our approach is based on a fountain pen probe with appropriate dimensions enabling reversible filling with(nonwetting) mercury under changing the ap

  20. Strategy Guideline: Quality Management in Existing Homes - Cantilever Floor Example

    Energy Technology Data Exchange (ETDEWEB)

    Taggart, J. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Sikora, J. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Wiehagen, J. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Wood, A. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States)

    2011-12-01

    This guideline is designed to highlight the QA process that can be applied to any residential building retrofit activity. The cantilevered floor retrofit detailed in this guideline is included only to provide an actual retrofit example to better illustrate the QA activities being presented.

  1. Development of an Electrochemical-Cantilever Hybrid Platform

    DEFF Research Database (Denmark)

    Fischer, Lee MacKenzie

    I denne afhandling er udviklingen af en nyskabende elektrokemisk-cantilever hybrid sensor platform præsenteret. Mikro cantileverer er meget følsomme over for ændringer i overflade stress, mens elektrokemiske metoder tillader kontrol og udlæsning af overflade ladning og potentiale. Det kan bruges...

  2. Optimised cantilever biosensor with piezoresistive read-out

    DEFF Research Database (Denmark)

    Rasmussen, Peter; Thaysen, J.; Hansen, Ole

    2003-01-01

    We present a cantilever-based biochemical sensor with piezoresistive read-out which has been optimised for measuring surface stress. The resistors and the electrical wiring on the chip are encapsulated in low-pressure chemical vapor deposition (LPCVD) silicon nitride, so that the chip is well sui...

  3. A MEMS Multi-Cantilever Variable Capacitor On Metamaterial

    Science.gov (United States)

    2009-03-26

    cantilever used for this thesis. Beam bending theory from Shigley [49] is used to produce analytical beam equations. This chapter also presents...split-ring resonators for nonlinear negative-index metamaterials,” Optics Express, vol. 14, pp. 9344– 9349, October 2006. 49. J. E. Shigley , C. R. Mischke

  4. A microfluidic AFM cantilever based dispensing and aspiration platform

    NARCIS (Netherlands)

    Van Oorschot, R.; Perez Garza, H.H.; Derks, R.J.S.; Staufer, U.; Ghatkesar, M.K.

    2015-01-01

    We present the development of a microfluidic AFM (atomic force microscope) cantilever-based platform to enable the local dispensing and aspiration of liquid with volumes in the pico-to-femtoliter range. The platform consists of a basic AFM measurement system, microfluidic AFM chip, fluidic interface

  5. Fabrication of resonant micro cantilevers with integrated transparent fluidic channel

    DEFF Research Database (Denmark)

    Khan, Faheem; Schmid, Silvan; Davis, Zachary James

    2011-01-01

    be visually observed through the transparent fluidic channel. The resonant frequency of the cantilever is changed by the fluid inside the channel, due to the change in mass. The shift in the resonant frequency can be translated into a density of the fluid or into the presence of macro/micro molecules...

  6. Drift study of SU8 cantilevers in liquid and gaseous environments

    DEFF Research Database (Denmark)

    Tenje, Maria; Keller, Stephan Sylvest; Dohn, Søren

    2010-01-01

    We present a study of the drift, in terms of cantilever deflections without probe/target interactions, of polymeric SU8 cantilevers. The drift is measured in PBS buffer (pH 7.4) and under vacuum (1 mbar) conditions. We see that the cantilevers display a large drift in both environments. We believe...... this is because the polymer matrix absorbs liquid in one situation whereas it is being degassed in the other. An inhomogeneous expansion/contraction of the cantilever is seen because one surface of the cantilever may still have remains of the release layer from the fabrication. To further study the effect, we...

  7. Simultaneous liquid viscosity and density determination with piezoelectric unimorph cantilevers

    Science.gov (United States)

    Shih, Wan Y.; Li, Xiaoping; Gu, Huiming; Shih, Wei-Heng; Aksay, Ilhan A.

    2001-01-01

    We have examined both experimentally and theoretically a piezoelectric unimorph cantilever as a liquid viscosity-and-density sensor. The fabricated piezoelectric unimorph consisted of a PbOṡZrO2ṡTiO2 (PZT) layer on a thin stainless-steel plate. In addition to a driving electrode, a sensing electrode was placed on top of the PZT layer, permitting the direct measurement of the resonance frequency. The cantilever was tested using water-glycerol solutions of different compositions. In all three of the tested modes, the resonance frequency decreased while the width of the resonance peak increased with increasing glycerol content. To account for the liquid effect, we consider the cantilever as a sphere of radius R oscillating in a liquid. By including the high and low frequency terms in the induced mass and the damping coefficient of the liquid, we show that for a given liquid density and viscosity the oscillating-sphere model predicts a resonance frequency and peak width that closely agree with experiment. Furthermore, the viscosity and the density of a liquid have been determined simultaneously using the experimentally measured resonance frequency and peak width as inputs to the oscillating-sphere model. The calculated liquid viscosity and density closely agreed with the known values, indicating that our cantilever-based sensor is effective in determining viscosity and density, simultaneously. We also show that scaling analysis predicts an increase in the width of the resonance peak with decreasing cantilever size, an observation in agreement with the large peak widths observed for microcantilevers.

  8. Internal Force Calculation of Long Cantilever Traffic Deck Slab%长悬臂行车道板的内力计算

    Institute of Scientific and Technical Information of China (English)

    孙立刚

    2012-01-01

    采用沙柯公式、贝达巴赫公式和Ansys计算分析公路桥梁长悬臂行车道板的内力,总结了计算方法,对设计工作具有一定的参考价值。%Internal force of long cantilever traffic deck slab of highway bridge is calculated and analyzed by the adoption of Sawko formula,Baider Bahkt formula,and Ansys.Calculation methods are summarized which have certain reference value for design effort.

  9. Self-assembly and sensing-group graft of pre-modified CNTs on resonant micro-cantilevers for specific detection of volatile organic compound vapors

    Science.gov (United States)

    Xu, Pengcheng; Li, Xinxin; Yu, Haitao; Liu, Min; Li, Jungang

    2010-11-01

    This paper reports MWCNT (multi-wall carbon nano-tube)-modified resonant micro-cantilever chemical sensors for detection of trinitrotoluene (TNT) vapor. The MWCNTs are pre-modified and then area-selectively self-assembled at the free-end gold pad of a micro-cantilever, in which a resonance-exciting heater and a signal-readout piezoresistive Wheatstone bridge are integrated. Featuring a high specific surface area, the MWCNTs are further functionalized with TNT-sensitive groups by grafting onto the sidewalls of the MWCNTs. To lower the non-specific absorption of water and other small organic molecules, the SiO2 surface of the micro-cantilever was also pre-treated for hydrophobicity and oleophobicity by self-assembling a monolayer of heptadecafluorodecyltrimethoxysilane. The results of our sensing experiments have shown a capability to rapidly detect ppb-level TNT vapor, and a high specificity of the functionalized groups to TNT molecules. The experiment has also confirmed a good long-term stability in detecting sensitivity.

  10. Aluminum nano-cantilevers for high sensitivity mass sensors

    DEFF Research Database (Denmark)

    Davis, Zachary James; Boisen, Anja

    2005-01-01

    We have fabricated Al nano-cantilevers using a very simple one mask contact UV lithography technique with lateral dimensions under 500 nm and vertical dimensions of approximately 100 nm. These devices are demonstrated as highly sensitive mass sensors by measuring their dynamic properties. Further......We have fabricated Al nano-cantilevers using a very simple one mask contact UV lithography technique with lateral dimensions under 500 nm and vertical dimensions of approximately 100 nm. These devices are demonstrated as highly sensitive mass sensors by measuring their dynamic properties....... Furthermore, it is shown that Al has a potential higher sensitivity than Si based dynamic sensors. Initial testing of these devices has been conducted using a novel scanning electron microscope setup were the devices were tested under high vacuum conditions. The Q-factor was measured to approximately 200...

  11. Vibrating cantilever beam in a flowing soap film

    Science.gov (United States)

    Sajjanapu, Veera; Ward, Thomas

    2016-11-01

    We present an experimental study of the interaction between a flexible cantilever beam and a flowing fluid medium using a soap film. The vertically falling soap film is capable of attaining speeds ranging from 1.5 - 3 m/s with an operating test section width of 7.5 cm. Experiments were conducted for flexible cantilever beams of length L wake with a high-speed camera. Assuming small vibrational amplitudes, we consider the Euler-Bernoulli beam theory to understand the dynamics. From the analysis we find that the normalized average displacement is linear with respect to the square of the free-stream velocity. The vibrational amplitude is also discussed using a similar scaling. Finally, visualization of the downstream vortex structure is related to a beams displacement and vibrational frequency using dimensional analysis.

  12. Vibrations of cantilevered shallow cylindrical shells of rectangular planform

    Science.gov (United States)

    Leissa, A. W.; Lee, J. K.; Wang, A. J.

    1981-01-01

    A cantilevered, shallow shell of circular cylindrical curvature and rectangular planform exhibits free vibration behavior which differs considerably from that of a cantilevered beam or of a flat plate. Some numerical results can be found for the problem in the previously published literature, mainly obtained by using various finite element methods. The present paper is the first definitive study of the problem, presenting accurate non-dimensional frequency parameters for wide ranges of aspect ratio, shallowness ratio and thickness ratio. The analysis is based upon shallow shell theory. Numerical results are obtained by using the Ritz method, with algebraic polynomial trial functions for the displacements. Convergence is investigated, with attention being given both to the number of terms taken for each co-ordinate direction and for each of the three components of displacement. Accuracy of the results is also established by comparison with finite element results for shallow shells and with other accurate flat plate solutions.

  13. Electret-based cantilever energy harvester: design and optimization

    CERN Document Server

    Boisseau, S; Sylvestre, A

    2011-01-01

    We report in this paper the design, the optimization and the fabrication of an electret-based cantilever energy harvester. We develop the mechanical and the electrostatic equations of such a device and its implementation using Finite Elements (FEM) and Matlab in order to get an accurate model. This model is then used in an optimization process. A macroscopic prototype (3.2cm^{2}) was built with a silicon cantilever and a Teflon\\textregistered electret. Thanks to this prototype, we manage to harvest 17\\muW with ambient-type vibrations of 0.2g on a load of 210M{\\Omega}. The experimental results are consistent with simulation results.

  14. Vibrations of cantilevered shallow cylindrical shells of rectangular planform

    Science.gov (United States)

    Leissa, A. W.; Lee, J. K.; Wang, A. J.

    1981-10-01

    A cantilevered, shallow shell of circular cylindrical curvature and rectangular planform exhibits free vibration behavior which differs considerably from that of a cantilevered beam or of a flat plate. Some numerical results can be found for the problem in the previously published literature, mainly obtained by using various finite element methods. The present paper is the first definitive study of the problem, presenting accurate non-dimensional frequency parameters for wide ranges of aspect ratio, shallowness ratio and thickness ratio. The analysis is based upon shallow shell theory. Numerical results are obtained by using the Ritz method, with algebraic polynomial trial functions for the displacements. Convergence is investigated, with attention being given both to the number of terms taken for each co-ordinate direction and for each of the three components of displacement. Accuracy of the results is also established by comparison with finite element results for shallow shells and with other accurate flat plate solutions.

  15. Stability Analysis of Long-Span Continuous Rigid Frame Bridge with Thin-Wall Pier

    Institute of Scientific and Technical Information of China (English)

    HE Bo; SHI Ya-nan; ZHU Hong-ping; GUO Wen-zeng; CHEN Yong

    2008-01-01

    During cantilever cast in construction of high-pier and large-span continuous rigid frame bridges, structural stability in the longest cantilevered stage is very important. Based on a practical design case of a large-span continuous rigid frame bridge in Wuhan, the longest span stability coefficient is calculated with linear-buckling and nonlinear-buckling methods, respectively. The influences of both geometrical nonlinearity and the dual nonlinearity of material and geometry are considered. Numerical results indicate that the nonlinear solution is necessary to stability analysis because linear buckling loads axe much higher than those of nonlinear buckling. Thus, the edge fiber yield criterion is more convenient and faster than ultimate loading criterion when estimating nonlinear stability of structure, and can be used easily in the initial engineering design.

  16. Vibration of a Cantilever Beam in Ambient Fluid

    CERN Document Server

    Metzger, C; Zypman, F

    2016-01-01

    Here we obtain analytical expressions for the frequency response of a cantilever beam in the presence of ambient fluid. The advantage of our approach, besides its simplicity of use, is that it explicitly contains the viscosity and the density of the ambient fluid. Thus, if measuring the frequency spectrum, the expression can be used in the design of viscometers. Conversely, if the ambient fluid is known, the expression can be used in the design of force gauges such as in Atomic Force Microscopy.

  17. Non-Linear Piezoelectric Actuator with a Preloaded Cantilever Beam

    OpenAIRE

    Yue Wu; Jingshi Dong; Xinbo Li; Zhigang Yang; Qingping Liu

    2015-01-01

    Piezoelectric actuation is widely used for the active vibration control of smart structural systems, and corresponding research has largely focused on linear electromechanical devices. This paper investigates the design and analysis of a novel piezoelectric actuator that uses a piezoelectric cantilever beam with a loading spring to produce displacement outputs. This device has a special nonlinear property relating to converting between kinetic energy and potential energy, and it can be used t...

  18. Optical fiber accelerometer based on a silicon micromachined cantilever

    Science.gov (United States)

    Malki, Abdelrafik; Lecoy, Pierre; Marty, Jeanine; Renouf, Christine; Ferdinand, Pierre

    1995-12-01

    An intensity-modulated fiber-optic accelerometer based on backreflection effects has been manufactured and tested. It uses a multimode fiber placed at a spherical mirror center, and the beam intensity is modulated by a micromachined silicon cantilever. This device has applications as an accelerometer and vibrometer for rotating machines. It exhibits an amplitude linearity of +/-1.2% in the range of 0.1-22 m s-2, a frequency linearity of +/-1% in the

  19. Accurate Method for Determining Adhesion of Cantilever Beams

    Energy Technology Data Exchange (ETDEWEB)

    Michalske, T.A.; de Boer, M.P.

    1999-01-08

    Using surface micromachined samples, we demonstrate the accurate measurement of cantilever beam adhesion by using test structures which are adhered over long attachment lengths. We show that this configuration has a deep energy well, such that a fracture equilibrium is easily reached. When compared to the commonly used method of determining the shortest attached beam, the present method is much less sensitive to variations in surface topography or to details of capillary drying.

  20. Solution and Positive Solution to Nonlinear Cantilever Beam Equations

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Using the decomposition technique of equation and the fixed point theorem, the existence of solution and positive solution is studied for a nonlinear cantilever beam equation. The equation describes the deformation of the elastic beam with a fixed end and a free end. The main results show that the equation has at least one solution or positive solution, provided that the "height" of nonlinear term is appropriate on a bounded set.

  1. Modeling and optimal design of multilayer thermal cantilever microactuators

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A model of curvature and tip deflection of multilayer thermal cantilever actuators is derived.The sim-plified expression received from the model avoids inverting complex matrices enhances understanding and makes it easier to optimize the structure parameters.Experiment is performed,the modeled and experimental results demonstrate the validity of the model,and it also indicates that Young’s module makes great contribution to the deflection;therefore,thin layers cannot be ignored arbitrarily.

  2. An Astigmatic Detection System for Polymeric Cantilever-based Sensors

    DEFF Research Database (Denmark)

    Hwu, En-Te; Liao, Hsien-Shun; Bosco, Filippo;

    2012-01-01

    We demonstrate the use of an astigmatic detection system (ADS) for resonance frequency identification of polymer microcantilever sensors. The ADS technology is based on a DVD optical head combined with an optical microscope (OM). The optical head has a signal bandwidth of 80 MHz, allowing thermal...... submicrometer-sized cantilevers. The resonant frequency of SU-8 microcantilevers is measured by both thermal fluctuation and excited vibration measurement modes of the ADS....

  3. STATIC STUDY OF CANTILEVER BEAM STICTION UNDER ELECTROSTATIC FORCE INFLUENCE

    Institute of Scientific and Technical Information of China (English)

    ZhangYin; ZhaoYa-pu

    2004-01-01

    The model and analysis of the cantilever beam adhesion problem under the action of electrostatic force are given. Owing to the nonlinearity of electrostatic force, the analytical solution for this kind of problem is not available. In this paper, a systematic method of generating polynomials which are the exact beam solutions of the loads with different distributions is provided. The polynomials are used to approximate the beam displacement due to electrostatic force. The equilibrium equation offers an answer to how the beam deforms but no information about the unstuck length. The derivative of the functional with respect to the unstuck length offers such information. But to compute the functional it is necessary to know the beam deformation, So the problem is iteratively solved until the results are converged. Galerkin and Newton-Raphson methods are used to solve this nonlinear problem. The effects of dielectric layer thickness and electrostatic voltage on the cantilever beam stiction are studied. The method provided in this paper exhibits good convergence. For the adhesion problem of cantilever beam without electrostatic voltage, the analytical solution is available and is also exactly matched by the computational results given by the method presented in this paper.

  4. Vibration analysis of magnetostrictive thin-film composite cantilever actuator

    Science.gov (United States)

    Xu, Yan; Shang, Xinchun

    2016-09-01

    The transverse vibration of a composed cantilever beam with magnetostrictive layer is analyzed, which is employed to simulate dynamic response of an actuator. The high-order shear deformation theory of beam and the coupling magnetoelastic constitutive relationship are introduced to construct the governing equations, all interface conditions between magnetostrictive film and elastic substrate as well as the free stress condition on the top and bottom surfaces of the beam can be satisfied. In order to demonstrate validity of the presented mathematical modeling, the verification examples are also given. Furthermore, the effect of geometry and material parameters on dynamic characteristics of magnetostrictive cantilever beam, such as the nature frequency and amplitude, is discussed. Moreover, through computing the magneto-mechanical coupling factor of the beam structure, the variation tendency curves of the factor along with different parameters and frequencies of magnetostrictive cantilever beam actuator have been presented. These numerical results should be useful for the design of beam-type with magnetostrictive thin-film actuators.

  5. Investigations on antibody binding to a micro-cantilever coated with a BAM pesticide residue

    DEFF Research Database (Denmark)

    Bache, Michael; Taboryski, Rafael Jozef; Schmid, Silvan;

    2011-01-01

    The attachment of an antibody to an antigen-coated cantilever has been investigated by repeated experiments, using a cantilever-based detection system by Cantion A/S. The stress induced by the binding of a pesticide residue BAM (2,6 dichlorobenzamide) immobilized on a cantilever surface to anti......-BAM antibody is measured using the CantiLab4© system from Cantion A/S with four gold-coated cantilevers and piezo resistive readout. The detection mechanism is in principle label-free, but fluorescent-marked antibodies have been used to subsequently verify the binding on the cantilever surface. The bending...... and increase in mass of each cantilever has also been investigated using a light interferometer and a Doppler Vibrometer. The system has been analyzed during repeated measurements to investigate whether the CantiLab4© system is a suited platform for a pesticide assay system. © 2011 Bache et al....

  6. Automated cantilever exchange and optical alignment for High-throughput, parallel atomic force microscopy

    CERN Document Server

    Bijnagte, Tom; Kramer, Lukas; Dekker, Bert; Herfst, Rodolf; Sadeghian, Hamed

    2016-01-01

    In atomic force microscopy (AFM), the exchange and alignment of the AFM cantilever with respect to the optical beam and position-sensitive detector (PSD) are often performed manually. This process is tedious and time-consuming and sometimes damages the cantilever or tip. To increase the throughput of AFM in industrial applications, the ability to automatically exchange and align the cantilever in a very short time with sufficient accuracy is required. In this paper, we present the development of an automated cantilever exchange and optical alignment instrument. We present an experimental proof of principle by exchanging various types of AFM cantilevers in 6 seconds with an accuracy better than 2 um. The exchange and alignment unit is miniaturized to allow for integration in a parallel AFM. The reliability of the demonstrator has also been evaluated. Ten thousand continuous exchange and alignment cycles were performed without failure. The automated exchange and alignment of the AFM cantilever overcome a large ...

  7. Investigations on antibody binding to a micro-cantilever coated with a BAM pesticide residue

    Directory of Open Access Journals (Sweden)

    Aamand Jens

    2011-01-01

    Full Text Available Abstract The attachment of an antibody to an antigen-coated cantilever has been investigated by repeated experiments, using a cantilever-based detection system by Cantion A/S. The stress induced by the binding of a pesticide residue BAM (2,6 dichlorobenzamide immobilized on a cantilever surface to anti-BAM antibody is measured using the CantiLab4© system from Cantion A/S with four gold-coated cantilevers and piezo resistive readout. The detection mechanism is in principle label-free, but fluorescent-marked antibodies have been used to subsequently verify the binding on the cantilever surface. The bending and increase in mass of each cantilever has also been investigated using a light interferometer and a Doppler Vibrometer. The system has been analyzed during repeated measurements to investigate whether the CantiLab4© system is a suited platform for a pesticide assay system.

  8. Cable Supported Bridges

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    Cable supported bridges in the form of suspension bridges and cable-stayed bridges are distinguished by their ability to overcome large spans.The book concentrates on the synthesis of cable supported bridges, covering both design and construction aspects. The analytical part covers simple methods...

  9. Self-aligned cantilever positioning for on-substrate measurements using DVD pickup head

    DEFF Research Database (Denmark)

    Bosco, Filippo; Hwu, E. T.; Keller, Stephan Urs

    2010-01-01

    In this paper, we present a novel approach for measuring the resonant frequency of cantilevers fabricated in polymeric materials. We re-designed the use of a commercial DVD-ROM pickup head and combine it with a glass-polymer substrate in order to obtain a light and portable device to measure...... the resonant frequency of polymer cantilevers. The use of the Pyrex-SU-8 clamping substrate allows an easy replacement of the cantilever chips and a fast alignment process to the DVD-ROM laser beam. We show measurements of thermal noise for SU-8 and TOPAS cantilevers in air and liquid environment....

  10. Multi-directional energy harvesting by piezoelectric cantilever-pendulum with internal resonance

    Energy Technology Data Exchange (ETDEWEB)

    Xu, J.; Tang, J., E-mail: jtang@engr.uconn.edu [Department of Mechanical Engineering, The University of Connecticut, Storrs, Connecticut 06269 (United States)

    2015-11-23

    This letter reports a piezoelectric cantilever-pendulum design for multi-directional energy harvesting. A pendulum is attached to the tip of a piezoelectric cantilever-type energy harvester. This design aims at taking advantage of the nonlinear coupling between the pendulum motion in 3-dimensional space and the beam bending vibration at resonances. Experimental studies indicate that, under properly chosen parameters, 1:2 internal resonance can be induced, which enables the multi-directional energy harvesting with a single cantilever. The advantages of the design with respect to traditional piezoelectric cantilever are examined.

  11. Integrated optical readout for miniaturization of cantilever-based sensor system

    DEFF Research Database (Denmark)

    Nordström, Maria; Zauner, Dan; Calleja, Montserrat;

    2007-01-01

    The authors present the fabrication and characterization of an integrated optical readout scheme based on single-mode waveguides for cantilever-based sensors. The cantilever bending is read out by monitoring changes in the optical intensity of light transmitted through the cantilever that also acts...... as a waveguide. The complete system is fabricated in the photosensitive polymer SU-8. They show theoretical calculations on the expected sensitivity both when operated in air and liquid and compare these with experimental characterization of the system in air where the cantilever is deflected mechanically....... The experimental results compare well with the results obtained from the theoretical calculations....

  12. Bridges in Complex Networks

    CERN Document Server

    Wu, Ang-Kun; Liu, Yang-Yu

    2016-01-01

    A bridge in a graph is an edge whose removal disconnects the graph and increases the number of connected components. We calculate the fraction of bridges in a wide range of real-world networks and their randomized counterparts. We find that real networks typically have more bridges than their completely randomized counterparts, but very similar fraction of bridges as their degree-preserving randomizations. We define a new edge centrality measure, called bridgeness, to differentiate the importance of a bridge in damaging a network. We find that certain real networks have very large average and variance of bridgeness compared to their degree-preserving randomizations and other real networks. Finally, we offer an analytical framework to calculate the bridge fraction and average bridgeness for uncorrelated random networks with arbitrary degree distributions.

  13. Nonlinear Dynamics of Cantilever-Sample Interactions in Atomic Force Microscopy

    Science.gov (United States)

    Cantrell, John H.; Cantrell, Sean A.

    2010-01-01

    The interaction of the cantilever tip of an atomic force microscope (AFM) with the sample surface is obtained by treating the cantilever and sample as independent systems coupled by a nonlinear force acting between the cantilever tip and a volume element of the sample surface. The volume element is subjected to a restoring force from the remainder of the sample that provides dynamical equilibrium for the combined systems. The model accounts for the positions on the cantilever of the cantilever tip, laser probe, and excitation force (if any) via a basis set of set of orthogonal functions that may be generalized to account for arbitrary cantilever shapes. The basis set is extended to include nonlinear cantilever modes. The model leads to a pair of coupled nonlinear differential equations that are solved analytically using a matrix iteration procedure. The effects of oscillatory excitation forces applied either to the cantilever or to the sample surface (or to both) are obtained from the solution set and applied to the to the assessment of phase and amplitude signals generated by various acoustic-atomic force microscope (A-AFM) modalities. The influence of bistable cantilever modes of on AFM signal generation is discussed. The effects on the cantilever-sample surface dynamics of subsurface features embedded in the sample that are perturbed by surface-generated oscillatory excitation forces and carried to the cantilever via wave propagation are accounted by the Bolef-Miller propagating wave model. Expressions pertaining to signal generation and image contrast in A-AFM are obtained and applied to amplitude modulation (intermittent contact) atomic force microscopy and resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM). The influence of phase accumulation in A-AFM on image contrast is discussed, as is the effect of hard contact and maximum nonlinearity regimes of A-AFM operation.

  14. Assistant pullback technique for main span closure of Sutong Bridge

    Institute of Scientific and Technical Information of China (English)

    Chen Ming; Luo Chengbin; Wu Qihe; Zhang Yongtao; You Xinpeng

    2009-01-01

    Sutong Bridge is a cable-stayed steel box girder bridge with a main span of 1 088 m. The erection of upper structure adopts geometry control method and requires no change to the unit's size and the structure's none-stress geometry. Before main span closure, the cantilever of girder reaches 540.8 m, the structure state is noticeably influenced by external circumstances, the main span closure face great difficulty. By abstracting the advantage of the pullback method abroad and the domestic temperature-cutting method, a new assistant pullback method have put forward and bring into practice actually. In this paper, the analysis key point of practice conditions, key parameter of practice, main measures of the method and the performance is introduced.

  15. Piezoelectric Bimorph Cantilever for Vibration-Producing-Hydrogen

    Directory of Open Access Journals (Sweden)

    Guangming Cheng

    2012-12-01

    Full Text Available A device composed of a piezoelectric bimorph cantilever and a water electrolysis device was fabricated to realize piezoelectrochemical hydrogen production. The obvious output of the hydrogen and oxygen through application of a mechanical vibration of ~0.07 N and ~46.2 Hz was observed. This method provides a cost-effective, recyclable, environment-friendly and simple way to directly split water for hydrogen fuels by scavenging mechanical waste energy forms such as noise or traffic vibration in the environment.

  16. Alternative Actuation and Detection Principles for Resonating Cantilevers

    DEFF Research Database (Denmark)

    Grigorov, Alexander

    2006-01-01

    Mikro-elektro mekaniske systemer (MEMS) er ny en teknologi med stort potentiale for kommerciel anvendelse indenfor såvel generel og biokemisk som biomolekylær detektion. Cantilever sensorer er et eksisterende MEMS koncept, der kan bruges til detektion af enten statisk overfladestress fremkaldt af...... strukturer og processer blev derefter brugt til integration på system niveau og mulig funktionalisering af enheder til statiske og dynamiske målinger, der bruger solide og afbrudte kanaler, ”spotting”, og kapilær handlinger til at få diverse væsker til at flyde....

  17. Design of cantilever probes for Atomic Force Microscopy (AFM)

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2000-01-01

    A cantilever beam used in an Atomic Force Microscope is optimized with respect to two different objectives. The first goal is to maximize the first eigenfrequency while keeping the stiffness of the probe constant. The second goal is to maximize the tip angle of the first eigenmode while again...... keeping the stiffness constant. The resulting design of the beam from the latter optimization gives almost the same result as when maximizing the first eigenfrequency. Adding a restriction on the second eigenfrequency result in a significant change of the optimal design. The beam is modelled with 12 DOF...

  18. Bending analysis of a functionally graded piezoelectric cantilever beam

    Institute of Scientific and Technical Information of China (English)

    YU Tao; ZHONG Zheng

    2007-01-01

    A new analysis based on Airy stress function method is presented for a functionally graded piezoelectric material cantilever beam.Assuming that the mechanical and electric properties of the material have the same variations along the thickness direction,a two-dimensional plane elasticity solution is obtained for the coupling electroelastic fields of the beam under different loadings.This solution will be useful in analyzing FGPM beam with arbitrary variations of material properties.The influences of the functionally graded material properties on the structural response of the beam subjected to different loads are also studied through numerical examples.

  19. Bending analysis of a functionally graded piezoelectric cantilever beam

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new analysis based on Airy stress function method is presented for a functionally graded piezoelectric material cantilever beam. Assuming that the mechanical and electric properties of the material have the same variations along the thickness direction, a two-dimensional plane elasticity solution is obtained for the coupling electroelastic fields of the beam under different loadings. This solution will be useful in analyzing FGPM beam with arbitrary variations of material properties. The influences of the functionally graded material properties on the structural response of the beam subjected to different loads are also studied through numerical examples.

  20. Automatic Optical Crack Tracking for Double Cantilever Beam Specimens

    Science.gov (United States)

    2015-01-01

    and Member, R.G., ‘‘Path Planning For Machine Vision Assisted , Teleoperated Pavement Crack Sealer,’’ Journal of Transportation Engineering 124:137...TECHN ICAL ART IC LE Automatic Optical Crack Tracking for Double Cantilever Beam Specimens B. Krull1,2, J. Patrick2,3, K. Hart2,4, S. White2,4, and N...Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 3 Department of Civil and Environmental Engineering, University of

  1. Temperature enhanced photothermal cooling of a micro-cantilever

    CERN Document Server

    Fu, Hao; Mao, Tian-hua; Cao, Gengyu

    2014-01-01

    We present a temperature enhanced photothermal cooling scheme in a micro-cantilever based FP cavity. Experiments at various temperatures show a temperature dependence of photothermal cooling efficiency. And approximate one order of improvement on the cooling efficiency is achieved experimentally when the temperature decreases from 298 K to 100 K. Numerical analysis reveals that the dramatic change of the cooling efficiency is attributed to the temperature dependent dynamics of the photothermal backaction. A high efficient cooling can be achieved by controlling the temperature for an optimized the dynamics of photothermal backaction.

  2. Micro-cantilever flow sensor for small aircraft

    KAUST Repository

    Ghommem, Mehdi

    2013-10-01

    We extend the use of cantilever beams as flow sensors for small aircraft. As such, we propose a novel method to measure the airspeed and the angle of attack at which the air travels across a small flying vehicle. We measure beam deflections and extract information about the surrounding flow. Thus, we couple a nonlinear beam model with a potential flow simulator through a fluid-structure interaction scheme. We use this numerical approach to generate calibration curves that exhibit the trend for the variations of the limit cycle oscillations amplitudes of flexural and torsional vibrations with the air speed and the angle of attack, respectively. © The Author(s) 2013.

  3. Heater-Integrated Cantilevers for Nano-Samples Thermogravimetric Analysis

    Directory of Open Access Journals (Sweden)

    Valeria Toffoli

    2013-12-01

    Full Text Available The design and characteristics of a micro-system for thermogravimetric analysis (TGA in which heater, temperature sensor and mass sensor are integrated into a single device are presented. The system consists of a suspended cantilever that incorporates a microfabricated resistor, used as both heater and thermometer. A three-dimensional finite element analysis was used to define the structure parameters. TGA sensors were fabricated by standard microlithographic techniques and tested using milli-Q water and polyurethane microcapsule. The results demonstrated that our approach provides a faster and more sensitive TGA with respect to commercial systems.

  4. Analytical simulation of the cantilever-type energy harvester

    Directory of Open Access Journals (Sweden)

    Jie Mei

    2016-01-01

    Full Text Available This article describes an analytical model of the cantilever-type energy harvester based on Euler–Bernoulli’s beam theory. Starting from the Hamiltonian form of total energy equation, the bending mode shapes and electromechanical dynamic equations are derived. By solving the constitutive electromechanical dynamic equation, the frequency transfer function of output voltage and power can be obtained. Through a case study of a unimorph piezoelectric energy harvester, this analytical modeling method has been validated by the finite element method.

  5. A DVD-ROM based high-throughput cantilever sensing platform

    DEFF Research Database (Denmark)

    Bosco, Filippo

    and mechanics from a DVD player to handle liquid samples and to read-out cantilever deflection and resonant frequency. In a few minutes, several liquid samples can be analyzed in parallel, measuring over several hundreds of individual cantilevers. Three generations of systems have been developed and tested...

  6. Encased cantilevers for low-noise force and mass sensing in liquids

    NARCIS (Netherlands)

    Ziegler, D.; Klaassen, A.; Bahri, D.; Chmielewski, D.; Nievergelt, A.; Mugele, F.; Sader, J.; Ashby, P.D.

    2014-01-01

    Viscous damping severely limits the performance of resonator based sensing in liquids. We present encased cantilevers that overcome this limitation with a transparent and hydrophobic encasement built around the resonator. Only a few micrometers of the cantilever probe protrude from the encasement an

  7. Tuning a racetrack ring resonator by an integrated dielectric MEMS cantilever

    NARCIS (Netherlands)

    Abdulla, S.M.C.; Kauppinen, L.J.; Dijkstra, M.; Boer, de M.J.; Berenschot, E.; Jansen, H.V.; Ridder, de R.M.; Krijnen, G.J.M.

    2011-01-01

    The principle, fabrication and characterization of a dielectric MEMS cantilever located a few 100 nm above a racetrack ring resonator are presented. After fabrication of the resonators on silicon-on-insulator (SOI) wafers in a foundry process, the cantilevers were integrated by surface micromachinin

  8. Cantilever-based bio-chemical sensor integrated in a microliquid handling system

    DEFF Research Database (Denmark)

    Thaysen, Jacob; Marie, Rodolphe; Boisen, Anja

    2001-01-01

    The cantilevers have integrated piezoresistive readout which, compared to optical readout, enables simple measurements on even non-transparent liquids, such as blood. First, we introduce a simple theory for using piezoresistive cantilevers as surface stress sensors. Then, the sensor fabrication b...

  9. Switching through intermediate states seen in a single nickel nanorod by cantilever magnetometry.

    Science.gov (United States)

    Lee, Sanggap; Moore, Eric W; Hickman, Steven A; Longenecker, Jonilyn G; Marohn, John A

    2012-04-15

    In-plane to out-of-plane magnetization switching in a single nickel nanorod affixed to an attonewton-sensitivity cantilever was studied at cryogenic temperatures. We observe multiple sharp, simultaneous transitions in cantilever frequency, dissipation, and frequency jitter associated with magnetic switching through distinct intermediate states. These findings suggest a new route for detecting magnetic fields at the nanoscale.

  10. Sustainability Assessment of Precast Ultra-High Performance Fiber Reinforced Concrete (UHPFRC Cantilever Retaining Walls

    Directory of Open Access Journals (Sweden)

    Behzad Nematollahi

    2014-05-01

    Full Text Available This study evaluates the environmental impacts of a newly designed precast Ultra-High Performance Fiber Reinforced Concrete (UHPFRC cantilever retaining wall as a sustainable alternative approach compared with the conventional precast Reinforced Concrete (RC cantilever retaining wall. Nowadays, according to the shocking reports of many researchers worldwide global warming is one of the most devastating problems of human being. To date, lots of research has been undertaken in the concrete industry to tackle this issue through reducing the environmental footprints of our structural designs. In this regard, UHPFRC technology offers substantial benefits through efficient use of materials as well as optimization of the structural designs resulting less CO2 emissions, Embodied Energy (EE and Global Warming Potential (GWP. UHPFRC as a sustainable construction material is mostly appropriate for the use in the fabrication of precast members such as precast concrete cantilever retaining walls. This study demonstrates the overview of the designed precast concrete cantilever retaining wall manufactured from UHPFRC and its Environmental Impact Calculations (EIC versus the conventional precast RC cantilever retaining walls. Based on the EIC results, the precast UHPFRC cantilever retaining walls are generally more environmentally sustainable than those built of the conventional RC with respect to the reduction of CO2 emissions, EE and GWP. In summary, the precast UHPFRC cantilever retaining wall proposed in this study is an alternative sustainable solution compared with the conventional precast RC cantilever retaining wall which can be used in many civil engineering projects.

  11. A novel fabrication technique for free-hanging homogeneous polymeric cantilever waveguides

    DEFF Research Database (Denmark)

    Nordström, M.; Calleja, M.; Hübner, Jörg;

    2008-01-01

    We present a novel bonding technique developed for the fabrication of a cantilever-based biosensing system with integrated optical read-out. The read-out mechanism is based on single-mode waveguides fabricated monolithically in SU-8. For optimal operation of the read-out mode, the cantilever wave...

  12. Cantilever-based sensor with integrated optical read-out using single mode waveguides

    DEFF Research Database (Denmark)

    Nordström, Maria; Zauner, Dan; Calleja, Montserrat;

    2007-01-01

    This work presents the design, fabrication and mechanical characterisation of an integrated optical read-out scheme for cantilever-based biosensors. A cantilever can be used as a biosensor by monitoring its bending caused by the surface stress generated due to chemical reactions occurring on its ...

  13. Study on the Spatial Stress of the Chongqing Yangtze River Bridge in China

    Directory of Open Access Journals (Sweden)

    Yan Li

    2014-09-01

    Full Text Available Continuous rigid-frame bridges are usually used in building bridges with long span and high piers. It is characterized by the consolidation between piers and beams in the middle of bridge piers and flexible bridge piers in the lower part. Among all the factors, curvature has the most obvious influence on the stress of curved continuous rigid-frame bridge, because of which, the curved beam bridge produces coupling effect of bending moment and receives complicated stress, leading to the deformation such as torsion and displacement of radial direction. No matter it is the castscaffold construction or cantilever construction, for continuous rigid-frame bridges, considering that after the long term creep of concrete, structure stress tends to be in a drop-frame state, so it is necessary to know the mechanical properties of the finished bridge. Taking the Chongqing Yangtze River Bridge as an example, this paper mainly analyzes the internal forces and deformations of a finished curved continuotus rigid-frame bridge by establishing a spatial finite element model with Midas Civil 2006 software and by changing the model’s radius of curvature. The results show that as the curvature increases, the vertical deformation and torsion angle of the long-span curved continuous rigid-frame bridge are both reduced under the effect of a dead load and prestressed load, presenting mechanical properties of bridge, namely, “coupling effect of bending moment”. In the model analyzed, the deformation of the bridge in the transverse direction also behaves a trend of gradual decrease with an increase in radius of curvature with the range 500–2000 m.

  14. Controlling the opto-mechanics of a cantilever in an interferometer via cavity loss

    Science.gov (United States)

    von Schmidsfeld, A.; Reichling, M.

    2015-09-01

    In a non-contact atomic force microscope, based on interferometric cantilever displacement detection, the optical return loss of the system is tunable via the distance between the fiber end and the cantilever. We utilize this for tuning the interferometer from a predominant Michelson to a predominant Fabry-Pérot characteristics and introduce the Fabry-Pérot enhancement factor as a quantitative measure for multibeam interference in the cavity. This experimentally easily accessible and adjustable parameter provides a control of the opto-mechanical interaction between the cavity light field and the cantilever. The quantitative assessment of the light pressure acting on the cantilever oscillating in the cavity via the frequency shift allows an in-situ measurement of the cantilever stiffness with remarkable precision.

  15. Controlling the opto-mechanics of a cantilever in an interferometer via cavity loss

    Energy Technology Data Exchange (ETDEWEB)

    Schmidsfeld, A. von, E-mail: avonschm@uos.de; Reichling, M., E-mail: reichling@uos.de [Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, 49076 Osnabrück (Germany)

    2015-09-21

    In a non-contact atomic force microscope, based on interferometric cantilever displacement detection, the optical return loss of the system is tunable via the distance between the fiber end and the cantilever. We utilize this for tuning the interferometer from a predominant Michelson to a predominant Fabry-Pérot characteristics and introduce the Fabry-Pérot enhancement factor as a quantitative measure for multibeam interference in the cavity. This experimentally easily accessible and adjustable parameter provides a control of the opto-mechanical interaction between the cavity light field and the cantilever. The quantitative assessment of the light pressure acting on the cantilever oscillating in the cavity via the frequency shift allows an in-situ measurement of the cantilever stiffness with remarkable precision.

  16. APPROXIMATE SOLUTIONS FOR TRANSIENT RESPONSE OF CONSTRAINED DAMPING LAMINATED CANTILEVER PLATE

    Institute of Scientific and Technical Information of China (English)

    Liuwei Mao; Anwen Wang; Mingyong Hu

    2010-01-01

    The series composed by beam mode function is used to approximate the displacement function of constrained damping of laminated cantilever plates,and the transverse deformation of the plate on which a concentrated force is acted is calculated using the principle of virtual work.By solving Lagrange's equation,the frequencies and model loss factors of free vibration of the plate are obtained,then the transient response of constrained damping of laminated cantilever plate is obtained,when the concentrated force is withdrawn suddenly.The theoretical calculations are compared with the experimental data,the results show:both the frequencies and the response time of theoretical calculation and its variational law with the parameters of the damping layer are identical with experimental results.Also,the response time of steel cantilever plate,unconstrained damping cantilever plate and constrained damping cantilever plate are brought into comparison,which shows that the constrained damping structure can effectively suppress the vibration.

  17. Polymeric Micro-channel-based Functionalisation System for Micro-Cantilevers

    DEFF Research Database (Denmark)

    Nordström, Maria; Gomez, Montserrat; Boisen, Anja

    2005-01-01

    A micro-channel system intended for functionalising micro-cantilevers used for biochemical detection has been designed, realised and characterised. The chip is fabricated in the resist SU-8, which is a photosensitive polymer offering a fast, cost-efficient and easy processing. Cantilevers present...... a new platform for biochemical detection with a high sensitivity. This micro-channel system is used for treating such a cantilever array with probe molecules prior to detection and it can also be used as the analysis set-up. The design of the micro-channel system provides a simple way of coating...... separate sections of a cantilever array with different probe molecules. The use of this channel system eliminates the time-consuming step of addressing each cantilever individually to obtain an array functionalised with different probe molecules. Using this micro-channel system in combination...

  18. Tuning a racetrack ring resonator by an integrated dielectric MEMS cantilever.

    Science.gov (United States)

    Abdulla, S M C; Kauppinen, L J; Dijkstra, M; de Boer, M J; Berenschot, E; Jansen, H V; de Ridder, R M; Krijnen, G J M

    2011-08-15

    The principle, fabrication and characterization of a dielectric MEMS cantilever located a few 100 nm above a racetrack ring resonator are presented. After fabrication of the resonators on silicon-on-insulator (SOI) wafers in a foundry process, the cantilevers were integrated by surface micromachining techniques. Off-state deflections of the cantilevers have been optimized to appropriately position them near the evanescent field of the resonator. Using electrostatic actuation, moving the cantilevers into this evanescent field, the propagation properties of the ring waveguide are modulated. We demonstrate 122 pm tuning of the resonance wavelength of the optical ring resonator (in the optical C-band) without change of the optical quality factor, on application of 9 V to a 40 µm long cantilever. This compact integrated device can be used for tuning/switching a specific wavelength, with very little energy for operation and negligible cross talk with surrounding devices.

  19. Mechanical behavior simulation of MEMS-based cantilever beam using COMSOL multiphysics

    Energy Technology Data Exchange (ETDEWEB)

    Acheli, A., E-mail: aacheli@cdta.dz; Serhane, R. [Centre de Développement des Technologies Avancées (CDTA). BP n°17 Baba Hassen, Alger (Algeria)

    2015-03-30

    This paper presents the studies of mechanical behavior of MEMS cantilever beam made of poly-silicon material, using the coupling of three application modes (plane strain, electrostatics and the moving mesh) of COMSOL Multi-physics software. The cantilevers playing a key role in Micro Electro-Mechanical Systems (MEMS) devices (switches, resonators, etc) working under potential shock. This is why they require actuation under predetermined conditions, such as electrostatic force or inertial force. In this paper, we present mechanical behavior of a cantilever actuated by an electrostatic force. In addition to the simplification of calculations, the weight of the cantilever was not taken into account. Different parameters like beam displacement, electrostatics force and stress over the beam have been calculated by finite element method after having defining the geometry, the material of the cantilever model (fixed at one of ends but is free to move otherwise) and his operational space.

  20. Vibration energy harvester with sustainable power based on a single-crystal piezoelectric cantilever array.

    Science.gov (United States)

    Kim, Moonkeun; Lee, Sang-Kyun; Ham, Yong-Hyun; Yang, Yil Suk; Kwon, Jong-Kee; Kwon, Kwang-Ho

    2012-08-01

    We designed and fabricated a bimorph cantilever array for sustainable power with an integrated Cu proof mass to obtain additional power and current. We fabricated a cantilever system using single-crystal piezoelectric material and compared the calculations for single and arrayed cantilevers to those obtained experimentally. The vibration energy harvester had resonant frequencies of 60.4 and 63.2 Hz for short and open circuits, respectively. The damping ratio and quality factor of the cantilever device were 0.012 and 41.66, respectively. The resonant frequency at maximum average power was 60.8 Hz. The current and highest average power of the harvester array were found to be 0.728 mA and 1.61 mW, respectively. The sustainable maximum power was obtained after slightly shifting the short-circuit frequency. In order to improve the current and power using an array of cantilevers, we also performed energy conversion experiments.

  1. Effect of tip mass on frequency response and sensitivity of AFM cantilever in liquid.

    Science.gov (United States)

    Farokh Payam, Amir; Fathipour, Morteza

    2015-03-01

    The effect of tip mass on the frequency response and sensitivity of atomic force microscope (AFM) cantilever in the liquid environment is investigated. For this purpose, using Euler-Bernoulli beam theory and considering tip mass and hydrodynamic functions in a liquid environment, an expression for the resonance frequencies of AFM cantilever in liquid is derived. Then, based on this expression, the effect of the surface contact stiffness on the flexural mode of a rectangular AFM cantilever in fluid is investigated and compared with the case where the AFM cantilever operates in the air. The results show that in contrast with an air environment, the tip mass has no significant impact on the resonance frequency and sensitivity of the AFM cantilever in the liquid. Hence, analysis of AFM behaviour in liquid environment by neglecting the tip mass is logical.

  2. The importance of cantilever dynamics in the interpretation of Kelvin probe force microscopy.

    Science.gov (United States)

    Satzinger, Kevin J; Brown, Keith A; Westervelt, Robert M

    2012-09-15

    A realistic interpretation of the measured contact potential difference (CPD) in Kelvin probe force microscopy (KPFM) is crucial in order to extract meaningful information about the sample. Central to this interpretation is a method to include contributions from the macroscopic cantilever arm, as well as the cone and sharp tip of a KPFM probe. Here, three models of the electrostatic interaction between a KPFM probe and a sample are tested through an electrostatic simulation and compared with experiment. In contrast with previous studies that treat the KPFM cantilever as a rigid object, we allow the cantilever to bend and rotate; accounting for cantilever bending provides the closest agreement between theory and experiment. We demonstrate that cantilever dynamics play a major role in CPD measurements and provide a simulation technique to explore this phenomenon.

  3. Study of node and mass sensitivity of resonant mode based cantilevers with concentrated mass loading

    Science.gov (United States)

    Zhang, Kewei; Chai, Yuesheng; Fu, Jiahui

    2015-12-01

    Resonant-mode based cantilevers are an important type of acoustic wave based mass-sensing devices. In this work, the governing vibration equation of a bi-layer resonant-mode based cantilever attached with concentrated mass is established by using a modal analysis method. The effects of resonance modes and mass loading conditions on nodes and mass sensitivity of the cantilever were theoretically studied. The results suggested that the node did not shift when concentrated mass was loaded on a specific position. Mass sensitivity of the cantilever was linearly proportional to the square of the point displacement at the mass loading position for all the resonance modes. For the first resonance mode, when mass loading position xc satisfied 0 xc xc ≤ l. Mass sensitivity did not change when concentrated mass was loaded at the rigid end. This work can provide scientific guidance to optimize the mass sensitivity of a resonant-mode based cantilever.

  4. Modelling of a cantilever non-symmetric piezoelectric bimorph

    Science.gov (United States)

    Brissaud, Michel; Ledren, Sarah; Gonnard, P.

    2003-11-01

    The aim of this paper is the modelling of a non-symmetric bimorph constituted by a piezoelectric material deposited on an alumina substrate and used either as an actuator or a sensor. Theoretical modelling based on the flexural modes of the structure is carried out and the influence of the electrode characteristics (geometrical dimensions and elastic parameters) is introduced in the modelling for calculating the bimorph bending displacement. In actuator mode, the electrical admittance of the cantilever non-symmetric bimorph is stated and the intrinsic electromechanical coupling factor linked to the bimorph bending motion is deduced and compared with that defined in IEEE Standards. The analytical modelling was used for characterizing a cantilever bimorph constituted by a piezoelectric thick film deposited on an alumina substrate. A trial and error fitting method is described for determining the elastic, piezoelectric and dielectric constants of the piezoelectric material. The influence of the electrode parameters is calculated and the measurement uncertainty is deduced. In sensor mode the open voltage delivered by the bent piezoelectric layer and the electrical equivalent circuit of the bimorph are given. Theoretical results are compared with those obtained by the finite element method, and discussed.

  5. Optimising Performance of a Cantilever-type Micro Accelerometer Sensor

    Directory of Open Access Journals (Sweden)

    B.P. Joshi

    2007-05-01

    Full Text Available A technique for optimising performance of cantilever-type micro acceleration sensor hasbeen developed. Performance of a sensor is judged mainly by its sensitivity and bandwidth.Maximising product of these two important parameters of inertial sensors helps to optimise thesensor performance. It is observed that placement of a lumped mass (add-mass on the sensor'sproof-mass helps to control both sensitivity and the first resonant frequency of the cantileverstructure to the designer's choice. Simulation and modelling of various dimensions of rectangularstructures for acceleration sensor with this novel add-mass technique are discussed. CoventorwareMEMSCAD has been used to model, simulate, and carry out FEM analysis. A simple analyticalmodel is discussed to elaborate the mechanics of cantilever-type micro accelerometer. Thecomparison of the results obtained from analytical model and the finite element simulations revealthese to be in good agreement. The advantages of this technique for choosing the two mostimportant sensor parameters (i.e., sensitivity and bandwidth of an inertial sensor are brought out.

  6. Higher Order Modes Excitation of Micro Cantilever Beams

    KAUST Repository

    Jaber, Nizar

    2014-05-01

    In this study, we present analytical and experimental investigation of electrically actuated micro cantilever based resonators. These devices are fabricated using polyimide and coated with chrome and gold layers from both sides. The cantilevers are highly curled up due to stress gradient, which is a common imperfection in surface micro machining. Using a laser Doppler vibrometer, we applied a noise signal to experimentally find the first four resonance frequencies. Then, using a data acquisition card, we swept the excitation frequency around the first four natural modes of vibrations. Theoretically, we derived a reduced order model using the Galerkin method to simulate the dynamics of the system. Extensive numerical analysis and computations were performed. The numerical analysis was able to provide good matching with experimental values of the resonance frequencies. Also, we proved the ability to excite higher order modes using partial electrodes with shapes that resemble the shape of the mode of interest. Such micro-resonators are shown to be promising for applications in mass and gas sensing.

  7. Taizhou Yangtze River Bridge

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Taizhou Bridge lies between Taizhou, Zhenjiang and Changzhou City in Jiangsu Province. The total length of Taizhou Bridge is 62.088 kin. The whole line is designed by freeway codes with six lanes in two directions. The wholeinvestment is 9.37 billion RMB and the planned construction duration is 5.5 years. The main bridge crossing the Yangtze River is a continuous three-pylon two-span suspension bridge with the main span of 1 080 m. The bridge system is realized for the first time and ranks first in the world until now.

  8. Nondestructive testing and hardness measurement based on contact resonance of piezoelectric cantilevers (Conference Presentation)

    Science.gov (United States)

    Li, Faxin; Fu, Ji

    2016-04-01

    A suitable defect identification parameter is very important in the field of nondestructive testing (NDT). In this work, we proposed a NDT method which detects the sample's local contact stiffness (LCS) based on the contact resonance of a piezoelectric cantilever. Firstly, through finite element analysis we showed that LCS is quite sensitive to typical defects including debonding, voids, cracks and inclusions, making it a good identification parameter. Secondly, a homemade NDT system containing a piezoelectric unimorph cantilever was assembled to detect the sample's LCS by tracking the contact resonance frequency (CRF) of the cantilever-sample system based on strain signals. Testing results indicated that this NDT system could detect the above mentioned defects efficiently. The cantilever-stiffness dependent detection sensitivity was specially investigated and the stiffer cantilevers were found to be more sensitive to small defects. Then, a piezoelectric bimorph cantilever was fabricated and the electromechanical impedance, other than the strain signals, was measured to track the CRF of the cantilever-system. The LCS is then derived by using the equivalent-circuit model. The electromechanical impedance based NDT system is more compact and can be further developed to be a portable device. Finally, a Vicker indenter is fabricated onto the bimorph tip and the contact area is derived from the measured LCS. Thus the NDT system turns to be a hardness tester without any optical devices. It is very useful for in-situ testing or testing on inner surfaces where conventional hardness tester is not applicable.

  9. Imaging via complete cantilever dynamic detection: general dynamic mode imaging and spectroscopy in scanning probe microscopy

    Science.gov (United States)

    Somnath, Suhas; Collins, Liam; Matheson, Michael A.; Sukumar, Sreenivas R.; Kalinin, Sergei V.; Jesse, Stephen

    2016-10-01

    We develop and implement a multifrequency spectroscopy and spectroscopic imaging mode, referred to as general dynamic mode (GDM), that captures the complete spatially- and stimulus dependent information on nonlinear cantilever dynamics in scanning probe microscopy (SPM). GDM acquires the cantilever response including harmonics and mode mixing products across the entire broadband cantilever spectrum as a function of excitation frequency. GDM spectra substitute the classical measurements in SPM, e.g. amplitude and phase in lock-in detection. Here, GDM is used to investigate the response of a purely capacitively driven cantilever. We use information theory techniques to mine the data and verify the findings with governing equations and classical lock-in based approaches. We explore the dependence of the cantilever dynamics on the tip–sample distance, AC and DC driving bias. This approach can be applied to investigate the dynamic behavior of other systems within and beyond dynamic SPM. GDM is expected to be useful for separating the contribution of different physical phenomena in the cantilever response and understanding the role of cantilever dynamics in dynamic AFM techniques.

  10. Fast nanotopography imaging using a high speed cantilever with integrated heater-thermometer.

    Science.gov (United States)

    Lee, Byeonghee; Somnath, Suhas; King, William P

    2013-04-05

    This paper presents a high speed tapping cantilever with an integrated heater-thermometer for fast nanotopography imaging. The cantilever is much smaller and faster than previous heated cantilevers, with a length of 35 μm and a resonant frequency of 1.4 MHz. The mechanical response time is characterized by scanning over a backward-facing step of height 20 nm. The mechanical response time is 77 μs in air and 448 μs in water, which compares favorably to the fastest commercial cantilevers that do not have integrated heaters. The doped silicon cantilever is designed with an integrated heater that can heat and cool in about 10 μs and can operate in both air and water. We demonstrate standard laser-based topography imaging along with thermal topography imaging, when the cantilever is actuated via the piezoelectric shaker in an atomic force microscope system and when it is actuated by Lorentz forces. The cantilever can perform thermal topography imaging in tapping mode with an imaging resolution of 7 nm at a scan speed of 1.46 mm s(-1).

  11. Investigation of Subcombination Internal Resonances in Cantilever Beams

    Directory of Open Access Journals (Sweden)

    Haider N. Arafat

    1998-01-01

    Full Text Available Activation of subcombination internal resonances in transversely excited cantilever beams is investigated. The effect of geometric and inertia nonlinearities, which are cubic in the governing equation of motion, is considered. The method of time-averaged Lagrangian and virtual work is used to determine six nonlinear ordinary-differential equations governing the amplitudes and phases of the three interacting modes. Frequency- and force-response curves are generated for the case ω ≈ ω4 ≈ 1/2(ω2 + ω5. There are two possible responses: single-mode and three-mode responses. The single-mode periodic response is found to undergo supercritical and subcritical pitchfork bifurcations, which result in three-mode interactions. In the case of three-mode responses, there are conditions where the low-frequency mode dominates the response, resulting in high-amplitude quasiperiodic oscillations.

  12. Probing Mechanical Resonances in Cantilevered Coiled Carbon Nanowires

    Science.gov (United States)

    Saini, Deepika; Dickel, Doyl; Behlow, Herbert; Pillai, Balu; Yang, Keqin; Skove, Malcolm; Serkiz, Steven; Rao, Apparao; Clemson University Team; Savannah River National Laboratory Team

    2013-03-01

    Helically coiled carbon nanowires (CCNW) and nanotubes are promising elements for use in MEMS/NEMS devices and nanorobotics, as nano-inductors and sensors, and for impact protection (e.g. Bell et al. 2007 IEEE International Conference, J. Appl. Phys. 100, 064309 (2006)). Understanding and characterizing their mechanical resonance behavior is essential for the reliability in applications. In this study, we have electrically actuated an individual CCNW in a diving-board cantilever configuration inside a scanning electron microscope, and electrically detected its mechanical resonance modes. By oscillation at low frequency we confirmed the induced-charge actuation mechanism. Among the modes we observed, some appeared to have both axial and lateral components. We also observed closely spaced resonance modes which we attribute to the splitting of degenerate modes, consistent with our COMSOL simulations. We suggest that the helical morphology facilitates inter-mode coupling that results in the observed complex resonance behavior.

  13. Nonlinear dynamics of nanoelectromechanical cantilevers based on nanowire piezoresistive detection

    Directory of Open Access Journals (Sweden)

    Baguet S.

    2012-07-01

    Full Text Available The nonlinear dynamics of in-plane nanoelectromechanical cantilevers based on silicon nanowire piezoresistive detection is investigated using a comprehensive analytical model that remains valid up to large displacements in the case of electrostatic actuation. This multiphysics model takes into account geometric, inertial and electrostatic nonlinearities as well as the fringing field effects which are significant for thin resonators. The bistability as well as multistability limits are considered in order to provide close-form expressions of the critical amplitudes. Third order nonlinearity cancellation is analytically inspected and set via an optimal DC drive voltage which permits the actuation of the NEMS beyond its critical amplitude. It may result on a large enhancement of the sensor performances by driving optimally the nanocantilever at very large amplitude, while suppressing the hysteresis.

  14. Atomic resolution in noncontact AFM by probing cantilever frequency shifts

    Institute of Scientific and Technical Information of China (English)

    Hong Yong Xie

    2007-01-01

    Rutile TiO2(001) quantum dots (or nano-marks) in different shapes were used to imitate uncleaved material surfaces or materials with rough surfaces. By numerical integration of the equation of motion of cantilever for silicon tip scanning along the [110] direction over the rutile TiO2 (001) quantum dots in ultra high vacuum (UHV), scanning routes were explored to achieve atomic resolution from frequency shift image. The tip-surface interaction forces were calculated from Lennard-Jones (12-6) potential by the Hamaker summation method. The calculated results showed that atomic resolution could be achieved by frequency shift image for TiO2 (001) surfaces of rhombohedral quantum dot scanning in a vertical route, and spherical cap quantum dot scanning in a superposition route.

  15. Asymptotic analysis of a vibrating cantilever with a nonlinear boundary

    Institute of Scientific and Technical Information of China (English)

    CHEN LiQun; C.W.LIM; HU QingQuan; DING Hu

    2009-01-01

    Nonlinear vibration of a cantilever in a contact atomic force microscope is analyzed via an asymptotic approach.The asymptotic solution is sought for a beam equation with a nonlinear boundary condition.The steady-state responses are determined in primary resonance and subharmonic resonance.The relations between the response amplitudes and the excitation frequencies and amplitudes are derived from the solvability condition.Multivaluedness occurs in the relations as a consequence of the nonlinearity.The stability of steady-state responses is analyzed by use of the Lyapunov linearized sta-bility theory.The stability analysis predicts the jumping phenomenon for certain parameters.The curves of the response amplitudes changing with the excitation frequencies are numerically compared with those obtained via the method of multiple scales.The calculation results demonstrate that the two methods predict the same varying tendencies while there are small quantitative differences.

  16. Asymptotic analysis of a vibrating cantilever with a nonlinear boundary

    Science.gov (United States)

    Chen, Liqun; Lim, C. W.; Hu, Qingquan; Ding, Hu

    2009-09-01

    Nonlinear vibration of a cantilever in a contact atomic force microscope is analyzed via an asymptotic approach. The asymptotic solution is sought for a beam equation with a nonlinear boundary condition. The steady-state responses are determined in primary resonance and subharmonic resonance. The relations between the response amplitudes and the excitation frequencies and amplitudes are derived from the solvability condition. Multivaluedness occurs in the relations as a consequence of the nonlinearity. The stability of steady-state responses is analyzed by use of the Lyapunov linearized stability theory. The stability analysis predicts the jumping phenomenon for certain parameters. The curves of the response amplitudes changing with the excitation frequencies are numerically compared with those obtained via the method of multiple scales. The calculation results demonstrate that the two methods predict the same varying tendencies while there are small quantitative differences.

  17. High-performance micromachined gyroscope with a slanted suspension cantilever

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Dingbang; Wu Xuezhong; Hou Zhanqiang; Chen Zhihua; Dong Peitao; Li Shengyi, E-mail: Dingbangxiao@yahoo.com.c [Microsystem Laboratory, National University of Defense Technology, Changsha 410073 (China)

    2009-04-15

    This paper presents a novel structure for improving the stability and the mechanical noise of micromachined gyroscopes. Only one slanted cantilever is used for suspension in this gyroscope, so the asymmetry spring and the thermal stress, which most micromachined gyroscopes suffer from, are reduced. In order to reduce the mechanical noise, the proof masses are designed to be much larger than in most micromachined gyroscopes. The gyroscope chip is sealed at 0.001 Pa vacuum. A gyroscope sample and its read-out circuit are fabricated. The scale factor of this gyroscope is measured as 57.6 mV/(deg/sec) with a nonlinearity better than 0.12% in a measurement range of +-100 deg/sec. The short-term bias stability in 20 min is 60 deg/h.

  18. High-performance micromachined gyroscope with a slanted suspension cantilever

    Institute of Scientific and Technical Information of China (English)

    Xiao Dingbang; Wu Xuezhong; Hou Zhanqiang; Chen Zhihua; Dong Peitao; Li Shengyi

    2009-01-01

    This paper presents a novel structure for improving the stability and the mechanical noise of micromachined gyroscopes.Only one slanted cantilever is used for suspension in this gyroscope,so the asymmetry spring and the thermal stress,which most micromachined gyroscopes suffer from,are reduced.In order to reduce the mechanical noise,the proof masses are designed to be much larger than in most micromachined gyroscopes.The gyroscope chip is sealed at 0.00 1 Pa vacuum.A gyroscope sample and its read-out circuit are fabricated.The scale factor of this gyroscope is measured as 57.6 mV/(deg/sec) with a nonlinearity better than 0.12%in a measurement range of ±100 deg/sec.The short-term bias stability in 20 min is 60 deg/h.

  19. Strategy Guideline: Quality Management in Existing Homes; Cantilever Floor Example

    Energy Technology Data Exchange (ETDEWEB)

    Taggart, J.; Sikora, J.; Wiehagen, J.; Wood, A.

    2011-12-01

    This guideline is designed to highlight the QA process that can be applied to any residential building retrofit activity. The cantilevered floor retrofit detailed in this guideline is included only to provide an actual retrofit example to better illustrate the QA activities being presented. The goal of existing home high performing remodeling quality management systems (HPR-QMS) is to establish practices and processes that can be used throughout any remodeling project. The research presented in this document provides a comparison of a selected retrofit activity as typically done versus that same retrofit activity approached from an integrated high performance remodeling and quality management perspective. It highlights some key quality management tools and approaches that can be adopted incrementally by a high performance remodeler for this or any high performance retrofit. This example is intended as a template and establishes a methodology that can be used to develop a portfolio of high performance remodeling strategies.

  20. Interdisciplinary cantilever physics: Elasticity of carrot, celery, and plasticware

    Science.gov (United States)

    Pestka, Kenneth A.

    2014-05-01

    This article presents several simple cantilever-based experiments using common household items (celery, carrot, and a plastic spoon) that are appropriate for introductory undergraduate laboratories or independent student projects. By applying Hooke's law and Euler beam theory, students are able to determine Young's modulus, fracture stress, yield stress, strain energy, and sound speed of these apparently disparate materials. In addition, a cellular foam elastic model is introduced—applicable to biologic materials as well as an essential component in the development of advanced engineering composites—that provides a mechanism to determine Young's modulus of the cell wall material found in celery and carrot. These experiments are designed to promote exploration of the similarities and differences between common inorganic and organic materials, fill a void in the typical undergraduate curriculum, and provide a foundation for more advanced material science pursuits within biology, botany, and food science as well as physics and engineering.

  1. Asymptotic analysis of a vibrating cantilever with a nonlinear boundary

    Institute of Scientific and Technical Information of China (English)

    C.; W.; LIM

    2009-01-01

    Nonlinear vibration of a cantilever in a contact atomic force microscope is analyzed via an asymptotic approach. The asymptotic solution is sought for a beam equation with a nonlinear boundary condition. The steady-state responses are determined in primary resonance and subharmonic resonance. The relations between the response amplitudes and the excitation frequencies and amplitudes are derived from the solvability condition. Multivaluedness occurs in the relations as a consequence of the nonlinearity. The stability of steady-state responses is analyzed by use of the Lyapunov linearized stability theory. The stability analysis predicts the jumping phenomenon for certain parameters. The curves of the response amplitudes changing with the excitation frequencies are numerically compared with those obtained via the method of multiple scales. The calculation results demonstrate that the two methods predict the same varying tendencies while there are small quantitative differences.

  2. Modeling and experimental vibration analysis of nanomechanical cantilever active probes

    Science.gov (United States)

    Salehi-Khojin, Amin; Bashash, Saeid; Jalili, Nader

    2008-08-01

    Nanomechanical cantilever (NMC) active probes have recently received increased attention in a variety of nanoscale sensing and measurement applications. Current modeling practices call for a uniform cantilever beam without considering the intentional jump discontinuities associated with the piezoelectric layer attachment and the NMC cross-sectional step. This paper presents a comprehensive modeling framework for modal characterization and dynamic response analysis of NMC active probes with geometrical discontinuities. The entire length of the NMC is divided into three segments of uniform beams followed by applying appropriate continuity conditions. The characteristics matrix equation is then used to solve for system natural frequencies and mode shapes. Using an equivalent electromechanical moment of a piezoelectric layer, forced motion analysis of the system is carried out. An experimental setup consisting of a commercial NMC active probe from Veeco and a state-of-the-art microsystem analyzer, the MSA-400 from Polytec, is developed to verify the theoretical developments proposed here. Using a parameter estimation technique based on minimizing the modeling error, optimal values of system parameters are identified. Mode shapes and the modal frequency response of the system for the first three modes determined from the proposed model are compared with those obtained from the experiment and commonly used theory for uniform beams. Results indicate that the uniform beam model fails to accurately predict the actual system response, especially in multiple-mode operation, while the proposed discontinuous beam model demonstrates good agreement with the experimental data. Such detailed and accurate modeling framework can lead to significant enhancement in the sensitivity of piezoelectric-based NMC sensors for use in variety of sensing and imaging applications.

  3. Fabrication and characterization of SRN/SU-8 bimorph cantilevers for temperature sensing

    DEFF Research Database (Denmark)

    Larsen, Tom; Keller, Stephan Sylvest; Schmid, Silvan

    2011-01-01

    Polymer coated ceramic cantilevers are highly sensitive to temperature changes, due to the large difference in coefficient of thermal expansion of the two materials. Silicon rich nitride (SRN) cantilevers coated with SU-8 for temperature sensing were fabricated and tested. The devices were coated......) shrinkage of SU-8 with increasing temperature, due to evaporation of absorbed moisture and (ii) thermal expansion of SRN and SU-8. Separately, these two effects generate bending in opposite direction. The observed overall bending was seen to be a combination of both. In nitrogen atmosphere, the cantilevers...

  4. Enhancing thermally induced effects on atomic force microscope cantilevers using optical microcavities

    Science.gov (United States)

    Duy Vy, Nguyen; Iida, Takuya

    2016-12-01

    A theory of enhancing thermally induced effects on atomic force microscope cantilevers with respect to the input power is proposed. An optical microcavity is used to increase the absorbed power and radiation pressure on thin films. We show that the response to the input power is enhanced up to an order of magnitude for cantilevers of ∼200 µm in length and ∼0.5 µm in thickness. A decrease in the absorbed power in the presence of cantilever deflection increases system endurability with respect to the input power. The study gives methods for amplifying and tuning vibration amplitudes in amplitude modulation modes with high sensitivity and low controlling input power.

  5. Atomic force microscopy: Loading position dependence of cantilever spring constants and detector sensitivity

    Science.gov (United States)

    Vakarelski, Ivan U.; Edwards, Scott A.; Dagastine, Raymond R.; Chan, Derek Y. C.; Stevens, Geoffrey W.; Grieser, Franz

    2007-11-01

    A simple and accurate experimental method is described for determining the effective cantilever spring constant and the detector sensitivity of atomic force microscopy cantilevers on which a colloidal particle is attached. By attaching large (approximately 85μm diameter) latex particles at various positions along the V-shaped cantilevers, we demonstrate how the normal and lateral spring constants as well as the sensitivity vary with loading position. Comparison with an explicit point-load theoretical model has also been used to verify the accuracy of the method.

  6. Integrated MOSFET-Embedded-Cantilever-Based Biosensor Characteristic for Detection of Anthrax Simulant

    Energy Technology Data Exchange (ETDEWEB)

    Mostafa, Salwa [University of Tennessee, Knoxville (UTK); Lee, Ida [ORNL; Islam, Syed K [University of Tennessee, Knoxville (UTK); Eliza, Sazia A. [University of Tennessee, Knoxville (UTK); Shekhawat, Gajendra [Northwestern University, Evanston; Dravid, Vinayak [Northwestern University, Evanston; Tulip, Fahmida S [ORNL

    2011-01-01

    In this work, MOSFET-embedded cantilevers are configured as microbial sensors for detection of anthrax simulants, Bacillus thuringiensis. Anthrax simulants attached to the chemically treated gold-coated cantilever cause changes in the MOSFET drain current due to the bending of the cantilever which indicates the detection of anthrax simulant. Electrical properties of the anthrax simulant are also responsible for the change in the drain current. The test results suggest a detection range of 10 L of stimulant test solution (a suspension population of 1.3 107 colony-forming units/mL diluted in 40% ethanol and 60% deionized water) with a linear response of 31 A/ L.

  7. A Compact, Low-Power Cantilever-Based Sensor Array for Chemical Detection

    Energy Technology Data Exchange (ETDEWEB)

    Loui, A; Ratto, T; Wilson, T; Mukerjee, E; Hu, Z; Sulchek, T; Hart, B

    2007-02-22

    A compact and low-power cantilever-based sensor array has been developed and used to detect various vapor analytes. This device employs sorptive polymers that are deposited onto piezoresistive cantilevers. We have successfully detected several organic vapors, representing a breadth of chemical properties and over a range of concentrations. Comparisons of the polymer/vapor partition coefficient to the cantilever deflection responses show that a simple linear relationship does not exist, emphasizing the need to develop an appropriate functional model to describe the chemical-to-mechanical transduction that is unique to this sensing modality.

  8. Spatial spectrograms of vibrating atomic force microscopy cantilevers coupled to sample surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Ryan; Raman, Arvind, E-mail: raman@purdue.edu [Birck Nanotechnology Center, 1205 W. State Street, Purdue University, West Lafayette, Indiana 47907 (United States); Proksch, Roger, E-mail: Roger.Proksch@oxinst.com [Asylum Research, 6310 Hollister Ave., Santa Barbara, California 93117 (United States)

    2013-12-23

    Many advanced dynamic Atomic Force Microscopy (AFM) techniques such as contact resonance, force modulation, piezoresponse force microscopy, electrochemical strain microscopy, and AFM infrared spectroscopy exploit the dynamic response of a cantilever in contact with a sample to extract local material properties. Achieving quantitative results in these techniques usually requires the assumption of a certain shape of cantilever vibration. We present a technique that allows in-situ measurements of the vibrational shape of AFM cantilevers coupled to surfaces. This technique opens up unique approaches to nanoscale material property mapping, which are not possible with single point measurements alone.

  9. Super-resolution optical microscopy based on scannable cantilever-combined microsphere.

    Science.gov (United States)

    Wang, Shuying; Zhang, Dongxian; Zhang, Haijun; Han, Xu; Xu, Rui

    2015-12-01

    We report an ingenious method of super-resolution optical microscopy utilizing scannable cantilever-combined microsphere. By scanning the microsphere over the sample surface in a cantilever-combined microsphere-sample contact state, super-resolution images can be acquired at arbitrary sample regions through near-field information collection by the microsphere. In addition, such a state can effectively reduce the possibility of breaking the cantilever and damaging the microsphere or sample surface. This work has developed a new method and technique of sub-diffraction-limit optical microscopy, and can be practically applied in various fields of micro/nanoscopy.

  10. Novel printing process for the fabrication of cantilever structures by the partially controlled sintering of ink

    Science.gov (United States)

    Kanazawa, Shusuke; Kusaka, Yasuyuki; Yamamoto, Noritaka; Ushijima, Hirobumi

    2017-01-01

    We present a novel process for manufacturing cantilever structures by the additive stacking of ink layers. The three-dimensional transfer of printed mechanical parts was achieved by optimizing the ink-sintering conditions to guarantee the structural integrity of the printed parts and provide adequate differences in adhesion strengths between the receiver and donor interfaces. A metal–insulator–metal cantilever structure with a bottom electrode, air insulator, and cantilevered top electrode was fabricated on a flexible film, forming a successful capacitive bending sensor for use on human bodies. This process allows highly efficient device fabrication in the MEMS field.

  11. Fast optical cooling of a nanomechanical cantilever by a dynamical Stark-shift gate

    CERN Document Server

    Yan, Leilei; Zhang, Shuo; Feng, Mang

    2014-01-01

    The efficient cooling of the nanomechanical resonators is essential to exploration of quantum properties of the macroscopic or mesoscopic systems. We propose such a laser-cooling scheme for a nanomechanical cantilever, which works even for the low-frequency mechanical mode and under weak cooling lasers. The cantilever is attached by a diamond nitrogen-vacancy center under a strong magnetic field gradient and the cooling is assisted by a dynamical Stark-shift gate. Our scheme can effectively enhance the desired cooling efficiency by avoiding the off-resonant and unexpected carrier transitions, and thereby cool the cantilever down to the vicinity of the vibrational ground state in a fast fashion.

  12. Fast optical cooling of a nanomechanical cantilever by a dynamical Stark-shift gate

    Science.gov (United States)

    Yan, Leilei; Zhang, Jian-Qi; Zhang, Shuo; Feng, Mang

    2015-10-01

    The efficient cooling of nanomechanical resonators is essential to exploration of quantum properties of the macroscopic or mesoscopic systems. We propose such a laser-cooling scheme for a nanomechanical cantilever, which works even for the low-frequency mechanical mode and under weak cooling lasers. The cantilever is coupled by a diamond nitrogen-vacancy center under a strong magnetic field gradient and the cooling is assisted by a dynamical Stark-shift gate. Our scheme can effectively enhance the desired cooling efficiency by avoiding the off-resonant and undesired carrier transitions, and thereby cool the cantilever down to the vicinity of the vibrational ground state in a fast fashion.

  13. Air-spaced PDMS piezo-electret cantilevers for vibration energy harvesting

    Science.gov (United States)

    Kachroudi, A.; Basrour, S.; Rufer, L.; Jomni, F.

    2016-11-01

    This paper reports a design of a new prototype of air-spaced cantilevers made from a micro-structured PDMS piezo-electret material for accelerometer and energy harvesting applications. The test performed on these cantilevers in a sensor mode exhibits a stable sensitivity of 385 mV/g for a frequency ranging from 5 Hz to 200 Hz that encompass most macro-scale vibrations. In the energy harvesting mode, the cantilever generates a power of 103 nW with a load resistance of 217 MΩ.

  14. Sustainable Bridge Infrastructure Procurement

    DEFF Research Database (Denmark)

    Safi, Mohammed; Du, Guangli; Simonsson, Peter

    2016-01-01

    The lack of a flexible but systematic approach for integrating lifecycle aspects into bridge investment decisions is a major obstacle hindering the procurement of sustainable bridge infrastructures. This paper addresses this obstacle by introducing a holistic approach that agencies could use...... to procure the most “sustainable” (lifecycle-efficient) bridge through a fair design-build (D-B) tendering process, considering all the main aspects: life-cycle cost (LCC), service life-span, aesthetic demands and environmental impacts (LCA)....

  15. Bridge Crossing Simulator

    Science.gov (United States)

    2014-10-07

    Requirement BCS Computer-controlled hydraulic actuation system to impart simulated crossing loads on an entire bridge structure undergoing fatigue test ...structure. Bridge test site with prepared embankments corresponding to the span and bank condition requirements of the bridge under test Conduct real...Center (AEC). (5) Sample size and number of crossings required. The number of required simulated crossings to conduct fatigue testing per the

  16. Bridging the Gap

    OpenAIRE

    Kramer Overgaard, Majken; Broeng, Jes; Jensen, Monika Luniewska; Murdock, Karen; Schmidt, Iben Julie

    2015-01-01

    Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures. Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ve...

  17. Bridging the Gap

    DEFF Research Database (Denmark)

    Kramer Overgaard, Majken; Broeng, Jes; Jensen, Monika Luniewska;

    Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures.......Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures....

  18. Semiconductor bridge (SCB) detonator

    Science.gov (United States)

    Bickes, Jr., Robert W.; Grubelich, Mark C.

    1999-01-01

    The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge igniter that comprises a pair of electrically conductive lands connected by a semiconductor bridge. The semiconductor bridge is in operational or direct contact with the explosive material, whereby current flowing through the semiconductor bridge causes initiation of the explosive material. Header wires connected to the electrically-conductive lands and electrical feed-throughs of the header posts of explosive devices, are substantially coaxial to the direction of current flow through the SCB, i.e., substantially coaxial to the SCB length.

  19. Exact Solution of Quantum Dynamics of a Cantilever Coupling to a Single Trapped Ultracold Ion

    Institute of Scientific and Technical Information of China (English)

    LIU Tao; FENG Mang; WANG Ke-Lin

    2007-01-01

    The quantum behavior of a precooled cantilever can be probed highly efficiently by electrostatically coupling to a trapped ultracold ion, in which a fast cooling of the cantilever down to the ground vibrational state is possible.Within a simple model with an ultracold ion coupled to a cantilever with only few vibrational quanta, we solve the dynamics of the coupling system by a squeezed-state expansion technique, and can in principle obtain the exact solution of the time-evolution of the coupling system in the absence of the rotating-wave approximation. Comparing to the treatment under the rotating-wave approximation, we present a more accurate description of the quantum behavior of the cantilever.

  20. Electrothermally driven high-frequency piezoresistive SiC cantilevers for dynamic atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Boubekri, R.; Cambril, E.; Couraud, L.; Bernardi, L.; Madouri, A. [LPN, CNRS-UPR20, route de Nozay, 91460 Marcoussis (France); Portail, M. [Centre de Recherche sur l' Hetero-Epitaxie et ses Applications CNRS, Rue Bernard Gregory, 06560 Valhonne (France); Chassagne, T.; Moisson, C.; Zielinski, M. [NOVASiC, Savoie Technolac, Arche bât 4, BP 267, 73375 Le Bourget du Lac Cedex (France); Jiao, S.; Michaud, J.-F.; Alquier, D. [Université François Rabelais, Tours, GREMAN, CNRS-UMR7347, 16 rue Pierre et Marie Curie, BP 7155, 37071 Tours Cedex 2 (France); Bouloc, J.; Nony, L.; Bocquet, F.; Loppacher, C. [IM2NP-CNRS/Aix-Marseille University, 38 rue Frédéric Joliot-Curie, 13451 Marseille (France); Martrou, D.; Gauthier, S., E-mail: gauthier@cemes.fr [CEMES, CNRS UPR 8011 et Université de Toulouse, 29 rue Jeanne Marvig, 31055 Toulouse (France)

    2014-08-07

    Cantilevers with resonance frequency ranging from 1 MHz to 100 MHz have been developed for dynamic atomic force microscopy. These sensors are fabricated from 3C-SiC epilayers grown on Si(100) substrates by low pressure chemical vapor deposition. They use an on-chip method both for driving and sensing the displacement of the cantilever. A first gold metallic loop deposited on top of the cantilever is used to drive its oscillation by electrothermal actuation. The sensing of this oscillation is performed by monitoring the resistance of a second Au loop. This metallic piezoresistive detection method has distinct advantages relative to more common semiconductor-based schemes. The optimization, design, fabrication, and characteristics of these cantilevers are discussed.

  1. Nanoscale deflection detection of a cantilever-based biosensor using MOSFET structure: A theoretical analysis

    Science.gov (United States)

    Paryavi, Mohsen; Montazeri, Abbas; Tekieh, Tahereh; Sasanpour, Pezhman

    2016-10-01

    A novel method for detection of biological species based on measurement of cantilever deflection has been proposed and numerically evaluated. Employing the cantilever as a moving gate of a MOSFET structure, its deflection can be analyzed via current characterization of the MOSFET consequently. Locating the cantilever as a suspended gate of a MOSFET on a substrate, the distance between cantilever and oxide layer will change the carrier concentration. Accordingly, it will be resulted in different current voltage characteristics of the device which can be easily measured using simple apparatuses. In order to verify the proposed method, the performance of system has been theoretically analyzed using COMSOL platform. The simulation results have confirmed the performance and sensitivity of the proposed method.

  2. High Quality Factor Silicon Cantilever Driven by PZT Actuator for Resonant Based Mass Detection

    CERN Document Server

    Lu, Jian; Zhang, Yi; Mihara, Takashi; Itoh, Toshihiro; Maeda, Ryutaro

    2008-01-01

    A high quality factor (Q-factor) piezoelectric lead zirconat titanate (PZT) actuated single crystal silicon cantilever was proposed in this paper for resonant based ultra-sensitive mass detection. Energy dissipation from intrinsic mechanical loss of the PZT film was successfully compressed by separating the PZT actuator from resonant structure. Excellent Q-factor, which is several times larger than conventional PZT cantilever, was achieved under both atmospheric pressure and reduced pressures. For a 30 micrometer-wide 100 micrometer-long cantilever, Q-factor was measured as high as 1113 and 7279 under the pressure of 101.2 KPa and 35 Pa, respectively. Moreover, it was found that high-mode vibration can be realized by the cantilever for the pursuit of great Q-factor, while support loss became significant because of the increased vibration amplitude at the actuation point. An optimized structure using node-point actuation was suggested then to suppress corresponding energy dissipation.

  3. Analytic and laser vibrometry study of squeeze film damping of MEMS cantilevers

    Science.gov (United States)

    Vignola, Joseph F.; Judge, John A.; Lawrence, Eric; Jarzynski, Jacek; Houston, Brian

    2006-06-01

    This study compares theoretical predictions to experimental measurements of squeeze film damping of MEMS cantilevers in a fluid environment. A series of MEMS cantilevers were fabricated on a silicon wafer. Each of the silicon beams was 2 μm thick and 18 μm wide. The lengths range from 100 to 800 μm and the air-filled gap between the cantilever and the substrate was 6 μm. An analytic model for squeeze film damping was used to predict the corresponding quality factor Q squeeze film (the ratio of the mechanical energy stored in the oscillator to the energy dissipated per cycle) for these cantilevers. The results from the modeling are compared to experimental results obtained using a Polytec MSA-400 Micro System Analyzer.

  4. Fabrication of a cantilever-based microfluidic flow meter with nL min(-1) resolution

    DEFF Research Database (Denmark)

    Noeth, Nadine-Nicole; Keller, Stephan Sylvest; Boisen, Anja

    2011-01-01

    A microfluidic flow meter based on cantilever deflection is developed, showing a resolution down to 3 nL min(-1) for flows in the microliter range. The cantilevers are fabricated in SU-8 and have integrated holes with dimensions from 5 x 5 to20x 20 mu m(2). The holes make it possible to measure......). With this etch the cantilever structures are under-etched before they are released by tweezers and the release yield is enhanced from 41.5% to 84.0%. In a continuous flow mode, the deflection of the cantilevers is directly proportional to the flow rate. By tuning the design of the integrated grid (hole size......, hole-to-hole distance, amount of holes, etc) the sensitivity of the sensor can be changed....

  5. Actuating Mechanism and Design of a Cylindrical Traveling Wave Ultrasonic Motor Using Cantilever Type Composite Transducer

    OpenAIRE

    Yingxiang Liu; Weishan Chen; Junkao Liu; Shengjun Shi

    2010-01-01

    BACKGROUND: Ultrasonic motors (USM) are based on the concept of driving the rotor by a mechanical vibration excited on the stator via piezoelectric effect. USM exhibit merits such as simple structure, quick response, quiet operation, self-locking when power off, nonelectromagnetic radiation and higher position accuracy. PRINCIPAL FINDINGS: A cylindrical type traveling wave ultrasonic motor using cantilever type composite transducer was proposed in this paper. There are two cantilevers on the ...

  6. A Novel Approach to the Sensing of Liquid Density Using a Plastic Optical Fibre Cantilever Beam

    Science.gov (United States)

    Kulkarni, Atul; Kim, Youngjin; Kim, Taesung

    2009-01-01

    This article reports for the first time the use of a plastic optical fibre (POF) cantilever beam to measure the density of a liquid. The sensor is based on the Archimedes buoyancy principle. The sensor consists of a POF bonded on the surface of a metal beam in the form of a cantilever configuration, and at the free end of the beam a displacer is…

  7. Micro electro-mechanical system piezoelectric cantilever array for a broadband vibration energy harvester.

    Science.gov (United States)

    Chun, Inwoo; Lee, Hyun-Woo; Kwon, Kwang-Ho

    2014-12-01

    Limited energy sources of ubiquitous sensor networks (USNs) such as fuel cells and batteries have grave drawbacks such as the need for replacements and re-charging owing to their short durability and environmental pollution. Energy harvesting which is converting environmental mechanical vibration into electrical energy has been researched with some piezoelectric materials and various cantilever designs to increase the efficiency of energy-harvesting devices. In this study, we focused on an energy-harvesting cantilever with a broadband vibration frequency. We fabricated a lead zirconate titanate (PZT) cantilever array with various Si proof masses on small beams (5.5 mm x 0.5 mm x 0.5 mm). We obtained broadband resonant frequencies ranging between 127 Hz and 136 Hz using a micro electro-mechanical system (MEMS) process. In order to obtain broadband resonant characteristics, the cantilever array was comprised of six cantilevers with different resonant frequencies. We obtained an output power of about 2.461 μW at an acceleration of 0.23 g and a resistance of 4 kΩ. The measured bandwidth of the resonant frequency was approximately 9 Hz (127-136 Hz), which is about six times wider than the bandwidth of a single cantilever.

  8. Development of Multi-Degree-Of-Freedom Piezoelectric Energy Harvester Using Interdigital Shaped Cantilevers.

    Science.gov (United States)

    Cho, Hyunok; Park, Jongcheol; Park, Jae Yeong

    2016-05-01

    A piezoelectric vibration energy harvester with interdigital shaped cantilever was developed by using silicon bulk micromachining technology. The proposed energy harvester was designed to obtain multi degree-of-freedom (m-DOF). Most of the piezoelectric vibration energy harvesters are comprised of mass-loaded cantilever beams having several resonant frequencies. The second resonant frequency of such a device has lower amplitude compared to its first resonant frequency (fundamental frequency). Therefore, the interdigital shaped cantilever has been proposed for multiple fundamental resonant frequencies. The fabricated piezoelectric vibration energy harvester is composed of main cantilever (MC), sub-main cantilever (SMC), and secondary cantilevers (SC). MC surrounds SMC and SC which have same dimension of 5600 x 800 x 10 μm3. The fabricated piezoelectric energy harvester can generate 51.4 mV(p-p) and 11 mV(p-p) of output voltages at 24.2 Hz and 33 Hz of its resonant frequencies by MC. Moreover, it can generate 8 mV(p-p) and 6.6 mV(p-p) of output voltages at 24.2 Hz and 33.2 Hz of its resonant frequencies by SMC; and 364 mV(p-p) of output voltage at 33.6 Hz of its resonant frequency by SC.

  9. Innovative multi-cantilever array sensor system with MOEMS read-out

    Science.gov (United States)

    Ivaldi, F.; Bieniek, T.; Janus, P.; Grabiec, P.; Majstrzyk, W.; Kopiec, D.; Gotszalk, T.

    2016-11-01

    Cantilever based sensor system are a well-established sensor family exploited in several every-day life applications as well as in high-end research areas. The very high sensitivity of such systems and the possibility to design and functionalize the cantilevers to create purpose built and highly selective sensors have increased the interest of the scientific community and the industry in further exploiting this promising sensors type. Optical deflection detection systems for cantilever sensors provide a reliable, flexible method for reading information from cantilevers with the highest sensitivity. However the need of using multi-cantilever arrays in several fields of application such as medicine, biology or safety related areas, make the optical method less suitable due to its structural complexity. Working in the frame of a the Joint Undertaking project Lab4MEMS II our group proposes a novel and innovative approach to solve this issue, by integrating a Micro-Opto-Electro-Mechanical-System (MOEMS) with dedicated optics, electronics and software with a MOEMS micro-mirror, ultimately developed in the frame of Lab4MEMSII. In this way we are able to present a closely packed, lightweight solution combining the advantages of standard optical read-out systems with the possibility of recording multiple read-outs from large cantilever arrays quasi simultaneously.

  10. Microdrops on atomic force microscope cantilevers: evaporation of water and spring constant calibration.

    Science.gov (United States)

    Bonaccurso, Elmar; Butt, Hans-Jürgen

    2005-01-13

    The evaporation of water drops with radii approximately 20 microm was investigated experimentally by depositing them onto atomic force microscope (AFM) cantilevers and measuring the deflection versus time. Because of the surface tension of the liquid, the Laplace pressure inside the drop, and the change of interfacial stress at the solid-liquid interface, the cantilever is deflected by typically a few hundred nanometers. The experimental results are in accordance with an analytic theory developed. The evaporation process could be monitored with high accuracy even at the last stage of evaporation because (1) cantilever deflections can be measured with nanometer resolution and (2) the time resolution, given by the inverse of the resonance frequency of the cantilever of approximately 0.3 ms, is much faster than the typical evaporation time of 1 s. Experimental results indicate that evaporation of the last thin layer of water is significantly slower than the rest of the drop, which can be due to surface forces. This drop-on-cantilever system can also be used to analyze the drop impact dynamics on a surface and to determine the spring constant of cantilevers.

  11. A theoretical and experimental study on geometric nonlinearity of initially curved cantilever beams

    Directory of Open Access Journals (Sweden)

    Sushanta Ghuku

    2016-03-01

    Full Text Available This paper presents a theoretical and experimental study on large deflection behavior of initially curved cantilever beams subjected to various types of loadings. The physical system as a straight cantilever beam subjected to a tip concentrated load is considered in this study. Nonlinear differential equations are obtained for large deflection analysis of such a straight cantilever beam, and this problem is known to involve geometrical nonlinearity. The equations are solved numerically with the help of MATLAB® computational platform to get deflection profiles of the concerned problem. These results are imposed subsequently on the center line of an initially curved beam to get theoretical load-deflection behavior of curved beam problems. To verify the theoretical model, experiment is carried out with the master leaf of a leaf spring bundle by modeling it as an initially curved cantilever beam. The effects of initial clamping and geometry variations in the eye-region are observed from experimental investigation which is commonly neglected in the mathematical formulation. Comparisons of the theoretical results with the experimental results are quite good, but the avenues for further improvement are also reported. The proposed approach is further extended to study large deflection behavior of an initially curved cantilever beam subjected to distributed and combined load. These results are successfully validated with existing results for straight beams and some new results are furnished for initially curved cantilever beams.

  12. Micromachined cantilevers-on-membrane topology for broadband vibration energy harvesting

    Science.gov (United States)

    Jia, Yu; Du, Sijun; Seshia, Ashwin A.

    2016-12-01

    The overwhelming majority of microelectromechanical piezoelectric vibration energy harvesting topologies have been based on cantilevers, doubly-clamped beams or basic membranes. While these conventional designs offer simplicity, their broadband responses have been limited thus far. This paper investigates the feasibility of a new integrated cantilevers-on-membrane design that explores the optimisation of piezoelectric strain distribution and improvement of the broadband power output. While a classic membrane has the potential to offer a broader resonant peak than its cantilever counterpart, the inclusion of a centred proof mass compromises its otherwise high strain energy regions. The proposed topology addresses this issue by relocating the proof mass onto subsidiary cantilevers and combines the merits of both the membrane and the cantilever designs. Numerical simulations, constructed using fitted values based on finite element models, were used to investigate the broadband response of the proposed design in contrast to a classic plain membrane. Experimentally, when subjected to a band-limited white noise excitation, the new cantilevers-on-membrane harvester exhibited nearly two fold power output enhancement when compared to a classic plain membrane harvester of a comparable size.

  13. In-plane load measuring technique for the strength test of MEMS micro-cantilever

    Institute of Scientific and Technical Information of China (English)

    HUAN Yong; ZHANG Taihua; YANG Yemin

    2006-01-01

    An in-plane load measuring technique is developed to perform the strength test of the micro-cantilever. Based on electromagnetism theorem,Micro UTM (Universal Testing Machine) was in-house made with the load range ±1 N and the displacement range ±300 μm. It applies an in-plane load on the free-end of the micro-cantilever. The load acts as a bending moment for the root of the cantilever, but as a torque for the anchor. The results show that for samples with different sizes the ultimate loads range from 1.3 to 69.8 mN and the calculated torque is approximately proportional to the square of the bonding length. Two failure modes, fracture at the root of the cantilever and fracture at the anchor, are observed by micro examination to the debris, which indicates that there is a critical design to achieve the strength balance between the cantilever and the anchor. The work demonstrates that Micro UTM is a powerful instrument for the strength test of the micro-cantilever and similar micro-structures.

  14. Study of node and mass sensitivity of resonant mode based cantilevers with concentrated mass loading

    Directory of Open Access Journals (Sweden)

    Kewei Zhang

    2015-12-01

    Full Text Available Resonant-mode based cantilevers are an important type of acoustic wave based mass-sensing devices. In this work, the governing vibration equation of a bi-layer resonant-mode based cantilever attached with concentrated mass is established by using a modal analysis method. The effects of resonance modes and mass loading conditions on nodes and mass sensitivity of the cantilever were theoretically studied. The results suggested that the node did not shift when concentrated mass was loaded on a specific position. Mass sensitivity of the cantilever was linearly proportional to the square of the point displacement at the mass loading position for all the resonance modes. For the first resonance mode, when mass loading position xc satisfied 0 < xc < ∼ 0.3l (l is the cantilever beam length and 0 represents the rigid end, mass sensitivity decreased as the mass increasing while the opposite trend was obtained when mass loading satisfied ∼0.3l ≤ xc ≤ l. Mass sensitivity did not change when concentrated mass was loaded at the rigid end. This work can provide scientific guidance to optimize the mass sensitivity of a resonant-mode based cantilever.

  15. Principles of Bridge Reliability

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Nowak, Andrzej S.

    The paper gives a brief introduction to the basic principles of structural reliability theory and its application to bridge engineering. Fundamental concepts like failure probability and reliability index are introduced. Ultimate as well as serviceability limit states for bridges are formulated...

  16. Nonlinear Response of Cantilever Beams to Combination and Subcombination Resonances

    Directory of Open Access Journals (Sweden)

    Ali H. Nayfeh

    1998-01-01

    Full Text Available The nonlinear planar response of cantilever metallic beams to combination parametric and external subcombination resonances is investigated, taking into account the effects of cubic geometric and inertia nonlinearities. The beams considered here are assumed to have large length-to-width aspect ratios and thin rectangular cross sections. Hence, the effects of shear deformations and rotatory inertia are neglected. For the case of combination parametric resonance, a two-mode Galerkin discretization along with Hamilton’s extended principle is used to obtain two second-order nonlinear ordinary-differential equations of motion and associated boundary conditions. Then, the method of multiple scales is applied to obtain a set of four first-order nonlinear ordinary-differential equations governing the modulation of the amplitudes and phases of the two excited modes. For the case of subcombination resonance, the method of multiple scales is applied directly to the Lagrangian and virtual-work term. Then using Hamilton’s extended principle, we obtain a set of four first-order nonlinear ordinary-differential equations governing the amplitudes and phases of the two excited modes. In both cases, the modulation equations are used to generate frequency- and force-response curves. We found that the trivial solution exhibits a jump as it undergoes a subcritical pitchfork bifurcation. Similarly, the nontrivial solutions also exhibit jumps as they undergo saddle-node bifurcations.

  17. A single nano cantilever as a reprogrammable universal logic gate

    Science.gov (United States)

    Chappanda, K. N.; Ilyas, S.; Kazmi, S. N. R.; Holguin-Lerma, J.; Batra, N. M.; Costa, P. M. F. J.; Younis, M. I.

    2017-04-01

    The current transistor-based computing circuits use multiple interconnected transistors to realize a single Boolean logic gate. This leads to higher power requirements and delayed computing. Transistors are not suitable for applications in harsh environments and require complicated thermal management systems due to excessive heat dissipation. Also, transistor circuits lack the ability to dynamically reconfigure their functionality in real time, which is desirable for enhanced computing capability. Further, the miniaturization of transistors to improve computational power is reaching its ultimate physical limits. As a step towards overcoming the limitations of transistor-based computing, here we demonstrate a reprogrammable universal Boolean logic gate based on a nanoelectromechanical cantilever (NC) oscillator. The fundamental XOR, AND, NOR, OR and NOT logic gates are condensed in a single NC, thereby reducing electrical interconnects between devices. The device is dynamically switchable between any logic gates at the same drive frequency without the need for any change in the circuit. It is demonstrated to operate at elevated temperatures minimizing the need for thermal management systems. It has a tunable bandwidth of 5 MHz enabling parallel and dynamically reconfigurable logic device for enhanced computing.

  18. Non-Linear Piezoelectric Actuator with a Preloaded Cantilever Beam

    Directory of Open Access Journals (Sweden)

    Yue Wu

    2015-08-01

    Full Text Available Piezoelectric actuation is widely used for the active vibration control of smart structural systems, and corresponding research has largely focused on linear electromechanical devices. This paper investigates the design and analysis of a novel piezoelectric actuator that uses a piezoelectric cantilever beam with a loading spring to produce displacement outputs. This device has a special nonlinear property relating to converting between kinetic energy and potential energy, and it can be used to increase the output displacement at a lower voltage. The system is analytically modeled with Lagrangian functional and Euler–Lagrange equations, numerically simulated with MATLAB, and experimentally realized to demonstrate its enhanced capabilities. The model is validated using an experimental device with several pretensions of the loading spring, therein representing three interesting cases: a linear system, a low natural frequency system with a pre-buckled beam, and a system with a buckled beam. The motivating hypothesis for the current work is that nonlinear phenomena could be exploited to improve the effectiveness of the piezoelectric actuator’s displacement output. The most practical configuration seems to be the pre-buckled case, in which the proposed system has a low natural frequency, a high tip displacement, and a stable balanced position.

  19. MODAL TEST AND ANALYSIS OF CANTILEVER BEAM WITH TIP MASS

    Institute of Scientific and Technical Information of China (English)

    肖世富; 杜强; 陈滨; 刘才山; 向荣山; 周为华; 徐友钜; 徐有刚

    2002-01-01

    The phenomenon of dynamic stiffening is a research field of general interest for flexible multi-body systems. In fact, there are not only dynamic stiffening but also dynamic softening phenomenon in the flexible multi-body systems. In this paper, a non-linear dynamic model and its linearization characteristic equations of a cantilever beam with tip mass in the centrifugal field are established by adopting the general Hamilton Variational Principle. Then, the problems of the dynamic stiffening and the dynamic softening are studied by using numerical simulations. Meanwhile,the modal test is carried out on our centrifuge. The numerical results show that the system stiffness will be strengthened when the centrifugal tension force acts on the beam (i.e. the dynamic stiffening). However, the system stiffness will be weakened when the centrifugal compression force acts on the beam (i.e. the dynamic softening).Furthermore, the equilibrium position of the system will lose its stability when the inertial force reaches a critical value. Through theoretical analysis, we find that this phenomenon comes from the effect of dynamic softening resulting from the centrifugal compression force. Our test results verify the above conclusions and confirm that both dynamic stiffening and softening phenomena exist in flexible multi-body systems.

  20. Advanced structural optimization of a heliostat with cantilever arms

    Science.gov (United States)

    Bogdanov, Dimitar; Zlatanov, Hristo

    2016-05-01

    The weight of the support structure of heliostats, CPV and PV trackers is important cost element of a solar plant and reducing it will improve the economic viability of a solar project. Heliostats with rectangular area (1 to 5 in 1 m² steps; 5 to 150 in 5 m² steps) and aspect ratios (0.5, 1.0, 1.2, 1.5, 2.0) were investigated under various winds speeds (0, 5 to 100 in 5 m/s steps), wind direction (0 to 180° in 15° steps) and elevation positions (0 to 90° in 10° steps). Each load case was run with three different cantilever arms. The inclination angle of the chords and bracings was chosen so as to fulfill the geometrical boundary condition. Stress and buckling validations were performed according to Eurocode. The results of research carried out can be used to determine the specific weight of a heliostat in kg/m² as a function of the wind speed, tracker area and tracker aspect ratio. Future work should investigate the impact of using cold formed structural hollow sections and cross sections with thinner wall thickness which is not part of EN 10210.

  1. An Experimental and Theoretical Investigation of Electrostatically Coupled Cantilever Microbeams

    KAUST Repository

    Ilyas, Saad

    2016-06-16

    We present an experimental and theoretical investigation of the static and dynamic behavior of electrostatically coupled laterally actuated silicon microbeams. The coupled beam resonators are composed of two almost identical flexible cantilever beams forming the two sides of a capacitor. The experimental and theoretical analysis of the coupled system is carried out and compared against the results of beams actuated with fixed electrodes individually. The pull-in characteristics of the electrostatically coupled beams are studied, including the pull-in time. The dynamics of the coupled dual beams are explored via frequency sweeps around the neighborhood of the natural frequencies of the system for different input voltages. Good agreement is reported among the simulation results and the experimental data. The results show considerable drop in the pull-in values as compared to single microbeam resonators. The dynamics of the coupled beam resonators are demonstrated as a way to increase the bandwidth of the resonator near primary resonance as well as a way to introduce increased frequency shift, which can be promising for resonant sensing applications. Moreover the dynamic pull-in characteristics are also studied and proposed as a way to sense the shift in resonance frequency.

  2. Flexible SiO2 cantilevers for torsional self-aligning micro scale four-point probes

    DEFF Research Database (Denmark)

    Kjær, Daniel; Gammelgaard, Lauge; Bøggild, Peter;

    2007-01-01

    to compensate for misalignment is improved at a cost of reduced spring constant. Analytical calculations, numerical simulations on cantilever deflection and comparison with experimental results indicate that a reasonable compromise between torsional flexibility and overall spring constant can be achieved...... by proper dimensioning and placement of the hinge. Furthermore, it is shown that polymeric macro scale cantilever models can provide a fast and reliable understanding of the mechanical deflection properties of microfabricated SiO2 cantilevers....

  3. SU-8 cantilevers for bio/chemical sensing; Fabrication, characterisation and development of novel read-out methods

    DEFF Research Database (Denmark)

    Nordström, M.; Keller, Stephan Urs; Lillemose, Michael;

    2008-01-01

    Here, we present the activities within our research group over the last five years with cantilevers fabricated in the polymer SU-8. We believe that SU-8 is an interesting polymer for fabrication of cantilevers for bio/chemical sensing due to its simple processing and low Young's modulus. We show...... examples of different integrated read-out methods and their characterisation. We also show that SU-8 cantilevers have a reduced sensitivity to changes in the environmental temperature and pH of the buffer solution. Moreover, we show that the SU-8 cantilever surface can be functionalised directly...

  4. Research on the special lifting devices for steel box girders of Sutong Bridge

    Institute of Scientific and Technical Information of China (English)

    Chen Ming; Wu Qihe; Luo Chengbin; Zhou Hanfa

    2009-01-01

    Sutong Bridge is a cable-stayed bridge with a steel box girder and a main span of 1 088 m. The steel box girder of main span includes five portions: back span large unit, large block of pylon, standard girder, back span closure girder and middle span closure girder. Each back span large unit is fabricated by welding several deck segments together in factory, and is erected by floating crane. As navigational clearance of the main bridge is high, the traditional truss lifting device can' t satisfy the requirement of domestic lifting cranes for this kind of lifting height and weight. Hence, a kind of lighter lifting device for the erection of back span large units was accepted for this bridge. In this paper, the design and use of this lifting device is introduced.The upper structure used lifting gantry to install the standard girder segment by cantilever method. Because the bridge's navigation clearance is high, and the girder segment is wide and heavy, the meteorology and hydrology condition of the bridge district is abominable, and the requirements of long cable girder side pull-in, structure and performance propose high request to the lifting gantry. In this paper, the design and use key point of long cable pull-in angle adjustment device integrate into lifting gantry is introduced.

  5. Bridge technology report

    CERN Document Server

    2013-01-01

    Please note this is a Short Discount publication. As LANs have proliferated, new technologies and system concepts have come to the fore. One of the key issues is how to interconnect networks. One means of interconnection is to use a 'bridge'. Other competing technologies are repeaters, routers, and gateways. Bridges permit traffic isolation, connect network segments together and operate at the MAC layer. Further, because they operate at the MAC layer, they can handle a variety of protocols such as TCP/IP, SNA, and X.25. This report focuses on the specific technology of bridging two netw

  6. MicroCantilever (MC) based nanomechanical sensor for detection of molecular interactions

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Kyung [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    Specific aims of this study are to investigate the mechanism governing surface stress generation associated with chemical or molecular binding on functionalized microcantilevers. Formation of affinity complexes on cantilever surfaces leads to charge redistribution, configurational change and steric hindrance between neighboring molecules resulting in surface stress change and measureable cantilever deformation. A novel interferometry technique employing two adjacent micromachined cantilevers (a sensing/reference pair) was utilized to measure the cantilever deformation. The sensing principle is that binding/reaction of specific chemical or biological species on the sensing cantilever transduces to mechanical deformation. The differential bending of the sensing cantilever respect to the reference cantilever ensures that measured response is insensitive to environmental disturbances. As a proof of principle for the measurement technique, surface stress changes associated with: self-assembly of alkanethiol, hybridization of ssDNA, and the formation of cocaine-aptamer complexes were measured. Dissociation constant (Kd) for each molecular reaction was utilized to estimate the surface coverage of affinity complexes. In the cases of DNA hybridization and cocaine-aptamer binding, measured surface stress was found to be dependent on the surface coverage of the affinity complexes. In order to achieve a better sensitivity for DNA hybridization, immobilization of receptor molecules was modified to enhance the deformation of underlying surface. Single-stranded DNA (ssDNA) strands with thiol-modification on both 3-foot and 5-foot ends were immobilized on the gold surface such that both ends are attached to the gold surface. Immobilization condition was controlled to obtain similar receptor density as single-thiolated DNA strands. Hybridization of double-thiolated DNA strands leads to an almost two orders of magnitude increase in cantilever deformation. In both DNA

  7. Bridged Race Population Estimates

    Data.gov (United States)

    U.S. Department of Health & Human Services — Population estimates from "bridging" the 31 race categories used in Census 2000, as specified in the 1997 Office of Management and Budget (OMB) race and ethnicity...

  8. Bridging Humanism and Behaviorism.

    Science.gov (United States)

    Chu, Lily

    1980-01-01

    Humanistic behaviorism may provide the necessary bridge between behaviorism and humanism. Perhaps the most humanistic approach to teaching is to learn how certain changes will help students and how these changes can be accomplished. (Author/MLF)

  9. Fabrication and characterization of large arrays of mesoscopic gold rings on large-aspect-ratio cantilevers

    Energy Technology Data Exchange (ETDEWEB)

    Ngo, D. Q.; Petković, I., E-mail: ivana.petkovic@yale.edu; Lollo, A. [Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); Castellanos-Beltran, M. A. [National Institute for Standards and Technology, Boulder, Colorado 80305 (United States); Harris, J. G. E. [Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States)

    2014-10-15

    We have fabricated large arrays of mesoscopic metal rings on ultrasensitive cantilevers. The arrays are defined by electron beam lithography and contain up to 10{sup 5} rings. The rings have a circumference of 1 μm, and are made of ultrapure (6N) Au that is deposited onto a silicon-on-insulator wafer without an adhesion layer. Subsequent processing of the SOI wafer results in each array being supported at the end of a free-standing cantilever. To accommodate the large arrays while maintaining a low spring constant, the cantilevers are nearly 1 mm in both lateral dimensions and 100 nm thick. The extreme aspect ratio of the cantilevers, the large array size, and the absence of a sticking layer are intended to enable measurements of the rings' average persistent current in the presence of relatively small magnetic fields. We describe the motivation for these measurements, the fabrication of the devices, and the characterization of the cantilevers' mechanical properties. We also discuss the devices' expected performance in measurements of .

  10. Measurement and reliability issues in resonant mode cantilever for bio-sensing application in fluid medium

    Science.gov (United States)

    Kathel, G.; Shajahan, M. S.; Bhadra, P.; Prabhakar, A.; Chadha, A.; Bhattacharya, E.

    2016-09-01

    Cantilevers immersed in liquid experience viscous damping and hydrodynamic loading. We report on the use of such cantilevers, operating in the dynamic mode with, (i) frequency sweeping and (ii) phase locked loop methods. The solution to reliability issues such as random drift in the resonant peak values, and interference of spurious modes in the resonance frequency spectrum, are explained based on the actuation signal provided and laser spot size. The laser beam spot size and its position on the cantilever were found to have an important role, on the output signal and resonance frequency. We describe a method to distinguish the normal modes from the spurious modes for a cantilever. Uncertainties in the measurements define the lower limit of mass detection (m min). The minimum detection limits of the two measurement methods are investigated by measuring salt adsorption from phosphate buffer solution, as an example, a mass of 14 pg was measured using the 14th transverse mode of a 500~μ m  ×  100 μm  ×  1 μm silicon cantilever. The optimized measurement was used to study the interaction between antibody and antigen.

  11. Performance Analysis of Wind-Induced Piezoelectric Vibration Bimorph Cantilever for Rotating Machinery

    Directory of Open Access Journals (Sweden)

    Gongbo Zhou

    2015-01-01

    Full Text Available Harvesting the energy contained in the running environment of rotating machinery would be a good way to supplement energy to the wireless sensor. In this paper, we take piezoelectric bimorph cantilever beam with parallel connection mode as energy collector and analyze the factors which can influence the generation performance. First, a modal response theory model is built. Second, the static analysis, modal analysis, and piezoelectric harmonic response analysis of the wind-induced piezoelectric bimorph cantilever beam are given in detail. Finally, an experiment is also conducted. The results show that wind-induced piezoelectric bimorph cantilever beam has low resonant frequency and stable output under the first modal mode and can achieve the maximum output voltage under the resonant condition. The output voltage increases with the increase of the length and width of wind-induced piezoelectric bimorph cantilever beam, but the latter increasing amplitude is relatively smaller. In addition, the output voltage decreases with the increase of the thickness and the ratio of metal substrate to piezoelectric patches thickness. The experiment showed that the voltage amplitude generated by the piezoelectric bimorph cantilever beam can reach the value simulated in ANSYS, which is suitable for actual working conditions.

  12. Integrated optical read-out for polymeric cantilever-based sensors

    DEFF Research Database (Denmark)

    Tenje, Maria

    2007-01-01

    This thesis presents a novel read-out method developed for cantilever-based sensors. Cantilevers are thin beams clamped at one end and during the last 10 years they have emerged as an interesting new type of bio/chemical sensor. The specific recognition of a chemical manifests itself as a bending...... detectable cantilever deflection in the transmission mode is measured as 45 nm, which compares well with the calculated value of 30 nm. Proof-of-principle is shown for the reflection mode as well but no conclusive value can be determined for the read-out sensitivity. It is believed both these novel...... Young’s modulus instead of the conventional materials Si and Si3N4. Here, a novel read-out method is presented where optical waveguides are used to integrate the light into the cantilever. It is an all-polymer device where both the cantilever and the waveguides are fabricated in the negative resist SU-8...

  13. Numerical investigation of band gaps in 3D printed cantilever-in-mass metamaterials

    Science.gov (United States)

    Qureshi, Awais; Li, Bing; Tan, K. T.

    2016-06-01

    In this research, the negative effective mass behavior of elastic/mechanical metamaterials is exhibited by a cantilever-in-mass structure as a proposed design for creating frequency stopping band gaps, based on local resonance of the internal structure. The mass-in-mass unit cell model is transformed into a cantilever-in-mass model using the Bernoulli-Euler beam theory. An analytical model of the cantilever-in-mass structure is derived and the effects of geometrical dimensions and material parameters to create frequency band gaps are examined. A two-dimensional finite element model is created to validate the analytical results, and excellent agreement is achieved. The analytical model establishes an easily tunable metamaterial design to realize wave attenuation based on locally resonant frequency. To demonstrate feasibility for 3D printing, the analytical model is employed to design and fabricate 3D printable mechanical metamaterial. A three-dimensional numerical experiment is performed using COMSOL Multiphysics to validate the wave attenuation performance. Results show that the cantilever-in-mass metamaterial is capable of mitigating stress waves at the desired resonance frequency. Our study successfully presents the use of one constituent material to create a 3D printed cantilever-in-mass metamaterial with negative effective mass density for stress wave mitigation purposes.

  14. Efficiency improvement in the cantilever photothermal excitation method using a photothermal conversion layer

    Directory of Open Access Journals (Sweden)

    Natsumi Inada

    2016-03-01

    Full Text Available Photothermal excitation is a cantilever excitation method that enables stable and accurate operation for dynamic-mode AFM measurements. However, the low excitation efficiency of the method has often limited its application in practical studies. In this study, we propose a method for improving the photothermal excitation efficiency by coating cantilever backside surface near its fixed end with colloidal graphite as a photothermal conversion (PTC layer. The excitation efficiency for a standard cantilever of PPP-NCHAuD with a spring constant of ≈40 N/m and a relatively stiff cantilever of AC55 with a spring constant of ≈140 N/m were improved by 6.1 times and 2.5 times, respectively, by coating with a PTC layer. We experimentally demonstrate high stability of the PTC layer in liquid by AFM imaging of a mica surface with atomic resolution in phosphate buffer saline solution for more than 2 h without any indication of possible contamination from the coating. The proposed method, using a PTC layer made of colloidal graphite, greatly enhances photothermal excitation efficiency even for a relatively stiff cantilever in liquid.

  15. Acoustofluidic particle trapping, manipulation, and release using dynamic-mode cantilever sensors.

    Science.gov (United States)

    Johnson, Blake N; Mutharasan, Raj

    2016-12-19

    We show here that dynamic-mode cantilever sensors enable acoustofluidic fluid mixing and trapping of suspended particles as well as the rapid manipulation and release of trapped micro-particles via mode switching in liquid. Resonant modes of piezoelectric cantilever sensors over the 0 to 8 MHz frequency range are investigated. Sensor impedance response, flow visualization studies using dye and micro-particle tracers (100 μm diameter), and finite element simulations of cantilever modal mechanics and acoustic streaming show fluid mixing and particle trapping configurations depend on the resonant mode shape. We found trapped particles could be: (1) rapidly manipulated on millimeter length scales, and (2) released from the cantilever surface after trapping by switching between low- and high-order resonant modes (less than 250 kHz and greater than 1 MHz, respectively). Such results suggest a potentially promising future for dynamic-mode cantilevers in separations, pumping and mixing applications as well as acoustofluidic-enhanced sensing applications.

  16. Signal enhancement in cantilever magnetometry based on a co-resonantly coupled sensor

    Science.gov (United States)

    Körner, Julia; Reiche, Christopher F; Gemming, Thomas; Büchner, Bernd; Gerlach, Gerald

    2016-01-01

    Summary Cantilever magnetometry is a measurement technique used to study magnetic nanoparticles. With decreasing sample size, the signal strength is significantly reduced, requiring advances of the technique. Ultrathin and slender cantilevers can address this challenge but lead to increased complexity of detection. We present an approach based on the co-resonant coupling of a micro- and a nanometer-sized cantilever. Via matching of the resonance frequencies of the two subsystems we induce a strong interplay between the oscillations of the two cantilevers, allowing for a detection of interactions between the sensitive nanocantilever and external influences in the amplitude response curve of the microcantilever. In our magnetometry experiment we used an iron-filled carbon nanotube acting simultaneously as nanocantilever and magnetic sample. Measurements revealed an enhancement of the commonly used frequency shift signal by five orders of magnitude compared to conventional cantilever magnetometry experiments with similar nanomagnets. With this experiment we do not only demonstrate the functionality of our sensor design but also its potential for very sensitive magnetometry measurements while maintaining a facile oscillation detection with a conventional microcantilever setup. PMID:27547621

  17. Design of piezoelectric MEMS cantilever for low-frequency vibration energy harvester

    Science.gov (United States)

    Takei, Ryohei; Makimoto, Natsumi; Okada, Hironao; Itoh, Toshihiro; Kobayashi, Takeshi

    2016-06-01

    We report the design of piezoelectric MEMS cantilevers formed on a silicon-on-insulator wafer to efficiently harvest electrical power from harmonic vibration with a frequency of approximately 30 Hz. Numerical simulation indicates that a >4-µm-thick top silicon layer and >3-µm-thick piezoelectric film are preferable to maximize the output electrical power. An in-plane structure of the cantilever is also designed retaining the footprint of the cantilever. The simulation results indicate that the output power is maximized when the length ratio of the proof mass to the cantilever beam is 1.5. To ensure the accuracy of the simulation, we fabricated and characterized cantilevers with a 10-µm-thick top silicon layer and a 1.8-µm-thick piezoelectric film, resulting in 0.21 µW at a vibration of 0.5 m/s2 and 25.1 Hz. The measured output power is in agreement with the simulated value, meaning that the design is significantly reliable for low-frequency vibration energy harvesters.

  18. Design Optimization of PZT-Based Piezoelectric Cantilever Beam by Using Computational Experiments

    Science.gov (United States)

    Kim, Jihoon; Park, Sanghyun; Lim, Woochul; Jang, Junyong; Lee, Tae Hee; Hong, Seong Kwang; Song, Yewon; Sung, Tae Hyun

    2016-08-01

    Piezoelectric energy harvesting is gaining huge research interest since it provides high power density and has real-life applicability. However, investigative research for the mechanical-electrical coupling phenomenon remains challenging. Many researchers depend on physical experiments to choose devices with the best performance which meet design objectives through case analysis; this involves high design costs. This study aims to develop a practical model using computer simulations and to propose an optimized design for a lead zirconate titanate (PZT)-based piezoelectric cantilever beam which is widely used in energy harvesting. In this study, the commercial finite element (FE) software is used to predict the voltage generated from vibrations of the PZT-based piezoelectric cantilever beam. Because the initial FE model differs from physical experiments, the model is calibrated by multi-objective optimization to increase the accuracy of the predictions. We collect data from physical experiments using the cantilever beam and use these experimental results in the calibration process. Since dynamic analysis in the FE analysis of the piezoelectric cantilever beam with a dense step size is considerably time-consuming, a surrogate model is employed for efficient optimization. Through the design optimization of the PZT-based piezoelectric cantilever beam, a high-performance piezoelectric device was developed. The sensitivity of the variables at the optimum design is analyzed to suggest a further improved device.

  19. Efficiency improvement in the cantilever photothermal excitation method using a photothermal conversion layer.

    Science.gov (United States)

    Inada, Natsumi; Asakawa, Hitoshi; Kobayashi, Taiki; Fukuma, Takeshi

    2016-01-01

    Photothermal excitation is a cantilever excitation method that enables stable and accurate operation for dynamic-mode AFM measurements. However, the low excitation efficiency of the method has often limited its application in practical studies. In this study, we propose a method for improving the photothermal excitation efficiency by coating cantilever backside surface near its fixed end with colloidal graphite as a photothermal conversion (PTC) layer. The excitation efficiency for a standard cantilever of PPP-NCHAuD with a spring constant of ≈40 N/m and a relatively stiff cantilever of AC55 with a spring constant of ≈140 N/m were improved by 6.1 times and 2.5 times, respectively, by coating with a PTC layer. We experimentally demonstrate high stability of the PTC layer in liquid by AFM imaging of a mica surface with atomic resolution in phosphate buffer saline solution for more than 2 h without any indication of possible contamination from the coating. The proposed method, using a PTC layer made of colloidal graphite, greatly enhances photothermal excitation efficiency even for a relatively stiff cantilever in liquid.

  20. Optomechanical transduction of an integrated silicon cantilever probe using a microdisk resonator

    CERN Document Server

    Srinivasan, Kartik; Rakher, Matthew T; Davanco, Marcelo; Aksyuk, Vladimir

    2010-01-01

    Sensitive transduction of the motion of a microscale cantilever is central to many applications in mass, force, magnetic resonance, and displacement sensing. Reducing cantilever size to nanoscale dimensions can improve the bandwidth and sensitivity of techniques like atomic force microscopy, but current optical transduction methods suffer when the cantilever is small compared to the achievable spot size. Here, we demonstrate sensitive optical transduction in a monolithic cavity-optomechanical system in which a sub-picogram silicon cantilever with a sharp probe tip is separated from a microdisk optical resonator by a nanoscale gap. High quality factor (Q ~ 10^5) microdisk optical modes transduce the cantilever's MHz frequency thermally-driven vibrations with a displacement sensitivity of ~ 4.4x10^-16 m\\sqrt[2]{Hz} and bandwidth > 1 GHz, and a dynamic range > 10^6 is estimated for a 1 s measurement. Optically-induced stiffening due to the strong optomechanical interaction is observed, and engineering of probe d...

  1. Cantilever-based mass sensor for immunodetection of multiple bioactive targets

    Science.gov (United States)

    Tang, Tang; Xu, Bai; Welch, John; Castracane, James

    2004-01-01

    We are investigating the development of a rapid and highly sensitive detection method for immunoreactive substances combining MEMS (Micro Electro Mechanical Systems) technology and the appropriate immune stimulant or response factors. Cantilevers of micrometer scale can be used for trace detection of mass change. When a layer of an antigenic substance is covalently deposited, the cantilever is capable of capturing antibodies from samples with high affinity and specificity. The antigen/antibody binding causes multiple physical changes in the cantilever device, including a shift of effective mass and a change in surface tension. The change of effective mass consequently induces a shift in the cantilever"s natural resonant frequency. By monitoring these changes with an optical readout mechanism, the presence of immunoreactive targets in the sample can be detected. This detection method can be used for various types of targets with immunoreactivity and therefore is potentially applicable in hazardous substance monitoring and disease diagnosis. In our effort, phoS1, an antigen shed by Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is utilized for rapid and economic TB detection.

  2. Decision-making for treatment planning a cantilevered fixed partial denture.

    Science.gov (United States)

    Hill, Edward E

    2009-01-01

    Considerable controversy exists in the dental literature regarding cantilevered pontics. This article discusses basic concepts of the cantilever fixed partial denture (CFPD) in which one cantilevered pontic is supported by only one or two abutment teeth. Three primary factors should be considered carefully to optimize the prognosis for a CFPD: abutment selection, control of functional forces, and rigidity/strength of connectors. Abutments should have a root surface area greater than the tooth being replaced and a crown-to-root ratio of 2:3. They also should exhibit minimal mobility and be vital and periodontally sound. Contact on cantilevered pontics should be light in centric position and nonexistent in excursions. CFPDs ideally should be metal or metal-ceramic, and connectors, which are high-stress areas, require bulk for strength. A cantilevered prosthesis may require more consideration and planning than a conventional fixed partial denture, but when kept within the patient's biological limitations and executed properly, can provide a restorative option with many advantages.

  3. Germ Cell Intercellular Bridges

    Science.gov (United States)

    Greenbaum, Michael P.; Iwamori, Tokuko; Buchold, Gregory M.; Matzuk, Martin M.

    2011-01-01

    Stable intercellular bridges are a conserved feature of gametogenesis in multicellular animals observed more than 100 years ago, but their function was unknown. Many of the components necessary for this structure have been identified through the study of cytokinesis in Drosophila; however, mammalian intercellular bridges have distinct properties from those of insects. Mammalian germ cell intercellular bridges are composed of general cytokinesis components with additional germ cell–specific factors including TEX14. TEX14 is an inactive kinase essential for the maintenance of stable intercellular bridges in gametes of both sexes but whose loss specifically impairs male meiosis. TEX14 acts to impede the terminal steps of abscission by competing for essential component CEP55, blocking its interaction in nongerm cells with ALIX and TSG101. Additionally, TEX14-interacting protein RBM44, whose localization in stabile intercellular bridges is limited to pachytene and secondary spermatocytes, may participate in processes such as RNA transport but is nonessential to the maintenance of intercellular bridge stability. PMID:21669984

  4. Long Span Bridges in Scandinavia

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    1998-01-01

    The first Scandinavian bridge with a span of more than 500 m was the Lillebælt Suspension Bridge opened to traffic in 1970.Art the end of the 20th century the longest span of any European bridge is found in the Storebælt East Bridge with a main span of 1624 m. Also the third longest span in Europe...... is found in Scandinavia - the 1210 m span of the Höga Kusten Bridge in Sweden.The Kvarnsund Bridge in Norway was at the completion in 1991 the longest cable-stayed bridge in the world, and the span of 530 m is still thge longest for cable-stayed bridges in concrete. The Øresund Bridge with its sapn of 490...... m is the longest among cable-stayed bridges for both road and railway traffic....

  5. ABNORMAL BENDING OF MICRO-CANTILEVER PLATE INDUCECD BY A DROPLET

    Institute of Scientific and Technical Information of China (English)

    Jianlin Liu; Xueyan Zhu; Xinkang Li; Zhiwei Li

    2010-01-01

    The abnormal bending of a micro-cantilever plate induced by a droplet is of great interest and of significance in micro/nano-manipulations.In this study,the physical mechanism of this abnormal phenomenon induced by an actual droplet is elucidated.Firstly,the morphologies of 2D and 3D droplets are solved analytically or numerically.Then the Laplace pressure difference acting on the cantilever plate caused by the droplet is presented.Finally,the deflections of the micro-cantilever plates driven by the capillary forces are quantitatively analyzed.These analytical results may be beneficial to some engineering applications,such as micro-sensors,MEMS and the micro/nano-measurement.

  6. Design and Simulation of Array of Rectangular Micro Cantilevers Piezoelectric Energy Harvester

    Directory of Open Access Journals (Sweden)

    Komal Kumari

    2016-09-01

    Full Text Available This paper presents the design, analysis and simulation of MEMS based array of bimorph rectangular microcantilever piezoelectric energy harvester structure with and without tip mass, to analyze their sensitivity. The microcantilever beams are made up of piezoelectric material and Aluminium as a substrate material. The analytical simulation of design is done by FEM (COMSOL Multiphysics. The simulation results of bimorph cantilever structure, applied force of 0.1 N and obtained end displacement and electric potential developed are given. The analytical model of the cantilever beam will be analyzed and the process of its construction will be discussed. The changes in the sensitivity of a cantilever beam with respect to change in its shape for the same applied force of 0.1N are denoted.

  7. Highly sensitive polymer-based cantilever-sensors for DNA detection

    Energy Technology Data Exchange (ETDEWEB)

    Calleja, M. [Biosensors Group, Nacional Center of Microelectronics (CNM-CSIC), Isaac Newton 8, Tres Cantos, E-28760 Madrid (Spain) and Mikroelektronics Centret, Technical University of Denmark, 345E, DK-2800, Lyngby (Denmark)]. E-mail: mcalleja@imm.cnm.csic.es; Nordstroem, M. [Mikroelektronics Centret, Technical University of Denmark, 345E, DK-2800, Lyngby (Denmark); Alvarez, M. [Biosensors Group, Nacional Center of Microelectronics (CNM-CSIC), Isaac Newton 8, Tres Cantos, E-28760 Madrid (Spain); Tamayo, J. [Biosensors Group, Nacional Center of Microelectronics (CNM-CSIC), Isaac Newton 8, Tres Cantos, E-28760 Madrid (Spain); Lechuga, L.M. [Biosensors Group, Nacional Center of Microelectronics (CNM-CSIC), Isaac Newton 8, Tres Cantos, E-28760 Madrid (Spain); Boisen, A. [Mikroelektronics Centret, Technical University of Denmark, 345E, DK-2800, Lyngby (Denmark)

    2005-11-15

    We present a technology for the fabrication of cantilever arrays aimed to develop an integrated biosensor microsystem. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. Arrays of up to 33 microcantilevers are fabricated in the novel polymer material SU-8. The low Young's modulus of the polymer, 40 times lower than that of silicon, enables to improve the sensitivity of the sensor device for target detection. The mechanical properties of SU-8 cantilevers, such as spring constant, resonant frequency and quality factor are characterized as a function of the dimensions and the medium. The devices have been tested for measurement of the adsorption of single stranded DNA and subsequent interstitial adsorption of lateral spacer molecules. We demonstrate that sensitivity is enhanced by a factor of six compared to that of commercial silicon nitride cantilevers.

  8. Lattice Boltzmann Simulation of the Cross Flow Over a Cantilevered and Longitudinally Vibrating Circular Cylinder

    Institute of Scientific and Technical Information of China (English)

    XIA Yong; LU De-Tang; LIU Yang; XU You-Sheng

    2009-01-01

    The multiple-relaxation-time lattice Boltzmann method (MRT-LBM) is implemented to numerically simulate the cross flow over a longitudinal vibrating circular cylinder.This research is carried out on a three-dimensional (3D) finite cantilevered cylinder to investigate the effect of forced vibration on the wake characteristics and the 319 effect of a cantilevered cylinder.To meet the accuracy of this method,the present calculation is carried out at a low Reynolds number Re = 100,as well as to make the vibration obvious,we make the vibration strong enough.The calculation results indicate that the vibration has significant influence on the wake characteristics. When the vibrating is big enough,our early works show that the 2D vortex shedding would be locked up by vibration.Contrarily,this phenomenon would not appear in the present 313 case because of the end effect of the cantilevered cylinder.

  9. Active vibration control of flexible cantilever plates using piezoelectric materials and artificial neural networks

    Science.gov (United States)

    Abdeljaber, Osama; Avci, Onur; Inman, Daniel J.

    2016-02-01

    The study presented in this paper introduces a new intelligent methodology to mitigate the vibration response of flexible cantilever plates. The use of the piezoelectric sensor/actuator pairs for active control of plates is discussed. An intelligent neural network based controller is designed to control the optimal voltage applied on the piezoelectric patches. The control technique utilizes a neurocontroller along with a Kalman Filter to compute the appropriate actuator command. The neurocontroller is trained based on an algorithm that incorporates a set of emulator neural networks which are also trained to predict the future response of the cantilever plate. Then, the neurocontroller is evaluated by comparing the uncontrolled and controlled responses under several types of dynamic excitations. It is observed that the neurocontroller reduced the vibration response of the flexible cantilever plate significantly; the results demonstrated the success and robustness of the neurocontroller independent of the type and distribution of the excitation force.

  10. Gravimetric measurements with use of a cantilever for controlling of electrochemical deposition processes

    Science.gov (United States)

    Prokaryn, Piotr; Janus, Pawel; Zajac, Jerzy; Sierakowski, Andrzej; Domanski, Krzysztof; Grabiec, Piotr

    2016-11-01

    In this paper we describe the method for monitoring the progress of electrochemical deposition process. The procedure allows to control the deposition of metals as well as conductive polymers on metallic seed layer. The method is particularly useful to very thin layers (1-10 nm) of deposited medium which mechanical or optical methods are troublesome for. In this method deposit is grown on the target and on the test silicon micro-cantilever with a metal pad. Galvanic deposition on the cantilever causes the change of its mass and consequently the change of its resonance frequency. Changes of the frequency is measured with laser vibro-meter then the layer thicknesses can be estimated basing on the cantilever calibration curve. Applying this method for controlling of gold deposition on platinum seed layer, for improving the properties of the biochemical sensors, is described in this paper.

  11. Ultrasensitive measurement of MEMS cantilever displacement sensitivity below the shot noise limit

    CERN Document Server

    Pooser, R C

    2014-01-01

    The displacement of micro-electro-mechanical-systems(MEMs) cantilevers is used to measure a variety of phenomena in devices ranging from force microscopes for single spin detection[1] to biochemical sensors[2] to uncooled thermal imaging systems[3]. The displacement readout is often performed optically with segmented detectors or interference measurements. Until recently, various noise sources have limited the minimum detectable displacement in MEMs systems, but it is now possible to minimize all other sources[4] so that the noise level of the coherent light field, called the shot noise limit(SNL), becomes the dominant source. Light sources dis- playing quantum-enhanced statistics below this limit are available[5, 6], with applications in gravitational wave astronomy[7] and bioimaging[8], but direct displacement measurements of MEMS cantilevers below the SNL have been impossible until now. Here, we demonstrate the first direct measurement of a MEMs cantilever displacement with sub-SNL sensitivity, thus enabli...

  12. Wide frequency range capacitive detection of loss in a metallic cantilever using resonance and relaxation modes.

    Science.gov (United States)

    Richert, Ranko

    2007-05-01

    The impedance of a capacitor which embraces a charged cantilever is used to measure the mechanical properties of the cantilever material. The technique has been tested with an amorphous metallic specimen, but is applicable for many other solids. The material damping can be measured at the resonance frequency of the cantilever via the width of the resonance curve or by recording the ring-down behavior. Additionally, several decades in frequency are accessible below the resonance frequency, where values as low as nu=0.03 Hz are achieved easily. The data are analyzed with a single equation that captures the damping at all frequencies in terms of the material specific Young's modulus E and its loss angle tan delta=E"/E'.

  13. Nano-Workbench: A Combined Hollow AFM Cantilever and Robotic Manipulator

    Directory of Open Access Journals (Sweden)

    Héctor Hugo Pérez Garza

    2015-05-01

    Full Text Available To manipulate liquid matter at the nanometer scale, we have developed a robotic assembly equipped with a hollow atomic force microscope (AFM cantilever that can handle femtolitre volumes of liquid. The assembly consists of four independent robots, each sugar cube sized with four degrees of freedom. All robots are placed on a single platform around the sample forming a nano-workbench (NWB. Each robot can travel the entire platform and has a minimum position resolution of 5 nm both in-plane and out-of-plane. The cantilever chip was glued to the robotic arm. Dispensing was done by the capillarity between the substrate and the cantilever tip, and was monitored visually through a microscope. To evaluate the performance of the NWB, we have performed three experiments: clamping of graphene with epoxy, mixing of femtolitre volume droplets to synthesize gold nanoparticles and accurately dispense electrolyte liquid for a nanobattery.

  14. Dynamic characterization of small fibers based on the flexural vibrations of a piezoelectric cantilever probe

    Science.gov (United States)

    Zhang, Xiaofei; Ye, Xuan; Li, Xide

    2016-08-01

    In this paper, we present a cantilever-probe system excited by a piezoelectric actuator, and use it to measure the dynamic mechanical properties of a micro- and nanoscale fiber. Coupling the fiber to the free end of the cantilever probe, we found the dynamic stiffness and damping coefficient of the fiber from the resonance frequency and the quality factor of the fiber-cantilever-probe system. The properties of Bacillus subtilis fibers measured using our proposed system agreed with tensile measurements, validating our method. Our measurements show that the piezoelectric actuator coupled to cantilever probe can be made equivalent to a clamped cantilever with an effective length, and calculated results show that the errors of measured natural frequency of the system can be ignored if the coupled fiber has an inclination angle of alignment of less than 10°. A sensitivity analysis indicates that the first or second resonant mode is the sensitive mode to test the sample’s dynamic stiffness, while the damping property has different sensitivities for the first four modes. Our theoretical analysis demonstrates that the double-cantilever probe is also an effective sensitive structure that can be used to perform dynamic loading and characterize dynamic response. Our method has the advantage of using amplitude-frequency curves to obtain the dynamic mechanical properties without directly measuring displacements and forces as in tensile tests, and it also avoids the effects of the complex surface structure and deformation presenting in contact resonance method. Our method is effective for measuring the dynamic mechanical properties of fiber-like one-dimensional (1D) materials.

  15. Torsional Vibrations of a Cantilever with Lateral Friction in a Resonance Friction Microscope

    Institute of Scientific and Technical Information of China (English)

    CHEN Jian-Song; GE Yun; ZHANG Hui

    2012-01-01

    A model of fundamental torsional vibration of a cantilever with lateral friction is presented by using the harmonic balance method. The model demonstrates that the torsional vibration has close relations with the lateral friction threshold, the lateral contact stiffness and the torsional vibration amplitude of the cantilever. When the threshold is larger than a product of the stiffness and the vibration amplitude, the lateral friction is a linear force with the amplitude. If the lateral friction threshold is less than the product, the motions of the tip on the sample can be stick-slip or slip motions. The results are useful to optimize and to manipulate the fundamental flexural vibration of the piezo-cantilever, and give an insight into the tribological characterization of the interface in a resonance friction microscope.%A model of fundamental torsional vibration of a cantilever with lateral friction is presented by using the harmonic balance method.The model demonstrates that the torsional vibration has close relations with the lateral friction threshold,the lateral contact stiffness and the torsional vibration amplitude of the cantilever.When the threshold is larger than a product of the stiffness and the vibration amplitude,the lateral friction is a linear force with the amplitude.If the lateral friction threshold is less than the product,the motions of the tip on the sample can be stick-slip or slip motions.The results are useful to optimize and to manipulate the fundamental flexural vibration of the piezo-cantilever,and give an insight into the tribological characterization of the interface in a resonance friction microscope.

  16. Measurements on hydrophobic and hydrophilic surfaces using a porous gamma alumina nanoparticle aggregate mounted on Atomic Force Microscopy cantilevers

    NARCIS (Netherlands)

    Das, Theerthankar; Becker, Thomas; Nair, Balagopal N.

    2010-01-01

    Atomic Force Microscopy (AFM) measurements are extensively used for a detailed understanding of molecular and surface forces. In this study, we present a technique for measuring such forces, using an AFM cantilever attached with a porous gamma alumina nanoparticle aggregate. The modified cantilever

  17. Note: Determination of torsional spring constant of atomic force microscopy cantilevers: Combining normal spring constant and classical beam theory

    DEFF Research Database (Denmark)

    Álvarez-Asencio, R.; Thormann, Esben; Rutland, M.W.

    2013-01-01

    A technique has been developed for the calculation of torsional spring constants for AFM cantilevers based on the combination of the normal spring constant and plate/beam theory. It is easy to apply and allow the determination of torsional constants for stiff cantilevers where the thermal power...

  18. Integrated cantilever-based flow sensors with tunable sensitivity for in-line monitoring of flow fluctuations in microfluidic systems

    DEFF Research Database (Denmark)

    Noeth, Nadine-Nicole; Keller, Stephan Sylvest; Boisen, Anja

    2014-01-01

    For devices such as bio-/chemical sensors in microfluidic systems, flow fluctuations result in noise in the sensor output. Here, we demonstrate in-line monitoring of flow fluctuations with a cantilever-like sensor integrated in a microfluidic channel. The cantilevers are fabricated in different m...... pumps connected to the microfluidic system. © 2013 by the authors; licensee MDPI, Basel, Switzerland....

  19. Three-dimensional finite element analysis of anterior two-unit cantilever resin-bonded fixed dental prostheses

    NARCIS (Netherlands)

    Keulemans, F.; Shinya, A.; Lassila, L.V.J.; Vallittu, P.K.; Kleverlaan, C.J.; Feilzer, A.J.; De Moor, R.J.G.

    2015-01-01

    The aim of this study was to evaluate the influence of different framework materials on biomechanical behaviour of anterior two-unit cantilever resin-bonded fixed dental prostheses (RBFDPs). A three-dimensional finite element model of a two-unit cantilever RBFDP replacing a maxillary lateral incisor

  20. 基于压电自感知执行器悬臂梁振动控制%Vibration control of cantilever beam using self-sensing actuator

    Institute of Scientific and Technical Information of China (English)

    董维杰; 孙宝元; 崔玉国; 杨志欣

    2001-01-01

    用一片压电陶瓷同时做传感器和执行器,基于应变速度电桥电路将应变速度信号从执行器控制电压中分离出来,制成了压电式自感知执行器;针对电桥不平衡情况,设计了由比例调节和相位滞后校正组成的简单控制器.悬臂梁振动控制实验证明:自感知执行器不仅能检测振动信息,而且能有效抑制悬臂梁的振动.%A single piezoelectric ceramic element simultaneously functionsas both a sensor and an actuator. A piezoelectric self-sensing actuator (SSA) is realized based on a strain rate bridge circuit that separates the strain rate signal from the control voltage. A simple controller consisting of a proportional and a phase lag compensation is designed in view of that the bridge is slightly unbalanced. Experimental results show that SSA can not only be a vibration detector but also has good performance in vibration control of a cantilever beam.

  1. Detecting the golgi protein 73 of liver cancer with micro cantilever

    Science.gov (United States)

    Thanh Tuyen Le, Thi; Pham, Van Tho; Nhat Khoa Phan, Thanh; Binh Pham, Van; Thao Le, Van; Hien Tong, Duy

    2014-12-01

    Golgi protein 73 (GP73) is a potential serum biomarker used in diagnosing human hepatocellular carcinoma (HCC). Compared to alpha-fetoprotein, detection of GP73 is expected to give better sensitivity and specificity and thus offers a better method for diagnosis of HCC at an early stage. In this paper, silicon nitride microcantilever was used to detect GP73. The cantilever was modified through many steps to contain antibody of GP73. The result shows that the cantilever can be used as a label-free sensor to detect this kind of biomarker.

  2. Comparative study on breaking wave forces on vertical walls with cantilever surfaces

    OpenAIRE

    Kisacik, D.; Bogaert, P; Troch, P.

    2010-01-01

    Physical experiments (at a scale of 1/20) are carried out using two different models: a vertical wall with cantilevering slab and a simple vertical wall. Tests are conducted for a range of values of water depth, wave period and wave height. The largest peak pressures were recorded at the SWL (82 pghs) on the vertical part and at the fixed corner of the cantilever slab (90 pghs). Pressure measurements and derived force calculations on the simple vertical wall were used to evaluate the existing...

  3. LCO flutter of cantilevered woven glass/epoxy laminate in subsonic flow

    Institute of Scientific and Technical Information of China (English)

    Dayang Laila Abang Haji Abdul Majid; ShahNor Basri

    2008-01-01

    The paper presents aeroelastic characteristics of a cantilevered composite wing,idealized as a composite flat plate laminate.The composite laminate was made from woven glass fibers with epoxy matrix.The elastic and dynamic properties of the laminate were determined experimentally for aeroelastic calculations.Aeroelastic wind tunnel testing of the laminate was performed and the result showed that flutter,a dynamic instability occurred.The cantilevered laminate also displayed limit cycle amplitude,post-flutter oscillation.The experimental flutter velocity and frequency were verified by our computational analysis.

  4. Vibrations of cantilevered circular cylindrical shells Shallow versus deep shell theory

    Science.gov (United States)

    Lee, J. K.; Leissa, A. W.; Wang, A. J.

    1983-01-01

    Free vibrations of cantilevered circular cylindrical shells having rectangular planforms are studied in this paper by means of the Ritz method. The deep shell theory of Novozhilov and Goldenveizer is used and compared with the usual shallow shell theory for a wide range of shell parameters. A thorough convergence study is presented along with comparisons to previously published finite element solutions and experimental results. Accurately computed frequency parameters and mode shapes for various shell configurations are presented. The present paper appears to be the first comprehensive study presenting rigorous comparisons between the two shell theories in dealing with free vibrations of cantilevered cylindrical shells.

  5. Designer cantilevers for even more accurate quantitative measurements of biological systems with multifrequency AFM

    Science.gov (United States)

    Contera, S.

    2016-04-01

    Multifrequency excitation/monitoring of cantilevers has made it possible both to achieve fast, relatively simple, nanometre-resolution quantitative mapping of mechanical of biological systems in solution using atomic force microscopy (AFM), and single molecule resolution detection by nanomechanical biosensors. A recent paper by Penedo et al [2015 Nanotechnology 26 485706] has made a significant contribution by developing simple methods to improve the signal to noise ratio in liquid environments, by selectively enhancing cantilever modes, which will lead to even more accurate quantitative measurements.

  6. In vacuo elastodynamics of a flexible cantilever for wideband energy harvesting

    Science.gov (United States)

    Tan, D.; Erturk, A.

    2016-04-01

    We explore the potential for bandwidth enhancement by merely exploiting the hardening nonlinearity of a flexible cantilever. To date, this cubic hardening behavior has been minor due to dissipative effects, especially fluid drag. The goal here is to minimize the fluid damping and thereby achieve the jump phenomenon. A vacuum setup that is compatible with the armature of a long-stroke shaker is employed. Experiments are conducted for a range of air pressure and base excitation levels. The overall nonlinear non-conservative elastodynamics of the cantilever is also modeled and experimentally validated by empirically accounting for fluid damping.

  7. Results of monitoring large carbon fiber post-tensioning systems in a balanced Cantilever Brdige (Dintelharbour Bridge, The Netherlands)

    NARCIS (Netherlands)

    Vervuurt, A.H.J.M.; Kaptijn, N.; Hageman, J.G.; Kuilboer, C.P.M.

    2012-01-01

    Steel post-tensioning systems and stay cables are susceptible to corrosion. Carbon fiber systems are not. However, there was no experience on the long term behavior of such post-tensioned elements. Four external tendons (75 m long), stressed to a load of 2650 kN, were applied in a large balanced can

  8. Integrated Cantilever-Based Flow Sensors with Tunable Sensitivity for In-Line Monitoring of Flow Fluctuations in Microfluidic Systems

    Directory of Open Access Journals (Sweden)

    Nadine Noeth

    2013-12-01

    Full Text Available For devices such as bio-/chemical sensors in microfluidic systems, flow fluctuations result in noise in the sensor output. Here, we demonstrate in-line monitoring of flow fluctuations with a cantilever-like sensor integrated in a microfluidic channel. The cantilevers are fabricated in different materials (SU-8 and SiN and with different thicknesses. The integration of arrays of holes with different hole size and number of holes allows the modification of device sensitivity, theoretical detection limit and measurement range. For an average flow in the microliter range, the cantilever deflection is directly proportional to the flow rate fluctuations in the microfluidic channel. The SiN cantilevers show a detection limit below 1 nL/min and the thinnest SU-8 cantilevers a detection limit below 5 nL/min. Finally, the sensor is applied for in-line monitoring of flow fluctuations generated by external pumps connected to the microfluidic system.

  9. Integrated cantilever-based flow sensors with tunable sensitivity for in-line monitoring of flow fluctuations in microfluidic systems.

    Science.gov (United States)

    Noeth, Nadine; Keller, Stephan Sylvest; Boisen, Anja

    2013-12-23

    For devices such as bio-/chemical sensors in microfluidic systems, flow fluctuations result in noise in the sensor output. Here, we demonstrate in-line monitoring of flow fluctuations with a cantilever-like sensor integrated in a microfluidic channel. The cantilevers are fabricated in different materials (SU-8 and SiN) and with different thicknesses. The integration of arrays of holes with different hole size and number of holes allows the modification of device sensitivity, theoretical detection limit and measurement range. For an average flow in the microliter range, the cantilever deflection is directly proportional to the flow rate fluctuations in the microfluidic channel. The SiN cantilevers show a detection limit below 1 nL/min and the thinnest SU-8 cantilevers a detection limit below 5 nL/min. Finally, the sensor is applied for in-line monitoring of flow fluctuations generated by external pumps connected to the microfluidic system.

  10. Effect of cantilever length and alloy framework on the stress distribution in peri-implant area of cantilevered implant-supported fixed partial dentures

    Directory of Open Access Journals (Sweden)

    Valdey SUEDAM

    2016-04-01

    Full Text Available ABSTRACT Because many mechanical variables are present in the oral cavity, the proper load transfer between the prosthesis and the bone is important for treatment planning and for the longevity of the implant-supported fixed partial denture. Objectives To verify the stress generated on the peri-implant area of cantilevered implant-supported fixed partial dentures and the potential effects of such variable. Material and Methods A U-shaped polyurethane model simulating the mandibular bone containing two implants (Ø 3.75 mm was used. Six groups were formed according to the alloy’s framework (CoCr or PdAg and the point of load application (5 mm, 10 mm and 15 mm of cantilever arm. A 300 N load was applied in pre-determined reference points. The tension generated on the mesial, lingual, distal and buccal sides of the peri-implant regions was assessed using strain gauges. Results Two-way ANOVA and Tukey statistical tests were applied showing significant differences (p<0.05 between the groups. Pearson correlation test (p<0.05 was applied showing positive correlations between the increase of the cantilever arm and the deformation of the peri-implant area. Conclusions This report demonstrated the CoCr alloy shows larger compression values compared to the PdAg alloy for the same distances of cantilever. The point of load application influences the deformation on the peri-implant area, increasing in accordance with the increase of the lever arm.

  11. Vibration based structural assessment of the rehabilitation intervention in r.c. segmental bridge

    Directory of Open Access Journals (Sweden)

    Franchetti Paolo

    2015-01-01

    Full Text Available A vibration based structural assessment campaign was carried out on a r.c. segmental bridge in North East Italy. The bridge has a cantilever static scheme, fixed at the top of the piers and with a hinge at the centre of the span. The particular configuration of the hinge consists in a couple of steel elements, each one composed by a tongue and groove joint. Since the year 1960, the hinge was subjected to consumption and degradation, that caused a malfunctioning of the device. An intervention of rehabilitation of the bridge led to a reinforcement of the existing hinges with the coupling of new metallic devices: new tongue and groove hinges were applied, that by one side allow the horizontal displacements and rotation, by the other side strongly reduce the relative vertical displacements of the two parts of the bridge. A dynamic test campaign was set up in order to assess the effectiveness of the intervention. The principal dynamic parameters were calculated and analysed with respect to the intervention that was realized. The tests clearly showed the effectiveness of the intervention, and helped the designer to have a better understanding of the structural behaviour of the bridge.

  12. The aesthetic composite bridge.

    Science.gov (United States)

    Feinman, R A

    1997-01-01

    New developments are constantly introduced in the search for the optimal treatment modality to restore a single anterior tooth. The patient attention has shifted to aesthetics of the restoration, biocompatibility of the dental materials utilized, conservative preparation of the teeth to be restored, and the retention of intact adjacent dentition. The learning objective of this article is to review the methods currently utilized and to present a recently introduced treatment modality--the two-component bridge, which combines the strength and resiliency of composite resin with the aesthetic advantages of porcelain. The technology of the material is reviewed, the predominantly lingual tooth preparation procedures are outlined, and the bridge try-in is described. The advantages of the two-component bridge are presented along with the contraindications and suggestions of careful case selection. Three cases with congenitally missing maxillary lateral incisors in youthful patients are presented to supplement the theoretical outline and to describe and illustrate the clinical procedure.

  13. Istanbul Bridge Conference 2014

    CERN Document Server

    Gülkan, Polat; Mahmoud, Khaled

    2016-01-01

      The book includes peer-reviewed contributions selected from presentations given at the Istanbul Bridge Conference 2014, held from August 11 – 13 in Istanbul, Turkey. It reports on the current challenges in bridge engineering faced by professionals around the globe, giving a special emphasis to recently developed techniques, innovations and opportunities. The book covers key topics in the field, including modeling and analysis methods; construction and erection techniques; design for extreme events and condition assessment and structural health monitoring. There is a balanced presentation of theory, research and practice. This book, which provides the readers with a comprehensive and timely reference guide on current practices in bridge engineering, is intended for professionals, academic researchers and students alike.

  14. Active Control of Suspension Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper some recent research on active control of very long suspension bridges, is presented. The presentation is based on research work at Aalborg University, Denmark. The active control system is based on movable flaps attached to the bridge girder. Wind load on bridges with or without...... flaps attached to the girder is briefly presented. A simple active control system is discussed. Results from wind tunnel experiments with a bridge section show that flaps can be used effectively to control bridge girder vibrations. Flutter conditions for suspension bridges with and without flaps...

  15. Investigation of cleaning and regeneration methods for reliable construction of DNA cantilever biosensors

    DEFF Research Database (Denmark)

    Quan, Xueling; Yi, Sun; Heiskanen, Arto

    to clean and regenerate the sensing surface of cantilever biosensors. Perchloric acid potential sweep, potassium hydroxide-hydrogen peroxide, and piranha cleaning are investigated here. Peak-current potential differences from cyclic voltammetry, X-ray photo-electron spectroscopy and fluorescence detection...

  16. An analytic model for accurate spring constant calibration of rectangular atomic force microscope cantilevers.

    Science.gov (United States)

    Li, Rui; Ye, Hongfei; Zhang, Weisheng; Ma, Guojun; Su, Yewang

    2015-10-29

    Spring constant calibration of the atomic force microscope (AFM) cantilever is of fundamental importance for quantifying the force between the AFM cantilever tip and the sample. The calibration within the framework of thin plate theory undoubtedly has a higher accuracy and broader scope than that within the well-established beam theory. However, thin plate theory-based accurate analytic determination of the constant has been perceived as an extremely difficult issue. In this paper, we implement the thin plate theory-based analytic modeling for the static behavior of rectangular AFM cantilevers, which reveals that the three-dimensional effect and Poisson effect play important roles in accurate determination of the spring constants. A quantitative scaling law is found that the normalized spring constant depends only on the Poisson's ratio, normalized dimension and normalized load coordinate. Both the literature and our refined finite element model validate the present results. The developed model is expected to serve as the benchmark for accurate calibration of rectangular AFM cantilevers.

  17. A simulation of the performance of a self-tuning energy harvesting cantilever beam

    Science.gov (United States)

    Kaplan, J. L.; Bonello, P.; Alalwan, M.

    2016-09-01

    A vibration energy harvester is typically a cantilever beam made up of one or two layers of piezoelectric material that is clamped at one end to a vibrating host structure. The harvester is typically tuned to the frequency of the ambient vibration to ensure maximum power generation. One method to ensure that the system stays tuned in the presence of a varying frequency is to attach a mass to the cantilever and apply a control system to adjust its position along the cantilever according to the ambient frequency. This paper presents a simulation of the performance of such a system, based on a distributed parameter electromechanical model of the sliding-mass beam. A variety of control systems are used to adjust the position of the movable mass during operation and are compared for their efficacy in maintaining resonance over a varying excitation frequency. It was found that the resonance frequency of a bimorph cantilever VEH (Vibration Energy Harvester) could be successfully tuned over a wide frequency range. Moreover, it is also found that much of the voltage output reduction at higher frequencies could be compensated for by a separate control system used to adjust the capacitor load.

  18. Fiber-top cantilevers: a new sensor on the tip of a fiber

    NARCIS (Netherlands)

    Iannuzzi, D.; Deladi, S.; Elwenspoek, M.C.

    2006-01-01

    Micromachined cantilevers are the most elementary example of miniaturized sensors. A free-standing rectangular beam can often detect changes in the chemical, biological and physical properties of the surroundings with sensitivity comparable to much more complicated devices. It is therefore not surp

  19. Performance Improvisation of Cantilever-type Silicon Micro AccelerationSensors Using Stress Concentration Regions Technique

    Directory of Open Access Journals (Sweden)

    B.P. Joshi

    2007-05-01

    Full Text Available Acceleration sensors find applications in missile and competent munitions subsystems.Cantilever-type sensor's sensitivity and bandwidth are dependant on material properties of  thecantilever and structure of proof mass. It is always desired to design a sensor as sensitive aspossible but also maintaining higher bandwidth. In piezoresistive (cantilever-type accelerometers,various techniques were employed by designers to enhance their sensitivity and bandwidth.Most of these techniques are usually focused on shape and size of either cantilever or proofmass. This paper presents a concept of creating stress concentration regions (SCRs on thecantilever for enhancing its sensitivity. Five types of structures were simulated to study thebehaviour of piezoresistive sensors with SCRs implementation. Use of SCRs results in substantialincrease in the sensitivity, which is of the order of 1.85 times the nominal sensitivity. It was aimedat maximising sensor's performance factor, which is the product of sensor bandwidth andsensitivity. This study gives new dimension to the ways of improving performance of cantilever-type inertial piezoresistive sensor.

  20. Stress distribution in implant-supported prostheses using different connection systems and cantilever lengths: digital photoelasticity.

    Science.gov (United States)

    Goiato, Marcelo Coelho; Shibayama, Ricardo; Gennari Filho, Humberto; de Medeiros, Rodrigo Antonio; Pesqueira, Aldiéris Alves; dos Santos, Daniela Micheline; de Araújo, Cleudmar Amaral

    2016-01-01

    Photoelastic analysis was used to evaluate the biomechanical behaviour of implant-supported, double-screwed crowns with different connection systems and cantilever lengths. Three models were made in PL-2 photoelastic resin and divided into six groups, on the basis of the implant connection system (external hexagon [EH] or Morse taper [MT]), type of abutment (Mini Pilar [Neodent, Curitiba, Paraná, Brazil] or "UCLA") and number of crowns in the cantilever (one or two). The implant-prosthesis unit was placed in a circular polariscope. Occlusal surfaces of the crowns were subjected to 100-N loads in the axial and oblique (45°) directions in a universal testing machine (EMIC). Generated stresses were recorded and analysed qualitatively in a graphics program (Adobe Photoshop). Under axial loading, all of the groups had similar numbers of fringes, which were increased when the crowns were subjected to oblique loading. The highest number of fringes was found during oblique loading in the EH + Mini Pilar group. In conclusion, although the type of implant connection system did not have a direct influence on the stress distribution for axial loading, the cantilever length did have a direct influence on stress distribution. Models with two crowns in the cantilever showed more stress, with a greater concentration of force on the cervical part of the implant.

  1. Highly Sensitive Polymer-based Cantilever-sensors for DNA Detection

    DEFF Research Database (Denmark)

    Gomez, Montserrat; Nordström, Maria; Alvarez, M.

    2005-01-01

    We present a technology for the fabrication of cantilever arrays aimed to develop an integrated biosensor microsystem. The fabrication process is based on spin coating of the photosensitive polymer and near-ultraviolet exposure. Arrays of up to 33 microcantilevers are fabricated in the novel poly...

  2. Development and characterization of electrochemical cantilever sensor for bio/chemical sensing applications

    DEFF Research Database (Denmark)

    Quan, Xueling; Fischer, Lee MacKenzie; Boisen, Anja

    2011-01-01

    We report the improvements made to our previously developed electrochemical cantilever (EC) sensor, where nanoporous gold material is employed as working electrodes in microcantilever arrays, while combined counter-reference electrodes are integrated on the chip. For a surface stress change of 1m...

  3. Mass and position determination of attached particles on cantilever based mass sensors

    DEFF Research Database (Denmark)

    Dohn, Søren; Svendsen, Winnie Edith; Boisen, Anja;

    2007-01-01

    modes. This finding is verified experimentally using a microscale cantilever with and without an attached gold bead. The resonant frequencies of several bending modes are measured as a function of the bead position. The bead mass and position calculated from the measured resonant frequencies are in good...

  4. An Experimental Study of the Local Parameters of a Damaged Cantilever

    DEFF Research Database (Denmark)

    Rytter, A.; Brincker, Rune; Kirkegaard, Poul Henning

    of results from experimental tests with six hollow section steel cantilevers containing a fatigue crack introduced from a narrow laser cut slot. The modal parameters have been identified for different size and location of a crack. The modal parameters have been estimated by mean of frequency domain and time...

  5. An Experimental Study of the Modal Parameters of a Damaged Cantilever

    DEFF Research Database (Denmark)

    Rytter, A.; Brincker, Rune; Kirkegaard, Poul Henning

    of results from experimental tests with six hollow section steel cantilevers containing a fatigue crack introduced from a narrow laser cut slot. The modal parameters have been identified for different size and location of a crack. The modal parameters have been estimated by mean of frequency domain and time...

  6. Cantilever-based micro-particle filter with simultaneous single particle detection

    DEFF Research Database (Denmark)

    Noeth, Nadine-Nicole; Keller, Stephan Sylvest; Boisen, Anja

    2011-01-01

    Currently, separation of whole blood samples on lab-on-a-chip systems is achieved via filters followed by analysis of the filtered matter such as counting of blood cells. Here, a micro-chip based on cantilever technology is developed, which enables simultaneous filtration and counting of micro...

  7. Nano-Workbench: A Combined Hollow AFM Cantilever and Robotic Manipulator

    NARCIS (Netherlands)

    Pérez Garza, H.; Ghatkesar, M.K.; Basak, S.; Löthman, P.; Staufer, U.

    2015-01-01

    To manipulate liquid matter at the nanometer scale, we have developed a robotic assembly equipped with a hollow atomic force microscope (AFM) cantilever that can handle femtolitre volumes of liquid. The assembly consists of four independent robots, each sugar cube sized with four degrees of freedom.

  8. Analysis of resonance frequency and pull-in voltages of curled micro-bimorph cantilevers

    NARCIS (Netherlands)

    Abdulla, S.M.C.; Yagubizade, H.; Krijnen, G.J.M.

    2012-01-01

    A systematic study is presented on the modelling, fabrication and measurements of curled micro-bimorph cantilevers, which are composed of a dielectric beam with a metal electrode layer coated on top. The device, having stress-induced upward curvature in the electrical off-state, functions as a verti

  9. 16 CFR Figure 1 to Part 1512 - Bicycle Front Fork Cantilever Bending Test Rig

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Bicycle Front Fork Cantilever Bending Test Rig 1 Figure 1 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 1 Figure 1 to Part 1512—Bicycle...

  10. Position and mass determination of multiple particles using cantilever based mass sensors

    DEFF Research Database (Denmark)

    Dohn, Søren; Schmid, Silvan; Amiot, Fabien;

    2010-01-01

    of several added particles to the resonant frequencies of a cantilever, and an identification procedure valid for particles with different masses is proposed. The identification procedure is tested by calculating positions and mass of multiple microparticles with similar mass positioned on individual...

  11. Self-mixing interferometry in vertical-cavity surface-emitting lasers for nanomechanical cantilever sensing

    DEFF Research Database (Denmark)

    Larsson, David; Greve, Anders; Hvam, Jørn Märcher;

    2009-01-01

    We have experimentally investigated self-mixing interference produced by the feedback of light from a polymer micrometer-sized cantilever into a vertical-cavity surface-emitting laser for sensing applications. In particular we have investigated how the visibility of the optical output power and t...

  12. Insight into mechanics of AFM tip-based nanomachining: bending of cantilevers and machined grooves.

    Science.gov (United States)

    Al-Musawi, R S J; Brousseau, E B; Geng, Y; Borodich, F M

    2016-09-23

    Atomic force microscope (AFM) tip-based nanomachining is currently the object of intense research investigations. Values of the load applied to the tip at the free end of the AFM cantilever probe used for nanomachining are always large enough to induce plastic deformation on the specimen surface contrary to the small load values used for the conventional contact mode AFM imaging. This study describes an important phenomenon specific for AFM nanomachining in the forward direction: under certain processing conditions, the deformed shape of the cantilever probe may change from a convex to a concave orientation. The phenomenon can principally change the depth and width of grooves machined, e.g. the grooves machined on a single crystal copper specimen may increase by 50% on average following such a change in the deformed shape of the cantilever. It is argued that this phenomenon can take place even when the AFM-based tool is operated in the so-called force-controlled mode. The study involves the refined theoretical analysis of cantilever probe bending, the analysis of experimental signals monitored during the backward and forward AFM tip-based machining and the inspection of the topography of produced grooves.

  13. AFM based dielectric spectroscopy: extended frequency range through excitation of cantilever higher eigenmodes.

    Science.gov (United States)

    Miccio, Luis A; Kummali, Mohammed M; Schwartz, Gustavo A; Alegría, Ángel; Colmenero, Juan

    2014-11-01

    In the last years, a new AFM based dielectric spectroscopy approach has been developed for measuring the dielectric relaxation of materials at the nanoscale, the so called nanoDielectric Spectroscopy (nDS). In spite of the effort done so far, some experimental aspects of this technique remain still unclear. In particular, one of these aspects is the possibility of extending the experimental frequency range, to date limited at high frequencies by the resonance frequency of the AFM cantilever as a main factor. In order to overcome this limitation, the electrical excitation of cantilever higher eigenmodes for measuring the dielectric relaxation is here explored. Thus, in this work we present a detailed experimental analysis of the electrical excitation of the cantilever second eigenmode. Based on this analysis we show that the experimental frequency range of the AFM based dielectric spectroscopy can be extended by nearly two decades with a good signal-to-noise ratio. By using the combination of first and second cantilever eigenmodes we study dissipation processes on well known PVAc based polymeric samples. Both, relaxation spectra and images with molecular dynamics contrast were thus obtained over this broader frequency range.

  14. In vitro evaluation of failure loads of nonmetal cantilevered resin-bonded fixed dental prostheses

    NARCIS (Netherlands)

    van Dalen, A.; Feilzer, A.J.; Kleverlaan, C.J.

    2008-01-01

    Purpose: To evaluate in vitro the influence of fiber reinforcement on the failure loads of resin composite beams, simulating cantilevered two-unit resin-bonded fixed dental prostheses, and compare the results with similarly obtained failure loads of ZrO2 and CoCr beams of a comparable design. Materi

  15. Maximizing Output Power in a Cantilevered Piezoelectric Vibration Energy Harvester by Electrode Design

    Science.gov (United States)

    Du, Sijun; Jia, Yu; Seshia, Ashwin

    2015-12-01

    A resonant vibration energy harvester typically comprises of a clamped anchor and a vibrating shuttle with a proof mass. Piezoelectric materials are embedded in locations of high strain in order to transduce mechanical deformation into electric charge. Conventional design for piezoelectric vibration energy harvesters (PVEH) usually utilizes piezoelectric material and metal electrode layers covering the entire surface area of the cantilever with no consideration provided to examining the trade-off involved with respect to maximizing output power. This paper reports on the theory and experimental verification underpinning optimization of the active electrode area of a cantilevered PVEH in order to maximize output power. The analytical formulation utilizes Euler-Bernoulli beam theory to model the mechanical response of the cantilever. The expression for output power is reduced to a fifth order polynomial expression as a function of the electrode area. The maximum output power corresponds to the case when 44% area of the cantilever is covered by electrode metal. Experimental results are also provided to verify the theory.

  16. Temperature effects in Au piezoresistors integrated in SU-8 cantilever chips

    DEFF Research Database (Denmark)

    Johansson, Alicia; Hansen, Ole; Hales, Jan Harry;

    2006-01-01

    We present a cantilever-based biosensor chip made for the detection of biochemical molecules. The device is fabricated entirely in the photosensitive polymer SU-8 except for integrated piezoresistors made of Au. The integrated piezoresistors are used to monitor the surface stress changes due to b...

  17. Direct-write nanoscale printing of nanogranular tunnelling strain sensors for sub-micrometre cantilevers

    Science.gov (United States)

    Dukic, Maja; Winhold, Marcel; Schwalb, Christian H.; Adams, Jonathan D.; Stavrov, Vladimir; Huth, Michael; Fantner, Georg E.

    2016-01-01

    The sensitivity and detection speed of cantilever-based mechanical sensors increases drastically through size reduction. The need for such increased performance for high-speed nanocharacterization and bio-sensing, drives their sub-micrometre miniaturization in a variety of research fields. However, existing detection methods of the cantilever motion do not scale down easily, prohibiting further increase in the sensitivity and detection speed. Here we report a nanomechanical sensor readout based on electron co-tunnelling through a nanogranular metal. The sensors can be deposited with lateral dimensions down to tens of nm, allowing the readout of nanoscale cantilevers without constraints on their size, geometry or material. By modifying the inter-granular tunnel-coupling strength, the sensors' conductivity can be tuned by up to four orders of magnitude, to optimize their performance. We show that the nanoscale printed sensors are functional on 500 nm wide cantilevers and that their sensitivity is suited even for demanding applications such as atomic force microscopy. PMID:27666316

  18. SEMICONDUCTOR TECHNOLOGY Supercritical carbon dioxide process for releasing stuck cantilever beams

    Science.gov (United States)

    Yu, Hui; Chaoqun, Gao; Lei, Wang; Yupeng, Jing

    2010-10-01

    The multi-SCCO2 (supercritical carbon dioxide) release and dry process based on our specialized SCCO2 semiconductor process equipment is investigated and the releasing mechanism is discussed. The experiment results show that stuck cantilever beams were held up again under SCCO2 high pressure treatment and the repeatability of this process is nearly 100%.

  19. Direct-write nanoscale printing of nanogranular tunnelling strain sensors for sub-micrometre cantilevers

    Science.gov (United States)

    Dukic, Maja; Winhold, Marcel; Schwalb, Christian H.; Adams, Jonathan D.; Stavrov, Vladimir; Huth, Michael; Fantner, Georg E.

    2016-09-01

    The sensitivity and detection speed of cantilever-based mechanical sensors increases drastically through size reduction. The need for such increased performance for high-speed nanocharacterization and bio-sensing, drives their sub-micrometre miniaturization in a variety of research fields. However, existing detection methods of the cantilever motion do not scale down easily, prohibiting further increase in the sensitivity and detection speed. Here we report a nanomechanical sensor readout based on electron co-tunnelling through a nanogranular metal. The sensors can be deposited with lateral dimensions down to tens of nm, allowing the readout of nanoscale cantilevers without constraints on their size, geometry or material. By modifying the inter-granular tunnel-coupling strength, the sensors' conductivity can be tuned by up to four orders of magnitude, to optimize their performance. We show that the nanoscale printed sensors are functional on 500 nm wide cantilevers and that their sensitivity is suited even for demanding applications such as atomic force microscopy.

  20. Flexural Vibration Test of a Cantilever Beam with a Force Sensor: Fast Determination of Young's Modulus

    Science.gov (United States)

    Digilov, Rafael M.

    2008-01-01

    We describe a simple and very inexpensive undergraduate laboratory experiment for fast determination of Young's modulus at moderate temperatures with the aid of a force sensor. A strip-shaped specimen rigidly bolted to the force sensor forms a clamped-free cantilever beam. Placed in a furnace, it is subjected to free-bending vibrations followed by…

  1. BUILDING "BRIDGES" WITH QUALITY ASSURANCE

    Science.gov (United States)

    The papr describes how, rather than building "bridges" across centuries, quality assurance (QA) personnel have the opportunity to build bridges across technical disciplines, between public and private organizations, and between different QA groups. As reviewers and auditors of a...

  2. Existing Steel Railway Bridges Evaluation

    Science.gov (United States)

    Vičan, Josef; Gocál, Jozef; Odrobiňák, Jaroslav; Koteš, Peter

    2016-12-01

    The article describes general principles and basis of evaluation of existing railway bridges based on the concept of load-carrying capacity determination. Compared to the design of a new bridge, the modified reliability level for existing bridges evaluation should be considered due to implementation of the additional data related to bridge condition and behaviour obtained from regular inspections. Based on those data respecting the bridge remaining lifetime, a modification of partial safety factors for actions and materials could be respected in the bridge evaluation process. A great attention is also paid to the specific problems of determination of load-caring capacity of steel railway bridges in service. Recommendation for global analysis and methodology for existing steel bridge superstructure load-carrying capacity determination are described too.

  3. DOE Information Bridge

    CERN Document Server

    United States. Department of Energy. Office of Scientific and Technical Information

    DOE Information Bridge, a component of EnergyFiles, provides free, convenient, and quick access to full-text DOE research and development reports in physics, chemistry, materials, biology, environmental sciences, energy technologies, engineering, computer and information science, renewable energy, and other topics. This vast collection includes over 43,000 reports that have been received and processed by OSTI since January 1995.

  4. Bridging the Technological Gap.

    Science.gov (United States)

    Lazow, Robert; And Others

    The aim of "Bridging the Technological Gap" (BTG), a federally funded demonstration project, is to use microcomputer technology in the rehabilitation of the psychiatrically disabled. Through the use of a custom designed microcomputer software package, clients receive remediation in areas of specific cognitive and behavioral deficits. The project…

  5. Bridging a Cultural Gap

    Science.gov (United States)

    Leviatan, Talma

    2008-01-01

    There has been a broad wave of change in tertiary calculus courses in the past decade. However, the much-needed change in tertiary pre-calculus programmes--aimed at bridging the gap between high-school mathematics and tertiary mathematics--is happening at a far slower pace. Following a discussion on the nature of the gap and the objectives of a…

  6. Bridge over troubled water?

    DEFF Research Database (Denmark)

    Svendsen, Gunnar Lind Haase; Nannestad, Peter; Svendsen, Gert Tinggaard

    2008-01-01

    The problem of integrating non-Western immigrants into Western welfare states is the focus of this paper. To address this issue, we suggest a social capital approach in which we apply the conceptual pair of bridging social capital (BR), which connects an individual to the broader social structure...

  7. Building a Straw Bridge

    Science.gov (United States)

    Teaching Science, 2015

    2015-01-01

    This project is for a team of students (groups of two or three are ideal) to design and construct a model of a single-span bridge, using plastic drinking straws as the building material. All steps of the design, construction, testing and critiquing stages should be recorded by students in a journal. Students may like to include labelled diagrams,…

  8. Building Bridges to China.

    Science.gov (United States)

    Wasta, Stephanie; Scott, Margaret

    1998-01-01

    Describes a theme cycle called "Building Bridges to China" developed for third grade students that focuses on the similarities between the lives of children and families in China and the United States. Explains that the theme cycle addresses the National Geography Standards and three of the National Council for the Social Studies standards. (CMK)

  9. An experimentally validated bimorph cantilever model for piezoelectric energy harvesting from base excitations

    Science.gov (United States)

    Erturk, A.; Inman, D. J.

    2009-02-01

    Piezoelectric transduction has received great attention for vibration-to-electric energy conversion over the last five years. A typical piezoelectric energy harvester is a unimorph or a bimorph cantilever located on a vibrating host structure, to generate electrical energy from base excitations. Several authors have investigated modeling of cantilevered piezoelectric energy harvesters under base excitation. The existing mathematical modeling approaches range from elementary single-degree-of-freedom models to approximate distributed parameter solutions in the sense of Rayleigh-Ritz discretization as well as analytical solution attempts with certain simplifications. Recently, the authors have presented the closed-form analytical solution for a unimorph cantilever under base excitation based on the Euler-Bernoulli beam assumptions. In this paper, the analytical solution is applied to bimorph cantilever configurations with series and parallel connections of piezoceramic layers. The base excitation is assumed to be translation in the transverse direction with a superimposed small rotation. The closed-form steady state response expressions are obtained for harmonic excitations at arbitrary frequencies, which are then reduced to simple but accurate single-mode expressions for modal excitations. The electromechanical frequency response functions (FRFs) that relate the voltage output and vibration response to translational and rotational base accelerations are identified from the multi-mode and single-mode solutions. Experimental validation of the single-mode coupled voltage output and vibration response expressions is presented for a bimorph cantilever with a tip mass. It is observed that the closed-form single-mode FRFs obtained from the analytical solution can successfully predict the coupled system dynamics for a wide range of electrical load resistance. The performance of the bimorph device is analyzed extensively for the short circuit and open circuit resonance

  10. Chaotic motion and its control for nonlinear nonplanar oscillations of a parametrically excited cantilever beam

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Wei [College of Mechanical Engineering, Beijing University of Technology, Beijing 100022 (China)] e-mail: sandyzhang0@yahoo.com

    2005-11-01

    This paper presents an analysis of the chaotic motion and its control for the nonlinear nonplanar oscillations of a cantilever beam subjected to a harmonic axial excitation and transverse excitations at the free end. A new method of controlling chaotic motion for the nonlinear nonplanar oscillations of the cantilever beam, refereed as to the force control approach, is proposed for the first time. The governing nonlinear equations of nonplanar motion under combined parametric and external excitations are obtained. The Galerkin procedure is applied to the governing equation to obtain a two-degree-of-freedom nonlinear system under combined parametric and forcing excitations for the in-plane and out-of-plane modes. The work is focused on the case of 2:1 internal resonance, principal parametric resonance-1/2 subharmonic resonance for the in-plane mode and fundamental parametric resonance-primary resonance for the out-of-plane mode. The method of multiple scales is used to transform the parametrically and externally excited system to the averaged equations which have a constant perturbation force. Based on the averaged equations obtained here, numerical simulation is utilized to discover the periodic and chaotic motions for the nonlinear nonplanar oscillations of the cantilever beam. The numerical results indicate that the transverse excitation in the z direction at the free end can control the chaotic motion to a period n motion or a static state for the nonlinear nonplanar oscillations of the cantilever beam. The methodology of controlling chaotic motion by using the transverse excitation is proposed. The transverse excitation in the z direction at the free end may be thought about to be an open-loop control. For the problem investigated in this paper, this approach is an effective methodology of controlling chaotic motion to a period n motion or a static state for the nonlinear nonplanar oscillations of the cantilever beam.

  11. Characterization of piesoelectric ZnO thin films and the fabrication of piezoelectric micro-cantilevers

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Raegan Lynn [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    In Atomic Force Microscopy (AFM), a microcantilever is raster scanned across the surface of a sample in order to obtain a topographical image of the sample's surface. In a traditional, optical AFM, the sample rests on a bulk piezoelectric tube and a control loop is used to control the tip-sample separation by actuating the piezo-tube. This method has several disadvantages--the most noticeable one being that response time of the piezo-tube is rather long which leads to slow imaging speeds. One possible solution aimed at improving the speed of imaging is to incorporate a thin piezoelectric film on top of the cantilever beam. This design not only improves the speed of imaging because the piezoelectric film replaces the piezo-tube as an actuator, but the film can also act as a sensor. In addition, the piezoelectric film can excite the cantilever beam near its resonance frequency. This project aims to fabricate piezoelectric microcantilevers for use in the AFM. Prior to fabricating the cantilevers and also part of this project, a systematic study was performed to examine the effects of deposition conditions on the quality of piezoelectric ZnO thin films deposited by RF sputtering. These results will be presented. The deposition parameters that produced the highest quality ZnO film were used in the fabrication of the piezoelectric cantilevers. Unfortunately, the fabricated cantilevers warped due to the intrinsic stress of the ZnO film and were therefore not usable in the AFM. The complete fabrication process will be detailed, the results will be discussed and reasons for the warping will be examined.

  12. ELASTIC-PLASTIC DYNAMIC RESPONSE OF A CANTILEVER BEAM SUBJECTED TO OBLIQUE IMPACT AT ITS TIP

    Institute of Scientific and Technical Information of China (English)

    Xi Feng; Liu Feng

    2005-01-01

    By employing large deformation governing equations expressed in the form of finite difference, the dynamic responses of an elastic, perfectly plastic cantilever subjected to an oblique impact at its tip was numerically studied. Through analyzing the instantaneous distribution of the yield function (ψ= |M/Mo|+ (N/No)2), bending moment and axial force during the early stage of the response, the elastic-plastic deformation mechanism and the influence of axial component of an oblique impact on the dynamic response of a cantilever beam were discussed. The present analysis shows that the deformation mechanism of an elastic-plastic cantilever subjected to an obtained by using the rigid, perfectly plastic approach, the mode of shrinking plastic region that occurred instantly after the oblique impact and the mode of stationary hinge were both confirmed.The primary features of the deformation mechanism are captured by both analysis methods. It has also been found that the beam's deformation is mainly controlled by the axial component of the oblique impact in the early phase of the dynamic response, the deformation mechanism is obviously different from the case of a transverse impact. With further development of the response,the axial component attenuates rapidly and gives negligible contribution to the yielding of the beam cross-section. At the same time, the bending moments along the cantilever develop gradually and dominate the beam's deformation. The numerical results indicate that the mass, impact speed and oblique angle are the important factors that influence the elastic-plastic dynamic response of a cantilever beam.

  13. Experimental Determination of Bending Resonances of Millimeter Size PVF2 Cantilevers

    Directory of Open Access Journals (Sweden)

    David F. Thompson

    2003-07-01

    Full Text Available The polymer piezoelectric polvinylidene fluoride has found widespread use in sensors and actuators. The bending mode of piezoelectricity offers very high sensitivities and low mechanical input impedance, but has not been studied in as much detail for sensor applications. We report the dynamic electromechanical properties of millimeter size cantilevers made from electroded films of PVF2. All devices tested had a single polymer layer. Several resonances are found below 1 kHz and the experimentally observed resonance frequency dependence on cantilever thickness and length are seen to agree well with published models which take the properties of the electrodes into account. It is found that bending resonances are also modulated by the width of the cantilever. Therefore, though the length and thickness control the resonance frequency most strongly, the actual realized value can be fine-tuned by changing cantilever width and the electrode material and its thickness. Further, all resonances display high piezoelectric coupling coefficients (keff, ranging between 0.2 - 0.35. The data presented here will be extremely useful in the design of sensors and actuators for a number of applications, since the combination of millimeter size scales and high piezoelectric sensitivities in the low audio range can be realized with this marriage of polymeric materials and cantilever geometries. Such an array of sensors can be used in cochlear implant applications, and when integrated with a resonance interrogation circuit can be used for the detection of low frequency vibrations of large structures. If appropriate mass/elasticity sensitive layers are coated on the electrodes, such a sensor can be used for the detection of a wide range of chemicals and biochemicals.

  14. The Bridges of Taishun County

    Institute of Scientific and Technical Information of China (English)

    MaJianhe

    2003-01-01

    The American film The Bridges of Madison County captured the imagination of many Chinese moviegoers with its bittersweet love story and scenes of rustic covered bridges. But the U.S. can't lay sole claim to such spectacular rural sights:China has its own county worldrenowned for unforgettable bridges.

  15. Revised Rules for Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Jensen, F. M.; Middleton, C.;

    This paper is based on research performed for the Highway Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: Concrete Bridges" It contains details of a methodology which can be used to generate Whole Life (WL) reliability profiles....... These WL reliability profiles may be used to establish revised rules for Concrete Bridges....

  16. Dynamic Bridge Response for a Bridge-friendly Truck

    Directory of Open Access Journals (Sweden)

    V. Šmilauer

    2004-01-01

    Full Text Available A truck with controlled semi-active suspensions traversing a bridge is examined for benefits to the bridge structure. The original concept of a road-friendly truck was extended to a bridge-friendly vehicle, using the same optimization tools. A half-car model with two independently driven axles is coupled with simply supported bridges (beam, slab model with the span range from 5 m to 50 m. Surface profile of the bridge deck is either stochastic or in the shape of a bump or a pot in the mid-span. Numerical integration in the MATLAB/SIMULINK environment solves coupled dynamic equations of motion with optimized truck suspensions. The rear axle generates the prevailing load and to a great extent determines the bridge response. A significant decrease in contact road-tire forces is observed and the mid-span bridge deflections are on average smaller, when compared to commercial passive suspensions. 

  17. Note: Determination of torsional spring constant of atomic force microscopy cantilevers: combining normal spring constant and classical beam theory.

    Science.gov (United States)

    Álvarez-Asencio, R; Thormann, E; Rutland, M W

    2013-09-01

    A technique has been developed for the calculation of torsional spring constants for AFM cantilevers based on the combination of the normal spring constant and plate/beam theory. It is easy to apply and allow the determination of torsional constants for stiff cantilevers where the thermal power spectrum is difficult to obtain due to the high resonance frequency and low signal/noise ratio. The applicability is shown to be general and this simple approach can thus be used to obtain torsional constants for any beam shaped cantilever.

  18. Electromechanical model of a resonating nano-cantilever-based sensor for high-resolution and high-sensitivity mass detection

    DEFF Research Database (Denmark)

    Abadal, G.; Davis, Zachary James; Helbo, Bjarne;

    2001-01-01

    A simple linear electromechanical model for an electrostatically driven resonating cantilever is derived. The model has been developed in order to determine dynamic quantities such as the capacitive current flowing through the cantilever-driver system at the resonance frequency, and it allows us...... to calculate static magnitudes such as position and voltage of collapse or the voltage versus deflection characteristic. The model is used to demonstrate the theoretical sensitivity on the attogram scale of a mass sensor based on a nanometre-scale cantilever, and to analyse the effect of an extra feedback loop...

  19. Simulation of multivariate diffusion bridges

    DEFF Research Database (Denmark)

    Bladt, Mogens; Finch, Samuel; Sørensen, Michael

    We propose simple methods for multivariate diffusion bridge simulation, which plays a fundamental role in simulation-based likelihood and Bayesian inference for stochastic differential equations. By a novel application of classical coupling methods, the new approach generalizes a previously...... proposed simulation method for one-dimensional bridges to the mulit-variate setting. First a method of simulating approzimate, but often very accurate, diffusion bridges is proposed. These approximate bridges are used as proposal for easily implementable MCMC algorithms that produce exact diffusion bridges...

  20. Bridging Classroom Language Ethnography

    OpenAIRE

    GRENFELL, MICHAEL JAMES

    2012-01-01

    PUBLISHED Paper #5: Bridging Classroom Language Ethnography, New Literacy Studies and Bourdieu?s Social Philosophy: Principles and Practice The purpose of this paper is to analyze and synthesize the various ways that classroom language ethnography, NLS, and Bourdieu?s social philosophy, were integrated. The goal of the analysis and synthesis is to provide a fresh perspective and fruitful insights on literacy in all its manifestations that provides the foundations for a more robust...

  1. Bridging as Coercive Accommodation

    CERN Document Server

    Bos, J W; Mineur, A M; Bos, Johan; Buitelaar, Paul; Mineur, Anne-Marie

    1995-01-01

    In this paper we discuss the notion of "bridging" in Discourse Representation Theory as a tool to account for discourse referents that have only been established implicitly, through the lexical semantics of other referents. In doing so, we use ideas from Generative Lexicon theory, to introduce antecedents for anaphoric expressions that cannot be "linked" to a proper antecedent, but that do not need to be "accommodated" because they have some connection to the network of discourse referents that is already established.

  2. Analysis on construction monitoring of large cantilever pre-stressed concrete cap beam%大悬臂预应力混凝土盖梁的施工监测分析

    Institute of Scientific and Technical Information of China (English)

    郭锐

    2015-01-01

    Taking the large cantilever pre-stressed concrete cap beam construction of a viaduct as an example,from the structure modeling,pre-stressed steel beam system,stress monitoring and other aspects,introduced the construction monitoring technology of bridge structure engineer-ing,through the stress and displacement monitoring analysis of construction process,pointed out that the theory calculated value of large cantile-ver cap beam model in line with construction measured value.%以某高架桥大悬臂预应力混凝土盖梁施工为例,从结构建模、预应力钢束体系、应力监测等方面,介绍了桥梁结构工程的施工监测技术,通过对施工过程中应力和位移的监测分析,指出大悬臂盖梁模型的理论计算值与施工实测值比较吻合。

  3. Sensitivity analysis of rectangular atomic force microscope cantilevers immersed in liquids based on the modified couple stress theory.

    Science.gov (United States)

    Lee, Haw-Long; Chang, Win-Jin

    2016-01-01

    The modified couple stress theory is adopted to study the sensitivity of a rectangular atomic force microscope (AFM) cantilever immersed in acetone, water, carbon tetrachloride (CCl4), and 1-butanol. The theory contains a material length scale parameter and considers the size effect in the analysis. However, this parameter is difficult to obtain via experimental measurements. In this study, a conjugate gradient method for the parameter estimation of the frequency equation is presented. The optimal method provides a quantitative approach for estimating the material length scale parameter based on the modified couple stress theory. The results show that the material length scale parameter of the AFM cantilever immersed in acetone, CCl4, water, and 1-butanol is 0, 25, 116.3, and 471 nm, respectively. In addition, the vibration sensitivities of the AFM cantilever immersed in these liquids are investigated. The results are useful for the design of AFM cantilevers immersed in liquids.

  4. Investigation of static and dynamic behavior of functionally graded piezoelectric actuated Poly-Si micro cantilever probe

    Science.gov (United States)

    Pandey, Vibhuti Bhushan; Parashar, Sandeep Kumar

    2016-04-01

    In the present paper a novel functionally graded piezoelectric (FGP) actuated Poly-Si micro cantilever probe is proposed for atomic force microscope. The shear piezoelectric coefficient d15 has much higher value than coupling coefficients d31 and d33, hence in the present work the micro cantilever beam actuated by d15 effect is utilized. The material properties are graded in the thickness direction of actuator by a simple power law. A three dimensional finite element analysis has been performed using COMSOL Multiphysics® (version 4.2) software. Tip deflection and free vibration analysis for the micro cantilever probe has been done. The results presented in the paper shall be useful in the design of micro cantilever probe and their subsequent utilization in atomic force microscopes.

  5. Enhanced quality factors and force sensitivity by attaching magnetic beads to cantilevers for atomic force microscopy in liquid

    CERN Document Server

    Hoof, Sebastian; Hoogenboom, Bart W

    2012-01-01

    Dynamic-mode atomic force microscopy (AFM) in liquid remains complicated due to the strong viscous damping of the cantilever resonance. Here we show that a high-quality resonance (Q>20) can be achieved in aqueous solution by attaching a microgram-bead at the end of the nanogram-cantilever. The resulting increase in cantilever mass causes the resonance frequency to drop significantly. However, the force sensitivity --- as expressed via the minimum detectable force gradient --- is hardly affected, because of the enhanced quality factor. Via the enhancement of the quality factor, the attached bead also reduces the relative importance of noise in the deflection detector. It can thus yield an improved signal-to-noise ratio when this detector noise is significant. We describe and analyze these effects for a set-up which includes magnetic actuation of the cantilevers and which can be easily implemented in any AFM system that is compatible with an inverted optical microscope.

  6. Design and analysis of a self-biased broadband magnetoelectric cantilever operated at multi-frequency windows

    Science.gov (United States)

    Ma, J. N.; Xin, C. Z.; Ma, J.; Lin, Y. H.; Nan, C. W.

    2017-03-01

    Magnetoelectric (ME) composites with self-biased and wide resonance frequency band properties are promising candidates for magnetic field sensor and energy harvester. Here, we present a ME cantilever by in-series connecting a few SrFe12O19/Metglas/Pb(Zr,Ti)O3 components. Due to the in-built magnetic bias of SrFe12O19, the ME cantilever shows self-biased property. Meanwhile, by merging the resonance responses of the in-series ME components together, the ME cantilever presents multi-wide resonance bands (i.e., 500 Hz ˜ 700 Hz, 3.3 kHz ˜ 4.4 kHz and 44 kHz ˜ 70 kHz). In these three wide frequency windows, the ME voltage coefficients (α V) of the ME cantilever are higher than 40 mV/Oe, 115 mV/Oe and 400 mV/Oe, respectively.

  7. Process nano scale mechanical properties measurement of thin metal films using a novel paddle cantilever test structure

    CERN Document Server

    Tong, Chi-Jia

    2008-01-01

    A new technique was developed for studying the mechanical behavior of nano-scale thin metal films on substrate is presented. The test structure was designed on a novel "paddle" cantilever beam specimens with dimensions as few hundred nanometers to less than 10 nanometers. This beam is in triangle shape in order to provide uniform plane strain distribution. Standard clean room processing was used to prepare the paddle sample. The experiment can be operated by using the electrostatic deflection on the paddle uniform distributed stress cantilever beam and then measure the deposited thin metal film materials on top of it. A capacitance technique was used to measurement on the other side of the deflected plate to measure its deflection with respect to the force. The measured strain was converted through the capacitance measurement for the deflection of the cantilever. System performance on the residual stress measurement of thin films are calculated with three different forces on the "paddle" cantilever beam, incl...

  8. SU-8 Cantilevers for Bio/chemical Sensing; Fabrication, Characterisation and Development of Novel Read-out Methods

    Directory of Open Access Journals (Sweden)

    Anja Boisen

    2008-03-01

    Full Text Available Here, we present the activities within our research group over the last five yearswith cantilevers fabricated in the polymer SU-8. We believe that SU-8 is an interestingpolymer for fabrication of cantilevers for bio/chemical sensing due to its simple processingand low Young’s modulus. We show examples of different integrated read-out methodsand their characterisation. We also show that SU-8 cantilevers have a reduced sensitivity tochanges in the environmental temperature and pH of the buffer solution. Moreover, weshow that the SU-8 cantilever surface can be functionalised directly with receptormolecules for analyte detection, thereby avoiding gold-thiol chemistry.

  9. Comparing AFM cantilever stiffness measured using the thermal vibration and the improved thermal vibration methods with that of an SI traceable method based on MEMS

    Science.gov (United States)

    Brand, Uwe; Gao, Sai; Engl, Wolfgang; Sulzbach, Thomas; Stahl, Stefan W.; Milles, Lukas F.; Nesterov, Vladimir; Li, Zhi

    2017-03-01

    PTB has developed a new contact based method for the traceable calibration of the normal stiffness of AFM cantilevers in the range from 0.03 N m‑1 to 300 N m‑1 to the SI units based on micro-electro-mechanical system (MEMS) actuators. This method is evaluated by comparing the measured cantilever stiffness with that measured by PTB’s new primary nanonewton force facility and by PTB’s microforce measuring device. The MEMS system was used to calibrate the stiffness of cantilevers in two case studies. One set of cantilevers for applications in biophysics was calibrated using the well-known thermal vibration method and the second set of cantilevers was calibrated by a cantilever manufacturer who applied an improved thermal vibration method based on calibrated reference cantilevers for the cantilever stiffness calibration. The comparison revealed a stiffness deviation of  +7.7% for the cantilevers calibrated using the thermal vibration method and a deviation of  +6.9% for the stiffnesses of the cantilevers calibrated using the improved thermal vibration method.

  10. Investigation of the Frequency Shift of a SAD Circuit Loop and the Internal Micro-Cantilever in a Gas Sensor

    Directory of Open Access Journals (Sweden)

    Zheng You

    2010-07-01

    Full Text Available Micro-cantilever sensors for mass detection using resonance frequency have attracted considerable attention over the last decade in the field of gas sensing. For such a sensing system, an oscillator circuit loop is conventionally used to actuate the micro-cantilever, and trace the frequency shifts. In this paper, gas experiments are introduced to investigate the mechanical resonance frequency shifts of the micro-cantilever within the circuit loop(mechanical resonance frequency, MRF and resonating frequency shifts of the electric signal in the oscillator circuit (system working frequency, SWF. A silicon beam with a piezoelectric zinc oxide layer is employed in the experiment, and a Self-Actuating-Detecting (SAD circuit loop is built to drive the micro-cantilever and to follow the frequency shifts. The differences between the two resonating frequencies and their shifts are discussed and analyzed, and a coefficientrelated to the two frequency shifts is confirmed.Micro-cantilever sensors for mass detection using resonance frequency have attracted considerable attention over the last decade in the field of gas sensing. For such a sensing system, an oscillator circuit loop is conventionally used to actuate the micro-cantilever, and trace the frequency shifts. In this paper, gas experiments are introduced to investigate the mechanical resonance frequency shifts of the micro-cantilever within the circuit loop(mechanical resonance frequency, MRF and resonating frequency shifts of the electric signal in the oscillator circuit (system working frequency, SWF. A silicon beam with a piezoelectric zinc oxide layer is employed in the experiment, and a Self-Actuating-Detecting (SAD circuit loop is built to drive the micro-cantilever and to follow the frequency shifts. The differences between the two resonating frequencies and their shifts are discussed and analyzed, and a coefficientrelated to the two frequency shifts is confirmed.

  11. The influence of refractive index change and initial bending of cantilevers on the optical lever readout method

    DEFF Research Database (Denmark)

    Dohn, Søren; Greve, Anders; Svendsen, Winnie Edith;

    2010-01-01

    It has been speculated that the initial bending of cantilevers has a major influence on the detector signal in a cantilever-based sensor using the optical lever readout method. We have investigated theoretically as well as experimentally the changes induced in the detector signal when the optical...... experimentally using an environmental chamber and varying the pressure. We sketch routes to circumvent the problem and formulas suitable for data treatment are given....

  12. Clustering mechanism of ethanol-water mixtures investigated with photothermal microfluidic cantilever deflection spectroscopy

    Science.gov (United States)

    Ghoraishi, M. S.; Hawk, J. E.; Phani, Arindam; Khan, M. F.; Thundat, T.

    2016-04-01

    The infrared-active (IR) vibrational mode of ethanol (EtOH) associated with the asymmetrical stretching of the C-C-O bond in pico-liter volumes of EtOH-water binary mixtures is calorimetrically measured using photothermal microfluidic cantilever deflection spectroscopy (PMCDS). IR absorption by the confined liquid results in wavelength dependent cantilever deflections, thus providing a complementary response to IR absorption revealing a complex dipole moment dependence on mixture concentration. Solvent-induced blue shifts of the C-C-O asymmetric vibrational stretch for both anti and gauche conformers of EtOH were precisely monitored for EtOH concentrations ranging from 20–100% w/w. Variations in IR absorption peak maxima show an inverse dependence on induced EtOH dipole moment (μ) and is attributed to the complex clustering mechanism of EtOH-water mixtures.

  13. Computational model for noncontact atomic force microscopy: energy dissipation of cantilever.

    Science.gov (United States)

    Senda, Yasuhiro; Blomqvist, Janne; Nieminen, Risto M

    2016-09-21

    We propose a computational model for noncontact atomic force microscopy (AFM) in which the atomic force between the cantilever tip and the surface is calculated using a molecular dynamics method, and the macroscopic motion of the cantilever is modeled by an oscillating spring. The movement of atoms in the tip and surface is connected with the oscillating spring using a recently developed coupling method. In this computational model, the oscillation energy is dissipated, as observed in AFM experiments. We attribute this dissipation to the hysteresis and nonconservative properties of the interatomic force that acts between the atoms in the tip and sample surface. The dissipation rate strongly depends on the parameters used in the computational model.

  14. High sensitivity resonance frequency measurements of individualmicro-cantilevers using fiber optical interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Duden, Thomas; Radmilovic, Velimir

    2009-03-04

    We describe a setup for the resonance frequency measurement of individual microcantilevers. The setup displays both high spatial selectivity and sensitivity to specimen vibrations by utilizing a tapered uncoated fiber tip. The high sensitivity to specimen vibrations is achieved by the combination of optical Fabry-Perot interferometry and narrow band RF detection. Wave fronts reflected on the specimen and on the fiber tip end face interfere, thus no reference plane on the specimen is needed, as demonstrated with the example of freestanding silicon nitride micro-cantilevers. The resulting system is integrated in a DB-235 dual beam FIB system, thereby allowing the measurement of micro-cantilever responses during observation in SEM mode. The FIB was used to modify the optical fiber tip. At this point of our RF system development, the microcantilevers used to characterize the detector were not modified in situ.

  15. Free Vibration Analysis for Dynamic Stiffness Degradation of Cracked Cantilever Plate

    Directory of Open Access Journals (Sweden)

    Oday. I. Abdullah

    2005-01-01

    Full Text Available In the present work a dynamic analysis technique have been developed to investigate and characterize the quantity of elastic module degradation of cracked cantilever plates due to presence of a defect such as surface of internal crack under free vibration. A new generalized technique represents the first step in developing a health monitoring system, the effects of such defects on the modal frequencies has been the main key quantifying the elasticity modulii due to presence any type of un-visible defect. In this paper the finite element method has been used to determine the free vibration characteristics for cracked cantilever plate (internal flaws, this present work achieved by different position of crack. Stiffness reduction in term of elastic material properties is analyzed through a parametric study of crack density factor. Results are given for Young’s modulus and shear modulus variation with respects the vibrational characteristics.

  16. Rapid detection of bacterial resistance to antibiotics using AFM cantilevers as nanomechanical sensors.

    Science.gov (United States)

    Longo, G; Alonso-Sarduy, L; Rio, L Marques; Bizzini, A; Trampuz, A; Notz, J; Dietler, G; Kasas, S

    2013-07-01

    The widespread misuse of drugs has increased the number of multiresistant bacteria, and this means that tools that can rapidly detect and characterize bacterial response to antibiotics are much needed in the management of infections. Various techniques, such as the resazurin-reduction assays, the mycobacterial growth indicator tube or polymerase chain reaction-based methods, have been used to investigate bacterial metabolism and its response to drugs. However, many are relatively expensive or unable to distinguish between living and dead bacteria. Here we show that the fluctuations of highly sensitive atomic force microscope cantilevers can be used to detect low concentrations of bacteria, characterize their metabolism and quantitatively screen (within minutes) their response to antibiotics. We applied this methodology to Escherichia coli and Staphylococcus aureus, showing that live bacteria produced larger cantilever fluctuations than bacteria exposed to antibiotics. Our preliminary experiments suggest that the fluctuation is associated with bacterial metabolism.

  17. MODELLING AND OPTIMISATION OF A BIMORPH PIEZOELECTRIC CANTILEVER BEAM IN AN ENERGY HARVESTING APPLICATION

    Directory of Open Access Journals (Sweden)

    CHUNG KET THEIN

    2016-02-01

    Full Text Available Piezoelectric materials are excellent transducers in converting vibrational energy into electrical energy, and vibration-based piezoelectric generators are seen as an enabling technology for wireless sensor networks, especially in selfpowered devices. This paper proposes an alternative method for predicting the power output of a bimorph cantilever beam using a finite element method for both static and dynamic frequency analyses. Experiments are performed to validate the model and the simulation results. In addition, a novel approach is presented for optimising the structure of the bimorph cantilever beam, by which the power output is maximised and the structural volume is minimised simultaneously. Finally, the results of the optimised design are presented and compared with other designs.

  18. Analysis of electromechanical parameters of electrostatic microrelay with a movable elastic cantilever electrode

    Science.gov (United States)

    Efremov, Georgy I.; Mukhurov, Nikolay I.; Galdetskiy, A. V.

    2000-04-01

    Literature provides a sufficient body of information on developments of electrostatic micro relays (EMR) with movable electrode (ME) in the form of a spring cantilever beam. However, little attention has been given to obvious close relationship between required characteristics and the corresponding design solutions of EMR components, which hinders the development of relay constructions optimal for specific working conditions. This paper presents a method for determining values and interrelations of electric and mechanical parameters of EMR's promising for certain applications. Schematically, the EMR consists of a rigid dielectric substrate 1 having a salient part 2 covered with a deposited stationary thin-film electrode (SE) 3 and spring plate 4 upon which a cantilever ME 5 is placed in the area hanging over the salient pat. Contacts 6 of control circuit are located at the electrode ends.

  19. Approximations for Large Deflection of a Cantilever Beam under a Terminal Follower Force and Nonlinear Pendulum

    Directory of Open Access Journals (Sweden)

    H. Vázquez-Leal

    2013-01-01

    Full Text Available In theoretical mechanics field, solution methods for nonlinear differential equations are very important because many problems are modelled using such equations. In particular, large deflection of a cantilever beam under a terminal follower force and nonlinear pendulum problem can be described by the same nonlinear differential equation. Therefore, in this work, we propose some approximate solutions for both problems using nonlinearities distribution homotopy perturbation method, homotopy perturbation method, and combinations with Laplace-Padé posttreatment. We will show the high accuracy of the proposed cantilever solutions, which are in good agreement with other reported solutions. Finally, for the pendulum case, the proposed approximation was useful to predict, accurately, the period for an angle up to 179.99999999∘ yielding a relative error of 0.01222747.

  20. Correction of Multiple Canine Impactions by Mixed Straightwire and Cantilever Mechanics: A Case Report

    Directory of Open Access Journals (Sweden)

    Sergio Paduano

    2014-01-01

    Full Text Available Background. This case report describes the orthodontic treatment of a woman, aged 17 years, with a permanent dentition, brachyfacial typology, Angle Class I, with full impaction of two canines (13,33, and a severe ectopy of the maxillary left canine. Her main compliant was the position of the ectopic teeth. Methods. Straightwire fixed appliances, together with cantilever mechanics, were used to correct the impaired occlusion and to obtain an ideal torque control. Results and Conclusion. The treatment objectives were achieved in 26 months of treatment. The impactions were fully corrected with an optimal torque. The cantilever mechanics succeeded in obtaining tooth repositioning in a short lapse of time. After treatment, the dental alignment was stable.

  1. Multi-resonant wideband energy harvester based on a folded asymmetric M-shaped cantilever

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Meng; Mao, Haiyang; Li, Zhigang; Liu, Ruiwen; Ming, Anjie [Key laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academic of Sciences, Beijing 100029 (China); Ou, Yi; Ou, Wen [Key laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academic of Sciences, Beijing 100029 (China); Smart Sensor Engineering Center, Jiangsu R& D Center for Internet of Things, Wuxi 214315 (China)

    2015-07-15

    This article reports a compact wideband piezoelectric vibration energy harvester consisting of three proof masses and an asymmetric M-shaped cantilever. The M-shaped beam comprises a main beam and two folded and dimension varied auxiliary beams interconnected through the proof mass at the end of the main cantilever. Such an arrangement constitutes a three degree-of-freedom vibrating body, which can tune the resonant frequencies of its first three orders close enough to obtain a utility wide bandwidth. The finite element simulation results and the experimental results are well matched. The operation bandwidth comprises three adjacent voltage peaks on account of the frequency interval shortening mechanism. The result shows that the proposed piezoelectric energy harvester could be efficient and adaptive in practical vibration circumstance based on multiple resonant modes.

  2. RBFNN Model for Predicting Nonlinear Response of Uniformly Loaded Paddle Cantilever

    Directory of Open Access Journals (Sweden)

    Abdullah H. Abdullah

    2009-01-01

    Full Text Available The Radial basis Function neural network (RBFNN model has been developed for the prediction of nonlinear response for paddle Cantilever with built-in edges and different sizes, thickness and uniform loads. Learning data was performed by using a nonlinear finite element program, incremental stages of the nonlinear finite element analysis were generated by using 25 schemes of built paddle Cantilevers with different thickness and uniform distributed loads. The neural network model has 5 input nodes representing the uniform distributed load and paddle size, length, width and thickness, eight nodes at hidden layer and one output node representing the max. deflection response (1500×1 represent the deflection response of load. Regression analysis between finite element results and values predicted by the neural network model shows the least error.

  3. Numerical analysis of dynamic force spectroscopy using the torsional harmonic cantilever

    Energy Technology Data Exchange (ETDEWEB)

    Solares, Santiago D [Department of Mechanical Engineering, University of Maryland, 2181 Glenn L. Martin Hall, College Park, MD 20742 (United States); Hoelscher, Hendrik, E-mail: ssolares@umd.edu [Karlsruhe Institute for Technology (KIT), Institute for Microstructure Technology (IMT), Hermann-von Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2010-02-19

    A spectral analysis method has been recently introduced by Stark et al (2002 Proc. Natl Acad. Sci. USA 99 8473-8) and implemented by Sahin et al (2007 Nat. Nanotechnol. 2 507-14) using a T-shaped cantilever design, the torsional harmonic cantilever (THC), which is capable of performing simultaneous tapping-mode atomic force microscopy imaging and force spectroscopy. Here we report on numerical simulations of the THC system using a simple dual-mass flexural-torsional model, which is applied in combination with Fourier data processing software to illustrate the spectroscopy process for quality factors corresponding to liquid, air and vacuum environments. We also illustrate the acquisition of enhanced topographical images and deformed surface contours under the application of uniform forces, and compare the results to those obtained with a previously reported linear dual-spring-mass model.

  4. Note: A high-performance, low-cost laser shutter using a piezoelectric cantilever actuator

    Science.gov (United States)

    Bowden, W.; Hill, I. R.; Baird, P. E. G.; Gill, P.

    2017-01-01

    We report the design and characterization of an optical shutter based on a piezoelectric cantilever. Compared to conventional electro-magnetic shutters, the device has intrinsically low power and is acoustically quiet. The cantilever position is controlled by a high-voltage op-amp circuit for easy tuning of the range of travel, and mechanical slew rate, which enables a factor of 30 reduction in mechanical noise compared to a rapidly switched device. We achieve shuttering rise and fall times of 11 μs, corresponding to mechanical slew rates of 1.3 ms-1, with a timing jitter of less than 1 μs. When used to create optical pulses, we achieve minimum pulse durations of 250 μs. The reliability of the shutter was investigated by operating continuously for one week at 10 Hz switching rate. After this period, neither the shutter delay or actuation speed had changed by a measurable amount.

  5. Increasing Energy-harvesting ability of piezoelectric unimorph cantilevers using Spring Supports

    Science.gov (United States)

    Kim, Kyung Bum; Nahm, San; Sung, Tae Hyun; Paik, Jong Hoo; Kim, Hyoung Jae

    2016-06-01

    We fabricated a spring-supported piezoelectric unimorph cantilever (SPUC) with enhanced energy-harvesting characteristics by using a 0.69Pb(Zr0.47Ti0.53)O3-0.31Pb(Ni0.6Zn0.4)1/3Nb2/3)O3 + CuO (0.5 mol%) thick film sintered at 950 °C; a spring having a spring constant of 14,320 N/m was used as the cantilever support. The SPUC could generate an output power as high as 29 mW with a spring constant of 14,320 N/m across a resistance of 150 kΩ; this corresponded to a power density of 34 mW/cm3. We, therefore, that the thus-fabricated SPUCs when supported by a spring can harvest increased levels of energy.

  6. Simultaneous Scanning Ion Conductance Microscopy and Atomic Force Microscopy with Microchanneled Cantilevers

    Science.gov (United States)

    Ossola, Dario; Dorwling-Carter, Livie; Dermutz, Harald; Behr, Pascal; Vörös, János; Zambelli, Tomaso

    2015-12-01

    We combined scanning ion conductance microscopy (SICM) and atomic force microscopy (AFM) into a single tool using AFM cantilevers with an embedded microchannel flowing into the nanosized aperture at the apex of the hollow pyramid. An electrode was positioned in the AFM fluidic circuit connected to a second electrode in the bath. We could thus simultaneously measure the ionic current and the cantilever bending (in optical beam deflection mode). First, we quantitatively compared the SICM and AFM contact points on the approach curves. Second, we estimated where the probe in SICM mode touches the sample during scanning on a calibration grid and applied the finding to image a network of neurites on a Petri dish. Finally, we assessed the feasibility of a double controller using both the ionic current and the deflection as input signals of the piezofeedback. The experimental data were rationalized in the framework of finite elements simulations.

  7. Measuring the resonant vibration of a sessile droplet using MEMS based cantilevers

    Science.gov (United States)

    Nguyen, Thanh-Vinh; Matsumoto, Kiyoshi; Shimoyama, Isao

    2015-11-01

    We directly measure the normal force distribution on the contact area during the 1st mode resonant vibration of a droplet using an array of MEMS based cantilever. The measurement result shows that the normal force change is the largest at the periphery of the contact area. The ratio between the amplitude of the normal force change at the periphery of the contact area over that at the center of the contact area was approximately 20 times, in the case of 1.8 μL water droplet whose equilibrium contact angle is 140 degrees. We also demonstrate a method to estimate viscosity based on the measurement of the droplet vibration using MEMS cantilevers. The proposed method is able to estimate viscosity using less than 3 μL sample and has a simple operating principle. We believe that this method is suitable for point-of-care testing and characterization of chemical and biological solutions.

  8. Fabrication of piezodriven, free-standing, all-oxide heteroepitaxial cantilevers on silicon

    Directory of Open Access Journals (Sweden)

    N. Banerjee

    2014-09-01

    Full Text Available We report on the fabrication and mechanical properties of all-oxide, free-standing, heteroepitaxial, piezoelectric, microelectromechanical systems (MEMS on silicon, using PbZr0.52Ti0.48O3 as the key functional material. The fabrication was enabled by the development of an epitaxial lift-off strategy for the patterning of multilayer oxide heterostructures grown on Si(001, employing a high temperature stable, sacrificial oxide template mask to obtain freestanding cantilever MEMS devices after substrate etching. All cantilevers, with lengths in the range 25–325 μm, width 50 μm, and total thickness of 300 nm, can be actuated by an external AC-bias. For lengths 50–125 μm, the second order bending mode formed the dominant resonance, whereas for the other lengths different or multiple modes were present.

  9. A virtual instrument to standardise the calibration of atomic force microscope cantilevers

    CERN Document Server

    Sader, John E; Gibson, Christopher T; Haviland, David B; Higgins, Michael J; Kilpatrick, Jason I; Lu, Jianing; Mulvaney, Paul; Shearer, Cameron J; Slattery, Ashley D; Thorén, Per-Anders; Tran, Jim; Zhang, Heyou; Zhang, Hongrui; Zheng, Tian

    2016-01-01

    Atomic force microscope (AFM) users often calibrate the spring constants of cantilevers using functionality built into individual instruments. This is performed without reference to a global standard, which hinders robust comparison of force measurements reported by different laboratories. In this article, we describe a virtual instrument (an internet-based initiative) whereby users from all laboratories can instantly and quantitatively compare their calibration measurements to those of others - standardising AFM force measurements - and simultaneously enabling non-invasive calibration of AFM cantilevers of any geometry. This global calibration initiative requires no additional instrumentation or data processing on the part of the user. It utilises a single website where users upload currently available data. A proof-of-principle demonstration of this initiative is presented using measured data from five independent laboratories across three countries, which also allows for an assessment of current calibratio...

  10. Theoretical & Experimental Studies on Vibration & Damping of Fibre-Reinforced Cantilever Laminates.

    Directory of Open Access Journals (Sweden)

    M. Ganapathi

    2000-07-01

    Full Text Available In this paper, vibration and damping analyses  of glass fibre-reinforced laminated composite cantilever beams and plates are studied using C1 finite element using shear deformation theory and alsothrough experiments. The formulation in the theoretical model includes in-plane and rotary inertiaterms. The governing equations for the complex eigenvalue problem based on complex elastic moduliare formulated. The solutions are obtained using QR algorithm. Parametric study is carried out tohighlight; the effects of lay-up and ply-angle of the laminates. A limited number of experimentalinvestigafions on cantilever laminates are conducted for obtaining the natural frequenciqs, dampingfactor and frequency responses. The comparison between the theoretical and the experimfntal resultsshows good agreement.

  11. An Euler-Bernoulli second strain gradient beam theory for cantilever sensors

    Science.gov (United States)

    Amiot, F.

    2013-04-01

    This paper derives an Euler-Bernoulli beam theory for isotropic elastic materials based on a second strain gradient description. As such a description has been proved to allow for the definition of surface tension for solids, the equations satisfied by a beam featuring a through-thickness cohesion modulus gradient are established in order to describe the behaviour of micro cantilever sensors. Closed-form solutions are given for mechanical and chemical loadings. It is then shown that the involved material parameters seem virtually identifiable from full-field measurements and that the shape of the displacement field resulting from a chemical loading depends on the cantilever's thickness as well as on the material parameters. This makes such a theory potentially able to explain some of the experimental results found in the literature.

  12. Experimental characterization of cantilever-type piezoelectric generator operating at resonance for vibration energy harvesting

    Science.gov (United States)

    Montanini, Roberto; Quattrocchi, Antonino

    2016-06-01

    A cantilever-type resonant piezoelectric generator (RPG) has been designed by gluing a PZT patch working in d31 mode onto a glass fibre reinforced composite cantilever beam with a discrete mass applied on its free end. The electrical and dynamic behaviour of the RPG prototype has been investigated by carrying out laboratory tests aimed to assess the effect of definite design parameters, specifically the electric resistance load and the excitation frequency. Results showed that an optimum resistance load exists, at which power generation is maximized. Moreover, it has been showed that power generation is strongly influenced by the vibration frequency highlighting that, at resonance, output power can be increased by more than one order of magnitude. Possible applications include inertial resonant harvester for energy recovery from vibrating machines, sea waves or wind flux and self-powering of wireless sensor nodes.

  13. Multi-resonant wideband energy harvester based on a folded asymmetric M-shaped cantilever

    Directory of Open Access Journals (Sweden)

    Meng Wu

    2015-07-01

    Full Text Available This article reports a compact wideband piezoelectric vibration energy harvester consisting of three proof masses and an asymmetric M-shaped cantilever. The M-shaped beam comprises a main beam and two folded and dimension varied auxiliary beams interconnected through the proof mass at the end of the main cantilever. Such an arrangement constitutes a three degree-of-freedom vibrating body, which can tune the resonant frequencies of its first three orders close enough to obtain a utility wide bandwidth. The finite element simulation results and the experimental results are well matched. The operation bandwidth comprises three adjacent voltage peaks on account of the frequency interval shortening mechanism. The result shows that the proposed piezoelectric energy harvester could be efficient and adaptive in practical vibration circumstance based on multiple resonant modes.

  14. Restoration of defects generated on the DAST crystal surface by scanning with AFM cantilever tip

    Energy Technology Data Exchange (ETDEWEB)

    Nanjo, Hiroshi; Komatsu, Kyoji; Suzuki, Toshishige M

    2004-10-01

    We have developed a simple method to restore the defects and holes generated on the (001) surface of 4-(4-Dimethylaminostyryl)-1-methylpyridinium tosylate (DAST) crystal by scanning the crystal with a cantilever tip of an atomic force microscope (AFM). The change in the surface morphology upon repeated scan process was followed by AFM observation at appropriate intervals. By adjustment of applied force on the cantilever, molecular-scale flatness on the crystal surface was restored. We proposed the following mechanism for the restoration: AFM tip carries the small fragment of DAST near step-edge and fills the holes or defects on the surface. After several times scanning of the AFM tip with the fragment, the defect-free surface was restored on the DAST crystal by filling the fragment in satisfying the ionic interaction around the holes.

  15. Harvested power and sensitivity analysis of vibrating shoe-mounted piezoelectric cantilevers

    Science.gov (United States)

    Moro, L.; Benasciutti, D.

    2010-11-01

    This paper presents a preliminary investigation on energy harvesting from human walking via piezoelectric vibrating cantilevers. Heel accelerations during human gait are established by correlating data gathered from the literature with direct experimental measurements. All the observed relevant features are synthesized in a typical (standard) acceleration signal, used in subsequent numerical simulations. The transient electromechanical response and the harvested power of a shoe-mounted bimorph cantilever excited by the standard acceleration signal is computed by numerical simulations and compared with measurements on a real prototype. A sensitivity analysis is finally developed to estimate the mean harvested power for a wide range of scavenger configurations. Acceptability criteria based on imposed geometrical constraints and resistance strength limits (e.g. fatigue limit) are also established. This analysis allows a quick preliminary screening of harvesting performance of different scavenger configurations.

  16. Segmentation of a Vibro-Shock Cantilever-Type Piezoelectric Energy Harvester Operating in Higher Transverse Vibration Modes

    Directory of Open Access Journals (Sweden)

    Darius Zizys

    2015-12-01

    Full Text Available The piezoelectric transduction mechanism is a common vibration-to-electric energy harvesting approach. Piezoelectric energy harvesters are typically mounted on a vibrating host structure, whereby alternating voltage output is generated by a dynamic strain field. A design target in this case is to match the natural frequency of the harvester to the ambient excitation frequency for the device to operate in resonance mode, thus significantly increasing vibration amplitudes and, as a result, energy output. Other fundamental vibration modes have strain nodes, where the dynamic strain field changes sign in the direction of the cantilever length. The paper reports on a dimensionless numerical transient analysis of a cantilever of a constant cross-section and an optimally-shaped cantilever with the objective to accurately predict the position of a strain node. Total effective strain produced by both cantilevers segmented at the strain node is calculated via transient analysis and compared to the strain output produced by the cantilevers segmented at strain nodes obtained from modal analysis, demonstrating a 7% increase in energy output. Theoretical results were experimentally verified by using open-circuit voltage values measured for the cantilevers segmented at optimal and suboptimal segmentation lines.

  17. Dynamically forced cantilever system: A piezo-polymer characterization tool with possible application for micromechanical HF resonator devices

    Science.gov (United States)

    Schwödiauer, Reinhard

    2005-04-01

    A cantilever system, driven to a dynamically forced oscillation by a small piezoelectric specimen is presented as a simple and accurate tool to determine the converse dynamic piezocoefficient up to several kHz. The piezoelectric sample is mounted on top of a reflective cantilever where it is free to oscillate without any mechanical constraint. A Nomarsky-interferometer detects the induced cantilever displacement. The presented technique is especially suited for a precise characterization of small and soft piezoelectric polymer-samples with rough surfaces. The capability of the dynamically forced cantilever principle is demonstrated with a LiNbO3 crystal and with a porous ferroelectretic polypropylene foam. Results from measurements between 400 Hz and 5 kHz were found to be in excellent agreement with published values. Additionally, the dynamically forced cantilever principle may possibly improve the sensitivity of some micromechanical cantilever-sensors and it could also be interesting for the design of enhanced micromechanical high frequency mixer filters. Some ideas about are briefly presented.

  18. Segmentation of a Vibro-Shock Cantilever-Type Piezoelectric Energy Harvester Operating in Higher Transverse Vibration Modes.

    Science.gov (United States)

    Zizys, Darius; Gaidys, Rimvydas; Dauksevicius, Rolanas; Ostasevicius, Vytautas; Daniulaitis, Vytautas

    2015-12-23

    The piezoelectric transduction mechanism is a common vibration-to-electric energy harvesting approach. Piezoelectric energy harvesters are typically mounted on a vibrating host structure, whereby alternating voltage output is generated by a dynamic strain field. A design target in this case is to match the natural frequency of the harvester to the ambient excitation frequency for the device to operate in resonance mode, thus significantly increasing vibration amplitudes and, as a result, energy output. Other fundamental vibration modes have strain nodes, where the dynamic strain field changes sign in the direction of the cantilever length. The paper reports on a dimensionless numerical transient analysis of a cantilever of a constant cross-section and an optimally-shaped cantilever with the objective to accurately predict the position of a strain node. Total effective strain produced by both cantilevers segmented at the strain node is calculated via transient analysis and compared to the strain output produced by the cantilevers segmented at strain nodes obtained from modal analysis, demonstrating a 7% increase in energy output. Theoretical results were experimentally verified by using open-circuit voltage values measured for the cantilevers segmented at optimal and suboptimal segmentation lines.

  19. Discussion of the Improved Methods for Analyzing a Cantilever Beam Carrying a Tip-Mass under Base Excitation

    Directory of Open Access Journals (Sweden)

    Wang Hongjin

    2014-01-01

    Full Text Available Two improved analytical methods of calculations for natural frequencies and mode shapes of a uniform cantilever beam carrying a tip-mass under base excitation are presented based on forced vibration theory and the method of separation of variables, respectively. The cantilever model is simplified in detail by replacing the tip-mass with an equivalent inertial force and inertial moment acting at the free end of the cantilever based on D’Alembert’s principle. The concentrated equivalent inertial force and inertial moment are further represented as distributed loads using Dirac Delta Function. In this case, some typical natural frequencies and mode shapes of the cantilever model are calculated by the improved and unimproved analytical methods. The comparing results show that, after improvement, these two methods are in extremely good agreement with each other even the offset distance between the gravity center of the tip-mass and the attachment point is large. As further verification, the transient and steady displacement responses of the cantilever system under a sine base excitation are presented in which two improved methods are separately utilized. Finally, an experimental cantilever system is fabricated and the theoretical displacement responses are validated by the experimental measurements successfully.

  20. Batch-fabrication of cantilevered magnets on attonewton-sensitivity mechanical oscillators for scanned-probe nanoscale magnetic resonance imaging.

    Science.gov (United States)

    Hickman, Steven A; Moore, Eric W; Lee, SangGap; Longenecker, Jonilyn G; Wright, Sarah J; Harrell, Lee E; Marohn, John A

    2010-12-28

    We have batch-fabricated cantilevers with ∼100 nm diameter nickel nanorod tips and force sensitivities of a few attonewtons at 4.2 K. The magnetic nanorods were engineered to overhang the leading edge of the cantilever, and consequently the cantilevers experience what we believe is the lowest surface noise ever achieved in a scanned probe experiment. Cantilever magnetometry indicated that the tips were well magnetized, with a ≤ 20 nm dead layer; the composition of the dead layer was studied by electron microscopy and electron energy loss spectroscopy. In what we believe is the first demonstration of scanned probe detection of electron-spin resonance from a batch-fabricated tip, the cantilevers were used to observe electron-spin resonance from nitroxide spin labels in a film via force-gradient-induced shifts in cantilever resonance frequency. The magnetic field dependence of the magnetic resonance signal suggests a nonuniform tip magnetization at an applied field near 0.6 T.

  1. Dynamic behaviour of dagger-shaped cantilevers for atomic force microscopy

    Science.gov (United States)

    Shen, Kangzhi; Hurley, Donna C.; Turner, Joseph A.

    2004-11-01

    Experimental techniques based on the atomic force microscope (AFM) have been developed for characterizing mechanical properties at the nanoscale and applied to a variety of materials and structures. Atomic force acoustic microscopy (AFAM) is one such technique that uses spectral information of the AFM cantilever as it vibrates in contact with a sample. In this paper, the dynamic behaviour of AFM cantilevers that have a dagger shape is investigated using a power-series method. Dagger-shaped cantilevers have plan-view geometry consisting of a rectangular section at the clamped end and a triangular section at the tip. Their geometry precludes modelling using closed-form expressions. The convergence of the series is demonstrated and the convergence radius is shown to be related to the given geometry. The accuracy and efficiency of the method are investigated by comparison with finite element results for several different cases. AFAM experiments are modelled by including a linear spring at the tip that represents the contact stiffness. The technique developed is shown to be very effective for inversion of experimental frequency information into contact stiffness results for AFAM. In addition, the sensitivities of the frequencies to the contact stiffness are discussed in terms of the various geometric parameters of the problem including the slope, the ratio of the rectangular to triangular lengths and the tip location. Calculations of contact stiffness from experimental data using this model are shown to be very good in comparison with other models. It is anticipated that this approach may be useful for other cantilever geometries as well, such that AFAM accuracy may be improved.

  2. Performance Analysis of Wind-Induced Piezoelectric Vibration Bimorph Cantilever for Rotating Machinery

    OpenAIRE

    Zhou, Gongbo; Wang, Houlian; Zhu, Zhencai; Huang, Linghua; Li, Wei

    2015-01-01

    Harvesting the energy contained in the running environment of rotating machinery would be a good way to supplement energy to the wireless sensor. In this paper, we take piezoelectric bimorph cantilever beam with parallel connection mode as energy collector and analyze the factors which can influence the generation performance. First, a modal response theory model is built. Second, the static analysis, modal analysis, and piezoelectric harmonic response analysis of the wind-induced piezoelectr...

  3. Actuating mechanism and design of a cylindrical traveling wave ultrasonic motor using cantilever type composite transducer.

    Directory of Open Access Journals (Sweden)

    Yingxiang Liu

    Full Text Available BACKGROUND: Ultrasonic motors (USM are based on the concept of driving the rotor by a mechanical vibration excited on the stator via piezoelectric effect. USM exhibit merits such as simple structure, quick response, quiet operation, self-locking when power off, nonelectromagnetic radiation and higher position accuracy. PRINCIPAL FINDINGS: A cylindrical type traveling wave ultrasonic motor using cantilever type composite transducer was proposed in this paper. There are two cantilevers on the outside surface of cylinder, four longitudinal PZT ceramics are set between the cantilevers, and four bending PZT ceramics are set on each outside surface of cantilevers. Two degenerate flexural vibration modes spatially and temporally orthogonal to each other in the cylinder are excited by the composite transducer. In this new design, a single transducer can excite a flexural traveling wave in the cylinder. Thus, elliptical motions are achieved on the teeth. The actuating mechanism of proposed motor was analyzed. The stator was designed with FEM. The two vibration modes of stator were degenerated. Transient analysis was developed to gain the vibration characteristic of stator, and results indicate the motion trajectories of nodes on the teeth are nearly ellipses. CONCLUSIONS: The study results verify the feasibility of the proposed design. The wave excited in the cylinder isn't an ideal traveling wave, and the vibration amplitudes are inconsistent. The distortion of traveling wave is generated by the deformation of bending vibration mode of cylinder, which is caused by the coupling effect between the cylinder and transducer. Analysis results also prove that the objective motions of nodes on the teeth are three-dimensional vibrations. But, the vibration in axial direction is minute compared with the vibrations in circumferential and radial direction. The results of this paper can guide the development of this new type of motor.

  4. Study on blister of the coating on solid cantilevers of hydraulic supports for coal mining

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this work, blister of the Cu-Sn plus Cr coating on solid cantilevers of hydraulic supports for coal mining was investigated by hydrogen-charging, Devanathan-Stachurski method and electrochemical impedance spectroscopy (EIS) measurement. It was found that the permeation hydrogen during the pickling process and the electroplating process was responsible for the blisters. The residual tensile stress due to the machining process would increase the permeation hydrogen amount during pickling and electroplating processes.

  5. Multi-material bio-fabrication of hydrogel cantilevers and actuators with stereolithography.

    Science.gov (United States)

    Chan, Vincent; Jeong, Jae Hyun; Bajaj, Piyush; Collens, Mitchell; Saif, Taher; Kong, Hyunjoon; Bashir, Rashid

    2012-01-01

    Cell-based biohybrid actuators are integrated systems that use biological components including proteins and cells to power material components by converting chemical energy to mechanical energy. The latest progress in cell-based biohybrid actuators has been limited to rigid materials, such as silicon and PDMS, ranging in elastic moduli on the order of mega (10(6)) to giga (10(9)) Pascals. Recent reports in the literature have established a correlation between substrate rigidity and its influence on the contractile behavior of cardiomyocytes (A. J. Engler, C. Carag-Krieger, C. P. Johnson, M. Raab, H. Y. Tang and D. W. Speicher, et al., J. Cell Sci., 2008, 121(Pt 22), 3794-3802, P. Bajaj, X. Tang, T. A. Saif and R. Bashir, J. Biomed. Mater. Res., Part A, 2010, 95(4), 1261-1269). This study explores the fabrication of a more compliant cantilever, similar to that of the native myocardium, with elasticity on the order of kilo (10(3)) Pascals. 3D stereolithographic technology, a layer-by-layer UV polymerizable rapid prototyping system, was used to rapidly fabricate multi-material cantilevers composed of poly(ethylene glycol) diacrylate (PEGDA) and acrylic-PEG-collagen (PC) mixtures. The incorporation of acrylic-PEG-collagen into PEGDA-based materials enhanced cell adhesion, spreading, and organization without altering the ability to vary the elastic modulus through the molecular weight of PEGDA. Cardiomyocytes derived from neonatal rats were seeded on the cantilevers, and the resulting stresses and contractile forces were calculated using finite element simulations validated with classical beam equations. These cantilevers can be used as a mechanical sensor to measure the contractile forces of cardiomyocyte cell sheets, and as an early prototype for the design of optimal cell-based biohybrid actuators.

  6. Feedback Control of Vibrations in a Micromachined Cantilever Beam with Electrostatic Actuators

    Science.gov (United States)

    Wang, P. K. C.

    1998-06-01

    The problem of feedback control of vibrations in a micromachined cantilever beam with nonlinear electrostatic actuators is considered. Various forms of nonlinear feedback controls depending on localized spatial averages of the beam velocity and displacement near the beam tip are derived by considering the time rate-of-change of the total energy of the beam. The physical implementation of the derived feedback controls is discussed briefly. The dynamic behaviour of the beam with the derived feedback controls is determined by computer simulation.

  7. Eigenvalues of an axially loaded cantilever beam with an eccentric end rigid body

    CERN Document Server

    Lajimi, S Amir Mousavi

    2014-01-01

    An analytical form of the characteristic equation for a vertically mounted cantilever beam with an end rigid body is obtained and solved for the eigenvalues of the structure. The effect of the weight of the structure is taken into consideration by estimating the load as a function of the length of the beam. The mass, rotary inertia and eccentricity of the end rigid body are demonstrated to considerably affect the eigenvalues of the structure.

  8. Vulnerability of bridges to fire

    DEFF Research Database (Denmark)

    Giuliani, Luisa; Crosti, C.; Gentili, F.

    2012-01-01

    Even if recent effort in developing methodology and measures for design structures against fire and explosions has been mostly focused on buildings, bridges can also be very sensitive to those actions, as witnesses by some recent bridge accidents, which caused major economic losses and also...... endangered people safety in few cases. Purpose of this paper is making a focus on the state of the art of the research and current regulations concerning the response of bridges to fire. Several cases of bridge fires are reported and a focus is made on the occurrence and consequence of bridge fires......, considering both the costs deriving by structural damages and by limited serviceability and other indirect societal aspects. Few cases of recent bridge fire are reviewed in detail and structural consequences are highlighted, distinguishing between damages directly induced by fire and damages induced by local...

  9. Coupled molecular and cantilever dynamics model for frequency-modulated atomic force microscopy.

    Science.gov (United States)

    Klocke, Michael; Wolf, Dietrich E

    2016-01-01

    A molecular dynamics model is presented, which adds harmonic potentials to the atomic interactions to mimic the elastic properties of an AFM cantilever. It gives new insight into the correlation between the experimentally monitored frequency shift and cantilever damping due to the interaction between tip atoms and scanned surface. Applying the model to ionic crystals with rock salt structure two damping mechanisms are investigated, which occur separately or simultaneously depending on the tip position. These mechanisms are adhesion hysteresis on the one hand and lateral excitations of the cantilever on the other. We find that the short range Lennard-Jones part of the atomic interaction alone is sufficient for changing the predominant mechanism. When the long range ionic interaction is switched off, the two damping mechanisms occur with a completely different pattern, which is explained by the energy landscape for the apex atom of the tip. In this case the adhesion hysteresis is always associated with a distinct lateral displacement of the tip. It is shown how this may lead to a systematic shift between the periodic patterns obtained from the frequency and from the damping signal, respectively.

  10. Nanomechanical modeling of a (100)[001] crack in a single crystal bcc iron cantilever beam

    Science.gov (United States)

    Skogsrud, Jørn; Jørum, Marie; Thaulow, Christian

    2017-02-01

    An atomistic model of a fully 3D, nano-sized, pre-cracked cantilever beam has been made and MD simulations have been performed to deflect the beam and initiate crack growth. The crucial process zone in front of the crack has been investigated with respect to linear elastic and elastic-plastic fracture mechanics and plastic deformation mechanisms such as dislocations and twinning. The effect of crack geometry and loading rate has been studied. Two crack geometries were compared, one atomically sharp and one blunted. The sharper crack was shown to lead to a cleaner crack extension on (110)-planes, while the rounded crack showed extension along the initial (100)-plane in accordance with experiments on micro-sized 3 wt% Si α-Fe cantilevers. The effect of strain rate was also investigated, and it was found that lower strain rate correlated better with experimental observations. However, the strain rate used is still several magnitudes higher than for experiments, limiting the usefulness of strain rate observations for predicting behavior in experiments. A brief post-deformation comparison between simulations and SEM-images of focused ion beam-fabricated micro-cantilevers was also done, showing possible signs of similar deformation mechanisms and dislocation systems between them.

  11. Peculiarities of the Third Natural Frequency Vibrations of a Cantilever for the Improvement of Energy Harvesting

    Directory of Open Access Journals (Sweden)

    Vytautas Ostasevicius

    2015-05-01

    Full Text Available This paper focuses on several aspects extending the dynamical efficiency of a cantilever beam vibrating in the third mode. A few ways of producing this mode stimulation, namely vibro-impact or forced excitation, as well as its application for energy harvesting devices are proposed. The paper presents numerical and experimental analyses of novel structural dynamics effects along with an optimal configuration of the cantilever beam. The peculiarities of a cantilever beam vibrating in the third mode are related to the significant increase of the level of deformations capable of extracting significant additional amounts of energy compared to the conventional harvester vibrating in the first mode. Two types of a piezoelectric vibrating energy harvester (PVEH prototype are analysed in this paper: the first one without electrode segmentation, while the second is segmented using electrode segmentation at the strain nodes of the third vibration mode to achieve effective operation at the third resonant frequency. The results of this research revealed that the voltage generated by any segment of the segmented PVEH prototype excited at the third resonant frequency demonstrated a 3.4–4.8-fold increase in comparison with the non-segmented prototype. Simultaneously, the efficiency of the energy harvester prototype also increased at lower resonant frequencies from 16% to 90%. The insights presented in the paper may serve for the development and fabrication of advanced piezoelectric energy harvesters which would be able to generate a considerably increased amount of electrical energy independently of the frequency of kinematical excitation.

  12. Optimization of Q-factor of AFM cantilevers using genetic algorithms.

    Science.gov (United States)

    Perez-Cruz, Angel; Dominguez-Gonzalez, Aurelio; Stiharu, Ion; Osornio-Rios, Roque A

    2012-04-01

    Micro cantilever beams have been intensively used in sensing applications including to scanning profiles and surfaces where there resolution and imaging speed are critical. Force resolution is related to the Q-factor. When the micro-cantilever operates in air with small separation gaps, the Q-factor is even more reduced due to the squeeze-film damping effect. Thus, the optimization of the configuration of an AFM micro-cantilever is presented in this work with the objective of improving its Q-factor. To accomplish this task, we propose the inclusion of holes as breathing chimneys in the initial design to reduce the squeeze-film damping effect. The evaluation of the Q-factor was carried out using finite element model, which is implemented to work together with the squeeze-film damping model. The methodology applied in the optimization process was genetic algorithms, which considers as constraints the maximum allowable stress, fundamental frequency and spring constant with respect to the initial design. The results show that the optimum design, which includes holes with an optimal location, increases the Q-factor almost five times compared to the initial design.

  13. Vortex-induced Vibration of a Flexible Free-hanging Circular Cantilever

    Directory of Open Access Journals (Sweden)

    R. W. Prastianto

    2009-11-01

    Full Text Available An experimental investigation on time-dependent motion of a flexible free-hanging circular cantilever subjected to uniform cross-flows has been carried out. The free-end condition cantilever has a 34.4 aspect ratio and a low mass ratio of about 1.24. The cylinder freely oscillates in both inline and transverse to the flow. Reynolds number varied from 10,800 to 37,800. The “jump phenomenon” was also found in the inline motion of the cylinder that agrees well with an existing comparable work, even occurred at lower flow velocity, Ur, due to distinct conditions of the test. At high flow velocities, the 3rd higher harmonic frequencies of the cylinder transverse response became predominant that produce quite different motion characteristics compared to the other existing comparable works with 2-dimensional bottom-end condition, even same in bidirectional motion aspect. Generally, the results suggested that the flexible free-hanging cantilever generate different vortex wake mode than either, a uniform (a short-rigid flexibly-mounted cylinder or a linear amplitude variation along the span case (a pivoted cylinder.

  14. Label-Free Glucose Detection Using Cantilever Sensor Technology Based on Gravimetric Detection Principles

    Directory of Open Access Journals (Sweden)

    Shuchen Hsieh

    2013-01-01

    Full Text Available Efficient maintenance of glucose homeostasis is a major challenge in diabetes therapy, where accurate and reliable glucose level detection is required. Though several methods are currently used, these suffer from impaired response and often unpredictable drift, making them unsuitable for long-term therapeutic practice. In this study, we demonstrate a method that uses a functionalized atomic force microscope (AFM cantilever as the sensor for reliable glucose detection with sufficient sensitivity and selectivity for clinical use. We first modified the AFM tip with aminopropylsilatrane (APS and then adsorbed glucose-specific lectin concanavalin A (Con A onto the surface. The Con A/APS-modified probes were then used to detect glucose by monitoring shifts in the cantilever resonance frequency. To confirm the molecule-specific interaction, AFM topographical images were acquired of identically treated silicon substrates which indicated a specific attachment for glucose-Con A and not for galactose-Con A. These results demonstrate that by monitoring the frequency shift of the AFM cantilever, this sensing system can detect the interaction between Con A and glucose, one of the biomolecule recognition processes, and may assist in the detection and mass quantification of glucose for clinical applications with very high sensitivity.

  15. A new approach to integrate PLZT thin films with micro-cantilevers

    Indian Academy of Sciences (India)

    Ravindra Singh; T C Goel; Sudhir Chandra

    2009-08-01

    In the present work, we report the preparation of PLZT thin films in pure perovskite phase by RF magnetron sputtering without external substrate heating and their integration with micro-cantilevers. The ‘lift-off’ process for patterning different layers of a micro-cantilever including PLZT, Pt/Ti and Au/Cr was employed. The basic requirement of lift-off process is that the deposition temperature should not exceed 200°C otherwise photoresist will burn out. Therefore, one of the aims of the present work was to prepare PLZT film at lower deposition temperatures, which can be subsequently annealed to form pure perovskite phase. This also strongly favours the incorporation of ‘lift-off’ process for patterning in the complete process flow. As no external substrate heating was required in the deposition of PLZT film, this objective has been successfully accomplished in the present work. The ‘lift-off’ process has been successfully adopted for patterning the composite layers of PLZT/Pt/Ti and Au/Cr using thick positive photo-resist (STR-1045). Different types of cantilever beams incorporating PLZT films have been successfully fabricated using ‘lift-off’ process and bulk micromachining technology. The proposed process can be advantageously applied for the fabrication of various MEMS devices.

  16. Theoretical and applied research on bistable dual-piezoelectric-cantilever vibration energy harvesting toward realistic ambience

    Science.gov (United States)

    Gao, Y.; Leng, Y.; Javey, A.; Tan, D.; Liu, J.; Fan, S.; Lai, Z.

    2016-11-01

    Pink noise, which is similar to realistic ambient noise, is normally used to simulate ambience where a piezoelectric energy harvesting system (PEHS) is set up. However, pink noise with standard spectral representation can only be used to simulate excitations assumed to possess constant intensity, whereas realistic ambient noise normally appears with a random spectrum and varying intensity in terms of different locations and time. The output performance of conventional bistable magnetic repulsive energy harvesters is significantly affected by the ambience intensity. Considering this fact, a model bistable dual-piezoelectric-cantilever energy harvester (DPEH) is developed in this study to achieve optimal broadband energy harvesting under a varying-intensity realistic circumstance. We utilized various realistic ambient conditions as excitations to obtain the DPEH energy harvesting performance for theoretical and applied study. The elastically supported PEHS has been proven to be more adaptive to realistic ambience with significant or medium intensity variation, but is less qualified for realistic ambience with constant intensity compared with the rigidly supported PEHS (RPEHS). Fortunately, the dual-piezoelectric-cantilever energy harvesting system is superior to the RPEHS under all circumstances because the dual-piezoelectric cantilevers are efficiently utilized for electromechanical energy conversion to realize optimal energy harvesting.

  17. Peculiarities of the third natural frequency vibrations of a cantilever for the improvement of energy harvesting.

    Science.gov (United States)

    Ostasevicius, Vytautas; Janusas, Giedrius; Milasauskaite, Ieva; Zilys, Mindaugas; Kizauskiene, Laura

    2015-05-28

    This paper focuses on several aspects extending the dynamical efficiency of a cantilever beam vibrating in the third mode. A few ways of producing this mode stimulation, namely vibro-impact or forced excitation, as well as its application for energy harvesting devices are proposed. The paper presents numerical and experimental analyses of novel structural dynamics effects along with an optimal configuration of the cantilever beam. The peculiarities of a cantilever beam vibrating in the third mode are related to the significant increase of the level of deformations capable of extracting significant additional amounts of energy compared to the conventional harvester vibrating in the first mode. Two types of a piezoelectric vibrating energy harvester (PVEH) prototype are analysed in this paper: the first one without electrode segmentation, while the second is segmented using electrode segmentation at the strain nodes of the third vibration mode to achieve effective operation at the third resonant frequency. The results of this research revealed that the voltage generated by any segment of the segmented PVEH prototype excited at the third resonant frequency demonstrated a 3.4-4.8-fold increase in comparison with the non-segmented prototype. Simultaneously, the efficiency of the energy harvester prototype also increased at lower resonant frequencies from 16% to 90%. The insights presented in the paper may serve for the development and fabrication of advanced piezoelectric energy harvesters which would be able to generate a considerably increased amount of electrical energy independently of the frequency of kinematical excitation.

  18. Label-free glucose detection using cantilever sensor technology based on gravimetric detection principles.

    Science.gov (United States)

    Hsieh, Shuchen; Hsieh, Shu-Ling; Hsieh, Chiung-Wen; Lin, Po-Chiao; Wu, Chun-Hsin

    2013-01-01

    Efficient maintenance of glucose homeostasis is a major challenge in diabetes therapy, where accurate and reliable glucose level detection is required. Though several methods are currently used, these suffer from impaired response and often unpredictable drift, making them unsuitable for long-term therapeutic practice. In this study, we demonstrate a method that uses a functionalized atomic force microscope (AFM) cantilever as the sensor for reliable glucose detection with sufficient sensitivity and selectivity for clinical use. We first modified the AFM tip with aminopropylsilatrane (APS) and then adsorbed glucose-specific lectin concanavalin A (Con A) onto the surface. The Con A/APS-modified probes were then used to detect glucose by monitoring shifts in the cantilever resonance frequency. To confirm the molecule-specific interaction, AFM topographical images were acquired of identically treated silicon substrates which indicated a specific attachment for glucose-Con A and not for galactose-Con A. These results demonstrate that by monitoring the frequency shift of the AFM cantilever, this sensing system can detect the interaction between Con A and glucose, one of the biomolecule recognition processes, and may assist in the detection and mass quantification of glucose for clinical applications with very high sensitivity.

  19. Microfluidic cantilever detects bacteria and measures their susceptibility to antibiotics in small confined volumes

    Science.gov (United States)

    Etayash, Hashem; Khan, M. F.; Kaur, Kamaljit; Thundat, Thomas

    2016-10-01

    In the fight against drug-resistant bacteria, accurate and high-throughput detection is essential. Here, a bimaterial microcantilever with an embedded microfluidic channel with internal surfaces chemically or physically functionalized with receptors selectively captures the bacteria passing through the channel. Bacterial adsorption inside the cantilever results in changes in the resonance frequency (mass) and cantilever deflection (adsorption stress). The excitation of trapped bacteria using infrared radiation (IR) causes the cantilever to deflect in proportion to the infrared absorption of the bacteria, providing a nanomechanical infrared spectrum for selective identification. We demonstrate the in situ detection and discrimination of Listeria monocytogenes at a concentration of single cell per μl. Trapped Escherichia coli in the microchannel shows a distinct nanomechanical response when exposed to antibiotics. This approach, which combines enrichment with three different modes of detection, can serve as a platform for the development of a portable, high-throughput device for use in the real-time detection of bacteria and their response to antibiotics.

  20. Coupled molecular and cantilever dynamics model for frequency-modulated atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Michael Klocke

    2016-05-01

    Full Text Available A molecular dynamics model is presented, which adds harmonic potentials to the atomic interactions to mimic the elastic properties of an AFM cantilever. It gives new insight into the correlation between the experimentally monitored frequency shift and cantilever damping due to the interaction between tip atoms and scanned surface. Applying the model to ionic crystals with rock salt structure two damping mechanisms are investigated, which occur separately or simultaneously depending on the tip position. These mechanisms are adhesion hysteresis on the one hand and lateral excitations of the cantilever on the other. We find that the short range Lennard-Jones part of the atomic interaction alone is sufficient for changing the predominant mechanism. When the long range ionic interaction is switched off, the two damping mechanisms occur with a completely different pattern, which is explained by the energy landscape for the apex atom of the tip. In this case the adhesion hysteresis is always associated with a distinct lateral displacement of the tip. It is shown how this may lead to a systematic shift between the periodic patterns obtained from the frequency and from the damping signal, respectively.

  1. Microfabricated photoplastic cantilever with integrated photoplastic/carbon based piezoresistive strain sensor

    DEFF Research Database (Denmark)

    Gammelgaard, Lauge; Rasmussen, Peter Andreas; Calleja, M.;

    2006-01-01

    We present an SU-8 micrometer sized cantilever strain sensor with an integrated piezoresistor made of a conductive composite of SU-8 polymer and carbon black particles. The composite has been developed using ultrasonic mixing. Cleanroom processing of the polymer composite has been investigated an...... silicon and the gauge factor of the composite material is relatively high, this polymer based strain sensor is more sensitive than a similar silicon based cantilever sensor. (c) 2006 American Institute of Physics.......We present an SU-8 micrometer sized cantilever strain sensor with an integrated piezoresistor made of a conductive composite of SU-8 polymer and carbon black particles. The composite has been developed using ultrasonic mixing. Cleanroom processing of the polymer composite has been investigated...... and it has been shown that it is possible to pattern the composite by standard UV photolithography. The composite material has been integrated into an SU-8 microcantilever and the polymer composite has been demonstrated to be piezoresistive with gauge factors around 15-20. Since SU-8 is much softer than...

  2. Morphological aspects of myocardial bridges.

    Science.gov (United States)

    Lujinović, Almira; Kulenović, Amela; Kapur, Eldan; Gojak, Refet

    2013-11-01

    Although some myocardial bridges can be asymptomatic, their presence often causes coronary disease either through direct compression of the "tunnel" segment or through stimulation and accelerated development of atherosclerosis in the segment proximally to the myocardial bridge. The studied material contained 30 human hearts received from the Department of Anatomy. The hearts were preserved 3 to 5 days in 10% formalin solution. Thereafter, the fatty tissue was removed and arterial blood vessels prepared by careful dissection with special reference to the presence of the myocardial bridges. Length and thickness of the bridges were measured by the precise electronic caliper. The angle between the myocardial bridge fibre axis and other axis of the crossed blood vessel was measured by a goniometer. The presence of the bridges was confirmed in 53.33% of the researched material, most frequently (43.33%) above the anterior interventricular branch. The mean length of the bridges was 14.64 ± 9.03 mm and the mean thickness was 1.23 ± 1.32 mm. Myocardial bridge fibres pass over the descending blood vessel at the angle of 10-90 degrees. The results obtained on a limited sample suggest that the muscular index of myocardial bridge is the highest for bridges located on RIA, but that the difference is not significant in relation to bridges located on other branches. The results obtained suggest that bridges located on other branches, not only those on RIA, could have a great contractive power and, consequently, a great compressive force, which would be exerted on the wall of a crossed blood vessel.

  3. Modular FRP Composite Bridge Deck

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    The bridge infrastructure of the United States is in constant need of repair and rehabilitation. It is reported that 43% of the bridges in the USA have been identified as being structurally deficient or functionally obsolete due to corrosion. SuperdeckTM, a non-corrosive fiber reinforced polymer (FRP) composite bridge deck. The Deck is designed and engineered into a lightweight, strong and rigid structure that will not corrode. The deck sections, composed of hexagon and double-trapezoid profi...

  4. Modelling railway bridge asset management

    OpenAIRE

    Le, Bryant Linh Hai

    2014-01-01

    The UK has a long history in the railway industry with a large number of railway assets. Railway bridges form one of the major asset groups with more than 35,000 bridges. The majority of the bridge population are old being constructed over 100 years ago. Many of the bridges were not designed to meet the current network demand. With an expected increasing rate of deterioration due to the increasing traffic loads and intensities, the management authorities are faced with the difficult task of k...

  5. Material Transport and Synthesis by Cantilever-free Scanning Probe Lithography

    Science.gov (United States)

    Liao, Xing

    Reliably synthesizing and transporting materials in nanoscale is the key question in many fields of nanotechnology. Cantilever-free scanning probe lithography, by replacing fragile and costly cantilevers with a robust and low cost elastomeric structure, fundamentally solved the low-throughput nature of scanning probe lithography, which has great potential to be a powerful and point-of-use tool for high throughput synthesis of various kinds of nanomaterials. Two nanolithographic methods, polymer pen lithography (PPL) and beam pen lithography (BPL), have been developed based on the cantilever-free architecture to directly deliver materials and transfer energy to substrates, respectively. The first portion of my thesis, including chapter two and chapter three, addresses major challenges remaining in the cantilever-free scanning probe lithographic techniques. Chapter two details the role of contact force in polymer pen lithography. A geometric model was developed to quantitatively explain the relationship between the z-piezo extension, the contact force and the resulted feature size. With such a model, force can be used as the in-situ feedback during the patterning and a new method for leveling the pen arrays was developed, which utilizes the total force between the pen arrays and the surface to achieve leveling with a tilt of less than 0.004°. In chapter three, massively multiplexed near-field photolithography has been demonstrated by combining BPL with a batch method to fabricate nanometer scale apertures in parallel fashion and a strategy to individually actuation of each pen in the pen array are discussed. This transformative combination enables one to writing arbitrary patterns composed of diffraction-unlimited features over square centimeter areas that are in registry with existing patterns and nanostructures, creating a unified tool for constructing and studying nanomaterials. The second portion of this thesis focuses on applications of cantilever-free scanning

  6. London Bridge Is Shaking Funny

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    Bridges generally don’t fall down without warning;they crack first. Searching for cracks is a tedious business,though, and bridge inspectors bave been known to miss them. Charles Farrar,a civil engineer at Los Alamos Na-

  7. Fatigue tests on aluminium bridges

    NARCIS (Netherlands)

    Maljaars, J.; Soetens, F.; Straalen, IJ.J. van

    2004-01-01

    Traffic bridges are subjected to variable loads and should therefore be checked on fatigue. Especially low weight materials, like aluminium, are sensitive to fatigue, because the variable load is a substantial part of the total load. This paper shows the structural design of an aluminium bridge load

  8. Fatigue tests on aluminium bridges

    NARCIS (Netherlands)

    Maljaars, J.; Soetens, F.; Straalen, IJ.J. van

    2005-01-01

    Traffic bridges are subjected to variable loads and should therefore be checked on fatigue. Especially low weight materials, like aluminium, are sensitive to fatigue, because the variable load is a substantial part of the total load. This paper shows the structural design of an aluminium bridge load

  9. Development of cooperative system bridges

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhe; WAN Qi-bai; SHI Lei

    2008-01-01

    Cooperative system bridges comprise several basic structures that act jointly to improve structural characteristics. We delved into the historical development of cooperative system bridges. Cooperative systems are classified as different-load cooperative systems and same-load cooperative systems by distinguishing the modes of load distribution. For different-load cooperation, individual basic structures are at different positions in the direction along bridge axis and carry the loads separately. While for same-load cooperation, all basic structures overlap in geometrical locations and support the entire loads conjointly. The choosing of span ratios between basic structures, the design of connections of different-load cooperative systems were discussed as well as optimizations of relative rigidity for same-load cooperative systems which greatly influence structural characteristics. The general situation and several structural measurements of several cooperative bridges were demonstrated. This information can assist engineers in developing their concepts in cooperative systems and can lead to more efficient and economical cooperative bridges.

  10. Linguistic Barriers and Bridges

    DEFF Research Database (Denmark)

    Thuesen, Frederik

    2016-01-01

    and intercultural communication, this article analyses interviews with 31 employees from two highly ethnically diverse Danish workplaces. The article shows how linguistic barriers such as different levels of majority language competence and their consequent misunderstandings breed mistrust and hostility, whilst......The influence of language on social capital in low-skill and ethnically diverse workplaces has thus far received very limited attention within the sociology of work. As the ethnically diverse workplace is an important social space for the construction of social relations bridging different social...... groups, the sociology of work needs to develop a better understanding of the way in which linguistic diversity influences the formation of social capital, i.e. resources such as the trust and reciprocity inherent in social relations in such workplaces. Drawing on theories about intergroup contact...

  11. Looking Beyond the Bridge

    DEFF Research Database (Denmark)

    Jahn, Elke; Rosholm, Michael

    We perform a comprehensive analysis of the stepping-stone effect of temporary agency employment on unemployed workers. Using the timing-of-events approach, we not only investigate whether agency employment is a bridge into regular employment but also analyze its effect on post-unemployment wages ...... is even more effective in tight labor markets, where firms use agency employment primarily to screen po-tential candidates for permanent posts. Finally, our results suggest that agency employment may improve subsequent match quality in terms of wages and job duration....... and job stability for unemployed Danish workers. We find evidence of large positive treatment effects, particularly for immigrants. There is also some indication that higher treatment intensity increases the likelihood of leav-ing unemployment for regular jobs. Our results show that agency employment...

  12. Structural Behavior of a Long-Span Partially Earth-Anchored Cable-Stayed Bridge during Installation of a Key Segment by Thermal Prestressing

    Directory of Open Access Journals (Sweden)

    Sang-Hyo Kim

    2016-08-01

    Full Text Available This study investigated structural behavior of long-span partially earth-anchored cable-stayed bridges with a main span length of 810 m that use a new key segment closing method based on a thermal prestressing technique. A detailed construction sequence analysis matched with the free cantilever method (FCM was performed using a three-dimensional finite element (FE model of a partially earth-anchored cable-stayed bridge. The new method offers an effective way of connecting key segments by avoiding large movements resulting from the removal of the longitudinal restraint owing to the asymmetry of axial forces in the girders near the pylons. The new method develops new member forces through the process of heating the cantilever system before installing the key segment and cooling the system continuously after installing key segments. The resulting forces developed by the thermal process enhance the structural behavior of partially earth-anchored cable-stayed bridges owing to decreased axial forces in the girders.

  13. Cascaded resonant bridge converters

    Science.gov (United States)

    Stuart, Thomas A. (Inventor)

    1989-01-01

    A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.

  14. Torsional instability in suspension bridges: The Tacoma Narrows Bridge case

    Science.gov (United States)

    Arioli, Gianni; Gazzola, Filippo

    2017-01-01

    All attempts of aeroelastic explanations for the torsional instability of suspension bridges have been somehow criticised and none of them is unanimously accepted by the scientific community. We suggest a new nonlinear model for a suspension bridge and we perform numerical experiments with the parameters corresponding to the collapsed Tacoma Narrows Bridge. We show that the thresholds of instability are in line with those observed the day of the collapse. Our analysis enables us to give a new explanation for the torsional instability, only based on the nonlinear behavior of the structure.

  15. 乌苏大桥主桥上部结构设计与计算%Design and Calculation of Superstructure of Main Bridge of Wusu Bridge

    Institute of Scientific and Technical Information of China (English)

    康晋; 肖海珠; 徐伟

    2011-01-01

    The main bridge of the Wusu Bridge is a single pylon and single cable plane cablestayed bridge with span arrangement (140+140) m and with a structural system of rigid fixity of the pylon, pier and girder. A summarized account of the design and calculation of the superstructure of the bridge is presented herewith. The main girder of the bridge is a composite girder with long cantilevers, the central part of the girder is designed as a two-cell and single-box steel girder and the steel cantilever at each side of the girder is the variable depth I-beam and is provided wiht a trough stringer at the far side, which are all topped with 25 cm thick concrete deck slabs connected with the girder via shearing studs. The part of the main girder close to the pylon is designed as a prestressed concrete box girder to facilitate the fixity of the girder with the pylon. The pylon is the single column pylon, 117 m in height. The stay cables, made up of low relaxation galvanized high strength parallel steel wire strands, are of the harp pattern cable plane arranged in the central alignment of the bridge deck. The finite element software MIDAS Civil 2006 and the SCDS programme are employed to calculate and analyze structure of the bridge. The results of the calculation and analysis indicate that the static, stability and dynamic characteristics of the bridge can meet the requirements in the relevant codes.%乌苏大桥主桥为独塔单索面斜拉桥,跨径布置为(140+140) m,采用塔、墩、梁固结体系,综述该桥上部结构设计与计算.主梁为带大挑臂的钢箱结合梁,中间钢箱梁采用单箱双室截面,两侧钢挑臂为变高度工字形梁,挑臂端部设槽形小纵梁;混凝土桥面板厚25 cm,与钢梁通过剪力钉连接;塔根部主梁采用预应力混凝土箱梁,以方便与桥塔固结;桥塔采用独柱式塔,高117 m;斜拉索为竖琴形中央平行索面布置,采用低松弛镀锌高强度平行钢丝束.采用有限元软件MIDAS Civil

  16. An energy harvester using piezoelectric cantilever beams undergoing coupled bending-torsion vibrations

    Science.gov (United States)

    Abdelkefi, A.; Najar, F.; Nayfeh, A. H.; Ben Ayed, S.

    2011-11-01

    Recently, piezoelectric cantilevered beams have received considerable attention for vibration-to-electric energy conversion. Generally, researchers have investigated a classical piezoelectric cantilever beam with or without a tip mass. In this paper, we propose the use of a unimorph cantilever beam undergoing bending-torsion vibrations as a new piezoelectric energy harvester. The proposed design consists of a single piezoelectric layer and a couple of asymmetric tip masses; the latter convert part of the base excitation force into a torsion moment. This structure can be tuned to be a broader band energy harvester by adjusting the first two global natural frequencies to be relatively close to each other. We develop a distributed-parameter model of the harvester by using the Euler-beam theory and Hamilton's principle, thereby obtaining the governing equations of motion and associated boundary conditions. Then, we calculate the exact eigenvalues and associated mode shapes and validate them with a finite element (FE) model. We use these mode shapes in a Galerkin procedure to develop a reduced-order model of the harvester, which we use in turn to obtain closed-form expressions for the displacement, twisting angle, voltage output, and harvested electrical power. These expressions are used to conduct a parametric study for the dynamics of the system to determine the appropriate set of geometric properties that maximizes the harvested electrical power. The results show that, as the asymmetry is increased, the harvester's performance improves. We found a 30% increase in the harvested power with this design compared to the case of beams undergoing bending only. We also show that the locations of the two masses can be chosen to bring the lowest two global natural frequencies closer to each other, thereby allowing the harvesting of electrical power from multi-frequency excitations.

  17. Nanomechanical assessment of human and murine collagen fibrils via atomic force microscopy cantilever-based nanoindentation.

    Science.gov (United States)

    Andriotis, Orestis G; Manuyakorn, Wiparat; Zekonyte, Jurgita; Katsamenis, Orestis L; Fabri, Sebastien; Howarth, Peter H; Davies, Donna E; Thurner, Philipp J

    2014-11-01

    The nanomechanical assessment of collagen fibrils via atomic force microscopy (AFM) is of increasing interest within the biomedical research community. In contrast to conventional nanoindentation there exists no common standard for conducting experiments and analysis of data. Currently used analysis approaches vary between studies and validation of quantitative results is usually not performed, which makes comparison of data from different studies difficult. Also there are no recommendations with regards to the maximum indentation depth that should not be exceeded to avoid substrate effects. Here we present a methodology and analysis approach for AFM cantilever-based nanoindentation experiments that allows efficient use of captured data and relying on a reference sample for determination of tip shape. Further we show experimental evidence that maximum indentation depth on collagen fibrils should be lower than 10-15% of the height of the fibril to avoid substrate effects and we show comparisons between our and other approaches used in previous works. While our analysis approach yields similar values for indentation modulus compared to the Oliver-Pharr method we found that Hertzian analysis yielded significantly lower values. Applying our approach we successfully and efficiently indented collagen fibrils from human bronchi, which were about 30 nm in size, considerably smaller compared to collagen fibrils obtained from murine tail-tendon. In addition, derived mechanical parameters of collagen fibrils are in agreement with data previously published. To establish a quantitative validation we compared indentation results from conventional and AFM cantilever-based nanoindentation on polymeric samples with known mechanical properties. Importantly we can show that our approach yields similar results when compared to conventional nanoindentation on polymer samples. Introducing an approach that is reliable, efficient and taking into account the AFM tip shape, we anticipate

  18. Damages Identification in the Cantilever-based on the Parameters of the Natural Oscillations

    Directory of Open Access Journals (Sweden)

    A. V. Cherpakov

    2016-01-01

    Full Text Available An approach to parametric identification of damages such as cracks in the rod cantilever construction is described. The identification method is based on analysis of shapes of the natural oscillations. The analytic modelling is performed in the Maple software on the base of the Euler-Bernoulli hypothesis. Crack is modelled by an elastic bending element. Transverse oscillations of the rod are considered. We take into account first four eigen modes of the oscillations. Parameters of amplitude, curvature and angle of bends of the waveforms are analysed. It was established that damage location is revealed by ‘kink’ on corresponding curves of the waveforms. The parameters of oscillation shapes are sensitive to the crack parameters in different degree. The novelty of the approach consists in that the identification procedure is divided into two stages: (a it is determined the crack location, and (b it is determined the crack size. Based on analytical modelling, an example of determination of dependence of the crack parameters on its size in the cantilever rod is presented. Study of features of the waveforms during identification of the fracture parameters shows that the features found in the form of ‘kinks’ and local extreme a of the angle between the tangent and curvature of waveforms for different modes of bending oscillations, define the crack location in cantilever. They can serve as one of diagnostic signs of crack identification and allow us to determine its location.Defence Science Journal, Vol. 66, No. 1, January 2016, pp. 44-50, DOI: http://dx.doi.org/10.14429/dsj.66.8182 

  19. Diameter-dependent dissipation of vibration energy of cantilevered multiwall carbon nanotubes.

    Science.gov (United States)

    Sawaya, Shintaro; Arie, Takayuki; Akita, Seiji

    2011-04-22

    This study investigated the mechanical properties of vibrating cantilevered multiwall carbon nanotubes in terms of energy loss in a vibrating nanotube. Young's moduli of the nanotubes show a clear dependence of the perfection of the sp(2) carbon network, as determined from Raman spectroscopy. The energy loss corresponding to the inverse of the quality factor increases with increasing tube diameter, although the nanotube maintains high mechanical strength around 0.5 TPa. This fact implies that the vibration energy is dissipated mainly not by defects, but by van der Waals interactions between walls.

  20. Cantilever anemometer based on a superconducting micro-resonator: application to superfluid turbulence.

    Science.gov (United States)

    Salort, J; Monfardini, A; Roche, P-E

    2012-12-01

    We present a new type of cryogenic local velocity probe that operates in liquid helium (1 K < T < 4.2 K) and achieves a spatial resolution of ≈ 0.1 mm. The operating principle is based on the deflection of a micro-machined silicon cantilever which reflects the local fluid velocity. Deflection is probed using a superconducting niobium micro-resonator sputtered on the sensor and used as a strain gauge. We present the working principle and the design of the probe, as well as calibration measurements and velocity spectra obtained in a turbulent helium flow above and below the superfluid transition.

  1. Application of a Cantilevered SWCNT with Mass at the Tip as a Nanomechanical Sensor

    DEFF Research Database (Denmark)

    Mehdipour, I.; Barari, Amin; Domairry, G.

    2011-01-01

    In this paper, the continuum mechanics method and a bending model is applied to obtain the resonant frequency of the fixed-free SWCNT where the mass is rigidly attached to the tip. This method used the Euler–Bernoulli theory with cantilevered boundary conditions where the effect of attached mass...... on resonant frequency, is added at the free end condition. The resonant frequencies of the fixed-free SWCNT have been investigated. The results showed the sensitivity of the single walled carbon nanotubes to different masses. Moreover, they indicate that by increasing the value of attached mass, the values...

  2. Screen printed PZT/PZT thick film bimorph MEMS cantilever device for vibration energy harvesting

    DEFF Research Database (Denmark)

    Xu, Ruichao; Lei, Anders; Christiansen, T.L.

    2011-01-01

    We present a MEMS-based PZT/PZT thick film bimorph vibration energy harvester with an integrated silicon proof mass. The most common piezoelectric energy harvesting devices utilize a cantilever beam of a non piezoelectric material as support beneath or in-between the piezoelectric material....... It provides mechanical support but it also reduces the power output. Our device replaces the support with another layer of the piezoelectric material, and with the absence of an inactive mechanical support all of the stresses induced by the vibrations will be harvested by the active piezoelectric elements....

  3. Analytical solution for functionally graded anisotropic cantilever beam under thermal and uniformly distributed load

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The bending problem of a functionally graded anisotropic cantilever beam subjected to thermal and uniformly distributed load is investigated, with material parameters being arbitrary functions of the thickness coordinate. The heat conduction problem is treated as a 1D problem through the thickness. Based on the elementary formulations for plane stress problem, the stress function is assumed to be in the form of polynomial of the longitudinal coordinate variable, from which the stresses can be derived.The stress function is then determined completely with the compatibility equation and boundary conditions. A practical example is presented to show the application of the method.

  4. Finite element vibration analysis of a partially covered cantilever beam with concentrated tip mass

    Energy Technology Data Exchange (ETDEWEB)

    Yaman, Mustafa [Department of Mechanical Engineering, Ataturk University, 25240 Erzurum (Turkey)]. E-mail: myaman@atauni.edu.tr

    2006-07-01

    The work presented in this paper is the theoretical investigation of the dynamical behavior of a cantilever beam, partially covered by damping and constraining layers, with concentrated mass at the free end. A finite element method is used in order to obtain the resonant frequencies and loss factors. The resonant frequencies and loss factors for different physical and geometrical parameters are determined. The variations of these two parameters are found to be strongly dependent on the geometrical and physical properties of the constraining layers and the mass ratio.

  5. Vibration Control of Cantilever Smart Beam by using Piezoelectric Actuators and Sensors

    Directory of Open Access Journals (Sweden)

    Dr. S. Mishra

    2010-08-01

    Full Text Available Vibration of a smart beam is being controlled. This smart beam setup is comprised of actuators and sensors placed at the root of a cantilever beam. Vibrations can be caused by various sources includinghuman activity and nearby motorized equipment. In this case, disturbance is produced using a white noise signal to the actuator. The piezoelectric sensors are used to detect the vibration. Simultaneously, feedback controller sends correction information to the actuator that minimizes the vibration. To optimize results, controllers were designed using Linear Quadratic Gaussian (LQGtheory. This theory generally results in high-order controllers. Additionally, optimal control theory is being used to directly optimize low-order controllers.

  6. Wind Pressure Characteristics at Windward Side of Long-Span Cantilevered Roof by Wind Tunnel Test

    Institute of Scientific and Technical Information of China (English)

    XIAN Rong; LIAO Hai-li; LI Ming-shui

    2009-01-01

    A rigid mode of long-span cantilevered roof was tested in wind tunnel.By analyzing the relation between wind angle and wind pressure coefficient and the relation between wind angle and wind shape factor,we found that 90° is the most disadvantageous wind angle.Furthermore,the fluctuation of wind pressure at the windward edge was reflected by power spectrum density (PSD) and coherence function.The correlation coefficients of measuring points on outer and inner surfaces verifys that the largest lift force was produced at 90°.

  7. Three-dimensional elastic analysis of a composite double cantilever beam specimen

    Science.gov (United States)

    Raju, I. S.; Shivakumar, K. N.; Crews, J. H., Jr.

    1988-01-01

    Attention is given to the stresses and the strain energy release rate along the delamination front in the present three-dimensional elastic analysis of a 24-ply, cocured double-cantilever beam specimen by means of 20-noded parabolic-isoparametric finite elements. At the free surface, the strain energy release rate was found to be substantially smaller than the plane strain value; this is suggested to be due to the free-surface effect that exists where the delamination meets the surface edge.

  8. Nano-Workbench: A Combined Hollow AFM Cantilever and Robotic Manipulator

    OpenAIRE

    Héctor Hugo Pérez Garza; Murali Krishna Ghatkesar; Shibabrata Basak; Per Löthman; Urs Staufer

    2015-01-01

    To manipulate liquid matter at the nanometer scale, we have developed a robotic assembly equipped with a hollow atomic force microscope (AFM) cantilever that can handle femtolitre volumes of liquid. The assembly consists of four independent robots, each sugar cube sized with four degrees of freedom. All robots are placed on a single platform around the sample forming a nano-workbench (NWB). Each robot can travel the entire platform and has a minimum position resolution of 5 nm both in-plane a...

  9. Compact FBG diaphragm accelerometer based on L-shaped rigid cantilever beam

    Institute of Scientific and Technical Information of China (English)

    Yinyan Weng; Xueguang Qiao; Zhongyao Feng; Manli Hu; Jinghua Zhang; YangYang

    2011-01-01

    A compact fiber Bragg grating (FBG) diaphragm accelerometer based on L-shaped rigid cantilever beam is proposed and experimentally demonstrated. The sensing system is based on the integration of a flat diaphragm and an L-shaped rigid cantilever beam. The FBG is pre-tensioned and the two side points are fixed, efficiently avoiding the unwanted chirp effect of grating. Dynamic vibration measurement shows that the proposed FBG diaphragm accelerometer provides a wide frequency response range (0-110 Hz) and an extremely high sensitivity (106.5 pm/g), indemnifying it as a good candidate for embedding structural health monitoring and seismic wave measurement.%A compact fiber Bragg grating (FBG) diaphragm accelerometer based on L-shaped rigid cantilever beam is proposed and experimentally demonstrated.The sensing system is based on the integration of a flat diaphragm and an L-shaped rigid cantilever beam.The FBG is pre-tensioned and the two side points are fixed,efficiently avoiding the unwanted chirp effect of grating.Dynamic vibration measurement shows that the proposed FBG diaphragm accelerometer provides a wide frequency response range (0-110 Hz) and an extremely high sensitivity (106.5 pm/g),indentifying it as a good candidate for embedding structural health monitoring and seismic wave measurement.In the past few decades,accelerometers based on fiber Bragg grating (FBG) have attracted a great deal of interest from researchers and engineers because they play a vital role in vibration measurements.In recent years,FBG accelerometers have been more and more applied in structural health monitoring[1-3) and seismic wave measurement[4-6].This study concerns about the development of geophones composed of FBG accelerometers in seismic exploration.The main frequency of geophones in seismic wave measurement of oil and gas exploration is usually below 100 Hz.An FBG-based accelerometer consisting of a mass resting on a layer of compliant material supported by a rigid base plate

  10. Analytical solution for functionally graded anisotropic cantilever beam subjected to linearly distributed load

    Institute of Scientific and Technical Information of China (English)

    HUANG De-jin; DING Hao-jiang; CHEN Wei-qiu

    2007-01-01

    The bending problem of a functionally graded anisotropic cantilever beam subjected to a linearly distributed load is investigated. The analysis is based on the exact elasticity equations for the plane stress problem. The stress function is introduced and assumed in the form of a polynomial of the longitudinal coordinate. The expressions for stress components are then educed from the stress function by simple differentiation.The stress function is determined from the compatibility equation as well as the boundary conditions by a skilful deduction. The analytical solution is compared with FEM calculation, indicating a good agreement.

  11. ACTIVE CONTROL OF A FLEXIBLE CANTILEVER PLATE WITH MULTIPLE TIME DELAYS

    Institute of Scientific and Technical Information of China (English)

    Longxiang Chen; Ji Pan; Guoping Cai

    2008-01-01

    Active control of a flexible cantilever plate with multiple time delays is investigated using the discrete optimal control method.A controller with multiple time delays is presented.In this controller,time delay effect is incorporated in the mathematical model of the dynamic system throughout the control design and no approximations and assumptions are made in the controller derivation,so the system stability is easily guaranteed.Furthermore,this controller is available for both small time delays and large time delays.The feasibility and efficiency of the proposed controller are verified through numerical simulations in the end of this paper.

  12. Damping control of a CFRP cantilevered beam with electrorheological fluids actuator

    Science.gov (United States)

    Fukuda, Takehito; Oshima, Nobuo

    1996-04-01

    Effects of waveform and frequency of electric fields applied to electro-rheological (ER) fluids are investigated on structural damping of a CFRP composite beam containing ER fluids. As the experimental results, the rectangular waveform is more effective for control of ER effects than the sinusoidal one. In vibration analysis, a simplified mass-spring-damper system is adopted to feature the first flexural mode of the cantilevered composite beam, where the damping factor is changed in time as a function of waveform which is applied to electric fields.

  13. Vibrations of twisted cantilevered plates - Summary of previous and current studies

    Science.gov (United States)

    Leissa, A. W.; Macbain, J. C.; Kielb, R. E.

    1984-01-01

    This work summarizes a comprehensive study made of the free vibrations of twisted, cantilevered plates of rectangular planform. Numerous theoretical and experimental investigations previously made by others have resulted in frequency results which disagree considerably. To clarify the problem a joint industry/government/university research effort was initiated to obtain comprehensive theoretical and experimental results for models having useful ranges of aspect ratios, thickness ratios and twist angles. Theoretical data came from 19 independent computer analyses, including finite element, shell theory and beam theory idealizations. Two independent sets of experimental data were also obtained. The theoretical and experimental results are summarized and compared.

  14. A versatile cantilever beam magnetometer for ex situ characterization of magnetic materials.

    Science.gov (United States)

    Adhikari, R; Sarkar, A; Das, A K

    2012-01-01

    We have designed, fabricated, and made operational an ex situ cantilever beam magnetometer (CBM), which is versatile in the sense that it can measure most of the magnetic properties of a material in all probable shapes. The working principle of a CBM is discussed considering the magnetic torque into the beam theory. The individual components of the instrument are described in details and experiments were performed on the bulk materials, pellets of nanoparticles, ribbon samples, and thin films, and the magnetization, magnetostriction, and magnetocrystalline anisotropy were studied. This magnetometer is inexpensive, but versatile and would be suitable for the research as well as teaching laboratories.

  15. Laser spot position dependent photothermal mode cooling of a micro-cantilever

    CERN Document Server

    Fu, Hao; Liu, Yong; Chu, Jiaru; Cao, Gengyu

    2011-01-01

    We explore the laser spot position (LSP) dependent photothermal mode cooling of a micro-cantilever in a Fabry-P\\'erot (FP) cavity. Depending on the LSP along the lever, photothermal coupling to the first two mechanical modes can be either parallel or anti-parallel. This LSP dependent behavior is analyzed theoretically by a simple model, which is in quantitatively agreement with our experimental observation. From simulation, the parallel and anti-parallel coupling region is identified along the lever. We conclude that a more efficient mode cooling may be achieved in the parallel coupling region.

  16. Effect of Surface Layer on Electromechanical Stability of Tweezers and Cantilevers Fabricated from Conductive Cylindrical Nanowires

    Science.gov (United States)

    Keivani, Maryam; Koochi, Ali; Sedighi, Hamid M.; Abadyan, Mohamadreza; Farrokhabadi, Amin; Shahedin, Abed Moheb

    2016-12-01

    Herein, the impact of surface layer on the stability of nanoscale tweezers and cantilevers fabricated from nanowires with cylindrical cross section is studied. A modified continuum based on the Gurtin-Murdoch surface elasticity is applied for incorporating the presence of surface layer. Considering the cylindrical geometry of the nanowire, the presence of the Coulomb attraction and dispersion forces are incorporated in the derived formulations. Three different approaches, i.e. numerical differential quadrature method (DQM), an approximated homotopy perturbation method (HPM) and developing lumped parameter model (LPM) have been employed to solve the governing equations. The impact of surface layer on the instability of the system is demonstrated.

  17. Characterization of Interlaminar Crack Growth in Composites with the Double Cantilever Beam Specimen

    Science.gov (United States)

    Hunston, D. L.

    1984-01-01

    A project to examine the double cantilever beam specimen as a quantitative test method to assess the resistance of various composite materials to interlaminar crack growth is discussed. A second objective is to investigate the micromechanics of failure for composites with tough matrix resins from certain generic types of polymeric systems: brittle thermosets, toughened thermosets, and thermoplastics. Emphasis is given to a discussion of preliminary results in two areas: the effects of temperature and loading rate for woven composites, and the effects of matrix toughening in woven and unidirectional composites.

  18. Optimized plasma-deposited fluorocarbon coating for dry release and passivation of thin SU-8 cantilevers

    DEFF Research Database (Denmark)

    Keller, Stephan Urs; Häfliger, Daniel; Boisen, Anja

    2008-01-01

    release of SU-8 cantilevers and membranes with thicknesses down to 2.3 and 1.7 mu m respectively, which is a considerable improvement to what has been achieved by dry release of all-polymer structures to date. Furthermore, chemical reaction of the SU-8 with the fluorocarbon coating during processing leads......Plasma-deposited fluorocarbon coatings are introduced as a convenient method for the dry release of polymer structures. In this method, the passivation process in a deep reactive ion etch reactor was used to deposit hydrophobic fluorocarbon films. Standard photolithography with the negative epoxy...

  19. National Bridge Inventory - National Geospatial Data Asset (NGDA) Bridges

    Data.gov (United States)

    Department of Transportation — The NBI (NTAD 2015) is a collection of information (database) describing the more than 610,000 of the Nation's bridges located on public roads, including Interstate...

  20. Bridge Creek IMW database - Bridge Creek Restoration and Monitoring Project

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The incised and degraded habitat of Bridge Creek is thought to be limiting a population of ESA-listed steelhead (Oncorhynchus mykiss). A logical restoration approach...

  1. General design of Sutong Bridge

    Institute of Scientific and Technical Information of China (English)

    Zhang Xigang; Yuan Hong; Pei Minshan; Dai Jie; Xu Lin

    2009-01-01

    The main span of Sutong Bridge is a double-pylon, double-plane cable-stayed bridge with steel box girder, which has the world's longest central span of 1 088 m within cable-stayed bridges. To overcome problems caused by severe meteorological conditions, perplexing hydrological conditions, deep buried bedrock and higher navigation level, many new technics and methods were created. Keys including structural system, steel box girder, stayed cable, tower, pier, tower foundation, collision avoidance system, wind-resistance, seismic-resistance, structural nonlinear response and structural static stability were presented individually in this paper.

  2. Reliability Assessment of Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Middleton, C. R.

    This paper is partly based on research performed for the Highways Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: concrete bridges". It contains the details of a methodology which can be used to generate Whole Life (WL) reliability...... profiles. These WL reliability profiles may be used to establish revised rules for concrete bridges. This paper is to some extend based on Thoft-Christensen et. al. [1996], Thoft-Christensen [1996] et. al. and Thoft-Christensen [1996]....

  3. Constitutive relationship of ionic polymer-metal composite and static response character of its cantilever setup to voltage

    Institute of Scientific and Technical Information of China (English)

    TANG Hua-ping; NIE Tuo; TANG Yun-jun; YIN Chen-feng; TANG Chun-xi; WANG Qiao-yi

    2008-01-01

    As a new ionic polymer-metal composite (IPMC) for artificial muscle, the mechanical performance parameters and the relationship between the deformation and the electrical parameters of the IPMC were studied. With the digital speckle correlation method, the constitutive relationship of the IPMC was confirmed. With non-contact photography measurement, a cantilever setup was designed to confirm the relationship between the deformation of the IPMC film and the applied voltage. The relationship curve of tip displacement of the IPMC cantilever setup vs the voltage was achieved. The results indicate that the IPMC is isotropic, its elastic modulus is 232 MPa and Poisson ratio is 0.163. The curve achieved from the test of the tip displacement of the IPMC cantilever setup shows that the tip displacement reaches the maximum when the stimulated voltage is 5 V. And the tip displacement descends largely when the frequency of the applied voltage is between 30 mHz and 100 mHz.

  4. SEM in situ MiniCantilever Beam Bending of U-10Mo/Zr/Al Fuel Elements

    Energy Technology Data Exchange (ETDEWEB)

    Mook, William [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Baldwin, Jon K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martinez, Ricardo M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mara, Nathan A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-06-16

    In this work, the fracture behavior of Al/Zr and Zr/dU-10Mo interfaces was measured via the minicantilever bend technique. The energy dissipation rates were found to be approximately 3.7-5 mj/mm2 and 5.9 mj/mm2 for each interface, respectively. It was found that in order to test the Zr/U-10Mo interface, location of the hinge of the cantilever was a key parameter. While this test could be adapted to hot cell use through careful alignment fixturing and measurement of crack lengths with an optical microscope (as opposed to SEM, which was used here out of convenience), machining of the cantilevers via MiniMill in such a way as to locate the interfaces at the cantilever hinge, as well as proper placement of a femtosecond laser notch will continue to be key challenges in a hot cell environment.

  5. In silico modeling and investigation of self-heating effects in composite nano cantilever biosensors with integrated piezoresistors

    Science.gov (United States)

    Mathew, Ribu; Ravi Sankar, A.

    2017-03-01

    Over the years, piezoresistive nano cantilever sensors have been extensively investigated for various biological sensing applications. Piezoresistive cantilever sensor is a composite structure with different materials constituting its various layers. Design and modeling of such sensors become challenging since their response is governed by the interplay between their geometrical and constituent material parameters. Even though, piezoresistive nano cantilever biosensors have several advantages, they suffer from a limitation in the form of self-heating induced inaccuracy which is seldom considered in design stages. Although, a few simplified mathematical models have been reported which incorporate the self-heating effect, several assumptions made in the modeling stages result in inaccuracy in predicting sensor terminal response. In this paper, we model and investigate the effect of self-heating on the thermo-electro-mechanical response of piezoresistive cantilever sensors as a function of the relative geometries of the piezoresistor and the cantilever platform. Finite element method (FEM) based numerical computations are used to model the target-receptor interactions induced surface stress response in steady state and maximize the electrical sensitivity to thermal sensitivity ratio of the sensor. Simulation results show that the conduction mode of heat transfer is the dominant heat transfer mechanism. Furthermore, the isolation and immobilization layers play a critical role in determining the thermal sensitivity of the sensor. It is found that the shorter and wider cantilever platforms are more suitable to reduce self-heating induced inaccuracies. In addition, results depict that the piezoresistor width plays a more dominant role in determining the thermal drift induced inaccuracies compared to the piezoresistor length. It is found that for surface stress sensors at large piezoresistor width, the electrical sensitivity to thermal sensitivity ratio improves.

  6. Theoretical investigation of nonlinear resonances in a carbon nanotube cantilever with a tip-mass under electrostatic excitation

    Science.gov (United States)

    Kim, I. K.; Lee, S. I.

    2013-09-01

    The nonlinear dynamics of a resonating carbon nanotube (CNT) cantilever having an attached mass at the tip ("tip mass") were investigated by incorporating electrostatic forces and intermolecular interactions between the CNT and a conducting plane surface. This work enables applications of CNT resonating sensors for tiny mass detection and provides a better understanding of the dynamics of CNT cantilevers. The effect of tip mass on a resonating CNT cantilever is normally characterized by the fundamental frequency shift in the linear resonance regime. However, there are more complex dynamics in the nonlinear resonance regime, such as secondary resonances with parametric excitation. The latter have been limited to nano-cantilevers without tip mass or to axially excited micro-beams. To analyze the nonlinear dynamics, we developed a differential equation model that includes both geometric and inertial nonlinear terms for the large vibration amplitudes at increasing drive forces. In our approach, we used Galerkin discretization techniques and numerical integration methods. The CNT cantilever exhibited complex nonlinear responses due to the applied AC and DC voltages and various tip masses. The nonlinear model had a softer response for increasing tip mass than those of the linear model with the same driving conditions. At low applied voltages, the cantilever had linear amplitude and phase responses at primary and secondary superharmonic resonance frequencies. The response branches were softened at the primary resonance through saddle-node (SN) bifurcation from harmonic electrostatic excitation at higher applied voltages. After SN bifurcation, the lower branch of the solution near resonance became unstable. In addition, theoretical analyses were performed on more complex nonlinear responses and stability changes with tip mass variations, such as period-doubling (PD) bifurcation at subharmonic resonance frequencies.

  7. A short pulse (7 μs FWHM) and high repetition rate (dc-5kHz) cantilever piezovalve for pulsed atomic and molecular beams

    NARCIS (Netherlands)

    Irimia, D.; Dobrikov, D.; Kortekaas, R.; Voet, H.; Ende, D.A. van den; Groen, W.A.; Janssen, M.H.M.

    2009-01-01

    In this paper we report on the design and operation of a novel piezovalve for the production of short pulsed atomic or molecular beams. The high speed valve operates on the principle of a cantilever piezo. The only moving part, besides the cantilever piezo itself, is a very small O-ring that forms t

  8. The Higgs Bridge

    CERN Document Server

    Allen, Roland E

    2013-01-01

    The particle recently discovered at the Large Hadron Collider near Geneva is almost certainly a Higgs boson, the long-sought completion of the Standard Model of particle physics. But this discovery, an achievement by more than six thousand scientists (including students), is actually much more than a mere capstone of the Standard Model. It instead represents a bridge from the Standard Model to exciting discoveries of the future, at higher energies or in other experiments, and to the properties of matter at very low temperatures. The mere existence of a particle with zero spin implies a need for new physics, with the most likely candidate being supersymmetry, which requires that every known particle has a superpartner yet to be discovered. And phenomena similar to the Higgs are seen in superconducting metals and superfluid gases at low temperatures, which extend down to a millionth or even a billionth of a degree Kelvin. So the discovery of a Higgs boson has a central place in our attempts both to achieve a tr...

  9. Mineral bridges in nacre revisited

    CERN Document Server

    Checa, Antonio G; Willinger, Marc-Georg

    2012-01-01

    We confirm with high-resolution techniques the existence of mineral bridges between superposed nacre tablets. In the towered nacre of both gastropods and the cephalopod Nautilus there are large bridges aligned along the tower axes, corresponding to gaps (150-200 nm) in the interlamellar membranes. Gaps are produced by the interaction of the nascent tablets with a surface membrane that covers the nacre compartment. In the terraced nacre of bivalves bridges associated with elongated gaps in the interlamellar membrane (> 100 nm) have mainly been found at or close to the edges of superposed parental tablets. To explain this placement, we hypothesize that the interlamellar membrane breaks due to differences in osmotic pressure across it when the interlamellar space below becomes reduced at an advanced stage of calcification. In no cases are the minor connections between superimposed tablets (< 60 nm), earlier reported to be mineral bridges, found to be such.

  10. The stories of two bridges in Ghana

    DEFF Research Database (Denmark)

    Andreasen, Jørgen

    2004-01-01

    Public participation in bridge building was promoted by un habitat in the village of Mankrong. The neighbouring village did not participate in the construction of their bridge. The first flooding washed the second bridge down while the "participative bridge" stood up....

  11. On utilizing delayed feedback for active-multimode vibration control of cantilever beams

    Science.gov (United States)

    Alhazza, Khaled A.; Nayfeh, Ali H.; Daqaq, Mohammed F.

    2009-01-01

    We present a single-input single-output multimode delayed-feedback control methodology to mitigate the free vibrations of a flexible cantilever beam. For the purpose of controller design and stability analysis, we consider a reduced-order model consisting of the first n vibration modes. The temporal variation of these modes is represented by a set of nonlinearly coupled ordinary-differential equations that capture the evolving dynamics of the beam. Considering a linearized version of these equations, we derive a set of analytical conditions that are solved numerically to assess the stability of the closed-loop system. To verify these conditions, we characterize the stability boundaries using the first two vibration modes and compare them to damping contours obtained by long-time integration of the full nonlinear equations of motion. Simulations show excellent agreement between both approaches. We analyze the effect of the size and location of the piezoelectric patch and the location of the sensor on the stability of the response. We show that the stability boundaries are highly dependent on these parameters. Finally, we implement the controller on a cantilever beam for different controller gain-delay combinations and assess the performance using time histories of the beam response. Numerical simulations clearly demonstrate the controller ability to mitigate vibrations emanating from multiple modes simultaneously.

  12. Piezoceramic Cantilever Sensor Design for Weak-Impact Detection on Plates

    Directory of Open Access Journals (Sweden)

    Young-Sup Lee

    2012-01-01

    Full Text Available A piezoelectric cantilever type sensor for locating the precise weak-impact or touch position on a plate is presented in this paper. Since the importance of human-computer interface such as a touch panel system has been rapidly increasing recently, this study could suggest an appropriate sensor for the detection of a weak-impact point effectively and accurately for such a system. This sensor detects the out-of-plane vibration of a panel when a touch with a finger or pen is applied on it. The sensor is made with a steel beam and a single crystal PMN-PT patch is bonded on the beam, which is designed to detect the base vibration of the panel. The sensor was designed, manufactured to verify the detect ability of a weak-impact and attached on two different plates of a glass of 400 × 400 × 4 mm and a wooden MDF of 600 × 600 × 9 mm. The experiment result of the sensor was compared with that of an accelerometer which can also be used for the same purpose and shows clear weak-impact responses with a narrow-band property at its resonant frequency. It is expected that the cantilever type sensor in this study could be applied to make a simple flat plate into a touch panel when the time difference of arrivals method is used to locate the weak-impact point.

  13. Mechanical properties of graphene cantilever from atomic force microscopy and density functional theory.

    Science.gov (United States)

    Rasuli, R; Iraji Zad, A; Ahadian, M M

    2010-05-07

    We have studied the mechanical properties of a few-layer graphene cantilever (FLGC) using atomic force microscopy (AFM). The mechanical properties of the suspended FLGC over an open hole have been derived from the AFM data. Force displacement curves using the Derjaguin-Müller-Toporov (DMT) and the massless cantilever beam models yield a Young modulus of E(c) approximately 37, E(a) approximately 0.7 TPa and a Hamakar constant of approximately 3 x 10( - 18) J. The threshold force to shear the FLGC was determined from a breaking force and modeling. In addition, we studied a graphene nanoribbon (GNR), which is a system similar to the FLGC; using density functional theory (DFT). The in-plane Young's modulus for the GNRs were calculated from the DFT outcomes approximately 0.82 TPa and the results were compared with the experiment. We found that the Young's modulus and the threshold shearing force are dependent on the direction of applied force and the values are different for zigzag edge and armchair edge GNRs.

  14. 2D MEMS electrostatic cantilever waveguide scanner for potential image display application

    Directory of Open Access Journals (Sweden)

    Gu Kebin

    2015-01-01

    Full Text Available This paper presents the current status of our micro-fabricated SU-8 2D electrostatic cantilever waveguide scanner. The current design utilizes a monolithically integrated electrostatic push-pull actuator. A 4.0 μm SU-8 rib waveguide design allows a relatively large core cross section (4μm in height and 20 μm in width to couple with existing optical fiber and a broad band single mode operation (λ= 0.7μm to 1.3μm with minimal transmission loss (85% to 87% output transmission efficiency with Gaussian beam profile input. A 2D scanning motion has been successfully demonstrated with two fundamental resonances found at 202 and 536 Hz in vertical and horizontal directions. A 130 μm and 19 μm, corresponding displacement and 0.062 and 0.009 rad field of view were observed at a +150V input. Beam divergence from the waveguide was corrected by a focusing GRIN lens and a 5μm beam diameter is observed at the focal plane. The transmission efficiency is low (~10% and cantilever is slightly under tensile residual stress due to inherent imperfection in the process and tooling in fabrication. However, 2D light scanning pattern was successfully demonstrated using 1-D push-pull actuation.

  15. Fast on-wafer electrical, mechanical, and electromechanical characterization of piezoresistive cantilever force sensors

    Science.gov (United States)

    Tosolini, G.; Villanueva, L. G.; Perez-Murano, F.; Bausells, J.

    2012-01-01

    Validation of a technological process requires an intensive characterization of the performance of the resulting devices, circuits, or systems. The technology for the fabrication of micro and nanoelectromechanical systems (MEMS and NEMS) is evolving rapidly, with new kind of device concepts for applications like sensing or harvesting are being proposed and demonstrated. However, the characterization tools and methods for these new devices are still not fully developed. Here, we present an on-wafer, highly precise, and rapid characterization method to measure the mechanical, electrical, and electromechanical properties of piezoresistive cantilevers. The setup is based on a combination of probe-card and atomic force microscopy technology, it allows accessing many devices across a wafer and it can be applied to a broad range of MEMS and NEMS. Using this setup we have characterized the performance of multiple submicron thick piezoresistive cantilever force sensors. For the best design we have obtained a force sensitivity ℜF = 158μV/nN, a noise of 5.8 μV (1 Hz-1 kHz) and a minimum detectable force of 37 pN with a relative standard deviation of σr ≈ 8%. This small value of σr, together with a high fabrication yield >95%, validates our fabrication technology. These devices are intended to be used as bio-molecular detectors for the measurement of intermolecular forces between ligand and receptor molecule pairs.

  16. Seatbelt submarining injury and its prevention countermeasures: How a cantilever seat pan structure exacerbate submarining.

    Science.gov (United States)

    Thorbole, Chandrashekhar K

    2015-01-01

    The purpose of this study and a case report was to demonstrate seat belt webbing induced injury due to seatbelt submarining during the frontal motor vehicle crash. Submarining is an undesired phenomenon during a frontal crash scenario and is dependent on design features of the seat pan and seatbelt system. The lack of adequate anti-submarining features at any seating position with three-point restraint can cause abdominal solid and hollow organ injuries. This paper reports a case of submarining and factors that exacerbated this phenomenon leading to critical occupant abdominal injury. This case report and the following injury causation analysis demonstrate the shortcomings of a cantilever seat pan design in context to the occupant safety. The inadequate seat pan anti-submarining feature in association with lack of seatbelt load-limiter and Pretensioner reduces the level of occupant protection offered by the seat belt system in the rear seat. This case report shows the dangers of cantilever seat pan design and its association with increased risk of submarining causing severe abdominal injuries.

  17. An energy harvester combining a piezoelectric cantilever and a single degree of freedom elastic system

    Institute of Scientific and Technical Information of China (English)

    Hong-yan WANG; Xiao-biao SHAN; Tao XIE

    2012-01-01

    This paper presents a type of vibration energy harvester combining a piezoelectric cantilever and a single degree of freedom (SDOF) elastic system.The main function of the additional SDOF elastic system is to magnify vibration displacement of the piezoelectric cantilever to improve the power output.A mathematical model of the energy harvester is developed based on Hamilton's principle and Rayleigh-Ritz method.Furthermore,the effects of the structural parameters of the SDOF elastic system on the electromechanical outputs of the energy harvester are analyzed numerically.The accuracy of the output performance in the numerical solution is identified from the finite element method (FEM).A good agreement is found between the numerical results and FEM results.The results show that the power output can be increased and the frequency bandwidth can be improved when the SDOF elastic system has a larger lumped mass and a smaller damping ratio.The numerical results also indicate that a matching load resistance under the short circuit resonance condition can obtain a higher current output,and so is more suitable for application to the piezoelectric energy harvester.

  18. Crack Identification of Cantilever Plates Based on a Kriging Surrogate Model.

    Science.gov (United States)

    Gao, Haiyang; Guo, Xinglin; Ouyang, Huajiang; Han, Fang

    2013-10-01

    This work presents an effective method to identify the tip locations of an internal crack in cantilever plates based on a Kriging surrogate model. Samples of varying crack parameters (tip locations) and their corresponding root mean square (RMS) of random responses are used to construct the initial Kriging surrogate model. Moreover, the pseudo excitation method (PEM) is employed to speed up the spectral analysis. For identifying crack parameters based on the constructed Kriging model, a robust stochastic particle swarm optimization (SPSO) algorithm is adopted for enhancing the global searching ability. To improve the accuracy of the surrogate model without using extensive samples, a small number of samples are first used. Then an optimal point-adding process is carried out to reduce computational cost. Numerical studies of a cantilever plate with an internal crack are performed. The effectiveness and efficiency of this method are demonstrated by the identified results. The effect of initial sampling size on the precision of the identified results is also investigated.

  19. Electric force microscopy of semiconductors: Theory of cantilever frequency fluctuations and noncontact friction

    Energy Technology Data Exchange (ETDEWEB)

    Lekkala, Swapna; Marohn, John A.; Loring, Roger F., E-mail: roger.loring@cornell.edu [Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853 (United States)

    2013-11-14

    An electric force microscope employs a charged atomic force microscope probe in vacuum to measure fluctuating electric forces above the sample surface generated by dynamics of molecules and charge carriers. We present a theoretical description of two observables in electric force microscopy of a semiconductor: the spectral density of cantilever frequency fluctuations (jitter), which are associated with low-frequency dynamics in the sample, and the coefficient of noncontact friction, induced by higher-frequency motions. The treatment is classical-mechanical, based on linear response theory and classical electrodynamics of diffusing charges in a dielectric continuum. Calculations of frequency jitter explain the absence of contributions from carrier dynamics to previous measurements of an organic field effect transistor. Calculations of noncontact friction predict decreasing friction with increasing carrier density through the suppression of carrier density fluctuations by intercarrier Coulomb interactions. The predicted carrier density dependence of the friction coefficient is consistent with measurements of the dopant density dependence of noncontact friction over Si. Our calculations predict that in contrast to the measurement of cantilever frequency jitter, a noncontact friction measurement over an organic semiconductor could show appreciable contributions from charge carriers.

  20. Analysis of Steady Collision Vibration in Cantilever Beam Having an Attached Mass

    Science.gov (United States)

    Aihara, Tatsuhito; Kumano, Hiroyuki; Hara, Shin-Ichi

    This paper deals with response analysis of collision vibration in continuous system excited by periodic displacement with arbitrary functions. A system of steady vibration in a cantilever beam having an attached mass at free-end is considered. The cantilever beam has structural damping in the beam, and it is being put in the viscous fluid with hydrodynamic drag. The attached mass collides elastically with the coil spring clamped on asymmetrical faces when the amplitude of mass exceeds the clearance between the coil spring and the attached mass. Then, the restoring force is assumed to be an asymmetric piecewise-linear system. For such a system, the beam undergoes a nonlinear vibration when the attached mass collides with the coil spring. In order to analyze harmonic, superharmonic and subharmonic resonances for the system, Fourier series method is applied to obtain an exact solution for resulting vibration. Next, the numerical calculation is performed to obtain the resonance curves. The numerical results show effects of the mass ratio, the amplitude ratio of excitation, the spring constant ratio, the structural damping ratio and the external damping ratio on the resonance curves. The numerical experiments are also carried out to verify the numerical results.

  1. A High-Performance, Low-Cost Laser Shutter using a Piezoelectric Cantilever Actuator

    CERN Document Server

    Bowden, W; Baird, P E G; Gill, P

    2016-01-01

    We report the design and characterization of an optical shutter based on a piezoelectric cantilever. Compared to conventional electro-magnetic shutters, the device is intrinsically low power and acoustically quiet. The cantilever position is controlled by a high-voltage op-amp circuit for easy tuning of the range of travel, and mechanical slew rate, which enables a factor of 30 reduction in mechanical noise compared to a rapidly switched device. We achieve shuttering rise and fall times of 11 $\\mu$s, corresponding to mechanical slew rates of 1.3 $\\textrm{ ms}^{-1}$, with an timing jitter of less than 1 $\\mu$s. When used to create optical pulses, we achieve minimum pulse durations of 250 $\\mu$s. The reliability of the shutter was investigated by operating continuously for one week at 10 Hz switching rate. After this period, neither the shutter delay or actuation speed had changed by a notable amount. We also show that the high-voltage electronics can be easily configured as a versatile low-noise, high-bandwidt...

  2. Design and experimental research on cantilever accelerometer based on fiber Bragg grating

    Science.gov (United States)

    Xiang, Longhai; Jiang, Qi; Li, Yibin; Song, Rui

    2016-06-01

    Currently, an acceleration sensor based on fiber Bragg grating (FBG) has been widely used. A cantilever FBG accelerometer is designed. The simulation of this structure was implemented by finite element software (ANSYS) to analyze its sensing performance parameters. And then the optimized structure was produced and calibration experiments were conducted. On the basis of simulation, optical fiber is embedded in the inner tank of the vibrating mass, and Bragg grating is suspended above the cantilever structure, which can effectively avoid the phenomenon of center wavelength chirp or broadening, and greatly improve the sensitivity of the sensor. The experimental results show that the FBG accelerometer exhibits a sensitivity of 75 pm/(m/s2) (100 Hz) and dynamic range of 60 dB. Its linearity error is <2.31% and repeatability error is <2.76%. And the resonant frequency is ˜125 Hz. The simulation results match the experimental results to demonstrate the good performance of FBG accelerometer, which is expected to be used in the actual project.

  3. Multiple regimes of operation in bimodal AFM: understanding the energy of cantilever eigenmodes.

    Science.gov (United States)

    Kiracofe, Daniel; Raman, Arvind; Yablon, Dalia

    2013-01-01

    One of the key goals in atomic force microscopy (AFM) imaging is to enhance material property contrast with high resolution. Bimodal AFM, where two eigenmodes are simultaneously excited, confers significant advantages over conventional single-frequency tapping mode AFM due to its ability to provide contrast between regions with different material properties under gentle imaging conditions. Bimodal AFM traditionally uses the first two eigenmodes of the AFM cantilever. In this work, the authors explore the use of higher eigenmodes in bimodal AFM (e.g., exciting the first and fourth eigenmodes). It is found that such operation leads to interesting contrast reversals compared to traditional bimodal AFM. A series of experiments and numerical simulations shows that the primary cause of the contrast reversals is not the choice of eigenmode itself (e.g., second versus fourth), but rather the relative kinetic energy between the higher eigenmode and the first eigenmode. This leads to the identification of three distinct imaging regimes in bimodal AFM. This result, which is applicable even to traditional bimodal AFM, should allow researchers to choose cantilever and operating parameters in a more rational manner in order to optimize resolution and contrast during nanoscale imaging of materials.

  4. Fiber faceplate modulation readout in Bi-material micro-cantilever mirror array imaging system

    Science.gov (United States)

    Hui, Mei; Xia, Zhengzheng; Liu, Ming; Dong, Liquan; Liu, Xiaohua; Zhao, Yuejin

    2016-05-01

    Fiber faceplate modulation was applied to read out the precise actuation of silicon-based, surface micro-fabricated cantilever mirrors array in optical imaging system. The faceplate was made by ordered bundles consisting of as many as ten thousands fibers. The transmission loss of an individual fiber in the bundles was 0.35dB/cm and the cross talk between neighboring fibers in the faceplate was about 15%. Micro-cantilever mirrors array (Focal-Plane Array (FPA)) which composed of two-level bi-material pixels, absorb incident infrared flux and result in a temperature increase. The temperature distribution of incident flux transformed to the deformation distribution in FPA which has a very big difference in coefficients of thermal expansion. FPA plays the roles of target sensing and has the characteristics of high detection sensitivity. Instead of general filter such as knife edge or pinhole, fiber faceplate modulate the beam reflected by the units of FPA. An optical readout signal brings a visible spectrum into pattern recognition system, yielding a visible image on monitor. Thermal images at room temperature have been obtained. The proposed method permits optical axis compact and image noise suppression.

  5. Multi frequency excited MEMS cantilever beam resonator for Mixer-Filter applications

    KAUST Repository

    Chandran, Akhil A.

    2016-09-15

    Wireless communication uses Radio Frequency waves to transfer information from one point to another. The modern RF front end devices are implementing MEMS in their designs so as to exploit the inherent properties of MEMS devices, such as its low mass, low power consumption, and small size. Among the components in the RF transceivers, band pass filters and mixers play a vital role in achieving the optimum RF performance. And this paper aims at utilizing an electrostatically actuated micro cantilever beam resonator\\'s nonlinear frequency mixing property to realize a Mixer-Filter configuration through multi-frequency excitation. The paper studies about the statics and dynamics of the device. Simulations are carried out to study the added benefits of multi frequency excitation. The modelling of the cantilever beam has been done using a Reduced Order Model of the Euler-Bernoulli\\'s beam equation by implementing the Galerkin discretization. The device is shown to be able to down-convert signals from 960 MHz of frequency to an intermediate frequency around 50 MHz and 70 MHz in Phase 1 and 2, respectively. The simulation showed promising results to take the project to the next level. © 2016 IEEE.

  6. Nanoscale Mapping of Dielectric Properties of Nanomaterials from Kilohertz to Megahertz Using Ultrasmall Cantilevers.

    Science.gov (United States)

    Cadena, Maria J; Sung, Seung Hyun; Boudouris, Bryan W; Reifenberger, Ronald; Raman, Arvind

    2016-04-26

    Electrostatic force microscopy (EFM) is often used for nanoscale dielectric spectroscopy, the measurement of local dielectric properties of materials as a function of frequency. However, the frequency range of atomic force microscopy (AFM)-based dielectric spectroscopy has been limited to a few kilohertz by the resonance frequency and noise of soft microcantilevers used for this purpose. Here, we boost the frequency range of local dielectric spectroscopy by 3 orders of magnitude from a few kilohertz to a few megahertz by developing a technique that exploits the high resonance frequency and low thermal noise of ultrasmall cantilevers (USCs). We map the frequency response of the real and imaginary components of the capacitance gradient (∂C(ω)/∂z) by using second-harmonic EFM and a theoretical model, which relates cantilever dynamics to the complex dielectric constant. We demonstrate the method by mapping the nanoscale dielectric spectrum of polymer-based materials for organic electronic devices. Beyond offering a powerful extension to AFM-based dielectric spectroscopy, the approach also allows the identification of electrostatic excitation frequencies which affords high dielectric contrast on nanomaterials.

  7. Cantilever tilt causing amplitude related convolution in dynamic mode atomic force microscopy.

    Science.gov (United States)

    Wang, Chunmei; Sun, Jielin; Itoh, Hiroshi; Shen, Dianhong; Hu, Jun

    2011-01-01

    It is well known that the topography in atomic force microscopy (AFM) is a convolution of the tip's shape and the sample's geometry. The classical convolution model was established in contact mode assuming a static probe, but it is no longer valid in dynamic mode AFM. It is still not well understood whether or how the vibration of the probe in dynamic mode affects the convolution. Such ignorance complicates the interpretation of the topography. Here we propose a convolution model for dynamic mode by taking into account the typical design of the cantilever tilt in AFMs, which leads to a different convolution from that in contact mode. Our model indicates that the cantilever tilt results in a dynamic convolution affected by the absolute value of the amplitude, especially in the case that corresponding contact convolution has sharp edges beyond certain angle. The effect was experimentally demonstrated by a perpendicular SiO(2)/Si super-lattice structure. Our model is useful for quantitative characterizations in dynamic mode, especially in probe characterization and critical dimension measurements.

  8. Analysis of film strain and stress in a film-substrate cantilever system

    Institute of Scientific and Technical Information of China (English)

    BAI; Narsu

    2008-01-01

    The bending problem of a magnetic film-nonmagnetic substrate cantilever system is studied by using the principle of energy minimization. Emphasis is placed on the analysis of geometrical and physical parameter dependence of the neutral plane,internal film stress and strain of the cantilever system,and then the influence of such a parameter on the bending characteristic is presented. The results indicate,owing to the anisotropic expanding feature of the magnetostriction,that the neutral plane is generally anisotropic,and moves downwards rapidly with the increasing thickness ratio. Meanwhile,the bounding rigidity of substrate on the film will de-crease with the increasing thickness ratio,and thus release the film stress,i.e.,it decreases,but the film strain increases. The effect of Poisson’s ratio of the materi-als on the film strain,the stress and the neutral plane in the direction transverse to the magnetization is prominent. For the strain and the stress in the magnetization,however,the role of Poisson’s ratio is inconspicuous. This property is due to the initiative elongating (or contracting) feature of the magnetic film along its mag-netization.

  9. Analyzing the vibrational response of an AFM cantilever in liquid with the consideration of tip mass by comparing the hydrodynamic and contact repulsive force models in higher modes

    Science.gov (United States)

    Korayem, Moharam Habibnejad; Nahavandi, Amir

    2017-04-01

    This paper investigates the vibration of a tapping-mode Atomic Force Microscope (AFM) cantilever covered with two whole piezoelectric layers in a liquid medium. The authors of this article have already modeled the vibration of a cantilever immersed in liquid over rough surfaces. Five new ideas have been considered for improving the results of the previous work. Mass and damping of a cantilever probe tip have been considered. Since the probe tip of an AFM cantilever has a mass, which can itself affect the natural frequency of vibration, the significance of this mass has been explored. Also, two hydrodynamic force models for analyzing the mass and damping added to a cantilever in liquid medium have been evaluated. In modeling the vibration of a cantilever in liquid, simplifications are made to the theoretical equations used in the modeling, which may make the obtained results different from those in the real case. So, two hydrodynamic force models are introduced and compared with each other. In addition to the already introduced DMT model, the JKR model has been proposed. The forces acting on a probe tip have attractive and repulsive effects. The attractive Van der Waals force can vary depending on the surface smoothness or roughness, and the repulsive contact force, which is independent of the type of surface roughness and usually varies with the hardness or softness of a surface. When the first mode is used in the vibration of an AFM cantilever, the changes of the existing physical parameters in the simulation do not usually produce a significant difference in the response. Thus, three cantilever vibration modes have been investigated. Finally, an analytical approach for obtaining the response of equations is presented which solves the resulting motion equation by the Laplace method and, thus, a time function is obtained for cantilever deflection is determined. Also, using the COMSOL software to model a cantilever in a liquid medium, the computed natural

  10. Redundancy Evaluation of Fracture Critical Bridges

    OpenAIRE

    Bapat, Amey Vivek

    2014-01-01

    Cases of brittle fractures in major bridges prompted AASHTO to publish its first fracture control plan in 1978. It focused on material and fabrication standards, and required periodic 24-month hands-on inspection of bridges with fracture critical members. The practical result of this plan was to significantly increase the life cycle cost of these bridges, rendering them uneconomical. Apart from the Point Pleasant Bridge that failed in 1967, no other bridge has collapsed in the USA following a...

  11. Environmental life cycle assessment comparison between two bridge types: reinforced concrete bridge and steel composite bridge

    DEFF Research Database (Denmark)

    Du, Guangli; Karoumi, Raid

    2013-01-01

    not been integrated into the decision-making process. This paper presents a systematic LCA method for quantifying the environmental impacts for bridges. The comparison study is performed between a reinforced concrete bridge and a steel bridge as an alternative design, with several key maintenance and EOL...... scenarios outlined. LCA study is performed with the ReCiPe methodology with life cycle inventories data from public database. Five selected mid-point level impact categories and the energy consumption are presented. The result shows that the steel bridge has a better environmental performance due...... to the recycling strategy, while the initial material manufacture is the most dominant phase that contributes large environmental impact in both design solutions....

  12. All-thin-film PZT/FeGa Multiferroic Cantilevers and Their Applications in Switching Devices and Parametric Amplification

    Science.gov (United States)

    Wang, Yi; Onuta, Tiberiu-Dan; Long, Chris; Lofland, Samuel; Takeuchi, Ichiro

    2014-03-01

    We are investigating the characteristics of microfabricated PZT/FeGa multiferroic cantilevers. The cantilevers can be driven by AC or DC magnetic and electric field, and the device response can be read off as a piezo-induced voltage. We can use the multiple input parameters to operate the devices in a variety of manners for different applications. They include electromagnetic energy harvesting, pulse triggered nonlinear memory devices, and parametrically amplified ME sensors. Due to the competition of anisotropy and Zeeman energies, the mechanical resonant frequency of the cantilevers was found to follow a hysteresis behavior with DC bias magnetic field applied in the cantilever easy axis. We can also control and tune the occurrence of nonlinear bifurcation in the frequency spectrum. The resulting hysteresis in the frequency spectrum can be used to make switching devices, where the input can be DC electric and magnetic fields, as well as pulses of AC fields. We have also demonstrated parametric pumping of the response from an AC magnetic field using frequency-doubled AC electric field. The enhanced equivalent ME coefficient is as high as 10 million V/(cm*Oe), when the pumping voltage is very close to a threshold voltage. The quality factor also increases from 2000 to 80000 with pumping.

  13. Lead-Free Piezoelectric MEMS Energy Harvesters of (K,Na)NbO3 Thin Films on Stainless Steel Cantilevers

    Science.gov (United States)

    Tsujiura, Yuichi; Suwa, Eisaku; Kurokawa, Fumiya; Hida, Hirotaka; Suenaga, Kazufumi; Shibata, Kenji; Kanno, Isaku

    2013-09-01

    We fabricated piezoelectric MEMS energy harvesters (EHs) of lead-free (K,Na)NbO3 (KNN) thin films on microfabricated stainless steel cantilevers. The use of metal substrates makes it possible to fabricate thin cantilevers owing to a large fracture toughness compared with Si substrates. KNN films were directly deposited onto Pt-coated stainless steel cantilevers by rf-magnetron sputtering, thereby simplifying the fabrication process of the EHs. From XRD measurement, we confirmed that the KNN films on Pt-coated stainless steel cantilevers had a perovskite structure with a preferential (001) orientation. The transverse piezoelectric coefficient e31f and relative dielectric constant ɛr were measured to be -3.8 C/m2 and 409, respectively. From the evaluation of the power generation performance of a KNN thin-film EH (length: 7.5 mm, width: 5.0 mm, weight of tip mass: 25 mg), we obtained a large average output power of 1.6 µW under vibration at 393 Hz and 10 m/s2.

  14. A scanning probe microscope for magnetoresistive cantilevers utilizing a nested scanner design for large-area scans

    Directory of Open Access Journals (Sweden)

    Tobias Meier

    2015-02-01

    Full Text Available We describe an atomic force microscope (AFM for the characterization of self-sensing tunneling magnetoresistive (TMR cantilevers. Furthermore, we achieve a large scan-range with a nested scanner design of two independent piezo scanners: a small high resolution scanner with a scan range of 5 × 5 × 5 μm3 is mounted on a large-area scanner with a scan range of 800 × 800 × 35 μm3. In order to characterize TMR sensors on AFM cantilevers as deflection sensors, the AFM is equipped with a laser beam deflection setup to measure the deflection of the cantilevers independently. The instrument is based on a commercial AFM controller and capable to perform large-area scanning directly without stitching of images. Images obtained on different samples such as calibration standard, optical grating, EPROM chip, self-assembled monolayers and atomic step-edges of gold demonstrate the high stability of the nested scanner design and the performance of self-sensing TMR cantilevers.

  15. Finite Element Method-based Design and Simulations of Micro-cantilever Platform for Chemical and Bio-sensing Applications

    Directory of Open Access Journals (Sweden)

    R. Agarwal

    2016-09-01

    Full Text Available Micro-electro-mechanical systems (MEMS-based cantilever platform have capability for the detection of chemical and biological agents. This paper reports about the finite element method (FEM based design and simulations of MEMS-based piezoresistor cantilever platform to be used for detection of chemical and biological toxic agents. Bulk micromachining technique is adopted for the realisation of the device structure. MEMS piezoresistive biosensing platforms are having potential for a field-based label-free detection of various types of bio-molecules. Using the MEMMECH module of CoventorWare® simulations are performed on the designed model of the device and it is observed that principal stress is maximum along the length (among other dimensions of the micro-cantilever and remains almost constant for 90 per cent of the length of the micro-cantilever. The dimensions of piezoresistor are optimised and the output voltage vs. stress analysis for various lengths of the piezoresistor is performed using the MEMPZR module of the CoventorWare®.

  16. Characterization of epitaxial Pb(Zr,Ti)O3 thin films deposited by pulsed laser deposition on silicon cantilevers

    NARCIS (Netherlands)

    Nguyen, M.D.; Nazeer, H.; Karakaya, K.; Pham, S.V.; Steenwelle, R.; Dekkers, M.; Abelmann, L.; Blank, D.H.A.; Rijnders, G.

    2010-01-01

    This paper reports on the piezoelectric-microelectromechanical system micro-fabrication process and the behavior of piezoelectric stacks actuated silicon cantilevers. All oxide layers in the piezoelectric stacks, such as buffer-layer/bottom-electrode/film/top-electrode: YSZ/SrRuO\\3/Pb(Zr, Ti)\\3/SrRu

  17. Method of mechanical holding of cantilever chip for tip-scan high-speed atomic force microscope

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Shingo [Department of Physics, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Uchihashi, Takayuki; Ando, Toshio [Department of Physics, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Bio-AFM Frontier Research Center, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Core Research for Evolutional Science and Technology of the Japan Science and Technology Agency, 7 Goban-cho, Chiyoda-ku, Tokyo 102-0076 (Japan)

    2015-06-15

    In tip-scan atomic force microscopy (AFM) that scans a cantilever chip in the three dimensions, the chip body is held on the Z-scanner with a holder. However, this holding is not easy for high-speed (HS) AFM because the holder that should have a small mass has to be able to clamp the cantilever chip firmly without deteriorating the Z-scanner’s fast performance, and because repeated exchange of cantilever chips should not damage the Z-scanner. This is one of the reasons that tip-scan HS-AFM has not been established, despite its advantages over sample stage-scan HS-AFM. Here, we present a novel method of cantilever chip holding which meets all conditions required for tip-scan HS-AFM. The superior performance of this novel chip holding mechanism is demonstrated by imaging of the α{sub 3}β{sub 3} subcomplex of F{sub 1}-ATPase in dynamic action at ∼7 frames/s.

  18. Characterization of epitaxial Pb(Zr,Ti)O3 thin films deposited by pulsed laser deposition on silicon cantilevers

    NARCIS (Netherlands)

    Nguyen, M.D.; Nazeer, H.; Karakaya, K.; Pham, S.V.; Steenwelle, R.; Dekkers, M.; Abelmann, L.; Blank, D.H.A.

    2010-01-01

    This paper reports on the piezoelectric-microelectromechanical system micro-fabrication process and the behavior of piezoelectric stacks actuated silicon cantilevers. All oxide layers in the piezoelectric stacks, such as buffer-layer/bottom-electrode/film/top-electrode: YSZ/SrRuO3/Pb(Zr,Ti)3/SrRuO3,

  19. Multi-cracks identification method for cantilever beam structure with variable cross-sections based on measured natural frequency changes

    Science.gov (United States)

    Zhang, Kai; Yan, Xiaojun

    2017-01-01

    Cantilever beam's crack identification can provide critical information which is helpful to determine whether the structure be healthy or not. Among all crack identification methods, the methods based on measured structure's natural frequency changes own advantages of simplicity and easy for operation in practical engineering. To accurately identify multi-cracks' characteristics for cantilever beam structure with variable cross-sections, a mathematical model, which is based on the concept of modal strain energy, is established in this investigation. And to obtain cantilever beam's natural frequency result with higher resolution, a signal processing method based on Hilbert-Huang Transform (HHT) is also proposed, which can overcome the disadvantage of fast Fourier transform (FFT) in the aspect of frequency resolution and incapability of handling nonlinear vibration caused by crack breathing phenomenon. Based on above mathematical model and signal processing method, the method of identifying multi-cracks on cantilever beam with variable cross-sections is presented. To verify the accuracy of this multi-cracks identification method, experimental examples are conducted, and the results show that the method proposed in this investigation can accurately identify the cracks' characteristics, including their locations and relative depths.

  20. A longitudinal thermal actuation principle for mass detection using a resonant micro -cantilever in a fluid medium

    DEFF Research Database (Denmark)

    Grigorov, Alexander; Davis, Zachary James; Rasmussen, Peter

    2004-01-01

    We propose a new thermal actuation mechanical principle, which allows dynamic actuation in most media: air, water, etc. It is used to excite a cantilever, aiming to perform mass detection using resonance shifts, in place of the electrostatic or magnetic actuation that are normally used. It differ...

  1. High-throughput characterization of stresses in thin film materials libraries using Si cantilever array wafers and digital holographic microscopy.

    Science.gov (United States)

    Lai, Y W; Hamann, S; Ehmann, M; Ludwig, A

    2011-06-01

    We report the development of an advanced high-throughput stress characterization method for thin film materials libraries sputter-deposited on micro-machined cantilever arrays consisting of around 1500 cantilevers on 4-inch silicon-on-insulator wafers. A low-cost custom-designed digital holographic microscope (DHM) is employed to simultaneously monitor the thin film thickness, the surface topography and the curvature of each of the cantilevers before and after deposition. The variation in stress state across the thin film materials library is then calculated by Stoney's equation based on the obtained radii of curvature of the cantilevers and film thicknesses. DHM with nanometer-scale out-of-plane resolution allows stress measurements in a wide range, at least from several MPa to several GPa. By using an automatic x-y translation stage, the local stresses within a 4-inch materials library are mapped with high accuracy within 10 min. The speed of measurement is greatly improved compared with the prior laser scanning approach that needs more than an hour of measuring time. A high-throughput stress measurement of an as-deposited Fe-Pd-W materials library was evaluated for demonstration. The fast characterization method is expected to accelerate the development of (functional) thin films, e.g., (magnetic) shape memory materials, whose functionality is greatly stress dependent.

  2. The Akashi Kaikyo Bridge and the Storebælt Bridge

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    1999-01-01

    With the completion of the Akashi Kaikyo Bridge and the Storebælt East Bridge the development of the suspension bridge technology in the 20th century has manifested itself in two impressive structures. With the present echnology may bridges of similar (and also more modest) dimensions...... will undoubtedly be built far into the next century. For bridges going beyond the spans of existing bridges it is, however, likely that new concepts will be developed....

  3. River ice jams at bridges

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, D. [New Brunswick Dept. of Transportation, Fredericton, NB (Canada); Beltaos, S. [National Water Research Institute, Burlington, ON (Canada)

    2000-12-01

    Ice jamming, known to cause high water levels at even moderate river flows, is described as both the main and least understood source of ice-related bridge damages. This paper describes a joint study by the New Brunswick Department of Transportation, the Department of the Environment, local governments, and the National Water Research Institute, designed to address problems associated with the interaction of ice jams and bridges. The study consists of collecting information at each of four sites in New Brunswick including: historical data on ice jam locations, causes, and water levels; channel bathymetry, width and slope within each study centred at the respective bridge; and documentation of ice conditions throughout the ice season, including measurement of ice cover thickness, observation of breakup mechanisms, times, causes, characteristics and possible impacts of ice jam release. Data analysis will include determination of high stages due to ice jams or surges caused by upstream ice jam releases, scour potential of surges, and quantification of the structure's capacity to restrain ice movement and to cause jams. The principal objective of the study is to advance beyond empiricism and to develop rational design criteria for bridges by anticipating the effects of climate changes and by incorporating local meteorological and hydrometric records into bridge design for added safety.

  4. Floating liquid bridge charge dynamics

    Science.gov (United States)

    Teschke, Omar; Soares, David Mendez; Gomes, Whyllerson Evaristo; Valente Filho, Juracyr Ferraz

    2016-01-01

    The interaction of liquid with electric fields is investigated in a configuration where up to 13 kV are applied between electrodes resulting in a 106 V/m electric field in the capillaries and where there is the formation of a free-standing fluid bridge in the interelectrode gap. The Mott-Gurney equation was fitted to the measured ionization current vs applied voltage curve which indicates that the ionization rate at the high-voltage anode electrode dimethylsulfoxide (DMSO) interface and space charging in the interelectrode gap determine the floating liquid bridge current for a given cathode-to-anode voltage. Space charge effects were measured in the cathode becker and also at the liquid bridge since the ionized charges at the anode migrate to the bridge outer surface and decrease the interfacial tension from 43 mJ/m2 to 29 mJ/m2. Two distinct structural regions then form the bridge, a charged plastic (bulk modulus ˜100 MPa) conducting outer layer with a surface conductivity of ˜10-9 Ω-1, which shapes and supports the floating fluid structure, and an inner liquid cylinder, where DMSO molecules flow.

  5. A strange bridge by Leonardo

    CERN Document Server

    Huylebrouck, Dirk

    2013-01-01

    On folio 855 recto of the Codex Atlanticus, Leonardo da Vinci drew three 'easily movable' bridges, but one of them is enigmatic: all 'replicas' in Leonardo museums and exhibitions come as a surprise, to say the least, to any engineer or architect whose attention is drawn to it. This is the case for models in Amboise (France), Chicago and Portland (USA), Florence (Italy) and for the one of the traveling exhibition by the Australian company 'Grande Exhibitions' that already visited 40 major cities in the world. All 'replicas' of the bridge model attributed to Leonardo have pillars standing on the deck of the bridge, while the deck is suspended by cables attached on these pillars. At first sight this problem does not catch the attention of the observer, as the bridge seems to be a mixed form of a beam and a suspension bridge, but it was not overlooked by my colleague architect-engineer Dr. Laurens Luyten (Gent, Belgium). Yet, after a TV-interview in Brussels so much pressure was exerted by some of the museum col...

  6. Robust energy harvesting from walking vibrations by means of nonlinear cantilever beams

    Science.gov (United States)

    Kluger, Jocelyn M.; Sapsis, Themistoklis P.; Slocum, Alexander H.

    2015-04-01

    In the present work we examine how mechanical nonlinearity can be appropriately utilized to achieve strong robustness of performance in an energy harvesting setting. More specifically, for energy harvesting applications, a great challenge is the uncertain character of the excitation. The combination of this uncertainty with the narrow range of good performance for linear oscillators creates the need for more robust designs that adapt to a wider range of excitation signals. A typical application of this kind is energy harvesting from walking vibrations. Depending on the particular characteristics of the person that walks as well as on the pace of walking, the excitation signal obtains completely different forms. In the present work we study a nonlinear spring mechanism that is composed of a cantilever wrapping around a curved surface as it deflects. While for the free cantilever, the force acting on the free tip depends linearly on the tip displacement, the utilization of a contact surface with the appropriate distribution of curvature leads to essentially nonlinear dependence between the tip displacement and the acting force. The studied nonlinear mechanism has favorable mechanical properties such as low frictional losses, minimal moving parts, and a rugged design that can withstand excessive loads. Through numerical simulations we illustrate that by utilizing this essentially nonlinear element in a 2 degrees-of-freedom (DOF) system, we obtain strongly nonlinear energy transfers between the modes of the system. We illustrate that this nonlinear behavior is associated with strong robustness over three radically different excitation signals that correspond to different walking paces. To validate the strong robustness properties of the 2DOF nonlinear system, we perform a direct parameter optimization for 1DOF and 2DOF linear systems as well as for a class of 1DOF and 2DOF systems with nonlinear springs similar to that of the cubic spring that are physically realized

  7. Design of T-Frame Bridge of Mashui River Bridge%马水河特大桥T形刚构桥设计

    Institute of Scientific and Technical Information of China (English)

    陈晓波

    2011-01-01

    Mashui River Bridge is a long span T-frame bridge with span arrangement (116 +116) m. The main girder of the bridge is a prestressed concrete girder of variable section, having a single cell single box and vertical webs. The top of the girder is 10.7 m in width and the bottom varies in round arc. The main pier of the bridge is 108 m high and the pier shaft is the high-rise rectangular hollow pier that has no solid section close to the top of the pier and is connected with the girder in a way of spatial frame. The foundation for the pier is composed of 24 nos. of φ2.5 m reinforced concrete bored piles, the concrete for the piles is of C30 and a 7.5 m high training dike is set at the footing of the pier. The BSAS and ANSYS are respectively used to conduct the structural static force calculation and spatial static and dynamic force analysis. The results of the calculation and analysis show that the static force, wind resistance, seismic resistance and dynamic response of the vehicle and bridge can all satisfy the relevant requirements in the codes. The pier shaft of the bridge is constructed by the backward inclined cantilever formwork and the main girder is constructed by the free balanced cantilever concreting method.%马水河特大桥为(116+116)m的大跨度T形刚构桥.主梁采用变截面预应力混凝土箱梁,单箱单室直腹板,箱梁顶宽10.7 m,梁底缘按圆弧变化.主墩高108 m,墩身采用矩形空心高墩,墩顶不设实体段,与梁部按空间框架形式相接,桩基采用24-φ2.5 m钢筋混凝土钻孔桩,混凝土强度等级为C30,在墩底设置7.5 m高的导流堤.分别采用BSAS和ANSYS对全桥进行结构静力计算及空间静力和动力分析.分析结果表明:该桥静力、抗风、抗震、车桥动力响应验算结果均满足规范要求.该桥主墩墩身采用后倾式悬臂模板法施工,主梁采用对称悬臂浇筑法施工.

  8. 电车接触网腕臂的计算%On Calculation of Trolley Catenary Cantilever

    Institute of Scientific and Technical Information of China (English)

    李艾

    2015-01-01

    The "three elements" of electrification railway include catenary, electric locomotive and traction substation. This paper expounded the calculation of the length of cantilever of catenary trolley in railway electrification with a speed of 200 km/h, calculation accuracy of catenary is related to the reliability of the contact wire suspension, so the calculation of catenary is the basic working content of the design , its calculation is mainly divided into the calculation of cantilever and the calculation of the load of catenary. This paper analyzed the methods to calculate the length of cantilever,it ,mainly introduced the calculation of the length of cantilever,the length of transition mast and newel cantilever in the curve seg-ments of the roads.%电气化铁道的“三大元件”分为接触网、电力机车和牵引变电所。本论文论述时速200Km/h高速电气化铁路的接触网电车接触网腕臂的计算,接触网的计算精确程度就关系到接触线悬挂的可靠程度,故接触网计算是设计中基础的工作内容,其计算主要分为腕臂的计算和接触网的负载计算。文章详细分析了腕臂长度的计算方法,重点介绍了路基曲线区段腕臂长度、转换柱和中心柱腕臂长度的计算。

  9. A micro-cantilever sensor chip based on contact angle analysis for a label-free troponin I immunoassay.

    Science.gov (United States)

    Yin, Tsung-I; Zhao, Yunpeng; Horak, Josef; Bakirci, Huseyin; Liao, Hsin-Hao; Tsai, Hann-Huei; Juang, Ying-Zong; Urban, Gerald

    2013-03-07

    Cantilever sensors have been extensively explored as a promising technique for real-time and label-free analyses in biological systems. A major sensing principle utilized by state-of-the-art cantilever sensors is based on analyte-induced surface stress changes, which result in static bending of a cantilever. The sensor performance, however, suffers from the intrinsically small change in surface stress induced by analytes, especially for molecular recognition such as antigen-antibody binding. Through the contact angle change on a tailored solid surface, it is possible to convert a tiny surface stress into a capillary force-a much larger physical quantity needed for a practical sensor application. In this work, a micro-cantilever sensor based on contact angle analysis (CAMCS) was proposed to effectively enhance the sensitivity of a sensor in proportion to the square of the length to thickness ratio of the cantilever structure. CAMCS chips were fabricated using a standard complementary-metal-oxide-semiconductor (CMOS) process to demonstrate a 1250-fold enhancement in the sensitivity of surface stress to bioanalyte adsorption using a piezoresistive sensing method. A real-time and label-free troponin I (cTnI) immunoassay, which is now widely used in clinics and considered a gold standard for the early diagnosis and prognosis of cardiovascular disease, was performed to demonstrate cTnI detection levels as low as 1 pg mL(-1). The short detection time of this assay was within several minutes, which matches the detection time of commercially available instruments that are based on fluorescence-labeling techniques.

  10. Thermal bridges of modern windows

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan de Place; Møller, Eva B.; Nielsen, Anker

    2013-01-01

    With its focus on reduced energy consumption, contemporary housing construction requires a highly insulated and airtight building envelope with as few thermal bridges as possible.Windows must be carefully designed, as thermal bridges can lead to surface condensation or mold growth, even...... if the window has an U-factor of 1 W/(m2·K) or lower. This paper describes the development of modern, energy efficient Danish windows with reduced thermal bridges. It focuses on materials, geometry, and sealing of window panes based on a literature review. Examples of modern windows are presented. Experience...... with the minimum acceptable surface temperature regarding surface condensation or mold growth, implemented in the Danish Building Regulations in 2010, and the calculation method for this temperature based on international standards is discussed. The introduction of the minimum acceptable surface temperature has...

  11. An Expert System for Concrete Bridge Management

    DEFF Research Database (Denmark)

    Brito, J. de; Branco, F. A.; Thoft-Christensen, Palle

    1997-01-01

    management systems are presently being implemented by bridge authorities in several countries. The prototype of an expert system for concrete bridge management is presented in this paper, with its functionality relying on two modules. The inspection module relies on a periodic acquisition of field......The importance of bridge repair versus new bridge construction has risen in recent decades due to high deterioration rates that have been observed in these structures. Budgets both for building new bridges and keeping the existing ones are always limited. To help rational decision-making, bridge...

  12. Inertia Force Identification of Cantilever under Moving-Mass by Inverse Method

    Directory of Open Access Journals (Sweden)

    Qiang Chen

    2012-12-01

    Full Text Available In this paper, a recursive inverse method is applied to solve the identification problem of inertia force between the cantilever and moving mass. The recursive inverse method consists of two parts: Kalman filter and recursive least-square algorithm. The basic Euler-Bernoulli beam model is introduced. Then, the differential equations and the state space model of the modal responses and the inertia force can be obtained. Finally, the recursive inverse method, which is based on the discretized state function of the system, is adapted. The identification results show that the recursive inverse method is suitable to be adapted in this problem. Some characteristics of the identification results are discussed and some further conclusions are reached.

  13. Impact Response of Cantilever Fiber Metal Laminate (FML Plates Using a Coupled Analytical-Numerical Method

    Directory of Open Access Journals (Sweden)

    Faramarz Ashenai Ghasemi

    2013-05-01

    Full Text Available In this study, dynamic response of cantilever Fiber Metal Laminate (FML plates subjected to the impact of a large mass is studied. Aluminum (Al sheets are placed instead of some Fiber Reinforced Plastic (FRP layers. The effect of the Al layers on contact force and deflection of the plates is investigated by considering the interaction between the impactor and the target in the impact analysis. A two degrees-of-freedom system consisting of springs-masses and finite element modeling of the ABAQUS/Explicit software were employed to model the interaction between the impactor and the target. The results indicate that some parameters like the layer sequence, mass and velocity of the impactor, mass of the target are important factors which affect the impact response of the plates.

  14. Note: High-efficiency broadband acoustic energy harvesting using Helmholtz resonator and dual piezoelectric cantilever beams.

    Science.gov (United States)

    Yang, Aichao; Li, Ping; Wen, Yumei; Lu, Caijiang; Peng, Xiao; He, Wei; Zhang, Jitao; Wang, Decai; Yang, Feng

    2014-06-01

    A high-efficiency broadband acoustic energy harvester consisting of a compliant-top-plate Helmholtz resonator (HR) and dual piezoelectric cantilever beams is proposed. Due to the high mechanical quality factor of beams and the strong multimode coupling of HR cavity, top plate and beams, the high efficiency in a broad bandwidth is obtained. Experiment exhibits that the proposed harvester at 170-206 Hz has 28-188 times higher efficiency than the conventional harvester using a HR with a piezoelectric composite diaphragm. For input acoustic pressure of 2.0 Pa, the proposed harvester exhibits 0.137-1.43 mW output power corresponding to 0.035-0.36 μW cm(-3) volume power density at 170-206 Hz.

  15. Simulation of an ultralow-power power management circuit for MEMS cantilever piezoelectric vibration energy harvesters

    Science.gov (United States)

    Takei, Ryohei; Okada, Hironao; Makimoto, Natsumi; Itoh, Toshihiro; Kobayashi, Takeishi

    2016-10-01

    We developed a power management circuit for piezoelectric microelectromechanical system cantilever vibration energy harvesters (VEHs) with ultralow-power consumption. The power management circuit was effective in a wireless vibration monitoring system. To operate the system, ultralow-power electronics were required because only a small amount of electrical power was generated from the faint environmental vibration. Pb(Zr,Ti)O3 (PZT) and aluminum nitride (AlN) VEHs were fabricated and their equivalent circuits were extracted from output voltage measurements. The power management circuit was simulated using the extracted circuits. The simulation suggested that the power management circuit can be driven by a vibration acceleration of 1.0 m/s2 by lowering the power consumption of the power management circuit using existing electronics.

  16. ANALYSIS ON THE MAGNETO-ELASTIC-PLASTIC BUCKLING/SNAPPING OF CANTILEVER RECTANGULAR FERROMAGNETIC PLATES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An analysis of buckling/snapping and bending behaviors of magneto-elastic-plastic interaction and coupling for cantilever rectangular soft ferromagnetic plates is presented. Based on the expression of magnetic force from the variational principle of ferromagnetic plates, the buckling and bending theory of thin plates, the Mises yield criterion and the increment theory for plastic deformation, we establish a numerical code to quantitatively simulate the behaviors of the nonlinearly multi-fields coupling problems by the finite element method. Along with the phenomena of buckling/snapping and bending, or the characteristic curve of deflection versus magnitude of applied magnetic fields being numerically displayed, the critical loads of buckling/snapping,and the influences of plastic deformation and the width of plate on these critical loads, the plastic regions expanding with the magnitude of applied magnetic field, as well as the evolvement of deflection configuration of the plate are numerically obtained in a case study.

  17. Screen printed PZT/PZT thick film bimorph MEMS cantilever device for vibration energy harvesting

    DEFF Research Database (Denmark)

    Xu, Ruichao; Lei, Anders; Dahl-Petersen, Christian

    2012-01-01

    We present a microelectromechanical system (MEMS) based PZT/PZT thick film bimorph vibration energy harvester with an integrated silicon proof mass. Most piezoelectric energy harvesting devices use a cantilever beam of a non piezoelectric material as support beneath or in-between the piezoelectric...... materials; it provides mechanical support but it also reduces the power output. In our device we replace the support material with another layer of the piezoelectric material. With the absence of an inactive mechanical support all stresses induced by vibrations will be harvested by the active piezoelectric...... elements. We show experimental results from two types PZT/PZT harvesting devices, one where the Pb(ZrxTi1−x)O3 (PZT) thick films are high pressure treated during the fabrication and the other where the treatment is omitted. We find that with the high pressure treatment prior to PZT sintering, the films...

  18. Haptic sensing for MEMS with application for cantilever and Casimir effect

    CERN Document Server

    Calis, M

    2008-01-01

    This paper presents an implementation of the Cosserat theory into haptic sensing technologies for real-time simulation of microstructures. Cosserat theory is chosen instead of the classical theory of elasticity for a better representation of stress, especially in the nonlinear regime. The use of Cosserat theory leads to a reduction of the complexity of the modelling and thus increases its capability for real time simulation which is indispensable for haptic technologies. The incorporation of Cosserat theory into haptic sensing technology enables the designer to simulate in real-time the components in a virtual reality environment (VRE) which can enable virtual manufacturing and prototyping. The software tool created as a result of this methodology demonstrates the feasibility of the proposed model. As test demonstrators, a cantilever microbeam and microbridge undergoing bending in VRE are presented.

  19. FLOW-INDUCED INTERNAL RESONANCES AND MODE EXCHANGE IN HORIZONTAL CANTILEVERED PIPE CONVEYING FLUID (Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    XU Jian; YANG Qian-biao

    2006-01-01

    Based on the nonlinear mathematical model of motion of a horizontally cantilevered rigid pipe conveying fluid, the 3:1 internal resonance induced by the minimum critical velocity is studied in details. With the detuning parameters of internal and primary resonances and the amplitude of the external disturbing excitation varying, the flow in the neighborhood of the critical flow velocity yields that some nonlinearly dynamical behaviors occur in the system such as mode exchange, saddle-node, Hopf and co-dimension 2 bifurcations. Correspondingly, the periodic motion losses its stability by jumping or flutter, and more complicated motions occur in the pipe under consideration.The good agreement between the analytical analysis and the numerical simulation for several parameters ensures the validity and accuracy of the present analysis.

  20. A MEMS-based Air Flow Sensor with a Free-standing Micro-cantilever Structure

    Directory of Open Access Journals (Sweden)

    Che-Ming Chiang

    2007-10-01

    Full Text Available This paper presents a micro-scale air flow sensor based on a free-standingcantilever structure. In the fabrication process, MEMS techniques are used to deposit asilicon nitride layer on a silicon wafer. A platinum layer is deposited on the silicon nitridelayer to form a piezoresistor, and the resulting structure is then etched to create afreestanding micro-cantilever. When an air flow passes over the surface of the cantileverbeam, the beam deflects in the downward direction, resulting in a small variation in theresistance of the piezoelectric layer. The air flow velocity is determined by measuring thechange in resistance using an external LCR meter. The experimental results indicate that theflow sensor has a high sensitivity (0.0284 ω/ms-1, a high velocity measurement limit (45ms-1 and a rapid response time (0.53 s.