Type Inference for Bimorphic Recursion
Tatsuta, Makoto; 10.4204/EPTCS.54.8
2011-01-01
This paper proposes bimorphic recursion, which is restricted polymorphic recursion such that every recursive call in the body of a function definition has the same type. Bimorphic recursion allows us to assign two different types to a recursively defined function: one is for its recursive calls and the other is for its calls outside its definition. Bimorphic recursion in this paper can be nested. This paper shows bimorphic recursion has principal types and decidable type inference. Hence bimorphic recursion gives us flexible typing for recursion with decidable type inference. This paper also shows that its typability becomes undecidable because of nesting of recursions when one removes the instantiation property from the bimorphic recursion.
Thermal vertical bimorph actuators and their applications
Sehr, H J
2002-01-01
In this thesis, a novel concept for lateral actuators based on vertical bimorphs is presented. Vertical bimorphs consist of silicon beams side-coated with aluminium, which bend when heated due to the different thermal expansion coefficients of the two materials causing a displacement in the wafer plane. The heating of the actuator is provided by an electrical current through the silicon beam. The simplest implementation of a vertical bimorph actuator is a clamped-clamped beam. To obtain higher deflections, a meander shaped actuator has been designed. By combining four meander actuators, a two-dimensional positioning stage has been realised. The meander actuator has also been applied for normally closed and normally open micro-relays. Analytical calculations and ANSYS simulations have been carried out to predict the physical behaviour of the bimorph devices, including temperature distribution, static deflection, vertical stiffness, thermal time constant and lateral resonances. For both the clamped-clamped beam...
Conventional ion sources generate energetic ion beams by accelerating the plasma-produced ions through a voltage drop at the extractor, and since it is usual that the ion beam is to propagate in a space which is at ground potential, the plasma source is biased at extractor voltage. For high ion beam energy the plasma source and electrical systems need to be raised to high voltage, a task that adds considerable complexity and expense to the total ion source system. The authors have developed a system which though forming energetic ion beams at ground potential as usual, operates with the plasma source and electronics at ground potential also. Plasma produced by a nearby source streams into a grided chamber that is repetitively pulsed from ground to high positive potential, sequentially accepting plasma into its interior region and ejecting it energetically. They call the device a peristaltic ion source. In preliminary tests they've produced nitrogen and titanium ion beams at energies from 1 to 40 keV. Here they describe the philosophy behind the approach, the test embodiment that they have made, and some preliminary results
Chandler, Joseph A. (Inventor)
1986-01-01
The instant invention is directed to a peristaltic pump for critical laboratory or hospital applications requiring precise flow rates over an extended period of time. Within the cylindrical barrel pump housing is a single-piece, molded, elastometric, cylindrical liner with a multiplicity of flattened helical channels created therein from one end of the liner to the other. Three cylindrical rollers rotate about the center axis of the pump around the inside surface of the liner selectively compressing the liner, and hence the helical channels between the rollers and the barrel housing, creating a pumping action by forcing trapped fluid in the helical channels axially from one end of the liner to the opposite end. The novelty of the invention appears to lie in the provision of the special liner with multiple helical channels as the pumping chamber, rather than the standard single elastomeric tubing which is squeezed repeatedly by rollers to move the liquid through a typical peristaltic pump. Large, repeated deflections on the standard tubing causes a permanent set in the tubing, thus either changing the flow rate, or requiring a new section of tubing to be positioned in the pump head. Further, this configuration minimizes the amount of outflow pulsation which is characteristic of a typical single tubing peristaltic pump.
Performance analysis of piezoelectric bimorph generator
2008-01-01
In this paper,the theoretical model and simulation of the performance of a piezoelectric (PZT)bimorph generator is introduced.The generator consists of two piezoelectric plates bonded on a substrate metal plate.For an effective electromechanical coupling coefficient (EECC) and the generated energy,the analytical formulae are established with the thickness ratio and the Young's modulus ratio as variables.After giving correlative material parameters,the EECC and generated energy can be computed.The results show that there is a optimal thickness ratio for a piezoelectric bimorph generator to achieve the maximum EECC and electrical energy.The EECC and generated energy decrease with an increase of the Young's modulus ratio.In addition,the influence of mechanical source on electrical energy generation and power output is also considered.
TRAVELING MACHINE DRIVEN BY PIEZOELECTRIC BIMORPH
HUA Shunming; CHENG Guangming; FAN Zunqiang; YANG Zhigang; SUZUKI Katsiyoshi
2007-01-01
A rectangular bimorph will vibrate in bending mode under alternating current (AC) electric field. If two opposite tips along longitudinal direction are both clamped, the maximum magnitude of bending displacement occurs on the short center line. Using bimorph type vibrators forementioned as actuators, an invention of simple traveling machine based on stick-slip principle is presented. The machine can not only move along both x and y direction within horizontal working plane, furthermore, excellent bearing ability and agile response as well as stable step are also proved. In addition, the machine can work on stepping mode and scanning mode at the same time, hence the contradiction between long stroke and high precise positioning is solved. Therefore, it meets the needs of micro/nanometer precise positioning under long stroke and is desired to be used as carrying stage for micro-assembling system and locomotive mechanism for miniature robot system.
Design and fabrication of aspherical bimorph PZT optics
Tseng, T C; Yeh, Z C; Perng, S Y; Wang, D J; Kuan, C K; Chen, J R; Chen, C T
2001-01-01
Bimorph piezoelectric optics with a third-order-polynomial surface is designed and a prototype is fabricated as active optics. Two pairs of silicon (Si) and lead zirconate titanate (PZT) piezoelectric ceramic are bonded as Si-PZT-PZT-Si together with a multi-electrode or thin film resistor coating used as the control electrode between Si and PZT and metallic films as grounding between the interface of PZT ceramics. A linear voltage is applied to the bimorph PZT optics by probing the control electrodes from a two-channel controllable power supplier. In doing so, the optics surface can achieve a desired third-order-polynomial surface. Reducing hysteresis and creep in bimorph PZT X-ray optics is the only feasible way by inserting an appropriate capacitor in series with bimorph PZT optics to significantly reduce both effects.
Polymer-Ceramic MEMS Bimorphs as Thermal Infrared Sensors
Warren, Clinton Gregory
2010-01-01
Thermal infrared detectors based on MEMS bimorph beams have the potential to exceed the performance of current uncooled thermal infrared cameras both in terms of sensitivity and cost. These cameras are part of a rapidly growing industry are used for a vast array of applications such as military and civilian night vision, industrial monitoring, and medical imaging. Many researchers have explored the use of metal-ceramic MEMS bimorphs for this application even though it has long been acknowle...
Development of a Micro-Gripper Using Piezoelectric Bimorphs
Nur Azah Hamzaid
2013-05-01
Full Text Available Piezoelectric bimorphs have been used as a micro-gripper in many applications, but the system might be complex and the response performance might not have been fully characterized. In this study the dynamic characteristics of bending piezoelectric bimorphs actuators were theoretically and experimentally investigated for micro-gripping applications in terms of deflection along the length, transient response, and frequency response with varying driving voltages and driving signals. In addition, the implementation of a parallel micro-gripper using bending piezoelectric bimorphs was presented. Both fingers were actuated separately to perform mini object handling. The bending piezoelectric bimorphs were fixed as cantilevers and individually driven using a high voltage amplifier and the bimorph deflection was measured using a non contact proximity sensor attached at the tip of one finger. The micro-gripper could perform precise micro-manipulation tasks and could handle objects down to 50 µm in size. This eliminates the need for external actuator extension of the microgripper as the grasping action was achieved directly with the piezoelectric bimorph, thus minimizing the weight and the complexity of the micro-gripper.
Development of a high performance peristaltic micropump
Pham, My; Goo, Nam Seo
2008-03-01
In this study, a high performance peristaltic micropump has been developed and investigated. The micropump has three cylinder chambers which are connected through micro-channels for high pumping pressure performance. A circular-shaped mini LIPCA has been designed and manufactured for actuating diaphragm. In this LIPCA, a 0.1mm thickness PZT ceramic is used as an active layer. As a result, the actuator has shown to produce large out of plane deflection and consumed low power. During the design process, a coupled field analysis was conducted to predict the actuating behavior of a diaphragm and pumping performance. MEMS technique was used to fabricate the peristaltic micropump. Pumping performance of the present micropump was investigated both numerically and experimentally. The present peristaltic micropump was shown to have higher performance than the same kind of micropump developed else where.
Surface micromachined electrostatically actuated micro peristaltic pump
Xie, Jun; Shih, Jason; Lin, Qiao; Yang, Bozhi; Tai, Yu-Chong
2004-01-01
An electrostatically actuated micro peristaltic pump is reported. The micro pump is entirely surface micromachined using a multilayer parylene technology. Taking advantage of the multilayer technology, the micro pump design enables the pumped fluid to be isolated from the electric field. Electrostatic actuation of the parylene membrane using both DC and AC voltages was demonstrated and applied to fluid pumping based on a 3-phase peristaltic sequence. A maximum flow rate of 1.7 nL min^–1 and a...
Piezoelectric Energy Harvesting Using PZT Bimorphs and Multilayered Stacks
Panda, Prasanta Kumar; Sahoo, Benudhar; Chandraiah, M.; Raghavan, Sreekumari; Manoj, Bindu; Ramakrishna, J.; Kiran, P.
2015-11-01
Piezoelectric materials have a unique ability to interchange electrical and mechanical energy. This property allows the absorption of mechanical energy such as ambient vibration and its transformation into electrical energy. The electrical energy generated can be used to power low-power electronic devices. In the present study, energy harvesting by lead zirconate titanate (PZT) multilayer (ML) stacks and bimorphs is presented. The devices were fabricated by a tape casting technique and were poled at 2 kV/mm for 30 min immersed in a silicone oil bath maintained at 60°C. The energy harvesting characteristics of the fabricated devices were measured in a suitably assembled test setup. The output voltage obtained from the PZT bimorphs and ML stacks was 450 mV and 125 mV, respectively. The higher output voltage from the bimorph is due to its low capacitance.
Bimorph based Active Joints for Nanometre scale Actuation
Chakkalakkal Abdulla, S.M.; Krijnen, G.J.M.
2007-01-01
In this work the modelling of a micro bimorph cantilever which is composed of a Silicon Nitride cantilever beam coated on top with a thin Chromium layer is described. The structure functions as a vertical electrostatic actuator for nanometre displacements with stress induced upward curvature in the
Linear peristaltic pump based on electromagnetic actuators
Maddoui Lotfi
2014-01-01
Full Text Available In this paper a study and design of a linear peristaltic pump are presented. A set of electromagnetic (solenoid actuators is used as the active tools to drag the liquid by crushing an elastic tube. The pump consists of six serially-connected electromagnetic actuators controlled via an electronic board. This may be considered as a simulated peristalsis action of intestines. The dynamic performances of the pump are investigated analytically and experimentally.
A parallel leaf spring structure driven by piezoelectric bimorph actuators
Seki, Hiroya; Gohda, Tomio; Shimokohbe, Akira
A parallel leaf spring structure driven by piezoelectric bimorph actuator is modelled using a Rayleigh-Ritz formulation and model truncation is done for feedback controller design. Using a strain gauge sensor, a precise positioning of the end point mass is realized. The position of the strain gauge sensor is found to be an important factor in achieving a stable response with an estimator based feedback control system. Also excitation of higher structural modes, which becomes an obstacle to a wide servo bandwidth actuator, is discussed. Using multi electrodes arranged on the bimorph actuator and appropriately tuning the voltage ratio applied to them, pole-zero cancellation of the higher modes is experimentally demonstrated.
Peristaltic pumps work in nano scales
Farahpour, Farnoush; Ejtehadi, Mohammad Reza
2013-01-01
A design for a pump is suggested which is based on well-known peristaltic pumps. In order to simply describe the operation of the proposed pump, an innovative interpretation of low Reynolds number swimmers is presented and thereafter a similar theoretical model would be suggested to quantify the behavior of the pumps. A coarse-grained molecular dynamic simulation is used to examine the theoretical predictions and measure the efficiency of the pump in nano scales. It is shown that this pump wi...
Peristaltic Transport through Eccentric Cylinders: Mathematical Model
Kh. S. Mekheimer
2013-01-01
Full Text Available This paper discusses the effect of peristaltic transport on the fluid flow in the gap between two eccentric tubes (eccentric-annulus flows. The inner tube is uniform, rigid, while the outer tube has a sinusoidal wave traveling down its wall. The flow analysis has been developed for low Reynolds number and long wave length approximation. The velocity and the pressure gradient have been obtained in terms of the dimensionless flow rate Q¯, time t, azimuthal coordinate θ and eccentricity parameter ϵ (the parameter that controls of the eccentricity of the inner tube position. The results show that there is a significant deference between eccentric and concentric annulus flows.
Electromechanical properties of nanotube PVA composite actuator bimorphs
Bartholome, Christèle; Derré, Alain; Roubeau, Olivier; Zakri, Cécile; Poulin, Philippe
2008-08-01
Oxidized multiwalled carbon nanotube (oxidized-MWNT)/polyvinyl alcohol (PVA) composite sheets have been prepared for electromechanical actuator applications. MWNT have been oxidized by nitric acid treatments. They were then dispersed in water and mixed with various amounts of PVA of high molecular weight (198 000 g mol-1). The composite sheets were then obtained through a membrane filtration process. The composition of the systems has been optimized to combine suitable mechanical and electrical properties. Thermogravimetric analysis, mechanical tensile tests and conductivity measurements show that the best compromise of mechanical and electrical properties was obtained for a PVA weight fraction of about 30 wt%. In addition, one face of the sheets was coated with gold to increase the conductivity of the sheets and promote uniform actuation. Pseudo-bimorph devices have been realized by subsequently coating the composite sheets with an inert layer of PVA. The devices have been tested electromechanically in a liquid electrolyte (tetrabutylammonium/tetrafluoroborate (TBA/TFB) in acetonitrile) at constant frequency and different applied voltages, from 2 to 10 V. Measurements of the bimorph deflections were used to determine the stress generated by the nanotube-PVA sheets. The results show that the stress generated increases with increasing amplitude of the applied voltage and can reach 1.8 MPa. This value compares well with and even exceeds the stress generated by recently obtained bimorphs made of gold nanoparticles.
Electromechanical properties of nanotube-PVA composite actuator bimorphs
Bartholome, Christele; Derre, Alain; Roubeau, Olivier; Zakri, Cecile; Poulin, Philippe [Centre de Recherche Paul Pascal-CNRS, Avenue Schweitzer 33600 Pessac (France)], E-mail: bartholo@crpp-bordeaux.cnrs.fr, E-mail: derre@crpp-bordeaux.cnrs.fr, E-mail: roubeau@crpp-bordeaux.cnrs.fr, E-mail: zakri@crpp-bordeaux.cnrs.fr, E-mail: poulin@crpp-bordeaux.cnrs.fr
2008-08-13
Oxidized multiwalled carbon nanotube (oxidized-MWNT)/polyvinyl alcohol (PVA) composite sheets have been prepared for electromechanical actuator applications. MWNT have been oxidized by nitric acid treatments. They were then dispersed in water and mixed with various amounts of PVA of high molecular weight (198 000 g mol{sup -1}). The composite sheets were then obtained through a membrane filtration process. The composition of the systems has been optimized to combine suitable mechanical and electrical properties. Thermogravimetric analysis, mechanical tensile tests and conductivity measurements show that the best compromise of mechanical and electrical properties was obtained for a PVA weight fraction of about 30 wt%. In addition, one face of the sheets was coated with gold to increase the conductivity of the sheets and promote uniform actuation. Pseudo-bimorph devices have been realized by subsequently coating the composite sheets with an inert layer of PVA. The devices have been tested electromechanically in a liquid electrolyte (tetrabutylammonium/tetrafluoroborate (TBA/TFB) in acetonitrile) at constant frequency and different applied voltages, from 2 to 10 V. Measurements of the bimorph deflections were used to determine the stress generated by the nanotube-PVA sheets. The results show that the stress generated increases with increasing amplitude of the applied voltage and can reach 1.8 MPa. This value compares well with and even exceeds the stress generated by recently obtained bimorphs made of gold nanoparticles.
Mems-based pzt/pzt bimorph thick film vibration energy harvester
Xu, Ruichao; Lei, Anders; Dahl-Petersen, Christian;
2011-01-01
We describe fabrication and characterization of a significantly improved version of a MEMS-based PZT/PZT thick film bimorph vibration energy harvester with an integrated silicon proof mass. The main advantage of bimorph vibration energy harvesters is that strain energy is not lost in mechanical...
A linear peristaltic MRF/foam actuator
Larsen, J. J.; Jenkins, C. H.; Korde, U. A.
2007-04-01
, peristaltic pumps in industry are common for a variety of material handling applications, particularly involving the movement of sterile fluids (for example, blood). The peristaltic pump is usually circular in configuration, relying on external rollers to move fluid within a tube. Some linear configuration pumps have been proposed and developed, however they are complicated than their circular counterparts. In the remaining part of the present work, we discuss the development of a linear peristaltic actuator based upon the deformation of MRF/foam. The actuator consists of an open-cell polymer foam substrate infused with MRF. To one side of the foam substrate resides a translating magnet, such that a magnetic field can be propagated down its length. The linear peristaltic action is generated as the transversely propagating field shapes the MRF/foam substrate in a corresponding way. Experimental results are discussed, an outline of on-going theoretical modeling is presented, and conclusions are provided.
Bimorph micro heat engines based on carbon nanotube freestanding films
Ikuno, Takashi; Fukano, Tatsuo; Higuchi, Kazuo; Takeda, Yasuhiko
2015-11-01
We have found that lightweight bimorph strips consisting of multiwalled carbon nanotube freestanding films (MWNT-FSFs) and Ni thin films exhibit a continuous bending-stretching motion on a hot plate even below the temperature of 100 °C in an environment at room temperature. In fact, the Ni/MWNT-FSFs exhibited this motion at a temperature difference of as small as 5 °C. The requirements of this motion have been qualitatively elucidated by a simulation based on a relaxation time approximation.
Swimming and peristaltic pumping between two plane parallel walls
Swimming at low Reynolds number in a fluid confined between two plane walls is studied for an infinite plane sheet located midway between the walls and distorted with a transverse propagating wave. It is shown that the flow pattern is closely related to that for peristaltic pumping. The hydrodynamic interaction between two flexible sheets swimming parallel in infinite space is related to the problem of peristaltic pumping in a planar channel with two wavy walls.
Electromechanical analysis of tapered piezoelectric bimorph at high electric field
Chattaraj, Nilanjan; Ganguli, Ranjan
2015-04-01
Piezoelectric bimorph laminar actuator of tapered width exhibits better performance for out-of-plane deflection compared to the rectangular surface area, while consuming equal surface area. This paper contains electromechanical analysis and modeling of a tapered width piezoelectric bimorph laminar actuator at high electric field in static state. The analysis is based on the second order constitutive equations of piezoelectric material, assuming small strain and large electric field to capture its behavior at high electric field. Analytical expressions are developed for block force, output strain energy, output energy density, input electrical energy, capacitance and energy efficiency at high electric field. The analytical expressions show that for fixed length, thickness, and surface area of the actuator, how the block force and output strain energy gets improved in a tapered surface actuator compared to a rectangular surface. Constant thickness, constant length and constant surface area of the actuator ensure constant mass, and constant electrical capacitance. We consider high electric field in both series and parallel electrical connection for the analysis. Part of the analytical results is validated with the experimental results, which are reported in earlier literature.
Design of a bimorph piezoelectric energy harvester for railway monitoring
Wireless sensor network is one of prospective methods for railway monitoring due to the long term operation and low maintenance performances. How to supply power to the wireless sensor nodes has drawn much attention recently. In railway monitoring, the idea of converting ambient vibration energy from vibration of railway track induced by passing trains to electric energy has made it a potential way for powering the wireless sensor nodes. In this paper, a bimorph cantilever piezoelectric energy harvester was designed based on a single degree of freedom model. Experimental test was also performed to validate the design. The first natural frequency of the bimorph piezoelectric energy harvester was decreased from 117.1 Hz to 65.2 Hz by adding 4 gram tip mass to the free end of the 8.6 gram energy harvester. In addition, the power generation of the piezoelectric energy harvester with 4 gram tip mass at resonant frequency was increased from 0.14 mW to 0.74 mW from 2.06 m/s2 base excitation compared to stand alone piezoelectric energy harvester without tip mass
Enhanced Magnetoelectric Coupling in Layered Structure of Piezoelectric Bimorph and Metallic Alloy
Petrov, V. M.; Bichurin, M. I.; Lavrentyeva, K. V.; Leontiev, V. S.
2016-08-01
We have investigated the enhanced magnetoelectric (ME) coupling in a layered structure of piezoelectric bimorph and magnetostrictive metallic alloy. The observed ME coefficient in the piezoelectric bimorph-based structure was found to be two times higher than in the traditional piezoelectric/magnetostrictive bilayer. The observed enhancement in ME coupling strength is related to equal signs of induced voltage in both lead zirconate titanate layers with opposite poling directions due to the flexural deformations. The piezoelectric bimorph-based structure has promising potential for sensor and technological applications.
Development and characterization of thermopneumatic peristaltic micropumps
In this paper, the development and characterization of thermopneumatic peristaltic micropumps are presented. Micropumps with three different designs are fabricated using soft lithography techniques. The equivalent circuit models of a thermopneumatic actuation cell are formulated. The analytical solutions for predicting the device transient behavior are also derived. The dynamical responses of the diaphragms are measured using an interferometer, and are in good agreement with the modeled results. Tiny drive circuits, which require only 5 V, are implemented for driving the pumps. The dimension of an integrated 3-chamber micropump system, which consists of a pump and a drive circuit, is 16 mm × 18 mm × 5.5 mm. The optimal operating conditions, such as actuation sequences, operating frequencies and duty ratios, are obtained. The maximum flow rate occurs at a driving frequency of 1.5 Hz with a duty ratio of 40% using a three-phase actuation sequence. A simplified pseudo thermo-fluid-structure-interaction (pT-FSI) model is also proposed to estimate the pumping characteristic. The model gives reasonable results under low operation frequency. Under zero backpressure, the maximum flow rates for the 3, 5 and 7-chamber devices are very close, whereas the devices with larger numbers of pumping chambers exhibit better pumping performance under higher backpressure
Development and characterization of thermopneumatic peristaltic micropumps
Yang, Yao-Joe; Liao, Hsin-Hung
2009-02-01
In this paper, the development and characterization of thermopneumatic peristaltic micropumps are presented. Micropumps with three different designs are fabricated using soft lithography techniques. The equivalent circuit models of a thermopneumatic actuation cell are formulated. The analytical solutions for predicting the device transient behavior are also derived. The dynamical responses of the diaphragms are measured using an interferometer, and are in good agreement with the modeled results. Tiny drive circuits, which require only 5 V, are implemented for driving the pumps. The dimension of an integrated 3-chamber micropump system, which consists of a pump and a drive circuit, is 16 mm × 18 mm × 5.5 mm. The optimal operating conditions, such as actuation sequences, operating frequencies and duty ratios, are obtained. The maximum flow rate occurs at a driving frequency of 1.5 Hz with a duty ratio of 40% using a three-phase actuation sequence. A simplified pseudo thermo-fluid-structure-interaction (pT-FSI) model is also proposed to estimate the pumping characteristic. The model gives reasonable results under low operation frequency. Under zero backpressure, the maximum flow rates for the 3, 5 and 7-chamber devices are very close, whereas the devices with larger numbers of pumping chambers exhibit better pumping performance under higher backpressure.
Optofluidic modulator based on peristaltic nematogen microflows
Cuennet, J. G.; Vasdekis, A. E.; de Sio, L.; Psaltis, D.
2011-04-01
Nematogens rotate by the application of external fields, thereby enabling optical modulation. This principle has had a profound impact on our daily lives through the plethora of liquid-crystal displays in use around us. However, the wider use of nematic liquid crystals, particularly in microdisplays and information processing, has been hampered by their slow response times. In nematogens, rotational and translational molecular motions are coupled, so flow is inevitably linked with optical modulation. This linkage motivated us to fuse microfluidics with anisotropic liquids and introduce an optofluidic modulator that exhibits a submillisecond (250 µs) symmetric response and can operate at frequencies up to 1 kHz. The modulator is based on peristaltic nematogen microflows realized in polydimethylsiloxane microfluidics. The latter simultaneously permits peristalsis by means of elastomeric deformation, nematogen alignment and rapid prototyping through cast-moulding. Together with large-scale, vertical integration and piezoelectric nanotechnologies, this optofluidic paradigm can enable high-density and three-dimensional architectures of fast modulators.
A vacuum-driven peristaltic micropump with valved actuation chambers
This paper presents a simple peristaltic micropump design incorporated with valved actuation chambers and propelled by a pulsed vacuum source. The vacuum-driven peristaltic micropump offers high pumping rates, low backflow, appreciable tolerance to air bubbles, and minimal destruction to fluid contents. The pumping device, fabricated by laser micromachining and plasma bonding of three polydimethylsiloxane (PDMS) layers, includes a pneumatic network, actuation membranes, and microfluidic channels. As the key to peristaltic motion, the sequential deflection of the elastic membranes is achieved by periodic pressure waveforms (negative) traveling through the pneumatic network, provided by a vacuum source regulated by an electromagnetic valve. This configuration eliminates the complicated control logic typically required in peristaltic motion. Importantly, the valved actuation chambers substantially reduce backflow and improve the pumping rates. In addition, the pneumatic network with negative pressure provides a means to effectively remove air bubbles present in the microflow through the gas-permeable PDMS membrane, which can be highly desired in handling complex fluidic samples. Experimental characterization of the micropump performance has been conducted by controlling the resistance of the pneumatic network, the number of normally closed valves, the vacuum pressure, and the frequency of pressure pulses. A maximal flow rate of 600 µL min−1 has been optimized at the pulsed vacuum frequency of 30 Hz with a vacuum pressure of 50 kPa, which is comparable to that of compressed air-actuated peristaltic micropumps
Dielectric elastomer peristaltic pump module with finite deformation
Mao, Guoyong; Huang, Xiaoqiang; Liu, Junjie; Li, Tiefeng; Qu, Shaoxing; Yang, Wei
2015-07-01
Inspired by various peristaltic structures existing in nature, several bionic peristaltic actuators have been developed. In this study, we propose a novel dielectric elastomer peristaltic pump consisting of short tubular modules, with the saline solution as the electrodes. We investigate the performance of this soft pump module under hydraulic pressure and voltage via experiments and an analytical model based on nonlinear field theory. It is observed that the individual pump module undergoes finite deformation and may experience electromechanical instability during operations. The driving pressure and displaced volume of the peristaltic pump module can be modulated by applied voltage. The efficiency of the pump module is enhanced by alternating current voltage, which can suppress the electromechanical pull-in instability. An analytical model is developed within the framework of the nonlinear field theory, and its predictive capacity is checked by experimental observations. The effects of the prestretch, aspect ratio, and voltage on the performance of the pump modules are characterized by the analytical model. This work can guide the designs of soft active peristaltic pumps in the field of artificial organs and industrial conveying systems.
An exceptional bimorph effect and a low quality factor from carbon nanotube-polymer composites
Microcantilever actuators made from carbon nanotube polymer are driven at very low pull-in voltages and the thermal bimorph effect reaches 325 μm at 26-110 deg. C, much greater than the values for existing devices
Bimorph actuators in thick SiO2 for photonic alignment
Wu, Kai; Peters, Tjitte-Jelte; Tichem, Marcel; Postma, Ferry; Prak, Albert; Wörhoff, Kerstin; Leinse, Arne
2016-03-01
This paper proposes and tests a design of electro-thermal bimorph actuators for alignment of flexible photonic waveguides fabricated in 16 µm thick SiO2. The actuators are for use in a novel alignment concept for multi-port photonic integrated circuits (PICs), in which the fine alignment is taken care of by positioning of suspended, mechanically flexible waveguide beams on one or more of the PICs. The design parameters of the bimorph actuator allow to tune both the initial relative position of the waveguide end-facets, and the motion range of the actuators. Bimorph actuators have been fabricated and characterized. The maximum out-of-plane deflection of the bimorph actuator (with 720 μm-long poly-Si) can reach 18:5 μm with 126:42mW, sufficient for the proposed application.
Analytical Modelling of a Plucked Piezoelectric Bimorph for Energy Harvesting
Pozzi, Michele
2012-01-01
Energy harvesting (EH) is a multidisciplinary research area, involving physics, materials science and engineering, with the objective of providing renewable sources of sufficient power to operate targeted low-power applications. Piezoelectric transducers are often used for vibrational, inertial and direct movement EH. One problem is that, due to the stiffness of the most common material (PZT) and typically useful sizes, intrinsic resonant frequencies are normally high, whereas the available power is often concentrated at low frequencies. The aim of the plucking technique of frequency up-conversion, also known as "pizzicato" excitation, is to bridge this frequency gap. In this paper, the technique is modelled analytically. The analytical model is developed starting from the Euler-Bernoulli beam equations modified for piezoelectric coupling. A system of differential equations and associated initial conditions are derived which describe the free vibration of a piezoelectric bimorph in the last part of the plucki...
Postprandial transduodenal bolus transport is regulated by complex peristaltic sequence
Huan Nam Nguyen; Ron Winograd; Gerson Ricardo Souza Domingues; Frank Lammert
2006-01-01
AIM: To study the relationship between the patterns of postprandial peristalsis and transduodenal bolus transport in healthy subjects.METHODS: Synchronous recording of chyme transport and peristaltic activity was performed during the fasting state and after administration of a test meal using a special catheter device with cascade configuration of impedance electrodes and solid-state pressure transducers. The catheter was placed into the duodenum,where the first channel was located in the first part of the duodenum and the last channel at the duodenojejunal junction. After identification of previously defined chyme transport patterns the associated peristaltic patterns were analyzed.RESULTS: The interdigestive phase 3 complex was reliably recorded with both techniques. Of 497 analyzed impedance bolus transport events, 110 (22%) were short-spanned propulsive, 307 (62%) long-spanned propulsive, 70 (14%)complex propulsive, and 10 (2%) retrograde transport.Short-spanned chyme transports were predominantly associated with stationary or propagated contractions propagated over short distance. Long-spanned and complex chyme transports were predominantly associated with propulsive peristaltic patterns, which were frequently complex and comprised multiple contractions. Propagated double wave contraction, propagated contraction with a clustered contraction, and propagated cluster of contractions have been identified to be an integralted part of a peristaltic sequence in human duodenum.CONCLUSION: Combined impedancometry andmanometry improves the analysis of the peristaltic patterns that are associated with postprandial transduodenal chyme transport. Postprandial transduodenal bolus transport is regulated by propulsive peristaltic patterns, which are frequently complex but well organized. This finding should be taken into consideration in the analysis of intestinal motility studies.
Heat Transfer Analysis for Peristaltic Mechanism in Variable Viscosity Fluid
T.Hayat; F.M.Abbasi; Awatif A.Hendi
2011-01-01
An analysis is carried out for a peristaltic flow of a third-order fluid with heat transfer and variable viscosity when no-slip condition does not hold. Perturbation solution is discussed and a comparative study between the cases of constant and variable viscosities is presented and analyzed.%@@ An analysis is carried out for a peristaltic flow of a third-order fluid with heat transfer and variable viscosity when no-slip condition does not hold.Perturbation solution is discussed and a comparative stuity between the cases of constant and variable viscosities is presented and analyzed.
Characterization of a next-generation piezo bimorph X-ray mirror for synchrotron beamlines
A next-generation bimorph mirror with piezos bonded to the side faces of a monolithic substrate was created. When replacing a first-generation bimorph mirror suffering from the junction effect, the new type of mirror significantly improved the size and shape of the reflected synchrotron X-ray beam. No evidence of the junction effect was observed even after eight months of continuous beamline usage. Piezo bimorph mirrors are versatile active optics used on many synchrotron beamlines. However, many bimorphs suffer from the ‘junction effect’: a periodic deformation of the optical surface which causes major aberrations to the reflected X-ray beam. This effect is linked to the construction of such mirrors, where piezo ceramics are glued directly below the thin optical substrate. In order to address this problem, a next-generation bimorph with piezos bonded to the side faces of a monolithic substrate was developed at Thales-SESO and optimized at Diamond Light Source. Using metrology feedback from the Diamond-NOM, the optical slope error was reduced to ∼0.5 µrad r.m.s. for a range of ellipses. To maximize usability, a novel holder was built to accommodate the substrate in any orientation. When replacing a first-generation bimorph on a synchrotron beamline, the new mirror significantly improved the size and shape of the reflected X-ray beam. Most importantly, there was no evidence of the junction effect even after eight months of continuous beamline usage. It is hoped that this new design will reinvigorate the use of active bimorph optics at synchrotron and free-electron laser facilities to manipulate and correct X-ray wavefronts
Peristaltic pump-based low range pressure sensor calibration system
Vinayakumar, K. B.; Naveen Kumar, G.; Nayak, M. M.; Dinesh, N. S.; Rajanna, K.
2015-11-01
Peristaltic pumps were normally used to pump liquids in several chemical and biological applications. In the present study, a peristaltic pump was used to pressurize the chamber (positive as well negative pressures) using atmospheric air. In the present paper, we discuss the development and performance study of an automatic pressurization system to calibrate low range (millibar) pressure sensors. The system includes a peristaltic pump, calibrated pressure sensor (master sensor), pressure chamber, and the control electronics. An in-house developed peristaltic pump was used to pressurize the chamber. A closed loop control system has been developed to detect and adjust the pressure leaks in the chamber. The complete system has been integrated into a portable product. The system performance has been studied for a step response and steady state errors. The system is portable, free from oil contaminants, and consumes less power compared to existing pressure calibration systems. The veracity of the system was verified by calibrating an unknown diaphragm based pressure sensor and the results obtained were satisfactory.
Peristaltic pump-based low range pressure sensor calibration system
Peristaltic pumps were normally used to pump liquids in several chemical and biological applications. In the present study, a peristaltic pump was used to pressurize the chamber (positive as well negative pressures) using atmospheric air. In the present paper, we discuss the development and performance study of an automatic pressurization system to calibrate low range (millibar) pressure sensors. The system includes a peristaltic pump, calibrated pressure sensor (master sensor), pressure chamber, and the control electronics. An in-house developed peristaltic pump was used to pressurize the chamber. A closed loop control system has been developed to detect and adjust the pressure leaks in the chamber. The complete system has been integrated into a portable product. The system performance has been studied for a step response and steady state errors. The system is portable, free from oil contaminants, and consumes less power compared to existing pressure calibration systems. The veracity of the system was verified by calibrating an unknown diaphragm based pressure sensor and the results obtained were satisfactory
Long Wavelength Peristaltic Transport of Non-Newton Fluids
Devanathan, R; Parvathamma, S.
1980-01-01
Solutions are obtained for the stream function and the pressure field for the flow of non-Newtonian fluids in a tube by long peristaltic waves of arbitrary shape. The axial velocity profiles and stress distributions on the wall are discussed for particular waves of some practical interest. The effect of non- Newtonian character of the fluid is examined.
Electroosmosis-modulated peristaltic transport in microfluidic channels
Bandopadhyay, Aditya; Tripathi, Dharmendra; Chakraborty, Suman
2016-05-01
We analyze the peristaltic motion of aqueous electrolytes altered by means of applied electric fields. Handling electrolytes in typical peristaltic channel material such as polyvinyl chloride and Teflon leads to the generation of a net surface charge on the channel walls, which attracts counter-ions and repels co-ions from the aqueous solution, thus leading to the formation of an electrical double layer—a region of net charges near the wall. We analyze the spatial distribution of pressure and wall shear stress for a continuous wave train and single pulse peristaltic wave in the presence of an electrical (electroosmotic) body force, which acts on the net charges in the electrical double layer. We then analyze the effect of the electroosmotic body force on the particle reflux as elucidated through the net displacement of neutrally buoyant particles in the flow as the peristaltic waves progress. The impact of combined electroosmosis and peristalsis on trapping of a fluid volume (e.g., bolus) inside the travelling wave is also discussed. The present analysis goes beyond the traditional analysis, which neglects the possibility of coupling the net pumping of fluids due to peristalsis and allows us to derive general expressions for the pressure drop and flow rate in order to set up a general framework for incorporating flow control and actuation by simultaneous peristalsis and application of electric fields to aqueous solutions. It is envisaged that the results presented here may act as a model for the design of lab-on-a-chip devices.
Peristaltic pump-based low range pressure sensor calibration system.
Vinayakumar, K B; Naveen Kumar, G; Nayak, M M; Dinesh, N S; Rajanna, K
2015-11-01
Peristaltic pumps were normally used to pump liquids in several chemical and biological applications. In the present study, a peristaltic pump was used to pressurize the chamber (positive as well negative pressures) using atmospheric air. In the present paper, we discuss the development and performance study of an automatic pressurization system to calibrate low range (millibar) pressure sensors. The system includes a peristaltic pump, calibrated pressure sensor (master sensor), pressure chamber, and the control electronics. An in-house developed peristaltic pump was used to pressurize the chamber. A closed loop control system has been developed to detect and adjust the pressure leaks in the chamber. The complete system has been integrated into a portable product. The system performance has been studied for a step response and steady state errors. The system is portable, free from oil contaminants, and consumes less power compared to existing pressure calibration systems. The veracity of the system was verified by calibrating an unknown diaphragm based pressure sensor and the results obtained were satisfactory. PMID:26628178
Peristaltic pump-based low range pressure sensor calibration system
Vinayakumar, K. B. [Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 5600012 (India); Department of Electronic Systems Engineering, Indian Institute of Science, Bangalore 5600012 (India); Naveen Kumar, G.; Rajanna, K., E-mail: kraj@isu.iisc.ernet.in, E-mail: krajanna2011@gmail.com [Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 5600012 (India); Nayak, M. M. [Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 5600012 (India); Dinesh, N. S. [Department of Electronic Systems Engineering, Indian Institute of Science, Bangalore 5600012 (India)
2015-11-15
Peristaltic pumps were normally used to pump liquids in several chemical and biological applications. In the present study, a peristaltic pump was used to pressurize the chamber (positive as well negative pressures) using atmospheric air. In the present paper, we discuss the development and performance study of an automatic pressurization system to calibrate low range (millibar) pressure sensors. The system includes a peristaltic pump, calibrated pressure sensor (master sensor), pressure chamber, and the control electronics. An in-house developed peristaltic pump was used to pressurize the chamber. A closed loop control system has been developed to detect and adjust the pressure leaks in the chamber. The complete system has been integrated into a portable product. The system performance has been studied for a step response and steady state errors. The system is portable, free from oil contaminants, and consumes less power compared to existing pressure calibration systems. The veracity of the system was verified by calibrating an unknown diaphragm based pressure sensor and the results obtained were satisfactory.
A Numerical Investigation of Peristaltic Waves in Circular Tubes
Xiao, Q.; Damodaran, M.
Peristaltic pumping is a process of fluid transport arising from the progressive waves, which travel along the walls of a flexible channel. It is a primary physiological transport mechanism that is inherent in many tubular organs of the human body such as the ureter, the gastro-intestinal tract, the urethra, and so on. Many studies exist in literature with the aim of understanding the characteristics of peristaltic flow under the assumption of low Reynolds number and infinitely long wavelength in a two-dimensional channel. However, peristaltic pumping is also the mechanism used in other industrial applications such as the blood pump for which the Reynolds number has a moderately high value. As studies concerning moderate to high Reynolds number flow in the circular tube are rare in literature, in the present study, the peristaltic flow of an incompressible fluid is numerically simulated using the finite volume method for solving the incompressible Navier-Stokes equations in primitive variable formulation by means of an infinite train of sinusoidal waves traveling along the wall of an axi-symmetric tube. The computational model presented in this work covers a wider range of Reynolds number (0.01-100), wave amplitude (0-0.8), and wavelength (0.01-0.4) than the those attempted in previous studies reported in literature and some new results pertaining to the distribution of velocity, pressure, wall shear stress for different peristaltic flow conditions characterizing flow at moderately higher Reynolds number have been obtained. The effect of the wave amplitude, wavelength, and Reynolds number on the "flow trapping" mechanism induced by peristalsis has also been investigated here for higher ranges of values of the parameters characterizing peristalsis.
PZT-5A4/PA and PZT-5A4/PDMS piezoelectric composite bimorphs
Disc type reinforced piezoelectric composite bimorphs with series connection were designed and the performance was investigated. The composite bimorphs (PZT/PA and PZT/PDMS (40/60 vol%)) were successfully fabricated by a compression molding and solution casting technique. The charge developed at an applied force of 150 N is 18150 pC (PZT/PA) and 2310 pC (PZT/PDMS), respectively. Electric force microscopy (EFM) is used to study the structural characterization and piezoelectric properties of the materials realized. A clear inverse piezoelectric effect was observed when the bimorphs were subjected to an electric field stepped up through 2, 6 and 10 V, indicating the net polarization direction of the different ferroelectric domains. The as-developed bimorphs have the basic structure of a sensor and actuator, and, since they do not use any bonding agent for bonding, they can provide a valuable alternative to the present bimorphs where bonding processes are required for their realization that can limit their application at high temperature. (paper)
无
2007-01-01
In order to describe the characteristics of piezoelectric bimorph, properties of lead zirconate titanate (LZT) film are studied by X-ray diffraction (XRD) and scanning eletron microscope (SEM). The ratio of PbTiO3/PbZrO3 in LZT is 53/47, which is around morphotropic phase boundary (MPB). LZT film is composed of cubic particles with the average size of 5 μm. Density of thin film is figured out through the datum measured in experiments. The displacement model used to analyze the driving ability of bimorph is set up, and the effect of elastic intermediate layer is taken into account. Piezoelectric coefficient of LZT film is worked out by using the displacement model. Experiments of driving ability show that deformation of bimorph free end does not increase with times of crystal growth processes and the maximum deformation is obtained after two times crystal growth processes. Finally, the ferroelectric property of the bimorph is investigated and coercive voltage of the bimorph is obtained.
Pneumatically Actuated Miniature Peristaltic Vacuum Pumps
Feldman, Sabrina; Feldman, Jason; Svehla, Danielle
2003-01-01
Pneumatically actuated miniature peristaltic vacuum pumps have been proposed for incorporation into advanced miniature versions of scientific instruments that depend on vacuum for proper operation. These pumps are expected to be capable of reaching vacuum-side pressures in the torr to millitorr range (from .133 down to .0.13 Pa). Vacuum pumps that operate in this range are often denoted roughing pumps. In comparison with previously available roughing pumps, these pumps are expected to be an order of magnitude less massive and less power-hungry. In addition, they would be extremely robust, and would operate with little or no maintenance and without need for oil or other lubricants. Portable mass spectrometers are typical examples of instruments that could incorporate the proposed pumps. In addition, the proposed pumps could be used as roughing pumps in general laboratory applications in which low pumping rates could be tolerated. The proposed pumps could be designed and fabricated in conventionally machined and micromachined versions. A typical micromachined version (see figure) would include a rigid glass, metal, or plastic substrate and two layers of silicone rubber. The bottom silicone layer would contain shallow pump channels covered by silicone arches that could be pushed down pneumatically to block the channels. The bottom silicone layer would be covered with a thin layer of material with very low gas permeability, and would be bonded to the substrate everywhere except in the channel areas. The top silicone layer would be attached to the bottom silicone layer and would contain pneumatic- actuation channels that would lie crosswise to the pump channels. This version is said to be micromachined because the two silicone layers containing the channels would be fabricated by casting silicone rubber on micromachined silicon molds. The pneumatic-actuation channels would be alternately connected to a compressed gas and (depending on pump design) either to atmospheric
Chakkalakkal Abdulla, S.M.; Kauppinen, L.J.; Dijkstra, M.; Boer, de M.J.; Berenschot, E.; Ridder, de R.M.; Krijnen, G.J.M.
2010-01-01
This paper presents the fabrication technology for a novel class of photonic devices. This technology integrates silicon 2-D photonic crystal (PhC) waveguides and electrostatically actuated bimorph cantilevers with tips that are self-aligned relative to the holes of the PhC. The bimorph cantilevers
Out-of-plane platforms with bi-directional thermal bimorph actuation for transducer applications
Conchouso, David
2015-04-01
This paper reports on the Buckled Cantilever Platform (BCP) that allows the manipulation of the out of plane structures through the adjustment of the pitch angle using thermal bimorph micro-Actuators. Due to the micro-fabrication process used, the bimorph actuators can be designed to move in both: Counter Clockwise (CCW) and Clockwise (CW) directions with a resolution of up to 110 μm/V, with smallest step in the range of nanometers. Thermal and electrical characterization of the thermal bimorph actuators showed low influence in the platforms temperature and low power consumption (< 35μW) mainly due to the natural isolation of the structure. Tip displacements larger than 500μm were achieved. The precise angle adjustment achieved through these mechanisms makes them optimal for a range of different MEMS applications, like optical benches and low frequency sweeping sensors and antennas. © 2015 IEEE.
Determination of maximum power transfer conditions of bimorph piezoelectric energy harvesters
Ahmad, Mahmoud Al
2012-07-23
In this paper, a method to find the maximum power transfer conditions in bimorph piezoelectric-based harvesters is proposed. Explicitly, we derive a closed form expression that relates the load resistance to the mechanical parameters describing the bimorph based on the electromechanical, single degree of freedom, analogy. Further, by taking into account the intrinsic capacitance of the piezoelectric harvester, a more descriptive expression of the resonant frequency in piezoelectric bimorphs was derived. In interest of impartiality, we apply the proposed philosophy on previously published experimental results and compare it with other reported hypotheses. It was found that the proposed method was able to predict the actual optimum load resistance more accurately than other methods reported in the literature. © 2012 American Institute of Physics.
Competition between the Thermal Gradient and the Bimorph Effect in Locally Heated MEMS Actuators
Jeppesen, Claus; Mølhave, Kristian; Kristensen, Anders
2009-01-01
We have investigated the influence of thermal gradient effects in inhomogeneously heated MEMS/NEMS. The actuation perturbations caused by thermal gradients have been studied through static optothermal actuation experiments of a bi-material polymer based cantilever and supported by finite element...... modeling. As a result, bidirectional bending has been experimentally observed and interpreted as the competition between bimorph and thermal gradient effects. The competition has illustrated the importance of including the thermal gradient effect in the behavior analysis of bimorph driven MEMS/NEMS devices....
Xu, Ruichao; Lei, Anders; Dahl-Petersen, Christian;
2012-01-01
We describe the fabrication and characterization of a significantly improved version of a microelectromechanical system-based PZT/PZT thick film bimorph vibration energy harvester with an integrated silicon proof mass; the harvester is fabricated in a fully monolithic process. The main advantage of...... bimorph vibration energy harvesters is that strain energy is not lost in mechanical support materials since only Pb(ZrxTi1-x)O3 (PZT) is strained; as a result, the effective system coupling coefficient is increased, and thus a potential for significantly higher output power is released. In addition, when...
Magnetic cantilever actuator with sharpened magnetic thin film ellipses
Huang, Chen-Yu; Ger, Tzong-Rong; Lai, Mei-Feng; Chen, We-Yun; Huang, Hao-Ting; Chen, Jiann-Yeu; Wang, Pei-Jen; Wei, Zung-Hang
2015-05-01
A SiO2 cantilever covered by elliptical magnetic thin films was designed as an actuator. Under magnetic field, the elliptical magnetic film with sharp ends would exhibit single-domain structures and generate torque to push or pull the two arms of the cantilever. The cantilever could then stretch or compress and the displacement could be controlled by adjusting the magnitude and direction of the external magnetic field. The combination between micromagnetism of patterned films and actuator was successfully demonstrated. The magnetic actuator can be applied for future application in the biological field and would be valuable for microelectromechanical systems (MEMS).
Vibration analysis of magnetostrictive thin-film composite cantilever actuator
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.
PDMS Based Thermopnuematic Peristaltic Micropump for Microfluidic Systems
A thermopnuematic peristaltic micropump for controlling micro litters of fluid was designed and fabricated from multi-stack PDMS structure on glass substrate. Pump structure consists of inlet and outlet, microchannel, three thermopneumatic actuation chambers, and three heaters. In microchannel, fluid is controlled and pumped by peristaltic motion of actuation diaphragm. Actuation diaphragm can bend up and down by exploiting air expansion that is induced by increasing heater temperature. The micropump characteristics were measured as a function of applied voltage and frequency. The flow rate was determined by periodically recording the motion of fluid at Nanoport output and computing flow volume from height difference between consecutive records. From the experiment, an optimum flow rate of 0.82 μl/min is obtained under 14 V three-phase input voltages at 0.033 Hz operating frequency
Effects of Magnetic Field and an Endoscope on Peristaltic Motion
V. P. Rathod
2011-01-01
Full Text Available The Problem of peristaltic transport of a magnetic fluid with variable viscosity through the gap between coaxial tubes where the outer tube is nonuniform with sinusoidal wave traveling down its wall and the inner tube is rigid. The relation between the pressure gradient and friction force on the inner and outer tubes is obtained in terms of magnetic and viscosity parameter. The numerical solutions of pressure gradient, outer friction and inner friction force, and flow rate are shown graphically.
Peristaltic particle transport using the Lattice Boltzmann method
Connington, Kevin William [Los Alamos National Laboratory; Kang, Qinjun [Los Alamos National Laboratory; Viswanathan, Hari S [Los Alamos National Laboratory; Abdel-fattah, Amr [Los Alamos National Laboratory; Chen, Shiyi [JOHNS HOPKINS UNIV.
2009-01-01
Peristaltic transport refers to a class of internal fluid flows where the periodic deformation of flexible containing walls elicits a non-negligible fluid motion. It is a mechanism used to transport fluid and immersed solid particles in a tube or channel when it is ineffective or impossible to impose a favorable pressure gradient or desirous to avoid contact between the transported mixture and mechanical moving parts. Peristaltic transport occurs in many physiological situations and has myriad industrial applications. We focus our study on the peristaltic transport of a macroscopic particle in a two-dimensional channel using the lattice Boltzmann method. We systematically investigate the effect of variation of the relevant dimensionless parameters of the system on the particle transport. We find, among other results, a case where an increase in Reynolds number can actually lead to a slight increase in particle transport, and a case where, as the wall deformation increases, the motion of the particle becomes non-negative only. We examine the particle behavior when the system exhibits the peculiar phenomenon of fluid trapping. Under these circumstances, the particle may itself become trapped where it is subsequently transported at the wave speed, which is the maximum possible transport in the absence of a favorable pressure gradient. Finally, we analyze how the particle presence affects stress, pressure, and dissipation in the fluid in hopes of determining preferred working conditions for peristaltic transport of shear-sensitive particles. We find that the levels of shear stress are most hazardous near the throat of the channel. We advise that shear-sensitive particles should be transported under conditions where trapping occurs as the particle is typically situated in a region of innocuous shear stress levels.
Augmentation of peristaltic microflows through electro-osmotic mechanisms
The present work aims to theoretically establish that the employment of an axial electric field can substantially augment the rate of microfluidic transport occurring in peristaltic microtubes. For theoretical analysis, shape evolution of the tube is taken to be arbitrary, except for the fact that the characteristic wavelength is assumed to be significantly greater than the average radius of cross section. First, expressions for the velocity profile within the tube are derived and are subsequently utilized to obtain variations in the net flow rate across the same, as a function of the pertinent system parameters. Subsequently, the modes of interaction between the electro-osmotic and peristaltic mechanisms are established through the variations in the time-averaged flow rates for zero pressure rise and the pressure rise for zero time-averaged flow rates, as expressed in terms of the occlusion number, characteristic electro-osmotic velocity and the peristaltic wave speed. From the simulation predictions, it is suggested that a judicious combination of peristalsis and an axial electrokinetic body force can drastically enhance the time-averaged flow rate, provided that the occlusion number is relatively small
Unifying synchronous tree-adjoining grammars and tree transducers via bimorphisms.
Shieber, Stuart
2006-01-01
We place synchronous tree-adjoining grammars and tree transducers in the single overarching framework of bimorphisms, continuing the unification of synchronous grammars and tree transducers initiated by Shieber (2004). Along the way, we present a new definition of the tree-adjoining grammar derivation relation based on a novel direct inter-reduction of TAG and monadic macro tree transducers.
Screen printed PZT/PZT thick film bimorph MEMS cantilever device for vibration energy harvesting
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...
Optimization of piezoelectric bimorph actuators with active damping for static and dynamic loads
Donoso, Alberto; Sigmund, Ole
2009-01-01
The paper considers optimal design problems in the context of active damping. More specifically, we are interested in controlling the tip-deflection of a cantilever beam subjected to static and time-harmonic loading on its free extreme. First, the thickness profile of a piezoelectric bimorph...
Thermal stability test and analysis of a 20-actuator bimorph deformable mirror
Ning Yu; Zhou Hong; Yu Hao; Rao Chang-Hui; Jiang Wen-Han
2009-01-01
One of the important characteristic of adaptive mirrors is the thermal stability of surface flatness. In this paper, the thermal stability from 13℃ to 25℃ of a 20-actuator bimorph deformable mirror is tested by a Shack-Hartmann wavefront sensor. Experimental results show that, the surface P-V of bimorph increases nearly linearly with ambient temperature. The ratio is 0.11 μm/℃ and the major component of surface displacement is defocused, compared with which, astigmatism, coma and spherical aberration contribute very small. Besides, a finite element model is built up to analyse the influence of thickness, thermal expansion coefficient and Young's modulus of materials on thermal stability. Calculated results show that bimorph has the best thermal stability when the materials have the same thermal expansion coefficient. And when the thickness ratio of glass to PZT is 3 and Young's modulus ratio is approximately 0.4, the surface instability behaviour of the bimorph manifests itself most severely.
The modern drive towards mobility and wireless devices is motivating intensive research in energy harvesting technologies. To reduce the battery burden on people, we propose the adoption of a frequency up-conversion strategy for a new piezoelectric wearable energy harvester. Frequency up-conversion increases efficiency because the piezoelectric devices are permitted to vibrate at resonance even if the input excitation occurs at much lower frequency. Mechanical plucking-based frequency up-conversion is obtained by deflecting the piezoelectric bimorph via a plectrum, then rapidly releasing it so that it can vibrate unhindered; during the following oscillatory cycles, part of the mechanical energy is converted into electrical energy. In order to guide the design of such a harvester, we have modelled with finite element methods the response and power generation of a piezoelectric bimorph while it is plucked. The model permits the analysis of the effects of the speed of deflection as well as the prediction of the energy produced and its dependence on the electrical load. An experimental rig has been set up to observe the response of the bimorph in the harvester. A PZT-5H bimorph was used for the experiments. Measurements of tip velocity, voltage output and energy dissipated across a resistor are reported. Comparisons of the experimental results with the model predictions are very successful and prove the validity of the model
Screen printed PZT/PZT thick film bimorph MEMS cantilever device for vibration energy harvesting
Xu, R.; Lei, A.; Christiansen, T. L.; Hansen, K.; Guizzetti, M.; Birkelund, Karen; Thomsen, E. V.; Hansen, Ole
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 pr...
Analysis of resonance frequency and pull-in voltages of curled micro-bimorph cantilevers
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
Fu, Ji; Li, Faxin
2015-10-01
We proposed a finger-like hardness tester based on the electromechanical impedance of a piezoelectric bimorph cantilever. A Vickers indenter was fabricated to the free end of the bimorph to contact the sample. The contact force was monitored by a strain gauge and the contact area was obtained by tracking the bimorph's resonance frequency. The bimorph-sample contact system was modeled by the electromechanical equivalent circuit method. Verification experiments on standard hardness samples were conducted and the measured hardness values agreed well with those given by a conventional Vickers hardness tester. Further hardness measurement on a gear wheel showed that the proposed hardness tester is very adaptive and can be used for inner surface testing or in situ testing, where other hardness testers may not be applicable. The proposed hardness tester can be regarded as an improved ultrasonic hardness tester.
Modeling and Tuning for Vibration Energy Harvesting using a Piezoelectric Bimorph
Cao, Yongqing
With the development of wireless sensors and other devices, the need for continuous power supply with high reliability is growing ever more. The traditional battery power supply has the disadvantage of limited duration of continuous power supply capability so that replacement for new batteries has to be done regularly. This can be quite inconvenient and sometimes quite difficult especially when the sensors are located in places not easily accessible such as the inside of a machine or wild field. This situation stimulates the development of renewable power supply which can harvest energy from the environment. The use of piezoelectric materials to converting environment vibration to electrical energy is one of the alternatives of which a broad range of research has been done by many researchers, focusing on different issues. The improvement of efficiency is one of the most important issues in vibration based energy harvesting. For this purpose different methods are devised and more accurate modeling of coupled piezoelectric mechanical systems is investigated. In the current paper, the research is focused on improving voltage generation of a piezoelectric bimorph on a vibration beam, as well as the analytical modeling of the same system. Also an initial study is conducted on the characteristics of the vibration of Zinc oxide (ZnO) nanowire, which is a promising material for its coupled semiconducting and piezoelectric properties. The effect on the voltage generation by different placement of the piezoelectric bimorph on the vibrating beam is investigated. The relation between the voltage output and the curvature is derived which is used to explain the effect of placement on voltage generation. The effect of adding a lumped mass on the modal frequencies of the beam and on the curvature distribution is investigated. The increased voltage output from the piezoelectric bimorph by using appropriately selected mass is proved analytically and also verified by experiment. For
In vivo organ specific drug delivery with implantable peristaltic pumps.
Speed, Joshua S; Hyndman, Kelly A
2016-01-01
Classic methods for delivery of agents to specific organs are technically challenging and causes superfluous stress. The current study describes a method using programmable, implantable peristaltic pumps to chronically deliver drugs in vivo, while allowing animals to remain undisturbed for accurate physiological measurements. In this study, two protocols were used to demonstrate accurate drug delivery to the renal medulla. First, the vasopressin receptor-2 agonist, dDAVP, was delivered to the renal medulla resulting in a significant increase in water retention, urine osmolality and aquaporin-2 expression and phosphorylation. Second, in a separate group of rats, the histone deacetylase (HDAC) inhibitor, MS275, was delivered to the renal medulla. HDAC inhibition resulted in a significant increase in histone H3-acetylation, the hallmark for histone deacetylase inhibition. However, this was confined to the medulla, as the histone H3-acetylation was similar in the cortex of vehicle and MS275 infused rats, suggesting targeted drug delivery without systemic spillover. Thus, implantable, peristaltic pumps provide a number of benefits compared to externalized chronic catheters and confer specific delivery to target organs. PMID:27185292
Comment on 'Modeling and analysis of a bimorph piezoelectric cantilever beam for voltage generation'
In a recent paper, Ajitsaria et al (2007 Smart Mater. Struct. 16 447–54) presented a mathematical formulation for the modeling and analysis of a bimorph piezoelectric cantilever beam for voltage generation. Their motivation was the recent increasing trend in using the piezoelectric effect to harvest electrical energy from ambient vibrations. This comment addresses the modeling errors and numerous undefined and missing terms in the mentioned work. (comment)
Çilingir, Halime Didem; Cilingir, Halime Didem
2008-01-01
This thesis addresses the Ionic Polymer Metal Composite (IPMC) actuators and two “equivalent” materials parameters for their design and performance assessments: electromechanical coupling coefficient and elastic modulus. The “equivalent” parameters not being material constants are derived from equivalent bimorph beam model. The Nafion membrane based IPMC actuator strips of several thicknesses are manufactured by electrochemical platinization method. The effect of the thickness and operating ...
A low frequency piezoelectric power harvester using a spiral-shaped bimorph
HU Yuantai; HU Hongping; YANG Jiashi
2006-01-01
We propose a spiral-shaped piezoelectric bimorph power harvester operating with coupled flexural and extensional vibration modes for applications to low frequency energy sources.A theoretical analysis is performed and the computational results show that the spiral structure has relatively low operating frequency compared to beam power harvesters of the same size.It is found that to optimize the performance of a piezoelectric spiral-shaped harvester careful design is needed.
Yuantai Hu; Ting Hu; Qing Jiang
2007-01-01
The authors analyze a piezoelectric energy harvester as an electro-mechanically coupled system. The energy harvester consists of a piezoelectric bimorph with a concentrated mass attached at one end, called the harvesting structure, an electric circuit for energy storage,and a rectifier that converts the AC output of the harvesting structure into a DC input for the storage circuit. The piezoelectric bimorph is assumed to be driven into flexural vibration by an ambient acoustic source to convert the mechanical energies into electric energies. The analysis indicates that the performance of this harvester, measured by the power density, is characterized by three important non-dimensional parameters, I.e., the non-dimensional inductance of the storage circuit, the non-dimensional aspect ratio (length/thickness) and the non-dimensional end mass of the harvesting structure. The numerical results show that: (1) the power density can be optimized by varying the non-dimensional inductance for each fixed non-dimensional aspect ratio with a fixed non-dimensional end mass; and (2) for a fixed non-dimensional inductance, the power density is maximized if the non-dimensional aspect ratio and the non-dimensional end mass are so chosen that the harvesting structure, consisting of both the piezoelectric bimorph and the end mass attached, resonates at the frequency of the ambient acoustic source.
Peristaltic Transport of a Couple Stress Fluid : Some Physiological Applications
Maiti, S
2010-01-01
The present paper deals with a theoretical investigation of the peristaltic transport of a couple stress fluid in a porous channel. The study is motivated towards the physiological flow of blood in the micro-circulatory system, by taking account of the particle size effect. The velocity, pressure gradient, stream function and frictional force of blood are investigated, when the Reynolds number is small and the wavelength is large, by using appropriate analytical and numerical methods. Effects of different physical parameters reflecting porosity, Darcy number, couple stress parameter as well as amplitude ratio on velocity profiles, pumping action and frictional force, streamlines pattern and trapping of blood are studied with particular emphasis. The computational results are presented in graphical form. The results are found to be in good agreement with those of Shapiro et. al \\cite{r25} that was carried out for a non-porous channel in the absence of couple stress effect. The present study puts forward an imp...
Development of Stepper motor based Two DOF Robotic Arm Transferring Liquid using Peristaltic Pump
Padma Thiagarajan; Sudha Ramasamy; Karthikesh.R; Manikandan.P
2013-01-01
The aim of this work is to transfer liquid contents from one micro cell to another using two stepper motors and a peristaltic pump. There are two objectives here. One is to develop a low cost roboticarm using stepper motors. The second objective is the control and calibration of the peristaltic pump. All parts are controlled and operated by their respective microcontrollers. Fulfillment of both the objectives leads to an integrated system to transfer liquids from one cell to another. The end ...
Dynamic simulation of a peristaltic micropump considering coupled fluid flow and structural motion
Lin, Qiao; Yang, Bozhi; Xie, Jun; Tai, Yu-Chong
2007-01-01
This paper presents lumped-parameter simulation of dynamic characteristics of peristaltic micropumps. The pump consists of three pumping cells connected in series, each of which is equipped with a compliant diaphragm that is electrostatically actuated in a peristaltic sequence to mobilize the fluid. Diaphragm motion in each pumping cell is first represented by an effective spring subjected to hydrodynamic and electrostatic forces. These cell representations are then used to construct a system...
Peristaltic Flow of Phan-Thien-Tanner Fluid in an Asymmetric Channel with Porous Medium
Kuppalapalle Vajravelu; S.Sreenadh; Lakshminarayana, P; G. Sucharitha; Rashidi, M. M.
2016-01-01
This paper deals with peristaltic transport of Phan-Thien-Tanner fluid in an asymmetric channel induced by sinusoidal peristaltic waves traveling down the flexible walls of the channel. The flow is investigated in a wave frame of reference moving with the velocity of the waveby using the long wavelength and low Reynolds number approximations.The nonlinear governing equations are solved employing a perturbation method by choosing as the perturbation parameter. The expressions for velocity, s...
Sreenivasulu, Gollapudi; Qu, Peng; Petrov, Vladimir; Qu, Hongwei; Srinivasan, Gopalan
2016-01-01
Multiferroic composites with ferromagnetic and ferroelectric phases have been studied in recent years for use as sensors of AC and DC magnetic fields. Their operation is based on magneto-electric (ME) coupling between the electric and magnetic subsystems and is mediated by mechanical strain. Such sensors for AC magnetic fields require a bias magnetic field to achieve pT-sensitivity. Novel magnetic sensors with a permanent magnet proof mass, either on a ferroelectric bimorph or a ferromagnetic-ferroelectric composite, are discussed. In both types, the interaction between the applied AC magnetic field and remnant magnetization of the magnet results in a mechanical strain and a voltage response in the ferroelectric. Our studies have been performed on sensors with a Nd-Fe-B permanent magnet proof mass on (i) a bimorph of oppositely-poled lead zirconate titanate (PZT) platelets and (ii) a layered multiferroic composite of PZT-Metglas-Ni. The sensors have been characterized in terms of sensitivity and equivalent magnetic noise N. Noise N in both type of sensors is on the order of 200 pT/√Hz at 1 Hz, a factor of 10 improvement compared to multiferroic sensors without a proof mass. When the AC magnetic field is applied at the bending resonance for the bimorph, the measured N ≈ 700 pT/√Hz. We discuss models based on magneto-electro-mechanical coupling at low frequency and bending resonance in the sensors and theoretical estimates of ME voltage coefficients are in very good agreement with the data. PMID:26907290
Sreenivasulu, Gollapudi; Qu, Peng; Petrov, Vladimir; Qu, Hongwei; Srinivasan, Gopalan
2016-01-01
Multiferroic composites with ferromagnetic and ferroelectric phases have been studied in recent years for use as sensors of AC and DC magnetic fields. Their operation is based on magneto-electric (ME) coupling between the electric and magnetic subsystems and is mediated by mechanical strain. Such sensors for AC magnetic fields require a bias magnetic field to achieve pT-sensitivity. Novel magnetic sensors with a permanent magnet proof mass, either on a ferroelectric bimorph or a ferromagnetic-ferroelectric composite, are discussed. In both types, the interaction between the applied AC magnetic field and remnant magnetization of the magnet results in a mechanical strain and a voltage response in the ferroelectric. Our studies have been performed on sensors with a Nd-Fe-B permanent magnet proof mass on (i) a bimorph of oppositely-poled lead zirconate titanate (PZT) platelets and (ii) a layered multiferroic composite of PZT-Metglas-Ni. The sensors have been characterized in terms of sensitivity and equivalent magnetic noise N. Noise N in both type of sensors is on the order of 200 pT/√Hz at 1 Hz, a factor of 10 improvement compared to multiferroic sensors without a proof mass. When the AC magnetic field is applied at the bending resonance for the bimorph, the measured N ≈ 700 pT/√Hz. We discuss models based on magneto-electro-mechanical coupling at low frequency and bending resonance in the sensors and theoretical estimates of ME voltage coefficients are in very good agreement with the data. PMID:26907290
Largest in the world bimorph deformable mirror for high-power laser beam correction
Kudryashov, Alexis; Samarkin, Vadim; Aleksandrov, Alex; Borsoni, Giles; Jitsuno, Takahisa; Romanov, Pavel; Sheldakova, Julia
2016-03-01
The deformable mirror with the size of 410x468 mm controlled by the bimorph piezoceramic plates and multilayer piezoceramic stacks was developed. The results of the measurements of the response functions of all the actuators and of the surface shape of the deformable mirror are presented in this paper. The study of the mirror with a Fizeau interferometer and a Shack-Hartmann wavefront sensor has shown that it was possible to improve the flatness of the surface down to a residual roughness of 0.033 μm (RMS). The possibility of correction of the aberrations in high power lasers was numerically demonstrated.
Screen printed PZT/PZT thick film bimorph MEMS cantilever device for vibration energy harvesting
Xu, R.; Lei, A.; 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....
Electrothermally-Actuated Micromirrors with Bimorph Actuators—Bending-Type and Torsion-Type
Cheng-Hua Tsai
2015-06-01
Full Text Available Three different electrothermally-actuated MEMS micromirrors with Cr/Au-Si bimorph actuators are proposed. The devices are fabricated with the SOIMUMPs process developed by MEMSCAP, Inc. (Durham, NC, USA. A silicon-on-insulator MEMS process has been employed for the fabrication of these micromirrors. Electrothermal actuation has achieved a large angular movement in the micromirrors. Application of an external electric current 0.04 A to the bending-type, restricted-torsion-type, and free-torsion-type mirrors achieved rotation angles of 1.69°, 3.28°, and 3.64°, respectively.
A peristaltic micropump using traveling waves on a polymer membrane
We demonstrate a peristaltic micropump that utilizes traveling waves on polymer membranes to transport liquids. This micropump requires no valves and, more importantly, the traveling waves can be generated by a single actuator. These features enable the design of simple, compact devices. This micropump has a hydraulic displacement amplification mechanism (HDAM) that encapsulates an incompressible fluid with flexible polymer membranes made of polydimethyl siloxane. A microchannel is attached to the top side of the HDAM. We used a cantilever-type piezoelectric actuator to oscillate the flexible membrane at the bottom of the HDAM, while the top-side membrane drives the liquid in the channel. This format enables rectangular parallelepiped micropumps as compact as 36 mm long, 10 mm wide and several millimeters high, depending on the channel height. Experiments using the fabricated micropumps equipped with microchannels of various heights revealed that the flow rate was dependent on the ratio of the amplitude of the traveling waves to the height of the fluidic channel. The manufactured micropump could successfully generate a maximum flow rate of 1.5 ml min−1 at 180 mW. (paper)
Peristaltic motion of third grade fluid in curved channel
S.HINA; M.MUSTAFA; T.HAYAT; F.E.ALSAADI
2014-01-01
Analysis is performed to study the slip effects on the peristaltic flow of non-Newtonian fluid in a curved channel with wall properties. The resulting nonlinear partial differential equations are transformed to a single ordinary differential equation in a stream function by using the assumptions of long wavelength and low Reynolds number. This differential equation is solved numerically by employing the built-in routine for solving nonlinear boundary value problems (BVPs) through the software Mathematica. In addition, the analytic solutions for small Deborah number are computed with a regular perturbation technique. It is noticed that the symmetry of bolus is destroyed in a curved channel. An intensification in the slip effect results in a larger magnitude of axial velocity. Further, the size and circulation of the trapped boluses increase with an increase in the slip parameter. Different from the case of planar channel, the axial velocity profiles are tilted towards the lower part of the channel. A comparative study between analytic and numerical solutions shows excellent agreement.
We describe the fabrication and characterization of a significantly improved version of a microelectromechanical system-based PZT/PZT thick film bimorph vibration energy harvester with an integrated silicon proof mass; the harvester is fabricated in a fully monolithic process. The main advantage of bimorph vibration energy harvesters is that strain energy is not lost in mechanical support materials since only Pb(ZrxTi1-x)O3 (PZT) is strained; as a result, the effective system coupling coefficient is increased, and thus a potential for significantly higher output power is released. In addition, when the two layers are connected in series, the output voltage is increased, and as a result the relative power loss in the necessary rectifying circuit is reduced. We describe an improved process scheme for the energy harvester, which resulted in a robust fabrication process with a record high fabrication yield of 98%. The robust fabrication process allowed a high pressure treatment of the screen printed PZT thick films prior to sintering. The high pressure treatment improved the PZT thick film performance and increased the harvester power output to 37.1 μW at 1 g root mean square acceleration. We also characterize the harvester performance when only one of the PZT layers is used while the other is left open or short circuit. (paper)
Beam cleanup of a 532-nm pulsed solid-state laser using a bimorph mirror
Xiang Lei; Bing Xu; Ping Yang; Lizhi Dong; Wenjin Liu; Hu Yan
2012-01-01
A successful beam cleanup of a 5-mJ/200-μs pulsed solid-state laser system operating at 532-nm wavelength is demonstrated. In this beam cleanup system, a wave-front sensor-less adaptive optics (AO) system is set up with a 20-element bimorph mirror (BM), a high-voltage amplifier, a charge-coupled device camera, and a control software implementing the stochastic parallel gradient descent (SPGD) algorithm. The brightness of the laser focal spot is improved because the wave-front distortions have been compensated. The performance of this system is presented and the experimental results are analyzed.%A successful beam cleanup of a 5-mJ/200-μs pulsed solid-state laser system operating at 532-nm wavelength is demonstrated.In this beam cleanup system,a wave-front sensor-less adaptive optics (AO) system is set up with a 20-element bimorph mirror (BM),a high-voltage amplifier,a charge-coupled device camera,and a control software implementing the stochastic parallel gradient descent (SPGD) algorithm.The brightness of the laser focal spot is improved because the wave-front distortions have been compensated.The performance of this system is presented and the experimental results are analyzed.
An analytical solution for the magneto-electro-elastic bimorph beam forced vibrations problem
Based on the Timoshenko beam theory and on the assumption that the electric and magnetic fields can be treated as steady, since elastic waves propagate very slowly with respect to electromagnetic ones, a general analytical solution for the transient analysis of a magneto-electro-elastic bimorph beam is obtained. General magneto-electric boundary conditions can be applied on the top and bottom surfaces of the beam, allowing us to study the response of the bilayer structure to electromagnetic stimuli. The model reveals that the magneto-electric loads enter the solution as an equivalent external bending moment per unit length and as time-dependent mechanical boundary conditions through the definition of the bending moment. Moreover, the influences of the electro-mechanic, magneto-mechanic and electromagnetic coupling on the stiffness of the bimorph stem from the computation of the beam equivalent stiffness constants. Free and forced vibration analyses of both multiphase and laminated magneto-electro-elastic composite beams are carried out to check the effectiveness and reliability of the proposed analytic solution
Distributed and lumped element models for a bimorph-actuated micromirror
A procedure to model electrothermally actuated devices is developed and demonstrated using a 1D scanning micromirror. The micromirror is actuated by thermal bimorphs and an embedded platinum (Pt) resistor is used for generating Joule heating. Electrothermal, thermal and thermomechanical models are developed and integrated to generate a compact electrothermomechanical model. The electrothermal model relates the thermal power generated in the device to the applied voltage. The thermomechanical model evaluates the mirror rotation angle. The thermal model is developed by drawing analogy between heat flow in the device and current flow through an electrical transmission line. It provides the temperature of the embedded heater and the bimorph actuators. The heat loss coefficient to the surrounding atmosphere is obtained from finite element (FE) simulations. The distributed thermal resistances are represented by an equivalent circuit model with a few elements. A simplification of the circuit model is proposed when small length scales are involved. Rotation angle per unit power input predicted by the circuit model has an error of less than 8% compared to experimental results.
Walton, John P.; Coutu, Ronald A.; Starman, LaVern
2015-02-01
There are numerous applications for micromirror arrays seen in our everyday lives. From flat screen televisions and computer monitors, found in nearly every home and office, to advanced military weapon systems and space vehicles, each application bringing with it a unique set of requirements. The microelectromechanical systems (MEMS) industry has researched many ways micromirror actuation can be accomplished and the different constraints on performance each design brings with it. This paper investigates a new "zipper" approach to electrostatically driven micromirrors with the intent of improving duel plane beam steering by coupling large deflection angles, over 30°, and a fast switching speed. To accomplish this, an extreme initial deflection is needed which can be reached using high stress bimorph beams. Currently this requires long beams and high voltage for the electrostatic pull in or slower electrothermal switching. The idea for this "zipper" approach is to stack multiple beams of a much shorter length and allow for the deflection of each beam to be added together in order to reach the required initial deflection height. This design requires much less pull-in voltage because the pull-in of one short beam will in turn reduce the height of the all subsequent beams, making it much easier to actuate. Using modeling and simulation software to characterize operations characteristics, different bimorph cantilever beam configurations are explored in order to optimize the design. These simulations show that this new "zipper" approach increases initial deflection as additional beams are added to the assembly without increasing the actuation voltage.
An analytical solution for the magneto-electro-elastic bimorph beam forced vibrations problem
Milazzo, A.; Orlando, C.; Alaimo, A.
2009-08-01
Based on the Timoshenko beam theory and on the assumption that the electric and magnetic fields can be treated as steady, since elastic waves propagate very slowly with respect to electromagnetic ones, a general analytical solution for the transient analysis of a magneto-electro-elastic bimorph beam is obtained. General magneto-electric boundary conditions can be applied on the top and bottom surfaces of the beam, allowing us to study the response of the bilayer structure to electromagnetic stimuli. The model reveals that the magneto-electric loads enter the solution as an equivalent external bending moment per unit length and as time-dependent mechanical boundary conditions through the definition of the bending moment. Moreover, the influences of the electro-mechanic, magneto-mechanic and electromagnetic coupling on the stiffness of the bimorph stem from the computation of the beam equivalent stiffness constants. Free and forced vibration analyses of both multiphase and laminated magneto-electro-elastic composite beams are carried out to check the effectiveness and reliability of the proposed analytic solution.
Out-of-Plane Translational PZT Bimorph Actuator with Archimedes’ Spiral Actuating Tethers
Yang, Chenye; Liu, Sanwei; Livermore, Carol
2015-12-01
The design, finite element analysis (FEA), and experimental characterization of a MEMS out-of-plane (vertical) translational lead-zirconate-titanate (PZT) bimorph actuator supported on Archimedes’ spiral tethers are presented. Two types of bimorph actuators with different electrode patterns (with spiral tethers half actuated or fully actuated) are designed and fabricated. Both designs are fabricated by commercial processes and are compatible with integration into more complex MEMS systems. Finite element analysis (FEA) was used to analyze and predict the displacements of both types of actuators. The deflections of both fully- actuated and half-actuated devices were measured experimentally to validate the design. At an applied voltage of 110V, the out-of-plane deflections of the actuators with half-actuated and fully-actuated tethers were measured at about 17 μm and 29 μm respectively, in good agreement with FEA predictions of 17.1 μm and 25.8 μm. The corresponding blocking forces are predicted as 10 mN and 17 mN by FEA.
Huang, Pao-Cheng; Wang, Min-Haw; Chen, Ming-Kun; Jang, Ling-Sheng
2016-05-01
Flow rate sensing is a critical issue for piezoelectric-based micropump systems. This paper describes experimental analysis of flow rate sensing in a peristaltic micropump system. Sensing can be integrated with such a pump using piezoelectric actuators based on the time-phase-shift (TPS) method. To do this, an evaluation-window is added on the falling edge of the driving pulse to help detect the flow velocity without affecting the flow rate. We fabricate a prototype piezoelectric peristaltic micropump with three chambers and three piezoelectric actuators. The middle actuator works not only as an actuator for driving fluid but also as a transducer for sensing flow rate. An evaluation-window is performed to ascertain the relationship between the flow rate and the phase shift of output-signal responses from the transducer. The experimental results show that the evaluation-window response of flow rates in a piezoelectric peristaltic micropump has rates of from 5.56‒33.36 μl s-1. The results are extended to propose a practical flow rate sensor, the design of which can be realized easily in the piezoelectric peristaltic micropump system for sensorless responses that can detect flow rate without any sensors or circuits. The proposed TPS method is real-time, integrated, fast, efficient, and suitable for flow rate detection in piezoelectric peristaltic micropumps.
Wang, Hongjin; Meng, Qingfeng
2013-03-01
Power harvesting techniques that convert vibration energy into electrical energy through piezoelectric transducers show strong potential for powering smart wireless sensor devices in applications of structural health monitoring. This paper presents an analytical model of the dynamic behavior of an electromechanical piezoelectric bimorph cantilever harvester connected with an AC-DC circuit based on the Euler-Bernoulli beam theory and Hamiltonian theorem. A new cantilevered piezoelectric bimorph structure is proposed in which the plug-type connection between support layer and tip-mass ensures that the gravity center of the tip-mass is collinear with the gravity center of the beam so that the brittle fracture of piezoelectric layers can also be avoided while vibrating with large amplitude. The tip-mass is equated by the inertial force and inertial moment acting at the end of the piezoelectric bimorph beam based on D'Alembert's principle. An AC-DC converting circuit soldered with the piezoelectric elements is also taken into account. A completely new analytic expression of the global behavior of the electromechanical piezoelectric bimorph harvesting system with AC-DC circuit under input base transverse excitation is derived. Moreover, an experimental energy harvester is fabricated and the theoretical analysis and experimental results of the piezoelectric harvester under the input base transverse displacement excitation are validated by using measurements of the absolute tip displacement, electric voltage response, electric current response and electric power harvesting.
Resonance-type bimorph-based high-speed atomic force microscopy (HSAFM) capable of operating in the sample-scan and tip-scan modes is presented in this paper. The working principle of the high-speed scanner, the experimental setup, and the data collection system are described in detail. The main characteristic of the high-speed scanner is the use of a piezoelectric bimorph, where one of the piezoelectric layers is used to drive the bimorph beam to scan at a high speed and the other monitors the bimorph vibration. Image distortions due to the phase-lag and sinusoidal scanning are analyzed and simulated. The correction methods for the compensation of the phase-lag and nonlinear movement are proposed based on data shift and nonlinear mapping relations, respectively. The HSAFM imaging at the maximum rate of ∼30 frames per second is demonstrated with our data collection and correction program. The image distortions caused by the phase-lag and sinusoidal scanning are effectively eliminated in real-time. This work would provide useful methods for the development of HSAFM and applications in the observation of dynamic processes at nanoscale. (paper)
Portable Valve-less Peristaltic Micro-pump Design and Fabrication
Yang, H; Hu, C -C
2008-01-01
This paper is to describe a design and fabrication method for a valve-less peristaltic micro-pump. The valve-less peristaltic micro-pump with three membrane chambers in a serial is actuated by three piezoelectric (PZT) actuators. With the fluidic flow design, liquid in the flow channel is pumped to a constant flow speed ranged from 0.4 to 0.48 mm/s. In term of the maximum flow rate of the micro-pump is about 365 mircoliters/min, when the applied voltage is 24V and frequency 50 Hz. Photolithography process was used to fabricate the micro-pump mold. PDMS molding and PDMS bonding method were used to fabricate the micro-channel and actuator chambers. A portable drive controller was designed to control three PZT actuators in a proper sequence to drive the chamber membrane. Then, all parts were integrated into the portable valve-less peristaltic micro-pump system.
Peristaltic Pumping of Blood in micro-vessels of Non-uniform Cross-section
Misra, J C
2010-01-01
The paper is devoted to a study of the peristaltic motion of blood in the micro-circulatory system. The vessel is considered of non-uniform cross-section. The progressive peristaltic waves are taken to be of sinusoidal nature. The Reynolds number is considered to be small. Blood is considered to be a Herschel-Bulkley fluid. Of particular concern here is to investigate the effects of amplitude ratio, mean pressure gradient, yield stress and the power law index on the velocity distribution, streamline pattern and wall shear stress. Basing upon the study, extensive numerical calculations has been made. The study reveals that peristaltic pumping as well as velocity and wall shear stress are appreciably affected due to the non-uniform geometry of blood vessels. They are also highly sensitive to the magnitude of the amplitude of the amplitude ratio and the value of the fluid index.
Peristaltic transport of Carreau-Yasuda fluid in a curved channel with slip effects.
Tasawar Hayat
Full Text Available The wide occurrence of peristaltic pumping should not be surprising at all since it results physiologically from neuro-muscular properties of any tubular smooth muscle. Of special concern here is to predict the rheological effects on the peristaltic motion in a curved channel. Attention is focused to develop and simulate a nonlinear mathematical model for Carreau-Yasuda fluid. The progressive wave front of peristaltic flow is taken sinusoidal (expansion/contraction type. The governing problem is challenge since it has nonlinear differential equation and nonlinear boundary conditions even in the long wavelength and low Reynolds number regime. Numerical solutions for various flow quantities of interest are presented. Comparison for different flow situations is also made. Results of physical quantities are interpreted with particular emphasis to rheological characteristics.
Portable Valve-less Peristaltic Micro-pump Design and Fabrication
Yang, H.; Tsai, T.-H.; Hu, C.-C.
2008-01-01
This paper is to describe a design and fabrication method for a valve-less peristaltic micro-pump. The valve-less peristaltic micro-pump with three membrane chambers in a serial is actuated by three piezoelectric (PZT) actuators. With the fluidic flow design, liquid in the flow channel is pumped to a constant flow speed ranged from 0.4 to 0.48 mm/s. In term of the maximum flow rate of the micro-pump is about 365 mircoliters/min, when the applied voltage is 24V and frequency 50 Hz. Photolithog...
Munawwar Ali Abbas
2016-03-01
Full Text Available Entropy generation during peristaltic flow of nanofluids in a non-uniform two dimensional channel with compliant walls has been studied. The mathematical modelling of the governing flow problem is obtained under the approximation of long wavelength and zero Reynolds number (creeping flow regime. The resulting non-linear partial differential equations are solved with the help of a perturbation method. The analytic and numerical results of different parameters are demonstrated mathematically and graphically. The present analysis provides a theoretical model to estimate the characteristics of several Newtonian and non-Newtonian fluid flows, such as peristaltic transport of blood.
Flow Rate Driven by Peristaltic Movement in Plasmodial Tube of Physarum Polycephalum
Yamada, Hiroyasu; Nakagaki, Toshiyuki
2008-07-01
We report a theoretical analysis of protoplasmic streaming driven by peristaltic movement in an elastic tube of an amoeba-like organism. The Plasmodium of Physarum polycephalum, a true slime mold, is a large amoeboid organism that adopts a sheet-like form with a tubular network. The network extends throughout the Plasmodium and enables the transport and circulation of chemical signals and nutrients. This tubular flow is driven by periodically propagating waves of active contraction of the tube cortex, a process known as peristaltic movement. We derive the relationship between the phase velocity of the contraction wave and the flow rate, and we discuss the physiological implications of this relationship.
The self-generated peristaltic motion of cascaded pneumatic actuators for micro pumps
This paper presents a new actuation mechanism for the self-generated peristaltic motion of cascaded actuators and its application to micro pumps. The operational method is based on the fluidic circuit of an elastic tube. The elastic tube is modeled as a ladder network consisting of fluidic resistances in series and fluidic capacitances in parallel like multi-stage low-pass filters in an electrical circuit. All segments of the lumped model of the elastic tube have different dynamic characteristics because their time constants are different. In other words, all segments should be deformed sequentially like peristaltic motion. This phenomenon has good potential to cause peristaltic motion of the cascaded actuators in response to the application of single-phase pneumatic signals. Analogues between the electrical and fluidic circuits were applied to a pneumatic micro pump with a micro fluidic channel and three pneumatic actuators connecting a unique micro channel for supplying the compressed air. The polymeric micro pumps were fabricated with soft lithography using only polyimethylsiloxsane. The proposed working principle was verified through simulation of the static deformation of the cascaded actuator diaphragms and the actuator, as well as tested experimentally. The dual operational modes of the proposed device (i.e., rubber-seal valve and peristaltic pumping mode) were also verified and successfully demonstrated in a liquid pumping test of the single and double pumps
Development of Stepper motor based Two DOF Robotic Arm Transferring Liquid using Peristaltic Pump
Padma Thiagarajan
2013-02-01
Full Text Available The aim of this work is to transfer liquid contents from one micro cell to another using two stepper motors and a peristaltic pump. There are two objectives here. One is to develop a low cost roboticarm using stepper motors. The second objective is the control and calibration of the peristaltic pump. All parts are controlled and operated by their respective microcontrollers. Fulfillment of both the objectives leads to an integrated system to transfer liquids from one cell to another. The end effecter of the robotic arm is connected to the peristaltic pump. The pump has two pipes connected to it. Through one pipe it takes in the liquid and through the other pipe it delivers the liquid into the second cell. After transferring one sample of liquid, the arm moves to a cleaning module where the end effecter is cleaned to avoid cross contamination. The robotic arm is built using stepper motors and controlled using Atmega32 microcontroller whereas the peristaltic pump is controlled and calibrated using 8051 microcontroller. The pumping is done with the help of DC motors. As a result, the working of the robotic arm and theperistaltic pump is verified experimentally.
The self-generated peristaltic motion of cascaded pneumatic actuators for micro pumps
Jeong, Ok Chan; Konishi, Satoshi
2008-08-01
This paper presents a new actuation mechanism for the self-generated peristaltic motion of cascaded actuators and its application to micro pumps. The operational method is based on the fluidic circuit of an elastic tube. The elastic tube is modeled as a ladder network consisting of fluidic resistances in series and fluidic capacitances in parallel like multi-stage low-pass filters in an electrical circuit. All segments of the lumped model of the elastic tube have different dynamic characteristics because their time constants are different. In other words, all segments should be deformed sequentially like peristaltic motion. This phenomenon has good potential to cause peristaltic motion of the cascaded actuators in response to the application of single-phase pneumatic signals. Analogues between the electrical and fluidic circuits were applied to a pneumatic micro pump with a micro fluidic channel and three pneumatic actuators connecting a unique micro channel for supplying the compressed air. The polymeric micro pumps were fabricated with soft lithography using only polyimethylsiloxsane. The proposed working principle was verified through simulation of the static deformation of the cascaded actuator diaphragms and the actuator, as well as tested experimentally. The dual operational modes of the proposed device (i.e., rubber-seal valve and peristaltic pumping mode) were also verified and successfully demonstrated in a liquid pumping test of the single and double pumps.
A mathematical model for the peristaltic flow of chyme movement in small intestine.
Tripathi, Dharmendra
2011-10-01
A mathematical model based on viscoelastic fluid (fractional Oldroyd-B model) flow is considered for the peristaltic flow of chyme in small intestine, which is assumed to be in the form of an inclined cylindrical tube. The peristaltic flow of chyme is modeled more realistically by assuming that the peristaltic rush wave is a sinusoidal wave, which propagates along the tube. The governing equations are simplified by making the assumptions of long wavelength and low Reynolds number. Analytical approximate solutions of problem are obtained by using homotopy analysis method and convergence of the obtained series solution is properly checked. For the realistic values of the emerging parameters such as fractional parameters, relaxation time, retardation time, Reynolds number, Froude number and inclination of tube, the numerical results for the pressure difference and the frictional force across one wavelength are computed and discussed the roles played by these parameters during the peristaltic flow. On the basis of this study, it is found that the first fractional parameter, relaxation time and Froude number resist the movement of chyme, while, the second fractional parameter, retardation time, Reynolds number and inclination of tube favour the movement of chyme through the small intestine during pumping. It is further revealed that size of trapped bolus reduces with increasing the amplitude ratio whereas it is unaltered with other parameters. PMID:21802431
Peristaltic flow of a Maxwell fluid in a channel with compliant walls
Ali, Nasir [Department of Mathematics, Quaid-i-Azam University 45320, Islamabad 44000 (Pakistan)], E-mail: nasirali_qau@yahoo.com; Hayat, Tasawar [Department of Mathematics, Quaid-i-Azam University 45320, Islamabad 44000 (Pakistan); Asghar, Saleem [Department of Mathematical Sciences, COMSATS Institute of Information Technology, Islamabad (Pakistan)
2009-01-15
This paper describes the peristaltic motion of a non-Newtonian fluid in a channel having compliant boundaries. Constitutive equations for a Maxwell fluid have been used. Perturbation method has been used for the analytic solution. The influence of pertinent parameters is analyzed. Comparison of the present analysis of Maxwell fluid is made with the existing results of viscous fluid.
Slip and heat transfer effects on peristaltic motion of a Carreau fluid in an asymmetric channel
Hayat, Tasawar [Quaid-i-Azam Univ., Islamabad (Pakistan). Dept. of Mathematics; King Saud Univ., Riyadh (Saudi Arabia). Dept. of Mathematics; Saleem, Najma [Quaid-i-Azam Univ., Islamabad (Pakistan). Dept. of Mathematics; Hendi, Awatif A. [Dept. of Physics, Riyadh (Saudi Arabia). Faculty of Science
2010-12-15
An analysis has been carried out for peristaltic flow and heat transfer of a Carreau fluid in an asymmetric channel with slip effect. The governing problem is solved under long wavelength approximation. The variations of pertinent dimensionless parameters on temperature are discussed. Pumping and trapping phenomena are studied. (orig.)
Slip effects on the magnetohydrodynamic peristaltic flow of a maxwell fluid
Hayat, Tasawar [Quiad-I-Azam Univ., Islamabad (Pakistan). Dept. of Mathematics; King Saud Univ., Riyadh (Saudi Arabia). Dept. of Mathematics; Hina, Sadia [Quiad-I-Azam Univ., Islamabad (Pakistan). Dept. of Mathematics; Hendi, Awatif A. [Dept. of Physics, Riyadh (Saudi Arabia). Faculty of Science
2010-12-15
The influence of slip on the magnetohydrodynamic (MHD) peristaltic flow in a planar channel with compliant walls is examined. An incompressible Maxwell fluid saturates the porous medium. An established solution is valid for small wave number. The mathematical expression of the stream function is presented. Several interesting flow parameters are sketched and examined. (orig.)
The current paper presents a piezoelectric bimorph actuator produced by direct bonding of lithium niobate wafers with the mirrored Y and Z axes. Direct bonding technology allowed to fabricate bidomain plate with precise positioning of ideally flat domain boundary. By optimizing the cutting angle (128° Y-cut), the piezoelectric constant became as large as 27.3 pC/N. Investigation of voltage dependence of bending displacement confirmed that bimorph actuator has excellent linearity and hysteresis-free. Decrease of the applied voltage down to mV range showed the perfect linearity up to the sub-nm deflection amplitude. The frequency and temperature dependences of electromechanical transmission coefficient in wide temperature range (from 300 to 900 K) were investigated
Mechano-optical switching in a mems integrated photonic crystal slab waveguide
Abdulla, S.M.C.; Kauppinen, L.J.; Dijkstra, M.A.; Berenschot, J.W.; Boer, de M.J.; Ridder, de R.M.; Krijnen, G.J.M.
2011-01-01
A photonic crystal slab waveguide (PhC-WG) with an integrated MEMS bimorph cantilever actuator has been successfully fabricated using deep UV lithography and surface micromaching techniques. The cantilever is equipped with tips that are self-aligned with respect to the holes of the PhC-WG such that
Impulse excitation of piezoelectric bimorphs for energy harvesting: a dimensionless model
Energy harvesting (EH) is a multidisciplinary research area, involving physics, materials science and engineering, with the objective of providing renewable sources of power sufficient to operate targeted low-power applications. Piezoelectric transducers are often used for inertial vibrational as well as direct excitation EH. However, due to the stiffness of the most common material (PZT), compact and light-weight harvesters have high resonant frequencies, making them inefficient at extracting low-frequency power from the environment. The technique of frequency up-conversion, in the form of either plucking or impulse excitation, aims to bridge this frequency gap. In this paper, the technique is modelled analytically with focus on impulse excitation via impact or shock. An analytical model is developed in a standard way starting from the Euler–Bernoulli beam equations adapted to a piezoelectric bimorph. A set of dimensionless variables and parameters is defined and a system of differential equations derived. Here the system is solved numerically for a wide range of the two group parameters present, covering piezoelectric coupling strength between PVDF and PMN-PT. One major result is that the strength of the coupling strongly affects the timescale of the process, but has only a minor effect on the total energy converted. The model can be readily adapted to different excitation profiles. (paper)
Impulse excitation of piezoelectric bimorphs for energy harvesting: a dimensionless model
Pozzi, Michele
2014-04-01
Energy harvesting (EH) is a multidisciplinary research area, involving physics, materials science and engineering, with the objective of providing renewable sources of power sufficient to operate targeted low-power applications. Piezoelectric transducers are often used for inertial vibrational as well as direct excitation EH. However, due to the stiffness of the most common material (PZT), compact and light-weight harvesters have high resonant frequencies, making them inefficient at extracting low-frequency power from the environment. The technique of frequency up-conversion, in the form of either plucking or impulse excitation, aims to bridge this frequency gap. In this paper, the technique is modelled analytically with focus on impulse excitation via impact or shock. An analytical model is developed in a standard way starting from the Euler-Bernoulli beam equations adapted to a piezoelectric bimorph. A set of dimensionless variables and parameters is defined and a system of differential equations derived. Here the system is solved numerically for a wide range of the two group parameters present, covering piezoelectric coupling strength between PVDF and PMN-PT. One major result is that the strength of the coupling strongly affects the timescale of the process, but has only a minor effect on the total energy converted. The model can be readily adapted to different excitation profiles.
Peristaltic Pumping of Blood Through Small Vessels of Varying Cross-Section
Misra, J. C.; Maiti, S.
2012-11-01
The paper is devoted to a study of the peristaltic motion of blood in the micro-circulatory system. The vessel is considered to be of varying cross-section. The progressive peristaltic waves are taken to be of sinusoidal nature. Blood is considered to be a Herschel-Bulkley fluid. Of particular concern here is to investigate the effects of amplitude ratio, mean pressure gradient, yield stress and the power law index on the velocity distribution, streamline pattern and wall shear stress. On the basis of the derived analytical expression, extensive numerical calculations have been made. The study reveals that velocity of blood and wall shear stress are appreciably affected due to the non-uniform geometry of blood vessels. They are also highly sensitive to the magnitude of the amplitude ratio and the value of the fluid index.
A. M. Abd-Alla
2014-01-01
Full Text Available In this paper, the peristaltic flow of a Jeffrey fluid in an asymmetric channel has been investigated. Mathematical modeling is carried out by utilizing long wavelength and low Reynolds number assumptions. Closed form expressions for the pressure gradient, pressure rise, stream function, axial velocity, and shear stress on the channel walls have been computed numerically. Effects of the Hartmann number, the ratio of relaxation to retardation times, time-mean flow, the phase angle and the gravity field on the pressure gradient, pressure rise, streamline, axial velocity, and shear stress are discussed in detail and shown graphically. The results indicate that the effect of Hartmann number, ratio of relaxation to retardation times, time-mean flow, phase angle, and gravity field are very pronounced in the peristaltic transport phenomena. Comparison was made with the results obtained in the presence and absence of magnetic field and gravity field.
Design and dynamic characterization of "single-stroke" peristaltic PDMS micropumps.
Lai, Hoyin; Folch, Albert
2011-01-21
In this paper, we present a monolithic PDMS micropump that generates peristaltic flow using a single control channel that actuates a group of different-sized microvalves. An elastomeric microvalve design with a raised seat, which improves bonding reliability, is incorporated into the micropump. Pump performance is evaluated based on several design parameters--size, number, and connection of successive microvalves along with control channel pressure at various operating frequencies. Flow rates ranging 0-5.87 µL min(-1) were observed. The micropump design demonstrated here represents a substantial reduction in the number of/real estate taken up by the control lines that are required to run a peristaltic pump, hence it should become a widespread tool for parallel fluid processing in high-throughput microfluidics. PMID:20957288
Efficient worm-like locomotion: slip and control of soft-bodied peristaltic robots
In this work, we present a dynamic simulation of an earthworm-like robot moving in a pipe with radially symmetric Coulomb friction contact. Under these conditions, peristaltic locomotion is efficient if slip is minimized. We characterize ways to reduce slip-related losses in a constant-radius pipe. Using these principles, we can design controllers that can navigate pipes even with a narrowing in radius. We propose a stable heteroclinic channel controller that takes advantage of contact force feedback on each segment. In an example narrowing pipe, this controller loses 40% less energy to slip compared to the best-fit sine wave controller. The peristaltic locomotion with feedback also has greater speed and more consistent forward progress. (paper)
Kim, Moonkeun; Hwang, Beomseok; Jeong, Jaehwa; Min, Nam Ki; Kwon, Kwang-Ho
2012-07-01
We designed and fabricated a bimorph Pb(Zr,Ti)O3 (PZT) cantilever with an integrated Si proof mass to obtain a low resonant frequency for an energy harvesting application. The cantilevers were fabricated on the micro-electromechanical systems (MEMS) scale. A mode of piezoelectric conversions were d31 and d33 mode in cantilever vibration Therefore, we designed and fabricated a single cantilever with d31 unimorph, d31 bimorph, d33 unimorph, and d33 bimorph modes. Finally, we fabricated a device with beam dimensions of about 5,400 microm x 480 microm x 14 microm (< +/- 5%), and an integrated Si proof mass with dimensions of about 1,481 microm x 988 microm x 450 microm (< +/- 5%). In order to measure the d31 and d33 modes, we fabricated top and bottom electrodes. The distance between the top electrodes was 50 microm and the resonant frequency was 89.4 Hz. The average powers of the d31 unimorph, d31 bimorph, d33 unimorph, and d33 bimorph modes were 3.90, 9.60, 21.42, and 22.47 nW at 0.8 g (g = 9.8 m/s2) and optimal resistance, respectively. PMID:22966699
Development of a peristaltic micropump for bio-medical applications based on mini LIPCA
Pham, My; Nguyen, Thanh Tung; Goo, Nam Seo
2008-01-01
This paper presents the design, fabrication, and experimental characterization of a peristaltic micropump. The micropump is composed of two layers fabricated from polydimethylsiloxane (PDMS) material. The first layer has a rectangular channel and two valve seals. Three rectangular mini lightweight piezo-composite actuators are integrated in the second layer, and used as actuation parts. Two layers are bonded, and covered by two polymethyl methacrylate (PMMA) plates, which help increase the st...
M. K. Chaube; Tripathi, D.; O. Anwar Bég; Shashi Sharma; PANDEY, V.S.
2015-01-01
A mathematical study on creeping flow of non-Newtonian fluids (power law model) through a nonuniform peristaltic channel, in which amplitude is varying across axial displacement, is presented, with slip effects included. The governing equations are simplified by employing the long wavelength and low Reynolds number approximations. The expressions for axial velocity, stream function, pressure gradient, and pressure difference are obtained. Computational and numerical results for velocity profi...
Dr.S.Ravi kumar
2013-01-01
In this paper we have analyzed the flow of a couple stress fluids in a channel bounded by flexible walls over which a traveling wave of contraction and expansion is imposed resulting in a peristaltic motion. An oscillatory time dependent flow is also imposed on this flow. The non-linear equations governing the flow through magnetic field are solved under long wavelength approximation. The existence of separation in the flow field is discussed for different values of the governing parameters. ...
Effect of induced magnetic field on peristaltic flow of a micropolar fluid in an asymmetric channel
Shit, G. C.; Roy, M.; E. Y. K. Ng
2010-01-01
Of concern in this paper is an investigation of peristaltic transport of a physiological fluid in an asymmetric channel under long wave length and low-Reynolds number assumptions. The flow is assumed to be incompressible, viscous, electrically conducting micropolar fluid and the effect of induced magnetic field is taken into account. Exact analytical solutions obtained for the axial velocity, microrotation component, stream line pattern, magnetic force function, axial-induced magnetic field a...
Peristaltic transport of Johnson-Segalman fluid under effect of a magnetic field
Moustafa Elshahed
2005-01-01
Full Text Available The peristaltic transport of Johnson-Segalman fluid by means of an infinite train of sinusoidal waves traveling along the walls of a two-dimensional flexible channel is investigated. The fluid is electrically conducted by a transverse magnetic field. A perturbation solution is obtained for the case in which amplitude ratio is small. Numerical results are reported for various values of the physical parameters of interest.
Non-Newtonian effects in the peristaltic flow of a Maxwell fluid
Tsiklauri, D.; Beresnev, I.
2001-01-01
We analyzed the effect of viscoelasticity on the dynamics of fluids in porous media by studying the flow of a Maxwell fluid in a circular tube, in which the flow is induced by a wave traveling on the tube wall. The present study investigates novelties brought about into the classic peristaltic mechanism by inclusion of non-Newtonian effects that are important, for example, for hydrocarbons. This problem has numerous applications in various branches of science, including stimulation of fluid f...
A Mathematical Model for Studying the Slip Effect on Peristaltic Motion with Heat and Mass Transfer
Tasawar Hayat; Najma Saleem; Awatif A. Hendi
2011-01-01
A mathematical model is presented with an interest to examine the peristaltic motion in an asymmetric channel by taking into account the slip, heat and mass transfer. Constitutive relationships for a micropolar fluid are used. The solution procedure for nonlinear analysis is given under long wavelength and low Reynolds number approximations. The effects of sundry parameters entering into the expressions of axial velocity,temperature and concentration are explored. Pumping and trapping phenomena are discussed.
Dynamic simulation of a peristaltic micropump considering coupled fluid flow and structural motion
Lin, Qiao; Yang, Bozhi; Xie, Jun; Tai, Yu-Chong
2007-02-01
This paper presents lumped-parameter simulation of dynamic characteristics of peristaltic micropumps. The pump consists of three pumping cells connected in series, each of which is equipped with a compliant diaphragm that is electrostatically actuated in a peristaltic sequence to mobilize the fluid. Diaphragm motion in each pumping cell is first represented by an effective spring subjected to hydrodynamic and electrostatic forces. These cell representations are then used to construct a system-level model for the entire pump, which accounts for both cell- and pump-level interactions of fluid flow and diaphragm vibration. As the model is based on first principles, it can be evaluated directly from the device's geometry, material properties and operating parameters without using any experimentally identified parameters. Applied to an existing pump, the model correctly predicts trends observed in experiments. The model is then used to perform a systematic analysis of the impact of geometry, materials and pump loading on device performance, demonstrating its utility as an efficient tool for peristaltic micropump design.
Particle motion in unsteady two-dimensional peristaltic flow with application to the ureter
Jiménez-Lozano, Joel; Sen, Mihir; Dunn, Patrick F.
2009-04-01
Particle motion in an unsteady peristaltic fluid flow is analyzed. The fluid is incompressible and Newtonian in a two-dimensional planar geometry. A perturbation method based on a small ratio of wave height to wavelength is used to obtain a closed-form solution for the fluid velocity field. This analytical solution is used in conjunction with an equation of motion for a small rigid sphere in nonuniform flow taking Stokes drag, virtual mass, Faxén, Basset, and gravity forces into account. Fluid streamlines and velocity profiles are calculated. Theoretical values for pumping rates are compared with available experimental data. An application to ureteral peristaltic flow is considered since fluid flow in the ureter is sometimes accompanied by particles such as stones or bacteriuria. Particle trajectories for parameters that correspond to calcium oxalates for calculosis and Escherichia coli type for bacteria are analyzed. The findings show that retrograde or reflux motion of the particles is possible and bacterial transport can occur in the upper urinary tract when there is a partial occlusion of the wave. Dilute particle mixing is also investigated, and it is found that some of the particles participate in the formation of a recirculating bolus, and some of them are delayed in transit and eventually reach the walls. This can explain the failure of clearing residuals from the upper urinary tract calculi after successful extracorporeal shock wave lithotripsy. The results may also be relevant to the transport of other physiological fluids and industrial applications in which peristaltic pumping is used.
Peristaltic flow in non-uniform vessels of the micro-circulatory system
Maiti, S
2013-01-01
Of concern in the paper is generalized a theoretical study concerning the peristaltic flow of blood in the micro-circulatory system. The vessel is considered to be of non-uniform cross-section and blood to be a non-Newtonian fluid. The progressive wave front of the peristaltic flow is supposed sinusoidal/straight section dominated (SSD) (expansion/contraction type); Reynolds number is considered to be small with reference to the flow of physiological fluids. The non-Newtonian behaviour of blood is illustrated by considering the Herschel-Bulkley fluid model. The objective of the study has been to examine the effect of the effects of amplitude ratio, mean pressure gradient, yield stress and the power law index on the velocity distribution, wall shear stress, streamline pattern and trapping. Considerable quantitative differences between the results obtained for transport in two dimensional channel and an axisymmetric circular tube are noticed. The study shows that peristaltic pumping, flow velocity and wall shea...
Effect of actuation sequence on flow rates of peristaltic micropumps with PZT actuators.
Jang, Ling-Sheng; Shu, Kuan; Yu, Yung-Chiang; Li, Yuan-Jie; Chen, Chiun-Hsun
2009-02-01
Many biomedical applications require the administration of drugs at a precise and preferably programmable rate. The flow rate generated by the peristaltic micropumps used in such applications depends on the actuation sequence. Accordingly, the current study performs an analytical and experimental investigation to determine the correlation between the dynamic response of the diaphragms in the micropump and the actuation sequence. A simple analytical model of a peristaltic micropump is established to analyze the shift in the resonant frequency of the diaphragms caused by the viscous damping effect. The analytical results show that this damping effect increases as the oscillation frequency of the diaphragm increases. A peristaltic micropump with three piezoelectric actuators is fabricated on a silicon substrate and is actuated using 2-, 3-, 4- and 6-phase actuation sequences via a driving system comprising a microprocessor and a phase controller. A series of experiments is conducted using de-ionized water as the working fluid to determine the diaphragm displacement and the flow rates induced by each of the different actuation sequences under phase frequencies ranging from 50 Hz to 1 MHz. The results show that the damping effect of actuation sequences influences diaphragm resonant frequency, which in turn affects the profiles of flow rates. PMID:18821016
Gastrointestinal monitor: automatic titration of jejunal inflow to match peristaltic outflow.
Moss, Gerald; Posada, Jose G
2007-06-15
A peristaltic gradient insures that chyme normally removed from the jejunal feeding site continues to be propelled caudad. The trigger for iatrogenic "feeding intolerance" is the inadvertently overwhelming of the jejunum's peristaltic outflow, even momentarily. Even minimum local stasis can stimulate a vagal reflex response. Motility of the sluggish gut further slows, leading to generalized abdominal distention, malaise, immobility, and impaired respiratory mechanics. Vagal vascular reflexes could explain the 1:1000 incidence of bowel necrosis for jejunally fed patients. We developed a clinical regimen that continuously "checks for residual" at the enteral feeding site, monitoring the adequacy of emptying. The jejunal inflow automatically is titrated to match peristaltic outflow if the latter cannot keep up. Intermittent suction aspirates the feeding catheter into a plastic chamber for 30 s. All swallowed air is removed efficiently within the close confines of the jejunal segment, without wasting digestive juices. The degassed aspirate is returned by gravity with the feedings during the second half of the 1-min cycle, unless incipient excess (>or=20 mL) fluid overflows. Only this relatively small volume of potentially excess fluid is discarded, forestalling the local distention. All patients tolerated immediate feeding without discomfort or abdominal distention, including three that had esophageal resection (including vagotomy) for carcinoma. Postoperative full enteral nutrition can be achieved quickly and safely with minimum attention, despite initially marginal gastrointestinal function. PMID:17509263
Zhao, S.; Erturk, A.
2013-01-01
We present electroelastic modeling, analytical and numerical solutions, and experimental validations of piezoelectric energy harvesting from broadband random vibrations. The modeling approach employed herein is based on a distributed-parameter electroelastic formulation to ensure that the effects of higher vibration modes are included, since broadband random vibrations, such as Gaussian white noise, might excite higher vibration modes. The goal is to predict the expected value of the power output and the mean-square shunted vibration response in terms of the given power spectral density (PSD) or time history of the random vibrational input. The analytical method is based on the PSD of random base excitation and distributed-parameter frequency response functions of the coupled voltage output and shunted vibration response. The first of the two numerical solution methods employs the Fourier series representation of the base acceleration history in an ordinary differential equation solver while the second method uses an Euler-Maruyama scheme to directly solve the resulting electroelastic stochastic differential equations. The analytical and numerical simulations are compared with several experiments for a brass-reinforced PZT-5H bimorph under different random excitation levels. The simulations exhibit very good agreement with the experimental measurements for a range of resistive electrical boundary conditions and input PSD levels. It is also shown that lightly damped higher vibration modes can alter the expected power curve under broadband random excitation. Therefore, the distributed-parameter modeling and solutions presented herein can be used as a more accurate alternative to the existing single-degree-of-freedom solutions for broadband random vibration energy harvesting.
Bagdasaryan G. Y.
2016-03-01
Full Text Available A comprehensive theoretical analysis of a dynamic thermo-ferro-electric pre-stressed bimorph energy harvester is performed. The analysis also takes into account pyroelectric and thermal expansion effects. The most general analytical expression for the energy conversation coefficients are presented for bi-layer. These coefficients we derive for more general situation when mechanical, electrical, thermal fields are present. We derive coefficients (transformation coefficients for sensing, actuating, and energy harvesting. As a particular case, we derive an analytical expression for the energy harvesting coefficient due to pyroelectric and thermal expansion effects in a rater general situation. This is a function of material properties, location of boundary conditions, vibration frequency, and in plane compressive/tensile follower force. Numerical simulations of the analytical results are presented. Effects of volume fraction, material properties, applied mechanical loads, and boundary conditions on the harvesting coefficients are introduced in the figures. The results for a cantilever and a simply-supported plate-layer are obtained as particular cases. The result for a low frequency (static system is obtained as a particular case by approaching the vibration frequency to zero. It is shown that volume fraction, material properties, plain compressive/tensile follower force, the location of the boundary conditions, and the vibrational frequency of the bimorph strongly influence the strain distribution, and this in effect influences the charge coefficient and the generation of energy. The proposed model can be extended to thermal energy harvesters of piezoelectric-shape memory alloy (SMA composites.
In this paper the effects of induced magnetic field on the peristaltic transport of a Williamson fluid model in an asymmetric channel has been investigated. The problem is simplified by using long wave length and low Reynolds number approximations. The perturbation and numerical solutions have been presented. The expressions for pressure rise, pressure gradient, stream function, magnetic force function, current density distribution have been computed. The results of pertinent parameters have been discussed graphically. The trapping phenomena for different wave forms have been also discussed. - highlights: • The main motivation of this work is that we want to see the behavior of peristaltic flow of Williamson fluid in the occurrence of induced magnetic field. In literature no attempt is taken to discuss the lateral Numerical and analytical treatment on peristaltic flow of Williamson fluid in the occurrence of induced magnetic field. • We do not want to fill the gap in literature after studying this
Fabrication of magnetoresistive actuators using rare-earth (Tb, Sm)-Fe thin films
Honda, T.; Arai, K. I.; Yamaguchi, M.
1994-11-01
A new concept is proposed for the microactuation based upon magnetostriction. Magnetostrictive bimorph cantilever actuators and a traveling machine, composed of the magnetostrictive amorphous Tb-Fe and Sm-Fe thin films on a polymide substrate, were fabricated. These actuators moved without power supply cables. The 3-mm-long cantilever actuator exhibited the large deflection above 100 microns in as low a magnetic field as 300 Oe and above 500 microns at resonant frequency in an alternating magnetic field of 300 Oe. Such unique characteristics suggest that magnetostriction is useful as the driving force of the microactuator.
A Peristaltic Micro Pump Driven by a Rotating Motor with Magnetically Attracted Steel Balls
Zhaoying Zhou; Kang Wu; Xiongying Ye; Min Du
2009-01-01
In this paper, we present a membrane peristaltic micro pump driven by a rotating motor with magnetically attracted steel balls for lab-on-a-chip applications. The fabrication process is based on standard soft lithography technology and bonding of a PDMS layer with a PMMA substrate. A linear flow rate range ~490 μL/min was obtained by simply varying the rotation speed of a DC motor, and a maximum back pressure of 592 Pa was achieved at a rotation speed of 43 rpm. The flow rate of the pump can ...
Peristaltic transport of Conducting Bingham fluid in contact with a Newtonian fluid in a channel
M.Arun kumar
2013-04-01
Full Text Available Peristaltic pumping by a sinusoidal traveling wave in the walls of a two dimensional channel filled with two immiscible fluids with magnetic effect is investigated. The core region of the channel is occupied by a Bingham fluid where as the peripheral region is occupied by a Newtonian fluid. The flow is examined in a wave frame of reference moving with the velocity of the wave. The expressions for the stream function, the velocity and the pressure rise are obtained. The equation for the interface separating the two fluids is obtained. Numerical results are reported for several of the physical parameters of interest. We observed that the lower values of
Magnetohydrodynamic Peristaltic Flow of a Pseudoplastic Fluid in a Curved Channel
Noreen, Saima; Hayat, Tasawar; Alsaedi, Ahmed
2013-05-01
A mathematical model is developed to examine the effects of an induced magnetic field on the peristaltic flow in a curved channel. The non-Newtonian pseudoplastic fluid model is used to depict the combined elastic and viscous properties. The analysis has been carried out in the wave frame of reference, long wavelength and low Reynolds scheme are implemented. A series solution is obtained through perturbation analysis. Results for stream function, pressure gradient, magnetic force function, induced magnetic field, and current density are constructed. The effects of significant parameters on the flow quantities are sketched and discussed.
Hayat, T.; Iqbal, Rija; Tanveer, Anum; Alsaedi, A.
2016-06-01
This paper looks at the influences of magnetohydrodynamics (MHD) and thermal radiation on peristaltic transport of a pseudoplastic nanofluid in a tapered asymmetric channel. The tapered channel walls satisfy convective boundary conditions. The governing equations for the balance of mass, momentum, temperature and volume fraction for pseudoplastic nanofluid are first formulated and then utilized for long wavelength and small Reynolds number considerations. Effects of involved parameters on the flow characteristics have been plotted and examined. It is observed that the heat transfer Biot number shows a dual behavior on the temperature of nanofluid particles whereas the mass transfer Biot number with its increasing values enhances the fluid temperature.
Peristaltic flow in an asymmetric channel with convective boundary conditions and Joule heating
Abbasi Fahad Munir; Hayat Tasawar; Ahmad Bashir
2014-01-01
The peristaltic transport of viscous fluid in an asymmetric channel is concentrated. The channel walls exhibit convective boundary conditions. Both cases of hydrodynamic and magnetohydrodynamic (MHD) fluids are considered. Mathematical analysis has been presented in a wave frame of reference. The resulting problems are non-dimensionalized. Long wavelength and low Reynolds number approximations are employed. Joule heating effect on the thermal equation is retained. Analytic solutions for stream function and temperature are constructed. Numerical integration is carried out for pressure rise per wavelength. Effects of influential flow parameters have been pointed out through graphs.
Sohail Nadeem; Safia Akram
2011-01-01
In the present paper we discuss the magnetohydrodynamic (MHD) peristaltic flow of a hyperbolic tangent fluid model in a vertical asymmetric channel under a zero Reynolds number and long wavelength approximation. Exact solution of the temperature equation in the absence of dissipation term has been computed and the analytical expression for stream function and axial pressure gradient are established. The flow is analyzed in a wave frame of reference moving with the velocity of wave. The expression for pressure rise has been computed numerically. The physical features of pertinent parameters are analyzed by plotting graphs and discussed in detail.
Rachid, Hassan
2015-12-01
In the present study,we investigate the unsteady peristaltic transport of a viscoelastic fluid with fractional Burgers' model in an inclined tube. We suppose that the viscosity is variable in the radial direction. This analysis has been carried out under low Reynolds number and long-wavelength approximations. An analytical solution to the problem is obtained using a fractional calculus approach. Figures are plotted to show the effects of angle of inclination, Reynolds number, Froude number, material constants, fractional parameters, parameter of viscosity and amplitude ratio on the pressure gradient, pressure rise, friction force, axial velocity and on the mechanical efficiency.
Mixed convection peristaltic flow of third order nanofluid with an induced magnetic field.
Saima Noreen
Full Text Available This research is concerned with the peristaltic flow of third order nanofluid in an asymmetric channel. The governing equations of third order nanofluid are modelled in wave frame of reference. Effect of induced magnetic field is considered. Long wavelength and low Reynolds number situation is tackled. Numerical solutions of the governing problem are computed and analyzed. The effects of Brownian motion and thermophoretic diffusion of nano particles are particularly emphasized. Physical quantities such as velocity, pressure rise, temperature, induced magnetic field and concentration distributions are discussed.
Peristaltic flow of Johnson-Segalman fluid in asymmetric channel with convective boundary conditions
H YASMIN; T HAYAT; A ALSAEDI; HH ALSULAMI
2014-01-01
This work is concerned with the peristaltic transport of the Johnson-Segalman fluid in an asymmetric channel with convective boundary conditions. The mathematical modeling is based upon the conservation laws of mass, linear momentum, and energy. The resulting equations are solved after long wavelength and low Reynolds number are used. The results for the axial pressure gradient, velocity, and temperature profiles are obtained for small Weissenberg number. The expressions of the pressure gra-dient, velocity, and temperature are analyzed for various embedded parameters. Pumping and trapping phenomena are also explored.
Effect of Slip on Peristaltic Flow of Powell-Eyring Fluid in a Symmetric Channel
T. Hayat
2014-01-01
Full Text Available Peristaltic flow of non-Newtonian fluid in a symmetric channel with partial slip effect is examined. The non-Newtonian behavior of fluid is characterized by the constitutive equations of Powell-Eyring fluid. The motion is induced by a sinusoidal wave traveling along the flexible walls of channel. The flow is analyzed in a wave frame of reference moving with the velocity of wave. The equations governing the flow are solved by adopting lubrication approach. Series solutions for the stream function and axial pressure gradient are obtained. Impact of slip and other emerging flow parameters is plotted and analyzed graphically.
Radiative Peristaltic Flow of Jeffrey Nanofluid with Slip Conditions and Joule Heating
Hayat, Tasawar; Shafique, Maryam; Tanveer, Anum; Alsaedi, Ahmed
2016-01-01
Mixed convection peristaltic flow of Jeffrey nanofluid in a channel with compliant walls is addressed here. The present investigation includes the viscous dissipation, thermal radiation and Joule heating. Whole analysis is performed for velocity, thermal and concentration slip conditions. Related problems through long wavelength and low Reynolds number are examined for stream function, temperature and concentration. Impacts of thermal radiation, Hartman number, Brownian motion parameter, thermophoresis, Joule heating and slip parameters are explored in detail. Clearly temperature is a decreasing function of Hartman number and radiation parameter. PMID:26886919
Akbar, Noreen Sher
2016-03-01
The peristaltic flow of an incompressible viscous fluid containing copper nanoparticles in an asymmetric channel is discussed with thermal and velocity slip effects. The copper nanoparticles for the peristaltic flow water as base fluid is not explored so far. The equations for the purposed fluid model are developed first time in literature and simplified using long wavelength and low Reynolds number assumptions. Exact solutions have been calculated for velocity, pressure gradient, the solid volume fraction of the nanoparticles and temperature profile. The influence of various flow parameters on the flow and heat transfer characteristics is obtained.
Sher Akbar, Noreen
2015-03-01
The influence of magnetic field on peristaltic flow of a Casson fluid model is considered. The model for peristaltic literature is modelled first time. The governing coupled equations are constructed under long wavelength and low Reynold's number approximation. Exact solutions are evaluated for stream function and pressure gradient. The important findings in this study are the variation of the Hartmann number M, Casson fluid parameter ζ and amplitudes a, b, d and ϕ. The velocity field increases due to increase in Hartmann number M near the channel walls while velocity field decreases at the centre of the channel.
Hayat, Tasawar; Rafiq, Maimona; Ahmad, Bashir
2016-01-01
The objective of present paper is to examine the peristaltic flow of magnetohydrodynamic (MHD) Jeffrey fluid saturating porous space in a channel through rotating frame. Unlike the previous attempts, the flow formulation is based upon modified Darcy's law porous medium effect in Jeffrey fluid situation. In addition the impacts due to Soret and Dufour effects in the radiative peristaltic flow are accounted. Rosseland’s approximation has been utilized for the thermal radiative heat flux. Lubrication approach is implemented for the simplification. Resulting problems are solved for the stream function, temperature and concentration. Graphical results are prepared and analyzed for different parameters of interest entering into the problems. PMID:26808387
Hayat, Tasawar; Rafiq, Maimona; Ahmad, Bashir
2016-01-01
The objective of present paper is to examine the peristaltic flow of magnetohydrodynamic (MHD) Jeffrey fluid saturating porous space in a channel through rotating frame. Unlike the previous attempts, the flow formulation is based upon modified Darcy's law porous medium effect in Jeffrey fluid situation. In addition the impacts due to Soret and Dufour effects in the radiative peristaltic flow are accounted. Rosseland's approximation has been utilized for the thermal radiative heat flux. Lubrication approach is implemented for the simplification. Resulting problems are solved for the stream function, temperature and concentration. Graphical results are prepared and analyzed for different parameters of interest entering into the problems. PMID:26808387
Li, Xuequan; Liu, Mengmeng; Huang, Baisheng; Liu, Hong; Hu, Weiguo; Shao, Li-Hua; Wang, Zhong Lin
2016-01-01
We firstly designed an electrochemical system for dealloying to synthesize nanoporous gold (NPG) and also driving the novel NPG based actuator by utilizing a modified rotary triboelectric nanogenerator (TENG). Compared to the previous reported TENG whose outputs decline due to temperature rising resulting from electrodes friction, the modified TENG with a cooling system has stable output current and voltage increased by 14% and 20%, respectively. The novel cantilevered hybrid actuator characterised by light-weight (ca. 3 mg) and small volume (ca. 30 mm × 2 mm × 10 μm) is driven by a microcontroller modulated TENG with the displacement of 2.2 mm, which is about 106 times larger than that of traditional cantilever using planar surfaces. The energy conversion efficiencies defined as the energy consumed during dealloying and actuation compared with the output of TENG are 47% and 56.7%, respectively. PMID:27063987
In this paper, the peristaltic flow of a Jeffrey fluid in an asymmetric rotating channel is studied. Mathematical modeling is carried out by utilizing long wavelength and low Reynolds number assumptions. Closed form expressions for the pressure gradient, pressure rise, streamlines, axial velocity and shear stress on the channel walls have been computed numerically. Effects of Hartmann number, the ratio of relaxation to retardation times, time-mean flow, rotation and the phase angle on the pressure gradient, pressure rise, streamline, axial velocity and shear stress are discussed in detail and shown graphically. The results indicate that the effect of the Hartmann number, the ratio of relaxation to retardation times, time-mean flow, rotation and the phase angle are very pronounced in the phenomena. Comparison was made with the results obtained in the asymmetric channel and symmetric channel. - Highlights: • The peristaltic flow of a Jeffrey fluid in an asymmetric rotating channel with magnetic field. • Mathematical modeling for long wavelength and low Reynolds number assumptions. • Closed form expressions for the pressure gradient, pressure rise, stream function, axial velocity and shear stress
Williamson Fluid Model for the Peristaltic Flow of Chyme in Small Intestine
Sohail Nadeem
2012-01-01
Full Text Available Mathematical model for the peristaltic flow of chyme in small intestine along with inserted endoscope is considered. Here, chyme is treated as Williamson fluid, and the flow is considered between the annular region formed by two concentric tubes (i.e., outer tube as small intestine and inner tube as endoscope. Flow is induced by two sinusoidal peristaltic waves of different wave lengths, traveling down the intestinal wall with the same speed. The governing equations of Williamson fluid in cylindrical coordinates have been modeled. The resulting nonlinear momentum equations are simplified using long wavelength and low Reynolds number approximations. The resulting problem is solved using regular perturbation method in terms of a variant of Weissenberg number We. The numerical solution of the problem is also computed by using shooting method, and comparison of results of both solutions for velocity field is presented. The expressions for axial velocity, frictional force, pressure rise, stream function, and axial pressure gradient are obtained, and the effects of various emerging parameters on the flow characteristics are illustrated graphically. Furthermore, the streamlines pattern is plotted, and it is observed that trapping occurs, and the size of the trapped bolus varies with varying embedded flow parameters.
Slip Effects on Peristaltic Transport of a Particle-Fluid Suspension in a Planar Channel
Mohammed H. Kamel
2015-01-01
Full Text Available Peristaltic pumping induced by a sinusoidal traveling wave in the walls of a two-dimensional channel filled with a viscous incompressible fluid mixed with rigid spherical particles is investigated theoretically taking the slip effect on the wall into account. A perturbation solution is obtained which satisfies the momentum equations for the case in which amplitude ratio (wave amplitude/channel half width is small. The analysis has been carried out by duly accounting for the nonlinear convective acceleration terms and the slip condition for the fluid part on the wavy wall. The governing equations are developed up to the second order of the amplitude ratio. The zeroth-order terms yield the Poiseuille flow and the first-order terms give the Orr-Sommerfeld equation. The results show that the slip conditions have significant effect within certain range of concentration. The phenomenon of reflux (the mean flow reversal is discussed under slip conditions. It is found that the critical reflux pressure is lower for the particle-fluid suspension than for the particle-free fluid and is affected by slip condition. A motivation of the present analysis has been the hope that such theory of two-phase flow process under slip condition is very useful in understanding the role of peristaltic muscular contraction in transporting biofluid behaving like a particle-fluid mixture. Also the theory is important to the engineering applications of pumping solid-fluid mixture by peristalsis.
Peristaltic Transport of a Rheological Fluid: Model for Movement of Food Bolus Through Esophagus
Misra, J C
2011-01-01
Fluid mechanical peristaltic transport through esophagus has been of concern in the paper. A mathematical model has been developed with an aim to study the peristaltic transport of a rheological fluid for arbitrary wave shapes and tube lengths. The Ostwald-de Waele power law of viscous fluid is considered here to depict the non-Newtonian behaviour of the fluid. The model is formulated and analyzed with the specific aim of exploring some important information concerning the movement of food bolus through the esophagus. The analysis has been carried out by using lubrication theory. The study is particularly suitable for cases where the Reynolds number is small. The esophagus is treated as a circular tube through which the transport of food bolus takes places by periodic contraction of the esophageal wall. Variation of different variables concerned with the transport phenomena such as pressure, flow velocity, particle trajectory and reflux are investigated for a single wave as well as for a train of periodic per...
Tripathi, Dharmendra; Bég, O Anwar
2012-08-01
Magnetohydrodynamic peristaltic flows arise in controlled magnetic drug targeting, hybrid haemodynamic pumps and biomagnetic phenomena interacting with the human digestive system. Motivated by the objective of improving an understanding of the complex fluid dynamics in such flows, we consider in the present article the transient magneto-fluid flow and heat transfer through a finite length channel by peristaltic pumping. Reynolds number is small enough and the wavelength to diameter ratio is large enough to negate inertial effects. Analytical solutions for temperature field, axial velocity, transverse velocity, pressure gradient, local wall shear stress, volume flowrate and averaged volume flowrate are obtained. The effects of the transverse magnetic field, Grashof number and thermal conductivity on the flow patterns induced by peristaltic waves (sinusoidal propagation along the length of channel) are studied using graphical plots. The present study identifies that greater pressure is required to propel the magneto-fluid by peristaltic pumping in comparison to a non-conducting Newtonian fluid, whereas, a lower pressure is required if heat transfer is effective. The analytical solutions further provide an important benchmark for future numerical simulations. PMID:23057236
The influence of magnetic field on peristaltic flow of a Casson fluid model is considered. The model for peristaltic literature is modelled first time. The governing coupled equations are constructed under long wavelength and low Reynold's number approximation. Exact solutions are evaluated for stream function and pressure gradient. The important findings in this study are the variation of the Hartmann number M, Casson fluid parameter ζ and amplitudes a, b, d and ϕ. The velocity field increases due to increase in Hartmann number M near the channel walls while velocity field decreases at the centre of the channel. - Highlights: • The influence of magnetic field on peristaltic flow of a Casson fluid model is considered. • The model for peristaltic literature is modelled first time. • The governing coupled equations are constructed under long wavelength and low Reynold's number approximation. • Exact solutions are evaluated for stream function and pressure gradient. • The velocity field increases due to increase in Hartmann number M near the channel walls while velocity field decreases at the centre of the channel
A Mathematical Model for Peristaltic Transport of Micro-Polar Fluids
S. K. Pandey
2011-01-01
Full Text Available A mathematical model has been constructed for peristaltic transport of micro-polar fluid in a circular cylindrical tube of finite length by letting sinusoidal waves propagate along the wall that induce contraction and relaxation but not expansion beyond the natural boundary. Axial and radial velocities and micro-rotation components are formulated for micro-polar fluid transportations by applying the method of long wavelength and low Reynolds number approximations in the analysis. Pressure distribution along the tube length is studied to investigate temporal effects. An in-depth study has been done to learn the effects of coupling number and micro-polar parameter. The effects of coupling number and micro-polar parameter are investigated also on mechanical efficiency, reflux and trapping. A significant difference observed is that unlike integral wave-trains propagating along the tube walls that have identical peaks of pressure, non-integral wave-trains have peaks of different sizes.
Development of a peristaltic micropump for bio-medical applications based on mini LIPCA
Pham, My; Goo, Nam Seo
2008-01-01
This paper presents the design, fabrication, and experimental characterization of a peristaltic micropump. The micropump is composed of two layers fabricated from polydimethylsiloxane (PDMS) material. The first layer has a rectangular channel and two valve seals. Three rectangular mini lightweight piezo-composite actuators are integrated in the second layer, and used as actuation parts. Two layers are bonded, and covered by two polymethyl methacrylate (PMMA) plates, which help increase the stiffness of the micropump. A maximum flow rate of 900 mokroliter per min and a maximum backpressure of 1.8 kPa are recorded when water is used as pump liquid. We measured the power consumption of the micropump. The micropump is found to be a promising candidate for bio-medical application due to its bio-compatibility, portability, bidirectionality, and simple effective design.
Development of a peristaltic gas micropump with a single chamber and multiple electrodes
This paper reports on the development of a multi-electrode electrostatically driven peristaltic gas micropump. The micropump consists of a single chamber and a flexible diaphragm with a multi-electrode pattern. The single-chamber design is divided into smaller cells by the electrodes; the characteristic operating frequency of the micropump increases as the number of electrodes increases. The flow rate is also observed to increase to maximum before decreasing for larger numbers of electrodes. Whereas the maximum flow rate of a 4-electrode micropump is about 40 µl min−1 at 14 Hz, the maximum flow rate of the 16-electrode micropump is about 250 µl min−1 at 1400 Hz and that of the 32-electrode micropump is 150 µl min−1 at 4000 Hz. (paper)
Simulations of peristaltic slip-flow of hydromagnetic bio-fluid in a curved channel
N. Ali
2016-02-01
Full Text Available The influence of slip and magnetic field on transport characteristics of a bio-fluid are analyzed in a curved channel. The problem is modeled in curvilinear coordinate system under the assumption that the wavelength of the peristaltic wave is larger in magnitude compared to the width of the channel. The resulting nonlinear boundary value problem (BVP is solved using an implicit finite difference technique (FDT. The flow velocity, pressure rise per wavelength and stream function are illustrated through graphs for various values of rheological and geometrical parameters of the problem. The study reveals that a thin boundary layer exists at the channel wall for strong magnetic field. Moreover, small values of Weissenberg number counteract the curvature and make the velocity profile symmetric. It is also observed that pressure rise per wavelength in pumping region increases (decreases by increasing magnetic field, Weissenberg number and curvature of the channel (slip parameter.
A peristaltic micro pump driven by a rotating motor with magnetically attracted steel balls.
Du, Min; Ye, Xiongying; Wu, Kang; Zhou, Zhaoying
2009-01-01
In this paper, we present a membrane peristaltic micro pump driven by a rotating motor with magnetically attracted steel balls for lab-on-a-chip applications. The fabrication process is based on standard soft lithography technology and bonding of a PDMS layer with a PMMA substrate. A linear flow rate range ∼490 μL/min was obtained by simply varying the rotation speed of a DC motor, and a maximum back pressure of 592 Pa was achieved at a rotation speed of 43 rpm. The flow rate of the pump can also be adjusted by using steel balls with different diameters or changing the number of balls. Nevertheless, the micro pump can also work in high speed mode. A high back pressure up to 10 kPa was achieved at 500 rpm using a high speed DC motor, and an utmost flow rate up to 5 mL/min was reached. PMID:22574035
Simulations of peristaltic slip-flow of hydromagnetic bio-fluid in a curved channel
Ali, N.; Javid, K.; Sajid, M.
2016-02-01
The influence of slip and magnetic field on transport characteristics of a bio-fluid are analyzed in a curved channel. The problem is modeled in curvilinear coordinate system under the assumption that the wavelength of the peristaltic wave is larger in magnitude compared to the width of the channel. The resulting nonlinear boundary value problem (BVP) is solved using an implicit finite difference technique (FDT). The flow velocity, pressure rise per wavelength and stream function are illustrated through graphs for various values of rheological and geometrical parameters of the problem. The study reveals that a thin boundary layer exists at the channel wall for strong magnetic field. Moreover, small values of Weissenberg number counteract the curvature and make the velocity profile symmetric. It is also observed that pressure rise per wavelength in pumping region increases (decreases) by increasing magnetic field, Weissenberg number and curvature of the channel (slip parameter).
Effect of induced magnetic field on peristaltic flow of a micropolar fluid in an asymmetric channel
Shit, G C; Ng, E Y K; 10.1002/cnm.1397
2010-01-01
Of concern in this paper is an investigation of peristaltic transport of a physiological fluid in an asymmetric channel under long wave length and low-Reynolds number assumptions. The flow is assumed to be incompressible, viscous, electrically conducting micropolar fluid and the effect of induced magnetic field is taken into account. Exact analytical solutions obtained for the axial velocity, microrotation component, stream line pattern, magnetic force function, axial-induced magnetic field as well as the current density distribution across the channel. The flow phenomena for the pumping characteristics, trapping and reflux are also investigated. The results presented reveal that the velocity decreases with the increase of magnetic field as well as the coupling parameter. Moreover, the trapping fluid can be eliminated by the application of an external magnetic field. Thus, the study bears the promise of important applications in physiological systems.
Convective boundary conditions effect on peristaltic flow of a MHD Jeffery nanofluid
Kothandapani, M.; Prakash, J.
2016-03-01
This work is aimed at describing the influences of MHD, chemical reaction, thermal radiation and heat source/sink parameter on peristaltic flow of Jeffery nanofluids in a tapered asymmetric channel along with slip and convective boundary conditions. The governing equations of a nanofluid are first formulated and then simplified under long-wavelength and low-Reynolds number approaches. The equation of nanoparticles temperature and concentration is coupled; hence, homotopy perturbation method has been used to obtain the solutions of temperature and concentration of nanoparticles. Analytical solutions for axial velocity, stream function and pressure gradient have also constructed. Effects of various influential flow parameters have been pointed out through with help of the graphs. Analysis indicates that the temperature of nanofluids decreases for a given increase in heat transfer Biot number and chemical reaction parameter, but it possesses converse behavior in respect of mass transfer Biot number and heat source/sink parameter.
Non-Newtonian effects in the peristaltic flow of a Maxwell fluid
Tsiklauri, D
2001-01-01
We analyzed the effect of viscoelasticity on the dynamics of fluids in porous media by studying the flow of a Maxwell fluid in a circular tube, in which the flow is induced by a wave traveling on the tube wall. The present study investigates novelties brought about into the classic peristaltic mechanism by inclusion of non-Newtonian effects that are important, for example, for hydrocarbons. This problem has numerous applications in various branches of science, including stimulation of fluid flow in porous media under the effect of elastic waves. We have found that in the extreme non-Newtonian regime there is a possibility of a fluid flow in the direction {\\it opposite} to the propagation of the wave traveling on the tube wall.
Development of a Peristaltic Micropump for Bio-Medical Applications Based on Mini LIPCA
Thanh Tung Nguyen; My Pham; Nam Seo Goo
2008-01-01
This paper presents the design, fabrication, and experimental characterization of a peristaltic micropump. The micropump is composed of two layers fabricated from Polydimethylsiloxane (PDMS) material. The first layer has a rectangular channel and two valve seals. Three rectangular mini lightweight piezo-composite actuators are integrated in the second layer, and used as actuation parts.Two layers are bonded, and covered by two Polymethyl Methacrylate (PMMA) plates, which help increase the stiffness of the micropump.A maximum flow rate of 900 uL·min-1 and a maximum backpressure of 1.8 kPa are recorded when water is used as pump liquid. We measured the power consumption of the micropump. The micropump is found to be a prom- ising candidate for bio-medical application due to its bio-compatibility, portability, bidirectionality, and simple effective design.
Peristaltic motion of Johnson-Segalman fluid in a curved channel with slip conditions.
Sadia Hina
Full Text Available Slip effects on the peristaltic transport of Johnson-Segalman fluid through a curved channel have been addressed. The influence of wall properties is also analyzed. Long wavelength and low Reynolds number assumptions have been utilized in the mathematical formulation of the problem. The equations so formed have been solved numerically by shooting method through computational software Mathematica 8. In addition the analytic solution for small Weissenberg number (elastic parameter is computed through a regular perturbation method. An excellent agreement is noticed between the two solutions. The results indicate an increase in the magnitude of velocity with an intensification in the slip effect. Moreover the size and circulation of the trapped boluses increase with an increase in the slip parameter. Unlike the planar channel, the profiles of axial velocity are not symmetric about the central line of the channel.
Hayat, T. [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Department of Mathematics, King Abdulaziz University, P.O. Box 80257, Jeddah 21589 (Saudi Arabia); Nisar, Z. [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Ahmad, B. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Department of Mathematics, King Abdulaziz University, P.O. Box 80257, Jeddah 21589 (Saudi Arabia); Yasmin, H., E-mail: qau2011@gmail.com [Department of Mathematics, COMSATS Institute of Information Technology, G.T. Road, Wah Cantt 47040 (Pakistan)
2015-12-01
This paper is devoted to the magnetohydrodynamic (MHD) peristaltic transport of nanofluid in a channel with wall properties. Flow analysis is addressed in the presence of viscous dissipation, partial slip and Joule heating effects. Mathematical modelling also includes the salient features of Brownian motion and thermophoresis. Both analytic and numerical solutions are provided. Comparison between the solutions is shown in a very good agreement. Attention is focused to the Brownian motion parameter, thermophoresis parameter, Hartman number, Eckert number and Prandtl number. Influences of various parameters on skin friction coefficient, Nusselt and Sherwood numbers are also investigated. It is found that both the temperature and nanoparticles concentration are increasing functions of Brownian motion and thermophoresis parameters. - Highlights: • Temperature rises when Brownian motion and thermophoresis effects intensify. • Temperature profile increases when thermal slip parameter increases. • Concentration field is a decreasing function of concentration slip parameter. • Temperature decreases whereas concentration increases for Hartman number.
Peristaltic Transport of Prandtl-Eyring Liquid in a Convectively Heated Curved Channel.
Hayat, Tasawar; Bibi, Shahida; Alsaadi, Fuad; Rafiq, Maimona
2016-01-01
Here peristaltic activity for flow of a Prandtl-Eyring material is modeled and analyzed for curved geometry. Heat transfer analysis is studied using more generalized convective conditions. The channel walls satisfy complaint walls properties. Viscous dissipation in the thermal equation accounted. Unlike the previous studies is for uniform magnetic field on this topic, the radial applied magnetic field has been utilized in the problems development. Solutions for stream function (ψ), velocity (u), and temperature (θ) for small parameter β have been derived. The salient features of heat transfer coefficient Z and trapping are also discussed for various parameters of interest including magnetic field, curvature, material parameters of fluid, Brinkman, Biot and compliant wall properties. Main observations of present communication have been included in the conclusion section. PMID:27304458
Hayat, Tasawar; Nawaz, Sadaf; Alsaedi, Ahmed; Rafiq, Maimona
2016-01-01
Main objective of present study is to analyze the mixed convective peristaltic transport of water based nanofluids using five different nanoparticles i.e. (Al2O3, CuO, Cu, Ag and TiO2). Two thermal conductivity models namely the Maxwell's and Hamilton-Crosser's are used in this study. Hall and Joule heating effects are also given consideration. Convection boundary conditions are employed. Furthermore, viscous dissipation and heat generation/absorption are used to model the energy equation. Problem is simplified by employing lubrication approach. System of equations are solved numerically. Influence of pertinent parameters on the velocity and temperature are discussed. Also the heat transfer rate at the wall is observed for considered five nanofluids using the two phase models via graphs. PMID:27104596
This paper is devoted to the magnetohydrodynamic (MHD) peristaltic transport of nanofluid in a channel with wall properties. Flow analysis is addressed in the presence of viscous dissipation, partial slip and Joule heating effects. Mathematical modelling also includes the salient features of Brownian motion and thermophoresis. Both analytic and numerical solutions are provided. Comparison between the solutions is shown in a very good agreement. Attention is focused to the Brownian motion parameter, thermophoresis parameter, Hartman number, Eckert number and Prandtl number. Influences of various parameters on skin friction coefficient, Nusselt and Sherwood numbers are also investigated. It is found that both the temperature and nanoparticles concentration are increasing functions of Brownian motion and thermophoresis parameters. - Highlights: • Temperature rises when Brownian motion and thermophoresis effects intensify. • Temperature profile increases when thermal slip parameter increases. • Concentration field is a decreasing function of concentration slip parameter. • Temperature decreases whereas concentration increases for Hartman number
Peristaltic Pumping near Post-CME Supra-Arcade Current Sheets
Scott, Roger B; McKenzie, David E
2013-01-01
Measurements of temperature and density near supra-arcade current sheets suggest that plasma on unreconnected field lines may experience some degree of "pre-heating" and "pre-densification" prior to their reconnection. Models of patchy reconnection allow for heating and acceleration of plasma along reconnected field lines but do not offer a mechanism for transport of thermal energy across field lines. Here we present a model in which a reconnected flux tube retracts, deforming the surrounding layer of unreconnected field. The deformation creates constrictions that act as peristaltic pumps, driving plasma flow along affected field lines. Under certain circumstances these flows lead to shocks that can extend far out into the unreconnected field, altering the plasma properties in the affected region. These findings have direct implications for observations in the solar corona, particularly in regard to such phenomena as high temperatures near current sheets in eruptive solar flares and wakes seen in the form of ...
A Peristaltic Micro Pump Driven by a Rotating Motor with Magnetically Attracted Steel Balls
Zhaoying Zhou
2009-04-01
Full Text Available In this paper, we present a membrane peristaltic micro pump driven by a rotating motor with magnetically attracted steel balls for lab-on-a-chip applications. The fabrication process is based on standard soft lithography technology and bonding of a PDMS layer with a PMMA substrate. A linear flow rate range ~490 μL/min was obtained by simply varying the rotation speed of a DC motor, and a maximum back pressure of 592 Pa was achieved at a rotation speed of 43 rpm. The flow rate of the pump can also be adjusted by using steel balls with different diameters or changing the number of balls. Nevertheless, the micro pump can also work in high speed mode. A high back pressure up to 10 kPa was achieved at 500 rpm using a high speed DC motor, and an utmost flow rate up to 5 mL/min was reached.
Seok-Won Kang; Joe Fragala; Debjyoti Banerjee
2015-01-01
Bi-layer (Au-Si3N4) microcantilevers fabricated in an array were used to detect vapors of energetic materials such as explosives under ambient conditions. The changes in the bending response of each thermal bimorph (i.e., microcantilever) with changes in actuation currents were experimentally monitored by measuring the angle of the reflected ray from a laser source used to illuminate the gold nanocoating on the surface of silicon nitride microcantilevers in the absence and presence of a desig...
A novel peristaltic pump for portable microfluidic devices has been recently designed and fabricated. The operation principle is based on the peristaltic motion of eight elastic pumping channels that are occluded by a screw shaft. The screw shaft rotating inside the pumping channel unit has a spirally arranged projection which deforms and closes down the channels as a normally closed valve. While the shaft rotates, the pinched locations in the channels move either way according to the direction of rotation, squeezing out the fluid inside. It features unlimited and quantitative fluid feeding with a wide range of flow rates for one channel from 3.5 µL min−1 at 3 rpm to 280.2 µL min−1 at 180 rpm. It was demonstrated that pulsation can be drastically reduced by merging two anti-phase channels.
In this study the peristaltic motion of Oldroyd fluid in an asymmetric channel is investigated. Mathematical analysis has been carried out in the presence of an inclined magnetic field. Heat transfer is also taken into account. The physical problem is first modeled and then the analytical solutions of coupled equations are developed by regular perturbation method. Assumptions of long wavelength approximation are used. Effects of inclined magnetic field on the axial velocity and temperature are presented. Physical features of pertinent parameters such as wave number δ, Reynolds number Re, Weissenberg number Wi, Prandtl number Pr and Hartmann number M are also discussed graphically at the end of the paper. - Highlights: • This paper analyses heat transfer and inclined magnetic effects in peristaltic motion of Oldroyd fluid. • An asymmetric channel under long wavelength approximation is considered. • Regular perturbation method is used to find analytical solutions. • Effects of sundry parameters are presented through graphs
In the current study, sway of nanofluid on peristaltic transport of a hyperbolic tangent fluid model in the incidence of tending magnetic field has been argued. The governing equations of a nanofluid are first modeled and then simplified under lubrication approach. The coupled nonlinear equations of temperature and nano particle volume fraction are solved analytically using a homotopy perturbation technique. The analytical solution of the stream function and pressure gradient are carried out using perturbation technique. The graphical results of the problem under discussion are also being brought under consideration to see the behavior of various physical parameters. - Highlights: • The main motivation of this work is that we want to see the behavior of nanofluids in peristaltic flows. • In literature few articles are available on this, but no article is available in asymmetric channel on the new fluid model hyperbolic tangent fluid. • So we want to fill the gap in literature studying this
In the present study, we discuss the peristaltic flow of a Johnson—Segalman fluid in an endoscope. Perturbation, homotopy, and numerical solutions are found for the non-linear differential equation. The comparative study is also made to check the validity of the solutions. The expressions for pressure rise frictional forces, pressure gradient, and stream lines are presented to interpret the behavior of various physical quantities of the Johnson—Segalman fluid. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Misra, J. C.; Maiti, S.; Shit, G. C.
2010-01-01
The paper deals with a theoretical investigation of the peristaltic transport of a physiological fluid in a porous asymmetric channel under the action of a magnetic field. The stream function, pressure gradient and axial velocity are studied by using appropriate analytical and numerical techniques. Effects of different physical parameters such as permeability, phase difference, wave amplitude and magnetic parameter on the velocity, pumping characteristics, streamline pattern and trapping are ...
A. V. Ramana Kumari; G. Radhakrishnamacharya
2011-01-01
The effects of slip and elasticity of flexible walls on peristaltic transport of an incompressible viscous fluid in a two dimensional uniform channel, with heat transfer in the presence of magnetic field is investigated. Using long wavelength approximation, a perturbation solution has been obtained in terms of wall slope parameter and closed form expressions are derived for average velocity, temperature and heat transfer. The effects of various pertinent parameters on average velocity and hea...
T Hayat; Maryam Iqbal; Humaira Yasmin; Fuad E Alsaadi; Huijun Gao
2015-07-01
A mathematical model is developed to analyse the peristaltic flow of couple-stress fluid in an inclined asymmetric channel with convective conditions. Soret and Dufour and Hall effects are taken into account. Analysis has been carried out in a wave frame of reference. Expressions for velocity, pressure gradient, temperature and concentration are constructed. Pumping and trapping phenomena are examined. Impact of sundry parameters on the velocity, temperature and concentration is discussed.
Tripathi, Dharmendra; Anwar Bég, O
2013-11-01
Magnetic fields are increasingly being utilized in endoscopy and gastric transport control. In this regard, the present study investigates the influence of a transverse magnetic field in the transient peristaltic rheological transport. An electrically-conducting couple stress non-Newtonian model is employed to accurately simulate physiological fluids in peristaltic flow through a sinusoidally contracting channel of finite length. This model is designed for computing the intra-bolus oesophageal and intestinal pressures during the movement of food bolus in the digestive system under magneto-hydro-dynamic effects. Long wavelength and low Reynolds number approximations have been employed to reduce the governing equations from nonlinear to linear form, this being a valid approach for creeping flows which characterizes physiological dynamics. Analytical approximate solutions for axial velocity, transverse velocity, pressure gradient, local wall shear stress and volumetric flow rate are obtained for the non-dimensional conservation equations subject to appropriate boundary conditions. The effects of couple stress parameter and transverse magnetic field on the velocity profile, pressure distribution, local wall shear stress and the averaged flow rate are discussed with the aid of computational results. The comparative study of non-integral and integral number of waves propagating along the finite length channel is also presented. Magnetic field and non-Newtonian properties are found to strongly influence peristaltic transport. PMID:23911695
The influence of an endoscope on peristaltic flow of a Jeffrey fluid through the cylindrical cavity between concentric tubes with variable magnetic field has been investigated. The governing equations of two dimensional fluid have been simplified under the consideration of long wavelength and low Reynolds number approximation. Exact analytical calculations are carried out for the pressure gradient, velocity, pressure rise, friction force on the inner and outer tubes and shear stress. The effect of the non-dimensional wave amplitude, the variable magnetic field, the ratio of relaxation of retardation time, the radius ratio and the non-dimensional volume flow are analyzed theoretically and computed numerically. Comparison was made with the results obtained in the presence and absence of variable magnetic field and an endoscope. The results indicate that the effect of the non-dimensional wave amplitude, variable magnetic field, ratio of relaxation to retardation time, radius ratio and non-dimensional volume flow on peristaltic flow are very pronounced. - Highlights: • The peristaltic flow of a Jeffrey fluid through the cylindrical cavity between concentric tubes with variable magnetic field. • Mathematical modeling is carried out by utilizing long wavelength and low Reynolds number assumptions. • Closed form expressions for the entered parameters have been computed numerically
This paper presents a novel vibration-based piezoelectric energy harvester capable of passively tuning its resonant frequency to a wide range of frequencies. The device comprises a dual bimorph with a mass at its free end. A novel sliding mechanism, consisting of two oblique springs connected to the tip mass, is proposed to widen the resonance frequency of the device even to very low frequencies. The application of two oblique springs results in an additional stiffness and axial load that are introduced within the system, such that the resonance frequency of the device is now a function of both the stiffness and axial load associated with the spring forces. An operator can manually change the resonance frequency of the harvester just by small adjustments of the sliding mechanism. Further, the device allows one to tune the resonance frequency of the beam to match very low frequencies without the requirement of having a large proof mass. The analytical solution of an axially loaded cantilevered piezoelectric energy harvester with tip stiffness, using Euler–Bernoulli beam assumptions, is presented. A parametric case study is presented to demonstrate the performance of the device. (paper)
Adaptive Q control for Tapping-mode Nano-scanning Using a Piezo-actuated Bimorph Probe
Gunev, Ihsan; Karaman, Sertac; Basdogan, Cagatay
2012-01-01
A new approach, called Adaptive Q-control, for tapping-mode Atomic Force Microscopy (AFM) is introduced and implemented on a home-made AFM set-up utilizing a Laser Doppler Vibrometer (LDV) and a piezo-actuated bimorph probe. In the standard Q-control, the effective Q-factor of the scanning probe is adjusted prior to the scanning depending on the application. However, there is a trade-off in setting the effective Q-factor of an AFM probe. The Q-factor is either increased to reduce the tapping forces or decreased to increase the maximum achievable scan speed. Realizing these two benefits simultaneously using the standard Q-control is not possible. In adaptive Q-control, the Q-factor of the probe is set to an initial value as in standard Q-control, but then modified on the fly during scanning when necessary to achieve this goal. In this paper, we present the basic theory behind the adaptive Q-control, the electronics enabling the on-line modification of the probe's effective Q-factor, and the results of the expe...
Development and experimental testing of a peristaltic device actuated by a single shape-memory NiTi wire are described. The actuator is designed to radially shrink a compliant silicone pipe, and must work on a sustained basis at an actuation frequency that is higher than those typical of NiTi actuators. Four rigid, aluminum-made circular sectors are sitting along the pipe circumference and provide the required NiTi wire housing. The aluminum assembly acts as geometrical amplifier of the wire contraction and as heat sink required to dissipate the thermal energy of the wire during the cooling phase. We present and discuss the full experimental investigation of the actuator performance, measured in terms of its ability to reduce the pipe diameter, at a sustained frequency of 1.5 Hz. Moreover, we investigate how the diameter contraction is affected by various design parameters as well as actuation frequencies up to 4 Hz. We manage to make the NiTi wire work at 3% in strain, cyclically providing the designed pipe wall displacement. The actuator performance is found to decay approximately linearly with actuation frequencies up to 4 Hz. Also, the interface between the wire and the aluminum parts is found to be essential in defining the functional performance of the actuator. (paper)
Motion generation of peristaltic mobile robot with particle swarm optimization algorithm
Homma, Takahiro; Kamamichi, Norihiro
2015-03-01
In developments of robots, bio-mimetics is attracting attention, which is a technology for the design of the structure and function inspired from biological system. There are a lot of examples of bio-mimetics in robotics such as legged robots, flapping robots, insect-type robots, fish-type robots. In this study, we focus on the motion of earthworm and aim to develop a peristaltic mobile robot. The earthworm is a slender animal moving in soil. It has a segmented body, and each segment can be shorted and lengthened by muscular actions. It can move forward by traveling expanding motions of each segment backward. By mimicking the structure and motion of the earthworm, we can construct a robot with high locomotive performance against an irregular ground or a narrow space. In this paper, to investigate the motion analytically, a dynamical model is introduced, which consist of a series-connected multi-mass model. Simple periodic patterns which mimic the motions of earthworms are applied in an open-loop fashion, and the moving patterns are verified through numerical simulations. Furthermore, to generate efficient motion of the robot, a particle swarm optimization algorithm, one of the meta-heuristic optimization, is applied. The optimized results are investigated by comparing to simple periodic patterns.
Yo Tanaka
2014-05-01
Full Text Available Lab-on-a-chip technology is promising for the miniaturization of chemistry, biochemistry, and/or biology researchers looking to exploit the advantages of a microspace. To manipulate fluid on a microchip, on-chip pumps are indispensable. To date, there have been several types of on-chip pumps including pneumatic, electroactive, and magnetically driven. However these pumps introduce polymers, metals, and/or silicon to the microchip, and these materials have several disadvantages, including chemical or physical instability, or an inherent optical detection limit. To overcome/avoid these issues, glass has been one of the most commonly utilized materials for the production of multi-purpose integrated chemical systems. However, glass is very rigid, and it is difficult to incorporate pumps onto glass microchips. This paper reports the use of a very flexible, ultra-thin glass sheet (minimum thickness of a few micrometers to realize a pump installed on an entirely glass-based microchip. The pump is a peristaltic-type, composed of four serial valves sealing a cavity with two penetrate holes using ultra-thin glass sheet. By this pump, an on-chip circulating flow was demonstrated by directly observing fluid flow, visualized via polystyrene tracking particles. The flow rate was proportional to the pumping frequency, with a maximum flow rate of approximately 0.80 μL/min. This on-chip pump could likely be utilized in a wide range of applications which require the stability of a glass microchip.
Hall and ion slip effects on peristaltic flow and heat transfer analysis with Ohmic heating
S ASGHAR; Q HUSSAIN; T HAYAT; F ALSAADI
2014-01-01
The peristaltic transport of a magnetohydrodynamic (MHD) fluid is exam-ined for both symmetric and asymmetric channels. Hall and ion slip effects are taken into account. The heat transfer is analyzed by considering the effects of viscous and Ohmic dissipations. The relevant flow problems are first modeled, and then the closed form solutions are constructed under the assumptions of long wavelength and low Reynolds number. The solutions are analyzed through graphical illustration. It is noted that the velocity increases but the temperature decreases with the increases in the Hall and ion slip parameters. The axial pressure gradient is less in magnitude in the presence of Hall and ion slip currents. The Hall and ion slip effects are to decrease the maximum pres-sure against which peristalsis works as a pump. The free pumping flux decreases with the increases in the Hall and ion slip parameters. The increases in the Hall and ion slip parameters result in an increase in the size of the trapped bolus.
Pandey, S. K.; Chaube, M. K.
2011-09-01
This paper presents an analytical study of the MHD flow of a micropolar fluid through a porous medium induced by sinusoidal peristaltic waves traveling down the channel walls. Low Reynolds number and long wavelength approximations are applied to solve the non-linear problem in the closed form and expressions for axial velocity, pressure rise per wavelength, mechanical efficiency and stream function are obtained. The impacts of pertinent parameters on the aforementioned quantities are examined by plotting graphs on the basis of computational results. It is found that the pumping improves with Hartman number but degrades with permeability of the porous medium.
Fahad Abbasi
2016-01-01
Full Text Available This article addresses the peristaltic transport of Eyring-Prandtl fluid in an inclined asymmetric channel. Heat and mass transfer phenomena along with Soret and Dufour effects is analyzed. Effects of inclined magnetic field and Joule heating are also discussed. Long wavelength approximation is adopted. Numerical computations for flow quantities of interest are analyzed. It is found that the parabolic velocity profile tends to shift from center of the channel towards the channel walls in the case of opposing flow. Velocity and temperature decrease whereas concentration increases by increasing the non-Newtonian parameter. Further the dependence of magnetic field on the angle is quite significant
Safia AKRAM
2013-01-01
Full Text Available In this paper we have investigated the peristaltic flow of an incompressible six constant Jeffreys model of fluid in an asymmetric channel. The flow is investigated in a wave frame of reference moving with the velocity of the wave. We have modeled the governing equations of a two dimensional six constant Jeffreys model of fluid under long wave length and low Reynolds number approximation. The analytical and numerical solutions of the proposed problem are discussed. The expression for the pressure rise is calculated using numerical integration. The Graphical results are presented to interpret various physical parameters of interest.
Akbar, Noreen Sher; Raza, M; Ellahi, R
2016-07-01
The peristaltic flow of a copper oxide water fluid investigates the effects of heat generation and magnetic field in permeable tube is studied. The mathematical formulation is presented, the resulting equations are solved exactly. The obtained expressions for pressure gradient, pressure rise, temperature, velocity profile are described through graphs for various pertinent parameters. It is found that pressure gradient is reduce with enhancement of particle concentration and velocity profile is upturn, beside it is observed that temperature increases as more volume fraction of copper oxide. The streamlines are drawn for some physical quantities to discuss the trapping phenomenon. PMID:27208518
Misra, J C; Shit, G C; 10.1142/S0219519408002784
2010-01-01
The paper deals with a theoretical investigation of the peristaltic transport of a physiological fluid in a porous asymmetric channel under the action of a magnetic field. The stream function, pressure gradient and axial velocity are studied by using appropriate analytical and numerical techniques. Effects of different physical parameters such as permeability, phase difference, wave amplitude and magnetic parameter on the velocity, pumping characteristics, streamline pattern and trapping are investigated with particular emphasis. The computational results are presented in graphical form. The results are found to be in perfect agreement with those of a previous study carried out for a non-porous channel in the absence of a magnetic field.
F M Abbasi; A Alsaedi; T Hayat
2014-01-01
The present investigation addresses the simultaneous effects of heat and mass transfer in the mixed convection peristaltic flow of viscous fluid in an asymmetric channel. The channel walls exhibit the convective boundary conditions. In addition, the effects due to Soret and Dufour are taken into consideration. Resulting problems are solved for the series solutions. Numerical values of heat and mass transfer rates are displayed and studied. Results indicate that the concentration and temperature of the fluid increase whereas the mass transfer rate at the wall decreases with increase of the mass transfer Biot number. Furthermore, it is observed that the temperature decreases with the increase of the heat transfer Biot number.
The projected force–displacement capability of piezoelectric ceramic films in the 20–50 µm thickness range suggests that they are well suited to many micro-fluidic and micro-pneumatic applications. Furthermore when they are configured as bending actuators and operated at ∼ 1 V µm−1 they do not necessarily conform to the high-voltage, very low-displacement piezoelectric stereotype. Even so they are rarely found today in commercial micro-electromechanical devices, such as micro-pumps and micro-valves, and the main barriers to making them much more widely available would appear to be processing incompatibilities rather than commercial desirability. In particular, the issues associated with integration of these devices into MEMS at the production level are highly significant and they have perhaps received less attention in the mainstream than they deserve. This paper describes a fabrication route based on ultra-precision ceramic machining and full-wafer bonding for cost-effective batch scale production of thick film PZT bimorph micro-actuators and their integration with MEMS. The resulting actuators are pre-stressed (ceramic in compression) which gives them added performance, they are true bimorphs with bi-directional capability and they exhibit full bulk piezoelectric ceramic properties. The devices are designed to integrate with ancillary systems components using transfer-bonding techniques. The work forms part of the European Framework 6 Project 'Q2M—Quality to Micro'
Bagdasaryan, Gevorg Y.
2016-06-01
Full Text Available A comprehensive theoretical analysis of a dynamic thermo-ferro-electric pre-stressed bimorph energy harvester is performed. The analysis also takes into account pyroelectric and thermal expansion effects. The most general analytical expression for the energy conversation coefficients are presented for bi-layer. These coefficients we derive for more general situation when mechanical, electrical, thermal fields are present. We derive coefficients (transformation coefficients for sensing, actuating, and energy harvesting. As a particular case, we derive an analytical expression for the energy harvesting coefficient due to pyroelectric and thermal expansion effects in a rater general situation. This is a function of material properties, location of boundary conditions, vibration frequency, and in plane compressive/tensile follower force. Numerical simulations of the analytical results are presented. Effects of volume fraction, material properties, applied mechanical loads, and boundary conditions on the harvesting coefficients are introduced in the figures. The results for a cantilever and a simply-supported plate-layer are obtained as particular cases. The result for a low frequency (static system is obtained as a particular case by approaching the vibration frequency to zero. It is shown that volume fraction, material properties, plain compressive/tensile follower force, the location of the boundary conditions, and the vibrational frequency of the bimorph strongly influence the strain distribution, and this in effect influences the charge coefficient and the generation of energy. The proposed model can be extended to thermal energy harvesters of piezoelectric-shape memory alloy (SMA composites.
Kothandapani, M., E-mail: mkothandapani@gmail.com [Department of Mathematics, University College of Engineering Arni, (A Constituent College of Anna University Chennai), Arni 632326, Tamil Nadu (India); Prakash, J., E-mail: prakashjayavel@yahoo.co.in [Department of Mathematics, Arulmigu Meenakshi Amman College of Engineering, Vadamavandal 604410, Tamil Nadu (India)
2015-03-15
Theoretical analyses on the effect of radiation and MHD on the peristaltic flow of a nanofluid through a porous medium in a two dimensional tapered asymmetric channel has been made. The nanofluid is assumed to be electrically conducting in the presence of a uniform magnetic field. The transport equation accounts the both Brownian motion and thermophoresis along with the radiation reaction. The problem has been further simplified with the authentic assumptions of long wavelength and small Reynolds number. The analytical expressions obtained for the axial velocity, stream function, temperature field, nanoparticle fraction field and pressure gradient provide satisfactory explanation. Influence of various parameters on the flow characteristics have been discussed with the help of graphical results. The trapping phenomenon has also been discussed in detail. - Highlights: • Combine effect of thermal radiation and MHD on the peristaltic flow of a Newtonian nanofluid are discussed. • This work may be first attempt dealing the study of Newtonian nanofluid flow in the porous tapered asymmetric channel. • The velocity, stream function, temperature field and nanoparticle fraction field provide satisfactory explanation with help of graphs.
Theoretical analyses on the effect of radiation and MHD on the peristaltic flow of a nanofluid through a porous medium in a two dimensional tapered asymmetric channel has been made. The nanofluid is assumed to be electrically conducting in the presence of a uniform magnetic field. The transport equation accounts the both Brownian motion and thermophoresis along with the radiation reaction. The problem has been further simplified with the authentic assumptions of long wavelength and small Reynolds number. The analytical expressions obtained for the axial velocity, stream function, temperature field, nanoparticle fraction field and pressure gradient provide satisfactory explanation. Influence of various parameters on the flow characteristics have been discussed with the help of graphical results. The trapping phenomenon has also been discussed in detail. - Highlights: • Combine effect of thermal radiation and MHD on the peristaltic flow of a Newtonian nanofluid are discussed. • This work may be first attempt dealing the study of Newtonian nanofluid flow in the porous tapered asymmetric channel. • The velocity, stream function, temperature field and nanoparticle fraction field provide satisfactory explanation with help of graphs
K. Ramesh; M. Devakar
2015-01-01
The intention of this investigation is to study the effects of heat transfer and inclined magnetic field on the peristaltic flow of Williamson fluid in an asymmetric channel through porous medium. The governing two-dimensional equations are simplified under the assumption of long wavelength approximation. The simplified equations are solved for the stream function, temperature, and axial pressure gradient by using a regular perturbation method. The expression for pressure rise is computed numerically. The profiles of velocity, pressure gradient, temperature, heat transfer coefficient and stream function are sketched and interpreted for various embedded parameters and also the behavior of stream function for various wave forms is discussed through graphs. It is observed that the peristaltic velocity increases from porous medium to non-porous medium, the magnetic effects have increasing effect on the temperature, and the size of the trapped bolus decreases with the increasing of magnetic effects while the trend is reversed with the increasing of Darcy number. Moreover, limiting solutions of our problem are in close agreement with the corresponding results of the Newtonian fluid model.
Swarnalathamma, B. V.; Krishna, M. Veera
2016-05-01
In this paper, we discussed the theoretical and computational study of peristaltic hemodynamic flow of couple stress fluids through a porous medium under the influence of magnetic field with wall slip condition. Actually this study is motivated towards the physiological flow of the blood in the micro circulatory system by taking account of the particle size effect. We consider the Reynolds number is small enough and the wave length to diameter ratio is large enough to negate inertial effects. The governing equations for the couple stress fluid flow through porous medium based on stoke constitutive equations and Brinkman model. The exact solutions for axial velocity, pressure gradient, frictional force, stream function and mechanical efficiency are obtained analytically, its behaviour computationally discussed with reference to different physical parameters reflecting couple stress parameter, Hartmann number, permeability parameter, slip parameter as well as amplitude ratio on pumping characteristics and frictional force, stream lines pattern and trapping of peristaltic flow pattern are studied with particular emphasis making use of graphs.
Objective: To directly compare CT enterography (CTE) and MR enterography (MRE) without antiperistaltic agents. Materials/methods: 26 patients referred for CTE underwent CTE immediately followed by MRE without use of an anti-peristaltic agent. Each study was evaluated on a 10 point scale for exam quality, level of diagnostic confidence, and presence of Crohn's disease. Kappa analysis was performed to determine the degree of agreement between the CTE and MRE of each patient. Results: 25 patients completed the MRE. The quality of the CTEs was judged as excellent by both readers (reader 1 = average 9.5/10, reader 2 = average 9.1/10). The quality of the MREs was ranked lower than the CTEs by both readers (reader 1 = average 8.9/10, reader 2 = average 7.2/10), which was statistically significant (p < 0.05). The level of confidence in interpretation was not significantly different between CTE and MRE for reader 1 or 2 (p = 0.3). There was substantial agreement between readers for the presence or absence of Crohn's disease on both CTE (kappa = 0.75) and MRE (kappa = 0.67). Conclusion: MR enterography without anti-peristaltic agents results in high diagnostic confidence and excellent agreement for the presence of Crohn's disease.
Kang, Seok-Won; Fragala, Joe; Banerjee, Debjyoti
2015-01-01
Bi-layer (Au-Si₃N₄) microcantilevers fabricated in an array were used to detect vapors of energetic materials such as explosives under ambient conditions. The changes in the bending response of each thermal bimorph (i.e., microcantilever) with changes in actuation currents were experimentally monitored by measuring the angle of the reflected ray from a laser source used to illuminate the gold nanocoating on the surface of silicon nitride microcantilevers in the absence and presence of a designated combustible species. Experiments were performed to determine the signature response of this nano-calorimeter platform for each explosive material considered for this study. Numerical modeling was performed to predict the bending response of the microcantilevers for various explosive materials, species concentrations, and actuation currents. The experimental validation of the numerical predictions demonstrated that in the presence of different explosive or combustible materials, the microcantilevers exhibited unique trends in their bending responses with increasing values of the actuation current. PMID:26334276
This paper focuses on the design and validation of a fuzzy logic controller for the smart fin of a projectile. The hollow fin is actuated by a cantilevered piezoelectric bimorph that is completely enclosed within it. A linear model of the actuator and fin is identified experimentally by exciting the system using a chirp signal. A procedure for designing a genetic algorithm (GA)-based fuzzy logic controller for the fin is presented. The controller is validated using simulation and experimental testing that is conducted in the subsonic wind tunnel at the University of Nevada, Las Vegas (UNLV). Results show that the proposed controller accomplishes the desired fin angle control under various operating conditions
Kh. S. Mekheimer
2008-01-01
Full Text Available A serious pathological condition is encountered when some blood constituents deposited on the blood vessels get detached from the wall, join the blood stream again and form a clot. Study of the peristaltic transport of a micropolar fluid in an annular region is investigated under low Reynolds number and long wavelength approximations. We model a small artery as a tube having a sinusoidal wave travelling down its wall and a clot model inside it. Closed form solutions are obtained for the velocity and the microrotation components, as well as the stream function, and they contain new additional parameters, namely, δ, the height of the clot, N, the coupling number and m, the micropolar parameter. The pressure rise and friction force on the inner and the outer tubes have been discussed for various values of the physical parameters of interest.
Abbasi, F. M.; Hayat, T.; Alsaedi, A.
2015-05-01
Impact of applied magnetic field on the peristaltic transport of Carreau-Yasuda fluid in a curved conduit is analyzed in this article. Hall effects are also taken into consideration. Lubrication approach is utilized in problem formulation. Resulting nonlinear system is solved numerically. Results for axial velocity, pressure gradient, pressure rise per wavelength and stream function are obtained and studied graphically. Results revealed that for small values of curvature parameter the fluid velocity is not symmetric about the centerline. Also increase in the value of Hall parameter balances the magnetic influence of applied magnetic field by some extent. Further, the Carreau-Yasuda fluid possesses large size of trapped bolus when compared with the Newtonian fluid.
Abbasi, F.M., E-mail: abbasisarkar@gmail.com [Department of Mathematics, Comsats Institute of Information Technology, Islamabad 44000 (Pakistan); Hayat, T. [Department of Mathematics, Quaid-I-Azam University, 45320 Islamabad 44000 (Pakistan); Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Alsaedi, A. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)
2015-05-15
Impact of applied magnetic field on the peristaltic transport of Carreau–Yasuda fluid in a curved conduit is analyzed in this article. Hall effects are also taken into consideration. Lubrication approach is utilized in problem formulation. Resulting nonlinear system is solved numerically. Results for axial velocity, pressure gradient, pressure rise per wavelength and stream function are obtained and studied graphically. Results revealed that for small values of curvature parameter the fluid velocity is not symmetric about the centerline. Also increase in the value of Hall parameter balances the magnetic influence of applied magnetic field by some extent. Further, the Carreau–Yasuda fluid possesses large size of trapped bolus when compared with the Newtonian fluid.
The effects of both magnetic field and wall slip conditions on the peristaltic transport of a Newtonian fluid in an asymmetric channel are studied analytically and numerically. The channel asymmetry is generated by propagation of waves on the channel walls travelling with different amplitudes, phases but with the same speed. The long wavelength and low Reynolds number assumptions are considered in obtaining solution for the flow. The flow is investigated in a wave frame of reference moving with velocity of the wave. Closed form expressions have been obtained for the stream function and the axial velocity component in fixed frame. The effects of phase difference, Knudsen number and magnetic field on the pumping characteristics and velocity field are discussed. Several known results of interest are found to follow as particular cases of the solution of the problem considered
Hayat, T.; Rafiq, M.; Ahmad, B.
2016-07-01
This article aims to predict the effects of convective condition and particle deposition on peristaltic transport of Jeffrey fluid in a channel. The whole system is in a rotating frame of reference. The walls of channel are taken flexible. The fluid is electrically conducting in the presence of uniform magnetic field. Non-uniform heat source/sink parameter is also considered. Mass transfer with chemical reaction is considered. Relevant equations for the problems under consideration are first modeled and then simplified using lubrication approach. Resulting equations for stream function and temperature are solved exactly whereas mass transfer equation is solved numerically. Impacts of various involved parameters appearing in the solutions are carefully analyzed.
S. K. Pandey
2010-01-01
Full Text Available The paper presents an analytical investigation of the peristaltic transport of a viscous fluid under the influence of a magnetic field through a tube of finite length in a dimensionless form. The expressions of pressure gradient, volume flow rate, average volume flow rate and local wall shear stress have been obtained. The effects of the transverse magnetic field and electrical conductivity (i.e. the Hartmann number on the mechanical efficiency of a peristaltic pump have also been studied. The reflux phenomenon is also investigated. It is concluded, on the basis of the pressure distribution along the tubular length and pumping efficiency, that if the transverse magnetic field and the electric conductivity increase, the pumping machinery exerts more pressure for pushing the fluid forward. There is a linear relation between the averaged flow rate and the pressure applied across one wavelength that can restrain the flow due to peristalsis. It is found that there is a particular value of the averaged flow rate corresponding to a particular pressure that does not depend on the Hartmann number. Naming these values ‘critical values’, it is concluded that the pressure required for checking the flow increases with the Hartmann number above the critical value and decreases with it below the critical value. It is also inferred that magneto-hydrodynamic parameters make the fluid more prone to flow reversal. The conclusion applied to oesophageal swallowing reveals that normal water is easier to swallow than saline water. The latter is more prone to flow reversal. A significant difference between the propagation of the integral and non-integral number of waves along the tube is that pressure peaks are identical in the former and different in the latter cases.
Eldabe, Nabil T. M.; Bothaina M. Agoor; Heba Alame
2014-01-01
This paper is devoted to the study of the peristaltic motion of non-Newtonian fluid with heat and mass transfer through a porous medium in the channel under the effect of magnetic field. A modified Casson non-Newtonian constitutive model is employed for the transport fluid. A perturbation series’ method of solution of the stream function is discussed. The effects of various parameters of interest such as the magnetic parameter, Casson parameter, and permeability parameter on the velocity, pre...
C. Vasudev; U.Rajeswara Rao; M. V. Subba Reddy; G. Prabhakara Rao
2010-01-01
In this paper, we studied the effects of heat transfer and magnetic field on the peristaltic flow of a Jeffrey fluid through a porous medium in an asymmetric channel under the assumptions of long wavelength and low Reynolds number. Expressions for the velocity and pressure gradient are obtained analytically. The effects of Hartmann number, Darcy number, phase shift, Jeffrey fluid parameter and upper and lower wave amplitudes on the pumping characteristics and the temperature field are discuss...
Kendig, Derek M; Hurst, Norman R.; Bradley, Zachary L.; Mahavadi, Sunila; Kuemmerle, John F.; Lyall, Vijay; DeSimone, John; Murthy, Karnam S.; John R Grider
2014-01-01
Intraluminal nutrients in the gut affect the peristaltic reflex, although the mechanism is not well defined. Recent evidence supports the presence of taste receptors and their signaling components in enteroendocrine cells, although their function is unclear. This study aimed to determine if nutrients modify colonic motility through activation of taste receptors. Colonic sections were immunostained for the umami taste receptor T1R1/T1R3, which mediates the response to umami ligands, such as mo...
Seok-Won Kang
2015-08-01
Full Text Available Bi-layer (Au-Si3N4 microcantilevers fabricated in an array were used to detect vapors of energetic materials such as explosives under ambient conditions. The changes in the bending response of each thermal bimorph (i.e., microcantilever with changes in actuation currents were experimentally monitored by measuring the angle of the reflected ray from a laser source used to illuminate the gold nanocoating on the surface of silicon nitride microcantilevers in the absence and presence of a designated combustible species. Experiments were performed to determine the signature response of this nano-calorimeter platform for each explosive material considered for this study. Numerical modeling was performed to predict the bending response of the microcantilevers for various explosive materials, species concentrations, and actuation currents. The experimental validation of the numerical predictions demonstrated that in the presence of different explosive or combustible materials, the microcantilevers exhibited unique trends in their bending responses with increasing values of the actuation current.
Hayat, T.; Farooq, S.; Alsaedi, A.; Ahmad, B.
2016-08-01
The purpose of present investigation is to study the Hall and MHD effects on peristaltic flow of Carreau-Yasuda fluid in a convectively curved configuration. Thermal radiation, Soret and Dufour effects are also accounted. The channel walls comprised the no slip and compliant properties. Constitutive equations for mass, momentum, energy and concentration are first modeled in view of considered assumptions and then simplified under long wavelength and low Reynolds number approximation. Solution of the resulting system of equations is carried out via a regular perturbation technique. Physical behaviors of velocity, temperature, concentration and streamlines are discussed with the help of graphical representation.
A. Afsar Khan
2016-01-01
Full Text Available The peristaltic motion of a third order fluid due to asymmetric waves propagating on the sidewalls of a inclined asymmetric channel is discussed. The key features of the problem includes longwavelength and low-Reynolds number assumptions. A mathematical analysis has been carried out to investigate the effect of slip condition, variable viscosity and magnetohydrodynamics (MHD. Followed by the nondimensionalization of the nonlinear governing equations along with the nonlinear boundary conditions, a perturbation analysis is made. For the validity of the approximate solution, a numerical solution is obtained using the iterative collocation technique.
Nabil T. M. Eldabe
2014-01-01
Full Text Available This paper is devoted to the study of the peristaltic motion of non-Newtonian fluid with heat and mass transfer through a porous medium in the channel under the effect of magnetic field. A modified Casson non-Newtonian constitutive model is employed for the transport fluid. A perturbation series’ method of solution of the stream function is discussed. The effects of various parameters of interest such as the magnetic parameter, Casson parameter, and permeability parameter on the velocity, pressure rise, temperature, and concentration are discussed and illustrated graphically through a set of figures.
Abeer A. Shaaban
2013-01-01
Full Text Available We investigated the influence of heat and mass transfer on the peristaltic flow of magnetohydrodynamic Eyring-Powell fluid under low Reynolds number and long-wavelength approximation. The fluid flows between two infinite cylinders; the inner tube is uniform, rigid, and rest, while the outer flexible tube has a sinusoidal wave traveling down its wall. The governing equations are solved numerically using finite-difference technique. The velocity, temperature, and concentration distribution are obtained. The features of flow characteristics are analyzed by plotting graphs and discussed in detail.
This Letter discusses the influence of heat transfer and magnetic field on the peristaltic flow of Newtonian fluid in a vertical annulus under a zero Reynolds number and long wavelength approximation. The inner tube is uniform, rigid, while the outer tube has a sinusoidal wave traveling down its wall. The flow is investigated in a wave frame of reference moving with velocity of the wave. Numerical calculations are carried out for the pressure rise and frictional forces. The features of the flow characteristics are analyzed by plotting graphs and discussed in detail
C. Vasudev
2010-12-01
Full Text Available In this paper, we studied the effects of heat transfer and magnetic field on the peristaltic flow of a Jeffrey fluid through a porous medium in an asymmetric channel under the assumptions of long wavelength and low Reynolds number. Expressions for the velocity and pressure gradient are obtained analytically. The effects of Hartmann number, Darcy number, phase shift, Jeffrey fluid parameter and upper and lower wave amplitudes on the pumping characteristics and the temperature field are discussed through graphs in detail.
张瑶; 汤善治; 李明; 王立超; 高俊祥
2016-01-01
The third-generation synchrotron radiation sources are widely used in physics, chemistry, material science, etc. due to their light beams with high brilliance and low emittance. In order to eﬃciently utilize such light beams for scientific research, reflective mirrors with excellent figure quality are required. The reflective mirrors on the beamlines of synchrotron radiation sources consist of fixed polished shape mirrors and bendable mirrors. Bendable mirrors have been attracting the attention of the synchrotron radiation community because their curvatures can be varied to realize different focusing properties. Classical bendable mirrors are realized by applying mechanical moment at the ends of the mirror substrates. In this paper, we introduce a new concept of bendable mirrors, X-ray adaptive mirrors which are based on the adaptive optics technology and the properties of piezoelectric bimorph systems. X-ray adaptive mirrors exhibit many advantages over the classical bendable mirrors, such as mechanics-free, figure local corrections, and good focusing properties. The piezoelectric bimorph mirrors have been used in astronomy to correct the wavefront distortions introduced by atmospheric turbulence in real time. The piezoelectric bimorph mirror was first introduced into the field of synchrotron radiation by European Synchrotron Radiation Facility (ESRF) in the 1990s for making an X-ray reflective mirror. Compared with astronomy community, synchrotron radiation community is not interested in high-speed wavefront correction, but looking for the ultimate precision of the surface shape of piezoelectric bimorph mirror. In the second part of this paper, the usual structure and working principle are briefly described. Piezoelectric bimorph mirrors are laminated structures consisting of two strips of an active material such as zirconate lead titanate (PZT) and two faceplates of a reflecting material such as silicon. A discrete or continuous control electrode is located
In this paper, the effects of both initial stress, radially varying and gravity field on the peristaltic flow of an incompressible MHD Newtonian fluid in a vertical annulus have been studied under the assumption of long wavelength and low-Reynolds number. The analytical solution has been derived for the temperature, concentration and velocity. The results for velocity, concentration and temperature obtained in the analytical form have been evaluated numerically and discussed briefly. The effect of the non-dimensional wave amplitude, the coefficient of viscosity, Sort number, Schmidt number, initial stress, gravitational field and the dimensionless time-mean flow in the wave frame are analyzed theoretically and computed numerically. The expressions for pressure rise, temperature, concentration field, velocity and pressure gradient are sketched for various embedded parameters and interpreted. Numerical results are given and illustrated graphically in each case considered. Comparison was made with the results obtained in the presence and absence of initial stress and gravitational field. - Highlights: • Initial stress, radially varying and gravity field on the peristaltic flow of MHD Newtonian fluid. • The analytical solution for the temperature, concentration and velocity. • Effect of wave amplitude, viscosity, Sort number, Schmidt number, initial stress, gravitational in the wave frame
Abd-Alla, A.M., E-mail: mohmrr@yahoo.com [Mathematics Department, Faculty of Science, Taif University 888 (Saudi Arabia); Mathematics Department, Faculty of Science, Sohag (Egypt); Abo-Dahab, S.M. [Mathematics Department, Faculty of Science, Taif University 888 (Saudi Arabia); Mathematics Department, Faculty of Science, SVU, Qena 83523 (Egypt); El-Shahrany, H.D. [Mathematics Department, Faculty of Science, Taif University 888 (Saudi Arabia)
2014-08-01
In this paper, the effects of both initial stress, radially varying and gravity field on the peristaltic flow of an incompressible MHD Newtonian fluid in a vertical annulus have been studied under the assumption of long wavelength and low-Reynolds number. The analytical solution has been derived for the temperature, concentration and velocity. The results for velocity, concentration and temperature obtained in the analytical form have been evaluated numerically and discussed briefly. The effect of the non-dimensional wave amplitude, the coefficient of viscosity, Sort number, Schmidt number, initial stress, gravitational field and the dimensionless time-mean flow in the wave frame are analyzed theoretically and computed numerically. The expressions for pressure rise, temperature, concentration field, velocity and pressure gradient are sketched for various embedded parameters and interpreted. Numerical results are given and illustrated graphically in each case considered. Comparison was made with the results obtained in the presence and absence of initial stress and gravitational field. - Highlights: • Initial stress, radially varying and gravity field on the peristaltic flow of MHD Newtonian fluid. • The analytical solution for the temperature, concentration and velocity. • Effect of wave amplitude, viscosity, Sort number, Schmidt number, initial stress, gravitational in the wave frame.
Grand, David J., E-mail: dgrand@lifespan.org [Department of Diagnostic Imaging, Warren Alpert School of Medicine, Brown University, 593 Eddy St., Providence, RI 02903 (United States); Beland, Michael D. [Department of Diagnostic Imaging, Warren Alpert School of Medicine, Brown University, 593 Eddy St., Providence, RI 02903 (United States); Machan, Jason T. [Department of Orthopaedics and Surgery, Warren Alpert School of Medicine, Brown University, 593 Eddy St., Providence, RI 02903 (United States); Mayo-Smith, William W. [Department of Diagnostic Imaging, Warren Alpert School of Medicine, Brown University, 593 Eddy St., Providence, RI 02903 (United States)
2012-08-15
Objective: To directly compare CT enterography (CTE) and MR enterography (MRE) without antiperistaltic agents. Materials/methods: 26 patients referred for CTE underwent CTE immediately followed by MRE without use of an anti-peristaltic agent. Each study was evaluated on a 10 point scale for exam quality, level of diagnostic confidence, and presence of Crohn's disease. Kappa analysis was performed to determine the degree of agreement between the CTE and MRE of each patient. Results: 25 patients completed the MRE. The quality of the CTEs was judged as excellent by both readers (reader 1 = average 9.5/10, reader 2 = average 9.1/10). The quality of the MREs was ranked lower than the CTEs by both readers (reader 1 = average 8.9/10, reader 2 = average 7.2/10), which was statistically significant (p < 0.05). The level of confidence in interpretation was not significantly different between CTE and MRE for reader 1 or 2 (p = 0.3). There was substantial agreement between readers for the presence or absence of Crohn's disease on both CTE (kappa = 0.75) and MRE (kappa = 0.67). Conclusion: MR enterography without anti-peristaltic agents results in high diagnostic confidence and excellent agreement for the presence of Crohn's disease.
Abd-Alla, A. M.; Abo-Dahab, S. M.; El-Shahrany, H. D.
2014-08-01
In this paper, the effects of both initial stress, radially varying and gravity field on the peristaltic flow of an incompressible MHD Newtonian fluid in a vertical annulus have been studied under the assumption of long wavelength and low-Reynolds number. The analytical solution has been derived for the temperature, concentration and velocity. The results for velocity, concentration and temperature obtained in the analytical form have been evaluated numerically and discussed briefly. The effect of the non-dimensional wave amplitude, the coefficient of viscosity, Sort number, Schmidt number, initial stress, gravitational field and the dimensionless time-mean flow in the wave frame are analyzed theoretically and computed numerically. The expressions for pressure rise, temperature, concentration field, velocity and pressure gradient are sketched for various embedded parameters and interpreted. Numerical results are given and illustrated graphically in each case considered. Comparison was made with the results obtained in the presence and absence of initial stress and gravitational field.
Sewer Cleaning Inspection Robot Based on Peristaltic Walking%蠕动式污水管道清淤机器人
曹建树; 徐宝东; 鲁军; 刘强; 张义; 黄子茂
2014-01-01
采用模块化方法对污水管道清淤机器人中的管道清理单元、推进舱、阀组和控制单元等模块加以组合，并对其进行了总体方案设计，给出了机器人蠕动行走液压油路方案，分析了其蠕动行走过程。介绍了系统上、下位机联合控制方案，同时描述了下位机在控制系统中的功能及其对应程序流程。在此基础上，研制了一台污水管道清淤机器人，并对其进行了实验。结果表明：该机器人在现有方案下能够实现预定的设计目标，管道清理检测质量良好，可降低工人工作强度。%By combining pipe cleaning unit,propulsion module,valves and control with modularization method,the general scheme of a novel sewer cleaning inspection robot was designed. The peristaltic walking program based on hydraulic oil circuit of the ro-bot was given,and its peristaltic walking processes were analyzed. United control scheme of the system between host and lower comput-er was introduced. At the same time,the lower computer function in control system and its corresponding program flow were described. Upon this basis,a sewer cleaning inspection robot was developed and it was verified by testing experiments. The results show that the performances of robot have a good agreement with design aim in the scheme,and inspecting effect is good,which can reduce strength of worker.
Kothandapani, Munirathinam; Prakash, Jayavel
2014-10-31
In the present analytic thinking, we have modeled the governing equations of a two dimensional peristaltic transport of a Hyperbolic tangent nanofluid in the presence of a heat source/sink with the combined effects of thermal radiation and inclined magnetic field in a tapered asymmetric channel. The propagation of waves on the non-uniform walls to have different amplitudes and phase but the same wave speed is produced the tapered asymmetric channel. The equations of dimensionless temperature and nanoparticle concentration are solved analytically under assumptions of long wavelength and low Reynolds number. The governing equations of momentum of a hyperbolic tangent nanofluid for the tapered asymmetric channel have also been solved analytically using the regular perturbation method. The expression for average rise in pressure has been figured using numerical integrations. The effects of various physical parameters entering into the problem are discussed numerically and graphically. The phenomenon of trapping is also investigated. Furthermore, the received results show that the maximum pressure rise gets increased in case of non-Newtonian fluid when equated with Newtonian fluid. PMID:25373110
In this paper, the effects of both rotation and magnetic field of the peristaltic transport of a second-order fluid through a porous medium in a channel are studied analytically and computed numerically. The material is represented by the constitutive equations for a second-order fluid. Closed-form solutions under the consideration of long wavelength and low Reynolds number is presented. The analytical expressions for the pressure gradient, pressure rise, friction force, stream function, shear stress, and velocity are obtained in the physical domain. The effects of the non-dimensional wave amplitude, porosity, magnetic field, rotation, and the dimensionless time-mean flow in the wave frame are analyzed theoretically and computed numerically. Numerical results are given and illustrated graphically in each case considered. Comparison was made with the results obtained in the presence and absence of rotation, magnetic field, and porosity. The results indicate that the effects of the non-dimensional wave amplitude, porosity, magnetic field, rotation, and the dimensionless time-mean flow are very pronounced in the phenomena
Lee, Jung Chan; Park, Chan Young; Choi, Seong Wook; Kim, Jeong Chul; Lim, Ki Moo; Kim, Kyuseok; Jung, Sung Koo; Kwak, Young Ho; Shin, Sang Do; Jo, Ik Joon; Suh, Gil Joon; Min, Byoung Goo
2008-07-01
This study examined the treatment efficacy and the damage to the blood during hemoperfusion for treating paraquat poisoning using two blood pump mechanisms. Paraquat-poisoned animal models were prepared. A conventional hemodialysis machine, AK90, with a peristaltic roller pump and a cardiopulmonary support system, T-PLS, with a pulsatile blood pump were used during the animal experiments. A total of 12 dogs were treated with hemoperfusion using a charcoal column. Six dogs were treated with hemoperfusion and T-PLS, and the other six were treated with AK90. A paraquat dose of 30 mg/kg was administrated by an intravenous injection. Both pumps maintained blood flow rates of 125 mL/min measured by an ultrasonic flowmeter. For anticoagulation, heparin was administrated by an initial bolus (250 IU/kg) and a continuous injection (100 IU/kg/h). During the experiments, T-PLS and AK90 showed a similar toxin removal efficacy. Both devices decreased the plasma paraquat concentration to 10% of the initial dose within 4-h hemoperfusion. The two pumps showed similar hemolysis properties with acceptable levels. Although T-PLS was developed as a cardiopulmonary bypass system, it can also be used as a hemoperfusion treatment device. PMID:18638308
Rostgaard, J; Qvortrup, K; Poulsen, Steen Seier
1993-01-01
elements. By adding oxygenated fluorocarbon to glutaraldehyde perfusate-fixatives, enough oxygen is made accessible for cellular respiration as well as for the oxygen-consuming chemical reactions of glutaraldehyde with the tissue. Data on anaesthesia, operative manoeuvres, mechanical components of the......A new improved technique for whole-body perfusion-fixation of rats and other small animals is described. The driving force is a peristaltic pump which is feedback regulated by a pressure transducer that monitors the blood-perfusion pressure in the left ventricle of the heart. The primary perfusate-fixative...... is composed of a blood substitute--13.3% oxygenated fluorocarbon FC-75--in 0.05 M cacodylate buffer (pH 7.4) with a 2% glutaraldehyde. The secondary perfusate-fixative is composed of 2% glutaraldehyde in 0.05 M cacodylate buffer (pH 7.4) with 20 mM CaCl2. A double-barrelled, self-holding cannula is...
In the evaluation of the dysphagic patient, radiology is crucial as a technique for monitoring morphology and function. In particular, high-speed cineradiography can reveal a variety of pharyngeal dysfunctions. However, in the literature and in practice the difference between normal and abnormal function is not always clear. This monography is based on high-speed cineradiographies of swallowing in 75 non-dysphagic volunteers and in 189 dysphagic patients. The purpose was to study whether differences in bolus volumes, patient position, age and gender had any effects on the following parameters: the speed of the peristaltic wave and apex of the liquid barium bolus, the length of movement and the movement pattern of the hyoid bone and larynx, and epiglottic function. The study disclosed that the speed of the bolus, the anterior-superior movement and net movement of the hyoid bone increased significantly with larger bolus volumes. The position of the individual in relation to gravity significantly influenced the speed of peristalsis. In most of the measured parameters there were no differences between non-dysphagic and dysphagic individuals expect for differences in the intrapersonal variations and in the anterior-superior movement of the hyoid bone. In patients with pharyngeal dysfunction the initial stage of the elevation of the larynx was significantly lower than in patients without dysfunction. The approximation of the thyroid cartilage to the hyoid bone was significantly greater in individuals with normal epiglottic function than in those with epiglottic dysmobility. It is suggested that abnormal speed of peristalsis may be a mild form of dysfunction. Measurements of the aforementioned speed and movements can be done if bolus volume, age and position of the patient, film speed and magnifications factors are known. Hypotheses concerning epiglottic function and central control of swallowing are proposed. (au)
J·C·密斯拉; S·麦蒂; 海治
2012-01-01
研究食道中蠕动传输的流体力学.对任意的波形和任意的管道长度,建立起流变学流体蠕动传输的数学模型.用粘性流体的Ostwald-de Waele幂定律,描述非Newton流体的流动特性.解析公式化模型,详细且精确地给出食物块在食道中蠕动传输相关的一些重要性质.分析中应用了润滑理论,本研究特别适合于Reynolds数不大的情况.将食道看作环形的管道,通过食道壁周期性的收缩来传输食物块.就单个波和周期性收缩一组波的传播,研究与传输过程有关变量的变化,如压力、流速、食物颗粒轨迹以及流量等.局部压力的变化,对流变指数n有着高度的敏感性.研究结果清晰地表明,食物块在食道中蠕动传输时,Newton流体或流变学流体构成的连续流体,以组合波传播比大间隔单波传播,传输效率要高得多.%Fluid mechanical peristaltic transport through esophagus had been of concern. A mathematical model had been developed with an aim to study the peristaltic transport of a rheo-logical fluid for arbitrary wave shapes and tube lengths. The Ostwald-de Waele power law of viscous fluid was considered here to depict the non-Newtonian behaviour of the fluid. The model was formulated and analyzed with the specific aim of exploring some important information concerning the movement of food bolus through the esophagus. The analysis had been carried out by using lubrication theory. The study was particularly suitable for cases where the Reynolds number was small. The esophagus was treated as a circular tube through which the transport of food bolus takes places by periodic contraction of the esophageal wall. Variation of different variables concerned with the transport phenomena such as pressure, flow velocity, particle trajectory and reflux were investigated for a single wave as well as for a train of periodic peristaltic waves. Locally variable pressure was seen to be highly sensitive to the flow index n
A flexoelectric microelectromechanical system on silicon.
Bhaskar, Umesh Kumar; Banerjee, Nirupam; Abdollahi, Amir; Wang, Zhe; Schlom, Darrell G; Rijnders, Guus; Catalan, Gustau
2016-03-01
Flexoelectricity allows a dielectric material to polarize in response to a mechanical bending moment and, conversely, to bend in response to an electric field. Compared with piezoelectricity, flexoelectricity is a weak effect of little practical significance in bulk materials. However, the roles can be reversed at the nanoscale. Here, we demonstrate that flexoelectricity is a viable route to lead-free microelectromechanical and nanoelectromechanical systems. Specifically, we have fabricated a silicon-compatible thin-film cantilever actuator with a single flexoelectrically active layer of strontium titanate with a figure of merit (curvature divided by electric field) of 3.33 MV(-1), comparable to that of state-of-the-art piezoelectric bimorph cantilevers. PMID:26571008
D·特里帕蒂; M·K·乔伯; P·K·古泊塔; 吴承平
2011-01-01
The Stokes flow of micro-polar fluids by peristaltic pumping through the cylindrical tube under the effect of slip boundary condition was studied. The motion of wall was governed by the sinusoidal wave equation. Analytical and numerical solutions for axial velocity, micro-polar vector, stream function, pressure gradient, friction force and mechanical efficiency were obtained by using the lubrication theory. The impacts of emerging parameters such as coupling number, micro-polar parameter and slip parameter on pumping characteristic, friction force and trapping phenomena were depicted graphically. Numerical computation infers that more pressure requires for peristaltic pumping when coupling number is large while opposite behavior is found for micro-polar parameter and the slip parameter. The size of trapped bolus reduces with coupling number and micro-polar parameter whereas it blows up with slip parameter.%计及管道边界条件滑移的影响,研究微极流体蠕动泵,经由圆柱形管道输运的Stokes流动.壁面运动的控制方程为正弦波方程.使用润滑理论,得到了轴向速度、微转动向量、流函数、压力梯度、摩擦力和机械效率的解析数值解.用图形表示出构成参数,如像耦合参数、微极参数和表征蠕流泵特性的滑移参数、摩擦力和俘获现象的影响.数值计算表明,当耦合参数较大时,需要蠕动泵的压力更大,而微极参数和滑移参数正相反.俘获团块的大小随耦合参数和微极参数的减小而缩小,而随滑移参数的增大而缩小.
朱旭平
2015-01-01
New-process Mixiang Baijiu(liquor) is the innovative program in Changle Distillery which won the 2nd Prize of Guangdong Light Industry Science and Technology and State Light Industry Science&Technology Excellent Prize. The difference between new-process produc-tion and traditional production were as follows:in the new process (raw materials in liquid&solid separation loose state), water was added di-rectly in cooked raw materials, then caky starter was added for saccharfication and fermentation in the same fermenter;in traditional process (raw materials in gelatinized state), cooked raw materials were saccharified in saccharifying tank at first, then water was added for fermentation in the fermenter. The use of new-process often induced pipe obstruction because the commonly-used pneumatic drive membrane pump drained liquid during the transportation of liquid&solid separation loose raw materials. Changle Distillery used peristaltic pump to settle such prob-lem, which could achieve continuous production and completely solve pipeline blocking from steam machine to fermenter.%新工艺米香型白酒生产线属长乐烧企业的创新项目，该项目获广东轻工科技二等奖、获国家轻工科技优秀奖。新工艺与传统工艺最大的区别在于，前者是将熟化后的原料直接加水、加曲输入发酵罐糖化、发酵同罐进行，后者是先将熟化的原料在糖化槽中糖化后加水再输入发酵罐。前者物料为液固松散分离状态，后者为糊化状态，因此常用的气动隔膜泵输送液固松散分离状态物料时就常常将液体抽走，造成管道阻塞。长乐烧酒业在新工艺生产线上利用蠕动泵实现了将熟化原料加水混合物料轻松输入发酵罐的目标，解决了管道阻塞问题，达到了连续生产目的，彻底改变了蒸饭机至发酵罐间物料自动输送的难题。
Rotary Peristaltic Micro-Pump Based on the Nano-Magnetic Fluid%基于纳米磁性液体的旋转式蠕动微泵
吴健; 刘同冈; 张亮
2013-01-01
A rotary peristaltic micro-pump based on the nano-magnetic fluid was designed,which was composed of an upper substrate,a lower substrate and an elastic film positioned between the two substrates.A micro-channel was machined on each substrate,the magnetic fluid in the upper micro-channel was gathered by a permanent magnet to deform the elastic film in order to push the sample liquid in the lower micro-channel.Both micro-channels were designed with the ring structure to pump the liquid continuously.The operational result indicates that the flow rate and output pressure are the combination result of the positive pressure generated by the gradient magnetic field and the driving force produced by the moving magnetic field.When the rotational speed of the magnetic field is 6 r/min,the maximum output pressure and flow rate of the micro-pump are 1 600 Pa and 1.8 mL/min,respectively.%设计了一种基于纳米磁性液体的旋转式蠕动微泵.泵体由上、下基板和弹性薄膜组成,弹性薄膜位于上、下基板的中间位置.在上、下基板上分别加工出微型管道,上管道中的纳米磁性液体在磁场作用下压迫弹性薄膜变形,从而推动下管道中的液体流动,并且采用环形结构,实现连续泵送的目的.运行结果显示:泵送流量和泵送压力是梯度磁场产生的正压力与移动磁场产生的驱动力共同作用的结果.当磁场旋转速度达到6 r/min时,微泵产生的最大泵送压力达1 600 Pa,此时的流量为1.8 mL/min.
朱旭平
2015-01-01
新工艺米香型白酒生产线属长乐烧企业的创新项目，该项目获广东轻工科技二等奖、获国家轻工科技优秀奖。新工艺与传统工艺最大的区别在于，前者是将熟化后的原料直接加水、加曲输入发酵罐糖化、发酵同罐进行，后者是先将熟化的原料在糖化槽中糖化后加水再输入发酵罐。前者物料为液固松散分离状态，后者为糊化状态，因此常用的气动隔膜泵输送液固松散分离状态物料时就常常将液体抽走，造成管道阻塞。长乐烧酒业在新工艺生产线上利用蠕动泵实现了将熟化原料加水混合物料轻松输入发酵罐的目标，解决了管道阻塞问题，达到了连续生产目的，彻底改变了蒸饭机至发酵罐间物料自动输送的难题。%New-process Mixiang Baijiu(liquor) is the innovative program in Changle Distillery which won the 2nd Prize of Guangdong Light Industry Science and Technology and State Light Industry Science&Technology Excellent Prize. The difference between new-process produc-tion and traditional production were as follows:in the new process (raw materials in liquid&solid separation loose state), water was added di-rectly in cooked raw materials, then caky starter was added for saccharfication and fermentation in the same fermenter;in traditional process (raw materials in gelatinized state), cooked raw materials were saccharified in saccharifying tank at first, then water was added for fermentation in the fermenter. The use of new-process often induced pipe obstruction because the commonly-used pneumatic drive membrane pump drained liquid during the transportation of liquid&solid separation loose raw materials. Changle Distillery used peristaltic pump to settle such prob-lem, which could achieve continuous production and completely solve pipeline blocking from steam machine to fermenter.
Magnetic plucking of piezoelectric bimorphs for a wearable energy harvester
Pozzi, Michele
2016-04-01
A compact and low-profile energy harvester designed to be worn on the outside of the knee-joint is presented. Frequency up-conversion has been widely adopted in recent times to exploit the high frequency response of piezoelectric transducers within environments where only low frequencies are present. Contactless magnetic plucking is here introduced, in a variable reluctance framework, with the aim of improving the mechanical energy transfer into the transducers, which is sub-optimal with contact plucking. FEA and experiments were used to design an optimal arrangement of ferromagnetic teeth to interact with the magnets fixed to the piezoelectric beams. A prototype was made and extensively tested in a knee-joint simulator controlled with gait data available in the literature. Energy and power produced were measured for walking and running steps. A power management unit was developed using off-the-shelf components, permitting the generation of a stable and regulated supply of 26 mW at 3.3 V during walking. Record levels of rectified (unregulated) electrical power of over 50 and 70 mW per walking and running steps, respectively, were measured.
Single Crystal Bimorph Array Driven Deformable Mirrors Project
National Aeronautics and Space Administration — This Small Business Innovation Research (SBIR) Phase I project will research a novel deformable mirror design for NASA adaptive optics telescope applications . The...
Single Crystal Bimorph Array (SCBA) Driven Deformable Mirror (DM) Project
National Aeronautics and Space Administration — This Small Business Innovation Research (SBIR) Phase II project will research a novel deformable mirror design for NASA adaptive optics telescope applications. The...
Analytical solutions to flexural vibration of slender piezoelectric multilayer cantilevers
The modeling of vibration of piezoelectric cantilevers has often been based on passive cantilevers of a homogeneous material. Although piezoelectric cantilevers and passive cantilevers share certain characteristics, this method has caused confusion in incorporating the piezoelectric moment into the differential equation of motion. The extended Hamilton’s principle is a fundamental approach to modeling flexural vibration of multilayer piezoelectric cantilevers. Previous works demonstrated derivation of the differential equation of motion using this approach; however, proper analytical solutions were not reported. This was partly due to the fact that the differential equation derived by the extended Hamilton’s principle is a boundary-value problem with nonhomogeneous boundary conditions which cannot be solved by modal analysis. In the present study, an analytical solution to the boundary-value problem was obtained by transforming it into a new problem with homogeneous boundary conditions. After the transformation, modal analysis was used to solve the new boundary-value problem. The analytical solutions for unimorphs and bimorphs were verified with three-dimensional finite element analysis (FEA). Deflection profiles and frequency response functions under voltage, uniform pressure and tip force were compared. Discrepancies between the analytical results and FEA results were within 3.5%. Following model validation, parametric studies were conducted to investigate the effects of thickness of electrodes and piezoelectric layers, and the piezoelectric coupling coefficient d 31 on the performance of piezoelectric cantilever actuators. (paper)
Fabrication of a peristaltic micro pump with novel cascaded actuators
This paper presents the fabrication of an all-PDMS (polydimethylsiloxane) micro pump with novel cascaded actuators as dynamic valves. The micro pump consists of three pneumatic actuators in series and a micro fluidic channel connecting two fluidic inlet and outlet ports. The three-layer bonded pump structure is fabricated through a typical moulding process of PDMS and a simple heating process for the PDMS-to-PDMS bonding. The total size of the micro pump is 5 mm × 5 mm. The dynamic valve pattern of the single actuator is observed under various operational conditions of the square-wave input signal for the estimation of its volume stroke. The maximum volume stroke of the pneumatic actuator for liquid is about 85% of the volume of the liquid chamber. Three types of liquid-pumping tests are performed for characterization of the micro pump such as backpressure, frequency and viscous liquids. The flow rate of the de-ionized (DI) water is about 73.9 nl min−1 at zero backpressure. As the hydraulic difference between inlet and outlet ports increases, the flow rate gradually decreases. In the case of the frequency responses, the micro pump has the maximum flow rate of the DI water at 2 Hz. The viscosity-dependent flow rate of the working fluids is also observed
Evaluation of peristaltic micromixers for highly integrated microfluidic systems
Kim, Duckjong; Rho, Hoon Suk; Jambovane, Sachin; Shin, Soojeong; Hong, Jong Wook
2016-03-01
Microfluidic devices based on the multilayer soft lithography allow accurate manipulation of liquids, handling reagents at the sub-nanoliter level, and performing multiple reactions in parallel processors by adapting micromixers. Here, we have experimentally evaluated and compared several designs of micromixers and operating conditions to find design guidelines for the micromixers. We tested circular, triangular, and rectangular mixing loops and measured mixing performance according to the position and the width of the valves that drive nanoliters of fluids in the micrometer scale mixing loop. We found that the rectangular mixer is best for the applications of highly integrated microfluidic platforms in terms of the mixing performance and the space utilization. This study provides an improved understanding of the flow behaviors inside micromixers and design guidelines for micromixers that are critical to build higher order fluidic systems for the complicated parallel bio/chemical processes on a chip.
Esophageal contractions in type 3 achalasia esophagus: simultaneous or peristaltic?
Kim, Tae Ho; Patel, Nirali; Ledgerwood-Lee, Melissa; Mittal, Ravinder K
2016-05-01
Absence of peristalsis and impaired relaxation of lower esophageal sphincter are the hallmarks of achalasia esophagus. Based on the pressurization patterns, achalasia has been subdivided into three subtypes. The goal of our study was to evaluate the esophageal contraction pattern and bolus clearance in type 3 achalasia esophagus. High-resolution manometry (HRM) recordings of all patients diagnosed with achalasia esophagus in our center between the years 2011 and 2013 were reviewed. Recordings of 36 patients with type 3 achalasia were analyzed for the characteristics of swallow-induced "simultaneous esophageal contraction." The HRM impedance recordings of 14 additional patients with type 3 achalasia were analyzed for bolus clearance from the impedance recording. Finally, the HRM impedance along with intraluminal ultrasound imaging was conducted in six patients to further characterize the simultaneous esophageal contractions. Among 187 achalasia patients, 30 were type 1, 121 type 2, and 36 type 3. A total of 434 swallows evaluated in type 3 achalasia patients revealed that 95% of the swallow-induced contractions met criteria for simultaneous esophageal contraction, based on the onset of contraction. Interestingly, the peak and termination of the majority of simultaneous esophageal contractions were sequential. The HRM impedance revealed that 94% of the "simultaneous contractions" were associated with complete bolus clearance. Ultrasound image analysis revealed that baseline muscle thickness of patients in type 3 achalasia is larger than normal but the pattern of axial shortening is similar to that in normal subjects. The majority of esophageal contractions in type 3 achalasia are not true simultaneous contractions because the peak and termination of contraction are sequential and they are associated with complete bolus clearance. PMID:26950858
Evaluation of peristaltic micromixers for highly integrated microfluidic systems.
Kim, Duckjong; Rho, Hoon Suk; Jambovane, Sachin; Shin, Soojeong; Hong, Jong Wook
2016-03-01
Microfluidic devices based on the multilayer soft lithography allow accurate manipulation of liquids, handling reagents at the sub-nanoliter level, and performing multiple reactions in parallel processors by adapting micromixers. Here, we have experimentally evaluated and compared several designs of micromixers and operating conditions to find design guidelines for the micromixers. We tested circular, triangular, and rectangular mixing loops and measured mixing performance according to the position and the width of the valves that drive nanoliters of fluids in the micrometer scale mixing loop. We found that the rectangular mixer is best for the applications of highly integrated microfluidic platforms in terms of the mixing performance and the space utilization. This study provides an improved understanding of the flow behaviors inside micromixers and design guidelines for micromixers that are critical to build higher order fluidic systems for the complicated parallel bio/chemical processes on a chip. PMID:27036809
A peristaltic pump driven 89Zr separation module
Siikanen, J.; Peterson, M.; Tran, T.;
2012-01-01
To facilitate the separation of 89Zr produced in yttrium foils, an automated separation module was designed and assembled. The module separates more than 85% of produced 89Zr - activity in 3 g foils in less than 90 min. About 10 % remains in the dissolving vial. The quality of the separated 89Zr...
Vibration energy harvesting in railway tunnels with a wireless sensor node application
Wischke, Martin
2012-07-01
Vibration harvesting is a promising concept to prolong the lifetime of batterypowered stand-alone systems, or even to enable their energy-autonomy. This thesis focuses on ambient vibrations converted by electromechanical transducers into electricity. The final goal is energy scavenging from train-induced vibrations in railway tunnels. This is achieved via the development of a suitable harvester for this environment and the practical demonstration of a vibrationpowered wireless sensor node (WSN). At the beginning of this thesis, extensive vibration measurements were performed in several traffic tunnels. The obtained unique data set formed the basis for the design and test of several harvesters. The railway sleeper was chosen as usable harvester location. A shock-resistant double-side suspended piezoelectric cantilever was developed. Several cantilevers with different eigenfrequencies are combined in an array, creating a robust harvester with a broad bandwidth. A field test of 7 days in the Loetschbergbasis-tunnel verified that, on average the sufficient energy for powering a virtual wireless sensor node was scavenged. For application in a real WSN, the harvester array was scaled up to 10 cantilevers. The power management for the sensor node was developed concurrently. The central component is a power switch that monitors the energy level in the system's storage capacitor and only triggers the wireless interface when sufficient energy is available. Combined with a train detection circuit, the presented energy-autonomous WSN reliably reports every passing vehicle. In addition to the development of an energy-autonomous fully integrated WSN, this work investigates nonlinear properties of PZT ceramics. Consideration of the elastostriction and the electrostriction enables a more precises prediction of the tip displacement of a piezoelectric cantilever actuator. Further, the elastostriction is exploited to modify the resonance frequency of a bimorph cantilever. Basing
Implementation of an Algorithm for the Locomotion of Quadruped Robot with Bimorph Insect Leg.
Gabriel Duarte Gonçalves Pedro
2015-05-01
Full Text Available In the last decades the rising of higher processing power computers, together with more sophisticated robot actuators gave an impulse to the field of autonomous robots in robotics. The need to explore dirty, dangerous and difficult terrains is a suitable task for a robot, sparing a human from hazards of the environment. Even though wheeled robots have been used in great scale for explorations, its configuration has the downside of obstacle impediment and depending on the terrain its wheels can get stuck. The legged robot presents more versatility allowing him to surpass such obstacles in some cases. This article presents the continuation of the development of an quadruped robot with biomorphic insect leg.
Screen printed PZT/PZT thick film bimorph MEMS cantilever device for vibration energy harvesting
Xu, Ruichao; Lei, Anders; Dahl-Petersen, Christian; Hansen, K.; Guizzetti, M.; Birkelund, Karen; Thomsen, Erik Vilain; Hansen, Ole
2012-01-01
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...
Oberti, Sylvain; Bonnet, Henri; Fedrigo, Enrico; Ivanescu, Liviu; Kasper, Markus E.; Paufique, Jerome
2004-10-01
The accurate calibration of an AO system is fundamental in order to reach the top performance expected from design. To improve this aspect, we propose procedures for calibrating a curvature AO system in view of optimizing performances and robustness, based on the experience accumulated by the ESO AO team through the development of MACAO systems for VLTI and SINFONI. The approach maximizes the quality of the Interaction Matrix (IM) while maintaining the system in its linear regime and minimizing noise and bias on the measurement.
Interdomain region in single-crystal lithium niobate bimorph actuators produced by light annealing
Kubasov, I. V., E-mail: kubasov.ilya@gmail.com; Timshina, M. S.; Kiselev, D. A.; Malinkovich, M. D.; Bykov, A. S.; Parkhomenko, Yu. N. [National University of Science and Technology “MISiS” (Russian Federation)
2015-09-15
The interdomain region of a bidomain strucrture formed in 127°-cut lithium niobate single crystals using light annealing has been studied by optical and scanning probe microscopies. A periodic subdomain structure on the 180° macrodomain wall is visualized by piezoresponse force microscopy. The piezoresponse signal (polarization) is shown to be a power-law function of the domain width with an exponent n = 0.53.
MHD peristaltic motion of Johnson-Segalman fluid in a channel with compliant walls
Hayat, T. [Department of Mathematics, Quaid-i-Azam University, Islamabad 44000 (Pakistan)], E-mail: t_pensy@hotmail.com; Javed, Maryiam [Department of Mathematics, Quaid-i-Azam University, Islamabad 44000 (Pakistan); Asghar, S. [Department of Mathematical Sciences, COMSATS Institute of Information Technology, H-8, Islamabad (Pakistan)
2008-07-21
A mathematical model for magnetohydrodynamic (MHD) flow of a Johnson-Segalman fluid in a channel with compliant walls is analyzed. The flow is engendered due to sinusoidal waves on the channel walls. A series solution is developed for the case in which the amplitude ratio is small. Our computations show that the mean axial velocity of a Johnson-Segalman fluid is smaller than that of a viscous fluid. The variations of various interesting dimensionless parameters are graphed and discussed.
Peristaltic Motion of Power-Law Fluid with Heat and Mass Transfer
T.Hayat; S.Hina; Awatif A.Hendi
2011-01-01
@@ The effects of wall properties and heat and mass transfer on the peristalsis in a power-law fluid are investigated.The solutions for the stream function, temperature, concentration and heat transfer coefficient are obtained.The axial velocity, temperature and mass concentration are studied for different emerging parameters.