Basic Study on Functional Fluid Pump

2007 ◽  
Author(s):  
Tetsuhiro Tsukiji ◽  
Hiroki Sato ◽  
Kenta Suzuki
Keyword(s):  
Liquid Crystal ◽  
Electric Fields ◽  
Flow Channel ◽  
Maximum Pressure ◽  
Spiral Flow ◽  
Basic Study ◽  
Micro Pump ◽  
Three Phase ◽  
High Dielectric ◽  
Vibration Noise

This study contributes to the development of a micro-pump in micro-fabricated systems. Our micro-pump uses the dielectrophoresis of a liquid to eliminate vibration-noise, and it requires little or no maintenance. Three-phase alternating currents are used as rotation electric fields to rotate the liquid crystal using the dielectrophoresis property. The pump has spiral flow channel and was designed based on the rotation mechanism of the liquid crystal by using the three-phase alternating currents. The relation between the maximum pressure and the shape of the flow channel in the pump was investigated for various electric fields. Furthermore, pressure-flow rate characteristics of the pump were measured. The maximum pressure increased when we used a liquid crystal with a high dielectric constant for the constant voltage. We developed a micro-pump using the dielectrophoresis of liquid crystals. The size of our pump can be decreased by further research.

Electron microscopy studies of PZT ferroelectric film capacitor structures

1992 ◽  
Vol 50 (2) ◽  
pp. 1364-1365
Author(s):  
V. Kaushik ◽  
P. Maniar ◽  
J. Olowolafe ◽  
R. Jones ◽  
A. Campbell ◽  
...  
Keyword(s):  
Electric Fields ◽  
Sol Gel ◽  
Ferroelectric Material ◽  
Dielectric Constants ◽  
Dielectric Films ◽  
Lead Zirconium Titanate ◽  
Si Substrate ◽  
Film Capacitor ◽  
Pzt Films ◽  
High Dielectric

Lead zirconium titanate films (Pb (Zr,Ti) O3 or PZT) are being considered for potential application as dielectric films in memory technology due to their high dielectric constants. PZT is a ferroelectric material which shows spontaneous polarizability, reversible under applied electric fields. We report herein some results of TEM studies on thin film capacitor structures containing PZT films with platinum-titanium electrodes.The wafers had a stacked structure consisting of PZT/Pt/Ti/SiO2/Si substrate as shown in Figure 1. Platinum acts as electrode material and titanium is used to overcome the problem of platinum adhesion to the oxide layer. The PZT (0/20/80) films were deposited using a sol-gel method and the structure was annealed at 650°C and 800°C for 30 min in an oxygen ambient. XTEM imaging was done at 200KV with the electron beam parallel to <110> zone axis of silicon.Figure 2 shows the PZT and Pt layers only, since the structure had a tendency to peel off at the Ti-Pt interface during TEM sample preparation.

Numerical modelling of twisted nematic devices

1983 ◽  
Vol 309 (1507) ◽  
pp. 203-216 ◽  
Keyword(s):  
Liquid Crystal ◽  
Electric Fields ◽  
Low Cost ◽  
Three Dimensional ◽  
Physical Parameters ◽  
Crystal Layer ◽  
Liquid Crystal Layer ◽  
Chiral Nematic ◽  
Twisted Nematic ◽  
Three Dimensional Simulations

Over most of each active region in nematic and chiral nematic twist cells the motion and configuration of the liquid crystal layer does not vary appreciably with position parallel to the surfaces. In such laminar regions the statics, dynamics and optics ot the cell can be accurately simulated at low cost on a computer of moderate size, given the appropriate physical parameters. Methods and recent advances in simulation of laminar regions are reviewed. Bistable twist cells are simulated for illustration. Important problems of stability and edge effects in the presence of electric fields await solution with two- or three-dimensional simulations.

Helmholtz Resonance Based Micro Electrostatic Actuators for Compressible Gas Control: A Microjet Generator and a Gas Micro Pump

2010 ◽  
Vol 7 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Hanseup Kim ◽  
Khalil Najafi ◽  
Luis P. Bernal
Keyword(s):  
Total Power ◽  
Maximum Pressure ◽  
Air Velocity ◽  
Electrostatic Actuators ◽  
Helmholtz Resonance ◽  
Micro Pump ◽  
Resonant Behavior ◽  
In Series ◽  
Instantaneous Pressure ◽  
Gas Molecules

This paper reports Helmholtz-resonance based micro electrostatic actuators to control compressible gaseous fluids in the micro scale. Particularly, it discusses design, fabrication, and testing results of two electrostatic actuators: a micro jet generator and an integrated peristaltic multistage micro pump. These electrostatic actuators vibrate a micro membrane in a micro chamber at a high frequency (&gt;10 kHz), and easily induce the resonant behavior of compressible gases in the chamber. Such resonant behavior, often called the Helmholtz resonance, can repeatedly create instantaneous pressure in equilibrium between the inside and outside of the chamber and cause gas to rapidly exit the chamber, forming a collimated jet. The developed micro jet generator consists of multiple acoustic chambers in parallel; produces directional gas momentum from each chamber by utilizing the Helmholtz resonance; and collectively entrains nearby gas molecules to form a gas stream. The fabricated micro jet generator has a footprint of 1.6 × 1.6 cm2 and contains 25 acoustic micro thrusters. It operates using a 140 V and 70 kHz sinusoidal signal and produces a thrust of 55.6 μN, a maximum air velocity of 1.2 m/s, and consumes power of 3.11 mW. The developed micro pump consists of multiple acoustic chambers in series and produces a high total pressure by accumulating pressures across the multiple chambers, while maintaining high flow rates utilizing the fluidic resonance of each pumping chamber. The fabricated 18-stage pump produces the maximum air flow rate of 4.0 sccm and maximum pressure differentials of 17.5 kPa with total power consumptions of only 57 mW. Its total package volume is 25.1 × 19.1 × 1 mm3. It is notable that these electrostatic actuators, with their actuation membranes, acoustic chambers, fluidic channels, and micro valves, are fabricated into a single silicon chip by developing low temperature wafer bonding techniques to protect the polymer structures inside.

scholarly journals Capillary Flows of Nematic Liquid Crystal

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1029
Author(s):  
Dina V. Shmeliova ◽  
Sergey V. Pasechnik ◽  
Semen S. Kharlamov ◽  
Alexandre V. Zakharov ◽  
Eugeny P. Pozhidaev ◽  
...  
Keyword(s):  
Contact Angle ◽  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Electric Fields ◽  
Capillary Flow ◽  
Capillary Rise ◽  
Vertical Plane ◽  
Treatment Technique ◽  
Photo Alignment ◽  
Wetting Process

In this paper we report the new experimental results on the rise of a liquid crystal in flat capillaries with inner photosensitive surfaces. The capillaries with different surface orientations were prepared by the use of the photo-alignment technique. Such a surface treatment makes it possible to eliminate the noncontrollable influence of a nanorelief on the wetting process, which takes place in the rubbing treatment technique previously used in similar experiments. The dynamics of the capillary rise of a nematic liquid crystal 5CB (4-cyano-4′-pentylbiphenyl) in vertical plane capillaries with photo-aligned substrates were studied for the first time. It was found that the stationary value of a contact angle weakly depends on the direction of a planar surface orientation relative to the direction of a capillary rise. It has been shown that the application of strong electric fields resulted in a decreasing of the contact angle. The results, obtained for the nematic liquid crystal, are compared with the results of an investigation of the capillary flow in a shock-free ferroelectric smectic phase.

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