Hyun-Hoo Kim

Design and Modeling of Piezoelectric Pump for Microfluid Devices

Recently, there has been increased incessantly an interest in research area on microfluidic pump for electronic and biological applications. The proposed pump takes an unobtrusive operation into the simple displacing mechanism using peristaltic traveling waves without the physical moving valves. However, this piezopump makes up a radical design, based on the operation of the stator on the piezoelectric motor. The ATILA simulation performs to estimate the operating frequency of the vibrating wave mode, and optimize the design conditions of piezopump such as pump structure, elastic materials, piezoelectric ceramics, and z-displacement on the elastic traveling wave of piezopump. The best measured value of the pumping rate is about 118 μ l/min under the following parameters: 4-wave mode, the operating frequency of 50 kHz and the peak voltage of 200 V.

Design and Characteristics of Bar Type Piezoelectric Micropump

Micropump is very useful component in micro/nano fluidics and bioMEMS applications. Using the flexural vibration mode of PZT bar, a piezopump is successfully made. The PZT bar is polarized along the thickness direction. The proposed structure for the piezo-pump consists of the input and output ports the piezoelectric ceramic actuator, the actuator support, and the diaphragm. The traveling flexural wave along the bar is obtained by dividing two standing waves which are temporally and spatially phase shifted by 90 degrees from each other. Fluid is drawn into a forming chamber, eventually the forming chamber closes trapping the fluid therein. Components of piezopump were made, assembled, and tested to validate the concepts of the proposed pump and confirm the simulation results.

The performances of piezoelectric transformer for fluorescent T5 lamp

The properties of circular type piezoelectric transformer for fluorescent T5 lamp are investigated as a function of area ratio of input part to output part. From the simulation result using FEM, as the area ratio increases, the voltage step-up ratio increases linearly. The voltage step-up ratio of output to input is about 1.6 when the area ratio is about 2. The new ballast using piezoelectric transformer is the type of series resonant half bridge inverter. As the results of performance test, when the input voltage is 220 V rms , the step-up ratio is about 1.6 for lighting the lamp. Also, lamp current and output power are 150 mA and about 26 W in steady state, respectively. The efficiency is about 93 %. It is concluded that the PT fabricated in this study is available to the ballast for T5 lamp.

The Design and Characterization of Ultrasonic Motor for Optical Zooming of Camera in Mobile Phones

In this paper, the design and characteristics of a p-shaped ultrasonic motor which is applicable to optical zoom operation of lens system for mobile phone are investigated. Its design and simulation of performances are carried out by FEM (finite element method) commercial software. As a simulation result, by applying voltage with single phase, a combined vibration is produced at the surface of an arm of stator. The prototype of motor is fabricated and its outer size is 8 * 4 * 2 mm3 including the cylindrical steel rod of 2 mm in diameter as rotor. The motor exhibits a maximum speed of 500 rpm and a power consumption of 0.3 W when driven at 20 Vpp and 64 kHz.

The Dielectric and Piezoelectric Properties of yPb(Zr x Ti 1−x )O 3 -(1-y)Pb(Mn 1/3 Nb 1/3 Sb 1/3 )O 3 Ceramics

The piezoelectric and dielectric properties as functions of x and y in yPb(Zr x Ti 1 m x )O 3 -(1-y)Pb(Mn 1/3 Nb 1/3 Sb 1/3 )O 3 ceramics are studied. As the results, in 0.95Pb(Zr x Ti 1 m x )O 3 -0.05Pb(Mn 1/3 Nb 1/3 Sb 1/3 )O 3 ceramic with x=0.505, which is MPB, the values of k p , d 33 , and l 33 T / l 0 are maximized, on the other hand Q m is minimized. Curie temperature of the ceramic is measured to be 350 °C by DTA. Also, the MPB assumes to be x=0.5 in 0.9Pb(Zr x Ti 1 m x )O 3 -0.1Pb(Mn 1/3 Nb 1/3 Sb 1/3 )O 3 ceramic.

An Analysis of the Resonance Characteristics of a Traveling Wave Type Ultrasonic Motor by Applying a Normal Force and Input Voltage

Piezoelectric ceramics, constituting an active element, make a stator vibrate generating a rotational force in ultrasonic motors. In the drive of ultrasonic motors, many factors exist that can affect the resonance characteristics of piezoelectric ceramics. For example, those factors are the bonding conditions with the elastic body, the magnitude of the electric field, the normal force for the frictional drive, the emission of heat due to vibration and friction, and so on. Therefore, it is important to properly research the inclination for variation of piezoelectric ceramics in the circumstance where complex elements are involved. In this paper, we focus on the analysis of the resonance characteristics of an ultrasonic motor due to the magnitude of the input voltage and normal force.

PZT-PMN Ceramics for Large Displacement Piezoelectric Devices

Piezoelectric and dielectric properties as functions of x and y mole ratio in yPb(ZrxTil-x)O(1-y)Pb(Mn1/3/Nb/2/3/)O, ceramics, PZT-PMN, are investigated for large displacement piezoelectric devices. From the experimental results, when y is 0.95 and x is 0.505, the piezoelectric and dielectric properties are maximum, that is, electromechanical coupling coefficient(kp), piezoelectric strain constant(d33/), permittivity(33/T//0/), and Curie temperature are 58 %, 272 pC/N, 1520 and about 350, respectively. Also, when y is 0.90 and x is 0.50, their properties are 56 %, 242 pC/N, 1220, and 290, respectively. As MgO dopant is added from 0 wt% to 1 wt%, kp increases to 63 % and Qm decreases to 500 at the MgO dopant of 0.1 wt%, and then kp decreases to 57 % as MgO is added.

RF Bias Effect of ITO Thin Films Reactively Sputtered on PET Substrates at Room Temperature

ITO films were deposited on polyethylene terephthalate substrate by a dc reactive magnetron sputtering using rf bias without substrate heater and post-deposition thermal treatment. The dependency of rf substrate bias on plasma sputter processing was investigated to control energetic particles and improve ITO film properties. The substrate was applied negative rf bias voltage from 0 to -80 V. The composition of indium, tin, and oxygen atoms is strongly depended on the rf substrate bias. Oxygen deficiency is the highest at rf bias of -20 V. The electrical and optical properties of ITO films also are dominated obviously by negative rf bias.

A Valveless Piezoelectric Micro-Pump Using Peristaltic Motion of Two Sided Disk Type Vibrator

Piezoelectric micro-pump should contain the physical running parts like check valves for acquiring the unilateral motion of fluid from the alternating motion of actuators. But the check valves raise many problems such as abrasion or exhaustive destruction by the recursive mechanical displacement. And the performances of micro pump are deteriorated by them. To solve these problems, we propose a novel type piezoelectric valveless micro-pump using peristaltic motion due to the travelling wave excitation. Proposed pump model consists of two piezoelectric ceramic plates, elastic metal body, caps for covering flow path, rubber rings for tight sealing and disk springs for the pressurization of pump body. The FEM simulation analysis of the proposed pump model was carried out to verify its operation mechanism. And a prototype pump was fabricated and evaluated to validate the proposed concepts. Maximum back pressure was 0.97kPa and flow rate was 640μl/min under 130Vrms, 67.5kHz of driving voltage.

Design of a Piezoelectric Pump Using No Physically Moving Components

Using the extensional vibration mode of PZT ring, a piezopump is successfully made. The PZT ring is polarized with thickness direction. The traveling extensional wave along the circumference of the ring is obtained by dividing two standing waves which are temporally and spatially phase shifted by 90 degrees from each other. The proposed piezopump is consisted of coaxial cylindrical shells that are bonded piezoelectric ceramic ring. The pump takes an unobtrusive operation into the simple displacing mechanism using peristaltic traveling waves without the physical moving parts. The finite elements analysis on the proposed pump model is carried out to verify its operation principle and design by the commercial FEM software. Components of piezopump were made, assembled, and tested to validate the concepts of the proposed pump and confirm the simulation results. The performance of the proposed piezopump is about 580 μ l/min in flow rate with the highest pressure level of 0.85 kPa, when the driving voltage is 150 V p , 57 kHz.