3

M I C R O P U M P

Micro Thermopenumatic pump (Corrugated type)

Micro Systems Lab. in AJOU UNIVERSITY

A Fabrication and Drive Test of a Thermopneumatic Micropump with the Corrugated Diaphragm
O. C. Jeong and S. S. Yang.

ABSTRACT
This paper presents the fabrication of a micropump which consists of a thermopneumatic actuator with a corrugated diaphragm as the residual stress release structure and a pair of nozzle/diffuser. The dynamic deflection characteristic of the actuator and the performance of the micropump are obtained experimentally. Fig. 1 illustrates the cross-sectional view of the micropump. The upper part is the thermopneumatic actuator and the lower part consists of a pair of nozzle/diffuser and microchannels. The diaphragm is fabricated by the boron diffusion and the backside anisotropic etching with EPW (Ethylenediamine : Pyrocatechol : DI Water = 250 ㎖ : 40 g : 80 ㎖). The dimension of the diaphragm is 4000 × 4000 × 2 ㎛3. For the fabrication of the corrugation profiles, the frontside of wafer is etched by 14 ㎛. The corrugation arc length and the corrugation pitch are 310 ㎛ and 282 ㎛, respectively. For the deflection measurement of the corrugated diaphragm, the radius of the center flat zone is 210 ㎛. The Cr/Au (500 Å/1500 Å) heater is fabricated on #7740 Pyrex glass by deposition. The resistance of the Cr/Au heater is 72 Ω at room temperature. The processed silicon wafer is anodically bonded with the pyrex glass #7740 on which the Cr/Au heater deposited, an air cavity is formed. The anodic bonding is performed at 300 ℃ with 1200 V applied. Fig. 2 is the photograph of the fabricated thermopneumatic actuator with the corrugated diaphragm. Fig. 3 shows the measured center deflection of the diaphragm under the various applied voltage when the duty ratio is 40 %. A pair of nozzle/diffuser are fabricated by the anisotropic etch with EPW. The nozzle and diffuser have the same shape, but are fabricated in opposite direction. The two opening sizes and the length of the nozzle are 600 × 600 ㎛2, 100 × 100 ㎛2 and 330 ㎛, respectively. Fig. 4 shows the layout of the micropump and the microchannels for the measurement of the flow rate. To assemble the micropump, the silicon chip with the nozzle/diffuser is bonded on a pyrex glass substrate having the microholes, and the pyrex glass substrate is anodically bonded with a Si wafer having microchannels and reservoirs. Finally, the microactuator is bonded with the pyrex glass substrate using epoxy resin. The depth and width of the microchannels are 200 ㎛ and 700 ㎛, respectively. Fig. 5 shows the flow rate of the micropump measured when the applied voltage and the duty ratio are 20 V and 80 %, respectively. The maximum flow rate is about 2.3 ㎕/min at 5 ㎐. This thermopneumatic micropump with the corrugated diaphragm can be used to pump fluids containing cells or particles.

KOREAN ABSTRACT

Micro Systems Lab. in AJOU UNIVERSITY

Related Papers

O. C. Jeong, S. S. Yang, "Fabrication and Drive Test of a Thermopneumatic Micropump with the Corrugated Diaphragm," ICEE The International Conference on Electrical Engineering, pp. 902~905, Kyongju, Korea, July. 1998.
O. C. Jeong and S. S. Yang, "Fabrication of a Thermopneumatic Micropump with a Corrugated p+ Diaphragm," The 10th International Conference on Solid-State Sensors and Actuators (TRANSDUCERS '99), pp. 1780~1783, Sendai, Japan, June. 1999.
양상식, “Micro Pumps: Fabrication and Applications,” International Symposium on Micro/Nano Scale Mechanical Engineering, 서울대학교 정밀기계설계공동연구소, 1999.12.
양상식, 정옥찬, “Fabrication of a Thermopneumatic Micropump with Aluminum Flap valves," 제7회 한국반도체학술대회 논문집, pp.391-392, 2000.1.
Ok Chan Jeong, Sang Sik Yang,"Fabrication of a thermopneumatic microactuator with a corrugated p+ silicon diaphragm," Sensors and Actuators A, Volume 80, Issues 1, pp. 62-67, 1 , 2000. 3.
Ok Chan Jeong, Sang Sik Yang,"Fabrication and test of a thermopneumatic micropump with a corrugated p+ diaphragm," Sensors and Actuators A, Volume 83, Issues 1-3, pp. 249-255, 2000. 5.
O. C. Jeong, S. S. Yang, “Fabrication of a Thermopneumatic Micropump with Aluminum Flap valves," Journal of Korean Physical Society, Vol. 37, No. 6, pp.873-877, 2000. 12.