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B I O M E D I C A L A P P L I C A T I O N

Pulse-type drug delivery biochip

Micro Systems Lab. in AJOU UNIVERSITY


Fig. 1. The structure of the micropump	Fig. 2. The photograph of the micropump

Constant Delivery Thermopneumatic Valveless Micropump using surface tensions
Do Han Jun, Woo Young Sim, Sang Sik Yang and James Jungho Pak.
ABSTRACT
This project presents the fabrication and test of a thermnopneumatic micropump made of PDMS without membrane without valves for the application to transdermal drug delivery systems (DDS). The important objectives of the study on DDS are the reduction of side-effects due to the excessive dosage and the enhancement of the treatment effectiveness. They require precise control of the drug delivery amount so as to achieve the objectives. Several groups have made liquid dispensing actuators especially designed for DDS. They focused on the pump-like structures that can deliver drug continuously or measure the flow rate for the accurate drug delivery at the expense of the complication. In order to reduce the cost and simplify the structure without losing the accurateness, we propose a drug delivery micropump that injects a proper amount of drug by means of a bubble expansion by electric heating. The micropump consists of an inlet, an outlet, two air chambers and four air channels. The air chambers have ohmic heaters on the Pyrex glass substrate. Air channels connect the air chambers and the pump chamber. The one cycle of the operation includes drug filling and drug discharge. When we apply voltage to the heater, the air in the air chamber expands and pushes the drug in the pump chamber through the front air channels. Then, drug is discharged to the outlet by pneumatic pressure. If we turn off the heater, the air contracts and the expanded bubble is sucked into the air chamber through the rear air channels. Then, drug is supplied from the inlet into the pump chamber by the negative pneumatic pressure and the capillary attraction force. The total dimension of the micropump is 11.7 x 8.8 x 0.7 mm³. The discharge volume depends on the pump chamber size. The fabrication process is consist of the Ti/Au(500/1500 Å) deposition, pattern to make the micro heater and PDMS – glass bonding process. We test this pump operation for the input voltage of 3.5 V. The discharge volume of the micropump is calculated from the meniscus movement in the microchannel observed with a high speed video camera. The micropump discharges 110 nanoliters for 4 seconds. The experiment result agrees with the simulation result. We conclude that the proposed pump is feasible for the transdermal drug delivery.


(a)	(b)

(c)	(d)
Fig. 3. The photographs during the operation (a) t = 0 sec, (b) t = 1.5 sec, (c) t = 2.1 sec, (d) t = 4 sec

Related Papers

황성래, 전도한, 심우영, 김근영, 양상식, 박정호, “경피형 약물전달을 위한 나노리터급 열공압 마이크로펌프“, 제7회 한국 MEMS 학술대회 논문집, pp. 148-152, 2005. 04.
Sung Rae Hwang, Woo Young Sim, Do Han Jeon, Geun Young Kim, Sang Sik Yang and James Jungho Pak, “Fabrication and Test of a Submicroliter-level Thermopneumatic Micropump for Transdermal Drug Delivery”, Hawaii, 3rd Annual International IEEE EMBS Special Topic Conference on Microtechnologies in Medicine and Biology, 2005.05
전도한, 심우영, 양상식, 박정호, “표면 장력을 이용하여 정량 제어가 가능한 무밸브형 열공압 마이크로 펌프”, 제8회 한국 MEMS 학술대회 논문집, pp. 178-181, 2006. 04.
Do Han Jun, Woo Young Sim, Sang Sik Yang and James Jungho Pak, “Constant Delivery Thermopneumatic Valveless Micropump using surface tensions”, Singapore, Asia-Pacific Conference of Transducers and Micro-Nano Technology 2006, (2006.06.25-28)