A planar PDMS micropump using in-contact minimized-leakage check valves

Abstract

We present a micropump with a simple planar design featuring compliant in-contact check valves in a single layer, which allows for a simple structure and easy system integration. The micropump, based on poly(dimethylsiloxane) (PDMS), primarily consists of a pneumatically driven thin membrane, a pump chamber, and two in-plane check valves. The pair of check valves is based on an in-contact flap-stopper configuration and is able to minimize leakage flow, greatly enhancing the reliability and performance of the micropump. Systematic experimental characterization of the micropump has been performed in terms of the frequency response of the pumping flow rate with respect to factors including device geometry (e.g. chamber height) and operating parameters (e.g. pneumatic driving pressure and backpressure). The results demonstrate that this micropump is capable of reliably generating a maximum flow rate of 41 μL min^-1 and operating against a high backpressure of up to 25 kPa. In addition, a lumped-parameter theoretical model for the planar micropump is also developed for accurate analysis of the device behavior. These results demonstrate the capability of this micropump for diverse applications in lab-on-a-chip systems.

Figure 1

Schematic of the micropump design integrating two planar in-contact check valves and pump chamber into one single layer.

Figure 2

The micropump fabrication process. (a) Fabrication of the PDMS functional layer by use of the clamping method. (b) Retrieval of the PDMS functional layer from the SU-8 mold (a gap exists between the flap and stopper). (c) Manipulation of the flap to make it in contact with the stopper. (d) Image of a check valve with in-contact flap and stopper. (e) Image of a packaged micropump device.

Figure 3

Schematic of the micropump experimental setup.

Figure 4

Schematic of the dynamic model for the planar micropump.

Figure 5

Characterization of the in-contact check valve in terms of its forward and backward flow rates as a function of the pressure drops. The leakage indicated by the backward flow at reverse pressures is negligible.

Figure 6

Measured and simulated pumping flow rate as a function of the driving frequency for varying pneumatic pressures.

Figure 7

Measured and simulated pumping flow rate as a function of the driving frequency for different pump-chamber heights.

Figure 8

Measured pumping flow rate as a function of the backpressures at varying frequencies.