An active valve incorporated into a microchip using a high strain electroactive polymer

Recently, various kinds of microvalves have been developed in the field of micro total analysis systems. Most are pneumatic or piezo electric valves, which require significant space on a microchip and hence make the system complicated. This study reports the use of an electroactive polymer-based microvalve that occupies only a small space on a microchip. An electroactive polymer membrane sandwiched between soft electrode sheets was placed on a dome-shaped diaphragm. The polymer actuator was installed in a glass microchip and the valve function was demonstrated. First, the displacement of the diaphragm was measured without fluid, and sufficient displacement (over 50 μm) was obtained for valve closing. Second, flow in a linear microchannel was stopped and then restarted by the valve. The flow in the microchannel produced by the constant pressure from a microfluidic controller (1.0 kPa) was completely stopped by applying a 50 V/μm electric field. This valve functioned well at pressures up to 4.0 kPa. The response time was about 0.7 s, similar to the time required for piezo electric actuator valves in channels of this size. This type of valve is very suitable for portable devices filed because of its compactness.