A piezoelectrically-driven high flow rate axial polymer microvalve with solid hydraulic amplification

We report a piezoelectrically-driven and hydraulically-amplified axial polymer microvalve. The microvalve is normally open, and is fabricated and assembled primarily with stereolithographically fabricated polymer components. An incompressible elastomer is used as a solid hydraulic medium to convert the small axial displacement of a piezoelectric actuator into a large valve head stroke while maintaining a large blocking force. Also, the axial design of the microvalve enables densely-packed valve arrays. One application of this microvalve is in pneumatic tactile displays, some of which require operation against gas pressures up to approximately 90 kPa and switching speeds between 1-200 Hz. The current valve design has a maximum static hydraulic amplification ratio of 5 at 30 V driving voltage and a maximum valve head stroke of 37 mum at 150 V. Under a 94.4 kPa differential pressure, the flow rate of the valve and the closing voltage measure 785 mL/min and 150 V, respectively. In addition, the function of the microvalve as an on-off switch for a pneumatic microbubble tactile actuator is demonstrated.