An electrostatic microvalve for pneumatic control of microfluidic systems

An electrostatic microvalve for pneumatic control of microfluidic devices is presented. The valve consists of several, individually manufactured pieces assembled to form a microvalve. The unique feature is its ability to be integrated with microfluidic systems. The valve was manufactured by depositing a thin chrome layer on poly(methyl methacrylate). A copper foil was used as a flexible membrane. When a voltage was applied between the chrome and the copper foil, the electrostatic force pulled the foil closed against the chrome and stopped the airflow. Parylene C was selected as a dielectric to prevent a short circuit between electrodes. It was determined through testing that a 6 mu m parylene layer with a 58 mu m cavity depth provided the best combination of a low closing voltage and a high flowrate. These valves worked at pressures up to 40 kPa with an average closing voltage of 680 V, and an average flowrate of 1.05 mL min(-1). Tests showed that it may be able to function as a flowrate control valve at pressures greater than 40 kPa. Dielectric charging occurred in the valve. Switching the control voltage polarity with each actuation delayed the onset of dielectric charging. The valve was used to pneumatically control flow in a simplified microfluidic device.