An electrostatic microvalve for pneumatic control of microfluidic systems

• Published in: Journal of micromechanics and microengineering 2012-02, Vol.22 (2), p.25019-9
• Main Authors: Anjewierden, Douglas, Liddiard, Gregory A, Gale, Bruce K
• Format: Article
• Language: English
• Subjects: Applied fluid mechanics; Applied sciences; Charging; Devices; Dielectrics; Drives; Electric potential; electrostatic microvalve microfluidics MEMS; Electrostatics; Exact sciences and technology; Fluid dynamics; Fluidics; Foils; Fundamental areas of phenomenology (including applications); Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mechanical engineering. Machine design; Mechanical instruments, equipment and techniques; Microfluidics; Micromechanical devices and systems; Physics; Precision engineering, watch making; Speed variators, torque converters. Hydraulic drives and controls, pneumatic drives and controls, fluids and components, hydraulic motors, pneumatic motors; Valves; Voltage
• ISSN: 0960-1317; 1361-6439
• DOI: 10.1088/0960-1317/22/2/025019

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 µm parylene layer with a 58 µm 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.