Design and fabrication of an electrochemically actuated microvalve

Abstract

A microfluidic valve based on electrochemical (ECM) actuation was designed, fabricated using UV-LIGA microfabrication technologies. The valve consists of an ECM actuator, polydimethylsiloxane (PDMS) membrane and a micro chamber. The flow channels and chamber are made of cured SU-8 polymer. The hydrogen gas bubbles were generated in the valve microchamber with Pt black electrodes (coated with platinum nanoparticles) and filled with 1 M of NaCl solution. The nano particles coated on the working electrode helps to boost the surface-to-volume ratio of the electrode for faster reversible electrolysis and faster valve operation. To test the functionality of the microvalve, a simple micropump based on ECM principle was also integrated in the system to deliver a microscopic volume of fluid through the valve. The experimental results have showed that an approximately 300 lm deflection of valve membrane was achieved by applying a bias voltage of -1.5 V across the electrodes. The pressure in the valve chamber was estimated to be about 200 KPa. Experimental results proved that the valve can be easily operated by controlling the electrical signals supplied to the ECM actuators.

Liquid‐Crystalline Elastomer Microvalve for Microfluidics

“…The most common active microvalves for flow control are based on mechanical actuators (e.g. pneumatic,5–10 thermopneumatic,11–15 thermomechanical,16–19 piezoelectric,20–25 electrostatic,26–31 electromagnetic,32–35 electrochemical,36, 37 or capillary‐force actuators)38 in order to control/stop the flow, contain the fluid, and isolate regions in the microfluidic device 39, 40…”

Microvalves and Micropumps for BioMEMS

“…The valves can be actuated mechanically [1][2][3][4], pneumatically [5][6][7][8][9][10][11][12][13], electrokinetically [14][15][16][17], by phase changes [10,11,[18][19][20][21][22], or by introduction of external force [23,24]. Using the method of actuation as the differentiating parameter, five major classes of active microvalves can be identified in the literature: electrokinetic, pneumatic, pinch, phase change, and burst.…”

Design Considerations for a Micromachined Proportional Control Valve

“…Recent examples are hydrogel [35], ionogel [36] or electrochemical actuators [37]. Similar to thermopneumatic actuators, they suffer from very long response times on the order of seconds to minutes, which is too slow for mass flow control.…”