A novel bulk-micromachined electrostatic microvalve with a curved-compliant structure applicable for a pneumatic tactile display

Recent success of microelectromechanical systems (MEMS) in projection displ ays have raised similar expectation for an efficient, low power, affordable , full-page and pneumatic tactile display. Such design has not been achieve d by the conventional technology but could bring significant improvement to current refreshable Braille displays, This paper demonstrates a novel bulk -micromachined electrostatic microvalve suitable for a pneumatic tactile di splay, The microvalve, a silicon perforated diaphragm juxtaposed to a silic on inlet orifice, requires relatively low closing voltage against a large s upply differential pressure and flow rate, i.e., 72.9 V-rms for 19.3 kPa an d 86 mL/min. Such an attractive characteristic is due to its unique curved- compliant structure that has, unlike other electrostatic microvalves, no to lerance for any initial air gap between its electrodes, As a design tool, a mechanical model of the microvalve is introduced based on the lubrication theory and large plate deflection theory. The model is established on a ste ady-state coupled field problem of a fluid-solid mechanics, Reynolds and vo n-Karman equations were simultaneously solved for the microvalve geometry b y finite difference approximation and double Fourier series expansion, The results of the model and experiments are compared and found to be in good a greement with a relative error less than 10%.