MICROMACHINED VALVE WITH HYDRAULICALLY ACTUATED MEMBRANE SUBSEQUENT TO A THERMOELECTRICALLY CONTROLLED BIMORPH CANTILEVER

We report on the design, fabrication and performance of a micromachined valve for hydraulic applications. The valve is composed of a stack of four silicon wafers and utilizes a new actuation principle, which to our knowledge is presented for the first time in this paper: a fluid jet formed at a nozzle is passing along a bimorph cantilever; electrical actuation of this cantilever causes a deflection of the fluid jet towards a volume below a bossed membrane, where its kinetic energy is partially retransformed into pressure energy; this pressure lifts the membrane, thus opening the outlet hole of the valve; i.e., the valve is open or closed corresponding to whether the bimorph cantilever is heated or not. The outer dimensions of the valve are 14.5 x 8.5 x 1.43 mm(3). It is designed for flow rates of about 75 ml/min at a system pressure level of about 6 bar. Efficient cooling of the cantilever by the fluid jet allows a maximum operating frequency as high as 1 kHz.