A liquid-filled microrelay with a moving mercury microdrop

A micromechanical relay that switches by moving a mercury microdrop is introduced. While microrelays have been introduced to MEMS on several occasions, all are based on solid-solid contacts, making them subject to contact wear, signal bounce, and general loss of performance with use. The goal of our device is to use mercury to eliminate the common problems of solid-contact switches. Descriptions of the design and fabrication of a micromechanical mercury-contact relay, including the technique for formation of microscale mercury droplets, are presented. The deionized (DI) water-filled microrelay has a mercury droplet, 5-25 /spl mu/m in diameter, placed near a disconnected set of electrodes in a V-groove throat. The throat connects two reservoirs containing suspended heaters. By turning on one heater, we grow a vapor bubble in one reservoir and induce a momentary water flow along the throat, forcing the mercury droplet to move and create the signal conduction path. Heating of the second reservoir can drive the mercury drop back to its original position. A microgasketing technique along with UV-curing epoxy sealing method is introduced to seal a chip containing many microdevices, each filled with liquid, at room temperature. Initial test results of the relay are also provided.