A low-voltage, low-power microvalve that can be actuated either elecfrical!y using the inversepiezoelecbic effect or thermally using the pyroelectric effect is presented here. The valve consists of external lasermachined bulk piezoelectric unimorph actuators mechanically linked to surface micromachined nickel cap structures anchored on silicon nitride membrane tethers. A self-aligned mechanical linking process for the assembly of external bulk piezoelectric actuators to micromachined silicon structures enables motion from the piezoelectric unimorph to be coupled to tethers. Valve cap strokes as large as 4.8 pm were realized for an actuation voltage of 10 V consuming switching energy of 600 nJ. Linear control of fluid flow in the 0 -50 pYmin was accomplished with pulse width modulated 10 Vpp drive at frequencies as high as 1 W z .
In this paper we report our progress on the development of silicon-based surgical tools. We report on the integration of piezoresistive sensors in noise insensitive Wheatstone configuration, silicon nitride/platinum composite overhanging blades, fluid channels, and electrical packaging features to make the device highly multifunctional.Multiple polysilicon piezoresistors were integrated onto bulk micromachined ultrasonic transducers, that were characterized for measuring the ultrasonic strain and the force applied to the cutting tip. The use of thin film silicon nitride/metal composites for cutting swine retinas at the cellular level is demonstrated.
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