Integrated pressure and flow sensor in silicon-based ultrasonic surgical actuator

We report on a transducer that not only cuts tissue ultrasonically but also senses pressure and liquid flow rate during cutting. Horn-shaped silicon needles with integrated piezoresistive pressure sensors were fabricated using bulk micromachining technology. The needles were driven ultrasonically by bonded PZT-4 plates. The device can be driven at its /spl lambda//2 longitudinal resonance to cut and sense pressure, while cut tissue is aspirated through the needle by an external pump.