| This thesis presents important results on fabrication, instrumentation, and testing on silicon-based ultrasonic actuators that can do work on tissue. As the main result, a feedback controlled silicon-based high-power ultrasonic horn actuator with integrated strain gauges is presented. The design of the energy concentrating horn is optimized by finite element method simulation to minimize the resonance quality factor from packaging, while enhancing the sensitivity of the strain gauge to measure the dynamic strain. The polysilicon piezoresistive strain gauges are used to measure static force applied to the tool and ultrasonic strain of the tool. The measured ultrasonic strain is used as an input to board-level phase-locked loop electronics for closed loop control of the resonator displacement. With this feedback control, the actuator is able to deliver ultrasonic energy effectively at different loading conditions by maintaining it at resonance.; An integrated polysilicon strain-gauge process is developed, using TMAH to etch silicon, making the process more CMOS compatible. The significant challenge of aluminum passivation in TMAH etch over extended etches was solved by not only understanding the etchant chemistry, but also the mechanisms of aluminum and polysilicon etching at the polysilicon-metal interface. A process enhancing a dual-doped TMAH passivation of aluminum during long-duration through-wafer silicon etching is demonstrated which provides guidelines on the aluminum sputtering conditions.; Thin film Silicon nitride thin films have been characterized for cutting at the microscale. Fabrication and strength analysis of SiN/metal composite blades is developed. A novel thin-film evaporator-compatible “rotisserie” was designed to coat metal on both sides of a wafer for SixN y blades without uneven residual stress.; Remotely actuated magnetic microactuator with integrated piezoresistive strain gauge for displacement feedback is demonstrated. The remote actuation scheme provides a possibility of high power magnetic actuation in microsurgical applications without the need for wiring to the actuator. A novel magnetic extrusion is developed to fabricate magnetic end-effecter. This process provides a simple, inexpensive, and quick method to make high aspect paramagnetic actuator column. The actuator has been tested under water, and was shown to generate water stream and strong agitation that can be used to disrupt tissue. |
