CAREER: High Force, High Speed Electro-Thermal Micro-Actuators: Design, Fabrications, and Applications

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The absence of suitable actuators limits the development of silicon-based microsystems. For in-plane actuation, the best contenders are electrostatic and thermal actuators, but the former require high drive voltages, and both deliver forces in the range of only about 1-10 uN. This proposal addresses a new class of electrothermal microactuators that promises 100X increase force and 10X reduction in drive voltage. They leverage deformations caused by localized thermal stresses to efficiently produce large forces without compromising displacement.The devices will be designed by two complementary approaches, and further refined by numerical analysis in conjunction with optimal design of experiments. Designs that offer rectilinear, circular and customized loci of motion will be developed and evaluated for performance criteria such as output force and displacement, input power, drive voltage, response speed, device lifetime, trajectory errors, mechanical vibration, etc. Time-sequenced engines such as inchworms, which offer high displacement and force with negligible standby power, will also be developed. Designs will be fabricated in multiple technologies to permit comparative evaluations of performance and degradation mechanisms. Maskless process variations are proposed for standard technologies for selective confinement of heat and current flux, which minimize power consumption and response time.Preliminary results indicate that static displacements 100 microns and peak forces 1 mN are feasible with standard technologies. Several applications are proposed, with complementary demands on various performance aspects: a positioner for scanning probe microscopy; a positioner for optical elements in a micro-optomechanical system; and a sliding shunt for high-frequency telecommunication systems. In the long term these actuators will also be used to develop haptic interfaces, e.g. for simulating microsurgery.One educational objective is to increase the participation of under-represented groups in the MEMS research community using early recruitment programs and interaction with student groups. Another is to facilitate interdisciplinary education using practical engineering projects that force the convergence of multiple specialties to fill the pedagogical gaps between relevant departments. These efforts will be reinforced by interactions with industry.