Low voltage micro-electro-mechanical systems (MEMS) for actuators and optical devices

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The small size and high performance of MEMS based devices has resulted in their wide usage in many scientific and industrial sectors, such as communication, medical, transportation, and consumer electronics. A foundation technology behind many MEMS are micro-actuators, with electrostatic, thermal, and Lorentz magnetic actuators widely used. Numerous challenges exist, however, when implementing actuators with large movement stroke and high force. Thermal actuators need higher power, and heat loads are an issue in many applications and multiply in array usage. Parallel plate electrostatic actuators offer the benefit of compact size, simple fabrication, and near-zero power requirement when holding fixed position, but require higher voltage to overcome the forces required in large stroke applications. This often necessitates external power supplies, eliminating the size reduction offered MEMS technology. Lorentz magnetic actuators offer low voltage operation, at the expense of size increase for larger magnets and conductors. There is need to develop low voltage and power micro-actuators, that offer large stroke and force, that can be powered by on-chip drive circuits. The long-term objective of this research is to contribute to the development, optimization, and application of MEMS and micro-actuator technologies. The proposed research will undertake the following investigations towards high stroke micro-actuators, that have low voltage and power requirements. Novel tri-electrode actuators will be investigated, that offer the combined benefits of reduced voltage, extended range before snap-down, and compact size. They are a new category of parallel plate electrostatic actuators, and their performance needs to be studied and optimized in consideration of their design, the fabrication materials used, and specific application. Fabrication methods will be developed and experimentally implemented, to explore their performance in narrow aspect devices and micro-switches, and controllable focus and large rotation angle mirrors. Low voltage and compact Lorentz actuator arrays will also be an investigation, and applied towards deformable mirrors. Large diameter flexible metal-polymer mirrors will be developed, and implemented with these two categories of actuators, with the goal to enable compact long stroke deformable and adaptive optics systems. Finally, flexible PCB substrates will be explored, with tri-electrode and Lorentz actuator arrays, for low cost deformable surfaces. The developed actuator technologies will offer advance to broad MEMS applications, such as long stroke high isolation switches and variable capacitors, variable focus mirrors, long stroke low cost adaptive optics (for microscopy, astronomy, optical communications), and adaptive RF components.