Electrostatic Micro-Hydraulic Hair Sensors and Actuators

A novel optimally designed electrostatic micro-hydraulic (EMH) structure is introduced to significantly improve performance of many MEMS devices for sensing and actuation. The EMH system in conjunction with application-specific appendages can realize high performance sensors and actuators. For instance, biomimetic hair-like structures can provide external airflow sensing with high accuracy and high resolution. Hairs with small footprints enable array fabrication to provide redundancy, fault tolerance and directional sensitivity. Additionally, the high accuracy of the conventional sensors is achieved at the expense of full-scale range. Using the EMH structure a new type of low-power, accurate and robust flow sensor has been fabricated and tested in which a hair-like appendage is used to translate flow into hydraulic pressure. This pressure is sensed with an integrated capacitor within the EMH system by which the sensitivity is amplified. The air flow sensor exhibited about 78.9 dB of range to minimum detection ratio, which is the highest range over resolution ratio to best of our knowledge.
The EMH structure can also be used as a platform to realize many cross-disciplinary high performance devices. This platform has been used to make tactile sensors resembling human skin that are needed in humanoid robotics. Additionally, these structures have been tested in actuation mode to possibly form micro-valves for micro-fluidic circuitry and have the ability to provide hexa-pedal locomotion pattern for micro-scale robotic applications.