The limitation of many currently available actuators, and in particular smart material actuators, is their small stroke and power. In the formation of microelectromechanical (MEM) devices, a motive forcer or actuator is required. The previous used electrostatic comb actuators have generally consumed a large portion of the die on which the MEM device is formed. Further, the die size is constrained by available steppers used for the photolighographic processes. As a result, the size and complexity of MEM devices is presently constrained by the size of the actuator used. As such, there is a need in a MEM device for a mechanism that multiplies the range of displacement from a short-stroke actuator and provides an increased range of displacement that is sufficient for actuating a particular MEM device.
Researchers at the University of Michigan have developed a pivotless compliant structure for receiving an input displacement from a motor source and generating a multiplied displacement for provision to a load. This device can be used on a variety of scale sizes including MEM structures. The compliant structure, based on a combination of interconnected flexible beams and cross beams formed of one or more layers of polysilicon or silicon nitride, can provide a geometric advantage to stroke displacement provided by a short-stroke actuator. The compliant structure has less play than conventional displacement-multiplying devices based upon lever arms and pivoting joints, and is expected to be more reliable than such devices. An output displacement range can be greater than a multiplication factor of 5-60 than the first linear displacement range when that first range is 5 microns or less. An output displacement range can also be less than the first linear displacement range by about 1/5 to 1/60.
Applications and Advantages
- MEMS actuators
- Energy efficient, easy to manufacture, long lasting, and highly reliable
- Enables use of compact short-stroke electrostatic or thermal actuators to generate a suitable range of displacement in driving MEM devices