Research/Self-Assembled Vertical Comb-Drive Actuator

Self-assembled vertical comb-drive actuator†

MEMS researchers usually try to avoid the "process stiction" to have better processing yield of their MEMS devices. Small pieces of MEMS structures tend to suffer from the surface tension force of the rinsing liquid when it is about to dry up. It happens whenever the suspended structures are designed to be compliant to the surface tension force. We discovered that the surface tension force could be used as a useful tool for the self-assembling of MEMS devices.

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Initial offset of vertical comb drive mechanism by using stiction pads†

The SEM picture (top) is a MEMS scanner with the vertical comb drive actuators. Vertical comb drive actuators need an initial offset between the fixed and movable combs. We designed a stictin pad (a mesh structure) to be brought into contact with the substrate by the surface tension force of water, and used the motion to twist the torsion bar of the mirror to give the initial offset angle. The technique is used to develop the MEMS scanner for fiber optic endsocpe.

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Reference†

K. Isamoto, T. Makino, A. Morosawa, C. Chong, H. Fujita, and H. Toshiyoshi, "Self-Assembly Technique for MEMS Vertical Comb Electrostatic Actuators," IEICE Electronics Express Vol. 2 (2005) , No. 9, pp.311-315.
See also Research/Fiber Optic Endoscope with an Optically Modulated Micro Mirror.

HT 2006-05-07