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19 January 2007 Testing reliability of MEMS materials in liquids
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MEMS are increasingly being considered for applications that involve immersion in liquids. However, there are very little reliability data for MEMS structures in liquids environments. In this study, an apparatus was developed which enables the investigation of fatigue failure of MEMS in liquids. MEMS cantilever beams were mounted on a PZT piezoelectric actuator and immersed in a liquid. A laser is reflected off the tip of the vibrating cantilever and onto a position-sensing photo-diode device (PSD) to obtain position data. From this data resonance frequency can be extracted for long-term monitoring. Cantilevers are resonated for at least 108 cycles. This apparatus allows for the testing of many combinations of materials and environments. For this study, the fatigue performance in liquid of silicon nitride cantilever beams was evaluated and compared to single crystal silicon cantilever beams. Tests were conducted in deionized water and a saline solution. Silicon nitride exhibited no long-term degradation of resonance frequency within measurement limits in air, DI water, and saline environments. Silicon exhibited a steady decrease in resonance. Results showed that this method could be extended to conduct reliability studies on other MEMS materials.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Thomas P. Kuehn, S. Mubassar Ali, Susan C. Mantell, and Ellen K. Longmire "Testing reliability of MEMS materials in liquids", Proc. SPIE 6463, Reliability, Packaging, Testing, and Characterization of MEMS/MOEMS VI, 64630L (19 January 2007);

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