Unique MEMS characterization solutions enabled by laser Doppler vibrometer measurements

Micro-Electro-Mechanical Systems (MEEMS) devices present many difficult characterization challenges. In an environment where diniensions are measured in microns and mechanical resonant frequencies are measured in kilohertz, conventional measurement and characterization techniques cannot be used. Laser Doppler Vibrometer (LDV) technology offers many unique advantages for MEEMS characterization and troubleshooting. One of the key problems in characterizing and troubleshooting MEEMS devices is the separation of electrical and mechanical effects. By definition, MEEMS devices have integrated electrical and mechanical components to form electro-mechanical systems. When characterizing and troubleshooting these devices it is often difficult to determine whether an observed behavior is purely mechanical, purely electrical, or inherently electro-mechanical. Because LDV measurements are electrically inert and do not introduce mechanical artifacts, they are ideally suited for this application. Applied MEMS and Polytec PI have successfully developed LDV based measurement techniques that allow detailed characterization and rapid troubleshooting of MEEMS devices. Three real-world examples of MEMS characterization using a LDV are presented including, an optical micro-mirror, a robust low-noise accelerometer and a hermetic ceramic sensor package.