Title :
A micro strain gauge with mechanical amplifier
Author :
Lin, Liwei ; Pisano, Albert P. ; Howe, Roger T.
Author_Institution :
Dept. of Mech. Eng., Michigan Univ., Ann Arbor, MI, USA
fDate :
12/1/1997 12:00:00 AM
Abstract :
A passive micro strain gauge with a mechanical amplifier has been designed, analyzed, and tested. The mechanical amplifier provides a high gain such that residual strain in thin films can be directly measured under an optical microscope. This strain gauge can be in situ fabricated with active micro sensors or actuators for monitoring residual strain effects, and both tensile and compressive residual strains can be measured via the strain gauge. It is shown that a very fine resolution of 0.001% strain readouts can be achieved for a micro strain gauge with a 500 μm-long indicator beam. Beam theories have been used to analyze the strain gauge with a mechanical amplifier, and the results were verified by a finite-element analysis. Experimental measurements of both polysilicon and silicon-riched silicon-nitride thin films fabricated by surface micromachining processes are presented
Keywords :
finite element analysis; micromachining; microsensors; strain gauges; strain measurement; 500 micron; FEM; Si; Si3N4; compressive residual strain; finite-element analysis; indicator beam; mechanical amplifier; microsensor; optical microscopy; passive micro strain gauge; polysilicon thin films; silicon nitride thin films; surface micromachining processes; tensile residual strain; Capacitive sensors; Gain measurement; Mechanical variables measurement; Optical amplifiers; Optical films; Optical microscopy; Semiconductor optical amplifiers; Strain measurement; Tensile strain; Testing;
Journal_Title :
Microelectromechanical Systems, Journal of
