Abstract
This paper proposes a novel shear stress sensor based on the principle of Fabry-Perot interferometer and fabricated by polymer-MEMS technology. The surface roughness of the floating element, fabricated by UV lithography on SU-8 resist, is better than 7nm on 15∗15 μm 2 area and suitable for reflection mirrors. Silicon oil is filled into the sensor cavity as a refractive-index matching medium for signal enhancement as well as a buffer material for pressure resistance and vibration reduction. Filled with silicon oil, the sensor sensitivity can be improved as by 1.4 times and signal intensity is increased by 16.4dB, respectively. The minimum detectable displacement and shear stress have been characterized to be 10nm and 0.33Pa, respectively. Besides, signal spectrum shifts have been tested within 1nm, under static pressure from 1 to 6 atm, or acoustic vibration from 1 to 5 kHz, thanks to the incompressibility and damping effect of silicon oil.