Estimation of squeeze film damping in artificial hair-sensor towards the detection-limit of crickets’ hairs

Abstract

The filliform hairs of crickets are among the most sensitive flow sensing elements in nature. The high sensitivity of these hairs enables crickets in perceiving tiny air-movements which are only just distinguishable from noise. This forms our source of inspiration to design highly-sensitive array system made of artificial hair sensors for flow pattern observation i.e. flow camera. The realization of such high-sensitive hair sensor requires designs with low thermo-mechanical noise to match the detection-limit of crickets’ hairs. Here we investigate the damping factor in our artificial hair-sensor using different methods, as it is the source of the thermo-mechanical noise in MEMS structures. The theoretical analysis was verified with measurements in different conditions to estimate the damping factor. The results show that the damping factor of the artificial hair sensor as estimated in air is in the range of 10−12 N m/rad s−1, which translates into a 93 μm/s threshold airflow velocity.