Stylus type MEMS texture sensor covered with corrugated diaphragm

In this paper, a stylus type MEMS texture sensor covered with a corrugated palylene diaphragm, which prevent debris from jamming into the sensor without significant degradation of sensitivity and bandwidth, was reported. A new fabrication process using a lost-foil method to make the corrugated diaphragm on a 3-axis piezoresistive force sensor at wafer level has been developed. The texture sensor could detect the surface microstructure as small as about 10 μm in lateral direction and 1.7 μm in vertical direction. The output signals from the sensor were repeatable, and the Z-axis signal was almost the same regardless of the moving direction, indicating that the hysteresis was small enough. In addiiton, the bandwidth as wide as 1.1 kHz and 500 Hz in lateral and vertical directions, respectively, were confirmed. The surface roughness and friction coefficient of various materials were successfully detected by the fabricated texture sensor.