Development of polyimide-based flexible tactile sensing module integrated with strain gauges & flexible flat cable

A flexible tactile sensing module with NiCr strain gauges as sensing elements was fabricated by polymer MEMS technology using polyimide materials where the one was the photo-definable polyimide precursor and the other was nonphoto-definable. The unit sensor cell size of 32×32 tactile sensor array was 1mm × 1mm cell and its overall size was 5.5cm × 6.5cm. Especially, both the tactile sensor arrays and the pluggable terminals as flexible flat cable were fabricated on the same polymer substrate easily to be connected the sensor array with a PCB board. The fabricated tactile sensing module was measured continuously in the normal force range of 0∼1N with tactile sensor evaluation system. The value of resistance was relatively linear with normal force in the overall range of 0∼1N. However, the variation of resistance was decreased by more than 0.6N. The variation rate of resistance was 2.0%/N in the range of 0∼0.6N and 1.5%/N in the range of 0.6∼1N. Image display was identified corresponding by distribution of applied force. The flexibility of the sensing module was adequate to be placed on any curved surface as a cylinder.