Improving Performance of Microstructured Flexible Pressure Sensor under Low Mechanical Stimulation by Micro-papillae
A novel approach is proposed to rapidly prepare dual-level microstructured flexible pressure sensors with micro-papillae,which are applied in weak physiological signals detection.The flexible thermoplastic polyurethane sheets with the dual-level and single-level microdomes array and the flat surface are rapidly prepared by using compression molding.Then the gold-sprayed microstructured sheet and the graphite-coated flat sheet are assembled into flexible piezoresistive pressure sensors face-to-face.It is demonstrated that the dual-level microstructured pressure sensor(D-Sensor)with micro-papillae distributed on the surface of microdomes exhibits a higher sensitivity(0.061 kPa-1)and obviously higher linearity(with a linear correlation coefficient of upto 0.996)in linear low-pressure region(0～11 kPa)than the pressure sensor with the single-level microdomes array.This is attributed to the fact that the deformation of the dual-level microdomes under pressure obeys the Archard theory,and the area of the contact regions is increased largely with raising pressure.The D-Sensor has a short response time(100 ms)and maintains a stable piezoresistive response during 1000 cycles of cyclic compression/release tests(under 9 kPa pressure).The D-Sensor can accurately monitor some physiological signals corresponding to weakly mechanical stimulation,such as wrist pulse,pronunciation,and respiration.The results demonstrate that the dual-level microstructured sensors fabricated by the proposed rapid approach has high sensing performance and so can be applied in health detection field.
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