关键词: 柔性压力传感器, 表面微结构, 灵敏度, 热塑性聚氨酯, 注射压缩成型

Abstract: The flexible thermoplastic polyurethane sheets with the single- and dual-level microcolumn arrays were rapidly prepared by using injection-compression molding with two different template design schemes. The microstructured flexible sensing substrates were obtained after cutting the sheets and spraying gold layer on them. The flexible pressure sensors were prepared by assembling the sensing substrates with the single-/dual-level microcolumns and the flat sensing substrate face-to-face， which were denoted as sensor 1 and sensor 2， respectively. The simulated results show that higher contact stress appeares around the edges on the top surfaces of the microcolumns under pressure. The longitudinal sections of the single- and dual-level microcolumns under pressure exhibit  “bowl” and “bud” geometries， respectively. The dual-level microcolumn can be deformed under lower pressure， and the contact deformation and contact area with the flat sensing substrate under pressure are larger. Therefore， compared to sensor 1， sensor 2 exhibits a higher sensitivity（0.53 kPa-1,0~1 kPa）， shorter response time/relaxation time（100 ms/80 ms）， lower detection limit（about 58 Pa）. Sensor 2 has a wide detection range（0.058～600 kPa）and maintaines a relatively stable piezoresistive response in 4000 cycles of compression/release tests（under a peak pressure of about 500 kPa）， which is ascribed to higher pressure resistance of the microcolumn. Sensor 2 may accurately detect human pulse, vocalisation and movement, demonstrating its potential for smart wearable applications. 

Key words: flexible pressure sensor, surface microstructure, sensitivity, thermoplastic polyurethane, injection-compression molding