In recent years, with the rapid development of prosthesis, [1,2] health monitoring, [3][4][5][6][7] and robot, [8][9][10] electronic skin has drawn huge research enthusiasm. Tactile sensation is one of the most significant functions of electronic skin, which mainly relies on pressure sensor to realize. [11][12][13][14][15] Among the different kinds of pressure sensors, piezoresistive pressure sensor demonstrates great application potential because of its fast response speed, simple structure, economical fabrication process and great stability. [16][17][18][19][20] Improvement of sensitivity of pressure sensors is critical for the high precision and ultrasensitive pressure detection, [21][22][23][24][25] which is however a challenging task because the key effect of device configuration on the sensitivity is always neglected.Until now, the commonly used strategy to improve sensitivity focuses on the development of different kinds of microstructure of active materials, but this strategy is still not effective enough to achieve ultrahigh sensitivity. [26][27][28] For example, Fang et al. replicated the lotus leaf surface onto the polydimethylsiloxane (PDMS) substrate to produce a structured layer and then sprayed graphene films as active electrodes, [29] which yields a sensitivity of 1.2 kPa −1 . Jong-jin Park et al. reported a sensor with sensitivity of 10.32 kPa −1 by introducing a pyramidical electrode consisting of a conductive polymer (PEDOT:PSS) and an aqueous polyurethane dispersion (PUD) elastomer blend. [30] Bao et al. prepared a new piezoresistive sensor with sensitivity up to 41.9 kPa −1 by preparing interconnected polypyrrole (PPY) hollow sphere structure through a multiphase synthesis technique. [31] These researches have significantly advanced the development of piezoresistive sensors, but still could not achieve ultrahigh sensitivity to meet the requirement of high precision and ultrasensitive detection. This is because the surface microstructure of active materials is not the only key factor for the improvement of sensitivity.To overcome the current obstacle and get ultrathigh sensitivity, it would be necessary to understand the basic working principle of piezoresistive pressure sensor, and further get the feasible solution. The basic electrical characteristics of piezoresistive sensor is similar, and the total resistance (R total ) of the device consists of two parts: the body resistance (R b ) Improvement of sensitivity of electrical piezoresistive sensors is critical for high-precision and ultrasensitive detection, which mainly depends on the modulation ability of total resistance of sensor under applied pressure. However, in most of the reported sensor devices, the contact resistance and body resistance (the key parts of total resistance of sensor) generally cannot be modulated simultaneously, which results in the limited sensitivity. In this work, an ultrahighly sensitive piezoresistive pressure sensor with an exquisitely designed structure is demonstrated, providing an uncomparable advantage of ...
In article number 1901084, Jie Li, Hongzhen Lin, Liqiang Li, and co‐workers introduce an ultrahighly sensitive pressure sensor based on the unique synergistic resistance modulation effect, which shows great potential in detecting subtle pressure signals induced by ringtone, pulse and breath. More importantly, it offers a new strategy for designing high‐performance pressure sensors.
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