Pengyang Li,Haowen Zheng,Xu Zhao,Renjie Ding,Fuhua Xue,Jinhua Xiong,Zhong Chen,Qingyu Peng,Xiaodong He
Pressure sensors still face a great challenge to combine wide pressure range and high sensitivity into a sensor. Herein, we designed a tension–compression conversion structure and introduced a stiffness gradient design strategy to fabricate pressure sensors. This tension–compression conversion mechanism can convert the sensing performance of two–dimensional (2D) stretchable materials into the compressive sensing performance of devices, thus providing rich designability for sensors. The stacking of multilayer sawtooth structures allows the sensors to perceive pressure with high sensitivity (1.4 N −1 or 0.2 kPa −1 ) and provide linear sensing over a very wide pressure range (0.005–45.6 N or 0.035–316.7 kPa). Moreover, due to the open structure of the device, the sensor has the ability to work stably in underwater environments. This method of designing pressure sensing devices with two–dimensional stretchable strain sensors as sensing units will provide new ideas for the design of future sensors.
Recently, wearable piezoresistive tactile sensors have attracted considerable attention owing to their potential applications, ranging from electronic skin to human-machine interaction. However, it is still difficult to mitigate the trade-off between sensitivity and linearity. Inspired by the hierarchical and gradient structures in natural systems, a versatile resistive pressure-sensing platform with controllable stress transfer and contact areas was fabricated by designing gradient styrene-butadiene-styrene triblock copolymer (SBS) sponges followed by the deposition of silver nanoparticles (Ag NPs) and polypyrrole (PPy). The gradient porous structures accompanied by gradient stiffness and conductivity enabled the external force to be efficiently transferred and localized to the sensing areas. Furthermore, the structures enabled a controllable response to the external stress via the gradual activation of electron pathways . These synergistic effects enabled the bioinspired tactile sensors to possess excellent sensing performance, which is demonstrated by large sensing range (∼80%), large linear range (∼72%), high sensitivity (∼1.07), low hysteresis behavior (7.66%), fast response time (177 ms), and excellent durability (more than 1100 cycles). Important applications of tactile sensors, including wrist-pulse-signal detection, speech recognition, finger bending, and tactile interfaces, have been successfully demonstrated. This conceptually simple but powerful approach can be applied to other nanomaterial systems to develop next-generation electronics.
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