A Flexible and Wearable Visual Pressure Sensing System Based on Piezoresistive Sensors and Alternating Current Electroluminescence Devices

Flexible pressure sensor, as an important research branch of electronic skin (e-skin), has attracted much attention and has been widely developed in recent years. However, pressure sensors normally transfer the pressure signals into electrical signals for sensing, and that requires the assistance of signal processing and readout circuits. Here, an alternating current electroluminescence (ACEL) device, a piezoresistive sensor, and an AC driver in series, forming a visual pressure sensing system (VPSS) is connected. The VPSS, as a stand-alone sensing system without readout circuit, can directly convert pressure signals into luminous intensity, which can be observed directly with the naked eyes. In order to obtain flexible and wearable functions, the integrated VPSSs are further designed and manufactured. The integrated VPSS with single sensing unit can be attached on human finger and foot for sensing human movements, such as finger bending and walking. The integrated VPSS with 2x2 sensing units can be used for sensing pressure distribution, such as sensing the pressure distribution inside the robotic gripper. The integrated VPSSs can be easily installed as stand-alone sensing modules and can be extended to more application fields, providing a unique idea for flexible pressure sensing. In this paper, a visual sensing system (VPSS) with separate components is first developed by combining alternating current electroluminescence devices and pressure sensors. Moreover, an integrated VPSS with single sensing unit and an integrated VPSS with 2x2 sensing units are further fabricated and can be used to sense human movements and pressure distribution.image