Synergy\nof Porous Structure and Microstructure in\nPiezoresistive Material for High-Performance and Flexible Pressure\nSensors

Abstract

A porous\nand microstructure piezoresistive material composed of\npolydimethylsiloxane (PDMS) and multiwalled carbon nanotubes (MWCNTs)\nwas designed and prepared for a flexible and highly sensitive pressure\nsensor over a wide detection range. The microstructure was patterned\non the surface of the partially cured PDMS/MWCNTs/NaCl mixture by\nimprinting a nonwoven fabric. After curing and dissolving the NaCl\npowders, the porous and surface microstructure PDMS/MWCNT film was\nobtained. Two PDMS/MWCNT films were stacked together and sandwiched\nbetween two copper foil electrodes, in which the two microstructure\nsurfaces were in contact with the electrodes. Due to the synergistic\neffects of the combination of the porous structure and surface microstructure,\nthe flexible sensor had highly sensitive response over a wide pressure\nrange from 1 Pa to 100 kPa. Under the small pressure, the high sensitivity\nwas achieved by the change in contact areas between the electrodes\nand the surface microstructures; at high pressure up to 100 kPa, the\nsensor retained its high sensitivity because of the porous structure\nof the piezoresistive PDMS/MWCNT material. Additionally, the sensor\nhad fast response speed and good durability. The piezoresistive pressure\nsensors based on the porous and microstructure PDMS/MWCNTs were demonstrated\nin detection of sound, monitoring of human activities, and array mapping\nof the spatial pressure distribution.