Highly sensitive active-powering pressure sensor enabled by integration of double-rough surface hydrogel and flexible batteries

A conductive, elastic, and biocompatible hybrid network hydrogel was prepared by cross-linking of locust bean gum, polyvinyl alcohol, and carbon nanotubes, yielding a rough top surface and smooth bottom surface. The merging of the two pieces of hydrogel flat face to flat face forms a highly elastic hydrogel with double-rough surfaces. A piezoresistive sensor assembled with the double-rough surface hydrogel sandwiched between two carbon cloth electrodes exhibits a high sensitivity (20.5 kPa-1, 0-1kPa), a broad detection range (0.1–100 kPa) and a reliable response for 1000 cycles. The rough contact area between the hydrogels and the carbon cloth is found critical in achieving ultra-high sensitivities in the low-pressure range. Moreover, further monolithic integration of the sensor with a flexible solid-state zinc ion battery ensures the self-powering of the sensor for various human motions detection applications.