The sensor measures a broad range of pressure signals. (Credit: Terasaki Institute)

New skin-sensing wearables for pressure-sensing applications use a solutions-based method to coat copper nanowires with graphene oxide (GO); validation tests confirmed that this method imparted a uniform, strongly bonded GO layer onto the nanowires, which effectively protected them against corrosion without sacrificing their conductive properties. Furthermore, the method allowed for variation of GO coating thickness by adjusting the reaction time or the amount of GO added.

The team devised a method of molding an elastic polymeric substrate layer onto a sheet of sandpaper to imprint the sandpaper’s rough texture onto the substrate’s surface. The substrate was then treated chemically to enhance its bonding to the nanowires. Next, a suspension of the GO-coated copper nanowires was sprayed onto the substrate and thermally treated to chemically reduce, or lower the oxidation state, of the GO to strengthen the adhesion between the layers.

Mechanical experiments with the reduced GO-coated copper nanowires (CurGONW) PS were conducted, with various compression stress levels and rates tested. Because of the elasticity and fast response times of the sensor, it exhibited overall stable resistance measurements maintained over 1000 stress cycles.

The team has fabricated an effective piezoresistive pressure sensor using low-cost, simple, scalable, tunable, and modular methods. Due to the novel skin-inspired microstructure of its substrate layer, the sensor was able to measure a broad range of pressure signals with accuracy and high sensitivity.

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