Underwater,\nMultifunctional Superhydrophobic Sensor\nfor Human Motion Detection

Abstract

Superhydrophobic\nconductive materials have received a great amount\nof interest due to their wide applications in oil–water separation,\nelectrically driven smart surface, electromagnetic shielding, and\nbody motion detection. Herein, a highly conductive superhydrophobic\ncotton cloth is prepared by a facile method. A layer of polydopamine/reduced\ngraphene oxide (PDA/rGO) was first coated on the cotton fabric, and\nthen copper nanoparticles were in situ grown on the prepared surface.\nAfter further modification with stearic acid (STA), the wettability\nof the cotton surface changed from superhydrophilic to superhydrophobic\n(water contact angle (WCA) = 153°). The electrical conductivity\nof the PDA/rGO/Cu/STA cotton is as high as 6769 S·m^–1, while the stearic acid effectively protects Cu NPs from oxidation.\nAs a result, the superhydrophobic PDA/rGO/Cu/STA cotton has shown\nexcellent electrical stability and can be used in detecting human\nmotions in both ambient and underwater conditions. The sensor can\nrecognize human motion from air into water and other underwater activities\n(e.g., underwater bending, stretching, and ultrasound). This multifunctional\ncotton device can be used as an ideal sensor for underwater intelligent\ndevices and provides a basis for further research.