Superhydrophobic and conductive polydimethylsiloxane/titanium dioxide@reduced graphene oxide coated cotton fabric for human motion detection

Superhydrophobic materials with special functions of electrical conductivity, magnetism, photothermal conversion and others have been paid considerable attention in the emerging fields including wearable electronics, long-distance manipulation and seawater desalination. Herein, we report a facile approach to fabricate superhydrophobic and conductive cotton fabric (CF) for piezoresistive pressure sensor. It was based on the utilization of the reduced graphene oxide (rGO) layer on CF to form conductive pathways. Meanwhile, the in-situ generated hybrid of polydimethylsiloxane (PDMS)/titanium dioxide (TiO₂) on rGO layer through the hydrolysis-condensation and cross-linking reactions between dihydroxyl-terminated PDMS and tetrabutyl titanate played the role of constructing rough structure and decreasing surface energy. The fabricated PDMS/TiO₂@rGO coated CF exhibited a high water contact angle of 159.3° and possessed outstanding self-cleaning ability. Interestingly, owing to the existence of TiO₂, the CF also had the capability to degrade organic contaminations and the degradation rate reached 96.4% after being exposed under UV light for 90 min. In addition, the PDMS/TiO₂@rGO coated CF with a low electrical surface resistance of 0.76 kΩ cm⁻¹ was utilized to design and prepare a multilayer piezoresistive pressure sensor by means of the large number of air gaps between the fibers and the increase of contact points under external pressure. The sensor showed high sensitivity, fast response and good repeatability, and was successfully applied for detecting different human behaviors including pulse, voice recognition, and body motion. Our findings conceivably stand out as a new methodology to fabricate functional superhydrophobic materials and surfaces for practical applications in the fields of electronic skin, human healthcare, interactive wearable device and smart robotics.