Phytic acid assist for self-healing nanocomposite hydrogels and their application in flexible strain sensors

Nanocomposite hydrogels have been applied in the field of flexible sensors to monitor human body signals. In this manuscript, phytic acid (PA) was successfully adsorbed on the surface of graphene oxide@polydopamine (GO@PDA). The obtained graphene oxide@polydopamine-phytic acid (GO@PDA-PA) was further implanted to the poly acrylic acid (PAA) hydrogels as flexible strain sensors. Dopamine (DA) was self-polymerized on both two sides of GO by mussel-inspired chemistry to synthetize GO@PDA. PA was decorated on the surface of GO@PDA to obtain GO@PDA-PA nanocomposites with Pickering emulsion in oil-in-water (O/W) emulsion. The GO@PDA-PA hydrogels’ self-healing efficiency (98.6%) and mechanical strength (1.77 MPa) were both improved due to the presence of reversible interaction such as hydrogen bond and metal-ligand coordination. The wearable flexible sensors based on the prepared GO@PDA-PA hydrogels have high sensitivity (gauge factor (GF) = 3.3), stability, durability and high response ability. It can detect the sharp movement signals of human body and tiny movement signals such as breathing. The excellent performance of nanocomposite hydrogels is expected to promote the evolution of flexible sensors.