Neuron-inspired multifunctional conductive hydrogels for flexible wearable sensors

Abstract

Conductive hydrogel-based flexible wearable sensor is considered as one of the best candidates for next-generation flexible wearable devices due to their flexibility, stretchability, and biocompatibility. However, its low sensitivity and single sensory function had limited its applications in emerging flexible wearable devices. Inspired by human neurons, the ultralong silver nanowires were combined with modified carbon black nanoparticles, and the composite conductive material (AgNWs/CB–OH) was utilized in combination with poly(vinyl alcohol)/tannic acid/poly(acrylamide) (PVA/TA/PAM) composite hydrogel to improve the conductivity of the composite conductive hydrogel and the sensitivity of the conductive hydrogel-based flexible wearable sensor via imitating the structure of neurons. Benefitting from the neuron-inspired structure of the composite conductive hydrogel, when a bit of composite conductive materials was added into the hydrogel (∼2.65 wt%), the conductivity of the composite conductive hydrogel was enhanced obviously, and the obtained composite conductive hydrogel-based flexible wearable sensor possessed high sensitivity (GF_max = 68.64, S_max = 0.229 kPa⁻¹), flexibility, stability (∼300 cycles), remoldability, and strain/pressure sensitivity. It could sensitively and stably detect human activity (e.g., finger bending, wrist bending, elbow bending, knee bending, mouth opening, making a fist, talking, walking, and jumping), demonstrating that the composite conductive hydrogel-based flexible wearable sensor is an ideal material for applications of full-range human bodily motion detection.