Silicone-enhanced polyvinyl alcohol hydrogels for high performance wearable strain sensors

Flexible wearable strain sensors based on hydrogels have become a research hotspot in recent years due to their advanced application in many fields. Currently, most hydrogel-based strain sensors exhibit poor mechanical properties and low sensitivity. In this work, a conductive hydrogel as a wearable strain sensor was developed based on dual crosslinked polyvinyl alcohol (PVA) networks. The PVA was the main skeleton of the hydrogel and the water-soluble amino-polysiloxane (APSi) introduced into this hydrogel was the secondary network. The APSi and PVA were locked together by phytic acid (PA), which improved the microstructure and enhanced the mechanical properties of the hydrogel. This was mainly reflected in the higher tensile strength (1.27 MPa), elongation at break (425.5%), electrical conductivity (0.975 S/m), linearity (R2 = 0.999) and tensile strain sensitivity (gauge factor (GF) of 2.29). The tensile strength (0.166–1.270 MPa) and elongation (170.2–425.5%) of the hydrogel can be regulated continuously by adjusting the amount of APSi. These silicone-enhanced PVA hydrogels have good biocompatibility and hence can be used as wearable strain sensors.