Silver-Hydrogel/PDMS film with high mechanical strength for anti-interference strain sensor

Hydrogels have recently emerged as promising candidates for wearable strain sensors. However, their poor mechanical stability and fragility limited their applications in many fields. Inspired by the skins, we developed a double-layer structured silver-Hydrogel/PDMS composite film (Ag-Hydrogel/PDMS) by chemically bonding the PDMS with a conductive Ag-Hydrogel layer. After assembled with the zinc, air electrodes and a fixed resistor, a self-powered Ag-Hydrogel/PDMS strain sensor was obtained. The mechanical properties of the Ag-Hydrogel/PDMS strain sensor was significantly enhanced due to the chemically bonded PDMS film. Compared to PDMS and Ag-Hydrogel alone, the tensile stress of Ag-Hydrogel/PDMS composite film increased by 3.4 and 58.1 times, respectively. The prepared Ag-Hydrogel/PDMS composite film could easily lift a 1050 g item without obviously interfacial failure. And it could output different voltage signals upon various finger motions without any external power supplies. Interestingly, the inert nature of PDMS also greatly improved the anti-interference property of the Ag-Hydrogel/PDMS strain sensor, as it protected the Ag-Hydrogel from the complicated environments. Moreover, excellent antibacterial activity of the Ag-Hydrogel/PDMS strain sensor against both of the E. coli and S. aureus bacteria was observed, which could be ascribed to the distribution of Ag nanocubes in the hydrogel matrix. The hydrophobic property of the PDMS layer further entitled the Ag-Hydrogel/PDMS strain sensor with a good bacterial anti-adhesion property. These characteristics guarantee the self-powered Ag-Hydrogel/PDMS strain sensor with potential application as wearable and portable electronic devices in complicated environments.