Publication

Hydrogels are promising materials for strain sensors due to their stretchability, flexibility, and biocompatibility properties. However, previously reported hydrogel based strain sensors have poor sensitivity, which is not enough to detect subtle human motions. In this study, we introduced a vinyl silica nanoparticles (VSNPs)/poly acrylamide (PAAm)/alginate hydrogel based strain sensor for the human motion detection. Vinyltriethoxysilane (VTES) was converted to VSNPs using a sol-gel process, which can serve as a cross-linker and stress buffer to dissipate energy [1]. Furthermore, alginate built an independent network which is able to disperse energy [2]. As a result, modified hydrogel structure originated from VSNPs and alginate provides improved sensitivity of the strain sensor. Figure (a) depicts fabrication sequences of the developed VSNPs/PAAm/alginate hydrogel of strain sensor. Figure (b) shows fabricated strain sensor. Similarly, figure (c) shows the relative resistance change of the hydrogel during stretching and releasing conditions. The fabricated VSNPs/PAAm/alginate hydrogel based strain sensor exhibited much larger relative resistance change and higher sensitivity compared to PAAm hydrogel based strain sensor, as shown in Figure (d) The strain sensitivity, i.e., gauge factor of the hydrogel under the strain of 100 % was calculated to 1.74, as shown in Figure (e).