Enhanced Sensing and Electromagnetic Interference Shielding Performance of Hydrogels by the Incorporation of Ionic Liquids

Conductive polymer hydrogel-based sensors with high-performance electromagnetic interference shielding effectiveness (EMI SE) have attracted much attention. In this field, the tremendous challenge is achieving an even dispersion of the conductive fillers in order to enhance their sensitivity and SE. Herein, ionic liquids (ILs), the ionic conductors, are chosen to optimize the morphology of polyaniline (PANI) on graphene oxide (GO) and improve the dispersion of PANI@GO (PGO) in sodium alginate/polyacrylamide (SA/PAM) hydrogels. Because of the presence of an electron–ion conductive network, the resulting SA/PAM/IL@PGO hydrogels exhibit a conductivity of 0.13 S/m, which is 21.7 times higher than that of SA/PAM/PGO hydrogels. This outstanding electron–ion conductivity endows the SA/PAM/IL@PGO hydrogels with an EMI SE of 53.6 dB and a low reflection coefficient, indicating excellent green shielding ability. More importantly, the gauge factor of resulting SA/PAM/IL@PGO hydrogels reaches 3.03, suggesting high sensitivity, so they can be used as strain sensors to monitor vigorous bodily movements. This work provides a strategy for fabricating hydrogels as high-sensitivity sensors with a high-performance shielding capability.