Multi-stimuli-responsive conductive and luminescent hydrogels for wearable sensors and information encryption transmission

Abstract

Flexible electronic sensors with optical functions have promising applications in wearable sensing, information storage, encryption and transmission, but realizing multifunctional applications in a single system is still challenging. Herein, the conductive and luminescent hydrogel in a single system was fabricated by non-covalent crosslinked poly(vinyl alcohol) (PVA) network and covalent crosslinked acrylamide (AAm) and [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA) network, as well as doping Eu(PDA)3 and glycerol (GL). The acquired PVA0.9/P(AAm-co-SBMA0.5)/Eu(PDA)3/GL (P0.9P0.5EG) hydrogel possesses excellent mechanical properties, adhesion, self-healing capability, water retention ability, anti-freezing property, conductivity, self-powered property, and luminescent properties. Importantly, the hydrogel as a flexible sensor has excellent tensile strain sensitivity (GF = 17.8), pressure sensitivity (S = 1.191 kPa−1), quick response, and stable electrical signals output, which can be used for monitoring multiple movements as well as for information transmission with the help of Morse code. Moreover, the unique luminescent properties and multi-stimuli-responsive behavior also make the hydrogel monitor strain variations via detecting the luminescence signal changes. Notably, the particular process of information encryption transmission was further achieved by converting the luminescence signals to electrical signals. This work provides an alternative strategy for designing and preparing hydrogel sensors for multifunctional applications.