Anti-freezing and moisturizing PAA/PEDOT: PSS ionogels with multiple stimulus responses for flexible wearable electronics

Abstract

Hydrogel is a promising material for wearable electronics due to its good mechanical properties, electrical conductivity and body adaptability. However, subzero freezing and water loss under high temperature or prolonged placement are great challenges for hydrogels. Here, polyacrylic acid / poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PAA/PEDOT: PSS) ionogels were designed by entangling PAA and PEDOT: PSS chains with each other in a binary solvent system of water and ionic liquid (IL) and chemical cross-linking by N, N’-methylene bisacrylamide (MBA). It has excellent mechanical properties (8.3 kPa, > 500 %), skin-adapted Young's modulus (<10 kPa), high conductivity (8.06 S·m−1), and strong adhesion (13.3 kPa). Ionogel has a sensitive response as a sensor (GF = 2.08, 0–200 %; GF = 3.64, 200–400 %; GF = 4.58, 400–510 %). Especially, the freeze-resistance and long-term moisturizing properties make ionogels exhibit long-lasting and robust utility. As a scalable application platform, we demonstrate the potential applications of this novel ionogel as a body-conformable electronic product in a series of conceptual demonstrations, including full range of human motion response, human–machine interaction (HMI), temperature signal detection and TENG device assembly.