Highly conductive and sensitive acrylamide-modified carboxymethyl cellulose/polyvinyl alcohol composite hydrogels for flexible sensors

Conductive hydrogels were of interest as ideal materials for devices in the field of flexible sensing due to their mechanical flexibility and high electrical conductivity; however, conventional conductive hydrogels failed in high toughness, high electrical conductivity, and high recyclability at the same time and have not been widely used. Herein, we reported the used of carboxymethyl cellulose (CMC) and polyacrylamide (PAAM) grafts to form a hydrogel with polyvinyl alcohol (PVA), and the introduction of the conductive polymers polyaniline (PANI) and zinc ions (Zn2+) to obtain PANI/CMC-Zn2+-PAAM/PVA composites. The results showed that the breaking elongation of PANI/CMC-Zn2+/PAAM/PVA hydrogel was 183% and the conductivity was 1.32 S m−1 due to the interaction of chemical covalent bonds and physical crosslinking between molecules. As a wearable strain sensor, the PANI/CMC-Zn2+/PAAM/PVA hydrogel had an impressive sensitivity (GF=2.09 for a tensile strain range of 0%- 80% and GF=4.58 for a tensile strain range of 80%-120%), which can be used for detecting the signals of motion and physiological activities in various parts of the human body. This research will provide a valuable way for the application of hydrogel sensors in the fields of visual human-computer interaction, wearable sensors, visual optical detection and medical health detection.