Limonene-thioctic acid-ionic liquid polymer: A self-healing and antibacterial material for movement detection sensor

The healable smart electronic sensor can prolong its service life. Polymers with dynamic disulfide bonds are widely used in healable sensors because of their self-healing properties at room temperature, but the presence of terminal diradicals leads to their instability. Herein, attracted by the favorable reactivity of limonene (LIM) for nucleophilic proton addition, it is chosen to quench thiyl radical to prepare a self-healing polymeric material (poly TA-(EMIM)(ESO4)-LIM) for the sensor by thioctic acid (TA) and 1-ethyl-3-methylimidazolium ethyl sulfate [(EMIM)(ESO4)]. The polymeric material not only displayed long-term stability and moderate strain (640%) but also was equipped with a high adhesive strength towards various substrates. The existence of dynamic disulfide bonds and the hydrogen bonds conferred favorable self-healing capacity of the poly TA-(EMIM)(ESO4)-LIM. The fascinating conductivity sensitivity with gauge factors of 2.34 and 5.12 could be achieved under small deformation (0%−100%) and large deformation (100%−200%), respectively. Meanwhile, the polymeric material could detect the human movement of finger bending, elbow bending, and wrist bending, where a stable conductivity sensitivity could maintain after several cycles. Moreover, based on the natural and outstanding antibacterial activity of LIM, the antimicrobial capacity of the polymeric material is further enhanced (kill efficiency > 90%). These fascinating features make the poly TA-(EMIM)(ESO4)-LIM displayed great potential as an epidermal electronic for detecting human movement.