Smart conductive organogel based on gluten and guar gum for flexible wearable sensors

Conductive organogels derived from natural biopolymers offer significant potential for wearable and stretchable sensing devices due to their renewable, non-toxic, biocompatible, and biodegradable properties, as well as their outstanding flexibility and conductivity. Currently, the integration of smart properties such as good mechanical properties, self-healing capability, and high strain sensitivity for fabricating hydrogel-based strain sensors remains challenging. Herein, we developed guar gum/gluten-based organogels crosslinked via dynamic covalent bonds. The effect of three additives, such as tannic acid (T), glycerol (G), and sodium chloride (NaCl) on organogel properties was studied. The addition of TA remarkably enhanced tensile strength, self-adhesive capabilities, and conductivity. Additionally, the incorporation of NaCl within the range of 0-5 wt% improved self-adhesion ability. Moreover, the presence of glycerol in the strain sensors decreased self-healing time. The optimal composition of three additives was found at 3.75 wt% T, 30 vol% G, and 5 wt% NaCl. This composition exhibited a gauge factor (GF) of 0.6% at a stretchability of 665%. After storing the organogel for 7 days, the sample demonstrated long-term stability in self-healing, with an efficiency of 98%.