Upcycled cellulose pulp from local agricultural waste as a crosslinker in one-pot DLP-printable formulations for ionic wearable sensors

Strain-responsive materials are gaining attention for applications in wearable sensors and flexible electronics, driving the need for sustainable production methods. Herein, cellulose pulp (CP) was extracted from local agricultural waste and dispersed in a photopolymerizable deep eutectic solvent (DES) composed of a hydrated salt and acrylic acid. The treatment with this solvent enables the dispersion of CP with its simultaneous functionalization with acrylic moieties, making it an added-value crosslinker for the DES photopolymerization. The resulting dispersion is suitable for DLP 3D printing, thanks to the cellulose’s crosslinking role and enables the production of 3D complex samples. The printed eutectogel boasts excellent ionic conductivity, and mechanical performance tailored for sensing applications with Gauge Factor of of 0.84 ± 0.04 and 1.45 ± 0.24 in the linear ranges between 0–50% and 50–200% respectively. The eutectogel exhibits exceptional sensitivity to both small (0.02%) and large (above 200%) deformations, that can be tuned through the interplay between the material intrinsic properties and 3D design and allows the device implementation in wearable sensors. Sensing performances are maintained for over twenty weeks, far beyond than the other reported works in cellulose based eutectogels. This work paves the way for the next generation of sustainable, high-performance, and customizable soft electronic materials, able to exploit and valorise local waste, entering the mindset of the circular economy.