A Corn-Based Electrically Conductive Glue for Integration of Edible Electronics

Edible electronics leverages the electronic properties of food-grade materials to create non-toxic technologies that can be either environmentally degraded or digested by the body after the completion of their function. Various edible electronic components have been recently proposed, and their integration into more complex circuits and systems is urgently needed for point-of-care devices. In this context, developing a safe technology for interconnecting edible components is crucial. To this aim, here an edible electrically conductive adhesive made from zein, an edible protein derived from corn, and activated carbon, a food additive, are reported. Different formulations are proposed depending on the ratio between adhesive binder (zein) and electrically conductive filler (activated carbon), evidencing a trade-off between resistivity and adhesion, passing from a 3 × 10³ Ω cm resistivity and 2 MPa lap shear adhesion strength to 5 × 10² Ω cm and 0.5 MPa values upon increasing the filler content. As a proof-of-concept, the conductive adhesive is validated in different applications relevant to edible electronics, such as mounting devices on top of innovative edible substrates, interconnecting state-of-the-art edible batteries, and conforming highly adhesive electrodes for fruit monitoring.