A Carbon-Based NTC Resistive Temperature Sensor for Edible Electronics

A negative temperature coefficient (NTC) resistive sensor implemented using only food-grade materials, namely, activated carbon (AC), gelatin candy, gold, ethyl cellulose, and beeswax, was implemented. We envision that this sensor might find future applications in measuring temperature within the gastrointestinal (GI) tract. Differently from other edible implementations typically based on ionic conductivity, the device herein presented leverages the electronic conductivity of AC and therefore benefits from a simple readout circuit. The sensor features a sensitivity of −0.32% °C−1 and high linearity within the range $5~^{\circ }$ C– $50~^{\circ }$ C. Comparative analysis with a commercially available component reveals analogous functional output. The inherently safe-to-eat feature of the component shows a feasible pathway to miniaturized digestible platforms for GI tract monitoring, as well as sustainable solutions for agrifood and environment monitoring purposes.