Thin-Film Devices on Flexible and Unobtrusive Cellulose for Sustainable Temperature Sensing

Abstract

Despite remarkable progress in flexible electronics, the reliance on nonbiodegradable polymers and energy-intensive fabrication processes continues to impede their environmental compatibility and long-term viability. To address this stark sustainability concern, recent research efforts have pivoted toward the exploration of eco-friendly materials with low carbon footprint. In pursuit of this objective, we demonstrate the fabrication of thin-film resistance temperature detectors (RTDs) and thin-film thermistor sensors on a triacetyl cellulose (TAC) film. These devices are characterized in a temperature range from $25\,^{\circ }$ C to $75\,^{\circ }$ C, demonstrating average sensitivity of 0.21%/°C ${}^{-{1}}$ for the Cu-based RTDs, 0.065%/°C ${}^{-{1}}$ for Mo-based RTDs, and −0.26%/°C ${}^{-{1}}$ for Mo/indium gallium zinc oxide (IGZO) based thermistors. The performance of all devices is further evaluated under cyclic thermal stress and varying humidity conditions. Furthermore, device performance is demonstrated under applied mechanical strain, retaining reliable functionality down to 8 mm bending radii. Finally, Mo-based RTDs and thermistor sensors revealed transient behavior in deionized water after 26 and 30 h, respectively. The finding highlights the potential of a cellulose-based TAC substrate for integration with thin-film devices, enabling reusability and environmental sustainability for green electronic applications while contributing to the minimization of electronic waste.