Graphene-Enhanced\nScreen-Printed BiFeO₃‑Based Thermistors

Abstract

In\nthis study, serigraphic-grade BiFeO₃-based ink formulations\nare produced and then mixed with graphene to enhance the performances\nof screen-printed thermistor devices. The devices are printed atop\na standard thermally boosted glass-reinforced epoxy (FR-4) substrate\ncoated with interdigitated gold electrodes. The broader operating\ntemperature range of these thermistors makes them compatible with\nstandard printed circuit board (PCB) manufacturing and operating conditions.\nThus, we achieve highly sensitive devices with a temperature coefficient\nof resistance (TCR) of −0.96%/°C, which is the highest\nsensitivity reported yet for any graphene-based thermistor operating\nfrom 25 to 170 °C. The best-performing devices are loaded with\n3.5 wt % graphene. These low-hysteresis and stable thermistors boast\na thermal index (β-coefficient) of 864 K. This optimal graphene\nloading occurs just above the percolation threshold.