Nickel oxide/graphene-based temperature sensor: Flexible design with low processing temperatures and high stability

This study presents the development and characterization of a flexible temperature sensor based on a composite of nickel oxide (NiO) and graphene, optimized for environmental monitoring. The sensor exhibits Negative Temperature Coefficient (NTC) behavior, with electrical resistance decreasing as temperature increases. The PS concentration significantly influenced the sensor's response, with higher concentrations leading to increased temperature sensitivity (higher β-values) but also introducing nonlinearity. We tailored the sensor's sensitivity and thermal response, achieving a β-value range from 1121 K to 2354 K between the temperature range −10℃ and 50℃. The sensor demonstrated rapid response time of 20 seconds, low hysteresis of 3.2 kΩ, a good resolution of ± 0.5°C, high repeatability across multiple temperature cycles with temperature range of −10℃ and 50℃, and high sensing stability over two months with a mean B-value of 2338.8 K and standard deviation of 36.46 K. It also showed enhanced stability against humidity up to 45 % RH. Long-term performance tests confirmed the sensor's robustness, with minimal drift in electrical resistance over 10 hours and consistent β-values over two months. The sensor was successfully applied to monitor temperature changes in controlled environments, demonstrating its potential for reliable, low-cost temperature monitoring in various applications.