A Flexible Bimodal Pressure–Temperature Sensor With 3-D Sandwich Structure and Thermal Drift Mitigation

Flexible bimodal pressure-temperature sensors, particularly those using piezoresistive/thermosensitive mechanisms, face challenges such as spatial signal interference and complex signal processing. Additionally, thermal drift in conductive fillers like carbon nanotubes (CNTs), although often negligible in narrow-range applications like human monitoring, significantly affects sensor performance and limits broader industrial applicability. In order to address these issues, this study proposes a novel flexible bimodal pressure-temperature sensor with a 3-D “sandwich” structure, enabling simultaneous monitoring of temperature ( $20~^{\circ }$ C– $125~^{\circ }$ C) and pressure (0.02–500 kPa). The temperature sensor employs a negative temperature coefficient (NTC) thermistor, while the pressure sensor features a novel composite design integrating CNT materials with a sponge-microhemisphere structure. The 3-D layered structure and innovative pressure sensor design resolve spatial signal interference, enhance mechanical robustness, and achieve high sensitivity (2.714 $\text{kPa}^{-{1}}$ ), fast response (~78 ms), wide monitoring range, and long-term durability (over 10000 cycles). The thermal drift of CNT-based piezoresistive fillers is, furthermore, effectively mitigated using a backpropagation neural network (BPNN), which also addresses the complex signal processing issue, achieving an exceptional ${R} ^{{2}}$ value of 0.9975. This compensation method provides valuable guidance for addressing thermal drift in similar conductive fillers and demonstrates broad applicability. The proposed sensor design significantly broadens the application scope of flexible bimodal sensors, offering robust solutions for industrial scenarios such as thermal runaway detection in lithium-ion batteries, along with potential uses in environmental monitoring and smart manufacturing.