Self-Adhesive, Highly Linear Flexible Strain Sensor Designed Using the Thermal Response Countermeasure Principle for a Wide Temperature Domain

Flexible strain sensors are of great significance in achieving high sensitivity monitoring, expanding the application scope of intelligent devices, and promoting the innovation of human-computer interaction technology. However, variations in environmental temperature frequently lead to signal drift in strain sensing, compromising the stability and accuracy of the measurements. This study exploits the negative temperature coefficient of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) in its temperature response. Through constructing the network cross-linking structure, introducing hydrogen bonding, and modulating metal coordination, the thermal expansion mismatch between PEDOT:PSS and the matrix was effectively mitigated. By balancing the antagonistic effects of the "negative temperature effect" (NTC) and "thermal expansion effect" (PTC), the insensitive characteristic of the sensing material to temperature changes was achieved. The temperature coefficient of resistance (TCR) of the sample decreased from 40.29 to 0.45%/K. Meanwhile, the modified samples exhibit superior strain-sensing performance, characterized by a broad strain range of 0-50%, excellent linearity, and stable signal output, which is attributed to their self-adhesive property. These samples demonstrate exceptional stability and durability, maintaining a consistent strain-sensing signal after undergoing over 2000 stretching-recovery cycles. Consequently, this study successfully developed a temperature-insensitive flexible strain-sensing material. The sensor's temperature insensitivity and its ability to stably monitor strain emphasize its significant potential for applications in variable temperature environments, particularly in human motion monitoring and health monitoring.