Temperature Coefficient of Resistance of Transferred Laser-Induced Graphene

Laser-induced graphene (LIG) has attracted considerable attention as an electrode and sensor in flexible and stretchable devices. For instance, resistive temperature sensors have been developed by using a LIG conductor as an active component. However, despite the evidence that LIG can be used as a temperature sensor, fundamental analyses confirming that LIG is a temperature sensor material are still required. Therefore, this study investigates the temperature coefficient of resistance (TCR) of a transferred LIG in stretchable elastomers. To remove the effect of thermal expansion on elastomers, elastomers with different coefficients of thermal expansion (CTE) values are used, and the temperature responses of LIG in these elastomers are measured. Furthermore, to calibrate the resistance change caused by thermal-expansion-induced strain, strain effects are characterized by stretching the films. Combining the results reveals that the TCR of the transferred LIG was ca. −0.44%/°C, and the sensitivity depended on LIG depth location.