Screen-printed flexible temperature sensor based on FG/CNT/PDMS composite with constant TCR

This work present the fabrication and characterization of a flexible temperature sensor based on the flake graphite (FG)/carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite. The sensor shows high temperature sensitivity and good linearity. The FG/CNT/PDMS temperature-sensitive films are prepared by the screen printing process. Superior printability of the FG/CNT/PDMS inks is demonstrated by means of rheology. Field emission scanning electron microscope investigation reveals an interpenetrating network structures between the FG and CNT. Moreover, thermal gravity analysis illustrates that the FG/CNT/PDMS temperature-sensitive films have a better thermal stability than that of PDMS blank control film. The temperature-dependent resistance behavior suggests that the temperature coefficient of resistance (TCR) value of the FG/CNT/PDMS films can be manipulated by the mass ratio of FG to CNT. When the mass ratio of FG to CNT is 4:1, the TCR is almost reproducible and maintained at the same level of 0.028 K⁻¹ for repeated thermal cycles. These results indicate that the developed FG/CNT/PDMS composite has potential applications for the flexible temperature sensor.