High-performance flexible temperature sensor based on heteroatom doped laser-reduced graphene oxide

Abstract Wearable electronics and the Internet of Things (IoT) progression create a pressing desire to develop flexible sensors for healthcare monitoring and industrial applications. This study presents a new scalable and low-cost approach for fabricating high performance and flexible temperature sensors based on sulfur (S) and nitrogen (N) co-doped laser-reduced graphene oxide denoted as (LRSNGO) for wearable electronics. A handy visible laser engraver machine was fabricated for simultaneous co-doping, patterning, and photothermal reduction of graphene oxide (GO) films. SEM, XRD, and Raman spectroscopy results confirmed the effective photothermal reduction of GO and unveiled structural characteristics enhancements due to nitrogen and Sulfur co-doping. XPS analysis endorsed the efficient electron donative and defects curative integration of nitrogen and Sulfur heteroatoms into the graphitic lattice. The LRSNGO exhibited an electrical conductivity of 847.9 S/m significantly higher than the nitrogen-doped and the pristine LRGO. The LRSNGO also demonstrated the best thermal sensitivity, with a temperature coefficient of resistance (TCR) of − 0.233%/⁰C, which is ~ 117% higher than the pristine LRGO sensor. These results were associated with a fast response time of 3.5 s, excellent thermal stability, and outstanding mechanical stability and flexibility. LRSNGO sensor was tested for live monitoring of human body temperature demonstrated quick response and precision with an almost consistent body temperature reading. All characterization results are comprehensively discussed and interpreted throughout the study. Graphical abstract