Scalable Wearable and Biocompatible Temperature Sensor: Integrating Laser-Reduced Graphene Oxide on Chitosan-PEG Membranes

Abstract

Flexible, cytocompatible, scalable temperature sensors are essential for bioelectronic devices. Here, a flexible sensor is fabricated using a chitosan–poly(ethylene glycol) (CS–PEG) matrix embedded with laser-reduced graphene oxide (LrGO). Laser-assisted reduction enhances conductivity and generates a stratified, porous microstructure that supports efficient percolation while maintaining flexibility. The sensor shows a stable, highly sensitive thermal response, with a temperature coefficient of resistance (TCR) of − 1 . 174 %◦C − 1 and a sensitivity of − 1457 . 02 Ω◦C − 1 across 30◦C to 90◦C . Impedance spectroscopy shows that the resistive configuration at 500Hz yields an almost linear response (R2 = 0.996), while capacitive behavior and humidity variations ( 30 %to 90 % RH) induce minor impedance changes ( < 15%). Under a 30◦C - 60◦C - 30◦C step, the device shows reversible electrical changes, with a response time of 43 s , recovery of 355 s , minimal hysteresis ( < 1 . 1 % ), and stable performance over 48 h . Bending tests up to 100 % strain for 200 cycles produce moderate resistance variation (R/R0 ≤ 1.88), confirming mechanical robustness. On-skin measurements from 22◦C to 35 . 3◦C show a ≈22 % resistance decrease. Charge-transport analysis agrees with Mott’s hopping model. Cell-culture assays confirm high viability ( > 90 % ). The scalable, solvent-free, metal-free fabrication highlights the CS–PEG–LrGO sensor as a promising platform for wearable biosensing.