Region-Functionalized Laser-Induced Graphene Sensor Array for Flexible and Intelligent Multi-Gas Detection

Flexible multi-gas sensor array has promising applications in wearable monitoring, environmental safety and intelligent sensing systems. In this work, a flexible 2 × 2 multi-gas sensor array based on region-functionalized laser-induced graphene (LIG) was developed for room-temperature gas detection and intelligent identification. MXene, MoS2, TiO2 and CuO were selectively introduced into different regions of a polyimide substrate, followed by femtosecond pulsed-laser direct writing to form four functionally differentiated LIG-based sensing units. The porous LIG network simultaneously serves as the conductive pathway, gas-adsorption interface, and sensing electrode, enabling the integration of multiple sensing functions within a single flexible platform. The gas-sensing results show that the array exhibits differential response characteristics toward NH3, H2S, acetone, and ethanol. LIG@MXene exhibited a pronounced and repeatable response toward NH3, whereas LIG@MoS2, LIG@TiO2, and LIG@CuO showed preferential responses toward H2S, acetone, and ethanol, respectively. The distinct response amplitudes and polarities of the four sensing channels provide multidimensional features for gas-condition identification. The device also maintained relatively stable NH3 sensing performance under mechanical bending, with a response retention of approximately 84.2% at a bending angle of 120°. Based on the multidimensional response signals of the four-channel array, a backpropagation neural network (BPNN) was employed for gas-condition identification. The overall correlation coefficient between the network outputs and the numerically encoded target labels reached 0.99974 for the single-gas dataset and 0.94894 for the mixed-gas dataset. This study provides an effective strategy for integrating region-specific material functionalization, flexible laser fabrication, multi-channel sensing, and intelligent gas identification within a single LIG-based sensing platform.