Recent Advances in Laser‐Induced Graphene‐Based Gas Sensors: From Sensing Mechanisms to Biomedical Applications

Direct laser irradiation of carbonaceous precursors such as polyimide and wood is a scalable and efficient method to produce a 3D porous graphene structure, noted as laser-induced graphene (LIG). The electrical and chemical properties of the LIG can be optimized for the target application by mixing or doping with transition metal dichalcogenides or others to form LIG nanocomposites. Fine-tuning these properties has led to extensive use in sensing various gaseous biomarkers from the human body or the environment. This review first discusses the gas-sensing mechanism of LIG and its nanocomposites, followed by a summary of different fabrication methods and performance characteristics. It also examines recent developments in soft functional packaging, such as semi-permeable membranes or hermetic encapsulations, to provide the sensors with moisture-resistance or signal decoupling capabilities. Despite the efforts to further improve the gas sensing characteristics, the recently developed wireless and standalone gas sensing platforms highlight a different opportunity for the commercialization of wearable gas sensors. Strategies executed by other gas sensors have been proposed to mitigate the problems and challenges faced by the LIG-based nanocomposite gas sensors. This review serves as a comprehensive reference on LIG-based nanocomposite gas sensors, from fundamentals of sensing mechanisms to real-life applications.