Flexible/wearable resistive gas sensors based on 2D materials

Flexible/wearable gas sensor technology is gaining huge interest in the current era of the Internet of Things for its applications in personal environmental monitoring, healthcare, and safety. In this respect, the resistive gas sensor has received a great deal of attention in the flexible/wearable sensing field owing to its easy read-out mechanism, low power consumption, and simple fabrication with miniaturization. In the last few years, two-dimensional (2D) materials have sparked significant attention in the development of resistive gas sensors on flexible or wearable sensing platforms due to their excellent electrical, physiochemical, and mechanical properties. In this review, recent research advancements in the field of flexible or wearable gas sensors using emerging 2D materials including graphene, transition metal carbides, and nitrides (collectively known as MXenes), phosphorene, and transition metal dichalcogenides (TMDs) are discussed. The sensing performance of the flexible/wearable gas sensors are explained in detail with the relation between 2D sensing materials and various substrates (i.e. polymer, textile, and paper). In addition, gas sensing applications of 2D materials-based flexible/wearable resistive sensors are highlighted with current challenges to future perspectives.