Graphene cellulose hybrids for biodegradable flexible sensing devices

Paper-based sensors have emerged as a groundbreaking class of analytical devices, offering affordable, biodegradable, and flexible platforms for a broad range of applications, including environmental monitoring (e.g., heavy metals, PFAS, and microplastics detection), medical diagnostics (such as procalcitonin and glucose monitoring), food safety (like ammonia detection), and wearable electronics (for strain, pressure, and humidity sensing). This review looks at how using cellulosic-based materials with advanced nanomaterials-especially graphene and its variations-can improve the sensitivity, conductivity, and durability of sensors. The deploy of graphene-based electrodes, such as reduced graphene oxide (rGO), laser-induced graphene (LIG), and graphene-molybdenum disulphide (Gr/MoS₂) composites, has developed devices with high responsiveness (up to 1.38 × 10^-7 µA L^-1 µg^-1), low detection inhibits (as low as 1.36 pM), excellent mechanical flexibility, and strong thermal equilibrium (up to 700 °C). These developments highlight the immense potential of graphene-paper hybrid systems for constructing the next generation of environmentally friendly and multipurpose sensors that can tackle new worldwide issues in smart packaging, public health, the Internet of Things (IoT), and sustainable electronics.