Flexible Sensors for Hydrogen Peroxide Detection: A Critical Review.

Hydrogen peroxide (H2O2) is a common chemical used in many industries and can be found in various biological environments, water, and air. Yet, H2O2 in a certain range of concentrations can be hazardous and toxic. Therefore, it is crucial to determine its concentration at different conditions for safety and diagnostic purposes. This review provides an insight about different types of sensors that have been developed for detection of H2O2. Their flexibility, stability, cost, detection limit, manufacturing, and challenges in their applications have been compared. More specifically the advantages and disadvantages of various flexible substrates that have been utilized for the design of H2O2 sensors were discussed. These substrates include carbonaceous substrates (e.g., reduced graphene oxide films, carbon cloth, carbon, and graphene fibers), polymeric substrates, paper, thin glass, and silicon wafers. Many of these substrates are often decorated with nanostructures composed of Pt, Au, Ag, MnO2, Fe3O4, or a conductive polymer to enhance the performance of sensors. The impact of these nanostructures on the sensing performance of resulting flexible H2O2 sensors has been reviewed in detail. In summary, the detection limits of these sensors are within the range of 100 nM-1 mM, which makes them potentially, but not necessarily, suitable for applications in health, food, and environmental monitoring. However, the required sample volume, cost, ease of manufacturing, and stability are often neglected compared to other detection parameters, which hinders sensors' real-world application. Future perspectives on how to address some of the substrate limitations and examples of application-driven sensors are also discussed.