Flexible and Transparent Gas Molecule Sensor Integrated with Sensing and Heating Graphene Layers

Graphene leading to high surface‐to‐volume ratio and outstanding conductivity is applied for gas molecule sensing with fully utilizing its unique transparent and flexible functionalities which cannot be expected from solid‐state gas sensors. In order to attain a fast response and rapid recovering time, the flexible sensors also require integrated flexible and transparent heaters. Here, large‐scale flexible and transparent gas molecule sensor devices, integrated with a graphene sensing channel and a graphene transparent heater for fast recovering operation, are demonstrated. This combined all‐graphene device structure enables an overall device optical transmittance that exceeds 90% and reliable sensing performance with a bending strain of less than 1.4%. In particular, it is possible to classify the fast (≈14 s) and slow (≈95 s) response due to sp²‐carbon bonding and disorders on graphene and the self‐integrated graphene heater leads to the rapid recovery (≈11 s) of a 2 cm × 2 cm sized sensor with reproducible sensing cycles, including full recovery steps without significant signal degradation under exposure to NO₂ gas.