An ultrathin flexible affinity-based graphene field-effect transistor for glucose monitoring

Wearable glucose sensors, regardless of invasive or non-invasive, show tremendous demands of accuracy, long-term stability, flexibility, and comfortability. Because of the unique structure and excellent electrical performance of monolayer graphene, the graphene field effect transistor (G-FET) has been successfully applied into the fabrication of the high-performance glucose sensor. However, most of the developed G-FET devices are enzymatic, of which the accuracy and the stability usually suffer from the inevitable enzyme deactivation. Besides, they are usually fabricated on solid substrates (e.g., silicon or glass), which severely limit the wearable applications. In this work, an ultrathin flexible affinity-based G-FET is realized for the non-enzymatic glucose detection. The device fabrication was achieved on an adhesive support, which made the device can be easy to peel off and simplify the process. The graphene channel was functionalized using the specific pyrene-1-boronic acid (PBA). As the glucose solution was injected, glucose molecules were recognized by electron-withdrawing PBA molecules to form electron-rich glucose-boronate ester complexes, thus inducing the variation in the conductivity of graphene channel. The fabricated glucose sensor shows a wide detection range of 1 μM-5 mM, a high sensitivity of -0.6695 μA/decade, and a low detection limit of 0.1 μM (S/N = 3). The findings indicate the great potentials of such the ultrathin flexible device for the sensitive detection of small molecules in various biofluids, such as sweat, tear, saliva, and blood.