An Ultraflexible and Transparent Graphene-Based Wearable Sensor for Biofluid Biomarkers Detection

An ultraflexible and transparent graphene-based field-effect transistors (GFET) wearable nanosensor is presented for detection of body fluid-biomarkers. The nanosensor is functionalized with a receptor that can specifically bind with the biomarker, resulting in a detectable change in the carrier concentration of the graphene. After recovery from 100 cycles of deformations (bending at radii 175 µm, folding at 150°, and shrinking at 50%), no visible mechanical damage is observed, and electrical properties of the nanosensor are also highly consistent. L-cysteine, associated with various diseases, is chosen as the biomarker to demonstrate the detection capability of the sensor. The nanosensor is capable of consistently and reliably detecting L-cysteine with a limit of detection of 0.022 × 10⁻⁶ m in undiluted human sweat and 0.043 × 10⁻⁶ m in artificial tears. The sensor is fabricated from the 1 µm transparent polyethylene glycol terephthalate substrate and WO₃/Au/WO₃ electrode (transparency of 81%), and it can be mounted on the eyeball in tear detection without visual influence. These results demonstrate that the ultraflexible and transparent GFET wearable nanosensor can potentially be helpful in medical detection applications.