A wearable graphene transistor-based biosensor for monitoring IL-6 biomarker

Graphene-based field-effect transistor (GFET) is becoming an increasingly popular biosensing platform for monitoring health conditions through biomarker detection. Moreover, the graphene's 2-dimensional geometry makes it ideal for implementing flexible or wearable electronic devices. If implemented as a wearable biosensor, such technology can non-invasively monitor relevant biomarkers continuously in real-time and alert the user of possible health concerns. As a proof of feasibility, this paper presents a wearable GFET device fabricated on a flexible film that is capable of detecting interleukin-6 (IL-6) protein, a key biomarker implicated in immune responses, in the concentration range of 10 pM to 100 nM. The surface of graphene is modified with target-binding aptamers to ensure analyte selectivity. Our results show that the biosensor measurements were stable with minimum changes when the GFET was bent with a radius of curvature between 1.5 cm and 4.25 cm suggesting robustness of the flexible GFET device. We have also demonstrated continuous real-time monitoring of IL-6 with high sensitivity within the concentration range of 10 pM and 1 nM. Furthermore, a minimum footprint, battery-powered circuit board is also developed that controls the GFET and records the sensor responses in real-time demonstrating the feasibility of becoming a fully standalone and wearable biosensor. The results from this work suggest that the thin film GFET-based biosensor has the potential to be used as a wearable continuous health monitoring device.