Graphene Transistor-Based Printable Electronics for Wearable Biosensing Applications

Graphene 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. By using a GFET platform as a biosensor, users can easily monitor numerous health conditions. A sweat-based biosensor can non-invasively monitor levels of proteins in the body and alert the user to possible issues such as a steep increase or decrease in a particular protein. By creating a platform that can be used as a wearable biosensor, it allows for rapid results and a cheaper way to provide clinical quality data about one’s health conditions. This thesis presents a novel approach for creating a low cost, reliable and selective, wearable biosensor for real-time observation and tracking of the levels of the protein biomarker Interleukin-6 (IL-6). A printable graphene transistor-based biosensor is created by using a PCB printer on a flexible Kapton substrate. The conductive channel of the GFET is created using a chemical vapor deposition (CVD)-grown graphene layer. By functionalizing (or modifying) the graphene surface with biorecognition elements such as antibodies or aptamers in the channel of the device, the GFET can operate as a biosensor. When various levels of IL-6 were introduced into the GFET device, the target proteins bind to the aptamers causing a change in the charge carrier concentration. The device is able to monitor in real-time the levels of IL-6 by observing the drain-to-source current of the GFET which correlates to the IL-6 concentration being measured. The device implemented contains an integrated current meter which is one of the building blocks for creating a wearable electronic biosensor

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\u27s 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