Monolayer Graphene Transfer on a Multilayered Flexible Substrate for Biosensor Fabrication

Graphene has been very popular for biosensing applications due to its unique electrical, electrochemical, and optical properties. Transferred graphene has been used extensively in various applications but the transfer process requires careful consideration for a high-quality sheet transfer. In this direction, this letter reports a transfer technique of monolayer graphene to a flexible multilayered substrate of polyethylene terephthalate and Polydimethylsiloxane (PDMS). In order to demonstrate the application of the transferred graphene for biosensing, two silver electrodes are printed on its surface to fabricate a glucose sensor. Graphene surface functionalization is carried out with glucose oxidase by a linker molecule 1-pyrenebutyric acid N-hydroxysuccinimide ester for enzymatic detection of D-glucose. The functionalized graphene exhibits considerable stability in the sensing performance. The sensor is characterized for 75–200 mg/dl glucose concentration. A sixfold change in response is observed for 200 mg/dl glucose. The observed average sensitivity of the sensor is found to be 3.23%/mg/dL. This letter demonstrates an optimized technique of graphene transfer for a biosensing application. This transfer technique has the potential in the development of affordable flexible graphene sensors for on-site disease diagnosis.