Publication date: 28th June 2024
Inkjet printing technology has emerged as a promising tool for fabricating bioelectronic devices, offering scalability and accessibility in device manufacturing processes. In this study, we explore the application of inkjet-printed Nafion-gated graphene field-effect transistors (NF-GFETs) for bioelectronics applications. With the exceptional conductivity and biocompatibility of Nafion, NF-GFETs serve as ion-to-electron transducers, enabling precise control over electronic signals and ion transport. We extend our investigation to encompass varying relative humidity levels, mirroring biological conditions, and demonstrate enhanced device performance under humid environments. Inkjet printed Nafion gate exhibits much more gate response compared to the back gate thanks to the large capacitance of the Nafion gate dielectrics. To be more specific, the transconductance of transistors using the Nafion gate is approximately 20 times higher than that of the back gate. The performance of Nafion-gated graphene transistors operating at different RH conditions is compared to vacuum conditions. The results show that under vacuum conditions, the gate response is ineffective. In addition, we can see the shift of the Dirac point to the negative gate voltage direction and reduced hysteresis with increasing RH levels. We then perform the fast measurements (Id response at different frequencies with an applied square waved gate voltage) to simulate physiological signals. Initial tests, conducted with spin-coated Nafion graphene transistors due to equipment limitations, show a good square-wave fidelity up to 100 Hz. We are currently optimizing the device geometry of inkjet-printed Nafion graphene transistors for similar fast measurements.
Acknowledgement: Ky Van Nguyen acknowledges the funding support from a Brain Pool fellowship from the National Research Foundation of Korea (NRF) funded by the Ministry of Education (Grant No. 2022H1D3A2A02063358).