Name: Vijay Kumar Garika ID: 850111295 Degree: PhD Supervisor: Prof. Gil Shalev Seminar Title: Addressing the challenge of solution gating in biological field-effect transistors

Name: Vijay Kumar Garika ID: 850111295 Degree: PhD Supervisor: Prof. Gil Shalev Seminar Title: Addressing the challenge of solution gating in biological field-effect transistors Seminar summary: Biological field-effect transistors (BioFETs) have long been envisioned as a powerful platform for next-generation medical diagnostics. However, a fundamental challenge persists in conventional BioFET operation related to solution-gate. In a FET device the channel current is measured while sweeping the solution gate voltage. This approach presents a critical limitation in BioFETs: the solution gate does not only modulate the current, but also directly affects the electrochemical environment at the sensing interface. Specifically, sweeping the solution gate continuously alters the pH, ion concentrations, and electric fields within the electrical double layer hosting the surface-bound biomolecules, and electrochemical equilibrium cannot be established during sensing. To address this challenge, this study introduces the Meta-Nano-Channel (MNC) BioFET that decouples the solution potential from channel gating. The MNC BioFET enables channel excitation while maintaining solution and biomolecules in electrochemical equilibrium. Building on this approach we pursue real-time, specific, label-free detection of Borrelia burgdorferi s.l. outer surface protein A (OspA), a biomarker for Lyme disease. Sensing is performed in 0.5 µL blood drops with a limit-of-detection of 1 fg/mL, a dynamic range of 8 orders of magnitude, and excellent sensitivity and linearity. Moreover, the sensing is performed, for the first time, in unprocessed whole blood and without pre-measurement washing steps. These results highlight the potential of the MNC BioFET as a robust platform for ultrasensitive diagnostics in complex biological samples, with direct relevance to point-of-care and infectious disease diagnostics.