Beyond Charge: Field‐Effect Transistors in Multimodal Biosensing Platforms for Biomolecular Interaction Studies

Field‐effect transistors (FETs) have long been recognized as highly promising platforms for label‐free and real‐time biosensing, offering a route toward compact, low‐cost, and portable devices. Despite their earlier development compared to other transducer technologies like surface plasmon resonance (SPR)‐based biosensors, their commercialization has been hindered due to challenges in stability, reliability, and signal interpretation. Four decades after the introduction of the first FET biosensor, FET‐based multi‐transducer systems have been gaining popularity, as they can simultaneously probe different properties of a target‐receptor interaction. These hybrid approaches extend the sensing capabilities of FETs beyond detection of charge density distribution changes. The combination provides richer insights into biomolecular interactions at interfaces and yields data that exceeds the scope of the individual methods alone. This review highlights the central role of charge distribution in surface biomolecular recognition and surveys the progress achieved by merging FETs with diverse transducers. Particular emphasis is placed on SPR‐FET‐based dual‐mode systems which showcase both the benefits and challenges of such platforms.