Biosensing Interfaces and Parameters in Field-Effect Transistor-Based Biosensors

In developing a biosensor, we consider the design criteria based on its three components, namely, the biological target, signal transduction interface, and detection device. Among the detection devices, a platform based on an electronic device with field-effect transistor (FET) biosensors is suitable for use in miniaturized and cost-effective systems to directly measure biological samples because the FET biosensors allow the direct detection of intrinsic ionic and biomolecular charges in principle, which contributes to label- and enzyme-free biosensing. Such miniaturized electronic devices can be easily equipped with a wireless function and attached to the body, which is available for wearable biosensors to detect biomarkers in a blood-sampling-free manner (i.e., tears, sweat, and saliva). Here, it is very important to determine how the change in the density of charges based on biomolecular recognition events is directly transduced into electrical signals at the signal transduction interfaces, regardless of the wearability of FET biosensors. Such bio/device interfaces are <i>chemically synthesized</i>, <i>physically and chemically structured</i>, and <i>biologically induced</i> to control the biosensing parameters such as specificity, selectivity (<i>S</i>), binding constant (<i>K</i>_a), limit of detection (LOD), signal-to-noise ratio (S/N), and biocompatibility with respect to the biological target, although the chemically synthesized electrical interfaces are also useful as the signal transduction interfaces for the flexible wearable biosensors [1]. In particular, the increase in <i>K</i>_a for the target biological target, which results in the enhancement of <i>S</i> and LOD, becomes a key challenge for enzyme-free interfaces, and then biocompatible materials may be chosen for the signal transduction interfaces. On the other hand, various semiconductor materials have been recently applied as the channel of FET biosensors. Therefore, the diversity of signal transduction interfaces broadens the possibility of developing novel biosensing devices, in parallel with the development of new channel materials for the FET biosensors. The optimal biosensing parameters are effectively provided by the diverse signal transduction interfaces for the practical use of FET biosensors. In this talk, distinctive signal transduction interfaces for FET biosensors are introduced, categorized as chemically synthesized, physically structured, and biologically induced interfaces, focusing on the above biosensing parameters.<br/><b>References</b><br/>[1] Sakata, T. [Review Article] <i>Commun. Chem.</i> 2024, 7, 134239.