Surface Charge Modulation and Reduction of Non-Linear Electrolytic Screening in FET-Based Biosensing

We experimentally investigate the influence of non-linear electrolytic screening by electric double layer (EDL) and its impact on field-effect transistor (FET) sensitivity to charged (bio)molecules. use DNA hybridization a PNA capture probe as model system. By co-depositing positively or negatively blocker molecules together with probes SiO 2 surface FET, we control overall charge modulate strength local ion concentration within EDL. observe FET signal enhancement up 51% when including captured analyte itself swings roughly symmetrically around zero during capture, confirmed zeta potential measurements. Surface plasmon resonance measurements rule out change in density origin sensitivity. This confirms that excess caused large concentration, which increases non-linearly EDL, is responsible for loss bioFETs surface. These experimental findings agree early theoretical works find low be desirable best bioFET performance.