Electrostatic-Enriched Rapid and Ultrasensitive Detection of Allergic Conjunctivitis Biomarker Ige in a Top-Gated Silicon Nanowires Fet Biosensor

Field-effect transistor (FET)-based biosensors typically rely on passive diffusion for target capture, which limits sensitivity and prolongs detection. Here, we present a silicon nanowires (SiNWs) FET biosensor integrated with a top-gate structure for implementing the electrostatic enrichment of biomarkers, whereby an externally applied electric field drives them toward the sensing interface to enhance capture efficiency and reduce response time. Unlike external liquid-gate electrodes that repel targets with poor enrichment, our top gate at the sensing interface enables efficient electrostatic enrichment. As a result, the biosensor for detecting$\operatorname{IgE}$, the biomarker of allergic conjunctivitis, achieves a 448 % increase in response amplitude, a 62 % reduction in response time, and a 454 % improvement in signal-to-noise ratio (SNR). Importantly, the detection limit (LOD) is reduced from$0.57 \text{pg} / \text{mL}$to$0.038 \text{pg} / \text{mL}$, enabling rapid and ultrasensitive detection of IgE.