Lumped-Capacitive Modeling and Sensing Characteristics of an Electrolyte-Gated FET Biosensor for the Detection of the Peanut Allergen

Abstract

Si-based electrolyte-gated transistors (EGTs) have been investigated to achieve high sensitivity and a low detection limit (LOD). Here, a lumped-capacitive model was applied to analyze the influence of receptor–target conjugates on the sensing performance. The voltage-related sensitivity is mainly determined by the effective dipole potential ( $V_{DP,EFF}$ ), the effective capacitance of the functionalization layer ( $C_{FN,EFF}$ ), and the total charge density in the channel ( $Q_{S}$ ) related to the operating regime. In an n-type EGT, the sensitivity is enhanced as the device is operated in the subthreshold regime with a positive $V_{DP,EFF}$ and a small $C_{FN,EFF}$ . The influence of the $V_{DP,EFF}$ and $C_{FN,EFF}$ was experimentally evaluated by detecting the peanut allergen (PA) using the fabricated n-type Si-EGTs. A higher sensitivity and a lower LOD could be achieved in the subthreshold regimes than in the linear regime. These results suggest that the proposed model is very useful to optimize the sensing characteristics of Si-based EGT for biosensing applications.

Keywords

• Capacitance
• dipole moment
• electrolyte-gated transistor
• limit of detection
• peanut allergen
• silicon nanonet