The coupling of ligand‐stabilized gold nanoparticles with field‐effect devices offers new possibilities for label‐free biosensing. In this work, we study the immobilization of aminooctanethiol‐stabilized gold nanoparticles (AuAOTs) on the silicon dioxide surface of a capacitive field‐effect sensor. The terminal amino group of the AuAOT is well suited for the functionalization with biomolecules. The attachment of the positively‐charged AuAOTs on a capacitive field‐effect sensor was detected by direct electrical readout using capacitance‐voltage and constant capacitance measurements. With a higher particle density on the sensor surface, the measured signal change was correspondingly more pronounced. The results demonstrate the ability of capacitive field‐effect sensors for the non‐destructive quantitative validation of nanoparticle immobilization. In addition, the electrostatic binding of the polyanion polystyrene sulfonate to the AuAOT‐modified sensor surface was studied as a model system for the label‐free detection of charged macromolecules. Most likely, this approach can be transferred to the label‐free detection of other charged molecules such as enzymes or antibodies.

Nanoparticles are recognized as highly attractive tunable materials for designing field-effect biosensors with enhanced performance. In this work, we present a theoretical model for electrolyte-insulator-semiconductor capacitors (EISCAP) decorated with ligand-stabilized charged gold nanoparticles. The charged AuNPs are taken into account as additional, nanometer-sized local gates. The capacitance-voltage (C–V) curves and constant-capacitance (ConCap) signals of the AuNP-decorated EISCAPs have been simulated. The impact of the AuNP coverage on the shift of the C–V curves and the ConCap signals was also studied experimentally on Al–p-Si–SiO2 EISCAPs decorated with positively charged aminooctanethiol-capped AuNPs. In addition, the surface of the EISCAPs, modified with AuNPs, was characterized by scanning electron microscopy for different immobilization times of the nanoparticles.

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In comparison to single‐analyte devices, multiplexed systems for a multi‐analyte detection offer a reduced assay time and sample volume, low costs and high throughput. In this work, a multiplexing platform for an automated quasi‐simultaneous characterization of multiple (up to sixteen) capacitive field‐effect sensors by the capacitive‐voltage (C−V) and the constant‐capacitance (ConCap) mode is presented. The sensors were mounted in a newly designed multi‐cell arrangement with one common reference electrode and electrically connected to the impedance analyzer via the base station. A Python script for the automated characterization of the sensors executes the user‐defined measurement protocol. The developed multiplexing system was tested for pH measurements and the label‐free detection of ligand‐stabilized, charged gold nanoparticles.This article is protected by copyright. All rights reserved.