Capacitive field-effect biosensors loaded with intact plant virus particles: modelling and experimental data

Plant viruses are considered one of the main contributors to crop losses in the agricultural industry and thus induce high economic costs worldwide. The best strategy to slow down the spread of plant virus infections and prevent crop failures is to make an early and reliable diagnosis and provide prompt treatment. Electrolyte-insulator-semiconductor capacitors (EISCAP) represent an attractive transducer architecture for label-free electrostatic detection of virus particles by their intrinsic charge. In this work, a capacitive model of an EISCAP sensor loaded with negatively charged tobacco mosaic virus (TMV) particles is presented. In the developed model, the adsorbed TMV particles are assumed as local gates with dimensions in the nano- to sub-micrometer range. The impact of TMV surface coverage on the sensor characteristics of SiO₂-gate EISCAPs was studied theoretically and experimentally. The observed EISCAP signal correlates well with the coverage of loaded TMV particles evaluated from scanning electron microscopy images of the SiO₂-gate surface.