Adsorption-desorption noise in nanowire FET biosensors

The adsorption-desorption (AD) noise in nanowire FET biosensors is analyzed, which manifests itself in the form of gate voltage fluctuations resulting from the fluctuations of the number of adsorbed particles. The derived theoretical model of the fluctuations takes into account the mass transfer effects. The numerical calculations show that when the mass transfer is slow, the low-frequency amplitude and the corner frequency of the Lorentzian AD noise spectrum obtained by derived expressions are significantly different compared to the same parameters predicted by the model that neglects mass transport effects. The presented analysis enables good estimation of these parameters from the measured noise spectrum, which is important because they are used as the source of information about the analyte concentration and the kinetics of biomolecular interactions.