Adsorption–desorption noise in microfluidic biosensors operating in multianalyte environments

Abstract

We present a theoretical model of adsorption–desorption (AD) noise in microfluidic biosensors operating in multianalyte environments. This noise is caused by the stochastic nature of the processes that generate the sensor response: reversible adsorption of n analytes coupled with mass transfer (convection and diffusion) of analyte particles through the microfluidic channel to and from the surface binding sites. The parameters of the obtained analytical expression for the AD noise power spectral density, determining the shape of the noise spectrum, contain information on the concentrations of all the adsorbing species, their association and dissociation rate constants, mass transfer coefficients and molecular masses. The AD noise spectrum, therefore, offers additional data about multiple analytes, apart from those obtained by the commonly used time domain analysis of sensor response. Therefore the derived model of AD noise contributes to the theoretical basis necessary for the development of new methods for determination of target analyte parameters in complex samples or even for simultaneous detection of multiple analytes using a single sensor, based on the measured noise spectrum.