Highly sensitive graphene-based chemical and biological sensors with selectivity achievable through low-frequency noise measurement — Theoretical considerations

We have developed a theory of the low-frequency noise caused by interaction of the analyte with the active area of chemical and biological sensors. The main result is an analytical expression for the spectral density of the fluctuations of the number of particles adsorbed onto the sensing surface, taking into account the processes of mass transfer through the sensor reaction chamber, adsorption and desorption, and surface diffusion of adsorbed particles. The performed numerical calculations show good agreement with the experimental data from the literature, obtained for a graphene-based gas sensor. The derived theory contributes to the theoretical basis necessary for the development of a new method for the recognition and quantification of analytes, based on the measured noise spectrum.