Important physical processes to consider when modelling the response of DNA biotransistors

In the recent past, several models that predict the response of DNA biosensors have been proposed. These models produce approximate, order-of-magnitude estimates of the response of the DNA biosensor. Therefore, it remains an important task to identify different factors that allow for more accurate estimates of the response of DNA biosensors to be calculated. In this paper, we identify three such factors: the role of steric interactions between ions in a solution; the permeability of single-stranded DNA to ions; and the effect of the buffer solution. Using mean-field finite-element calculations, we study these effects numerically and we find out that they can all have a large impact on the response of the DNA biotransistor (BioFET). The impact is large enough to re-cast the question "which phenomenon is most responsible for the sensed DNA hybridization signal?" Our results here show that the factors studied are as important to the sensed signal as the charge that the target oligonucleotide possesses.