The role of surface charge and binding properties in silicon-based field effect nanowire biosensors

This modeling work examines the critical role of nanowire surface properties in its DNA sensing performance in terms of both signal levels and input dynamic ranges. Such properties include surface charge group density, oxide thickness and oligomer surface density, charges and energetic heterogeneity. The presence of surface charge groups are shown to contribute to additional charge screening. The use of neutral receptors (PNAs) instead of ssDNAs improves the signals significantly due to nonlinear charge screening. Based on correlations with experimental data, it is indicated that the heterogeneity of DNA binding energetics is crucial in determining the input dynamic ranges.