Improvement of Sensitivity and Limit of Detection in a Nanogap Biosensor by Controlling Surface Wettability

Controlling the surface wettability of a bio-sensor improves the sensitivity and limit of detection (LOD) in an electrical label-free detection. The sensing area is treated as hydrophilic and its outer surface is treated as hydrophobic by using a passivation layer composed of CYTOPTM. The hydrophilic sensing area enhances biomolecule interactions between receptors and analytes, whereas the hydrophobic outer sensing region suppresses them. Consequently, the sensitivity and LOD are improved by the increased analyte concentration during the biomolecule interactions. We varied the areal ratio of the hydrophobic region to the hydrophilic region and investigated its effect via detection of cardiac troponin I, which is a biomarker that is used in determining the prognosis of myocardial infarctions. Three-fold of sensitivity and 3 orders of LOD in the hydrophobic passivation were improved over the non-passivation.