Reliability Study of Nanoporous Silicon Oxide Impedance Biosensor for Virus Detection: Influence of Surface Roughness

The reliability issues of biosensors have been primarily attributed to the stability and degradation problems of biorecognition elements. However, a critical factor that has never been considered is the time-related device integrity with respect to the interfacial behavior of the material under prolonged exposure to buffer solution at a low temperature. In the presence of electrolyte, the interfacial properties of a particular material are expected to depend largely on surface roughness. In this paper, we have fabricated thick and stoichiometric nanoporous silicon oxide with varying surface roughness by controlling the ratio of hydrofluoric acid and dimethyl sulfoxide during anodic etching. The impact of surface roughness on the degradation of impedance characteristics during virus detection in blood has been studied extensively after different preservation time in buffer solution. It has been observed that reliability (i.e., repeatability) is significantly better for surfaces with higher roughness, but response magnitude and sharpness of sensitivity peak improve with lower surface roughness.