Ambient molecular water accumulation on silica surfaces detected by a reflectance interference optical balance

Xuefeng Wang, Ming Zhao, David D. Nolte

Research output: Contribution to journalArticle

5 Scopus citations


Water is a persistent background in virtually all biosensors, yet is difficult to quantify. We apply an interferometric optical balance to measure water film accumulation from air onto several types of prepared silica surfaces. The optical balance uses in-line common-path interferometry with balanced quadratures to measure the real-time accumulation of molecular films. The accumulated water thickness is sensitive to ambient conditions, with thicknesses that vary from picometers up to nanometers, even on hydrophobic silanized surfaces. These results demonstrate that water adsorption contributes an excess signal in dry label-free protein microarray optical biosensors and presents a fundamental limit to assay sensitivity.

Original languageEnglish (US)
Article number183702
JournalApplied Physics Letters
Issue number18
StatePublished - Nov 1 2010


ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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