Abstract

The bio-optical compact disk (BioCD) is an optical biosensor that performs common-path molecular interferometry of patterned proteins on a disk spinning at high speed. The common-path configuration makes it ultrastable and allows surface height precision below 10 pm. In this paper we show that two complementary interferometric quadrature conditions exist simultaneously that convert the modulus and phase of the reflection coefficient, modulated by protein patterns on the disk surface, into intensity modulation at the detector. In the far field they separate into spatially symmetric and antisymmetric intensity modulation in response to the local distribution of protein. The antisymmetric response is equivalent to differential phase-contrast detection, and the symmetric response is equivalent to in-line (IL) common-path interferometry. We measure the relative sensitivities of these orthogonal channels to printed protein patterns on disk structures that include thermal oxide on silicon and Bragg dielectric stacks. The scaling mass sensitivity of the IL channel on oxide on silicon was measured to be $0.17\text{pg}/\text{mm}$.

© 2007 Optical Society of America

Combined fluorescent and interferometric detection of protein on a BioCD

Xuefeng Wang, Ming Zhao, and D. D. Nolte
Appl. Opt. 47(15) 2779-2789 (2008)

Differential phase-contrast BioCD biosensor

Ming Zhao, Wonryeon Cho, Fred Regnier, and David Nolte
Appl. Opt. 46(24) 6196-6209 (2007)

Adaptive interferometry of protein on a BioCD

Leilei Peng, Manoj M. Varma, Wonryeon Cho, Fred E. Regnier, and David D. Nolte
Appl. Opt. 46(22) 5384-5395 (2007)

Molecular interferometric imaging

Ming Zhao, Xuefeng Wang, and David D. Nolte
Opt. Express 16(10) 7102-7118 (2008)

Spinning-disk self-referencing interferometry of antigen–antibody recognition

M. M. Varma, D. D. Nolte, H. D. Inerowicz, and F. E. Regnier
Opt. Lett. 29(9) 950-952 (2004)