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Journal of Biomedical Optics • Open Access

Ultracompact alignment-free single molecule fluorescence device with a foldable light path
Author(s): Niraj Kumar Singh; Jenu V. Chacko; Suman Nag; Sudipta Maiti; Varun K. A. Sreenivasan

Paper Abstract

Instruments with single-molecule level detection capabilities can potentially benefit a wide variety of fields, including medical diagnostics. However, the size, cost, and complexity of such devices have prevented their widespread use outside sophisticated research laboratories. Fiber-only devices have recently been suggested as smaller and simpler alternatives, but thus far, they have lacked the resolution and sensitivity of a full-fledged system, and accurate alignment remains a critical requirement. Here we show that through-space reciprocal optical coupling between a fiber and a microscope objective, combined with wavelength division multiplexing in optical fibers, allows a drastic reduction of the size and complexity of such an instrument while retaining its resolution. We demonstrate a 4×4×18 cm3 sized fluorescence correlation spectrometer, which requires no alignment, can analyze kinetics at the single-molecule level, and has an optical resolution similar to that of much larger microscope based devices. The sensitivity can also be similar in principle, though in practice it is limited by the large background fluorescence of the commonly available optical fibers. We propose this as a portable and field deployable single molecule device with practical diagnostic applications.

Paper Details

Date Published: 1 February 2011
PDF: 4 pages
J. Biomed. Opt. 16(2) 025004 doi: 10.1117/1.3548311
Published in: Journal of Biomedical Optics Volume 16, Issue 2
Show Author Affiliations
Niraj Kumar Singh, Tata Institute of Fundamental Research (India)
Jenu V. Chacko, Tata Institute of Fundamental Research (India)
Suman Nag, Tata Institute of Fundamental Research (India)
Sudipta Maiti, Tata Institute of Fundamental Research (India)
Varun K. A. Sreenivasan, Macquarie Univ. (Australia)

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