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Single Molecule FCS fiber endoscope

Intensity is not enough

Single molecule methods provide access to a wide variety of data such as local concentration, structure or mobility of molecules. However, single molecule detection is a challenging task, and requires complex microscope apparatus.

A portable endoscope to observe single molecules : the smallest FCS setup ever

We have reached single molecule sensitivity with fluorescence detection using a modified optical fiber probe. The original system contains a glass microbead at the end of the optical fiber which works as a tiny lens to focus light. The fiber-microbead ensemble is also used to collect the low amount of light emitted by the individual molecules. That way, the bulky microscope is replaced by a remote fiber sensor connected to a miniaturized USB-connected device. This patented technique opens biomedicine and environment monitoring to single molecule analysis.

Hollow-core photonic crystal fiber probe for single molecule endoscopy

Current optical fiber probes struggle with large luminescence background. We use A hollow-core photonic crystal fiber (HC-PCF) probe solves this challenge. Compared to earlier work with silica fibers, the new HC-PCF-microsphere probe achieves a 200x improvement of the signal-to-noise ratio for a single molecule detection event, and a 1000x reduction of the minimum detectable concentration. The new device provides similar performance as conventional confocal microscopes.

Reference

  • P. Ghenuche, H. Rigneault, J. Wenger, Hollow-core photonic crystal fiber probe for remote fluorescence sensing with single molecule sensitivity, Opt. Express 20, 28379-28387 (2012).
  • H. Aouani, F. Deiss, J. Wenger, P. Ferrand, N. Sojic, H. Rigneault, "Optical-fiber-microsphere for remote fluorescence correlation spectroscopy", Opt. Express 17, 18912-18919 (2009) - PDF