Microspheres and single molecule detection

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Principal investigator : Jerome Wenger

Complex optical instrumentation, and/or expensive nanofabrication can hinder the progress of photonic technologies. Here we demonstrate that dielectric microspheres offer a relevant cost-effective alternative to more advanced lenses and objectives.

Beating the diffraction barrier with microspheres

Commercially available microspheres under focused Gaussian illumination can achieve three-axis optical confinement below the diffraction limit, with an observation volume significantly lower than the wavelength cube. The concept has strong connections with solid immersion lenses, yet with a much simpler and cost-effective system. Microspheres open new opportunities for low-cost and highly parallel means to develop new microscopy techniques, with applications to biophotonics, plasmonics, and optical data storage.

Disposable objective lenses for single molecule FCS detection

Viable single molecule FCS experiments at concentrations 1-1000 nM with different objectives costing less than $40 are demonstrated. This offers a simple and low-cost alternative to the conventional complex microscope objectives.

Multi-focus FCS with photonic nanojets array

An array of latex microspheres replaces the complex microscope objective commonly used in fluorescence microscopy. This realizes a novel regime where several focal spots are illuminated to detect the possible presence of a fluorescent molecule in one of them. The system is an efficient disposable lens element that enables single molecule sensitivity at low picomolar concentration. The simplicity of the design makes it perfect for integration in portable microfluidic readers.


[11] P. Ghenuche, J. de Torres, P. Ferrand, J. Wenger, Multi-focus parallel detection of fluorescent molecules at picomolar concentration with photonic nanojets arrays, Appl. Phys. Lett. 105, 131102 (2014).
[10] 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).
[9] P. Ghenuche, H. Rigneault, J. Wenger, Photonic nanojet focusing for hollow-core photonic crystal fiber probes, Appl. Opt. 51, 8637-8640 (2012).
[8] H. Aouani, P. Schön, S. Brasselet, H. Rigneault, J. Wenger, Two-photon fluorescence correlation spectroscopy with high count rates and low background using dielectric microspheres, Biomed. Opt. Express 1, 1075-1083 (2010).
[7] J. Wenger, H. Rigneault, Photonic Methods to Enhance Fluorescence Correlation Spectroscopy and Single Molecule Fluorescence Detection, Int. J. Mol. Sci. 11, 206-221 (2010)
[6] 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).
[5] Gérard D., Devilez A., Aouani H., Stout B., Bonod N., Wenger J., Popov E., Rigneault H., Efficient excitation and collection of single molecule fluorescence close to a dielectric microsphere, J. Opt. Soc. Am. B 26, 1473-1478 (2009).
[4] Devilez A., Bonod N., Stout B., Gérard D., Wenger J., Rigneault H., Popov E., Three-dimensional subwavelength confinement of light with dielectric microspheres, Opt. Express 17, 2089-2094 (2009).
[3] Gérard D., Wenger J., Devilez A., Gachet D., Stout B., Bonod N., Popov E., Rigneault H., Strong electromagnetic confinement near dielectric microspheres to enhance single-molecule fluorescence, Opt. Express 16, 15297-15303 (2008).
[2] Wenger J., Gérard D., Aouani H., Rigneault H., Disposable Microscope Objective Lenses for Fluorescence Correlation Spectroscopy Using Latex Microspheres, Anal. Chem. 80, 6800-6804 (2008).
[1] Ferrand P., Wenger J., Devilez A., Pianta M., Stout B., Bonod N., Popov E., Rigneault H., Direct imaging of photonic nanojets, Opt. Express 16, 6930-6940 (2008).