Peer-reviewed Publications |
Blandin, P., Druon, F., Balembois, E., Georges, P., Leveque-Fort, S., & Fontaine-Aupart, M. P. (2006). Diode-pumped passively mode-locked Nd : YVO4 laser at 914 nm. OPTICS LETTERS, 31(2), 214–216.
Résumé: Received July 22, 2005; revised September 12, 2005; accepted September 14, 2005 We demonstrate, for the first time, to our knowledge, a diode-pumped passively mode-locked Nd:YVO4 laser, operating on the F-4(3/2) I-_4(9/2) transition of the neodymium ion at 914 nm. We obtained 8.8 ps pulses at approximately 914 nm at a repetition rate of 94 MHz, and an averaged output power of 87 mW by using a semiconductor saturable absorber mirror. (c) 2006 Optical Society of America.
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Blandin, P., Druon, F., Balembois, F., Georges, P., Leveque-Fort, S., & Fontaine-Aupart, M. P. (2006). Impulsional Nd : YVO4 laser at 914 nm pumped by diode. JOURNAL DE PHYSIQUE IV, 135, 249–250.
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Deniset-Besseau, A., Leveque-Fort, S., Fontaine-Aupart, M. P., Roger, G., & Georges, P. (2007). Three-dimensional time-resolved fluorescence imaging by multifocal multiphoton microscopy for a photosensitizer study in living cells. APPLIED OPTICS, 46(33), 8045–8051.
Résumé: Two-photon fluorescence microscopy is widely applied to biology and medicine to study both the structure and dynamic processes in living cells. The main issue is the slow acquisition rate due to the point scanning approach limiting the multimodal detection (x, y, z, t). To extend the performances of this powerful technique, we present a time-resolved multifocal multiphoton microscope (MMM) based on laser amplitude splitting. An array of 8 X 8 foci is created on the sample that gives a direct insight of the fluorescence localization. Four-dimensional (4D) imaging is obtained by combining simultaneous foci scanning, time-gated detection, and z displacement. We illustrate time-resolved MMM capabilities for 4D imaging of a photosensitizer inside living colon cancer cells. The aim of this study is to have a better understanding of the photophysical processes implied in the photosensitizer reactivity. (C) 2007 Optical Society of America.
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Galas, J. C., Peroz, C., Kou, Q., & Chen, Y. (2006). Microfluidic dye laser intracavity absorption. APPLIED PHYSICS LETTERS, 89(22).
Résumé: The authors report absorption measurements on low concentration analytes using a microfluidic dye laser. The laser cavity is made of two gold mirrors coated on the end faces of two optical fibers inserted in a chip. Rhodamine 6G dye molecules dissolved in ethanol are used for laser amplification and absorption measurements are done with methylene blue dye solutions. When optically pumped with a frequency doubled Nd:YAG laser at 532 nm wavelength, the device shows a laser output emission at 565 nm and a high sensitivity of the lasing output to the losses in the cavity, in good agreement with the results of numerical calculations.
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Galas, J. C., Torres, J., Belotti, M., Kou, Q., & Chen, Y. (2005). Microfluidic tunable dye laser with integrated mixer and ring resonator. APPLIED PHYSICS LETTERS, 86(26).
Résumé: We report on results of design and fabrication of a microfluidic dye laser that consists of a ring resonator, a waveguide for laser emission output, and microfluidic elements for flow control, all integrated on a chip. The optical resonator and the waveguide were obtained by photolithography, whereas microfluidic elements such as channels, valves, and pumps were fabricated by multilayer soft lithography. As results, the prototype device worked with a few nanoliters of Rhodamine 6G dye molecules in ethanol solution and showed a laser threshold of similar to 15 μJ/mm(2) when optically pumped with a frequency doubled Nd:YAG laser at 532 nm wavelength. The modification of the laser output intensity due to photobleaching effect was characterized by changing the dye flow velocity through the cavity. In addition, the emission wavelength of the laser could be easily tuned by changing the dye molecule concentration with the integrated microfluidic elements. (c) American Institute of Physics.
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Kou, Q., Yesilyurt, I., & Chen, Y. (2006). Collinear dual-color laser emission from a microfluidic dye laser. APPLIED PHYSICS LETTERS, 88(9).
Résumé: Collinear dual-color laser emission on a chip is obtained from a liquid dye mixture flowing through an optical microcavity. Soft lithography has been used to fabricate the microfluidic channels and integrate the optical resonator. The laser cavity, of nanoliter volume, is made of two parallel gold mirrors coated on the end faces of optical fibers and integrated into a polydimethylsiloxane chip. Such a design allows a simple but efficient coupling of the laser emission with an optical fiber. The amplification medium is composed of rhodamine 6G and sulforhodamine, dissolved in a common ethanol solution. When the dye mixture is optically pumped by a pulsed and frequency-doubled Nd:YAG laser, simultaneous laser emission at wavelengths 559 nm and 597 nm is observed, showing yellow and red colors with a complete spatial overlap within the single output beam. Moreover, the overall laser efficiency for the dye mixture system is significantly increased compared to that for the individual dyes. (c) 2006 American Institute of Physics.
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Kou, Q., Yesilyurt, I., Studer, V., Belotti, M., Cambril, E., & Chen, Y. (2004). On-chip optical components and microfluidic systems. MICROELECTRONIC ENGINEERING, 73-4, 876–880.
Résumé: We present the concept and the fabrication of on-chip optical components based on new microfluidic functionalities. Soft lithography has been used for the fabrication of microfluidic devices made of poly-dimethylsiloxane (PDMS). By filling the microchannels with a liquid of high refractive index, waveguides can be obtained. Other types of microoptical components such as beamsplitters, couplers, lenses and prisms are also fabricated. By inserting optical fibres into the microchannels, optical measurements are performed to show the expected effects. In addition, the dynamic spectroscopic detection of micro-beads of different colours has been demonstrated, and this should be applicable in various chemical and biological applications. (C) 2004 Elsevier B.V. All rights reserved.
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Lacroix-Gueu, P., Briandet, R., Leveque-Fort, S., Bellon-Fontaine, M. N., & Fontaine-Aupart, M. P. (2005). In situ measurements of viral particles diffusion inside mucoid biofilms. COMPTES RENDUS BIOLOGIES, 328(12), 1065–1072.
Résumé: Fluorescence correlation spectroscopy (FCS) under two-photon excitation was used successfully to characterize the diffusion properties of model virus particles (bacteriophages) in bacterial biofilm of Stenotrophonas maltophilia. The results are compared to those obtained with fluorescent latex beads used as a reference. The FCS data clearly demonstrated the possibility for viral particles to penetrate inside the exopolymeric matrix of mucoid biofilms, and hence to benefit from its protective effect toward antimicrobials (antibiotics and biocides). Microbial biofilms should hence be considered as potential reservoirs of pathogenic viruses, and are probably responsible for numerous persistent viral infections.
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Le Moal, E., Fort, E., Leveque-Fort, S., Cordelieres, F. P., Fontaine-Aupart, M. - P., & Ricolleau, C. (2007). Enhanced fluorescence cell imaging with metal-coated slides. BIOPHYSICAL JOURNAL, 92(6), 2150–2161.
Résumé: Fluorescence labeling is the prevailing imaging technique in cell biology research. When they involve statistical investigations on a large number of cells, experimental studies require both low magnification to get a reliable statistical population and high contrast to achieve accurate diagnosis on the nature of the cells' perturbation. Because microscope objectives of low magnification generally yield low collection efficiency, such studies are limited by the fluorescence signal weakness. To overcome this technological bottleneck, we proposed a new method based on metal-coated substrates that enhance the fluorescence process and improve collection efficiency in epifluorescence observation and that can be directly used with a common microscope setup. We developed a model based on the dipole approximation with the aim of simulating the optical behavior of a fluorophore on such a substrate and revealing the different mechanisms responsible for fluorescence enhancement. The presence of a reflective surface modifies both excitation and emission processes and additionally reshapes fluorescence emission lobes. From both theoretical and experimental results, we found the fluorescence signal emitted by a molecular cyanine 3 dye layer to be amplified by a factor similar to 30 when fluorophores are separated by a proper distance from the substrate. We then adapted our model to the case of homogeneously stained micrometer-sized objects and demonstrated mean signal amplification by a factor similar to 4. Finally, we applied our method to fluorescence imaging of dog kidney cells and verified experimentally the simulated results.
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Le Moal, E., Fort, E., Leveque-Fort, S., Janin, A., Murata, H., Cordelieres, F. P., Fontaine-Aupart, M. - P., & Ricolleau, C. (2007). Mirror slides for high-sensitivity cell and tissue fluorescence imaging. JOURNAL OF BIOMEDICAL OPTICS, 12(2).
Résumé: Fluorescence microscopy has become the method of choice in the majority of life-science applications. We describe development and use of mirror slides to significantly enhance the fluorescence signal using standard air microscope objectives. This technique offers sufficient gain to achieve high-sensitivity imaging, together with wide field of observation and large depth of focus, two major breakthroughs for routine analysis and high-throughput screening applications on cells and tissue samples. (C) 2007 Society of Photo-Optical Instrumentation Engineers.
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Luo, C., Li, H., Xiong, C., Peng, X., Kou, Q., Chen, Y., Ji, H., & Ouyang, Q. (2007). The combination of optical tweezers and microwell array for cells physical manipulation and localization in microfluidic device. BIOMEDICAL MICRODEVICES, 9(4), 573–578.
Résumé: A microfluidic device combined with the microwell array and optical tweezers was set up for cell manipulation, localization and cultivation. Yeast cells were manipulated by a 1,064 nm laser and transferred to microwell array as a demonstration. The flow velocities at which the yeast cell can be confined in microwells of different sizes are charactered. The simulation of the cell's flow trace in the microwell at different flow velocities is consisting with our experiment result. And we also proved a trapping laser power of 0.30 W is harmless for yeast cell cultivation. As a simple approach, this method can push forward the cell cultivation, cell interaction and other cell biology or biomedical studies in microfluidic system.
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Steenkeste, K., Lecart, S., Deniset, A., Pernot, P., Eschwege, P., Ferlicot, S., Leveque-Fort, S., Briandet, R., & Fontaine-Aupart, M. - P. (2007). Ex vivo fluorescence imaging of normal and malignant urothelial cells to enhance early diagnosis. PHOTOCHEMISTRY AND PHOTOBIOLOGY, 83(5), 1157–1166.
Résumé: Urinary cytology is a noninvasive and unconstraining technique for urothelial cancer diagnosis but lacks sensitivity for detecting low-grade lesions. In this study, the fluorescence properties of classical Papanicolaou-stained urothelial cytological slides from patients or from cell lines were monitored to investigate metabolic changes in normal and tumoral cells. Time- and spectrally-resolved fluorescence imaging was performed at the single cell level to assess the spectral and temporal properties as well as the spatial distribution of the fluorescence emitted by urothelial cells. The results reveal quite different fluorescence distributions between tumoral urothelial cells, characterized by a perimembrane fluorescence localization, and the normal cells which exhibit an intracellular fluorescence. This is not caused by differences in the fluorescence emission of the endogenous fluorophores NAD(P)H, flavoproteins or porphyrins but by various localization of the EA 50 Papanicolaou stain as revealed by both the spectral and time-resolved parameters. The present results demonstrate that the use of single-cell endofluorescence emission of Papanicolaou-stained urothelial cytological slides can allow an early ex vivo diagnosis of low-grade bladder cancers.
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Actes de Conférences |
Kou, Q., Yesilyurt, I., Escalier, G., Galas, J. C., Coureau, L., & Chen, Y. (2004). Microfluidic dye laser integration in a lab-on-a-chip device. In MEMS/MOEMS TECHNOLOGIES AND APPLICATIONS II (Vol. 5641, pp. 112–115).
Résumé: We report on an original design and fabrication of microfluidic dye laser integrated into a functional polydimethylsiloxane (PDMS) lab-on-a-chip system. Soft lithography has been used for the fabrication of the microfluidic channels allowing the liquid dye circulation. The laser cavity, formed by two cleaved optical fibers with end face metallization, is directly integrated into a microfluidic channel. The active dye molecules are optically pumped by a pulsed and frequency-doubled Nd:Yag laser at 532 nm wavelength. Finally, the output laser beam is extracted and coupled into the optical fiber. As a result, the characteristics of the laser output power as a function of pumping energy density is presented. We also show that the micro dye laser we fabricated can work steadily with an average output power up to 0.35 mW. The wavelength tunability is also demonstrated with the laser system.
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