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Particle migration by optical scattering force in microfluidic system with light-absorbing liquid / Masahiro Motosuke in Journal of heat transfer, Vol. 134 N° 5 (Mai 2012) 

Public ISBD [article]  in Journal of heat transfer > Vol. 134 N° 5 (Mai 2012) . - 06 p. Titre : Particle migration by optical scattering force in microfluidic system with light-absorbing liquid Type de document : texte imprimé Auteurs : Masahiro Motosuke, Auteur ; Jun Shimakawa, Auteur ; Dai Akutsu, Auteur Année de publication : 2012 Article en page(s) : 06 p. Note générale : heat transfer Langues : Anglais (eng) Mots-clés : microfluidics;  optical  radiation  pressure;  optical  scttering  force;  particle  control;  viscosity;  photothermal  effect Index. décimale : 536 Chaleur. Thermodynamique Résumé : Optical force offers a promise of being applied as a noninvasive manipulation tool for microscopic objects without physical contact. Particle control in a microfluidic system is achieved by optics showing advantages over electric or the other methods. With optics, the fluid need not to be contamination free and there is no need for electrode fabrication. Particles can experience different forces depending on the optical configuration. The scattering force is predominant under parallel or gently focused irradiation, while the gradient force is predominant in tightly focused irradiation. This paper reports the experimental and theoretical investigations of the potential of optical scattering force for particle control technique in a microfluidic system with a light-absorbing liquid. The light-absorption of the incident laser beam in the liquid causes a temperature rise and induces the corresponding property changes of liquid and particles. The experiments were presented for particle migration using the scattering force exerted by a compact diode laser with a wavelength of 635 nm. The absorption of the light in the liquid was controlled by the concentration of dye substance added in a buffer solution. The velocities of polystyrene particles with a diameter of 1.9 µm and the temperature distributions of the liquid under laser irradiation were measured by tracking their movement and by temperature-sensitive fluorophore, respectively. When there is no light absorption in the liquid, the migration velocity of particles under the laser beam is linearly increased with the increase of the laser power, in agreement with the calculations based on ray optics theory. In the case of light-absorbing liquid, the migration speed of particles experiencing the optical force indicates a nonlinear increase as the laser power increases. This enhancement mainly attributes to the temperature-sensitive change of liquid viscosity resulting in a reduction of viscous drag for migrating particles. An appropriate arrangement of light absorption leads to an enhancement in the photophoretic velocity of particles, and eventual performance promotion of particle separation and/or sorting using the optical force. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO000134000005 [...] [article] Particle migration by optical scattering force in microfluidic system with light-absorbing liquid [texte imprimé] / Masahiro Motosuke, Auteur ; Jun Shimakawa, Auteur ; Dai Akutsu, Auteur . - 2012 . - 06 p. heat transfer Langues : Anglais (eng) in Journal of heat transfer > Vol. 134 N° 5 (Mai 2012) . - 06 p. Mots-clés : microfluidics;  optical  radiation  pressure;  optical  scttering  force;  particle  control;  viscosity;  photothermal  effect Index. décimale : 536 Chaleur. Thermodynamique Résumé : Optical force offers a promise of being applied as a noninvasive manipulation tool for microscopic objects without physical contact. Particle control in a microfluidic system is achieved by optics showing advantages over electric or the other methods. With optics, the fluid need not to be contamination free and there is no need for electrode fabrication. Particles can experience different forces depending on the optical configuration. The scattering force is predominant under parallel or gently focused irradiation, while the gradient force is predominant in tightly focused irradiation. This paper reports the experimental and theoretical investigations of the potential of optical scattering force for particle control technique in a microfluidic system with a light-absorbing liquid. The light-absorption of the incident laser beam in the liquid causes a temperature rise and induces the corresponding property changes of liquid and particles. The experiments were presented for particle migration using the scattering force exerted by a compact diode laser with a wavelength of 635 nm. The absorption of the light in the liquid was controlled by the concentration of dye substance added in a buffer solution. The velocities of polystyrene particles with a diameter of 1.9 µm and the temperature distributions of the liquid under laser irradiation were measured by tracking their movement and by temperature-sensitive fluorophore, respectively. When there is no light absorption in the liquid, the migration velocity of particles under the laser beam is linearly increased with the increase of the laser power, in agreement with the calculations based on ray optics theory. In the case of light-absorbing liquid, the migration speed of particles experiencing the optical force indicates a nonlinear increase as the laser power increases. This enhancement mainly attributes to the temperature-sensitive change of liquid viscosity resulting in a reduction of viscous drag for migrating particles. An appropriate arrangement of light absorption leads to an enhancement in the photophoretic velocity of particles, and eventual performance promotion of particle separation and/or sorting using the optical force. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO000134000005 [...]