Trapping and manipulation of microparticles using laser-induced convection currents and photophoresis.
In this work we demonstrate optical trapping and manipulation of microparticles suspended in water due to laser-induced convection currents. Convection currents are generated due to laser light absorption in an hydrogenated amorphous silicon (a:Si-H) thin film. The particles are dragged towards the beam's center by the convection currents (Stokes drag force) allowing trapping with powers as low as 0.8 mW. However, for powers >3 mW trapped particles form a ring around the beam due to two competing forces: Stokes drag and thermo-photophoretic forces. Additionally, we show that dynamic beam shaping can be used to trap and manipulate multiple particles by photophotophoresis without the need of lithographically created resistive heaters.
Benemérita Universidad Autónoma de Puebla, Calle 4 Sur 104 Colonia Centro, Puebla, Puebla, 72000, Mexico.
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Flores-Flores
Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro No.1, Tonanzintla, Puebla, Mexico.
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Torres-Hurtado
Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro No.1, Tonanzintla, Puebla, Mexico.
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Páez
Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro No.1, Tonanzintla, Puebla, Mexico.
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Ruiz
Benemérita Universidad Autónoma de Puebla, Calle 4 Sur 104 Colonia Centro, Puebla, Puebla, 72000, Mexico.
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Beltrán-Pérez
University of Glasgow, James Watt South Building, Glasgow G12 8QQ, Scotland, UK.
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Neale
Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro No.1, Tonanzintla, Puebla, Mexico.
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Ramirez-San-Juan
Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro No.1, Tonanzintla, Puebla, Mexico.
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Ramos-García
(120.6810) Thermal effects; (140.3300) Laser beam shaping; (350.4855) Optical tweezers or optical manipulation