Écoulements microfluidiques pilotés sans contact par une onde laser

Abstract : The thermocapillary (or Marangoni) effect is the mechanical result of an interfacial tension gradient induced by a temperature gradient on a fluid interface. This effect manifests itself by inducing (i) the migration of an immersed finite-size object (droplet, bubble), and (ii) a deflexion of the interface. Due to its interfacial nature, the Marangoni effect is particularly relevant at small length scales, especially in the context of two-phase microfluidics. This thesis aims at applying the thermocapillary effect locally induced by laser heating, in order to create some basic optofluidic actuators (valve, switch, sampler). A quantitative study of these actuators is presented. The laser-forced destabilization of a co-flowing microfluidic jet, leading to its breakup, is also investigated. This “optical toolbox” represents a non-contacting, and microfabricationfree approach for the production and handling of droplets in digital microfluidics. Moreover, to characterize these droplet over long times, thus considering statistically significant populations, a simple optoelectronic device has been developed for measuring the size and velocity of the droplets in real time.
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Dynamique des Fluides [physics.flu-dyn]. Université Sciences et Technologies - Bordeaux I, 2010. Français


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Submitted on : Thursday, November 4, 2010 - 11:53:17 AM
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Matthieu Robert de Saint Vincent. Écoulements microfluidiques pilotés sans contact par une onde laser. Dynamique des Fluides [physics.flu-dyn]. Université Sciences et Technologies - Bordeaux I, 2010. Français. <tel-00532632>

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