Sur ce site

Sur le Web du CNRS

Accueil du site > Séminaires > Année en cours > Thomas Bickel

Light-driven actuation of artificial micro-swimmers

Thomas Bickel

à 11h en salle C. Brot

Light is a convenient way to remotely control the motion of colloidal particles in a viscous environment. Conventional methods such as optical tweezers rely on optical forces to actuate the particles. Still, the design of artificial swimmers that propel themselves in the absence of force is a challenging issue. In this talk, I will present two realizations of active colloids.

First, the thermophoretic motion of metal-capped Janus colloids under laser illumination is discussed. Heat absorption by the metal cap generates a temperature gradient which in turn gives rise to a flow in the surrounding fluid, and thus causes self-propulsion. Collective phenomena resulting from phoretic interactions are also addressed.

Next, I will consider the transport of a particle adsorbed at the water-air interface and heated up by a laser. A few milliwatts of laser power is sufficient for the particle to escape the on-axis configuration and perform circular orbits at a speed greater than 100 micrometer/second. The motion of the particle results from thermocapillary flow it has itself created. Instabilities of the thermocapillary flow will be discussed.