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Thermo & Photopheresis of Molecules: Molecular Motion in Fluids

Thermophoresis is a known phenomenon refers to migration of particles along temperature gradients. It is also known as thermal diffusion or Soret effect in the literature. This phenomenon is being employed specially in the pharma industry to analyse the interaction and binding of nano-scaled molecules and particles with i.e., solvent or ions. In addition to biotechnological applications, natural thermophoresis could contribute to molecular evolution as observed in pores of near hot spring rocks on the ocean floor.

Mass transport due to the thermal gradient is described by a thermal diffusion term and diffusive back flow. The thermophoretic molecule drift velocity for dilute concentrations linearly depends on the temperature gradient.

Usually particles/molecules have a positive Soret coefficient leading to depletion in the hot area. However, for some rare cases, such as pullulan, deposition happens in the hot spots. In University of Exeter, we optically manipulate the temperature of solutions. Labelled particles or molecules are monitored by a probe beam exciting the fluorophore and collecting the emission.


Scope and Objectives:

We are interested in applying this technique on microsensors in order to

  • manipulate the concentration of particles and molecules

  • investigate the binding events of two species on the surface of the sensor