The lev-vection particle concentrator: some operational characteristics

Abstract

One or more thermal convection patterns can be produced in a body of liquid by maintaining a temperature differential between base and top (Rayleigh-Benard or Benard-Marangoni convection). An electric field applied across an array of interdigitated electrodes on the base can supply the necessary heat, assuming the liquid to be lossy. At the same time, the field can cause levitation of weakly-polarizable, non-buoyant particles, which tend to become entrained in the convective pattern: the effect has been termed lev-vection. In the simplest case of a slow, single, toroidal convection pattern, the particles become concentrated and trapped in a particular and repeatable region just above the electrode plane. A desire to scale-up the apparatus has led us to examine the effects of varying the various parameters (size, voltage, viscosity etc.) on the speed and stability of the induced circulation.