(340c) Electro-Hydrodynamic Concentration of Neutrally Buoyant Particles in Microliter Droplets

Microdevices that are based upon manipulation of tiny fluid droplets carrying a biological or chemical content have recently emerged as a promising technology for a wide range of applications. Such devices also referred to as “digital microfluidics” do not require a network of microfabricated channels, valves, mixers, and pumps for moving fluids around on the chip. The open and scalable architecture of digital microfluidics plus readily available techniques for basic droplet operations (dispensing, transporting, splitting, merging) offer the possibility of fabricating simple, easily reconfigurable and low cost devices for large-scale parallel operation of liquid samples. The current focus of the droplet-based technology is on the development of methods to perform generic laboratory procedures inside a tiny droplet. We present a new method for the AC electric field driven concentration and removal of particles from droplets of aqueous polymer solutions. Experiments conducted on suspensions of blue polyethylene microspheres dispersed in a saliva simulant and suspensions of hollow glass particles dispersed in low volatile polyethylene glycol (PEG 200) demonstrated that the proposed electro-hydrodynamic method can operate over a broad range of electrical conductivity and viscosity of suspending fluids.

The work is supported by NASA grant NNX09AK06G