Dielectrophoretic separation/isolation of rare particles/cell types form a heterogeneous suspension within a microfluidic system.

The isolation of fetal cells from maternal peripheral blood has long been proposed as a method for prenatal diagnosis but with only limited success. Current methods using antibody based separation strategies have proven unreliable. Here we describe a microfluidic system which can isolate specific cell types from a heterogeneous population, dependant upon their dielectric properties. A microfluidic separation chamber was fabricated using SU-8 photopolymer on glass with a glass lid bonded using UV-curable glue. Interdigitated microelectrodes were patterned onto the glass using photolithography and wet etching. When the electrodes are energized, the non-uniform AC electric fields produced result in a dielectrophoretic force acting differentially on the various cell types within the separation chamber. Computer aided modelling was used to optimise the fluidics (STAR-CD, Computational Dynamics Ltd.) of the device. Simulation of the forces present in the device due to the electric fields was achieved with the use of the Ansoft(R) Maxwell 2D field simulator, this allowed the optimisation of the electrode geometries. The whole system was then modelled prior to fabrication using the MATLAB programming language.