Reverse of Mixing Process with a Two-Dimensional Electro-Fluid-Dynamic Device.

Mixing of two solns. into one is a spontaneous process with a net increase in entropy. However, the reverse of the mixing process is usually not possible unless certain conditions are met. A continuous soln. stream contg. a mixt. of two compds. can be sepd. into two channels, each contg. a pure compd., thus reversing the mixing process using a two-dimensional microfluidic electro-fluid-dynamic (EFD) device. When the elec. field is strategically applied in the interconnecting channels of an EFD device, the pressure required to direct an analyte into a certain channel can be calcd. by using the solns. of elec. field and fluid dynamics in the mass balance equation. If the pressure and elec. potential at various inlets and outlets satisfy these predetd. conditions, the reverse of a mixing process is obsd. Conventional microfluidic devices were used to introduce samples from interconnecting channels or efficiently mix different solns. into a single channel. The EFD devices expand the spatial sepn. of analytes from one dimension to two using both the differential migration behavior of analytes and the velocity field distribution in different channel geometries. The devices designed according to these basic physicochem. principles can be used for complete processing of minute samples and to obtain pure chem. species from complex mixts. [on SciFinder(R)]