Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10378314 | Journal of Colloid and Interface Science | 2005 | 11 Pages |
Abstract
Separation of colloidal particles of different sizes is becoming increasingly important due to rapid developments in the area of proteomics, genetic engineering, drug discovery, etc. In particular, there is a need to accomplish these separations on a microscale in 'lab-on-a-chip' devices. In this paper, we propose a new method for accomplishing separation of charged colloids of different sizes in a microchannel. This method involves a combination of pulses of lateral electric fields and Poiseuille flow in the axial direction. We develop a model for this separation technique and obtain closed form solutions for the mean velocity and the dispersion coefficient for a pulse of molecules introduced into the channel. These expressions are then utilized to determine the channel length and the separation time. For reasonable value of design constants, the proposed technique can separate molecules of different sizes that have diffusivities of 10â10 and 0.5Ã10â10Â m2/s in 15.7 s in a 3.7 mm long channel. The length and the time increase to 5.45 cm and 231 s if the ratio of the diffusivities is reduced from 2 to 1.2, i.e., the latter diffusivity is increased to 0.835Ã10â10Â m2/s, while keeping all the other parameters the same. If the diffusivities are about 10â9Â m2/s, the length and the time for separation are 1 cm and 17.5 s for D1/D2=2, and 16 cm and 269 s for D1/D2=1.2.
Keywords
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Colloid and Surface Chemistry
Authors
Zhi Chen, Anuj Chauhan,