Complex samples (e.g., cell extract) often require extensive cleanup or pretreatment before introduction to analysis channels in a miniaturized device. These pretreatment steps are often performed off-chip using large volumes of sample and other reagents, and hence often add substantially to the total analysis time and cost.

Dialysis, or size-based separation of species via selective diffusion through a semipermeable membrane, is a widely used technique for cleanup of biological samples. We have developed a technique for fabricating thin (4-14 micron) porous polymer dialysis membranes within the channels of a glass microchip. UV laser-initiated polymerization is used for controlled placement of the dialysis membrane in a chip for cleanup of complex or dirty samples; this technique is rapid and inexpensive and increases the potential functionality of integrated microfluidic devices. The semipermeable membrane and fabrication technique shows the potential for extracting a small molecular weight analyte of interest from a complex matrix.

References

S. Song, A.K. Singh, B.J. Kirby
"Electrophoretic Concentration of Proteins at Laser-Patterned Porous Membranes," submitted.

S. Song, A.K. Singh, T.J. Shepodd, B.J. Kirby "In-situ fabrication of Nanoporous Polymer Membranes for Microdialysis of Proteins," Analytical Chemistry, accepted.

B.J. Kirby, A.K. Singh
" In-situ fabrication of dialysis membranes in glass microchannels using laser-induced phase-separation polymerization," MicroTAS 2002, p.742-744, 2002.