Tunable membranes for free-flow zone electrophoresis in PDMS microchip using guided self-assembly of silica microbeads

Yong Ak Song, Lidan Wu, Steven R. Tannenbaum, John S. Wishnok, Jongyoon Han

Research output: Contribution to journalArticle


In this paper, we evaluate the strategy of using self-assembled microbeads to build a robust and tunable membrane for free-flow zone electrophoresis in a PDMS microfluidic chip. To fabricate a porous membrane as a salt bridge for free-flow zone electrophoresis, we used silica or polystyrene microbeads between 3-6 μm in diameter and packed them inside a microchannel. After complete evaporation, we infiltrated the porous microbead structure with a positively or negatively charged hydrogel to modify its surface charge polarity. Using this device, we demonstrated binary sorting (separation of positive and negative species at a given pH) of peptides and dyes in standard buffer systems without using sheath flows. The sample loss during sorting could be minimized by using ion selectivity of hydrogel-infiltrated microbead membranes. Our fabrication method enables building a robust membrane for pressure-driven free-flow zone electrophoresis with tunable pore size as well as surface charge polarity.

Original languageEnglish (US)
Pages (from-to)11695-11699
Number of pages5
JournalAnalytical chemistry
Issue number24
StatePublished - Dec 17 2013


ASJC Scopus subject areas

  • Analytical Chemistry

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