Size-dependent electro-osmosis in a microchannel with low-permittivity, salt-free media

Feng Ming Chang, Yi Wen Chang, Yu Jane Sheng, Heng Kwong Tsao

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Electro-osmosis is the preferred transport mechanism in microfluidic systems. The electro-osmotic mobility in an aqueous solution is essentially independent of the microchannel size. However, in low-permittivity solvents, the screening effect is absent and the mobility is found to grow with the capillary radius according to our analytical theory and electro-osmotic flow experiments. Our results show that regardless of low surface charge density, electro-osmosis always occurs for long enough microchannels. Therefore, electro-osmosis provides a method for determining extremely low surface charge density associated with low-permittivity media. The implication in the response time of electronic paper is given as well.

Original languageEnglish
Article number164101
JournalApplied Physics Letters
Issue number16
StatePublished - 18 Oct 2010


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