Electrokinetic micromixing of charged and non-charged samples near nano–microchannel junction

A nano–microchannel flow mixer comprising a polydimethylsiloxane (PDMS) microchannel and a Nafion nanoporous membrane is fabricated. It is shown that when an electric field is applied across the device, an ion enrichment/ion depletion effect occurs near the nano–microchannel junction. The mixing performance of the proposed device is examined for three different samples, namely fluorescein (negatively charged), Rhodamine 6G (positively charged), and Rhodamine B (electroneutral). It is shown that a mixing effect is obtained only for the Rhodamine B solution. Thus, it is inferred that nano–microchannel devices such as that presented in this study and those presented in the literature are unsuitable for biomolecule detection applications since such molecules are generally charged.

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