A8_Microfluidics_fundamentals_II
.pdf
Nanofluidics – size and charge effects
Effect of the Debye length on electric potentials and ion populations. (a) when κa >> 1 bulk and micro/nanochannel ion concentrations are nearly identical. (b) Whem κa ≈ 1 the solution inside the nanochannel must become enriched in ions of one charge to maintain electroneutrality. (c) The electric potential rapidly decays to the bulk value when κa >> 1. (d) When κa ≈ 1 the electric potential can deviate from the bulk due to the influence of immobile surface charges. (e) The concentration of cations (orange) and anions (blue) when κa >> 1 equals the bulk concentration. (f) The concentration of counterions (orange) is enriched relative to coions (blue) when κa ≈ 1.
Class info
•HW4 – microfluidics– is available in the class homepage – due Sunday, October 13
•Required reading: make sure you read and understand the microfluidics support papers
•This week office hours: 10-12h on Thursday, October 10
•Next week: no formal classes. Visit to INESC MN clean room – please sign-up
•P1 papers expected to be available Sunday, October 13
•A9 and A10 – case studies in biomicrofluidics; target capture in microchannels