title: ac electroosmosis in rectangular microchannels.
abstract: Motivated by the growing interest in ac electroosmosis as a reliable no moving parts strategy to control fluid motion in microfluidic devices for biomedical applications, such as lab-on-a-chip, we study transient and steady-state electrokinetic phenomena (electroosmosis and streaming currents) in infinitely extended rectangular charged microchannels. With the aid of Fourier series and Laplace transforms we provide a general formal solution of the problem, which is used to study the time-dependent response to sudden ac applied voltage differences in case of finite electric double layer. The Debye-Huckel approximation has been adopted to allow for an algebraic solution of the Poisson-Boltzmann problem in Fourier space. We obtain the expressions of flow velocity profiles, flow rates, streaming currents, as well as expressions of the complex hydraulic and electrokinetic conductances. We analyze in detail the dependence of the electrokinetic conductance on the extension of linear dimensions relative to the Debye length, with an eye on finite electric double layer effects.
authors.affiliation: Center of Research in Microengineering (CRIM) Laboratory, Scuola Superiore Sant'Anna, Viale R. Piaggio 34, 56025 Pontedera (Pisa), Italy. campisi@crim.ssup.it
authors.forename: Michele
authors.initials: M
authors.lastname: Campisi
authors.forename: Dino
authors.initials: D
authors.lastname: Accoto
authors.forename: Paolo
authors.initials: P
authors.lastname: Dario
mesh_terms: D002627:Chemistry, Physical / Q000379:methods*; D004058:Diffusion; D004560:Electricity; D004563:Electrochemistry / Q000379:methods*; D007700:Kinetics; D046210:Microfluidic Analytical Techniques; D015233:Models, Statistical; D008962:Models, Theoretical; D009995:Osmosis; D011312:Pressure; D012984:Software