title: Nanoscale actuation of electrokinetic flows on thermoreversible surfaces.
abstract: We report on a novel approach for controlling nanohydrodynamic properties at the solid-liquid interfaces through the use of stimuli-responding polymer coatings. The end-tethered polymers undergo a phase separation upon external activation. The reversible change in the thickness and polarity of the grafted polymers yields in a dynamic control of the surface-generated, electrokinetic phenomena. Nonactivated, swollen polymers are thicker than the electrical double layer (EDL) and prohibit the development of an EOF even on charged surfaces. On the other hand, activated polymer chains shrink and become thinner than the EDL and allow for the EOF to build up unimpeded. We show here that, for given experimental conditions, the EOF velocity on the shrunken surface is 35 times greater than the one on the nonactivated surface. Furthermore, we reveal that coupling of such surfaces with dense arrays of thermal actuators developed in our laboratory can lead to novel micro- and nanofluidic devices.
authors.affiliation: LAAS-CNRS, University of Toulouse, Toulouse, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Paumier
authors.forename: Jan
authors.initials: J
authors.lastname: Sudor
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Gue
authors.forename: Françoise
authors.initials: F
authors.lastname: Vinet
authors.forename: Meng
authors.initials: M
authors.lastname: Li
authors.forename: Yves J
authors.initials: YJ
authors.lastname: Chabal
authors.forename: Alain
authors.initials: A
authors.lastname: Estève
authors.forename: Mehdi
authors.initials: M
authors.lastname: Djafari-Rouhani
mesh_terms: D000180:Acrylic Resins; D004563:Electrochemistry; D053841:Electroosmosis; D007700:Kinetics; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000180:Acrylic Resins; C052970:poly-N-isopropylacrylamide