Paper Title:

Incorporation of Acrylate Based Spiropyran Monoliths in Micro-Fluidic Devices for Photo-Controlled Electroosmotic Flow

Periodical Advances in Science and Technology (Volume 76)
Main Theme 5th FORUM ON NEW MATERIALS PART E
Edited by Pietro VINCENZINI, John A. JANSEN, Kazuhiko ISHIHARA and Thomas J. WEBSTER
Pages 100-105
DOI 10.4028/www.scientific.net/AST.76.100
Citation Silvia Scarmagnani et al., 2010, Advances in Science and Technology, 76, 100
Online since October 2010
Authors Silvia Scarmagnani, Zarah Walsh, Fernando Benito-Lopez, Mirek Macka, Brett Paull, Dermot Diamond
Keywords Electroosmotic Pump, Monolith, Photoswitching, Spiropyran
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Spiropyran photochromic compounds can be switched using light exposure between a non-polar spiro form (SP) and a zwitterionic merocyanine form (MC) that is subject to protonation (MC-H+). It has recently been demonstrated by Walsh et al. that, under acidic conditions, electroosmotic flow (EOF) generated in vinyl based spiropyran monoliths can be modulated using light irradiation [1]. In this paper, we report a spiropyran-modified acrylate based monolith which is particularly sensitive to protonation in the MC form, producing a positively charged surface that converts to the unpolar SP form by exposure to white light. When the MC-H+ form is dominant, it produces a charged surface which enables a relatively high flow rate (up to 1.6 μl/min) to be generated under electroosmotic conditions. Upon exposure to white light, the concentration of MC-H+ decreases due to the photo-conversion to the uncharged SP form, with up to 20% reduction of the EOF. The process is reversible, and removal of the light source results in a flow increase back to the original rate. The ability to alter flow rates in micro-fluidic channels using light has very significant implications, as it could dramatically simplify the manner in which micro-flow systems are controlled.