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

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.

Edited by
Pietro VINCENZINI, John A. JANSEN, Kazuhiko ISHIHARA and Thomas J. WEBSTER
S. Scarmagnani, Z. Walsh, F. Benito-Lopez, M. Macka, B. Paull, D. Diamond, "Incorporation of Acrylate Based Spiropyran Monoliths in Micro-Fluidic Devices for Photo-Controlled Electroosmotic Flow", Advances in Science and Technology, Vol. 76, pp. 100-105, 2010
Online since
October 2010
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