Characterisation of spatial and temporal changes in pH gradients in microfluidic channels using optically trapped fluorescent sensors

Klauke, N., Monaghan, P., Sinclair, G., Padgett, M. and Cooper, J. (2006) Characterisation of spatial and temporal changes in pH gradients in microfluidic channels using optically trapped fluorescent sensors. Lab on a Chip, 6, pp. 788-793. (doi:10.1039/b517237c)

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Abstract

This paper demonstrates the use of micron sized beads, modified with fluorescent dyes, as non-invasive sensors to probe the local changes in pH, within a microfluidic channel. To achieve this, amine modified polystyrene spheres (either 3 µm or 6 µm in diameter) were functionalised with the pH sensitive fluorochrome SNARF-1 to produce point sensors. The modified beads were trapped at defined positions close to a pair of integrated planar gold microelectrodes within the channel, using optical tweezers. Both transient and steady-state electrochemical potentials were applied to the microelectrode pair in order to generate changes in the local pH, associated with electrolysis. The functionalised beads indicated the pH changes in the channel, measured as a change in the fluorescence signal, generated by the immobilised pH sensitive dye. Responses were measured with temporal resolutions of between 1 and 200 ms, whilst the spatial resolution of the pH gradients was limited by the size of the beads to 3 μm.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Klauke, Dr Norbert and Padgett, Professor Miles and Cooper, Professor Jonathan and Monaghan, Dr Paul
Authors: Klauke, N., Monaghan, P., Sinclair, G., Padgett, M., and Cooper, J.
College/School:College of Science and Engineering > School of Engineering > Biomedical Engineering
College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
Journal Name:Lab on a Chip
Publisher:Royal Society of Chemistry
ISSN:1473-0197
ISSN (Online):1473-0189
Published Online:12 April 2006

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
362881Micro-fluidic analytical systems driven and interrogated with holographic opticsMiles PadgettEngineering & Physical Sciences Research Council (EPSRC)GR/S73006/01Physics and Astronomy