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Issue 6, 2006
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Characterisation of spatial and temporal changes in pH gradients in microfluidic channels using optically trapped fluorescent sensors

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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.

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

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Publication details

The article was received on 06 Dec 2005, accepted on 24 Mar 2006 and first published on 12 Apr 2006


Article type: Paper
DOI: 10.1039/B517237C
Citation: Lab Chip, 2006,6, 788-793
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    Characterisation of spatial and temporal changes in pH gradients in microfluidic channels using optically trapped fluorescent sensors

    N. Klauke, P. Monaghan, G. Sinclair, M. Padgett and J. Cooper, Lab Chip, 2006, 6, 788
    DOI: 10.1039/B517237C

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