Analytical Sciences

Abstract − Analytical Sciences, 19(7), 1065 (2003).

Single Particle Confocal FluorescenceSpectroscopy in Microchannels: Dependence of Burst Width and Burst AreaDistributions on Particle Size and Flow Rate
Joshua B. EDEL and Andrew J. deMELLO 
Department of Chemistry, Imperial CollegeLondon, South Kensington, London, SW7 2AZ, U. K.
This article presents a non-invasive,optical technique for measuring particulate flow within microfluidicchannels. Confocal fluorescence detection is used to probe singlefluorescently labeled microspheres (200 - 930 nm diameter) passing througha focused laser beam at a variety of flow rates (100 - 1000 nL/min).Simple statistical methods are subsequently used to investigate theresulting fluorescence bursts and generate single-particle burst width andburst area distributions. Analysis of such distributions demonstrates thatthe average burst width and burst area decrease as particle size increases.In addition, both burst width and burst area (for a given particle size)are observed to decrease as volumetric flow rate is increased. Thedependence of such distributions on particle size is proposed as apotential route to sizing single particles and molecules in microfluidicsystems.