March 10, 1999

Re: Coloured or fluorescent liquids for microfluidics?

Many images of microfluidic devices are taken using fluorescein in water.
There are also fluorescent dyes which can be uncaged with a laser pulse to
create a line of activated fluorescent material which can then be imaged as it
flows through a device.  To visualize molecular transport (e.g.
electrophoresis or even just diffusion) correctly, you will need to label
molecules with mobility similar to those you expect to use in  the real
application.  This is important because a small molecule like fluorescein can
diffuse rapidly, decreasing sharpness and hiding problems like dead volumes by
simply diffusing out of them.  You can find many types of fluorescent dyes for
scientific work from Molecular Probes, Inc.:   www.molecularprobes.com

John West
Microcosm Technologies
CAD for Microfluidics
johnwest@memcad.com
www.memcad.com