Microfluidic dye laser chip for intra-cavity absorption measurements

Among many others, absorbance measurement is one of the most useful techniques to determine sample concentration on a microfluidic chip. The main drawback of this technique comes from the limited optical path length that can be achieved on a chip. We propose here an original design of a microfluidic dye laser to perform intracavity absorption measurements. The effective optical path length and so the sensitivity are enhanced by a factor of about 15 in comparison with single pass measurement. In addition, the nanoliter active sample volume we used is six orders of magnitude less in comparison with common milliliter cuvette. Simple calculations that emphasize the potential utility of the method are also presented