Laser intracavity analysis of droplets by multicolour microfluidic dye laser

An original method based on a microfluidic dye laser has been investigated to carry out optical analysis of microfluidic droplets. Droplets that have been the subject of extensive works over the last five years appear as the best tool to manipulate subnanoliter volumes for a lot of applications in both chemistry and biology. We have designed a device that combines a microfluidic dye laser and a droplet generator on the same chip. Intracavity measurement can thus be performed as the droplets pass through the laser cavity. Depending on the droplet shape, whether it is spherical or not, the presence of the droplet inside the optical cavity results in an extinction of the laser signal or in a variation of its intensity. This innovative method can be used for in-situ direct analysis of any event occuring inside the droplet volume. In addition to this work, in order to develop a device allowing optical analysis over the full visible spectrum, we have also developed a new laser that is able to deliver multiple wavelength on-demands. Such improvement in the laser design has several advantages such as reducing the number of equipment around the set-up.