Patent ID: 8206994

Claim:
A method for treating drops in a microfluid circuit comprising at least one microchannel containing a first fluid and drops of at least a second fluid contained in the first fluid by focusing a laser beam on interfaces of said drops and of the first fluid, wherein said method comprises modifying the surface tensions of said fluids by adding appropriate surface-active products to those fluids, and in using the heat sensitivity of the surface tensions of said fluids resulting from the focusing of the laser beam on the interfaces to sort those drops or to fractionate them into nanodrops or to fuse them when they contain different fluids, the laser beam wavelength being selected to be absorbed by the second fluid contained in the drops or by the different fluids contained in the drops, respectively, the first fluid and the constitutive material of the microchannel being transparent to this wavelength, wherein in order to sort drops of the second fluid present in the first fluid, the laser beam is focused upstream from a Y-branch, the crest of which comprises a tip directed upstream, the focal point of the laser beam being located between the end of this tip and the wall of the microchannel opposite to the deviation direction of the drops.