Patent EP-2574401-A1 (EP)
Inventor: BAROUD CHARLES
IPC: B01L3/00
Filed: 2007-05-16
Abstract: The process for treating drops in a microfluidic circuit having a microchannel (12) containing a first fluid, comprises sorting drops (60, 64) of a second fluid contained in the first fluid, separating the drops into nanodrops, mixing the drops by focusing a laser beam (26) on an interface of the drops and the first fluid or the interface of each drop when the drops contain different fluids, modifying a surface tension of the fluids by adding suitable surfactant products to the fluids, and depositing an absorbent material on a microchannel surface. The process for treating drops in a microfluidic circuit having a microchannel (12) containing a first fluid, comprises sorting drops (60, 64) of a second fluid contained in the first fluid, separating the drops into nanodrops, mixing the drops by focusing a laser beam (26) on an interface of the drops and the first fluid or the interface of each drop when the drops contain different fluids, modifying a surface tension of the fluids by adding suitable surfactant products to the fluids, depositing an absorbent material on a microchannel surface, directing the laser beam on crossing point of drops to be sorted, blocking a transformation of the drops in the microchannel by focusing the laser beam on the lowerside interface of the drops, transforming the fluid until an arrival of another drop containing a fluid (F1), which is different from the first drop, then focusing the laser beam on the interface of two drops, changing the drop size to be mixed to change the quantities of reagents mixed during the mixing of drops, and monitoring fluid reaction in the mixed drops by continuously or discontinuously observing the drops using a microscope on a path traveled by the drops in the microfluidic circuit. A wavelength of the laser beam is chosen to be absorbed by the second fluid contained in the drops or by the different fluids contained in the drops. The first fluid and a constitutive material of microchannel are transparent in the wavelength. The laser beam is focused on an origin of a branch of Y of which a tip comprises a point oriented towards the origin of the branch. A focal point of the laser beam is located between an end of the point of branch and a microchannel wall, which is opposite to a direction of drop deviation. The sorting of drops of different fluids in the first fluid according to a sensitivity of the surface tension of the different fluids in heat is carried out by adjusting an energy transmitted to drop interfaces by the laser beam. The step of separating the drops into nanodrops comprises immobilizing the drops by focusing the laser beam on its lowerside interface in an another fluid flow (F2) containing the surfactant product, and separating the nanodrops from the drops using the fluid flow. The drop to be separated is transferred in the microchannel by the fluid flow containing the surfactant product. The focal point of laser beam is arranged in an immediate vicinity of a junction of the microchannel and an another microchannel in which nano-drops are diverted. The step of mixing comprises contacting the drops with each other in an another fluid flow (F3), then focusing the laser beam on the interface of drops. The fluids contained in the drops react with each other and form microreactors, where the reaction is initiated by the laser beam focused on the drops.