Abstract: A device for generating fluid micro streams comprises a body portion with a fluid supply cavity therein and a plurality of fluid micro channels interconnecting the fluid supply cavity with an external outlet face of the body portion, the body portion being formed from a plurality of stacked plates, said micro channels being formed at interfaces of at least certain of said stacked plates. The micro channels have an oblong cross-sectional profile over a certain section leading to the outlet face, with a major width that is greater than two times a minor width thereof, where the minor width is less than 200 um. The device can be used in apparatus for freezing of food, cooling a gas or inducing a chemical reaction between a liquid and a gas.