A method of forming a MEMS device by encapsulating a MEMS element with a sacrificial layer portion deposited over a substrate arrangement, the portion defining a cavity for the MEMS element, forming at least one strip of a further sacrificial material extending outwardly from the portion, forming a cover layer portion over the sacrificial layer portion, the cover layer portion terminating on the at least one strip, removing the sacrificial layer portion and the at least one strip, the removal of the at least one strip defining at least one vent channel extending laterally underneath the cover layer portion and sealing the at least one vent channel. A device including such a packaged micro electro-mechanical structure.