The subject invention pertains to a method for the production of an array of molecules immobilised on a substrate, comprising the deposition of the molecules from a micropipette containing them, onto the substrate, in a liquid environment, wherein the distance of the micropipette from the substrate is controlled in response to the ion current in the liquid. This method is particularly suitable for the deposition of biological molecules. The subject invention also pertains to an array of biological molecules deposited on a substrate.