A microstructure for transferring a substance through the surface of the skin, comprising a substrate having a first and a second side and at least one microstructure projecting from the second side of the substrate. The micrstructure has at least one hollow. The hollow is isolated from the fluid connection with the first side of the substrate. The hollow is configured such that, when the microstructure is inserted through the surface of the skin, at least part of the substance is transferred through the surface of the skin in the hollow.
