The present invention relates to an apparatus and a method of fabricating the apparatus for dispensing a sample for subsequent analysis by mass spectrometry. The apparatus comprises a polymer substrate (1), in which a covered microchannel (3) has been etched, a wall of the microchannel comprising an electrically conductive material (2) for applying a voltage allowing the sample to be sprayed into a mass spectrometer from the open end (4) of the microchannel. The present application also discloses various applications of the apparatus.