The invention concerns an electrochemical cell which, either alone or together which a substrate onto which it is placed, is in the form of a receptacle. The electrochemical cell contains a working electrode and a counter electrode, the working electrode being in a wall of the receptacle. At least one of the electrodes has at least one dimension of less than 50µm. The electrochemical cell is principally intended for use as a micro−electrode suitable for screening water, blood, urine or other biological or non−biological fluids.
