Abstract: The present invention relates to an apparatus for detecting one or more analytes, for example analytes selected from the group comprising nucleic acids, metabolites, peptides, proteins, hormones, pesticides, neurotransmitters, ions in blood, electrolytes, toxic gases, pH and biological warfare agents, the apparatus comprising an insulating substrate, at least one first electrode on the substrate at least one elongate nanostructure extending from and electrically connected to the or each said electrode and extending over the surface of the wafer away from the respective electrode, a passivating layer covering the or each electrode, but not all of said at least one elongate nanostructure, a well crossing the at least one elongate nanostructure extending from the or each electrode and forming a static reservoir for a liquid being investigated for the presence of at least one analyte, a reference electrode provided on said substrate within said well or insertable into said well and respective readout pads electri