ZnO based Screen Printed Aqueous Ammonia Sensor for Water Quality Monitoring

This paper presents a ZnO thick-film based sensor for liquid ammonia detection. The interdigitated electrode sensor was tested over a 0-10.9 mM ammonium ion range (i.e. covering the maximum value of ammonium as per European Union's regulations for drinking water directives (maximum of 0.027 mM) and the freshwater quality criteria for aquatic life by the US Environmental Protection Agency (maximum of 0.28 mM of total ammonia nitrogen (TAN) for chronic criteria and 1 mM of TAN for acute criteria). The sensor was characterized by using cyclic voltammetry and electrochemical impedance spectroscopy and showed excellent sensitivity (46.7 μAmM
^-1
cm
^-2
). The morphology of the thick film, analyzed by scanning electron microscope and X-ray diffraction, showed a highly crystalline structure with nanorectangles ranging from 60-200 nm.