Silicon nitride was then blanket deposited using plasma enhanced chemical vapour deposition across the whole wafer to act as an insulating layer. This insulating layer was used to prevent unwanted electrochemical interactions along the connection tracks. To allow electrolyte access to the ultramicroband electrodes, vias (windows) were opened in the insulating Si3N4 layer (above the sensor electrodes using photolithography and dry etching. Additional vias were opened over the counter and pseudo-reference electrodes as well as the periphery microSD contact pads. Each device contained three separate interdigitated electrode sensors which are separated by 1.88 mm. This separation was maintained to prevent cross talk, i.e., electrochemical reactions occurring at one sensor from interfering with a neighbouring sensor (when operating without the microfluidic component) and also to provide sufficient surface area between the electrodes to facilitate correct integration of the microfluidic channels to prevent leaking and cross talk. Following fabrication, the wafer was diced to produce 28 separate chip dice.