However, the oxygen reduction reaction, which occurs at cathodic potentials, is subject to interference from other species, particularly in a complex matrix like water. It can also complicate the electrochemical detection of other species due to it's large reaction potential window. To this end, electrochemical approaches therefore require an oxygen permeable membrane behind which, the electrodes and electrolyte are placed. The membrane acts to ensure that only oxygen reaches the electrode surface by blocking other ions. While this approach is less expensive than the optical method, issues arise when trying to miniaturise the sensor device due to the requirement for a membrane. Miniaturisation is important to facilitate portability, but also to minimise consumption of oxygen. Reduction of oxygen is a destructive process, as the oxygen is irreversibly reduced to water, therefore, larger electrodes may inadvertently deplete the DO concentration with consequent false negatives. However, complex fabrication methods are required for membrane integration at smaller length scales, and as a result much research focuses on improving these methods. [10] Elimination of the membrane would make miniaturisation of devices significantly easier, but also opens the potential for interferents, such as chlorine, adversely affecting DO detection. In this work, we propose a method to quantify DO using interdigitated electrode arrays (IDE) without the need of a membrane and eliminate common interferent effects. In this approach, hydrogen peroxide (H2O2), produced as an intermediate species in oxygen reduction, is used as an indicator of overall DO concentration. This pathway is shown by Eq. 2 and Eq. 3 ,