Development of a Low Cost Hemin based Dissolved Oxygen Sensor with Anti-Biofouling Coating for Water Monitoring

Conventional electrochemical dissolved oxygen (DO) sensors are expensive as they use Platinum in their construction. In addition, these sensors bio-foul when used in natural or wastewater, which leads to reduced sensitivity and variable performance. Here, we address these problems by i) replacing Platinum with Hemin as a low cost alternative for electrocatalysing the oxygen reduction reaction and ii) using silicone rubber (PDMS) functionalized with polyethyleneglycol (PEG) as the anti biofouling gas permeable membrane to provide selectivity with an increased lifetime. Our DO sensor has a sensitivity of ${\bf 20.7 (\mu {A}/{cm}^{2})/({mg}/{L})}$ over a DO concentration range of 7–2 mg/L. Also, the common interferences such as phosphate and nitrate show minor influence in DO detection. Furthermore, the PEG grafting PDMS membranes protects the sensor from biofouling for 20 days in accelerated bio-fouling condition, while the unfunctionalized sensor loses its sensitivity in less than one day.