Innovative system for deploying novel biosensors for water contaminant monitoring

The ability to remotely sense contaminants in surface and sub-surface waters can offer a deeper understanding of environmental conditions and an early warning system that will improve the efficiency of response to contaminant transport. The aim of this thesis was to develop an innovative system for field deployment of biosensors to facilitate environmental water quality monitoring. Two strands of work were addressed in developing themonitoring system (i) a flow cell in which to deploy the biosensor and (ii) integration of a uranyl ion (UO₂²⁺) biosensor.
Three different flow cell designs were investigated using both a finite element computational model and a flow-fluorescence experimental technique. These comprised a flow channel featuring an expanded central region to accommodate the sensor, but the rates of channel expansion were varied between each design. A reduction in flow cell efficiency with increasing flow rate for all three cell designs was linked to the development of regions of flow recirculation (eddies). However, the most gradually expanding flow channel restricted eddy development to higher flow rates in comparison to the other designs. This more efficient design, and an optimised operational protocol, was thus identified as a recommended method of biosensor deployment.
A biosensor for the detection of aqueous uranyl ions (UO₂²⁺) was developed from a sensor element created by Conroy (2012). Two different integration methods, screen-printed electrodes and solid gold electrodes for biosensor construction, were investigated. The biosensor response was linked to electrode nano-surface topography and electrode chemical composition, and was observed to be higher for the solid gold electrodes. The operational dynamic range of the integrated biosensor was improved by four orders of magnitude in comparison to the original laboratory proof of concept investigations for the sensor. Furthermore, recommendations for operational protocols were developed with respect to optimisation of integrated biosensor operation within a remotely controlled and automated water monitoring system.