Microfluidic Impedance Biosensor for the Detection of E. coli in Waterways

The current state of water pollution monitoring leaves much to be desired. With outdated and inadequate monitoring regimes and techniques meaning that a true understanding of the level of pollution in waterways is incomplete. The monitoring of faecal matter in waterways is achieved by detecting the quantity of faecal indicator organisms, specifically E. coli and intestinal enterococci. Due to the high cost associated with current sample testing method, the intensity and frequency of faecal matter contamination monitoring is limited.
The implementation of microfluidic biosensing devices has significant potential to increase the frequency of monitoring, provide rapid analysis, and reduce cost. This PhD aims to investigate the development of a cost effective microfluidic impedimetric immuno-biosensor for the real time detection of E. coli in waterway samples. Whilst addressing key issues for the implementation of biosensing devices, such as stability and reproducibility. Focusing on achieving sensitivity, selectivity, and limit of detection that are comparable to those achieved by current monitoring techniques but with a much shorter detection time.
The first stage of research will focus on developing an immunosensor, by immobilising E. coli antibodies covalently onto an electrode surface. This provides biorecognition sites for the target bacteria which when combined with impedance spectroscopy analysis techniques allows for detection of biorecognition events via the electrical response of the system. The second stage will investigate optimising the electrode design. The various electrode parameters, such as material, size and layout can have a significant impact on the sensing capability of the device. These factors will be simulated to find an optimised design before fabricating the device and conducting experimental tests to verify performance.
The final part of the research will entail combing the immobilisation technique with the optimised electrode design by integrating microfluidics into the device. The aim of this stage of research is to further improve the sensing capability whilst taking advantage of microfluidic behaviour. The performance of the microfluidic biosensor will be assessed by conducting field tests and evaluating the devices performance based on sensitivity, selectivity, limit of detection and detection time. This can then be compared against the performance of current monitoring techniques.