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

水污染监测的现状令人不满意。由于过时和不充分的监测制度和技术，意味着对水道污染程度的真正了解是不完整的。对水道中粪便物质的监测是通过检测粪便指示生物，特别是大肠杆菌和肠球菌的数量来实现的。由于目前的样品检测方法成本高，粪便污染监测的强度和频率受到限制。微流控生物传感装置的实施在增加监测频率、提供快速分析和降低成本方面具有巨大的潜力。本博士的目标是研究开发一种具有成本效益的微流控阻抗免疫生物传感器，用于实时检测水路样品中的大肠杆菌。同时解决生物传感装置实施的关键问题，如稳定性和可重复性。侧重于实现与当前监测技术相当的灵敏度、选择性和检测限，但检测时间要短得多。第一阶段的研究将集中于开发一种免疫传感器，通过将大肠杆菌抗体共价固定在电极表面。这为目标细菌提供了生物识别位点，当与阻抗谱分析技术相结合时，可以通过系统的电响应检测生物识别事件。第二阶段将研究优化电极设计。各种电极参数，如材料、尺寸和布局对器件的传感能力有重大影响。在制造设备并进行实验测试以验证性能之前，将模拟这些因素以找到优化设计。研究的最后一部分将需要通过将微流体集成到设备中，将固定技术与优化的电极设计结合起来。本阶段研究的目的是在利用微流体特性的同时进一步提高传感能力。微流控生物传感器的性能将通过现场测试和基于灵敏度、选择性、检测极限和检测时间的设备性能评估来评估。然后可以将其与当前监测技术的性能进行比较。

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 With outdated and inadequate monitoring regimes and techniques meaning that a true understanding of the level of pollution in waterways is incomplete.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.