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Title: Microfluidic biosensor systems for real-time in vivo clinical bioanalysis
Author: Gowers, Sally
ISNI:       0000 0004 6423 1457
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2015
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The aim of this thesis was to develop online biosensing systems for dialysate tissue metabo- lite detection in real time, to provide an insight into the health of tissue in various in vivo applications. An autocalibration system was developed using LabSmith programmable components to improve the accuracy of results obtained over long monitoring times. A method of col- lecting dialysate into storage tubes for online analysis while retaining temporal resolution was developed and validated. Microfluidic biosensor systems were developed for online measurement of glucose and lactate. One approach employed the use of biosensors, using a combined needle electrode with enzyme encapsulated in a hydrogel layer. The dynamic range of the biosensors was extended by adding an outer polyurethane layer. An alternative approach used automated syringe pumps and valves to develop a microfluidic system for in-flow enzyme addition to the dialysate stream. The existing rsMD system was applied for detection of tissue ischaemia during and after free flap surgery, by measuring dialysate glucose and lactate levels in real time. The system was able to detect flap failure, both during surgery and afterwards in the intensive therapy unit (ITU), much earlier than traditional methods. The rsMD system was adapted to enable monitoring of lactate levels in two dialysate streams and was applied for monitoring isolated porcine kidneys during two methods of cold preservation and subsequent re-warming. Significant differences in the lactate concentrations were observed between the two techniques. The system was extended for use with human transplant kidneys and with both porcine and human pancreases. A novel 3D printed wearable biosensor system was developed for direct integration with a clinical microdialysis probe. The system considerably improved the lag time and dispersional smearing compared with the existing rsMD system. The device was used in a proof-of-concept study with wireless potentiostats to monitor cyclists during exercise.
Supervisor: Boutelle, Martyn Sponsor: Engineering and Physical Sciences Research Council ; Imperial College London
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral