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Title: Spatially distributed microelectrode arrays in smart contact lenses : novel sensing designs, theory and methods
Author: Donora, Matthew
ISNI:       0000 0004 9348 5456
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2020
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Smart contact lenses (SCLs) are a new class of wearable medical device set to revolutionise the way we approach healthcare. SCLs have been designed for functions such as active vision correction, drug delivery, display technology and chemical sensing. By integrating electrochemical sensors into SCLs, continuous, unobtrusive and non-invasive monitoring of chemical markers in the tear film may be carried out. However, despite significant advances in the past few years, an electrochemical smart contact lens (ESCL) suitable for clinical use has not yet been demonstrated. There are still design challenges which need to be addressed before this technology matures into real medical utility. The primary issues facing ESCLs today are the construction of a safe, comfortable device, and the fidelity of the measurements made in the tear film when compared to an equivalent measurement in the blood. Recent advances in SCL platforms may be used to inform a new ESCL design, and address the issues of discomfort or safe use. A clinically approved SCL for glaucoma treatment is already used in hospitals around the world, offering hope of a clear path to an approved ESCL. However, the question of measurement fidelity may represent a greater challenge. In this thesis, a next-generation ESCL is designed, built and characterised. The physical design follows previous work towards soft SCL platforms, and represents a significant improvement on the current ESCL state-of-the-art. To improve the quality of the measurements taken in this device, advanced electrochemical sensors are first investigated and developed on flexible substrates suitable for SCL integration. In the final design, a set of spatially distributed, individually addressable microelectrode arrays are integrated into a soft ESCL. A new electrochemical method is also developed to perform video-rate spatiotemporal electrochemical sensing, with very low power requirements and a minimum of driving logic complexity. In addition, a neural network method is developed to correct for the measurement distortion inherent to taking measurements in the tear film and attempting to make conclusions about the equivalent measurement in the blood. In combination, this new design and methodology greatly improves both safety and comfort of the ESCL, and makes progress towards an ESCL capable of taking measurements continuously and unobtrusively with real clinical utility.
Supervisor: Underwood, Ian ; Walton, Anthony ; Dhillon, Baljean Sponsor: Engineering and Physical Sciences Research Council (EPSRC)
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: smart contact lenses ; electrochemical measurements ; tear film ; sensors ; wearable medical devices ; electrochemical smart contact lens ; electrochemical sensing