Doubly photopolymerised holographic sensors
File(s)
Author(s)
Davies, Sam
Type
Thesis
Abstract
With expanding and aging populations globally, pressure on healthcare systems is expected to increase in coming decades. The requirement for next generation point-of-care biosensors to monitor population health is an emerging necessity for medical providers to maintain patient treatment quality. Point-of-care devices can permit patients to obtain medical data without medical professional involvement, potentially increasing measurement frequency and reducing the requirement for doctors or patients to attend appointments. Holographic sensors are uniquely placed to fulfil this requirement through low-cost fabrication, and colourimetric, reversible, and rapid readouts. The scope of this thesis is to expand the seldomly reported, doubly UV photopolymerised holographic sensor platform, including chemical functionalisation and provide evidence of viability in point-of-care applications. Double photopolymerised holographic sensors utilise a single coherent UV laser pulse (5 ns, 355 nm) to photopolymerise highly crosslinked nano-fringes, fabricating a Bragg mirror structures within a responsive hydrogel material from two distinct polymers. Holographic sensor parameters have been computationally modelled through COMSOL Multiphysics® to determine the dynamic relationship between recording, response, and fabrication parameters. Viable colourimetric sensors for real-time determination of pH and glucose concentration have been fabricated and verified in biological samples (blood serum and urine, respectively) with Bragg wavelength shifts of 90-170 nm over physiological ranges (pH = 7-9, glucose = 0.0-9.4 mmol L-1). Each sensor utilizes a different hydrogel base network (pH: (hydroxyethyl)methacrylate, glucose: acrylamide) indicating the platforms potential for future applications. This thesis presents a nanoparticle free holographic sensing platform which has been functionalised through co-monomer incorporation for application in point-of-care testing, with optimisation of parameters applicable to future systems for controlling sensitivity, response time, replay wavelength, and diffraction efficiency.
Version
Open Access
Date Issued
2022-12-14
Date Awarded
01/10/2023
License URL
Advisor
Yetisen, Ali
Sponsor
Engineering and Physical Sciences Research Council
Grant Number
EP/T013567/1
Publisher Department
Chemical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)