Tuneable liquid crystal lasers for fluorescence-based retinal disease diagnostics

This project develops new tuneable and highly-customisable liquid crystal laser sources, and applies them to the field of fluorescence-based retinal imaging, for the detection of age-related macular degeneration and other ophthalmic diseases.

Autofluorescent (or fluorescent-tagged) biomarkers such as lipofuscin, within the retinal pigment epithelium, can be optically probed using lasers to search for ophthalmic abnormalities. Despite the potential capabilities of this technique, its clinical adoption is restricted to specialist laboratories. Each fluorescent biomarker has its own specific optical absorbance, and so equipment must compromise between detection versatility (i.e. containing multiple lasers of different wavelengths, each targeting a different marker, and hence be large, bulky and expensive), or portability (i.e. contain only a single laser source addressing a single fluorophore, and hence be small and portable). Compromised systems must also be built around the availability of existing light sources, which do not cover the full colour spectrum, resulting in poor signal strength and signal ambiguity due to mismatching/overlapping absorbances between multiple fluorophores.

Liquid crystal (LC) lasers use self-assembling chiral nanostructures to create tuneable laser cavities only 10 µm thick, and when doped with organic dyes enable highly efficient and customisable laser emission over the visible spectrum (450-850 nm). They have potential as small, low-cost, switchable and tuneable light sources for medical imaging applications, thus eliminating the requirement to compromise between versatility, portability and cost; potentially enabling cheaper, smaller and more effective diagnostics tools. Tuneable LC lasers can be designed to perfectly match the absorbance requirements of biomarkers, maximising detection capabilities. They also provide a simple route to providing new modalities of detection, such as ratiometric imaging and fluorescence lifetime imaging, through temporal control of rapidly changing pulsed wavelength patterns.

Working in collaboration with engineers, biomedical scientists, ophthalmic clinicians and industry partners on a highly interdisciplinary project, the student will demonstrate a proof-of-concept system using LC lasers to perform clinically-relevant fluorescence imaging of the retina for disease diagnostics. They will use cleanroom microfabrication, opto-mechanical and electro-optical approaches to construct bespoke LC laser and microscope systems (with properties including tuneable wavelengths and temporal control of single or multiple simultaneous beams). LC lasers will be designed to optimally probe multiple common fluorescent retinal markers simultaneously, and their performance advantages compared to conventional sources will be validated. Further investigations will include the clinical opportunities of techniques such as ratiometric imaging and fluorescence lifetime imaging to provide improved data to the field of point-of-care ophthalmic disease detection. Opportunities for commercial development will also be explored, in collaboration with our industrial partners.