An Organic Approach to Full-Colour Vision Restoration: Using conjugated semiconductors for an improved artificial retina
Creators: name: Askew, Leslie
Publisher: name: University of Surrey
Year: 2023

description: This work presents a feasibility study focused on the application of conjugated semiconducting materials for the development of an artificial retina. With millions of people worldwide affected by retinal dystrophies leading to vision loss, an artificial retina offers a technological treatment that complements existing genetic therapies. The success of this prosthetic relies on achieving absorption and electrical response profiles that closely match those of natural photoreceptors.<br>
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description: While the focus of this study is on the materials used in the artificial retina, it is important to note that the ultimate goal of the research is to develop a functional artificial retina. The subretinal placement of the artificial retina plays a crucial role in harnessing the network processing power of the retina. However, the specific efficacy and performance evaluation of the functional materials within the artificial retina are the primary objectives of this study. The study investigates various materials, including small molecules, polymers, conjugated polymeric nanoparticles, and bulk heterojunctions with both fullerenes and non-fullerene acceptors, within an electrolytic environment. In order to assess the progress of the investigation, an extensive review of the existing literature was undertaken to establish reference points for evaluation. Among the various benchmarks considered, a rough guideline of -330 mV extracellular voltage emerged as the most relevant for generating a sufficient electrical field to elicit a measurable stimulus. However, the targeting of bipolar cells presents a challenge due to their graded response characteristics, which complicates the definition of a specific threshold for effective stimulation.<br>
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description: Experimental measurements were carried out to assess absorption, spectral photo response, and transient photocurrent and photovoltage characteristics. Specialized equipment was developed during the course of the doctoral programme to facilitate these measurements. The results demonstrate that small molecules and conjugated polymeric nanoparticles show promising potential in generating the required voltage levels. Additionally, the inclusion of acceptor molecules improves the device response to operational levels under ambient light conditions. However, careful consideration must be given to the potential mismatch between the absorption spectra of the materials and natural photoreceptors, necessitating further investigation.<br>
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description: This feasibility study highlights the potential of conjugated semiconducting materials for the development of an artificial retina. The progress made in generating the required voltage levels particularly with small molecules and conjugated polymeric nanoparticles, is encouraging. The use of acceptor molecules enhances the device response to meet operational levels under ambient light conditions. However, optimising the absorption spectra to better match that of photoreceptors remains a critical area for further investigation. These findings pave the way for future advancements in the field of artificial retina development, offering hope to individuals affected by retinal dystrophies.<br>