2024-03-15 16:06:12
Neuroprosthetics, a booming field of research, focuses on designing devices capable of interacting with the nervous system to restore lost functions. This technology might significantly improve the quality of life of people with sensory impairments.
The cochlear implant, which converts sounds into electrical signals directly stimulating the auditory nerve in people with severe hearing loss, is an iconic example of this technology. The question now arises whether a similar approach might be applied to restore vision in people whose photoreceptors, cells responsible for detecting light and color, are damaged.
A multidisciplinary group of researchers, including engineers, neuroscientists, clinicians and other biotechnology experts, are convinced of the potential of this technology, although progress is made in incremental steps.
Dr Udo Roemer: at the crossroads of photovoltaics and vision
UNSW researcher and photovoltaics engineer Dr Udo Roemer is interested in using solar technology to convert light entering the eye into electricity. This approach might bypass damaged photoreceptors and transmit visual information to the brain.
« People with conditions such as retinitis pigmentosa and age-related macular degeneration gradually lose vision as the photoreceptors in the center of the eye degenerate “, explains Dr. Roemer. He envisions that biomedical implants in the retina might replace faulty photoreceptors. Using electrodes to create an electrical pulse might allow patients to perceive a spot of light.
Dr. Udo Roemer. Photo: Robert Largent
However, current trials of this technology require inserting wires into the eye, a complex procedure.
A wireless option
The alternative studied by Dr. Roemer consists of a tiny solar panel fixed on the eye, transforming the light into an electrical impulse that the brain uses to create our visual field. This panel would be self-contained and portable, eliminating the need for cables and wires.
Dr. Roemer is not the first to explore the use of solar cells to restore eyesight. It focuses on semiconductor materials such as gallium arsenide and indium gallium phosphide, which allow better tailoring of cell properties and are used in the solar industry for their efficiency, although they are more expensive than general-purpose silicon.
« To stimulate neurons, a voltage greater than that provided by a single solar cell is required », Specifies Dr Roemer. If we compare photoreceptors to pixels, it would take three solar cells stacked on top of each other to generate sufficient voltage. Gallium arsenide facilitates this superposition compared to silicon.
The research is at the proof of concept stage. Two solar cells have been successfully superimposed in the laboratory on an area of approximately 1 cm², giving promising results. The next step will be to shrink these cells to the pixel size needed for vision and etch the grooves to separate them, before increasing the battery to three solar cells.
Dr. Roemer envisions that this technology, following extensive testing in the laboratory and in animal models, might be tested in humans. The device would measure approximately 2 mm² with pixels of approximately 50 micrometers. However, he points out that the intensity of sunlight alone may not be enough for these solar cells implanted in the retina.
Patients may need to wear smart glasses or special glasses that work in concert with solar cells to amplify the solar signal to the intensity needed to reliably stimulate the eye’s neurons.
« It should be noted that even with the efficiency of stacked solar cells, sunlight alone may not be powerful enough to work with these solar cells implanted in the retina “, he explains.
« People may need to wear glasses or smart glasses that work in tandem with the solar cells that can amplify the solar signal to the intensity needed to reliably stimulate the eye’s neurons. »
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