Just like other parts of the body, the retina needs oxygen in order to survive. If it doesn’t receive enough – should its blood supply be restricted, for instance – permanent blindness can result. Therefore, the sooner that doctors know if a patient’s retina is receiving insufficient oxygen, the better the chances that they can take action in time. Soon, they may be able to use tiny injectable robots to get them the information they need.
Led by Prof. Bradley Nelson, researchers at ETH Zurich had already created microrobots for possible use in delivering medication or removing scar tissue within the eye. The devices measure a millimeter in length and one third of a millimeter in width, and can be guided through the vitreous fluid within the eye via externally-applied magnetic fields.
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To turn the robots into oxygen sensors, the scientists coated them with nanospheres made of a dye created at Spain’s University of Granada. That dye fluoresces when exposed to a pulse of a specific wavelength of light – the faster that fluorescence subsequently fades, the higher the amount of oxygen in the dye’s immediate surroundings.
The dye-covered microrobots have already been successfully tested in water samples with varying oxygen levels. For their use in the eye, the idea is that they would first be injected into the vitreous fluid, and then steered toward the surface of the retina. A pulse of light would then be applied, with the duration of the robots’ resulting fluorescence being observed microscopically through the pupil.
When it came time to remove them, a needle could once again be inserted, and the robots would be magnetically attracted to it.
While there are already other methods of measuring oxygen levels within the eye, ETH claims that they aren’t sufficiently sensitive.