Scientists have developed innovative contact lenses that can display 3D holograms using specialized nanostructures embedded on them called metasurfaces.
According to the news agency of Science and Technology Anna, citing Azadones Science, metamaterials are engineered materials that have properties that are not found in nature. As its name suggests, a metasurface is a type of metamaterial that is simply applied to a surface. These structures are often smaller than the wavelength of light, enabling them to manipulate electromagnetic waves such as light and sound in unique ways.
“Ultrasurfaces manipulate light with high precision,” says Junsuk Rho, a researcher at Pohang University of Science and Technology in South Korea and lead author of the project.
Why trans level?
Metasurface materials have proven useful in fields such as biomedicine, speech recognition, and energy harvesting, but their integration into contact lenses for virtual reality and augmented reality is difficult. However, their potential to surpass current technologies in significant ways makes them compelling.
“These augmented reality contact lenses could offer significant advantages over existing technologies,” Rowe said. There are usually gratings, prisms, or mirrors to provide a virtual image of a display source located near the temple to the retina. At the same time, the actual scene lighting should be free of unwanted diffraction effects. Due to the complexity of these design requirements, the optical system becomes bulky.
He continued: “Since the lenses are placed directly on the eye, they maintain a natural field of vision and provide an unparalleled level of immersion without the limitations imposed by external devices such as headsets or glasses.”
Apart from entertainment and gaming, there are many applications for this technology, from environmental monitoring, identity recognition, recognition and real-time navigation to providing directions and textual information directly in the user's field of vision.
“In environments such as healthcare, lenses can assist surgeons by embedding critical information during surgery,” Rowe said. Additionally, the lenses can display real-time biometric data for personal health monitoring purposes.”
But before any of this can come to fruition, the hurdles inherent in supersurface production must be overcome. First, it is important to ensure the biocompatibility of the material, as contact lenses interact directly with the eye. Traditional methods of nanostructure transfer often do not consider long-term biocompatibility, raising concerns about safety during long-term wear.
Second, it is difficult to maintain structural stability due to the flexible and wet nature of contact lenses, which can lead to deformation or damage of the nanostructures; And finally, achieving accurate pattern transfer on a flexible substrate such as a contact lens is technically challenging.
Rowe and his colleagues, who have been working on the field since 2008, were motivated by developing a new manufacturing method to overcome the challenges associated with incorporating metamaterials into contact lenses. Their approach relies on hyaluronic acid; A naturally occurring molecule found throughout the body, especially in the eyes, joints, and skin.
“We use it as a soft template that allows smooth transfer of complex nanostructures onto the lens surface without compromising the structural integrity of the surface,” he explained. This substance plays an important role in the biocompatibility and performance of contact lenses.
Metasurfaces are usually created using advanced fabrication methods such as photolithography or electron beam exposure. These methods involve coating a surface with a light-sensitive material, exposing it to light or electrons through a coverslip, and developing a pattern.
After this, other materials of interest, such as electronic semiconductors, are placed on the patterned substrate and etched to form the final nanostructures that are small enough to modulate or shape electromagnetic radiation. After the metasurface is completed, it is transferred from the temporary substrate to the final material such as a contact lens.
In their manufacturing process, these researchers used gold deposition on a flexible, rubber-like material called polyurethane acrylate, which acts as the first mold for the constructed surface. This 3D patterned gold layer is then transferred from this initial mold to a second hydrated hyaluronic acid layer – for its final transfer to the contact lens – which is then covered with a protective silicone layer.
Korean researchers say: “The SiO 2 protective layer between the contact lens material and the gold patterns prevents direct contact with the eye, thereby minimizing the potential risk of side effects.”
The silicon layer also acts as a waveguide that directs electromagnetic waves from one point to another, increasing not only the stability of the lens, but overall performance.
Now comes the exciting part of the project: creating holograms using the metasurfaces embedded in the new lenses.
When light hits the metasurface—this could be from a controlled light source from a wearable device or perhaps even sunlight—each tiny, carefully designed component changes the intensity, angle, and direction of the light to create a holographic image that can The observation is making.
In this technology, the images are static, but the researchers plan to develop it so that it can produce dynamic holographic videos by embedding a metasurface designed to act as a emitter and light source, such as micro-LEDs, in contact lenses.
Before any of this, safety must be fully evaluated and the technology further developed. The next steps include extensive live testing to evaluate the long-term safety and performance of the lenses in real-world conditions.
The scientists plan to refine the manufacturing process to ensure scalability and affordability for commercial production. Regulatory approvals will also be a critical step, as they must demonstrate compliance with medical device safety standards.
