First wireless OLED contact lens for wearable diagostics
A team of Korean researchers has developed a next-generation wireless ophthalmic diagnostic technology that replaces the existing stationary, darkroom-based retinal testing method by incorporating an “ultrathin OLED” into a contact lens.
The technology enables Electroretinography (ERG) simply by wearing the lens, eliminating the need for large specialised light sources. It dramatically simplifies the conventional, complex ophthalmic diagnostic environment. ERG is an ophthalmic diagnostic method used to determine whether the retina is functioning normally. ERG is used widely for diagnosing hereditary retinal diseases or assessing retinal function decline.
The breakthrough is expected to find applications in diverse fields such as myopia treatment, ocular biosignal analysis, augmented-reality (AR) visual information delivery, and light-based neurostimulation.
This technology enables ERG simply by wearing the lens, eliminating the need for large specialised light sources and dramatically simplifying the conventional, complex ophthalmic diagnostic environment.
Traditionally, ERG requires the use of a stationary Ganzfeld device in a dark room, where patients must keep their eyes open and remain still during the test. This setup imposes spatial constraints and can lead to patient fatigue and compliance challenges.
To overcome these limitations, the joint research team integrated an ultrathin flexible OLED with an approximate thickness of 12.5 μm, or 6–8 times thinner than a human hair, into a contact lens electrode for ERG. They also equipped it with a wireless power receiving antenna and a control chip, completing a system capable of independent operation.
For power transmission, the team adopted a wireless power transfer method using a 433 MHz resonant frequency suitable for stable wireless communication. The researchers also demonstrated a wireless controller embedded in a sleep mask, which can be linked to a smartphone, further enhancing practical usability.
While most smart contact lens–type light sources developed for ocular illumination have used inorganic LEDs, these rigid devices emit light almost from a single point, which can lead to excessive heat accumulation and thus usable light intensity. In contrast, OLEDs are area light sources and were shown to induce retinal responses even under low luminance conditions. In this study, under a relatively low luminance of 126 nits, the OLED contact lens successfully induced stable ERG signals, producing diagnostic results equivalent to those obtained with existing commercial light sources.
Animal tests confirmed that the surface temperature of a rabbit’s eye wearing the OLED contact lens remained below 27°C, avoiding corneal heat damage, and that the light-emitting performance was maintained even in humid environments, demonstrating its effectiveness and safety as an ERG diagnostic tool in real clinical settings.
Professor Seunghyup Yoo from the KAIST School of Electrical Engineering who led the research team, stated that “integrating the flexibility and diffusive light characteristics of ultrathin OLEDs into a contact lens is a world-first attempt,” and that “this research can help expand smart contact lens technology into on-eye optical diagnostic and phototherapeutic platforms, contributing to the advancement of digital healthcare technology.”
Image: ID-style photograph against a laboratory background featuring an OLED contact lens sample (centre), flanked by the principal authors (left: Professor Seunghyup Yoo; right: Dr. Jee Hoon Sim). Above them (from top to bottom) are: Professor Se Joon Woo, Professor Sei Kwang Hahn, Dr. Su-Bon Kim, and Dr. Hyeonwook Chae. Credit KAIST.
Paper: https://doi.org/10.1021/acsnano.4c18563
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