'Self-Healing Material for Lens Scratches Enables Autonomous Vehicle Functions to Recover When Exposed to Sunlight'... Development Announced

Domestic researchers have developed a lens material for autonomous vehicle sensors that heals surface scratches and restores optical functions when exposed to sunlight through a magnifying glass.

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The Korea Research Institute of Chemical Technology announced on the 20th that a research team led by Drs. Jincheol Kim, Youngil Park, and Jieun Jung, in collaboration with Professors Hakrin Kim and Inwoo Jung from Kyungpook National University, developed a material that self-heals scratches occurring on sensors of autonomous vehicles.

Building on last year’s technology for 'self-healing automotive coating materials activated by sunlight,' they advanced it to enable not only ‘structural recovery’ but also ‘functional recovery’ such as restoring optical signals. When applied to sensors in autonomous vehicles, this can extend the expected product lifespan. It is expected to secure future technology that can prevent malfunctions caused by surface damage.

Lenses are tools that gather or disperse light and are used in numerous everyday optical devices such as cameras, mobile phones, glasses, and distance-measuring sensors. However, when the lens surface is damaged by scratches, the images or optical signals received by the optical devices are severely distorted compared to reality. Repeated cases of traffic accidents caused by recognition errors and malfunctions in vision systems such as LiDAR sensors or image sensors in autonomous vehicles have lowered safety reliability. In fact, signal distortion caused by scratches on sensor surfaces poses a high risk of leading to autonomous vehicle traffic accidents.

The research team developed a transparent lens material that can remove scratches on sensor surfaces within 60 seconds by concentrating sunlight using a simple tool like a magnifying glass. For effective self-healing, molecular mobility within the polymer must be free and the material flexible; however, lens or lens-protective coating materials are generally made of hard substances, making it very difficult to impart self-healing functions. To solve this, the team designed a ‘dynamic chemical bond’ in which polymers repeatedly break and reform by mixing a transparent photothermal dye into a thiourethane structure already used as a lens material and then exposing it to sunlight.

In particular, they developed a transparent organic photothermal dye that selectively absorbs only specific near-infrared wavelengths (850?1050 nm) without interfering with the visible light range (350?850 nm) used by image sensors and the near-infrared range (~1550 nm) used by LiDAR sensors. When sunlight is absorbed by the developed material, light energy converts into heat energy, raising the surface temperature. As the temperature rises, polymers dissociate from their original network structure and repeatedly detach and reattach, enabling self-healing. Even when scratches intersect, 100% self-healing is achieved, and the material demonstrated excellent restoration by maintaining 100% self-healing efficiency after more than five cycles of scratching and healing at the same location.

While technologies to prevent sensor malfunctions caused by dust or surface contamination have been developed before, this is the first case of technology that restores physical damage on lens surfaces to prevent sensor malfunctions.

The research results were published in the February issue of the international scientific journal ‘ACS Applied Materials and Interfaces.’

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