Moth eye inspires radiation-reducing materials
Like butterflies, they have large compound eyes (pictured) made of thousands of tiny photoreceptors. But moth eyes are also anti-reflective, bouncing back very little of the light that strikes them. This stealthy adaption makes them less visible to predators at nighttime.
Their eyes have inspired solar panel coatings and military device. Now, to lower radiation doses, a team led by Yasha Yi of City University of New York looks to moth eyes to improve the light-capturing efficiency of X-rays and other medical imaging devices.
In particular, ’scintillation’ materials absorb the energy of X-ray photons and then reemit that absorbed energy in the form of light. These convert X-rays exiting the body into the visible light signals picked up by a detector to form an image.
Yi’s team wanted to improve the scintillator’s efficiency in converting X-rays to light. According to the Optical Society:
- Their thin, bioinspired film (500 nanometers thick, pictured below) is made of a crystal called cerium-doped lutetium oxyorthosilicate.
- These crystals are encrusted with tiny pyramid-shaped bumps (called ‘corneal nipples’) made of a ceramic material.
- The corneal nipple — modeled after structures in the moth eye — is designed to extract more light from the film.
- Up to 200,000 of these corneal nipples fit within a tiny square about the density of an actual moth eye.
- They made the sidewalls of this device rougher, improving its ability to scatter light, enhancing the efficiency of the scintillator.
The new nanomaterial also promises to improve the resolution of the resulting medical images.
[Via OSA news]
Images: eye from Dartmouth, nanostructure from Optics Letters