An international team of researchers have borrowed from nature to develop a new class of nanoscale materials that could facilitate improvement in medical imaging.
Eye of a moth as seen through a scanning electron microscope (credit: Dartmouth College)
The team led by Professor Yasha Yi from the City University of New York has modeled the nanostructures after the compound eyes of the moth. Moths’ eyes consist of thousands of optical units or ommatidia. The optical units are attached to photoreceptor cells. They are however, anti-reflective. This provides a moth covert mobility and reduced visibility to predators at nights. This feature makes the moth eye appealing to scientists for adapting the same design in antireflective surfaces for military use and in solar panel coatings.
Scintillating materials are compounds employed in radiographic imaging devices for converting unabsorbed portions of incident X-rays exiting the body into visible light that can be formulated into a shape by means of a detector. Better quality imaging is achieved by increasing the radiation input in order to increase the visible light output. But increased exposure to radiation is detrimental to patients’ health. Yi’s team worked on developing a nanoscale film for the scintillators to increase the efficiency of light conversion. The 500-nm thick film was made from cerium-doped lutetium oxyorthosilicate crystals. Tiny, pyramid-shaped silicon nitride protrusions were embedded on the film. The density of the protuberances is similar to that of the moth eye and is in the range of 100,000 to 200,000 in a 100 x 100 µm2. The team made the device side walls rough to enhance the ability to scatter light. Lab experiments showed a drastic 175% increase in the intensity of emitted light. Yi envisages a time period of three to five years for perfecting the film to move it from the lab to imaging devices.
Source: http://www.opticsinfobase.org/