Nanostructures modeled after moth eyes may enhance medical imaging
Using the compound eyes of the lowly moth as their inspiration, an international team of physicists has developed new nanoscale materials that could someday reduce the radiation dosages received by patients getting X-rayed, while improving the resolution of the resulting images.
Published on: Mar 3, 2016
Transcripts - Nanostructures modeled after moth eyes may enhance medical imaging
Nanostructures modeled after moth eyes may enhance medical imagingUsing the compound eyes of the lowly moth as their inspiration, an international team of physicists hasdeveloped new nanoscale materials that could someday reduce the radiation dosages received bypatients getting X-rayed, while improving the resolution of the resulting images.The work, led by Yasha Yi—a professor of the City University of New York, who is also affiliated withMassachusetts Institute of Technology and New York University—was published today in the OpticalSocietys journal, Optics Letters.Like their Lepidopteran cousins the butterflies, moths have large compound eyes, made up of manythousands of ommatidia—structures made up of a primitive cornea and lens, connected tophotoreceptor cells. But moth eyes, unlike those of butterflies, are remarkably anti-reflective, bouncingback very little of the light that strikes them. The adaptation helps the insects be stealthier and lessvisible to predators during their nocturnal flights. Because of this feature, engineers have looked to themoth eye to help design more efficient coatings for solar panels and antireflective surfaces for militarydevices, among other applications.Now Yi and his colleagues have gone a step further, using the moth eye as a model for a new class ofmaterials that improve the light-capturing efficiency of X-ray machines and similar medical imagingdevices.In particular, the researchers focused on so-called “scintillation” materials: compounds that, whenstruck by incoming particles (say, X-ray photons), absorb the energy of the particles and then reemit thatabsorbed energy in the form of light. In radiographic imaging devices, such scintillators are used toconvert the X-rays exiting the body into the visible light signals picked up by a detector to form animage.One way to improve the output (the intensity of light signals read by the detector, and thus theresolution of the resulting images) is to increase the input—that is, to use a higher x-ray dosage. Butthat’s not healthy for patients because of the increased levels of radiation. An alternative, Yi andcolleagues figured, is to improve the efficiency with which the scintillator converts X-rays to light. Theirnew material does just that.It consists of a thin film, just 500 nanometers thick, made of a special type of crystal known as cerium-doped lutetium oxyorthosilicate. These crystals were encrusted with tiny pyramid-shaped bumps orprotuberances made of the ceramic material silicon nitride. Each protuberance, or “corneal nipple,” ismodeled after the structures in a moth’s eye and is designed to extract more light from the film.
Between 100,000 to 200,000 of the protuberances fit within a 100 x 100 micrometer square, or aboutthe same density as in an actual moth eye. The researchers then made the sidewalls of the devicerougher, improving its ability to scatter light and thus enhancing the efficiency of the scintillator.In lab experiments, Yi and colleagues found that adding the thin film to the scintillator of an X-raymammographic unit increased the intensity of the emitted light by as much as 175 percent compared tothat produced using a traditional scintillator.The current work, Yi says, represents a proof-of-concept evaluation of the use of the moth-eye-basednanostructures in medical imaging materials. “The moth eye has been considered one of the mostexciting bio structures because of its unique nano-optical properties,” he says, “and our work furtherimproved upon this fascinating structure and demonstrated its use in medical imaging materials, whereit promises to achieve lower patient radiation doses, higher-resolution imaging of human organs, andeven smaller-scale medical imaging. And because the film is on the scintillator,” he adds, “the patientwould not be aware of it at all.”Yi estimates that it will take at least another three to five years to evaluate and perfect the film, and testit in imaging devices. “We will need to work with medical imaging experts and radiologists for this to beactually used in clinical practice,” he says.The work was done in collaboration with Professors Bo Liu and Hong Chen of Tongji University inShanghai.Giant light extraction enhancement of medical imaging scintillation materials using biologically inspiredintegrated nanostructuresOptical Society of America--------Source: http://www.rdmag.com/News/2012/07/Life-Science-Optics-Medical-Technology-Nanostructures-modeled-after-moth-eyes-may-enhance-medical-imagingThis is what we feel:Acroseas strongly believes that the days of one-system, one-solution is long gone and the future holds inone-solution, many systems.