A team of Florida State University researchers has further developed a new generation of organic-inorganic hybrid materials that can improve image quality in X-ray machines, computed tomography and other radiation detection and imaging technologies.
Professor Biwu Ma, from the Department of Chemistry and Biochemistry, and his colleagues have developed a new class of materials that can act as highly efficient scintillators that emit light after being exposed to other forms of high-energy radiation, such as X-rays.
The team’s latest study, published in Advanced Materials, is an improvement on their previous research to develop better scintillators. The new design concept produces materials that can emit light within nanoseconds, orders of magnitude faster than previously developed materials, enabling better imaging.
“Reducing the radioluminescence lifetime of scintillators to nanoseconds is an important breakthrough,” Ma said. “Using a hybrid material made up of both organic and inorganic components means that each component can be used for the part of the process where it is most effective.”
WHY IS THIS IMPORTANT?
Scintillators are used in all kinds of imaging applications. Healthcare facilities, security x-rays, radiation detectors and other technologies use them and would benefit from better image quality.
The new generation of organic metal halide hybrid scintillators developed by Ma’s team has many improvements over existing ones. In addition to the significantly better radioluminescence response, the manufacturing process is simpler than that used for other scintillators and uses an abundance of inexpensive materials.
WHAT’S DIFFERENT ABOUT THIS SCINTILATOR?
Think of the scintillator as a kind of translator between two types of energy, taking a form of high-energy radiation, such as X-rays, and turning it into visible light. Less radiation passes through denser parts of an object, and this difference can be used to distinguish objects of higher density, such as bone or metal, from those of lower density, such as soft tissue. The radiation that passes through an object then interacts with the scintillator, which generates visible light that is detected by a sensor to make an image.
Today’s scintillators mainly use inorganic materials to transform high-energy radiation into visible light to create images. These materials are hard, use rare earth elements, and require energy-intensive, high-temperature manufacturing processes.
Ma and his team have been working on zero-dimensional organic metal halide hybrids, which they have pioneered since 2018. These organic-inorganic hybrids are made of small groups of negatively charged inorganic components, called metal halide clusters, and positively charged organic molecules. They are “zero-dimensional” at the molecular level because the metal halide clusters are completely isolated and surrounded by organic molecules.
In the first version of scintillators based on this material, metal halides absorb high-energy radiation and emit visible light. In this latest iteration, metal halide components and organic molecules work together. Metal halides absorb high-energy radiation and transfer energy to organic components that emit visible light.
Light emissions from organic molecules occur on the scale of nanoseconds, much faster than the microseconds or milliseconds it takes for metal halides to emit light.
“The faster the radioluminescence decays, the more precisely we can measure the timing of the photon emissions,” Ma said. “This results in higher resolution and contrast in the images.”
WHAT NEXT?
With help from FSU’s Office of Commercialization, Ma and his team have filed patents for organic metal halide hybrid scintillators. The office’s GAP Commercialization Investment Program provided technology development funding for potential partnerships with private companies that would make scintillators available on a wider scale.
“This is a continuation of our pursuit of better materials over the years, from 2018, when we first discovered this class of materials, to 2020, when we used them for scintillation for the first time,” Ma said. “This is another big breakthrough.”
This research was supported by the National Science Foundation and Florida State University.
The first author of this article was Tunde Blessed Shonde, a graduate student at FSU. Other co-authors include Maya Chaaban, He Liu, Oluwadara Joshua Olasupo, Azza Ben-Akacha, Fabiola G. Gonzalez, Kerri Julevich, Xinsong Lin, JS Raj Vellore Winfred, all of FSU, and Luis M. Stand and Mariya Zhuravleva of the University of Tennessee , Knoxville.