Researchers at MIT have developed a family of materials that can emit light of precisely controlled colors — even pure white light — and whose output can be tuned to respond to a wide variety of external conditions. The materials could find a variety of uses in detecting chemical and biological compounds, or mechanical and thermal conditions.
The material, a metallic polymer gel made using rare-earth elements, is described in a paper in the Journal of the American Chemical Society.
The material, a light-emitting lanthanide metallogel, can be chemically tuned to emit light in response to chemical, mechanical, or thermal stimuli — potentially providing a visible output to indicate the presence of a particular substance or condition.
The new material is an example of work with biologically inspired materials. The use of a metal from the lanthanide group, also known as rare-earth elements, combined with a widely used polymer called polyethylene glycol, or PEG, results in a material that produces tunable, multicolored light emissions.
The light emission can then reflect very subtle changes in the environment, providing a color-coded output that reveals details of those conditions.
So, for example, the materials could be engineered to detect specific pollutants, toxins, or pathogens, with the results instantly visible just through color emission.
The materials can also detect mechanical changes, and could be used to detect stresses in mechanical systems. For example, it’s difficult to measure forces in fluids, but this approach could provide a sensitive means of doing so.
The material can be made in a gel, a thin film, or a coating that could be applied to structures, potentially indicating the development of a failure before it happens.
Metal-coordination bonds in polymers have been the subject of other work by the researcher: In a separate paper the researchers published Aug. 31 in the journal Nature Materials, they reported making polymers with tunable mechanical properties, including stiffness. These materials are naturally self-assembling and self-healing, and could be useful as energy-absorbing materials or in biological implants that need to be able to absorb impacts without breaking.
