Two liquid crystal studies conducted by a professor and a team of seven graduate students at Kent State University have been awarded a combined $990,000 in grants by the National Science Foundation.
Liquid crystals, as defined by The Nature Journal, are “substances that flow like a liquid but maintains some of the ordered structure of crystals. Their molecules tend to orient in the same direction. They are often used in screens of digital devices, like smartphones and laptops, for their light modulating properties.”
Led by Oleg Lavrentovich, trustees research professor at Kent State’s Advanced Materials and Liquid Crystal Institute, the studies will be exploring the ways in which liquid crystal structure may be used to further developments in biomedical and digital tech industries.
Lavrentovich received $540,000 for a three-year study focused on “electrically tunable cholertic optical filters,” which is the practice of using liquid crystal molecules to replace permanent optic filters in screens and lenses in devices such as cameras or display screens for a more diverse and adjustable field of color.
“This grant is for the exploration of optics and physics in liquid crystals that allow you to change the color by simply changing the voltage applied,” Lavrentovich said.
Lavrentovich explained that applying a voltage through a layer of liquid crystal molecules between two glass plates will change the reflected color by altering the molecular structure. Each voltage level corresponds with a specific wavelength that reflects a specific color.
“Liquid crystals of the choleristic type studied in this project have a very interesting structure,” Lavrentovich said. “The molecules twist from the top plate to the bottom plate in an oblique helicoidal state, [similar to a DNA helix]. If you apply voltage, it is like stretching a slinky or shrinking it which will change the period. Only the light with wavelengths that correspond to this periodicity is being reflected.”
This technique could be used in multiple ways. Windows with a film of liquid crystal could be used to block heat carried in through light wavelengths, from entering or escaping a building. Agricultural drones that use imaging to monitor crop growth could use the electric liquid crystal tuning to capture more detailed images.
This liquid crystal technique could also lead to developments in the medical field.
“This method could be used medically in multispectral imaging diagnostics,” Lavrentovich said. “The images would show a wider range leading to a more accurate diagnosis.”
The second grant, a $450,00 project, will propagate Lavrentovich’s previous study in using the liquid crystal structure to control the direction in which bacteria and synthetic particles move.
Lavrentovich states that bacterial movement, which is disorganized and unpredictable, could be controlled and targeted by placing it in a liquid crystal environment.
“Our question with this study is, ‘can we impose our will on this chaotic behavior? Can we rectify it with the liquid crystal?’” Lavrentovich said. “A liquid crystal is a fluid that has some structure and some orientational order. If we combine the bacteria with a liquid crystal, the bacterium swim in the liquid crystal which is aligned horizontally in a motion that is straight and parallel to the surrounding liquid crystal”
The direction and track of the bacteria can be altered according to the specific structure of the liquid crystal itself.
While it’s still in the fundamental stages, this study could have applications in the biomedical field.
“Maybe 50 years from now this may have an application,” Lavretovich said. “This just inspires us. We don’t know what will be the complete usage, but there will be a lot of it.”
As for the future of the liquid crystal, Lavrentovich sees it being used for more than just phone screen displays.
“Many people are very interested in studying liquid crystals further,” Lavrentovich said. “People hope there is much more to extract from liquid crystals in practical applications for the future.”
Colleen Carroll is a science reporter. Contact her at [email protected]