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Liquid crystals produce easily readable, color-changing sensors

Liquid crystals produce easily readable, color-changing sensors

PME scientists and engineers have developed a method to stretch and tension liquid crystals to produce different colors. This could be used in intelligent coatings, sensors and portable electronics. Photo credit: Oleg Lavrentovich, Liquid Crystal Institute, Kent State University

Chameleons are famous for their color-changing skills. Depending on their body temperature or mood, their nervous system drives skin tissue that contains nanocrystals to expand or contract, change the way the nanocrystals reflect light, and transform the reptile̵

7;s skin into a rainbow of colors.

Inspired by this, scientists from the Pritzker School of Molecular Engineering (PME) at the University of Chicago have developed a way to stretch and stretch liquid crystals to produce different colors.

By creating a thin polymer film that is filled with liquid crystal droplets and then manipulating it, they have established the basics for a color change sensor system that can be used for smart coatings, sensors, and even portable electronics.

The research, led by Juan de Pablo, professor of molecular technology in the Liew family, was published in the journal on July 10 Advances in science.

Stretching fluid with thin films

Liquid crystals with different molecular orientations are already the basis for many display technologies. But de Pablo and his team were interested in chiral liquid crystals that have twists and turns and a certain asymmetrical “handedness” – such as right-handed or left-handed – that allows them to show more interesting optical behaviors.

These crystals can also form so-called “blue phase crystals”, which have the properties of both liquids and crystals and, in some cases, can better transmit or reflect visible light than liquid crystals themselves.

The researchers knew that these crystals could potentially be manipulated to achieve a variety of optical effects when stretched or stretched. However, they also knew that it is not possible to directly stretch or stretch a liquid. Instead, they placed tiny liquid crystal droplets in a polymer film.

“In this way, we could encapsulate chiral liquid crystals and deform them in very specific, highly controlled ways,” said de Pablo. “This way you can understand what properties they can have and what behaviors they have.”

Creation of temperature and strain sensors

In this way, the researchers found many more different phases – molecular configurations of the crystals – than previously known. These phases produce different colors depending on how they are stretched or stretched or even if they are subject to temperature changes.

“Now the possibilities are really open to the imagination,” said de Pablo. “Imagine using these crystals in a textile whose color changes depending on the temperature or whose color changes when you bend your elbow.”

Such a system could also be used, for example, to measure the strain in aircraft wings or to detect minute changes in temperature in a room or system.

Color changes are a great way to measure something remotely without the need for contact, said de Pablo.

“You can simply look at the color of your device and see how heavily it is loaded, and take corrective action if necessary,” he said. “For example, if a structure is overstressed, the color can change immediately and close to repair it. Or if a patient or an athlete places too much stress on a particular body part during movement, they could wear a fabric to measure it and then try to correct it. “

Although the researchers manipulated the materials with strain and temperature, there is also the potential to influence them with voltage, magnetic fields, and acoustic fields, which could lead to new types of electronic devices made from these crystals.

“Now that we have basic research to understand how these materials behave, we can apply them to different technologies,” said de Pablo.

Scientists are creating a “crystal in a crystal” for new electronic devices

More information:
“Multiply and flatten chiral liquid crystal spheroids” Advances in science (2020). DOI: 10.1126 / sciadv.aba6728, advanced.sciencemag.org/content/6/28/eaba6728

Provided by the University of Chicago

Quote: Liquid crystals produce easily readable, color-changing sensors (2020, July 10), which were accessed on July 10, 2020 from https://phys.org/news/2020-07-liquid-crystals-easy-to-read-color -changing-sensors.html

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