Tag Archives: Debashis Chanda

A structural colour solution for energy-saving paint (thank the butterflies)

The UCF-developed plasmonic paint uses nanoscale structural arrangement of colorless materials — aluminum and aluminum oxide — instead of pigments to create colors. Here the plasmonic paint is applied to the wings of metal butterflies, the insect that inspired the research. Credit: University of Central Florida

A March 9, 2023 news item on Nanowerk announces research into multicolour energy-saving coating/paint, so, this is a structural colour story, Note: Links have been removed,

University of Central Florida researcher Debashis Chanda, a professor in UCF’s NanoScience Technology Center, has drawn inspiration from butterflies to create the first environmentally friendly, large-scale and multicolor alternative to pigment-based colorants, which can contribute to energy-saving efforts and help reduce global warming.

A March 8, 2023 University of Central Florida (UCF) news release (also on EurekAlert) by Katrina Cabansay, which originated the news item, provides more context and more details,

“The range of colors and hues in the natural world are astonishing — from colorful flowers, birds and butterflies to underwater creatures like fish and cephalopods,” Chanda says. “Structural color serves as the primary color-generating mechanism in several extremely vivid species where geometrical arrangement of typically two colorless materials produces all colors. On the other hand, with manmade pigment, new molecules are needed for every color present.”

Based on such bio-inspirations, Chanda’s research group innovated a plasmonic paint, which utilizes nanoscale structural arrangement of colorless materials — aluminum and aluminum oxide — instead of pigments to create colors.

While pigment colorants control light absorption based on the electronic property of the pigment material and hence every color needs a new molecule, structural colorants control the way light is reflected, scattered or absorbed based purely on the geometrical arrangement of nanostructures.

Such structural colors are environmentally friendly as they only use metals and oxides, unlike present pigment-based colors that use artificially synthesized molecules.

The researchers have combined their structural color flakes with a commercial binder to form long-lasting paints of all colors.

“Normal color fades because pigment loses its ability to absorb photons,” Chanda says. “Here, we’re not limited by that phenomenon. Once we paint something with structural color, it should stay for centuries.”

Additionally, because plasmonic paint reflects the entire infrared spectrum, less heat is absorbed by the paint, resulting in the underneath surface staying 25 to 30 degrees Fahrenheit cooler than it would if it were covered with standard commercial paint, the researcher says.

“Over 10% of total electricity in the U.S. goes toward air conditioner usage,” Chanda says. “The temperature difference plasmonic paint promises would lead to significant energy savings. Using less electricity for cooling would also cut down carbon dioxide emissions, lessening global warming.”

Plasmonic paint is also extremely lightweight, the researcher says.

This is due to the paint’s large area-to-thickness ratio, with full coloration achieved at a paint thickness of only 150 nanometers, making it the lightest paint in the world, Chanda says.

The paint is so lightweight that only about 3 pounds of plasmonic paint could cover a Boeing 747, which normally requires more than 1,000 pounds of conventional paint, he says.

Chanda says his interest in structural color stems from the vibrancy of butterflies.

“As a kid, I always wanted to build a butterfly,” he says. “Color draws my interest.”

Future Research

Chanda says the next steps of the project include further exploration of the paint’s energy-saving aspects to improve its viability as commercial paint.

“The conventional pigment paint is made in big facilities where they can make hundreds of gallons of paint,” he says. “At this moment, unless we go through the scale-up process, it is still expensive to produce at an academic lab.”

“We need to bring something different like, non-toxicity, cooling effect, ultralight weight, to the table that other conventional paints can’t.” Chanda says.

Licensing Opportunity

For more information about licensing this technology, please visit the Inorganic Paint Pigment for Vivid Plasmonic Color technology sheet.

Researcher’s Credentials

Chanda has joint appointments in UCF’s NanoScience Technology Center, Department of Physics and College of Optics and Photonics. He received his doctorate in photonics from the University of Toronto and worked as a postdoctoral fellow at the University of Illinois at Urbana-Champaign. He joined UCF in Fall 2012.

Here’s a link to and a citation for the paper,

Ultralight plasmonic structural color paint by Pablo Cencillo-Abad, Daniel Franklin, Pamela Mastranzo-Ortega, Javier Sanchez-Mondragon, and Debashis Chanda. Science Advances 8 Mar 2023 Vol 9, Issue 10 DOI: 10.1126/sciadv.adf7207

This paper is open access.

Here’s the researcher with one of ‘his butterflies’ (I may be reading a little too much into this but it looks like he’s uncomfortable having his photo taken but game to do it for work that he’s proud of),

Caption: Debashis Chanda, a professor in UCF’s NanoScience Technology Center, drew inspiration from butterflies to create the innovative new plasmonic paint, shown here applied to metal butterfly wings. Credit: University of Central Florida

Controlling neurons with light: no batteries or wires needed

Caption: Wireless and battery-free implant with advanced control over targeted neuron groups. Credit: Philipp Gutruf

This January 2, 2019 news item on ScienceDaily describes the object seen in the above and describes the problem it’s designed to solve,

University of Arizona biomedical engineering professor Philipp Gutruf is first author on the paper Fully implantable, optoelectronic systems for battery-free, multimodal operation in neuroscience research, published in Nature Electronics.

Optogenetics is a biological technique that uses light to turn specific neuron groups in the brain on or off. For example, researchers might use optogenetic stimulation to restore movement in case of paralysis or, in the future, to turn off the areas of the brain or spine that cause pain, eliminating the need for — and the increasing dependence on — opioids and other painkillers.

“We’re making these tools to understand how different parts of the brain work,” Gutruf said. “The advantage with optogenetics is that you have cell specificity: You can target specific groups of neurons and investigate their function and relation in the context of the whole brain.”

In optogenetics, researchers load specific neurons with proteins called opsins, which convert light to electrical potentials that make up the function of a neuron. When a researcher shines light on an area of the brain, it activates only the opsin-loaded neurons.

The first iterations of optogenetics involved sending light to the brain through optical fibers, which meant that test subjects were physically tethered to a control station. Researchers went on to develop a battery-free technique using wireless electronics, which meant subjects could move freely.

But these devices still came with their own limitations — they were bulky and often attached visibly outside the skull, they didn’t allow for precise control of the light’s frequency or intensity, and they could only stimulate one area of the brain at a time.

A Dec. 21, 2018 University of Azrizona news release (published Jan. 2, 2019 on EurekAlert), which originated the news item, discusses the work in more detail,

“With this research, we went two to three steps further,” Gutruf said. “We were able to implement digital control over intensity and frequency of the light being emitted, and the devices are very miniaturized, so they can be implanted under the scalp. We can also independently stimulate multiple places in the brain of the same subject, which also wasn’t possible before.”

The ability to control the light’s intensity is critical because it allows researchers to control exactly how much of the brain the light is affecting — the brighter the light, the farther it will reach. In addition, controlling the light’s intensity means controlling the heat generated by the light sources, and avoiding the accidental activation of neurons that are activated by heat.

The wireless, battery-free implants are powered by external oscillating magnetic fields, and, despite their advanced capabilities, are not significantly larger or heavier than past versions. In addition, a new antenna design has eliminated a problem faced by past versions of optogenetic devices, in which the strength of the signal being transmitted to the device varied depending on the angle of the brain: A subject would turn its head and the signal would weaken.

“This system has two antennas in one enclosure, which we switch the signal back and forth very rapidly so we can power the implant at any orientation,” Gutruf said. “In the future, this technique could provide battery-free implants that provide uninterrupted stimulation without the need to remove or replace the device, resulting in less invasive procedures than current pacemaker or stimulation techniques.”

Devices are implanted with a simple surgical procedure similar to surgeries in which humans are fitted with neurostimulators, or “brain pacemakers.” They cause no adverse effects to subjects, and their functionality doesn’t degrade in the body over time. This could have implications for medical devices like pacemakers, which currently need to be replaced every five to 15 years.

The paper also demonstrated that animals implanted with these devices can be safely imaged with computer tomography, or CT, and magnetic resonance imaging, or MRI, which allow for advanced insights into clinically relevant parameters such as the state of bone and tissue and the placement of the device.

This image of a combined MRI (magnetic resonance image) and CT (computer tomography) scan bookends, more or less, the picture of the device which headed this piece,

Combined image analysis with MRI and CT results superimposed on a 3D rendering of the animal implanted with the programmable bilateral multi µ-ILED device. Courtesy: University of Arizona

Here’s a link to and a citation for the paper,

Fully implantable optoelectronic systems for battery-free, multimodal operation in neuroscience research by Philipp Gutruf, Vaishnavi Krishnamurthi, Abraham Vázquez-Guardado, Zhaoqian Xie, Anthony Banks, Chun-Ju Su, Yeshou Xu, Chad R. Haney, Emily A. Waters, Irawati Kandela, Siddharth R. Krishnan, Tyler Ray, John P. Leshock, Yonggang Huang, Debashis Chanda, & John A. Rogers. Nature Electronics volume 1, pages652–660 (2018) DOI: https://doi.org/10.1038/s41928-018-0175-0 Published 13 December 2018

This paper is behind a paywall.

World’s first full-color, flexible thin-film reflective display: a step forward for camouflage?

Caption: Dr. Chanda used an iconic National Geographic photographic of an Afghan girl to demonstrate the color-changing abilities of the nanostructured reflective display developed by his team. Credit: University of Central Florida, used with permission from National Geographic

Caption: Dr. Chanda used an iconic National Geographic photographic of an Afghan girl to demonstrate the color-changing abilities of the nanostructured reflective display developed by his team. Credit: University of Central Florida, used with permission from National Geographic

This has gotten a lot of attention. A June 25, 2015 news item on Azonano describes a couple of possible applications,

Imagine a soldier who can change the color and pattern of his camouflage uniform from woodland green to desert tan at will. Or an office worker who could do the same with his necktie. Is someone at the wedding reception wearing the same dress as you? No problem – switch yours to a different color in the blink of an eye.

A June 24, 2015 University of Central Florida news release on EurekAlert, which originated the news item, provides some insight into the research along with some technical details,

Chanda’s [Professor Debashis Chanda] research was inspired by nature. Traditional displays like those on a mobile phone require a light source, filters and a glass plates. But animals like chameleons, octopuses and squids are born with thin, flexible, color-changing displays that don’t need a light source – their skin.

“All manmade displays – LCD, LED, CRT – are rigid, brittle and bulky. But you look at an octopus, they can create color on the skin itself covering a complex body contour, and it’s stretchable and flexible,” Chanda said. “That was the motivation: Can we take some inspiration from biology and create a skin-like display?”

As detailed in the cover article of the June issue of the journal Nature Communications, Chanda is able to change the color on an ultrathin nanostructured surface by applying voltage. The new method doesn’t need its own light source. Rather, it reflects the ambient light around it.

A thin liquid crystal layer is sandwiched over a metallic nanostructure shaped like a microscopic egg carton that absorbs some light wavelengths and reflects others. The colors reflected can be controlled by the voltage applied to the liquid crystal layer. The interaction between liquid crystal molecules and plasmon waves on the nanostructured metallic surface played the key role in generating the polarization-independent, full-color tunable display.

His method is groundbreaking. It’s a leap ahead of previous research that could produce only a limited color palette. And the display is only about few microns thick, compared to a 100-micron-thick human hair. Such an ultrathin display can be applied to flexible materials like plastics and synthetic fabrics.

The research has major implications for existing electronics like televisions, computers and mobile devices that have displays considered thin by today’s standards but monstrously bulky in comparison. But the potentially bigger impact could be whole new categories of displays that have never been thought of.

“Your camouflage, your clothing, your fashion items – all of that could change,” Chanda said. “Why would I need 50 shirts in my closet if I could change the color and pattern?”

Researchers used a simple and inexpensive nano-imprinting technique that can produce the reflective nanostructured surface over a large area.

“This is a cheap way of making displays on a flexible substrate with full-color generation,” Chanda said. “That’s a unique combination.”

Here’s a link to and a citation for the paper,

Polarization-independent actively tunable colour generation on imprinted plasmonic surfaces by Daniel Franklin, Yuan Chen, Abraham Vazquez-Guardado, Sushrut Modak, Javaneh Boroumand, Daming Xu, Shin-Tson Wu & Debashis Chanda. Nature Communications 6, Article number: 7337 doi:10.1038/ncomms8337 Published 11 June 2015

This paper is open access.