Friday, March 13, 2026

Heavy water expands energy potential of carbon nanotube yarns

University of Texas at Dallas

Twistron Yarns in Textile — image:
University of Texas at Dallas researchers embedded a twistron yarn array into a commercial textile, which when stretched simulates energy harvesting from human motion. Twistrons are carbon nanotube yarns that generate electricity when repeatedly stretched.
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Credit: University of Texas at Dallas

Researchers at The University of Texas at Dallas have developed a new electrolyte system that significantly boosts the energy-harvesting performance of twistrons, which are carbon nanotube yarns that generate electricity when repeatedly stretched.

The findings could aid in the manufacturing of intelligent textiles, such as fabrics used to make spacesuits, that would power wearable electronic devices or sensors by harvesting energy from human motion.

In a study published in the Feb. 24 print edition of ACS Nano, the UT Dallas scientists and their collaborators reported that replacing conventional water with heavy water in the neutral electrolyte solution that bathes the twistrons significantly increased energy output from the yarns.

Normal water comprises hydrogen and oxygen atoms. In heavy water, the hydrogen is replaced with deuterium, a form of hydrogen that contains an added neutron in its nucleus.

Compared to normal water, the heavy water‑based system delivered up to 2.5 times higher peak electrical power and 1.8 times more energy per stretching cycle at low frequencies, between 0.01 hertz (cycles per second) and 2 hertz. The energy conversion efficiency reached 9.5%, which is higher than any other previously reported twistron harvester operating in neutral electrolytes, said Dr. Mengmeng Zhang, corresponding author of the study and a research assistant professor and co-lead of the Alan G. MacDiarmid NanoTech Institute.

“Although this research focuses primarily on enhancing low-frequency energy harvesting — for example, from human movement or ocean waves — these deuterium-enhanced twistron harvesters also exhibit remarkable harvesting performance at high frequencies, from 2 hertz to 50 hertz,” Zhang said. “Potential higher-frequency uses might include harvesting electricity from rotating car wheels.”

Twistrons are spun yarns made from carbon nanotubes, hollow cylinders of carbon 10,000 times smaller in diameter than a human hair. Originally developed by a UT Dallas-led team and described in 2017 in the journal Science, twistrons were developed subsequently as three‑ply carbon nanotube yarns similar in structure to common textile fibers, which enables them to be integrated easily into fabrics.

Twistron performance is typically maximized when the twistrons are covered by strong acid electrolytes, but the corrosive nature of acid limits the fibers’ use in wearable or environmentally sensitive systems. Neutral water-based electrolyte solutions offer a safer alternative, but they are not as efficient.

“Our new heavy water‑based electrolyte system overcomes this challenge, providing a noncorrosive option that maintains high performance, particularly in low‑frequency environments such as human activity,” said Ishara Ekanayake, co-first author of the study and a chemistry doctoral student in the School of Natural Sciences and Mathematics (NSM).

“Using heavy water slows the movement of charged molecules and reduces or minimizes the self-discharging rate, so we can keep more charges on the carbon nanotubes. For energy harvesting, that’s a big benefit — more charges lead to better harvesting performance,” Ekanayake said.

To demonstrate practical use, the researchers embedded a twistron yarn array covered in a solid electrolyte gel into a commercial textile and stretched the material to simulate energy harvesting from human motion. The captured energy successfully powered wearable electronic devices.

“We can envision next‑generation wearable fabrics capable of continuously generating electricity from everyday movement to power phones, watches, tablets, laptops and other portable electronics,” Zhang said.

The team also demonstrated thermal‑energy harvesting by coupling electrolyte-coated twistron yarns to a polymer‑based artificial muscle that contracts when heated. As the muscle contracted, it stretched the twistron yarn to produce electricity, showing the technology’s potential for applications that involve environmental temperature changes.

The next step in the research will include identifying ways to optimize the deuterium-based electrolyte system.

Other UT Dallas researchers involved in the work are co-first author Dr. Wenting Cai, who was a visiting scientist from Texas State University; Dr. Shaoli Fang, co-corresponding author and associate research professor in the NanoTech Institute; Dr. Anvar Zakhidov, deputy director of the institute and professor of physics; Dr. Ali Aliev, research professor in the institute; Ashutosh Shrivastava PhD’25, postdoctoral researcher; Dr. Mihaela Stefan, professor and department head of chemistry and biochemistry; Dr. Michael Biewer, NSM associate dean of undergraduate education and professor of chemistry; and Dr. Ray Baughman, former director of the institute who died in 2025. Other authors are from Lintec of America Inc., and Huazhong University of Science and Technology.

The research was supported by the Office of Naval Research (grants ONR/STTR N68335-18-C-0368, ONR N00014-22-1-2569 and ONR N00014-23-1-2183) and The Welch Foundation.

This plied twistron yarn energy harvester, shown under an optical microscope, is about 200 micrometers in diameter, roughly twice the size of a human hair. University of Texas at Dallas researchers have developed a new electrolyte system that significantly boosts the energy-harvesting performance of twistrons, which are carbon nanotube yarns that generate electricity when repeatedly stretched.
Credit
University of Texas at Dallas

Journal

ACS Nano

DOI

10.1021/acsnano.5c18352

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

D2O-Enhanced Twistron Yarn Harvesters for Low-Frequency Mechanical Energy Harvesting

In a South Carolina swamp, researchers uncover secrets of firefly synchrony

University of Colorado at Boulder

Fireflies at night — image:
Fireflies twinkle against a backdrop of stars in Congaree National Park.
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Credit: Nolan Bonnie

In the middle of the old-growth forests of Congaree National Park in South Carolina, fireflies put on an other-worldly display every May. Thousands of male insects belonging to the species Photuris frontalis flash together at the same time and follow the exact same pattern—a synchronous light show you can see only in few places in the United States.

Scientists and nature lovers have long been fascinated by how such simple insects can work together in perfect harmony.

In a new study, engineers from the University of Colorado Boulder have uncovered the mathematical rules fireflies follow to sync up their flashes.

The team’s findings could one day lead to new designs for robots that move in swarms and could help scientists better understand other examples of synchrony in biology—such as neurons firing at the same time in the brain, or cells syncing to the body’s internal clock, also known as circadian rhythm.

“It’s magical,” said Orit Peleg, associate professor in the Department of Computer Science and the BioFrontiers Institute at CU Boulder. “At certain times of night, fireflies have a single rhythm for the entire group, and they’re very punctual.”

Peleg will present the team’s results Monday, March 16 at the American Physical Society’s 2026 Global Physics Summit in Denver. The researchers published their findings online ahead of peer review.

In the study, the researchers exposed individual male fireflies to a dim LED light—almost like an artificial version of a firefly.

If that light blinked faster than the males, the insects tended to speed up their flashing. If the light blinked slowly, the insects slowed down.

Think of it like an audience member in a crowded concert hall who is trying to join others clapping along to the beat.

“This research opens the door to discovering other examples of synchronization in nature that we haven’t seen yet,” said Owen Martin, the lead author of the research who earned his doctorate in computer science from CU Boulder in 2025.

Old patterns

The graduate student spent several summers at Congaree over the course of the experiment.

It’s a swampy area where cypress and tupelo trees hundreds of years old tower over the landscape. Martin remembers spending nights watching the twinkling light from fireflies reflect on the water of the park’s Cedar Creek.

“It makes me think of what that part of the Earth was like before people were there,” he said. “There is this strong sensation that everything is old.”

To study those ancient rhythms, Martin and Peleg set up a unique experiment: The team gently captured male fireflies one-by-one, then brought them into a tent that was completely shaded from all outside light.

Martin then sat in the pitch black and shined the LED at the males.

He explained that, under natural circumstances, fireflies tend to flash about once or twice every second. The group set its own LED to blink anywhere between once every second to once every 300 milliseconds.

The fireflies kept the beat.

In particular, the insects were most likely to change their own rhythm when the LED blinked almost at the same time as the fireflies, but just a hair off. If the LED blinked right before the firefly, the male often rushed its next flash to catch up to the light. If the LED blinked right after, the firefly waited a little longer to make its next flash.

If the LED was way off from the fireflies’ natural behavior, in contrast, they usually ignored it.

“For a whole season, I spent pretty much every night in the dark watching lights blink at a fixed frequency,” Martin said. “Then, occasionally, I’d get this magical experience where I’d see the firefly just start syncing with the light. I would wonder if I was just seeing things.”

Swarming robots

He wasn’t. Drawing on their observations, Martin and Peleg developed what mathematicians call a “phase-response curve” for the firefly flashes—essentially, a formula that describes how an outside light source drives fireflies to change their own flashing patterns.

The researchers noted that the team still has a lot of work to do to understand Congaree’s magical fireflies.

For a start, males in the wild rarely just see a single other source of light as they did in the team’s experiments. Instead, they’re usually in groups of dozens or more fireflies, all blinking at the same time.

Engineers can also learn a lot from what fireflies do in the wild. Study co-author Kaushik Jayaram, an engineer at Imperial College London, noted that future drones could communicate using visual signals, similar to fireflies.

“Peer-peer optical communication can be lower power and more secure, resulting more efficient swarming and robust aggregations despite requiring line-of-sight, adding a complementary capability to today’s miniature SWAP-constrained drones which largely rely on radio frequency-based approaches,” Jayaram said.

Peleg added that she envisions a future in which fleets of tiny robots work together to complete tasks without any central command.

“If you’re trying to get a lot of robots to push a large object, and they’re pushing at different times, then they’re going to struggle,” she said. “But if they’re all pushing at the same time, they’ll be a lot more successful.”

Long-exposure photo of a firefly swarm in Congaree.

Credit

Nolan Bonnie

How far will US seniors go for a doctor visit? Often much farther than expected

USC Dornsife researchers find willingness to travel for health care varies by income, mobility and location — insights that could impact the growth of telehealth as well as transportation planning.

University of Southern California

Older Americans are willing to travel far for medical care — sometimes much farther than policymakers and experts assume, according to researchers at the USC Dornsife College of Letters, Arts and Sciences.

Why it matters: As hospitals close in some areas, practices consolidate and telehealth expands, older adults may tolerate long trips for care — but not equally. The study suggests socioeconomic status affects willingness to travel.

What’s new: A study published recently in JAMA Network Open finds that many Americans age 65 and older are willing to travel more than an hour for routine or specialized medical care.

What happened: Researchers at the USC Dornsife Center for Economic and Social Research (CESR) surveyed a nationally representative group of older adults.

Questions centered on how long respondents currently travel for care and how much farther they would be willing to go before deciding to delay or skip an appointment.

Results: On average, respondents would tolerate about an hour or more of travel time, particularly for specialty care.

Growth of telehealth may be impacted by how willing patients are to take long trips for in-person care versus receiving remote clinical care. (Image source: iStock.)

For primary care visits, they would travel 68 minutes.
For a diagnostic test, such as an MRI, 113 minutes.
For a specialist visit, 128 minutes.

What they’re saying: “This shows older adults place a high value on access to care,” said Soeren Mattke, professor (research) of economics, director of the Brain Health Observatory at CESR and study senior author. “They are often willing to travel significant distances before delaying or forgoing care.”

Yes, but: The averages mask important differences.

Older adults in poorer health, those living in large metropolitan areas and those who had previously struggled with transportation were less willing to travel long durations.
In contrast, those with higher incomes, more education and reliable access to a car reported greater willingness to spend more time traveling.

Study first author Jeremy Burke, senior economist at CESR, said those gaps matter for health equity.

“If someone is already dealing with health challenges or transportation barriers, even modest increases in travel time can become a real obstacle,” Burke said. “Those are the patients most at risk of delaying care.”

The big picture: Health systems are consolidating, with some services moving into regional hubs rather than neighborhood clinics. Policymakers often debate how far is “too far” for patients to travel, especially for older adults.

This study suggests that distance alone isn’t the full story. The type of visit, transportation options and personal resources all shape decisions.

The findings also have implications for telehealth.

Virtual visits can reduce travel burdens, but they may not fully replace in-person care, especially for diagnostic tests or specialist consultations that require equipment or physical exams.
“Telehealth is an important tool, but it’s not a cure-all,” Mattke said. “We still need to think carefully about where services are located and how patients physically get there.”

What else? Transportation policy plays a role, too. Programs that offer ride services, improved public transit or partnerships with community organizations could make a meaningful difference for vulnerable seniors.

Between the lines: Older adults living in big cities were less willing to travel long durations.

This might boil down to traffic, parking and other travel complexities, which make even short drives feel burdensome.
But rural residents, who often already travel long distances for care, appeared more accepting of extended trips.

Bottom line: Many older Americans are willing to travel surprisingly long distances for medical care — but willingness depends on health, resources and access to transportation.

As care delivery models evolve, understanding those differences may help health systems and policymakers design services that better match patients’ needs and circumstances.

About the study

The findings are based on data from the Understanding America Study, a nationally representative internet panel administered by CESR. For this study, researchers surveyed a representative sample of 2,650 adults age 65 or older between April 23 and June 8, 2025, about their willingness to travel for primary care, specialty care and one-time diagnostic appointments.

In addition to Mattke and Burke, authors on the study include USC Dornsife researchers Tabasa Ozawa, Ying Liu and Wei Ye, all from the USC Brain Health Observatory based at USC Dornsife.

The study was funded by National Institute on Aging grants 1R01AG083189 and 1U01AG077280.