Coral reefs around the world are under threat from rising sea temperatures, ocean acidification, disease and overfishing, among other reasons.

Tracking signs of stress and ill health is difficult because corals — an animal host coexisting with algae, bacteria, viruses and fungi — are dynamic organisms that behave differently depending on what’s happening in their environment. Some scientists wonder if recording changes in coral movements over time could help with monitoring a coral reef’s health.

This is not always a straightforward task. Some coral species wave and pulse in the current, but others have rock-like skeletons and may have movements that are not visible to the human eye. A new study led by 91Ě˝»¨ researchers borrowed image-analysis methods from engineering to spot the minute movements of a stony coral.

The team April 8 in Scientific Reports.

“In mechanics, we have to be able to measure imperceptible deformations in materials and structures to understand how much load these systems are experiencing and to predict potential failures,” said co-senior author , a 91Ě˝»¨associate professor of aeronautics and astronautics. “We thought we could use these same analysis methods to study living systems, such as corals.”

First the researchers needed to find the right coral species to test.

“Our analysis method easily captures surface deformation when whatever we are imaging has texture on its surface. Smooth surfaces without textures, like polished metal and glass, don’t work as well,” said lead author , a 91Ě˝»¨doctoral student of aeronautics and astronautics. “Luckily, stony corals, such as Montipora capricornis, have unique patterns on their surfaces.”

To get started, the researchers set up a coral photo shoot. They took 200 images of the M. capricornis specimen in a tank at a rate of 30 photos per hour in both daytime and nighttime conditions, which were controlled using different lights.

“It was challenging to keep a sharp focus on the coral due to the way the light refracted off the glass tank,” Li said. “Also, we needed to pay particular attention to make sure the lighting conditions were consistent throughout the test.”

Once they had acquired the pictures, the researchers used two analysis methods to search for movement. Both methods compare subsequent images in a series to the first image, playing them like a flipbook to extract changes. From here, the team could measure parameters such as pixel velocity, what parts of the coral are moving, and whether something is being compressed or stretched. The researchers also further processed the photos to be able to pull out the different types of movements occurring across the coral.

Across all measurements, the researchers saw more activities happening under the nighttime conditions. The team also saw movement for both the tissue growing on the coral’s stony skeleton as well as the coral polyps, though the polyps had larger movements.

“Corals often feed more at night by expanding their polyps and using their tentacles to catch zooplankton prey, and here we are able to quantify these nocturnal movements,” said co-senior author , assistant professor of biological sciences at the University of Rhode Island. “This application of engineering techniques and analyses to assess subtle and dynamic movements can transform our understanding of coral behavior and physiology, which is critical as corals are under threat from multiple stressors.”

The team plans to expand this method to work on more coral species, including soft corals, which have much larger movements. Ultimately, the goal is to make this technique useful for determining potential changes in coral health under different circumstances.

“One investigation that should be considered is looking at how coral tissue motion changes upon exposure to pollutants generated by anthropogenic activities, such as chemical dispersants and oil,” Yang said. “Also this method could be used to monitor coral reefs by using satellite images or pictures taken by citizen scientists.”

, a 91Ě˝»¨assistant professor of chemical oceanography; and at Virginia Commonwealth University; and and at the Colorado School of Mines are also co-authors on this paper. This research was funded by the National Science Foundation, including a harnessing data revolution grant.

For more information, contact Yang at jkyang@aa.washington.edu, Li at sflee@uw.edu and Putnam at hputnam@uri.edu.

Coral reefs are disappearing at a rapid rate around the world. They’re threatened by human impacts at both local and global scales, and they’re facing dire predictions for the future.

But conservation and restoration efforts have been a challenge because corals — an animal host coexisting with algae, bacteria, viruses and fungi — act more like cities than individuals.

Now an interdisciplinary team of researchers from multiple institutions, including the 91Ě˝»¨, has received a two-year, $1.7 million National Science Foundation grant to study coral growth. The team includes , a 91Ě˝»¨associate professor of aeronautics and astronautics.

“This project is good example of how aerospace engineers, marine biologists, chemical engineers and computer scientists can work together,” Yang said. “Successful aerospace missions often rely on advanced materials, which can be used for other fields of studies. Likewise, materials — even living materials — in other fields can inspire the design of aerospace engineering materials.”

The researchers will study corals as though they are tiny manufacturing sites in the ocean. The team will focus on three unique characteristics of coral communities: the corals’ calcium carbonate skeletons, which provide 3D structures to shelter diverse sea life; corals’ ability to self-heal damage to their tissues; and the corals’ symbiotic relationships with other organisms.

At the UW, Yang’s group will 3D print scaffolds to guide coral growth and look into new techniques to measure how well the corals grow.

Collaborating with Yang are Judith Klein-Seetharaman at the Colorado School of Mines, Hollie Putnam of the University of Rhode Island, Lenore Cowen at Tufts University and Nastassja Lewinski at Virginia Commonwealth University.

“We are at a tipping point, where new research efforts could have a snowball effect in drastically increasing our understanding of corals,” said project lead Klein-Seetharaman, an associate professor of chemistry at Colorado School of Mines.

For more information, contact Yang at jkyang@aa.washington.edu.

Adapted from by the Colorado School of Mines.

91Ě˝»¨ researchers have developed a novel solution to change the feeling of impact when one thing hits another. It has potential for use in spacecraft, cars and beyond. Inspired by origami, the team created a paper model of a metamaterial that uses “folding creases” to soften impact forces and promote forces that relax stresses in the chain.

“If you were wearing a football helmet made of this material and something hit the helmet, you’d never feel that hit on your head. By the time the energy reaches you, it’s no longer pushing. It’s pulling,” said  , a 91Ě˝»¨associate professor of aeronautics and astronautics.

Read more in the related .

Space vehicles like are designed to be reusable. But this means that, like Olympic gymnasts hoping for a gold medal, they have to stick their landings.

Landing is stressful on a rocket’s legs because they must handle the force from the impact with the landing pad. One way to combat this is to build legs out of materials that absorb some of the force and soften the blow.

91Ě˝»¨ researchers have developed a novel solution to help reduce impact forces — for potential applications in spacecraft, cars and beyond. Inspired by the paper folding art of origami, the team created a paper model of a metamaterial that uses “folding creases” to soften impact forces and instead promote forces that relax stresses in the chain. The team May 24 in .

“If you were wearing a football helmet made of this material and something hit the helmet, you’d never feel that hit on your head. By the time the energy reaches you, it’s no longer pushing. It’s pulling,” said corresponding author , a 91Ě˝»¨associate professor of aeronautics and astronautics.

Yang and his team designed this new metamaterial to have the properties they wanted.

“Metamaterials are like Legos. You can make all types of structures by repeating a single type of building block, or unit cell as we call it,” he said. “Depending on how you design your unit cell, you can create a material with unique mechanical properties that are unprecedented in nature.”

The researchers turned to the art of origami to create this particular unit cell.

“Origami is great for realizing the unit cell,” said co-author , a 91Ě˝»¨aeronautics and astronautics doctoral student. “By changing where we introduce creases into flat materials, we can design materials that exhibit different degrees of stiffness when they fold and unfold. Here we’ve created a unit cell that softens the force it feels when someone pushes on it, and it accentuates the tension that follows as the cell returns to its normal shape.”

Just like origami, these unit cell prototypes are made out of paper. The researchers used a laser cutter to cut dotted lines into paper to designate where to fold. The team folded the paper along the lines to form a cylindrical structure, and then glued acrylic caps on either end to connect the cells into a long chain.

The researchers lined up 20 cells and connected one end to a device that pushed and set off a reaction throughout the chain. Using six GoPro cameras, the team tracked the initial compression wave and the following tension wave as the unit cells returned to normal.

The chain composed of the origami cells showed the counterintuitive wave motion: Even though the compressive pushing force from the device started the whole reaction, that force never made it to the other end of the chain. Instead, it was replaced by the tension force that started as the first unit cells returned to normal and propagated faster and faster down the chain. So the unit cells at the end of the chain only felt the tension force pulling them back.

“Impact is a problem we encounter on a daily basis, and our system provides a completely new approach to reducing its effects. For example, we’d like to use it to help both people and cars fare better in car accidents,” Yang said. “Right now it’s made out of paper, but we plan to make it out of a composite material. Ideally, we could optimize the material for each specific application.”

Additional co-authors are , a postdoc at the University of Pennsylvania who completed this research as a 91Ě˝»¨aeronautics and astronautics doctoral student; and at the University of Massachusetts; and at Bowdoin College. This research was funded by the National Science Foundation, the Office of Naval Research and the Washington Research Foundation.

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For more information, contact Yang at jkyang@aa.washington.edu.

Grant numbers: NSF CAREER-1553202, NSF DMS-1615037 and ONR N000141410388

91Ě˝»¨ engineers have turned tissue paper – similar to toilet tissue – into a new kind of wearable sensor that can detect a pulse, a blink of an eye and other human movement. The sensor is light, flexible and inexpensive, with potential applications in health care, entertainment and robotics.

The technology, described in a published in January in the journal Advanced Materials Technologies, shows that by tearing tissue paper that’s loaded with nanocomposites and breaking the paper’s fibers, the paper acts as a sensor. It can detect a heartbeat, finger force, finger movement, eyeball movement and more, said a 91Ě˝»¨associate professor of mechanical engineering and senior author of the research.

“The major innovation is a disposable wearable sensor made with cheap tissue paper,” said Chung. “When we break the specimen, it will work as a sensor.”

These small, Band Aid-sized sensors could have a variety of applications in various fields. For example, monitoring a person’s gait or the movement of their eyes can be used to inspect brain function or a game player’s actions. The sensor could track how a special-needs child walks in a home test, sparing the child the need for hospital visits. Or the sensors could be used in occupational therapy for seniors.

“They can use these sensors and after one-time use, they can be thrown away,” said Chung.

In their research, the scientists used paper similar to toilet tissue. The paper – nothing more than conventional paper towels – is then doused with carbon nanotube-laced water. Carbon nanotubes are tiny materials that create electrical conductivity. Each piece of tissue paper has both horizontal and vertical fibers, so when the paper is torn, the direction of the tear informs the sensor of what’s happened. To trace eye movement, they’re attached to a person’s reading glasses.

For now, the work has been contained to a laboratory, and researchers are hoping to find a suitable commercial use. A provisional patent was filed in December 2017.

The paper’s lead author is 91Ě˝»¨College of Engineering graduate student Jinyuan Zhang. Other co-authors include undergraduate student Cerwyn Chiew; mechanical engineering professors and ; aeronautics and astronautics professor and postdoctoral scholar , all of the UW; and graduate student Fabrice Fondjo and professor of Washington State University Vancouver.

The study was funded partially by Samsung Research America through the Think Tank Team Award.

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For more information, contact Chung at 206-543-4355 or jae71@uw.edu.