Scientists unveil how heat-loving enzyme could help improve plastic recycling

Researchers reveal cutinase combines a rigid core with a flexible active site, providing insights into heat resistance and plastic degradation

Tokyo University of Science

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The cutinase enzyme combines a rigid α/β-hydrolase core with a flexible lid loop near the active site. Structural comparison suggests that the lid loop undergoes conformational changes more readily than the rigid core.

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Credit: Professor Tatsuya Nishino from Tokyo University of Science, Japan

Among the various plastic recycling methods being explored, one promising approach is biological plastic recycling, also known as biorecycling, which utilizes enzymes or microorganisms to break down polymer molecules. One group of enzymes attracting attention is microbial cutinases. These enzymes are naturally produced by bacteria and fungi to degrade the waxy outer layer of plants, known as the cuticle. Because they can act on similar chemical bonds, they are considered promising for recycling poly(ethylene terephthalate) (PET), a plastic used in bottles and synthetic fibers.

However, applying these enzymes in industrial settings is not straightforward. PET is most efficiently degraded at temperatures around 70 °C, where it becomes more flexible and easier to process. At such high temperatures, enzymes must maintain a stable overall structure to avoid unfolding, while also retaining flexibility at their active site for molecular recognition and catalysis. This creates a design challenge, as structural rigidity and flexibility are often opposing properties.

To better understand this balance, a team of researchers led by Professor Tatsuya Nishino from the Department of Biological Science and Technology, Tokyo University of Science (TUS), Japan, along with Assistant Professor Sho Ito from the same department, and graduate researchers Mr. Ryohei Nojima (M.Sc., 2022) and Ms. Lirong Chen (M.Sc., 2024) from TUS, examined a heat-tolerant cutinase enzyme from the fungus Chaetomium thermophilum. The enzyme, known as CtCut, was analyzed under conditions relevant to high-temperature PET recycling to better understand how it maintains structural stability and catalytic potential. The study was published in Volume 16, Special Issue 4 of the journal Crystals on March 24, 2026.

“Plastic waste has become a severe problem in recent years, necessitating environmentally friendly recycling technologies. Thus, our aim was to contribute to the development of practical recycling technologies by clarifying the molecular basis of enzymes that function even under high-temperature conditions,” says Prof. Nishino.

For the study, the team created several versions of the enzyme. This included the wild-type (CtCutWT), which is the unmodified form, and a mutant version, CtCutS136A, in which the amino acid serine at position 136 is replaced with alanine.

They then determined the enzyme’s structure and assessed its thermal stability using differential scanning calorimetry, heating the protein from 30 °C to 100 °C to analyze how it absorbed heat.

Structurally, the enzyme adopts a highly stable α/β-hydrolase fold, a common architecture among cutinases. Covering the active site is a flexible lid loop that can open and close. In its closed state, the active site is less accessible, but upon binding a molecule, the lid changes shape to allow binding and catalysis.

Notably, a chloride ion was found near the active site even when no substrate was present, suggesting that the active site forms a positively charged electrostatic microenvironment that may facilitate ligand binding.

As the enzyme was heated, it showed a two-step unfolding process, with a gradual transition beginning at around 60 °C, followed by a second transition near 65–70 °C. This indicates that different parts of the enzyme lose stability at different temperatures, suggesting the presence of structurally distinct regions within the protein.

“Our findings suggest the possibility of functional division within the enzyme. We observed that the mobile region near the active site undergoes structural changes in response to ligand binding, and that thermal denaturation proceeds in multiple stages,” says Prof. Nishino.

These findings support the idea that enzymes designed for plastic degradation may require both a stable overall structure and a flexible active site. The rigid core provides the thermal stability needed to withstand industrial conditions, while the flexible lid loop may help the enzyme adapt to bound molecules.

By better understanding this balance between stability and flexibility, the study provides new insights into the function of heat-tolerant enzymes and how they can be improved.

“Our study may lead to the development of technologies for efficiently decomposing and recycling PET in the future by providing design guidelines for enzymes that possess both heat resistance and potential catalytic capabilities for polymer degradation. This may address the growing challenge of plastic waste and help realize a sustainable resource-recycling society,” concludes Prof. Nishino.

 

***

 

Reference       
DOI: 10.3390/cryst16040217

 

About The Tokyo University of Science
Tokyo University of Science (TUS) is a well-known and respected university, and the largest science-specialized private research university in Japan, with four campuses in central Tokyo and its suburbs and in Hokkaido. Established in 1881, the university has continually contributed to Japan's development in science through inculcating the love for science in researchers, technicians, and educators.

With a mission of “Creating science and technology for the harmonious development of nature, human beings, and society," TUS has undertaken a wide range of research from basic to applied science. TUS has embraced a multidisciplinary approach to research and undertaken intensive study in some of today's most vital fields. TUS is a meritocracy where the best in science is recognized and nurtured. It is the only private university in Japan that has produced a Nobel Prize winner and the only private university in Asia to produce Nobel Prize winners within the natural sciences field.

Website: https://www.tus.ac.jp/en/mediarelations/

 

About Professor Tatsuya Nishino from Tokyo University of Science
Dr. Tatsuya Nishino is a Professor at the Department of Biological Science and Technology, Tokyo University of Science, Japan. He earned his Doctor of Medicine degree from Osaka University in 2001. His research focuses on structural biology, particularly protein structure analysis using X-ray crystallography. His work includes the structural analysis of protein complexes to better understand molecular function. He has authored over 25 refereed papers with over 2,000 citations, contributing extensively to the field of molecular and structural biology.

Funding information
This work was partly supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI under Grant Numbers 20K06512 and 23K05671.

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Journal

Crystals

DOI

10.3390/cryst16040217 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Crystal Structures of a Thermophilic Cutinase from Chaetomium thermophilum Reveal Conformational Dynamics of the Catalytic Lid Loop

 

Millimeter-scale resolution in fiber-optic sensing: single-ended technique advances infrastructure monitoring

Researchers demonstrate that overcoming signal distortions enables record-breaking spatial resolution in single-access distributed fiber-optic sensing

Shibaura Institute of Technology

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Researchers demonstrate that operating at modulation frequencies close to Brillouin bandwidth and suppressing signal distortions allows BOCDR to achieve a world-record spatial resolution of 6 mm.

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Credit: Prof. Yosuke Mizuno from Yokohama National University, Japan https://ieeexplore.ieee.org/document/11278604

Distributed fiber-optic sensors are widely used to monitor temperature and strain in infrastructure, but their spatial resolution has long been limited. In a new study, researchers from Shibaura Institute of Technology and Yokohama National University, Japan, have demonstrated that operating near a previously avoided frequency regime and suppressing signal distortions allows reflection-based sensing to achieve a world-record spatial resolution of 6 mm among single-end-access configurations. This enables precise monitoring of temperature and strain in infrastructure.

Distributed fiber-optic sensing technologies play a crucial role in monitoring temperature and strain across large structures such as bridges, tunnels, pipelines, and buildings. Unlike conventional point sensors, distributed fiber-optic sensors provide continuous measurements along their entire length, allowing early detection of damage or abnormal conditions. However, one persistent challenge has been spatial resolution—the ability to pinpoint exactly where a change occurs. Improving resolution without complicating system design has remained a central goal in fiber-optic sensing research.

One promising technique, known as Brillouin optical correlation-domain reflectometry (BOCDR), enables distributed sensing using light injected from only one end of the fiber. This reflection-based configuration simplifies installation and allows measurements even if the fiber is damaged. BOCDR also offers higher spatial resolution than many other Brillouin-based methods. Yet, its performance has been constrained by a widely accepted assumption: operating near or beyond the Brillouin bandwidth, a frequency range intrinsic to the fiber, was believed to cause unstable signals and unreliable measurements. As a result, this operating regime has largely been avoided, limiting achievable resolution.

In a new study, a team of researchers led by Prof. Heeyoung Lee from Shibaura Institute of Technology, Japan, along with Prof. Yosuke Mizuno from Yokohama National University, Japan, and Mr. Keita Kikuchi from Shibaura Institute of Technology, Japan, experimentally investigated BOCDR operation at modulation frequencies close to the Brillouin bandwidth. Their findings were published in the Journal of Lightwave Technology on April 1, 2026.

“To verify whether the Brillouin bandwidth limitation was truly fundamental or simply not well understood, we examined the origin of the signal distortions and explored ways to control them. Notably, we discovered that this forbidden operating region can be used to significantly enhance spatial resolution,” says Prof. Lee.

The researchers observed that at higher modulation frequencies, periodic distortions appeared in the Brillouin gain spectrum, interfering with the accurate extraction of temperature and strain information. These distortions degrade the linear relationship between temperature/strain and the Brillouin frequency shift, particularly at high spatial resolution.

Rather than treating these distortions as unavoidable, the team carefully analyzed their physical origin and developed a signal-processing method to suppress them. By mapping the measured spectra into the frequency domain and selectively removing the modulation-induced components, they restored the stability and linearity of the Brillouin signal. This approach allowed BOCDR to operate reliably in a frequency regime that had previously been considered impractical.

Using this strategy, the researchers achieved distributed temperature and strain measurements with a spatial resolution of 6 mm—the highest ever reported for single-ended Brillouin sensing. In experimental demonstrations, the system successfully detected temperature changes confined to millimeter-scale fiber sections and resolved abrupt strain-like transitions introduced by short fiber segments with different optical properties.

The implications of this work extend beyond laboratory demonstrations. Aging infrastructure and increasing exposure to natural disasters demand sensing technologies capable of detecting subtle, highly localized changes before they escalate into serious damage to public safety and maintenance efficiency. Achieving millimeter-scale resolution using a simple, single-end-access fiber configuration makes practical deployment of fiber-optic sensors more feasible across civil engineering, energy, transportation, and robotics-related industries.

“Our study addresses the limitations of conventional sensors that miss the detection of subtle changes and proposes an approach that can be used for monitoring the integrity of optical waveguides, sensing the shape of flexible structures, and future robotic systems,” says Prof. Lee.

By overcoming a long-standing performance barrier, this study opens new pathways for distributed sensing systems that function like a “nerve network,” continuously monitoring the health of critical structures.

 

About Shibaura Institute of Technology (SIT), Japan

Shibaura Institute of Technology (SIT) is a private university with campuses in Tokyo and Saitama. Since the establishment of its predecessor, Tokyo Higher School of Industry and Commerce, in 1927, it has maintained “learning through practice” as its philosophy in the education of engineers. SIT was the only private science and engineering university selected for the Top Global University Project sponsored by the Ministry of Education, Culture, Sports, Science and Technology and had received support from the ministry for 10 years starting from the 2014 academic year. Its motto, “Nurturing engineers who learn from society and contribute to society,” reflects its mission of fostering scientists and engineers who can contribute to the sustainable growth of the world by exposing their over 9,500 students to culturally diverse environments, where they learn to cope, collaborate, and relate with fellow students from around the world.

Website: https://www.shibaura-it.ac.jp/en/

About Professor Heeyoung Lee from SIT, Japan

Dr. Heeyoung Lee is a Professor at the Graduate School of Engineering and Science, Shibaura Institute of Technology, Japan. She received a Ph.D. in Electrical and Electronic Engineering from the Institute of Science Tokyo, Japan, in 2019. Her research interests include fiber-optic sensing, polymer optics, and optoelectronics. She has been honored with multiple awards, including the NF Foundation R&D Encouragement Award 2019, the Kashiko Kodate Promotion and Nurturing of Female Researchers Contribution Award 2021, and the SCAT President’s Award 2025.

Funding Information

This work was supported in part by JSPS KAKENHI under Grant 21H04555 and Grant 22K14272 and by research grants from the Telecommunications Advancement Foundation, and in part by Asahipen Hikari Foundation.

 

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Journal

Journal of Lightwave Technology

DOI

10.1109/JLT.2025.3640608 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

BOCDR achieving 6-mm spatial resolution at modulation frequencies close to Brillouin bandwidth

Article Publication Date

19-Apr-2026

 

Industrial chemicals delay recovery of the ozone layer

Ozone protection under pressure

Swiss Federal Laboratories for Materials Science and Technology (Empa)

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The Jungfraujoch high alpine research station is located at 3,580 meters above sea level on a mountain saddle in the central Swiss Alps.

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Credit: Empa

Although ozone-depleting chemicals such as carbon tetrachloride (CCl₄) or certain chlorofluorocarbons (CFCs) are no longer used in refrigerators and foams, they continue to serve as feedstocks in industrial processes for the production of modern refrigerants and plastics. Until now, these so-called feedstock chemicals have flown under the radar of international agreements because the quantities produced and leakage rates were significantly underestimated.

Working with international research groups, Empa researchers have now used global measurements to show that during the production and processing of these substances, approximately three to four percent escapes into the atmosphere through leaks. Furthermore, their use has increased significantly in recent decades. In a study published in Nature Communications, they have now calculated that, as a result, the ozone layer is likely to recover about seven years later than previously assumed – unless emissions are reduced. “These substances are not only ozone-depleting but also highly harmful to the climate. Lower emissions would thus benefit both the ozone layer and the climate,” says Stefan Reimann, an atmospheric scientist at Empa and lead author of the study.

Measurements show higher emissions

When the Montreal Protocol was negotiated in the 1980s and later strengthened, it led to a global ban on ozone-depleting substances in everyday products. Feedstock chemicals, however, were exempt from this ban. At the time, industry assumed that only about 0.5 percent of the quantities produced would escape into the atmosphere and that the use of these substances would decline in the long term. “But this assessment has not been accurate anymore for quite some time,” says Reimann. “Feedstock chemicals are now being released in increased quantities during production, transport, and further processing, and the volumes currently being produced are significantly larger than was assumed 30 years ago.”

These new findings are based on global atmospheric measurements from international networks such as the Advanced Global Atmospheric Gases Experiment (AGAGE), which includes the Empa research station on the Jungfraujoch. Since many ozone-depleting substances remain in the atmosphere for decades, their concentrations allow conclusions to be drawn about global emissions. “We measure the concentrations of these substances in the atmosphere. Based on their lifetimes, we can calculate how much they should actually be decreasing. If they aren’t, emissions must still be occurring,” explains Martin Vollmer, an Empa researcher and co-author of the study.

A comparison of these measurements with the production figures officially reported by individual countries shows that today, an average of three to four percent of the feedstock produced enters the atmosphere – several times the originally assumed values. For carbon tetrachloride, which is particularly harmful to the ozone layer, emission rates are even above four percent.

Why usage is increasing

However, emissions are rising not only because of higher production losses, but also because the overall use of feedstock chemicals is increasing – by about 160 percent since the year 2000. Some of these feedstocks were initially used to produce hydrofluorocarbons (HFCs), which were introduced as refrigerant substitutes following the ban on CFCs. Since these substitutes later proved to be potent greenhouse gases, they are now being phased out under the so-called Kigali Amendment. They are increasingly being replaced by hydrofluoroolefins (HFOs), which have little impact on the climate but whose production again relies heavily on ozone-depleting feedstock chemicals.

Added to this is a rapidly growing use in the polymer industry – for example, in the production of fluoropolymers such as Teflon (PTFE) or polyvinylidene fluoride (PVDF), an important material in lithium-ion batteries for electric cars. “The quantities of feedstock are not decreasing but will continue to grow, at least in the coming years,” says Reimann.

Both the ozone layer and the climate are affected

Based on these developments, the international research team calculated various future scenarios. They compared, for example, the originally assumed, very low emission rates with the values measured today from the use of feedstock chemicals. The established benchmark from 1980, when global ozone depletion was first observed, serves as a reference. Until now, it was assumed that this original state of the ozone layer would be reached again around the year 2066. However, the new calculations show that if feedstock emissions remain at current levels, this timeline will shift by about seven years. The stratospheric ozone layer would therefore not fully recover until around 2073. The margin of uncertainty for this estimate ranges from six to eleven years.

However, the feedstock chemicals released not only damage the ozone layer but also act as powerful greenhouse gases. If nothing changes, these additional climate-damaging emissions will reach around 300 million metric tons of CO₂ equivalents per year by mid-century – comparable to the current annual CO₂ emissions of a country like England or France. Reducing these emissions would therefore have a dual benefit.

Whether these emissions will be reduced in the future through binding emission limits or a targeted restriction of particularly problematic substances is, according to Stefan Reimann, ultimately a political decision. Even though the Montreal Protocol continues to be regarded as one of the greatest successes of international environmental policy, it should be regularly reviewed and, if necessary, adapted in light of new scientific findings. “The Montreal Protocol was successful because science, politics, and industry worked closely together. Such cooperation is crucial again today to address new challenges,” says Reimann.

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Journal

Nature Communications

DOI

10.1038/s41467-026-70533-w 

Method of Research

Computational simulation/modeling

Article Title

Continuing Industrial Emissions Are Delaying the Recovery of the Stratospheric Ozone Layer

Article Publication Date

16-Apr-2026

A regulatory loophole could delay ozone recovery by years

Scientists say an exception in the Montreal Protocol for the use of ozone-depleting feedstocks could set the ozone recovery back seven years.

Massachusetts Institute of Technology

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Often hailed as the most successful international environmental agreement of all time, the 1987 Montreal Protocol continues to successfully phase out the global production of chemicals that were creating a growing hole in the ozone layer, causing skin cancer and other adverse health effects.

MIT-led studies have since shown the subsequent reduction in ozone-depleting substances is helping stratospheric ozone to recover. (It could return to 1980 levels by as early as 2040, according to some estimates.) But the Montreal Protocol made an exception in its rules for the use of ozone-depleting substances as feedstocks in the production of other materials. That’s because it was thought that only a small amount — just 0.5 percent — of the ozone-depleting substances used for this purpose would leak into the atmosphere.

In recent years, however, scientists have observed more ozone-depleting substances in the atmosphere than expected, and have increased their estimates of leakage from feedstocks.

Now an international group of scientists, including researchers from MIT, has calculated the impact of different feedstock leakage rates on the ozone’s fragile recovery. They find the higher leakage rates, if not addressed by the Montreal Protocol, could delay ozone recovery by about seven years.

“We’ve realized in the last few years that these feedstock chemicals are a bug in the system,” says author Susan Solomon, the Lee and Geraldine Martin Professor of Environmental Studies and Chemistry, who was part of the original research team that linked the chemicals to the ozone hole. “Production of ozone-depleting substances has pretty much ceased around the world except for this one use, which is when you have a chemical you convert into something else.”

The paper, which will be published in Nature Communications, is the first to comprehensively quantify the impact of leaked feedstocks, which are currently used to make plastics and nonstick chemicals. They are also used to make substitute chemicals for the ones regulated under the Montreal Protocol. The researchers say it shows the importance of curbing use and preventing leakage of such feedstocks, especially as the production of their end products, like plastic, is projected to grow.

“We’ve gotten to the point where, if we want the protocol to be as successful in the future as it has been in the past, the parties really need to think about how to tighten up the emissions of these industrial processes,” says first author Stefan Reimann of the Swiss Federal Laboratories for Materials Science and Technology.

“To me, it’s only fair, because so many other things have already been completely discontinued. So why should this exemption exist if it’s going to be damaging?” says Solomon.

Joining Reimann on the paper are his colleagues Martin K. Vollmer and Lukas Emmenegger; Luke Western and Susan Solomon of the MIT Center for Sustainability Science and Strategy and the Department of Earth, Atmospheric and Planetary Sciences; David Sherry of Nolan-Sherry and Associates Ltd; Megan Lickley of Georgetown University; Lambert Kuijpers of the A/gent Consultancy b.v.; Stephen A. Montzka and John Daniel of the National Oceanic and Atmospheric Administration; Matthew Rigby of the University of Bristol; Guus J.M. Velders of Utrecht University; Qing Liang of the NASA Goddard Space Flight Center; and Sunyoung Park of Kyungpook National University.

Repairing the ozone

In 1985, scientists discovered a growing hole in the ozone layer over Antarctica that was allowing more of the sun’s harmful ultraviolet radiation to reach Earth’s surface. The following year, researchers including Solomon traveled to Antarctica and discovered the cause of the ozone deterioration: a class of chemicals called chlorofluorocarbons, or CFCs, which were then used in refrigeration, air conditioning, and aerosols.

The revelations led to the Montreal Protocol, an international treaty involving 197 countries and the European Union restricting the use of CFCs. The subsequent decision to exempt the use of ozone-depleting substances for use as feedstocks was based partially on industry estimates of how much of their feedstocks leaked.

“It was thought that the emissions of these substances as a feedstock were minor compared to things like refrigerants and foams,” Western says. “It was also believed that leakage from these sources was minor — around half a percent of what went in — because people would essentially be leaking their profits if their feedstocks were released into the atmosphere.”

Unfortunately, some of those assumptions are no longer true. Western and Reimann are part of the Advanced Global Atmospheric Gases Experiment (AGAGE), a global monitoring network co-founded by Ronald Prinn, MIT’s TEPCO Professor of Atmospheric Science. AGAGE monitors emissions of ozone-depleting substances around the world, and in recent years researchers have revised their estimates of feedstock leakage upwards, to about 3.6 percent. For some chemicals, the number was even higher.

In the new paper, the researchers estimated a 3.6 percent feedstock leakage as the baseline for most chemicals. They compared that with a scenario where 0.5 percent of feedstocks are leaked from 2025 onward and a scenario with zero feedstock-related emissions. The researchers also looked at production trends between 2014 and 2024 to project how much of each specific ozone-depleting chemical would be used as feedstock between 2025 and 2100.

The analysis shows that until 2050, total ozone-depleting chemical emissions decrease in all scenarios as rising feedstock emissions are offset by declining uses enforced by the Montreal Protocol. In the scenario with continued 3.6 percent leakage, however, emissions level off around 2045, and total emissions only decrease by 50 percent overall by 2100.

The researchers then evaluated the impact of feedstock-related emissions on stratospheric ozone depletion. In the scenario where feedstock leakage is 0.5 percent, the ozone returns to its 1980 status by 2066. In the scenario with zero feedstock leakage, the ozone reclaims its 1980 health in 2065. But in the baseline scenario, the recovery is delayed about seven years, to 2073.

“This paper sends an important message that these emissions are too high and we have to find a way to reduce them,” Reimann says. “Either that means no longer using these substances as feedstocks, swapping out chemicals, or reducing the leakage emissions when they are used.”

A global response

Solomon is confident industries will be able to adjust to the latest findings.

“There are a lot of innovators in the chemical industry,” Solomon says. “They make new chemicals and improve chemicals for a living. It’s true they can perhaps get too entrenched with certain chemicals, but it doesn’t happen that often. Actually, they’re usually quite willing to consider alternatives. There are thousands of other chemicals that could be used instead, so why not switch? That’s been the attitude.”

Solomon says the fact that AGAGE can detect the impact of feedstock emissions is a testament to the progress the world has made in reducing emissions from other sources up to this point. She believes raising awareness of the feedstock problem is the first step. 

“This isn't the first time that the AGAGE Network has made measurements that have allowed the world to see we need to do a little better here or there,” Western says. “Often, it’s just a mistake. Sometimes all it takes is making people more aware of these things to tighten up some processes.”

Members of the Montreal Protocol meet every year. In those meetings, they split into working groups around different topics. Feedstock emissions are already one of those topics, so participants will review the evidence together. Typically, they release a statement about mitigation strategies if needed.

“We wanted to raise the warning flag that something is wrong here,” Reimann says. “We could reduce the period of ozone depletion by years. It might not sound like a long time, but if you could count the skin cancer cases you’d avoid in that time, it would seem quite significant.”

The work was supported in part by the National Science Foundation, NASA, the Swiss Federal Office for the Environment, the VoLo Foundation, the United Kingdom Natural Environment Research Council, and the Korea Meteorological Administration Research and Development Program.

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Journal

Nature Communications

Article Title

“Continuing industrial emissions are delaying the recovery of the stratospheric ozone layer”

 

Slime-like robots from sci-fi become reality: SNU researchers develop next-generation artificial muscle that dynamically reconfigures and self-heals

World’s first demonstration of ‘phase-transitional ferrofluid electrodes’ bridging liquid and solid states/Recoverable and reusable after failure, presenting a ‘sustainable’ paradigm for soft robotics

Seoul National University College of Engineering

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Figure 1. Operation and applications of a reconfigurable next-generation artificial muscle device and physical properties of the phase-transitional ferrofluid
(1) A reconfigurable artificial muscle device capable of performing multiple functions through repeated phase transitions and magnetic responsiveness of slime-like ferrofluid electrodes.
(2) Schematic illustration and physical characteristics of the phase-transitional ferrofluid, demonstrating reversible solid-liquid phase transitions and the integration of high elasticity and low viscosity within a single material.
 

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Credit: © Science Advances, originally published in Science Advances

Breaking away from conventional robots that perform only predefined functions once fabricated, researchers have developed a next-generation artificial muscle that can change its shape in real time, recover from damage, and even be reused.

 

Seoul National University College of Engineering announced that a joint research team led by Prof. Jeong-Yun Sun (Department of Materials Science and Engineering) and Prof. Ho-Young Kim (Department of Mechanical Engineering), with Yun Hyeok Lee, Seungwon Moon, and Min-gyu Lee as first and co-first authors, has developed a new type of dielectric elastomer actuator (DEA) using a phase-transitional ferrofluid (PTF) that behaves as a solid at room temperature but becomes fluid-like and highly flexible when exposed to external stimuli such as heat or magnetic fields.

 

The study was published on March 21 in Science Advances, a leading international journal published by the American Association for the Advancement of Science (AAAS).

 

Dielectric elastomer actuators (DEAs) are soft transducers that convert electrical energy into mechanical motion and are often referred to as artificial muscles because of their ability to move rapidly and precisely like human muscles.

 

Artificial muscles based on dielectric elastomers are soft and lightweight, and have increasingly been applied in daily lives and industrial settings, including haptic vibration components in smart and wearable devices, as well as soft robotic grippers capable of safely handling delicate objects such as fruits or fragile components.

 

However, once the electrode pattern is designed and printed, its shape becomes permanently fixed, meaning that such systems can only perform a single, predefined motion.

 

As a result, whenever a robot needs to grasp objects of different shapes or adapt to new environments, both industry and academia have been required to redesign and fabricate entirely new electrode patterns from scratch. This has led to significant manufacturing costs and inefficiencies, and has remained a major barrier to the commercialization of versatile, multifunctional soft robots.

 

To overcome these limitations, Lee et al. developed a next-generation soft gel actuator capable of dynamically reconfiguring electrode patterns in real time, performing new functions as needed, and recovering even after mechanical damage or electrical failure.

 

The newly developed phase-transitional ferrofluid (PTF) electrode can dynamically split and merge into three-dimensional configurations. Even after fabrication, its shape and position can be freely adjusted, significantly expanding the functional capabilities of soft robots beyond fixed, predesigned motions. In addition, the electrode’s self-healing and recyclability enhance the sustainability of robotic systems.

 

A key achievement of this study lies in the seamless integration of advanced materials engineering, through the precise combination of nanoparticles and polymers, with a fully functional mechanical system. Materials engineering enabled the development of a stable yet flexible phase-transitional electrode, while mechanical engineering demonstrated how the material operates during actuation, reconfiguration, and recovery.

 

As a result, a single soft actuator can now perform entirely different roles depending on the situation, transforming conventional soft robots into adaptive systems capable of altering their functions in response to changing environments and tasks.

 

○ Key Features of the Phase-Transitional Ferrofluid (PTF) Electrode

 

1. Real-Time Functional Reconfiguration (Reconfiguration):

Even during operation of the artificial muscle, the electrode can be melted into a liquid state (sol) and repositioned using a magnetic field, or split into two or more parts. Beyond simple two-dimensional planar movement, it can be spatially partitioned in 3D architectures to perform different functions, or autonomously bridge severed circuits via 3D out-of-plane configurations, thereby achieving an advanced level of functional freedom. This enables a single robot to perform entirely different motions, such as bending and expansion, as if learning them in real time.

 

2. Self-Healing and Recovery Capability (Self-healing & Recovery):

The system remains functional even if the electrode is severed by sharp objects or if electrical breakdown occurs due to high voltage. By converting the electrode near the damaged region into a liquid state, the broken circuit can be reconnected, or the system can be reconfigured to bypass only the damaged area, thereby fully restoring the robot’s functionality.

 

3. Environmentally Friendly Reusability (Recyclable):

After a device has completed its task or reached the end of its lifespan, the electrode alone can be extracted in liquid form, stored, and later injected into a new device for reuse. Lee et al. demonstrated that even after multiple reuse cycles, the system maintains a high recovery rate of approximately 91% along with consistent performance.

 

This research represents a transformative step toward ending the era of passive and disposable machines, introducing instead a new class of sustainable, adaptive systems capable of continuous regeneration and self-reconfiguration. The technology has broad potential applications, ranging from highly advanced artificial muscles capable of replicating complex, multi-degree-of-freedom human movements, to next-generation form-factor displays that can dynamically alter shape and information in real time, and smart robots that can repair themselves while operating in extreme industrial environments involving electrical failure or physical damage.

 

Furthermore, by enabling electrodes to be extracted and reused rather than discarding entire devices at the end of their lifespan, the study proposes a fundamentally new, environmentally sustainable resource circulation paradigm that could significantly impact future soft robotics and next-generation electronics industries.

 

Prof. Jeong-Yun Sun stated, “This study represents a breakthrough in transforming traditionally static and passive electrodes into ‘living, programmable elements’ through innovations in particle and polymer design. This self-healing and shape-reconfigurable electrode technology will serve as a key foundation for sustainable next-generation soft robotics.”

 

Prof. Ho-Young Kim added, “From a mechanical engineering perspective, achieving high degrees of freedom in soft robots, similar to human muscles, requires structural flexibility. Through interdisciplinary integration with materials engineering, we demonstrated that a single robotic structure can generate virtually limitless modes of motion.”

 

Yun Hyeok Lee, who received his PhD from SNU’s Department of Materials Science and Engineering, is currently conducting postdoctoral research at the Massachusetts Institute of Technology (MIT), focusing on the development of new platform materials using nanoparticles, DNA, and polymers.

 

Seungwon Moon, a PhD candidate in the same department, is currently working on the development of high thermal conductivity polymer materials for semiconductor and electronic device applications.

 

Min-gyu Lee received his PhD from SNU and is now working at Samsung Electronics’ Semiconductor Research Center, where he is involved in the development of next-generation high-bandwidth memory (HBM).

 

This research was conducted with support from the Ministry of Science and ICT and the National Research Foundation of Korea through the Mid-career Researcher Program, the Future Promising Fusion Technology Pioneer Program, and the Global Leader Grants.

 

 

Figure 2. Functional expansion of reconfigurable electrodes and artificial muscle devices using phase-transitional ferrofluid

(1) Three-dimensional reconfigurable electrodes enabled by PTF, allowing the realization of next-generation artificial muscle devices and freely reconfigurable displays.

(2) Self-healing and repair of artificial muscles through PTF reconfiguration, enabling continued operation after electrode damage and allowing recovery and reuse to enhance device sustainability.

Credit

© Science Advances, originally published in Science Advances

Self-healable PTF electrode for DEAs [VIDEO]

□ Introduction to the SNU College of Engineering

 

Seoul National University (SNU) founded in 1946 is the first national university in South Korea. The College of Engineering at SNU has worked tirelessly to achieve its goal of ‘fostering leaders for global industry and society.’ In 12 departments, 323 internationally recognized full-time professors lead the development of cutting-edge technology in South Korea and serving as a driving force for international development.

 

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Journal

Science Advances

DOI

10.1126/sciadv.aeb7409 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

A reconfigurable dielectric elastomer actuator via phase-transitional ferrofluid enables sustainable operation