The original headline for the University of Oxford press release was “Batteries for miniature bio-integrated devices and robotics” but it’s not clear to me what they mean by robotics (soft robots? robotic prostheses? something else?).
University of Oxford researchers have made a significant step towards realising miniature, soft batteries for use in a variety of biomedical applications, including the defibrillation and pacing of heart tissues. The work has been published today [October 25, 2024] in the journal Nature Chemical Engineering.
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An October 28, 2024 University of Oxford press release (also on EurekAlert but published October 25, 2024), which originated the lightly edited news item and posting on EurekAlert, provides more technical detail about this advance, Note: Links have been removed,
The development of tiny smart devices, smaller than a few cubic millimeters, demands equally small power sources. For minimally invasive biomedical devices that interact with biological tissues, these power sources must be fabricated from soft materials. Ideally, these should also have features such as high capacity, biocompatibility and biodegradability, triggerable activation, and the ability to be controlled remotely. To date, there has been no battery that can fulfil these requirements all at once.
To address these requirements, researchers from the University of Oxford’s Department of Chemistry and Department of Pharmacology have developed a miniature, soft lithium-ion battery constructed from biocompatible hydrogel droplets. Surfactant-supported assembly (assembly aided by soap-like molecules), a technique reported by the same group last year in the journal Nature (DOI: 10.1038/s41586-023-06295-y), is used to connect three microscale droplets of 10 nanolitres volume. Different lithium-ion particles contained in each of the two ends then generate the output energy.
‘Our droplet battery is light-activated, rechargeable, and biodegradable after use. To date, it is the smallest hydrogel lithium-ion battery and has a superior energy density’ said Dr Yujia Zhang (Department of Chemistry, University of Oxford), the lead researcher for the study and a starting Assistant Professor at the École Polytechnique Fédérale de Lausanne. ‘We used the droplet battery to power the movement of charged molecules between synthetic cells and to control the beating and defibrillation of mouse hearts. By including magnetic particles to control movement, the battery can also function as a mobile energy carrier.’
Proof-of-concept heart treatments were carried out in the laboratory of Professor Ming Lei (Department of Pharmacology), a senior electrophysiologist in cardiac arrhythmias. He said: ‘Cardiac arrhythmia is a leading cause of death worldwide. Our proof-of-concept application in animal models demonstrates an exciting new avenue of wireless and biodegradable devices for the management of arrhythmias.’
Professor Hagan Bayley (Department of Chemistry), the research group leader for the study, said: ‘The tiny soft lithium-ion battery is the most sophisticated in a series of microscale power packs developed by Dr Zhang and points to a fantastic future for biocompatible electronic devices that can operate under physiological conditions.’
The researchers have filed a patent application through Oxford University Innovation. They envisage that the tiny versatile battery, particularly relevant to small-scale robots for bioapplications, will open up new possibilities in various areas including clinical medicine.
Here’s a link to and a citation for the paper,
A microscale soft lithium-ion battery for tissue stimulation by Yujia Zhang, Tianyi Sun, Xingyun Yang, Linna Zhou, Cheryl M. J. Tan, Ming Lei & Hagan Bayley. Nature Chemical Engineering volume 1, pages 691–701 (2024) DOI: https://doi.org/10.1038/s44286-024-00136-z Published online: 25 October 2024 Issue Date: November 2024
This paper is open access.
Now, I want to highlight a few items from the paper’s introduction, Note: Links have been removed,
The miniaturization of electronic devices is a burgeoning area of research1,2,3. Therefore, the development of tiny batteries to power these devices is of critical importance, and techniques such as three-dimensional (3D) printing4,5,6 and micro-origami assembly7 [emphases mine] are beginning to have an impact. For minimally invasive applications in biomedicine, batteries are also preferred to be soft, biocompatible and biodegradable, with additional functionality and responsiveness, such as triggerable activation and remote-controlled mobility8. However, at present, such a multifunctional microscale soft battery is not available. Although hydrogel-based lithium-ion (Li-ion) batteries demonstrate some of these features9,10,11,12, none currently exhibits microscale fabrication of the battery architecture, in terms of self-assembled integration of hydrogel-based cathode, separator and anode at the submillimeter level. Manual assembly of precrosslinked compartments11 or multistep deposition and crosslinking4 is necessary to avoid the mixing of materials from different compartments at the pregel (liquid) state or during the gelation process. This limitation not only makes it difficult to shrink hydrogel-based functional architectures but also hinders the implementation of high-density energy storage.
Toward that end, Zhang et al. have reported a miniaturized ionic power source by depositing lipid-supported networks of nanoliter hydrogel droplets13. The power source mimics the electrical eel [emphasis mine] by using internal ion gradients to generate ionic current14, and can induce neuronal modulation. However, the ionic power source has several limitations [emphasis mine] that should be addressed. First, the stored salt gradient produces less power than conventional Li-ion batteries, and the device cannot be fully recharged. Second, activation of the power source relies on temperature-triggered gelation and oil for buffer exchange, which is a demanding requirement. Third, the functionality of the power source is limited to the generation of ionic output, leaving the full versatility of synthetic tissues unexploited15,16,17. Last, but not least, while the power source can modulate the activity of neural microtissues, organ-level stimulation necessitates a higher and more stable output performance in physiological environments18.
Here, we present a miniature, soft, rechargeable Li-ion droplet battery (LiDB) made by depositing self-assembling [emphasis mine], nanoliter, lipid-supported, silk hydrogel droplets. The tiny hydrogel compartmentalization produces a superior energy density. The battery is switched on by ultraviolet (UV) light, which crosslinks the hydrogel and breaks the lipid barrier between droplets. The droplets are soft, biocompatible and biodegradable. The LiDBs can power charge molecule translocation between synthetic cells, defibrillate mouse hearts with ventricular arrhythmias and pace heart rhythms. Further, the LiDB can be translocated from one site to another magnetically.
This team has integrated a number of cutting edge (I think you can still call them that) techniques such as 3D printing and origami along with inspiration from electric eels (biomimicry) for using light as a power source. .Finally, there’s self-assembly or, as it’s sometimes known, bottom-up engineering, just like nature.
This work still needs to be tested in human clinical trials but taking that into account: Bravo to the researchers!
The ideal material for interfacing electronics with living tissue is soft, stretchable, and just as water-loving as the tissue itself–in short, a hydrogel. Semiconductors, the key materials for bioelectronics such as pacemakers, biosensors, and drug delivery devices, on the other hand, are rigid, brittle, and water-hating, impossible to dissolve in the way hydrogels have traditionally been built. Scientists have now solved this challenge that has long stymied researchers, reimagining the process of creating hydrogels to build a powerful semiconductor in hydrogel form. The result is a bluish gel that flutters like a sea jelly in water but retains the immense semiconductive ability needed to transmit information between living tissue and machine.
A paper published today in Science from the UChicago Pritzker School of Molecular Engineering (PME) has solved this challenge that has long stymied researchers, reimagining the process of creating hydrogels to build a powerful semiconductor in hydrogel form. Led by Asst. Prof. Sihong Wang’s research group, the result is a bluish gel that flutters like a sea jelly in water but retains the immense semiconductive ability needed to transmit information between living tissue and machine.
The material demonstrated tissue-level moduli as soft as 81 kPa, stretchability of 150% strain, and charge-carrier mobility up to 1.4 cm2 V-1 s-1. This means their material—both semiconductor and hydrogel at the same time—ticks all the boxes for an ideal bioelectronic interface.
“When making implantable bioelectronic devices, one challenge you must address is to make a device with tissue-like mechanical properties,” said Yahao Dai, the first author of the new paper. “That way, when it gets directly interfaced with the tissue, they can deform together and also form a very intimate bio-interface.”
Although the paper mainly focused on the challenges facing implanted medical devices such as biochemical sensors and pacemakers, Dai said the material also has many potential non-surgical applications, like better readings off the skin or improved care for wounds.
“It has very soft mechanical properties and a large degree of hydration similar to living tissue,” said UChicago PME Asst. Prof. Sihong Wang. “Hydrogel is also very porous, so it allows the efficient diffusion transport of different kinds of nutrition and chemicals. All these traits combine to make hydrogel probably the most useful material for tissue engineering and drug delivery.”
‘Let’s change our perspective’
The typical way of making a hydrogel is to take a material, dissolve it in water, and add the gelation chemicals to puff the new liquid into a gel form. Some materials simply dissolve in water, others require researchers to tinker and chemically modify the process, but the core mechanism is the same: No water, no hydrogel.
Semiconductors, however, don’t normally dissolve in water. Rather than find new, time-consuming means of trying to force the process, the UChicago PME team re-examined the question.
“We started to think, ‘Okay, let’s change our perspective,’ and we came up with a solvent exchange process,” Dai said.
Instead of dissolving the semiconductors in water, they dissolved them in an organic solvent that is miscible with water. They then prepared a gel from the dissolved semiconductors and hydrogel precursors. Their gel initially was an organogel, not a hydrogel.
“To eventually turn it into a hydrogel, we then immersed the whole material system into the water to let the organic solvent dissolve out and let the water come in,” Dai said.
An important benefit of such a solvent-exchange-based method is its broad applicability to different types of polymer semiconductors with different functions.
‘One plus one is greater than two’
The hydrogel semiconductor, which the team has patented and is commercializing through UChicago’s Polsky Center for Entrepreneurship and Innovation, is not merging a semiconductor with a hydrogel. It’s one material that is both semiconductor and hydrogel at the same time.
“It’s just one piece that has both semiconducting properties and hydrogel design, meaning that this whole piece is just like any other hydrogel,” Wang said.
Unlike any other hydrogel, however, the new material actually improved biological functions in two areas, creating better results than either hydrogel or semiconductor could accomplish on their own.
First, having a very soft material bond directly with tissue reduces the immune responses and inflammation typically triggered when a medical device is implanted.
Second, because hydrogels are so porous, the new material enables elevated biosensing response and stronger photo-modulation effects. With biomolecules being able to diffuse into the film to have volumetric interactions, the interaction sites for biomarkers-under-detection are significantly increased, which gives rise to higher sensitivity. Besides sensing, the responses to light for therapeutic functions at tissue surfaces also get increased from the more efficient transport of redox-active species. This benefits functions such as light-operated pacemakers or wound dressing that can be more efficiently heated with a flick of light to help speed healing.
“It’s a ‘one plus one is greater than two’ kind of combination,” Wang joked.
Researchers in the lab of UChicago Pritzker School of Engineering Asst. Prof. Sihong Wang (right), including PhD student Yahao Dai (left), have developed a hydrogel that retains the semiconductive ability needed to transmit information between living tissue and machine, which can be used both in implantable medical devices and non-surgical applications. (Photo by John Zich)
Here’s a link to and a citation for the paper,
Soft hydrogel semiconductors with augmented biointeractive functions by Yahao Dai, Shinya Wai, Pengju Li, Naisong Shan, Zhiqiang Cao, Yang Li, Yunfei Wang, Youdi Liu, Wei Liu, Kan Tang, Yuzi Liu, Muchuan Hua, Songsong Li, Nan Li, Shivani Chatterji, H. Christopher Fry, Sean Lee, Cheng Zhang, Max Weires, Sean Sutyak, Jiuyun Shi, Chenhui Zhu, Jie Xu, Xiaodan Gu, Bozhi Tian, and Sihong Wang. Science 24 Oct 2024 Vol 386, Issue 6720 pp. 431-439 DOI: 10.1126/science.adp9314
First, thank you to anyone who’s dropped by to read any of my posts. Second, I didn’t quite catch up on my backlog in what was then the new year (2024) despite my promises. (sigh) I will try to publish my drafts in a more timely fashion but I start this coming year as I did 2024 with a backlog of two to three months. This may be my new normal.
As for now, here’s an overview of FrogHeart’s 2024. The posts that follow are loosely organized under a heading but many of them could fit under other headings as well. After my informal review, there’s some material on foretelling the future as depicted in an exhibition, “Oracles, Omens and Answers,” at the Bodleian Libraries, University of Oxford.
Human enhancement: prosthetics, robotics, and more
Within a year or two of starting this blog I created a tag ‘machine/flesh’ to organize information about a number of converging technologies such as robotics, brain implants, and prosthetics that could alter our concepts of what it means to be human. The larger category of human enhancement functions in much the same way also allowing a greater range of topics to be covered.
Here are some of the 2024 human enhancement and/or machine/flesh stories on this blog,
As for anyone who’s curious about hydrogels, there’s this from an October 20, 2016 article by D.C.Demetre for ScienceBeta, Note: A link has been removed,
Hydrogels, materials that can absorb and retain large quantities of water, could revolutionise medicine. Our bodies contain up to 60% water, but hydrogels can hold up to 90%.
It is this similarity to human tissue that has led researchers to examine if these materials could be used to improve the treatment of a range of medical conditions including heart disease and cancer.
These days hydrogels can be found in many everyday products, from disposable nappies and soft contact lenses to plant-water crystals. But the history of hydrogels for medical applications started in the 1960s.
Scientists developed artificial materials with the ambitious goal of using them in permanent contact applications , ones that are implanted in the body permanently.
For anyone who wants a more technical explanation, there’s the Hydrogel entry on Wikipedia.
Science education and citizen science
Where science education is concerned I’m seeing some innovative approaches to teaching science, which can include citizen science. As for citizen science (also known as, participatory science) I’ve been noticing heightened interest at all age levels.
It’s been another year where artificial intelligence (AI) has absorbed a lot of energy from nearly everyone. I’m highlighting the more unusual AI stories I’ve stumbled across,
As you can see, I’ve tucked in two tangentially related stories, one which references a neuromorphic computing story ((see my Neuromorphic engineering category or search for ‘memristors’ in the blog search engine for more on brain-like computing topics) and the other is intellectual property. There are many, many more stories on these topics
Art/science (or art/sci or sciart)
It’s a bit of a surprise to see how many art/sci stories were published here this year, although some might be better described as art/tech stories.
There may be more 2024 art/sci stories but the list was getting long. In addition to searching for art/sci on the blog search engine, you may want to try data sonification too.
Moving off planet to outer space
This is not a big interest of mine but there were a few stories,
I expect to be delighted, horrified, thrilled, and left shaking my head by science stories in 2025. Year after year the world of science reveals a world of wonder.
More mundanely, I can state with some confidence that my commentary (mentioned in the future-oriented subsection of my 2023 review and 2024 look forward) on Quantum Potential, a 2023 report from the Council of Canadian Academies, will be published early in this new year as I’ve almost finished writing it.
Some questions are hard to answer and always have been. Does my beloved love me back? Should my country go to war? Who stole my goats?
Questions like these have been asked of diviners around the world throughout history – and still are today. From astrology and tarot to reading entrails, divination comes in a wide variety of forms.
Yet they all address the same human needs. They promise to tame uncertainty, help us make decisions or simply satisfy our desire to understand.
Anthropologists and historians like us study divination because it sheds light on the fears and anxieties of particular cultures, many of which are universal. Our new exhibition at Oxford’s Bodleian Library, Oracles, Omens & Answers, explores these issues by showcasing divination techniques from around the world.
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1. Spider divination
In Cameroon, Mambila spider divination (ŋgam dù) addresses difficult questions to spiders or land crabs that live in holes in the ground.
Asking the spiders a question involves covering their hole with a broken pot and placing a stick, a stone and cards made from leaves around it. The diviner then asks a question in a yes or no format while tapping the enclosure to encourage the spider or crab to emerge. The stick and stone represent yes or no, while the leaf cards, which are specially incised with certain meanings, offer further clarification.
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2. Palmistry
Reading people’s palms (palmistry) is well known as a fairground amusement, but serious forms of this divination technique exist in many cultures. The practice of reading the hands to gather insights into a person’s character and future was used in many ancient cultures across Asia and Europe.
In some traditions, the shape and depth of the lines on the palm are richest in meaning. In others, the size of the hands and fingers are also considered. In some Indian traditions, special marks and symbols appearing on the palm also provide insights.
Palmistry experienced a huge resurgence in 19th-century England and America, just as the science of fingerprints was being developed. If you could identify someone from their fingerprints, it seemed plausible to read their personality from their hands.
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3. Bibliomancy
If you want a quick answer to a difficult question, you could try bibliomancy. Historically, this DIY [do-it-yourself] divining technique was performed with whatever important books were on hand.
Throughout Europe, the works of Homer or Virgil were used. In Iran, it was often the Divan of Hafiz, a collection of Persian poetry. In Christian, Muslim and Jewish traditions, holy texts have often been used, though not without controversy.
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4. Astrology
Astrology exists in almost every culture around the world. As far back as ancient Babylon, astrologers have interpreted the heavens to discover hidden truths and predict the future.
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5. Calendrical divination
Calendars have long been used to divine the future and establish the best times to perform certain activities. In many countries, almanacs still advise auspicious and inauspicious days for tasks ranging from getting a haircut to starting a new business deal.
In Indonesia, Hindu almanacs called pawukon [calendar] explain how different weeks are ruled by different local deities. The characteristics of the deities mean that some weeks are better than others for activities like marriage ceremonies.
6 December 2024 – 27 April 2025 ST Lee Gallery, Weston Library
The Bodleian Libraries’ new exhibition, Oracles, Omens and Answers, will explore the many ways in which people have sought answers in the face of the unknown across time and cultures. From astrology and palm reading to weather and public health forecasting, the exhibition demonstrates the ubiquity of divination practices, and humanity’s universal desire to tame uncertainty, diagnose present problems, and predict future outcomes.
Through plagues, wars and political turmoil, divination, or the practice of seeking knowledge of the future or the unknown, has remained an integral part of society. Historically, royals and politicians would consult with diviners to guide decision-making and incite action. People have continued to seek comfort and guidance through divination in uncertain times — the COVID-19 pandemic saw a rise in apps enabling users to generate astrological charts or read the Yijing [I Ching], alongside a growth in horoscope and tarot communities on social media such as ‘WitchTok’. Many aspects of our lives are now dictated by algorithmic predictions, from e-health platforms to digital advertising. Scientific forecasters as well as doctors, detectives, and therapists have taken over many of the societal roles once held by diviners. Yet the predictions of today’s experts are not immune to criticism, nor can they answer all our questions.
Curated by Dr Michelle Aroney, whose research focuses on early modern science and religion, and Professor David Zeitlyn, an expert in the anthropology of divination, the exhibition will take a historical-anthropological approach to methods of prophecy, prediction and forecasting, covering a broad range of divination methods, including astrology, tarot, necromancy, and spider divination.
Dating back as far as ancient Mesopotamia, the exhibition will show us that the same kinds of questions have been asked of specialist practitioners from around the world throughout history. What is the best treatment for this illness? Does my loved one love me back? When will this pandemic end? Through materials from the archives of the Bodleian Libraries alongside other collections in Oxford, the exhibition demonstrates just how universally human it is to seek answers to difficult questions.
Highlights of the exhibition include: oracle bones from Shang Dynasty China (ca. 1250-1050 BCE); an Egyptian celestial globe dating to around 1318; a 16th-century armillary sphere from Flanders, once used by astrologers to place the planets in the sky in relation to the Zodiac; a nineteenth-century illuminated Javanese almanac; and the autobiography of astrologer Joan Quigley, who worked with Nancy and Ronald Reagan in the White House for seven years. The casebooks of astrologer-physicians in 16th- and 17th-century England also offer rare insights into the questions asked by clients across the social spectrum, about their health, personal lives, and business ventures, and in some cases the actions taken by them in response.
The exhibition also explores divination which involves the interpretation of patterns or clues in natural things, with the idea that natural bodies contain hidden clues that can be decrypted. Some diviners inspect the entrails of sacrificed animals (known as ‘extispicy’), as evidenced by an ancient Mesopotamian cuneiform tablet describing the observation of patterns in the guts of birds. Others use human bodies, with palm readers interpreting characters and fortunes etched in their clients’ hands. A sketch of Oscar Wilde’s palms – which his palm reader believed indicated “a great love of detail…extraordinary brain power and profound scholarship” – shows the revival of palmistry’s popularity in 19th century Britain.
The exhibition will also feature a case study of spider divination practised by the Mambila people of Cameroon and Nigeria, which is the research specialism of curator Professor David Zeitlyn, himself a Ŋgam dù diviner. This process uses burrowing spiders or land crabs to arrange marked leaf cards into a pattern, which is read by the diviner. The display will demonstrate the methods involved in this process and the way in which its results are interpreted by the card readers. African basket divination has also been observed through anthropological research, where diviners receive answers to their questions in the form of the configurations of thirty plus items after they have been tossed in the basket.
Dr Michelle Aroney and Professor David Zeitlyn, co-curators of the exhibition, say:
Every day we confront the limits of our own knowledge when it comes to the enigmas of the past and present and the uncertainties of the future. Across history and around the world, humans have used various techniques that promise to unveil the concealed, disclosing insights that offer answers to private or shared dilemmas and help to make decisions. Whether a diviner uses spiders or tarot cards, what matters is whether the answers they offer are meaningful and helpful to their clients. What is fun or entertainment for one person is deadly serious for another.
Richard Ovenden, Bodley’s [a nickname? Bodleian Libraries were founded by Sir Thomas Bodley] Librarian, said:
People have tried to find ways of predicting the future for as long as we have had recorded history. This exhibition examines and illustrates how across time and culture, people manage the uncertainty of everyday life in their own way. We hope that through the extraordinary exhibits, and the scholarship that brings them together, visitors to the show will appreciate the long history of people seeking answers to life’s biggest questions, and how people have approached it in their own unique way.
The exhibition will be accompanied by the book Divinations, Oracles & Omens, edited by Michelle Aroney and David Zeitlyn, which will be published by Bodleian Library Publishing on 5 December 2024.
Courtesy: Bodleian Libraries, University of Oxford
I’m not sure why the preceding image is used to illustrate the exhibition webpage but I find it quite interesting. Should you be in Oxford, UK and lucky enough to visit the exhibition, there are a few more details on the Oracles, Omens and Answers event webpage, Note: There are 26 Bodleian Libraries at Oxford and the exhibition is being held in the Weston Library,
EXHIBITION
Oracles, Omens and Answers
6 December 2024 – 27 April 2025
ST Lee Gallery, Weston Library
Free admission, no ticket required
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Note: This exhibition includes a large continuous projection of spider divination practice, including images of the spiders in action.
Exhibition tours
Oracles, Omens and Answers exhibition tours are available on selected Wednesdays and Saturdays from 1–1.45pm and are open to all.
This seems like a good idea especially for those of us who live in areas where wildfires have become commonplace, from an August 22, 2024 news item on ScienceDaily,
As climate change creates hotter, drier conditions, we are seeing longer fire seasons with larger, more frequent wildfires. In recent years, catastrophic wildfires have destroyed homes and infrastructure, caused devastating losses in lives and livelihoods of people living in affected areas, and damaged wildland resources and the economy. We need new solutions to fight wildfires and protect areas from damage.
Researchers at Stanford have developed a water-enhancing gel that could be sprayed on homes and critical infrastructure to help keep them from burning during wildfires [emphasis mine]. The research, published Aug. 21 [2024] in Advanced Materials, shows that the new gels last longer and are significantly more effective [emphasis mine] than existing commercial gels.
“Under typical wildfire conditions, current water-enhancing gels dry out in 45 minutes,” said Eric Appel, associate professor of materials science and engineering in the School of Engineering, who is senior author of the paper. “We’ve developed a gel that would have a broader application window – you can spray it further in advance of the fire and still get the benefit of the protection – and it will work better when the fire comes.
Long-lasting protection
Water-enhancing gels are made of super-absorbent polymers – similar to the absorbent powder found in disposable diapers. Mixed with water and sprayed on a building, they swell into a gelatinous substance that clings to the outside of the structure, creating a thick, wet shield. But the conditions in the vicinity of a wildfire are extremely dry – temperatures can be near 100 degrees, with high winds and zero percent humidity – and even water locked in a gel evaporates fairly quickly.
In the gel designed by Appel and his colleagues, the water is just the first layer of protection. In addition to a cellulose-based polymer, the gel contains silica particles, which get left behind when the gels are subjected to heat. “We have discovered a unique phenomenon where a soft, squishy hydrogel seamlessly transitions into a robust aerogel shield under heat, offering enhanced and long-lasting wildfire protection. This environmentally conscious breakthrough surpasses current commercial solutions, offering a superior and scalable defense against wildfires,” said the lead author of the study, Changxin “Lyla” Dong.
“When the water boils off and all of the cellulose burns off, we’re left with the silica particles assembled into a foam,” Appel said. “That foam is highly insulative and ends up scattering all of the heat, completely protecting the substrate underneath it.”
The silica forms an aerogel – a solid, porous structure that is a particularly good insulator. Similar silica aerogels are used in space applications because they are extremely lightweight and can prevent most methods of heat transfer.
The researchers tested several formulations of their new gel by applying them to pieces of plywood and exposing them to direct flame from a gas hand-torch, which burns at a considerably higher temperature than a wildfire. Their most effective formulation lasted for more than 7 minutes before the board began to char. When they tested a commercially available water-enhancing gel in the same way, it protected the plywood for less than 90 seconds.
“Traditional gels don’t work once they dry out,” Appel said. “Our materials form this silica aerogel when exposed to fire that continues to protect the treated substrates after all the water has evaporated. These materials can be easily washed away once the fire is gone.”
A serendipitous discovery
The new gels build off of Appel’s previous wildfire prevention work. In 2019, Appel and his colleagues used these same gels as a vehicle to hold wildland fire retardants on vegetation for months at a time. The formulation was intended to help prevent ignition in wildfire-prone areas.
“We’ve been working with this platform for years now,” Appel said. “This new development was somewhat serendipitous – we were wondering how these gels would behave on their own, so we just smushed some on a piece of wood and exposed it to flames from a torch we had laying around the lab. What we observed was this super cool outcome where the gels puffed up into an aerogel foam.”
After that initial success, it took several years of additional engineering to optimize the formulation. It is now stable in storage, easily sprayable with standard equipment, and adheres well to all kinds of surfaces. The gels are made of nontoxic components that have already been approved for use by the U.S. Forest Service, and the researchers conducted studies to show that they are easily broken down by soil microbes.
“They’re safe for both people and the environment,” Appel said. “There may need to be additional optimization, but my hope is that we can do pilot-scale application and evaluation of these gels so we can use them to help protect critical infrastructure when a fire comes through.”
Matthew Davidson, a Research Associate with the University of Colorado demonstrates a 3D printed biomaterials for use inside the body including bandages that could be put on a beating human heart in Jason Burdick’s lab. (Photo by Casey A. Cass/University of Colorado)
Soft, strong, and flexible, that’s what you need if you’re going to apply a bandage to a heart and according to an August 1, 2024 news item on phys.org, researchers have developed a promising new material,
In the quest to develop life-like materials to replace and repair human body parts, scientists face a formidable challenge: Real tissues are often both strong and stretchable and vary in shape and size.
A CU [Colorado University] Boulder-led team, in collaboration with researchers at the University of Pennsylvania, has taken a critical step toward cracking that code. They’ve developed a new way to 3D print material that is at once elastic enough to withstand a heart’s persistent beating, tough enough to endure the crushing load placed on joints, and easily shapable to fit a patient’s unique defects.
Better yet, it sticks easily to wet tissue.
Their breakthrough, described in the Aug. 2 [2024] edition of the journal Science, helps pave the way toward a new generation of biomaterials, from internal bandages that deliver drugs directly to the heart to cartilage patches and needle-free sutures.
“Cardiac and cartilage tissues are similar in that they have very limited capacity to repair themselves. When they’re damaged, there is no turning back,” said senior author Jason Burdick, a professor of chemical and biological engineering at CU Boulder’s BioFrontiers Institute. “By developing new, more resilient materials to enhance that repair process, we can have a big impact on patients.”
Worm ‘blobs’ as inspiration
Historically, biomedical devices have been created via molding or casting, techniques which work well for mass production of identical implants but aren’t practical when it comes to personalizing those implants for specific patients. In recent years, 3D printing has opened a world of new possibilities for medical applications by allowing researchers to make materials in many shapes and structures.
Unlike typical printers, which simply place ink on paper, 3D printers deposit layer after layer of plastics, metals or even living cells to create multidimensional objects.
One specific material, known as a hydrogel (the stuff that contact lenses are made of), has been a favorite prospect for fabricating artificial tissues, organs and implants.
But getting these from the lab to the clinic has been tough because traditional 3D-printed hydrogels tend to either break when stretched, crack under pressure or are too stiff to mold around tissues.
“Imagine if you had a rigid plastic adhered to your heart. It wouldn’t deform as your heart beats,” said Burdick. “It would just fracture.”
To achieve both strength and elasticity within 3D printed hydrogels, Burdick and his colleagues took a cue from worms, which repeatedly tangle and untangle themselves around one another in three-dimensional “worm blobs” that have both solid and liquid-like properties. Previous research has shown that incorporating similarly intertwined chains of molecules, known as “entanglements,” can make them tougher.
Their new printing method, known as CLEAR (for Continuous-curing after Light Exposure Aided by Redox initiation), follows a series of steps to entangle long molecules inside 3D-printed materials much like those intertwined worms.
When the team stretched and weight-loaded those materials in the lab (one researcher even ran over a sample with her bike) they found them to be exponentially tougher than materials printed with a standard method of 3D printing known as Digital Light Processing (DLP). Better yet: They also conformed and stuck to animal tissues and organs.
“We can now 3D print adhesive materials that are strong enough to mechanically support tissue,” said co-first author Matt Davidson, a research associate in the Burdick Lab. “We have never been able to do that before.”
Revolutionizing care
Burdick imagines a day when such 3D-printed materials could be used to repair defects in hearts, deliver tissue-regenerating drugs directly to organs or cartilage, restrain bulging discs or even stitch people up in the operating room without inflicting tissue damage like a needle and suture can.
His lab has filed for a provisional patent and plans to launch more studies soon to better understand how tissues react to the presence of such materials.
But the team stresses that their new method could have impacts far beyond medicine—in research and manufacturing too. For instance, their method eliminates the need for additional energy to cure, or harden, parts, making the 3D printing process more environmentally friendly.
“This is a simple 3D processing method that people could ultimately use in their own academic labs as well as in industry to improve the mechanical properties of materials for a wide variety of applications,” said first author Abhishek Dhand, a researcher in the Burdick Lab and doctoral candidate in the Department of Bioengineering at the University of Pennsylvania. “It solves a big problem for 3D printing.”
Here’s a link to and a citation for the paper,
Additive manufacturing of highly entangled polymer networks by Abhishek P. Dhand, Matthew D. Davidson, Hannah M. Zlotnick, Thomas J. Kolibaba, Jason P. Killgore, and Jason A. Burdick. Science 1 Aug 2024 Vol 385, Issue 6708 pp. 566-572 DOI: 10.1126/science.adn692
A fascinating new use for hyaluronic acid (usually discussed in relation to cosmetic wrinkle-reduction) has been found according to a November 1, 2023 news item on ScienceDaily.
In a recent publication in the journal Nature, researchers from the Institute of Basic Science (IBS) in South Korea have made significant strides in biomaterial technology and rehabilitation medicine. They’ve developed a novel approach to healing muscle injury by employing “injectable tissue prosthesis” in the form of conductive hydrogels and combining it with a robot-assisted rehabilitation system.
Let’s imagine you are swimming in the ocean. A giant shark approaches and bites a huge chunk of meat out of your thigh, resulting in a complete loss of motor/sensor function in your leg.
If left untreated, such severe muscle damage would result in permanent loss of function and disability.
How on Earth will you be able to recover from this kind of injury?
Traditional rehabilitation methods for these kinds of muscle injuries have long sought an efficient closed-loop gait rehabilitation system that merges lightweight exoskeletons and wearable/implantable devices.
Such assistive prosthetic system is required to aid the patients through the process of recovering sensory and motor functions linked to nerve and muscle damage.
Unfortunately, the mechanical properties and rigid nature of existing electronic materials render them incompatible with soft tissues.
This leads to friction and potential inflammation, stalling patient rehabilitation.
To overcome these limitations, the IBS researchers turned to a material commonly used as a wrinkle-smoothing filler, called hyaluronic acid.
Using this substance [hyaluronic acid], an injectable hydrogel was developed for “tissue prostheses”, which can temporarily fill the gap of the missing muscle/nerve tissues while it regenerates. The injectable nature of this material gives it a significant advantage over traditional bioelectronic devices, which are unsuitable for narrow, deep, or small areas, and necessitate invasive surgeries.
Thanks to its highly “tissue-like” properties, this hydrogel seamlessly interfaces with biological tissues and can be easily administered to hard-to-reach body areas without surgery. The reversible and irreversible crosslinks within the hydrogel adapt to high shear stress during injection, ensuring excellent mechanical stability. This hydrogel also incorporates gold nanoparticles, which gives it decent electrical properties. Its conductive nature allows for the effective transmission of electrophysiological signals between the two ends of injured tissues. In addition, the hydrogel is biodegrdable, meaning that the patients do not need to get surgery again.
With mechanical properties akin to natural tissues, exceptional tissue adhesion, and injectable characteristics, researchers believe this material offers a novel approach to rehabilitation.
Next, the researchers put this novel idea to the test in rodent models. To simulate volumetric muscle loss injury, a large chunk of muscle has been removed from the hind legs of these animals. By injecting the hydrogel and implanting the two kinds of stretchable tissue-interfacing devices for electrical sensing and stimulation, the researchers were able to improve the gait in the “injured” rodents. The hydrogel prosthetics were combined with robot assistance, guided by muscle electromyography signals. Together, the two helped enhance the animal’s gait without nerve stimulation. Furthermore, muscle tissue regeneration was effectively improved over the long term after the conductive hydrogel was used to fill muscle damage.
The injectable conductive hydrogel developed in this study excels in electrophysiological signal recording and stimulation performance, offering the potential to expand its applications. It presents a fresh approach to the field of bioelectronic devices and holds promise as a soft tissue prosthesis for rehabilitation support.
Emphasizing the significance of the research, Professor SHIN Mikyung notes, “We’ve created an injectable, mechanically tough, and electrically conductive soft tissue prosthesis ideal for addressing severe muscle damage requiring neuromusculoskeletal rehabilitation. The development of this injectable hydrogel, utilizing a novel cross-linking method, is a notable achievement. We believe it will be applicable not only in muscles and peripheral nerves but also in various organs like the brain and heart.”
Professor SON Donghee added, “In this study, the closed-loop gait rehabilitation system entailing tough injectable hydrogel and stretchable and self-healing sensors could significantly enhance the rehabilitation prospects for patients with neurological and musculoskeletal challenges. It could also play a vital role in precise diagnosis and treatment across various organs in the human body.”
The research team is currently pursuing further studies to develop new materials for nerve and muscle tissue regeneration that can be implanted in a minimally invasive manner. They are also exploring the potential for recovery in various tissue damages through the injection of the conductive hydrogel, eliminating the need for open surgery.
Here’s a link to and a citation for the paper,
Injectable tissue prosthesis for instantaneous closed-loop rehabilitation by Subin Jin, Heewon Choi, Duhwan Seong, Chang-Lim You, Jong-Sun Kang, Seunghyok Rho, Won Bo Lee, Donghee Son & Mikyung Shin. Nature volume 623, pages 58–65 (2023) DOI: https://doi.org/10.1038/s41586-023-06628-x Published: 01 November 2023 Issue Date: 02 November 2023
Who doesn’t love a panda? It looks like someone is drawing on the armband with their fingers but the lines look a lot finer, more like a stylus was used.
Caption: When a person draws a panda on this touch-responsive armband that’s worn on their forearm (bottom right of photo), it shows up on a computer. Credit: Adapted from ACS Nano 2023, DOI: 10.1021/acsnano.2c12612
It’s time to roll up your sleeves for the next advance in wearable technology — a fabric armband that’s actually a touch pad. In ACS [American Chemical Society] Nano, researchers say they have devised a way to make playing video games, sketching cartoons and signing documents easier. Their proof-of-concept silk armband turns a person’s forearm into a keyboard or sketchpad. The three-layer, touch-responsive material interprets what a user draws or types and converts it into images on a computer.
Computer trackpads and electronic signature-capture devices seem to be everywhere, but they aren’t as widely used in wearables. Researchers have suggested making flexible touch-responsive panels from clear, electrically conductive hydrogels, but these substances are sticky, making them hard to write on and irritating to the skin. So, Xueji Zhang, Lijun Qu, Mingwei Tian and colleagues wanted to incorporate a similar hydrogel into a comfortable fabric sleeve for drawing or playing games on a computer.
The researchers sandwiched a pressure-sensitive hydrogel between layers of knit silk. The top piece was coated in graphene nanosheets to make the fabric electrically conductive. Attaching the sensing panel to electrodes and a data collection system produced a pressure-responsive pad with real-time, rapid sensing when a finger slid over it, writing numbers and letters. The device was then incorporated into an arm-length silk sleeve with a touch-responsive area on the forearm. In experiments, a user controlled the direction of blocks in a computer game and sketched colorful cartoons in a computer drawing program from the armband. The researchers say that their proof-of-concept wearable touch panel could inspire the next generation of flexible keyboards and wearable sketchpads.
By combining seaweed and graphene, scientists have been able to create sensors that can be worn like a ‘second skin’ and outperform other similar biosensors, according to a March 3, 2023 news item on ScienceDaily,
Scientists at the University of Sussex have successfully trialed new biodegradable health sensors that could change the way we experience personal healthcare and fitness monitoring technology.
The team at Sussex have developed the new health sensors — such as those worn by runners or patients to monitor heart rate and temperature — using natural elements like rock salt, water and seaweed, combined with graphene. Because they are solely made with ingredients found in nature, the sensors are fully biodegradable, making them more environmentally friendly than commonly used rubber and plastic-based alternatives. Their natural composition also places them within the emerging scientific field of edible electronics — electronic devices that are safe for a person to consume.
Better still, the researchers found that their sustainable seaweed-based sensors actually outperform existing synthetic based hydrogels and nanomaterials, used in wearable health monitors, in terms of sensitivity. Therefore, improving the accuracy, as the more sensitive a sensor, the more accurately it will record a person’s vital signs.
Dr Conor Boland, a materials physics lecturer in the School of Mathematical and Physical Sciences, said: “I was first inspired to use seaweed in the lab after watching MasterChef during lockdown. Seaweed, when used to thicken deserts, gives them a soft and bouncy structure – favored by vegans and vegetarians as an alternative to gelatin. It got me thinking: “what if we could do that with sensing technology?”.
“For me, one of the most exciting aspects to this development is that we have a sensor that is both fully biodegradable and highly effective. The mass production of unsustainable rubber and plastic based health technology could, ironically, pose a risk to human health through microplastics leeching into water sources as they degrade.
“As a new parent, I see it as my responsibility to ensure my research enables the realisation of a cleaner world for all our children.”
Seaweed is first and foremost an insulator, but by adding a critical amount of graphene to a seaweed mixture the scientists were able to create an electrically conductive film. When soaked in a salt bath, the film rapidly absorbs water, resulting in a soft, spongy, electrically conductive hydrogel.
The development has the potential to revolutionise health monitoring technology, as future applications of the clinical grade wearable sensors would look something like a second skin or a temporary tattoo: lightweight, easy to apply, and safe, as they are made with all natural ingredients. This would significantly improve the overall patient experience, without the need for more commonly used and potentially invasive hospital instruments, wires and leads.
Dr Sue Baxter, Director of Innovation and Business Partnerships at the University of Sussex, is excited about the potential benefits of this technology: “At the University of Sussex, we are committed to protecting the future of the planet through sustainability research, expertise and innovation. What’s so exciting about this development from Dr Conor Boland and his team is that it manages to be all at once truly sustainable, affordable, and highly effective – out-performing synthetic alternatives.
“What’s also remarkable for this stage of research – and I think this speaks to the meticulous ground-work that Dr Boland and his team put in when they created their blueprint – is that it’s more than a proof of principle development. Our Sussex scientists have created a device that has real potential for industry development into a product from which you or I could benefit in the relatively near future.”
This latest research breakthrough follows the publication of a blueprint for nanomaterial development from the Sussex scientists in 2019, which presented a method for researchers to follow in order to optimise the development of nanomaterial sensors.
…
Kevin Doty, a Masters student in the School of Mathematical and Physical Sciences, at the University of Sussex, said: “I taught chemistry previously, but decided I wanted to learn more about nanoscience. My gamble paid off, and not only did I enjoy it more than I expected, but I also ended up with an opportunity to utilize the information I had learned to work on a novel idea that has evolved into a first author publication as an MSc student. Learning about nanoscience showed me just how varied and multidisciplinary the field is. Any science background can bring knowledge that can be applied to this field in a unique way. This has led to further studies in a PhD studentship, opening up an all new career path I could not have previously considered.”
It turns out there’s also a hydrogel aspect to this story about a flexible sweat sensor. As for cellulose nanocrystals (CNC), Canada played a leading role in the development of this nanomaterial and I have a bit more about the Canadian CNC scene later in this posting following the link and citation for the research paper. On to the research,
Highly elastic hydrogels constructed by heat-induced hydrogen bond remodeling can switch between wet and dry states (Image by ZHANG Fusheng and LI Qiongya)
A May 8, 2023 news item on phys.org features this work from the Dalian Institute of Chemical Physics of the Chinese Academy Sciences,
Cellulose nanocrystal (CNC), an emerging bio-based material, has been widely applied in fields such as electronics, bioplastics and energy. However, the functional failure of such materials in wet or liquid environments inevitably impairs their development in biomedicine, membrane separation, environmental monitoring, and wearable devices.
Now, a research group led by Prof. Qing Guangyan from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences [CAS] reported a sustainable, insoluble, and chiral photonic cellulose nanocrystal patch for calcium ion (Ca2+) sensing in sweat.
The researchers developed a simple and efficient method to fabricate insoluble CNC-based hydrogels. They found that by utilizing intermolecular hydrogen bond reconstruction, thermal dehydration enabled the optimized CNC composite photonic film to form a stable hydrogel network in an aqueous solution. Moreover, they indicated that the hydrogel could be reversibly switched between dry and wet states, which was convenient for specific functionalization.
The introduction of functionalized molecules by adsorption swelling in a liquid environment resulted in a hydrogel with freeze resistance (–20°C), strong adhesion, good biocompatibility, and high sensitivity to Ca2+.
“This work is expected to facilitate the application of sustainable cellulose sensors to monitor other metabolites (i.e., glucose, urea, and vitamins, etc.),” said Prof. QING. “It also lays foundation for digitally controlled hydrogel systems operating in environment monitoring, membrane separation, and wearable devices.”
FPInnovations is a Canadian research and development (R&D) not-for profit organization that was instrumental in the development of CNC. (If memory serves, they are a spinoff from the University of British Columbia.) There are two Canadian CNC production facilities (that I know of): CelluForce in Québec and Blue Goose Biorefineries in Saskatchewan. I get more information about research into applications for CNC from other parts of the world while the Canadian scene remains mostly silent.
Seems almost magical but it takes years to do this research. That video was posted in September 2019 and the latest research is being announced in a February 28, 2022 news item on phys.org,
Hydrogels have an astonishing ability to swell and take on water. In daily life, they are used in dressings, nappies, and more to lock moisture away. A team of researchers has now found another use: quickly extracting large amounts of freshwater from air using a specially developed hydrogel containing a hygroscopic salt. The study, published in the journal Angewandte Chemie, shows that the salt enhances the moisture uptake of the gel, making it suitable for water harvesting in dry regions.
Hydrogels can absorb and store many times their weight in water. In so doing, the underlying polymer swells considerably by incorporating water. However, to date, use of this property to produce freshwater from atmospheric water has not been feasible, since collecting moisture from the air is still too slow and inefficient.
On the other hand, moisture absorption could be enhanced by adding hygroscopic salts that can rapidly remove large amounts of moisture from the air. However, hygroscopic salts and hydrogels are usually not compatible, as a large amount of salt influences the swelling capability of the hydrogel and thus degrades its properties. In addition, the salt ions are not tightly coordinated within the gel and are easily washed away.
The materials scientist Guihua Yu and his team at the University of Texas at Austin, USA, have now overcome these issues by developing a particularly “salt-friendly” hydrogel. As their study shows, this gel gains the ability to absorb and retain water when combined with a hygroscopic salt. Using their hydrogel, the team were able to extract almost six liters of pure water per kilo of material in 24 hours, from air with 30% relative humidity.
The basis for the new hydrogel was a polymer constructed from zwitterionic molecules. Polyzwitterions carry both positive and negative charged functional groups, which helped the polymer to become more responsive to the salt in this case. Initially, the molecular strands in the polymer were tightly intermingled, but when the researchers added the lithium chloride salt, the strands relaxed and a porous, spongy hydrogel was formed. This hydrogel loaded with the hygroscopic salt was able to incorporate water molecules quickly and easily.
In fact, water incorporation was so quick and easy that the team were able to set up a cyclical system for continuous water separation. They left the hydrogel for an hour each time to absorb atmospheric moisture, then dried the gel in a condenser to collect the condensed water. They repeated this procedure multiple times without it resulting in any substantial loss of the amount of water absorbed, condensed, or collected.
Yu and the team say that the as-prepared hydrogel “should be optimal for efficient moisture harvesting for the potential daily water yield”. They add that polyzwitterionic hydrogels could play a fundamental role in the future for recovering atmospheric water in arid, drought-stricken regions.
Here’s a link to and a citation for the paper,
Polyzwitterionic Hydrogels for Efficient Atmospheric Water Harvesting by Chuxin Lei, Youhong Guo, Weixin Guan, Hengyi Lu, Wen Shi, Guihua Yu. Angewandte Chemie International Edition Volume 61, Issue1 3 March 21, 2022 e202200271 DOI: https://doi.org/10.1002/anie.202200271 First published: 28 January 2022
