̽��ֱ�� of Cambridge - polymer

Soft, stretchy ‘jelly batteries’ inspired by electric eels

sc604 — Wed, 17 Jul 2024 18:00:00 +0000

̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge, took their inspiration from electric eels, which stun their prey with modified muscle cells called electrocytes.

Like electrocytes, the jelly-like materials developed by the Cambridge researchers have a layered structure, like sticky Lego, that makes them capable of delivering an electric current.

̽��ֱ��self-healing jelly batteries can stretch to over ten times their original length without affecting their conductivity – the first time that such stretchability and conductivity has been combined in a single material. ̽��ֱ��results are reported in the journal Science Advances.

̽��ֱ��jelly batteries are made from hydrogels: 3D networks of polymers that contain over 60% water. ̽��ֱ��polymers are held together by reversible on/off interactions that control the jelly’s mechanical properties.

̽��ֱ��ability to precisely control mechanical properties and mimic the characteristics of human tissue makes hydrogels ideal candidates for soft robotics and bioelectronics; however, they need to be both conductive and stretchy for such applications.

“It’s difficult to design a material that is both highly stretchable and highly conductive, since those two properties are normally at odds with one another,” said first author Stephen O’Neill, from Cambridge’s Yusuf Hamied Department of Chemistry. “Typically, conductivity decreases when a material is stretched.”

“Normally, hydrogels are made of polymers that have a neutral charge, but if we charge them, they can become conductive,” said co-author Dr Jade McCune, also from the Department of Chemistry. “And by changing the salt component of each gel, we can make them sticky and squish them together in multiple layers, so we can build up a larger energy potential.”

Conventional electronics use rigid metallic materials with electrons as charge carriers, while the jelly batteries use ions to carry charge, like electric eels.

̽��ֱ��hydrogels stick strongly to each other because of reversible bonds that can form between the different layers, using barrel-shaped molecules called cucurbiturils that are like molecular handcuffs. ̽��ֱ��strong adhesion between layers provided by the molecular handcuffs allows for the jelly batteries to be stretched, without the layers coming apart and crucially, without any loss of conductivity.

̽��ֱ��properties of the jelly batteries make them promising for future use in biomedical implants, since they are soft and mould to human tissue. “We can customise the mechanical properties of the hydrogels so they match human tissue,” said Professor Oren Scherman, Director of the Melville Laboratory for Polymer Synthesis, who led the research in collaboration with Professor George Malliaras from the Department of Engineering. “Since they contain no rigid components such as metal, a hydrogel implant would be much less likely to be rejected by the body or cause the build-up of scar tissue.”

In addition to their softness, the hydrogels are also surprisingly tough. They can withstand being squashed without permanently losing their original shape, and can self-heal when damaged.

̽��ֱ��researchers are planning future experiments to test the hydrogels in living organisms to assess their suitability for a range of medical applications.

̽��ֱ��research was funded by the European Research Council and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI). Oren Scherman is a Fellow of Jesus College, Cambridge.

Reference:
Stephen J.K. O’Neill et al. ‘Highly Stretchable Dynamic Hydrogels for Soft Multilayer Electronics.’ Science Advances (2024). DOI: 10.1126/sciadv.adn5142

Researchers have developed soft, stretchable ‘jelly batteries’ that could be used for wearable devices or soft robotics, or even implanted in the brain to deliver drugs or treat conditions such as epilepsy.

Scherman Lab

Jelly batteries

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

‘Super jelly’ can survive being run over by a car

sc604 — Thu, 25 Nov 2021 16:02:38 +0000

̽��ֱ��soft-yet-strong material, developed by a team at the ̽��ֱ�� of Cambridge, looks and feels like a squishy jelly, but acts like an ultra-hard, shatterproof glass when compressed, despite its high water content.

̽��ֱ��non-water portion of the material is a network of polymers held together by reversible on/off interactions that control the material’s mechanical properties. This is the first time that such significant resistance to compression has been incorporated into a soft material.

̽��ֱ��‘super jelly’ could be used for a wide range of potential applications, including soft robotics, bioelectronics or even as a cartilage replacement for biomedical use. ̽��ֱ��results are reported in the journal Nature Materials.

̽��ֱ��way materials behave – whether they’re soft or firm, brittle or strong – is dependent upon their molecular structure. Stretchy, rubber-like hydrogels have lots of interesting properties that make them a popular subject of research – such as their toughness and self-healing capabilities – but making hydrogels that can withstand being compressed without getting crushed is a challenge.

“In order to make materials with the mechanical properties we want, we use crosslinkers, where two molecules are joined through a chemical bond,” said Dr Zehuan Huang from the Yusuf Hamied Department of Chemistry, the study’s first author. “We use reversible crosslinkers to make soft and stretchy hydrogels, but making a hard and compressible hydrogel is difficult and designing a material with these properties is completely counterintuitive.”

Working in the lab of Professor Oren A Scherman, who led the research, the team used barrel-shaped molecules called cucurbiturils to make a hydrogel that can withstand compression. ̽��ֱ��cucurbituril is the crosslinking molecule that holds two guest molecules in its cavity – like a molecular handcuff. ̽��ֱ��researchers designed guest molecules that prefer to stay inside the cavity for longer than normal, which keeps the polymer network tightly linked, allowing for it to withstand compression.

“At 80% water content, you’d think it would burst apart like a water balloon, but it doesn’t: it stays intact and withstands huge compressive forces,” said Scherman, Director of the ̽��ֱ��’s Melville Laboratory for Polymer Synthesis. “ ̽��ֱ��properties of the hydrogel are seemingly at odds with each other.”

“ ̽��ֱ��way the hydrogel can withstand compression was surprising, it wasn’t like anything we’ve seen in hydrogels,” said co-author Dr Jade McCune, also from the Department of Chemistry. “We also found that the compressive strength could be easily controlled through simply changing the chemical structure of the guest molecule inside the handcuff.”

To make their glass-like hydrogels, the team chose specific guest molecules for the handcuff. Altering the molecular structure of guest molecules within the handcuff allowed the dynamics of the material to ‘slow down’ considerably, with the mechanical performance of the final hydrogel ranging from rubber-like to glass-like states.

“People have spent years making rubber-like hydrogels, but that’s just half of the picture,” said Scherman. “We’ve revisited traditional polymer physics and created a new class of materials that span the whole range of material properties from rubber-like to glass-like, completing the full picture.”

̽��ֱ��researchers used the material to make a hydrogel pressure sensor for real-time monitoring of human motions, including standing, walking and jumping.

“To the best of our knowledge, this is the first time that glass-like hydrogels have been made. We’re not just writing something new into the textbooks, which is really exciting, but we’re opening a new chapter in the area of high-performance soft materials,” said Huang.

Researchers from the Scherman lab are currently working to further develop these glass-like materials towards biomedical and bioelectronic applications in collaboration with experts from engineering and materials science. ̽��ֱ��research was funded in part by the Leverhulme Trust and a Marie Skłodowska-Curie Fellowship. Oren Scherman is a Fellow of Jesus College.

Reference:
Zehuan Huang et al. ‘Highly compressible glass-like supramolecular polymer networks.’ Nature Materials (2021). DOI: 10.1038/s41563-021-01124-x

Researchers have developed a jelly-like material that can withstand the equivalent of an elephant standing on it, and completely recover to its original shape, even though it’s 80% water.

At 80% water content, you’d think it would burst apart like a water balloon, but it doesn’t: it stays intact and withstands huge compressive forces

Oren Scherman

‘Super jelly’ can survive being run over by a car

Zehuan Huang

Super jelly

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Low-cost plastic sensors could monitor a range of health conditions

sc604 — Fri, 22 Jun 2018 18:00:00 +0000

̽��ֱ��sensor can measure the amount of critical metabolites, such as lactate or glucose, that are present in sweat, tears, saliva or blood, and, when incorporated into a diagnostic device, could allow health conditions to be monitored quickly, cheaply and accurately. ̽��ֱ��new device has a far simpler design than existing sensors, and opens up a wide range of new possibilities for health monitoring down to the cellular level. ̽��ֱ��results are reported in the journal Science Advances.

̽��ֱ��device was developed by a team led by the ̽��ֱ�� of Cambridge and King Abdullah ̽��ֱ�� of Science and Technology (KAUST) in Saudi Arabia. Semiconducting plastics such as those used in the current work are being developed for use in solar cells and flexible electronics, but have not yet seen widespread use in biological applications.

“In our work, we’ve overcome many of the limitations of conventional electrochemical biosensors that incorporate enzymes as the sensing material,” said lead author Dr Anna-Maria Pappa, a postdoctoral researcher in Cambridge’s Department of Chemical Engineering and Biotechnology. “In conventional biosensors, the communication between the sensor’s electrode and the sensing material is not very efficient, so it’s been necessary to add molecular wires to facilitate and ‘boost’ the signal.”

To build their sensor, Pappa and her colleagues used a newly-synthesised polymer developed at Imperial College that acts as a molecular wire, directly accepting the electrons produced during electrochemical reactions. When the material comes into contact with a liquid such as sweat, tears or blood, it absorbs ions and swells, becoming merged with the liquid. This leads to significantly higher sensitivity compared to traditional sensors made of metal electrodes.

Additionally, when the sensors are incorporated into more complex circuits, such as transistors, the signal can be amplified and respond to tiny fluctuations in metabolite concentration, despite the tiny size of the devices.

Initial tests of the sensors were used to measure levels of lactate, which is useful in fitness applications or to monitor patients following surgery. However, according to the researchers, the sensor can be easily modified to detect other metabolites, such as glucose or cholesterol by incorporating the appropriate enzyme, and the concentration range that the sensor can detect can be adjusted by changing the device’s geometry.

“This is the first time that it’s been possible to use an electron accepting polymer that can be tailored to improve communication with the enzymes, which allows for the direct detection of a metabolite: this hasn’t been straightforward until now,” said Pappa. “It opens up new directions in biosensing, where materials can be designed to interact with a specific metabolite, resulting in far more sensitive and selective sensors.”

Since the sensor does not consist of metals such as gold or platinum, it can be manufactured at a lower cost and can be easily incorporated in flexible and stretchable substrates, enabling their implementation in wearable or implantable sensing applications.

“An implantable device could allow us to monitor the metabolic activity of the brain in real time under stress conditions, such as during or immediately before a seizure and could be used to predict seizures or to assess treatment,” said Pappa.

̽��ֱ��researchers now plan to develop the sensor to monitor metabolic activity of human cells in real time outside the body. ̽��ֱ��Bioelectronic Systems and Technologies group where Pappa is based is focused on developing models that can closely mimic our organs, along with technologies that can accurately assess them in real-time. ̽��ֱ��developed sensor technology can be used with these models to test the potency or toxicity of drugs.

̽��ֱ��research was funded by the Marie Curie Foundation, the KAUST Office of Sponsored Research, and the Engineering and Physical Sciences Research Council.

Reference:
A.M. Pappa et al. ‘Direct metabolite detection with an n-type accumulation mode organic electrochemical transistor.’ Science Advances (2018). DOI: 10.1126/sciadv.aat0911

An international team of researchers have developed a low-cost sensor made from semiconducting plastic that can be used to diagnose or monitor a wide range of health conditions, such as surgical complications or neurodegenerative diseases.

This work opens up new directions in biosensing, where materials can be designed to interact with a specific metabolite, resulting in far more sensitive and selective sensors.

Anna-Maria Pappa

KAUST

Polymer biosensor

Researcher profile: Anna Maria Pappa

I strongly believe that through diversity comes creativity, comes progress. I qualified as an engineer, and later earned my Master’s degree at Aristotle ̽��ֱ�� of Thessaloniki in Greece. My PhD is in Bioelectronics from École des Mines de Saint-Étienne in France and leaving my comfort zone to study abroad proved to be an invaluable experience. I met people from different cultures and mindsets from all over the world, stretched my mind and expanded my horizons.

Now, I always look for those with different views. I travel frequently for conferences and visit other laboratories across Europe, the United States and Saudi Arabia. When you work in a multidisciplinary field it is essential to establish and keep good collaborations: this is the only way to achieve the desired outcome.

Being part of a ̽��ֱ�� where some of the world's most brilliant scientists studied and worked is a great privilege. Cambridge combines a historic and traditional atmosphere with cutting-edge research in an open, multicultural society. ̽��ֱ��state-of-the-art facilities, the openness in innovation and strong collaborations provide a unique combination that can only lead to excellence.

As an engineer, creating solutions to important yet unresolved issues for healthcare is what truly motivates me. I’m working on a drug discovery platform using bioelectronics, and my work sets out to improve and accelerate drug discovery by providing novel technological solutions for drug screening and disease management. I hope my research will lead to a product that will impact healthcare. In the future, I imagine a healthcare system where the standard one-size-fits-all approach shifts to a more personalised and tailored model.

I’m a strong advocate for Women in STEMM, and in October 2017 I was awarded a L'Oréal-UNESCO For Women in Science Fellowship, an award that honours the contributions of women in science. For me, the award not only represents a scientific distinction but also gives me the unique opportunity, as an ambassador of science, to inspire and motivate young girls to follow the career they desire.

I think it’s absolutely vital, at every opportunity, for all of us to honour and promote girls and women in science. Unfortunately, women still struggle when it comes to joining male-dominated fields, and even to establish themselves later at senior roles. We still face stereotypes and social restrictions, even if it is not as obvious today as it was in the past. A question I always ask girls during my outreach activities at schools, is, ‘do I look like a scientist?’, and the answer I most often get is no! I think this misperception of what STEMM professionals look like, or of what they actually do on a daily basis is what discourages girls early on to follow STEMM careers. This needs to change.

Yes