̽��ֱ�� of Cambridge - Jade McCune

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

Nano ‘camera’ made using molecular glue allows real-time monitoring of chemical reactions

sc604 — Thu, 02 Sep 2021 14:59:34 +0000

̽��ֱ��device, made by a team from the ̽��ֱ�� of Cambridge, combines tiny semiconductor nanocrystals called quantum dots and gold nanoparticles using molecular glue called cucurbituril (CB). When added to water with the molecule to be studied, the components self-assemble in seconds into a stable, powerful tool that allows the real-time monitoring of chemical reactions.

̽��ֱ��camera harvests light within the semiconductors, inducing electron transfer processes like those that occur in photosynthesis, which can be monitored using incorporated gold nanoparticle sensors and spectroscopic techniques. They were able to use the camera to observe chemical species which had been previously theorised but not directly observed.

̽��ֱ��platform could be used to study a wide range of molecules for a variety of potential applications, such as the improvement of photocatalysis and photovoltaics for renewable energy. ̽��ֱ��results are reported in the journal Nature Nanotechnology.

Nature controls the assemblies of complex structures at the molecular scale through self-limiting processes. However, mimicking these processes in the lab is usually time-consuming, expensive and reliant on complex procedures.

“In order to develop new materials with superior properties, we often combine different chemical species together to come up with a hybrid material that has the properties we want,” said Professor Oren Scherman from Cambridge’s Yusuf Hamied Department of Chemistry, who led the research. “But making these hybrid nanostructures is difficult, and you often end up with uncontrolled growth or materials that are unstable.”

̽��ֱ��new method that Scherman and his colleagues from Cambridge’s Cavendish Laboratory and ̽��ֱ�� College London developed uses cucurbituril – a molecular glue which interacts strongly with both semiconductor quantum dots and gold nanoparticles. ̽��ֱ��researchers used small semiconductor nanocrystals to control the assembly of larger nanoparticles through a process they coined interfacial self-limiting aggregation. ̽��ֱ��process leads to permeable and stable hybrid materials that interact with light. ̽��ֱ��camera was used to observe photocatalysis and track light-induced electron transfer.

“We were surprised how powerful this new tool is, considering how straightforward it is to assemble,” said first author Dr Kamil Sokołowski, also from the Department of Chemistry.

To make their nano camera, the team added the individual components, along with the molecule they wanted to observe, to water at room temperature. Previously, when gold nanoparticles were mixed with the molecular glue in the absence of quantum dots, the components underwent unlimited aggregation and fell out of solution. However, with the strategy developed by the researchers, quantum dots mediate the assembly of these nanostructures so that the semiconductor-metal hybrids control and limit their own size and shape. In addition, these structures stay stable for weeks.

“This self-limiting property was surprising, it wasn’t anything we expected to see,” said co-author Dr Jade McCune, also from the Department of Chemistry. “We found that the aggregation of one nanoparticulate component could be controlled through the addition of another nanoparticle component.”

When the researchers mixed the components together, the team used spectroscopy to observe chemical reactions in real time. Using the camera, they were able to observe the formation of radical species – a molecule with an unpaired electron – and products of their assembly such as sigma dimeric viologen species, where two radicals form a reversible carbon-carbon bond. ̽��ֱ��latter species had been theorised but never observed.

“People have spent their whole careers getting pieces of matter to come together in a controlled way,” said Scherman, who is also Director of the Melville Laboratory. “This platform will unlock a wide range of processes, including many materials and chemistries that are important for sustainable technologies. ̽��ֱ��full potential of semiconductor and plasmonic nanocrystals can now be explored, providing an opportunity to simultaneously induce and observe photochemical reactions.”

“This platform is a really big toolbox considering the number of metal and semiconductor building blocks that can be now coupled together using this chemistry– it opens up lots of new possibilities for imaging chemical reactions and sensing through taking snapshots of monitored chemical systems,” said Sokołowski. “ ̽��ֱ��simplicity of the setup means that researchers no longer need complex, expensive methods to get the same results.”

Researchers from the Scherman lab are currently working to further develop these hybrids towards artificial photosynthetic systems and (photo)catalysis where electron-transfer processes can be observed directly in real time. ̽��ֱ��team is also looking at mechanisms of carbon-carbon bond formation as well as electrode interfaces for battery applications.

̽��ֱ��research was carried out in collaboration with Professor Jeremy Baumberg at Cambridge’s Cavendish Laboratory and Dr Edina Rosta at ̽��ֱ�� College London. It was funded in part by the Engineering and Physical Sciences Research Council (EPSRC).

Reference:
Kamil Sokołowski et al. ‘Nanoparticle surfactants for kinetically arrested photoactive assemblies to track light-induced electron transfer.’ Nature Nanotechnology (2021). DOI: 10.1038/s41565-021-00949-6

Researchers have made a tiny camera, held together with ‘molecular glue’ that allows them to observe chemical reactions in real time.

This platform is a really big toolbox – it opens up lots of new possibilities for imaging chemical reactions

Kamil Sokołowski

Scherman Group

Nano camera

Yes