Tag Archives: Klas Tybrandt

Connecting nerves to electronics with soft gold

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Gold nanowires that are tissue-like? That’s how this nanogold composite is described in a research paper from researchers at Linköping University (Sweden). Before getting to a link and citation for the paper, here’s an announcement about the work in an August 6, 2024 news item on ScienceDaily,

Gold does not readily lend itself to being turned into long, thin threads. But researchers at Linköping University in Sweden have now managed to create gold nanowires and develop soft electrodes that can be connected to the nervous system. The electrodes are soft as nerves, stretchable and electrically conductive, and are projected to last for a long time in the body.

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An August 6, 2024 Linköping University press release (also on EurekAlert), which originated the news item, provides context for the research,

Some people have a “heart of gold”, so why not “nerves of gold”? In the future, it may be possible to use this precious metal in soft interfaces to connect electronics to the nervous system for medical purposes. Such technology could be used to alleviate conditions such as epilepsy, Parkinson’s disease, paralysis or chronic pain. However, creating an interface where electronics can meet the brain or other parts of the nervous system poses special challenges.

“The classical conductors used in electronics are metals, which are very hard and rigid. The mechanical properties of the nervous system are more reminiscent of soft jelly. In order to get an accurate signal transmission, we need to get very close to the nerve fibres in question, but as the body is constantly in motion, achieving close contact between something that is hard and something that is soft and fragile becomes a problem”, says Klas Tybrandt, professor of materials science at the Laboratory of Organic Electronics at Linköping University, who led the research.

Researchers therefore want to create electrodes that have good conductivity as well as mechanical properties similar to the softness of the body. In recent years, several studies have shown that soft electrodes do not damage the tissue as much as hard electrodes may do. In the current study, published in the journal Small, a group of researchers at Linköping University have developed gold nanowires – a thousand times thinner than a hair – and embedded them in an elastic material to create soft microelectrodes.

“We’ve succeeded in making a new, better nanomaterial from gold nanowires in combination with a very soft silicone rubber. Getting these to work together has resulted in a conductor that has high electrical conductivity, is very soft and made of biocompatible materials that function with the body,” says Klas Tybrandt.

Silicone rubber is used in medical implants, such as breast implants. The soft electrodes also include gold and platinum, metals that are common in medical devices for clinical use. 
However, making long, narrow gold nanostructures is very difficult. This has so far been a major obstacle, but the researchers have now come up with a new way to manufacture gold nanowires. And they do it by using silver nanowires.

As silver has unique properties that make it a very good material to create the kind of nanowires that the researchers are after, it is used in some stretchable nanomaterials. The problem with silver is that it is chemically reactive. In the same way that silver cutlery will discolour over time when chemical reactions occur on the surface, silver in nanowires breaks down so that silver ions leak out. In a high enough concentration, silver ions can be toxic to us.

It was when Laura Seufert, a doctoral student in Klas Tybrandt’s research group, was working on finding a way to synthesize, or “grow”, gold nanowires that she came up with a new approach that opened up new possibilities. At first, it was difficult to control the shape of the nanowires. But then she discovered a way that resulted in very smooth wires. Instead of trying to grow gold nanowires from the beginning, she started with a thin nanowire made of pure silver.

“As it’s possible to make silver nanowires, we take advantage of this and use the silver nanowire as a kind of template on which we grow gold. The next step in the process is to remove the silver. Once that’s done, we have a material that has over 99 per cent gold in it. So it’s a bit of a trick to get around the problem of making long narrow gold nanostructures,” says Klas Tybrandt.

In collaboration with Professor Simon Farnebo at the Department of Biomedical and Clinical Sciences at Linköping University, the researchers behind the study have shown that the soft and elastic microelectrodes can stimulate a rat nerve as well capture signals from the nerve. 

In applications where the soft electronics are to be embedded in the body, the material must last for a long time, preferably for life. The researchers have tested the stability of the new material and concluded that it will last for at least three years, which is better than many of the nanomaterials developed so far.

The research team is now working on refining the material and creating different types of electrodes that are even smaller and can come into closer contact with nerve cells.

The research has been funded with support from, among others, the Swedish Foundation for Strategic Research, the Swedish Research Council, the Knut and Alice Wallenberg Foundation and through the Swedish Government’s strategic research area in advanced functional materials, AFM, at Linköping University.

Here’s a link to and a citation for the paper,

Stretchable Tissue-Like Gold Nanowire Composites with Long-Term Stability for Neural Interfaces by Laura Seufert, Mohammed Elmahmoudy, Charlotte Theunis, Samuel Lienemann, Yuyang Li, Mohsen Mohammadi, Ulrika Boda, Alejandro Carnicer-Lombarte, Renee Kroon, Per O.Å. Persson, Aiman Rahmanudin, Mary J. Donahue, Simon Farnebo, Klas Tybrandt. Small DOI: https://doi.org/10.1002/smll.202402214 First published: 30 June 2024

This paper is open access.

Soft things for your brain

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A March 5, 2018 news item on Nanowerk describes the latest stretchable electrode (Note: A link has been removed),

Klas Tybrandt, principal investigator at the Laboratory of Organic Electronics at Linköping University [Sweden], has developed new technology for long-term stable neural recording. It is based on a novel elastic material composite, which is biocompatible and retains high electrical conductivity even when stretched to double its original length.

The result has been achieved in collaboration with colleagues in Zürich and New York. The breakthrough, which is crucial for many applications in biomedical engineering, is described in an article published in the prestigious scientific journal Advanced Materials (“High-Density Stretchable Electrode Grids for Chronic Neural Recording”).

A March 5, 2018 Linköping University press release, which originated the news item, gives more detail but does not mention that the nanowires are composed of titanium dioxide (you can find additional details in the abstract for the paper; link and citation will be provided later in this posting)),

The coupling between electronic components and nerve cells is crucial not only to collect information about cell signalling, but also to diagnose and treat neurological disorders and diseases, such as epilepsy.

It is very challenging to achieve long-term stable connections that do not damage neurons or tissue, since the two systems, the soft and elastic tissue of the body and the hard and rigid electronic components, have completely different mechanical properties.

Stretchable soft electrodeThe soft electrode stretched to twice its length Photo credit: Thor Balkhed

“As human tissue is elastic and mobile, damage and inflammation arise at the interface with rigid electronic components. It not only causes damage to tissue; it also attenuates neural signals,” says Klas Tybrandt, leader of the Soft Electronics group at the Laboratory of Organic Electronics, Linköping University, Campus Norrköping.

New conductive material

Klas Tybrandt has developed a new conductive material that is as soft as human tissue and can be stretched to twice its length. The material consists of gold coated titanium dioxide nanowires, embedded into silicone rubber. The material is biocompatible – which means it can be in contact with the body without adverse effects – and its conductivity remains stable over time.

“The microfabrication of soft electrically conductive composites involves several challenges. We have developed a process to manufacture small electrodes that also preserves the biocompatibility of the materials. The process uses very little material, and this means that we can work with a relatively expensive material such as gold, without the cost becoming prohibitive,” says Klas Tybrandt.

The electrodes are 50 µm [microns or micrometres] in size and are located at a distance of 200 µm from each other. The fabrication procedure allows 32 electrodes to be placed onto a very small surface. The final probe, shown in the photograph, has a width of 3.2 mm and a thickness of 80 µm.

The soft microelectrodes have been developed at Linköping University and ETH Zürich, and researchers at New York University and Columbia University have subsequently implanted them in the brain of rats. The researchers were able to collect high-quality neural signals from the freely moving rats for 3 months. The experiments have been subject to ethical review, and have followed the strict regulations that govern animal experiments.

Important future applications

Klas Tybrandt, researcher at Laboratory for Organic ElectronicsKlas Tybrandt, researcher at Laboratory for Organic Electronics Photo credit: Thor Balkhed

“When the neurons in the brain transmit signals, a voltage is formed that the electrodes detect and transmit onwards through a tiny amplifier. We can also see which electrodes the signals came from, which means that we can estimate the location in the brain where the signals originated. This type of spatiotemporal information is important for future applications. We hope to be able to see, for example, where the signal that causes an epileptic seizure starts, a prerequisite for treating it. Another area of application is brain-machine interfaces, by which future technology and prostheses can be controlled with the aid of neural signals. There are also many interesting applications involving the peripheral nervous system in the body and the way it regulates various organs,” says Klas Tybrandt.

The breakthrough is the foundation of the research area Soft Electronics, currently being established at Linköping University, with Klas Tybrandt as principal investigator.
liu.se/soft-electronics

A video has been made available (Note: For those who find any notion of animal testing disturbing; don’t watch the video even though it is an animation and does not feature live animals),

Here’s a link to and a citation for the paper,

High-Density Stretchable Electrode Grids for Chronic Neural Recording by Klas Tybrandt, Dion Khodagholy, Bernd Dielacher, Flurin Stauffer, Aline F. Renz, György Buzsáki, and János Vörös. Advanced Materials 2018. DOI: 10.1002/adma.201706520
 First published 28 February 2018

This paper is open access.

Bioelectronics: creating components that speak the body’s own language

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This is work is still in its early stages but the idea that the body could be stimulated to release more of its own pain relievers is exciting. From a Nov. 2, 2016 news item on ScienceDaily,

With a microfabricated ion pump built from organic electronic components, ions can be sent to nerve or muscle cells at the speed of the nervous system and with a precision of a single cell. “Now we can start to develop components that speak the body’s own language,” says Daniel Simon, head of bioelectronics research at the Laboratory of Organic Electronics, Linköping University, Campus Norrköping.

A Nov. 2, 2016 Linköping University press release (also on EurekAlert), which originated the news item, discusses the research in more detail,

Our nerve and muscle cells send signals to each other using ions and molecules. Certain substances, such as the neurotransmitter GABA (gamma aminobutyric acid), are important signal substances throughout the central nervous system. Eighteen months ago, researchers at the Laboratory of Organic Electronics demonstrated an ion pump which researchers at the Karolinska Institutet could use to reduce the sensation of pain in awake, freely-moving rats. The ion pump delivered GABA directly to the rat´s spinal cord. The news that researchers could deliver the body’s own neurotransmitters was published in Science Advances and garnered intense interest all over the world.

The research group at the Laboratory of Organic Electronics has now achieved another major advance and developed a significantly smaller and more rapid ion pump that transmits signals nearly as rapidly as the cells themselves, and with a precision on the scale of an individual cell. …

“Our skilled doctoral students, Amanda Jonsson and Theresia Arbring Sjöström, have succeeded with the last important part of the puzzle in the development of the ion pump. When a signal passes between two synapses it takes 1-10 milliseconds, and we are now very close to the nervous system’s own speed,” says Magnus Berggren, professor of organic electronics and director of the Laboratory of Organic Electronics.

“We conclude that we have produced artificial nerves that can communicate seamlessly with the nervous system. After more than 10 years’ research we have finally got all the parts of the puzzle in place,” he says.

Amanda Jonsson, who together with Theresia Arbring Sjöström is principal author of the article in Science Advances, has developed the pain-alleviating ion pump as part of her doctoral studies. She proudly presents a glass disk with many of the new miniaturized ion pumps. Some pumps have only a single outlet, but others have six tiny point outlets.

“We can make them with several outlets, it’s just as easy as making one. And all of the outlets can be individually controlled. Previously we could only transport ions horizontally and from all outputs at the same time. Now, however, we can deliver the ions vertically, which makes the distance they have to be transported as short as a micrometre,” she explains.

All of the outputs of the ion pump can also be rapidly switched on or off with the aid of micrometre-sized ion diodes.

“The ions are released rapidly by an electrical signal, in the same way that the neurotransmitter is released in a synapse,” says Theresia Arbring Sjöström.

Organic electronic components have a major advantage here: they can conduct both ions and electricity. In this case, the material PEDOT:PSS enables the electrical signals to be converted to chemical signals that the body understands.

The ion diode has recently been developed, as has the material that forms the basis of the new rapid ion pump.

“The new material makes it possible to build with a precision and reliability not possible in previous versions of the ion pump,” says Daniel Simon.

The new ion pump has so far only been tested in the laboratory. The next step will be to test it with live cells and the researchers hope eventually to, for example alleviate pain, stop epileptic seizures, and reduce the symptoms of Parkinsons disease, using exactly the required dose at exactly the affected cells. Communication using the cell´s own language, and the cell´s own speed.

Here’s a link to and a citation for the paper,

Chemical delivery array with millisecond neurotransmitter release by Amanda Jonsson, Theresia Arbring Sjöström, Klas Tybrandt, Magnus Berggren, and Daniel T. Simon. Science Advances  02 Nov 2016: Vol. 2, no. 11, e1601340 DOI: 10.1126/sciadv.1601340

This paper is open access.