Tag Archives: electrodes

Graphene-based neural probes

I have two news bits (dated almost one month apart) about the use of graphene in neural probes, one from the European Union and the other from Korea.

European Union (EU)

This work is being announced by the European Commission’s (a subset of the EU) Graphene Flagship (one of two mega-funding projects announced in 2013; 1B Euros each over ten years for the Graphene Flagship and the Human Brain Project).

According to a March 27, 2017 news item on ScienceDaily, researchers have developed a graphene-based neural probe that has been tested on rats,

Measuring brain activity with precision is essential to developing further understanding of diseases such as epilepsy and disorders that affect brain function and motor control. Neural probes with high spatial resolution are needed for both recording and stimulating specific functional areas of the brain. Now, researchers from the Graphene Flagship have developed a new device for recording brain activity in high resolution while maintaining excellent signal to noise ratio (SNR). Based on graphene field-effect transistors, the flexible devices open up new possibilities for the development of functional implants and interfaces.

The research, published in 2D Materials, was a collaborative effort involving Flagship partners Technical University of Munich (TU Munich; Germany), Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS; Spain), Spanish National Research Council (CSIC; Spain), The Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN; Spain) and the Catalan Institute of Nanoscience and Nanotechnology (ICN2; Spain).

Caption: Graphene transistors integrated in a flexible neural probe enables electrical signals from neurons to be measured with high accuracy and density. Inset: The tip of the probe contains 16 flexible graphene transistors. Credit: ICN2

A March 27, 2017 Graphene Flagship press release on EurekAlert, which originated the news item, describes the work,  in more detail,

The devices were used to record the large signals generated by pre-epileptic activity in rats, as well as the smaller levels of brain activity during sleep and in response to visual light stimulation. These types of activities lead to much smaller electrical signals, and are at the level of typical brain activity. Neural activity is detected through the highly localised electric fields generated when neurons fire, so densely packed, ultra-small measuring devices is important for accurate brain readings.

The neural probes are placed directly on the surface of the brain, so safety is of paramount importance for the development of graphene-based neural implant devices. Importantly, the researchers determined that the graphene-based probes are non-toxic, and did not induce any significant inflammation.

Devices implanted in the brain as neural prosthesis for therapeutic brain stimulation technologies and interfaces for sensory and motor devices, such as artificial limbs, are an important goal for improving quality of life for patients. This work represents a first step towards the use of graphene in research as well as clinical neural devices, showing that graphene-based technologies can deliver the high resolution and high SNR needed for these applications.

First author Benno Blaschke (TU Munich) said “Graphene is one of the few materials that allows recording in a transistor configuration and simultaneously complies with all other requirements for neural probes such as flexibility, biocompability and chemical stability. Although graphene is ideally suited for flexible electronics, it was a great challenge to transfer our fabrication process from rigid substrates to flexible ones. The next step is to optimize the wafer-scale fabrication process and improve device flexibility and stability.”

Jose Antonio Garrido (ICN2), led the research. He said “Mechanical compliance is an important requirement for safe neural probes and interfaces. Currently, the focus is on ultra-soft materials that can adapt conformally to the brain surface. Graphene neural interfaces have shown already great potential, but we have to improve on the yield and homogeneity of the device production in order to advance towards a real technology. Once we have demonstrated the proof of concept in animal studies, the next goal will be to work towards the first human clinical trial with graphene devices during intraoperative mapping of the brain. This means addressing all regulatory issues associated to medical devices such as safety, biocompatibility, etc.”

Caption: The graphene-based neural probes were used to detect rats’ responses to visual stimulation, as well as neural signals during sleep. Both types of signals are small, and typically difficult to measure. Credit: ICN2

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

Mapping brain activity with flexible graphene micro-transistors by Benno M Blaschke, Núria Tort-Colet, Anton Guimerà-Brunet, Julia Weinert, Lionel Rousseau, Axel Heimann, Simon Drieschner, Oliver Kempski, Rosa Villa, Maria V Sanchez-Vives. 2D Materials, Volume 4, Number 2 DOI https://doi.org/10.1088/2053-1583/aa5eff Published 24 February 2017

© 2017 IOP Publishing Ltd

This paper is behind a paywall.

Korea

While this research from Korea was published more recently, the probe itself has not been subjected to in vivo (animal testing). From an April 19, 2017 news item on ScienceDaily,

Electrodes placed in the brain record neural activity, and can help treat neural diseases like Parkinson’s and epilepsy. Interest is also growing in developing better brain-machine interfaces, in which electrodes can help control prosthetic limbs. Progress in these fields is hindered by limitations in electrodes, which are relatively stiff and can damage soft brain tissue.

Designing smaller, gentler electrodes that still pick up brain signals is a challenge because brain signals are so weak. Typically, the smaller the electrode, the harder it is to detect a signal. However, a team from the Daegu Gyeongbuk Institute of Science & Technology [DGIST} in Korea developed new probes that are small, flexible and read brain signals clearly.

This is a pretty interesting way to illustrate the research,

Caption: Graphene and gold make a better brain probe. Credit: DGIST

An April 19, 2017 DGIST press release (also on EurekAlert), which originated the news item, expands on the theme (Note: A link has been removed),

The probe consists of an electrode, which records the brain signal. The signal travels down an interconnection line to a connector, which transfers the signal to machines measuring and analysing the signals.

The electrode starts with a thin gold base. Attached to the base are tiny zinc oxide nanowires, which are coated in a thin layer of gold, and then a layer of conducting polymer called PEDOT. These combined materials increase the probe’s effective surface area, conducting properties, and strength of the electrode, while still maintaining flexibility and compatibility with soft tissue.

Packing several long, thin nanowires together onto one probe enables the scientists to make a smaller electrode that retains the same effective surface area of a larger, flat electrode. This means the electrode can shrink, but not reduce signal detection. The interconnection line is made of a mix of graphene and gold. Graphene is flexible and gold is an excellent conductor. The researchers tested the probe and found it read rat brain signals very clearly, much better than a standard flat, gold electrode.

“Our graphene and nanowires-based flexible electrode array can be useful for monitoring and recording the functions of the nervous system, or to deliver electrical signals to the brain,” the researchers conclude in their paper recently published in the journal ACS Applied Materials and Interfaces.

The probe requires further clinical tests before widespread commercialization. The researchers are also interested in developing a wireless version to make it more convenient for a variety of applications.

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

Enhancement of Interface Characteristics of Neural Probe Based on Graphene, ZnO Nanowires, and Conducting Polymer PEDOT by Mingyu Ryu, Jae Hoon Yang, Yumi Ahn, Minkyung Sim, Kyung Hwa Lee, Kyungsoo Kim, Taeju Lee, Seung-Jun Yoo, So Yeun Kim, Cheil Moon, Minkyu Je, Ji-Woong Choi, Youngu Lee, and Jae Eun Jang. ACS Appl. Mater. Interfaces, 2017, 9 (12), pp 10577–10586 DOI: 10.1021/acsami.7b02975 Publication Date (Web): March 7, 2017

Copyright © 2017 American Chemical Society

This paper is behind a paywall.

Going underground to observe atoms in a bid for better batteries

A Jan. 16, 2017 news item on ScienceDaily describes what lengths researchers at Stanford University (US) will go to in pursuit of their goals,

In a lab 18 feet below the Engineering Quad of Stanford University, researchers in the Dionne lab camped out with one of the most advanced microscopes in the world to capture an unimaginably small reaction.

The lab members conducted arduous experiments — sometimes requiring a continuous 30 hours of work — to capture real-time, dynamic visualizations of atoms that could someday help our phone batteries last longer and our electric vehicles go farther on a single charge.

Toiling underground in the tunneled labs, they recorded atoms moving in and out of nanoparticles less than 100 nanometers in size, with a resolution approaching 1 nanometer.

A Jan. 16, 2017 Stanford University news release (also on EurekAlert) by Taylor Kubota, which originated the news item, provides more detail,

“The ability to directly visualize reactions in real time with such high resolution will allow us to explore many unanswered questions in the chemical and physical sciences,” said Jen Dionne, associate professor of materials science and engineering at Stanford and senior author of the paper detailing this work, published Jan. 16 [2017] in Nature Communications. “While the experiments are not easy, they would not be possible without the remarkable advances in electron microscopy from the past decade.”

Their experiments focused on hydrogen moving into palladium, a class of reactions known as an intercalation-driven phase transition. This reaction is physically analogous to how ions flow through a battery or fuel cell during charging and discharging. Observing this process in real time provides insight into why nanoparticles make better electrodes than bulk materials and fits into Dionne’s larger interest in energy storage devices that can charge faster, hold more energy and stave off permanent failure.

Technical complexity and ghosts

For these experiments, the Dionne lab created palladium nanocubes, a form of nanoparticle, that ranged in size from about 15 to 80 nanometers, and then placed them in a hydrogen gas environment within an electron microscope. The researchers knew that hydrogen would change both the dimensions of the lattice and the electronic properties of the nanoparticle. They thought that, with the appropriate microscope lens and aperture configuration, techniques called scanning transmission electron microscopy and electron energy loss spectroscopy might show hydrogen uptake in real time.

After months of trial and error, the results were extremely detailed, real-time videos of the changes in the particle as hydrogen was introduced. The entire process was so complicated and novel that the first time it worked, the lab didn’t even have the video software running, leading them to capture their first movie success on a smartphone.

Following these videos, they examined the nanocubes during intermediate stages of hydrogenation using a second technique in the microscope, called dark-field imaging, which relies on scattered electrons. In order to pause the hydrogenation process, the researchers plunged the nanocubes into an ice bath of liquid nitrogen mid-reaction, dropping their temperature to 100 degrees Kelvin (-280 F). These dark-field images served as a way to check that the application of the electron beam hadn’t influenced the previous observations and allowed the researchers to see detailed structural changes during the reaction.

“With the average experiment spanning about 24 hours at this low temperature, we faced many instrument problems and called Ai Leen Koh [co-author and research scientist at Stanford’s Nano Shared Facilities] at the weirdest hours of the night,” recalled Fariah Hayee, co-lead author of the study and graduate student in the Dionne lab. “We even encountered a ‘ghost-of-the-joystick problem,’ where the joystick seemed to move the sample uncontrollably for some time.”

While most electron microscopes operate with the specimen held in a vacuum, the microscope used for this research has the advanced ability to allow the researchers to introduce liquids or gases to their specimen.

“We benefit tremendously from having access to one of the best microscope facilities in the world,” said Tarun Narayan, co-lead author of this study and recent doctoral graduate from the Dionne lab. “Without these specific tools, we wouldn’t be able to introduce hydrogen gas or cool down our samples enough to see these processes take place.”

Pushing out imperfections

Aside from being a widely applicable proof of concept for this suite of visualization techniques, watching the atoms move provides greater validation for the high hopes many scientists have for nanoparticle energy storage technologies.

The researchers saw the atoms move in through the corners of the nanocube and observed the formation of various imperfections within the particle as hydrogen moved within it. This sounds like an argument against the promise of nanoparticles but that’s because it’s not the whole story.

“The nanoparticle has the ability to self-heal,” said Dionne. “When you first introduce hydrogen, the particle deforms and loses its perfect crystallinity. But once the particle has absorbed as much hydrogen as it can, it transforms itself back to a perfect crystal again.”

The researchers describe this as imperfections being “pushed out” of the nanoparticle. This ability of the nanocube to self-heal makes it more durable, a key property needed for energy storage materials that can sustain many charge and discharge cycles.

Looking toward the future

As the efficiency of renewable energy generation increases, the need for higher quality energy storage is more pressing than ever. It’s likely that the future of storage will rely on new chemistries and the findings of this research, including the microscopy techniques the researchers refined along the way, will apply to nearly any solution in those categories.

For its part, the Dionne lab has many directions it can go from here. The team could look at a variety of material compositions, or compare how the sizes and shapes of nanoparticles affect the way they work, and, soon, take advantage of new upgrades to their microscope to study light-driven reactions. At present, Hayee has moved on to experimenting with nanorods, which have more surface area for the ions to move through, promising potentially even faster kinetics.

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

Direct visualization of hydrogen absorption dynamics in individual palladium nanoparticles by Tarun C. Narayan, Fariah Hayee, Andrea Baldi, Ai Leen Koh, Robert Sinclair, & Jennifer A. Dionne. Nature Communications 8, Article number: 14020 (2017) doi:10.1038/ncomms14020 Published online: 16 January 2017

This paper is open access.

Saving silver; a new kind of electrode

An Aug. 1, 2015 news item on Nanotechnology Now highlights work from Germany’s Helmholtz-Zentrum Berlin für Materialien und Energie (Helmholtz Zentrum Berlin),

The electrodes for connections on the “sunny side” of a solar cell need to be not just electrically conductive, but transparent as well. As a result, electrodes are currently made either by using thin strips of silver in the form of a coarse-meshed grid squeegeed onto a surface, or by applying a transparent layer of electrically conductive indium tin oxide (ITO) compound. Neither of these are ideal solutions, however. This is because silver is a precious metal and relatively expensive, and silver particles with nanoscale dimensions oxidise particularly rapidly; meanwhile, indium is one of the rarest elements on earth crust and probably will only continue to be available for a few more years.

Manuela Göbelt on the team of Prof. Silke Christiansen has now developed an elegant new solution using only a fraction of the silver and entirely devoid of indium to produce a technologically intriguing electrode. The doctoral student initially made a suspension of silver nanowires in ethanol using wet-chemistry techniques. She then transferred this suspension with a pipette onto a substrate, in this case a silicon solar cell. As the solvent is evaporated, the silver nanowires organise themselves into a loose mesh that remains transparent, yet dense enough to form uninterrupted current paths.

A July 31, 2015 Helmholtz Zentrum Berlin press release (also on EurekAlert), which originated the news item, describes the work in more detail,

Subsequently, Göbelt used an atomic layer deposition technique to gradually apply a coating of a highly doped wide bandgap semiconductor known as AZO. AZO consists of zinc oxide that is doped with aluminium. It is much less expensive than ITO and just as transparent, but not quite as electrically conductive. This process caused tiny AZO crystals to form on the silver nanowires, enveloped them completely, and finally filled in the interstices. The silver nanowires, measuring about 120 nanometres in diameter, were covered with a layer of about 100 nanometres of AZO and encapsulated by this process.

Quality map calculated

Measurements of the electrical conductivity showed that the newly developed composite electrode is comparable to a conventional silver grid electrode. However, its performance depends on how well the nanowires are interconnected, which is a function of the wire lengths and the concentration of silver nanowires in the suspension. The scientists were able to specify the degree of networking in advance with computers. Using specially developed image analysis algorithms, they could evaluate images taken with a scanning electron microscope and predict the electrical conductivity of the electrodes from them.

“We are investigating where a given continuous conductive path of nanowires is interrupted to see where the network is not yet optimum”, explains Ralf Keding. Even with high-performance computers, it still initially took nearly five days to calculate a good “quality map” of the electrode. The software is now being optimised to reduce the computation time. “The image analysis has given us valuable clues about where we need to concentrate our efforts to increase the performance of the electrode, such as increased networking to improve areas of poor coverage by changing the wire lengths or the wire concentration in solution”, says Göbelt.

Practical aternative to conventional electrodes

“We have developed a practical, cost-effective alternative to conventional screen-printed grid electrodes and to the common ITO type that is threatened however by material bottlenecks”, says Christiansen, who heads the Institute of Nanoarchitectures for Energy Conversion at HZB and additionally directs a project team at the Max Planck Institute for the Science of Light (MPL).

Only a fraction of silver, nearly no shadow effects

The new electrodes can actually be made using only 0.3 grams of silver per square metre, while conventional silver grid electrodes require closer to between 15 and 20 grams of silver. In addition, the new electrode casts a considerably smaller shadow on the solar cell. “The network of silver nanowires is so fine that almost no light for solar energy conversion is lost in the cell due to the shadow”, explains Göbelt. On the contrary, she hopes “it might even be possible for the silver nanowires to scatter light into the solar cell absorbers in a controlled fashion through what are known as plasmonic effects.”

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

Encapsulation of silver nanowire networks by atomic layer deposition for indium-free transparent electrodes by Manuela Göbelt, Ralf Keding, Sebastian W. Schmitt, Björn Hoffmann, Sara Jäckle, Michael Latzel, Vuk V. Radmilović, Velimir R. Radmilović,  Erdmann Spiecker, and Silke Christiansen. Nano Energy Volume 16, September 2015, Pages 196–206 doi:10.1016/j.nanoen.2015.06.027

This paper is behind a paywall.

Just how bendy are the new organic semiconductors?

In all the excitement about flexible electronics, an interesting question about performance, which seems to have been overlooked until now (how bendy are they?), is being answered by scientists, according to a May 5, 2015 University of Massachusetts at Amherst news release (also on EurekAlert),

A revolution is coming in flexible electronic technologies as cheaper, more flexible, organic transistors come on the scene to replace expensive, rigid, silicone-based semiconductors, but not enough is known about how bending in these new thin-film electronic devices will affect their performance, say materials scientists at the University of Massachusetts Amherst.

They are the first to apply inhomogeneous deformations, that is strain, to the conducting channel of an organic transistor and to understand the observed effects, says Reyes-Martinez [Marcos Reyes-Martinez], who conducted the series of experiments as part of his doctoral work.

As he explains, “This is relevant to today’s tech industry because transistors drive the logic of all the consumer electronics we use. In the screen on your smart phone, for example, every little pixel that makes up the image is turned on and off by hundreds of thousands or even millions of miniaturized transistors.”

“Traditionally, the transistors are rigid, made of an inorganic material such as silicon,” he adds. “We’re working with a crystalline semiconductorcalled rubrene, which is an organic, carbon-based material that has performance factors, such as charge-carrier mobility, surpassing those measured in amorphous silicon. Organic semiconductors are an interesting alternative to silicon because their properties can be tuned to make them easily processed, allowing them to coat a variety of surfaces, including soft substrates at relatively low temperatures. As a result, devices based on organic semiconductors are projected to be cheaper since they do not require high temperatures, clean rooms and expensive processing steps like silicon does.”

Until now, Reyes-Martinez notes, most researchers have focused on controlling the detrimental effects of mechanical deformation to atransistor’s electrical properties. But in their series of systematic experiments, the UMass Amherst team discovered that mechanical deformations only decrease performance under certain conditions, and actually can enhance or have no effect in other instances.

“Our goal was not only to show these effects, but to explain and understand them. What we’ve done istake advantage of the ordered structure of ultra-thin organic single crystals of rubrene to fabricate high-perfomance, thin-film transistors,” he says. “This is the first time that anyone has carried out detailed fundamental work at these length scales with a single crystal.”

Though single crystals were once thought to be too fragile for flexible applications, the UMass Amherst team found that crystals ranging in thickness from about 150 nanometers to 1 micrometer were thin enough to be wrinkled and applied to any elastomer substrate. Reyes-Martinez also notes, “Our experiments are especially important because they help scientists working on flexible electronic devices to determine performance limitations of new materials under extreme mechanical deformations, such as when electronic devices conform to skin.”

They developed an analytical model based on plate bending theoryto quantifythe different local strains imposed on the transistor structure by the wrinkle deformations. Using their model they are able to predict how different deformations modulate charge mobility, which no one had quantified before, Reyes-Martinez notes.

These contributions “represent a significant step forward in structure-function relationships in organic semiconductors, critical for the development of the next generation of flexible electronic devices,” the authors point out.

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

Rubrene crystal field-effect mobility modulation via conducting channel wrinkling by Marcos A. Reyes-Martinez, Alfred J. Crosby,  & Alejandro L. Briseno. Nature Communications 6, Article number: 6948 doi:10.1038/ncomms7948 Published 05 May 2015

This is an open access paper.

Are you sure my artificial muscles don’t smell like onions?

A May 5, 2015 news item on ScienceDaily highlights some research on artificial muscles from the National Taiwan University,

Just one well-placed slice into a particularly pungent onion can send even the most seasoned chef running for a box of tissues. Now, this humble root vegetable is proving its strength outside the culinary world as well — in an artificial muscle created from onion cells. Unlike previous artificial muscles, this one, created by a group of researchers from National Taiwan University, can either expand or contract to bend in different directions depending on the driving voltage applied.

A May 5, 2015 American Institute of Physics (AIP) news release by Laurel Hamers,  which originated the news item, describes the research goals,

“The initial goal was to develop an engineered microstructure in artificial muscles for increasing the actuation deformation [the amount the muscle can bend or stretch when triggered],” said lead researcher Wen-Pin Shih. “One day, we found that the onion’s cell structure and its dimensions were similar to what we had been making.” Shih lead the study along with graduate student Chien-Chun Chen and their colleagues.

The onion epidermis — the fragile skin found just beneath the onion’s surface — is a thin, translucent layer of blocky cells arranged in a tightly-packed lattice. Shih and his colleagues thought that onion epidermal cells might be a viable candidate for the tricky task of creating a more versatile muscle that could expand or contract while bending. To date, Shih said, artificial muscles can either bend or contract, but not at the same time.

The researchers treated the cells with acid to remove the hemicellulose, a protein that makes the cell walls rigid. Then, they coated both sides of the onion layer with gold. When current flowed through the gold electrodes, the onion cells bent and stretched much like a muscle.

“We intentionally made the top and bottom electrodes a different thickness so that the cell stiffness becomes asymmetric from top to bottom,” said Shih. The asymmetry gave the researchers control over the muscle’s response: a low voltage made them expand and flex downwards, towards the thicker bottom layer. A high voltage, on the other hand, caused the cells to contract and flex upwards, towards the thinner top layer.

“We found that the single-layer lattice structure can generate unique actuation modes that engineered artificial muscle has never achieved before,” said Shih.

To demonstrate their device’s utility, the researchers combined two onion muscles into a pair of tweezers, which they used to pick up a cotton ball. In the future, they hope to increase the lifting power of their artificial muscles. “Our next step is to reduce the driving voltage and the actuating force,” said Shih.

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

Onion artificial muscles by Chien-Chun Chen, Wen-Pin Shih, Pei-Zen Chang, Hsi-Mei Lai, Shing-Yun Chang, Pin-Chun Huang and Huai-An Jeng. Appl. Phys. Lett. 106, 183702 (2015); http://dx.doi.org/10.1063/1.4917498

This appears to be open access.

Gold and your neurons

Should you need any electrode implants for your neurons at some point in the future, it’s possible they could be coated with gold. Researchers at the Lawrence Livermore National Laboratory (LLNL) and at the University of California at Davis (UC Davis) have discovered that electrodes covered in nanoporous gold could prevent scarring (from a May 5, 2015 news item on Azonano),

A team of researchers from Lawrence Livermore and UC Davis have found that covering an implantable neural electrode with nanoporous gold could eliminate the risk of scar tissue forming over the electrode’s surface.

The team demonstrated that the nanostructure of nanoporous gold achieves close physical coupling of neurons by maintaining a high neuron-to-astrocyte surface coverage ratio. Close physical coupling between neurons and the electrode plays a crucial role in recording fidelity of neural electrical activity.

An April 30, 2015 LLNL news release, which originated the news item, details the scarring issue and offers more information about the proposed solution,

Neural interfaces (e.g., implantable electrodes or multiple-electrode arrays) have emerged as transformative tools to monitor and modify neural electrophysiology, both for fundamental studies of the nervous system, and to diagnose and treat neurological disorders. These interfaces require low electrical impedance to reduce background noise and close electrode-neuron coupling for enhanced recording fidelity.

Designing neural interfaces that maintain close physical coupling of neurons to an electrode surface remains a major challenge for both implantable and in vitro neural recording electrode arrays. An important obstacle in maintaining robust neuron-electrode coupling is the encapsulation of the electrode by scar tissue.

Typically, low-impedance nanostructured electrode coatings rely on chemical cues from pharmaceuticals or surface-immobilized peptides to suppress glial scar tissue formation over the electrode surface, which is an obstacle to reliable neuron−electrode coupling.

However, the team found that nanoporous gold, produced by an alloy corrosion process, is a promising candidate to reduce scar tissue formation on the electrode surface solely through topography by taking advantage of its tunable length scale.

“Our results show that nanoporous gold topography, not surface chemistry, reduces astrocyte surface coverage,” said Monika Biener, one of the LLNL authors of the paper.

Nanoporous gold has attracted significant interest for its use in electrochemical sensors, catalytic platforms, fundamental structure−property studies at the nanoscale and tunable drug release. It also features high effective surface area, tunable pore size, well-defined conjugate chemistry, high electrical conductivity and compatibility with traditional fabrication techniques.

“We found that nanoporous gold reduces scar coverage but also maintains high neuronal coverage in an in vitro neuron-glia co-culture model,” said Juergen Biener, the other LLNL author of the paper. “More broadly, the study demonstrates a novel surface for supporting neuronal cultures without the use of culture medium supplements to reduce scar overgrowth.”

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

Nanoporous Gold as a Neural Interface Coating: Effects of Topography, Surface Chemistry, and Feature Size by Christopher A. R. Chapman, Hao Chen, Marianna Stamou, Juergen Biener, Monika M. Biener, Pamela J. Lein, and Erkin Seker. ACS Appl. Mater. Interfaces, 2015, 7 (13), pp 7093–7100 DOI: 10.1021/acsami.5b00410 Publication Date (Web): February 23, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

The researchers have provided this image to illustrate their work,

The image depicts a neuronal network growing on a novel nanotextured gold electrode coating. The topographical cues presented by the coating preferentially favor spreading of neurons as opposed to scar tissue. This feature has the potential to enhance the performance of neural interfaces. Image by Ryan Chen/LLNL.

The image depicts a neuronal network growing on a novel nanotextured gold electrode coating. The topographical cues presented by the coating preferentially favor spreading of neurons as opposed to scar tissue. This feature has the potential to enhance the performance of neural interfaces. Image by Ryan Chen/LLNL.