Tag Archives: Skolkovo Institute of Science and Technology (Skoltech)

Compact and affordable brain-computer interface (BCI)

This device could help people with disabilities to regain control of their limbs or provide advance warnings of seizures to people with epilepsy and it’s all based on technology that is a century old.

A January 19, 2022 Skolkovo Institute of Science and Technology (Skoltech) press release (also on EurekAlert) provides details about the device (Note: A link has been removed),

Scientists from Skoltech, South Ural State University, and elsewhere have developed a device for recording brain activity that is more compact and affordable than the solutions currently on the market. With its high signal quality and customizable configuration, the device could help people with restricted mobility regain control of their limbs or provide advance warnings of an impending seizure to patients with epilepsy. The article presenting the device and testing results came out in Experimental Brain Research.

Researchers and medics, as well as engineers working on futuristic gadgets, need tools that measure brain activity. Among their scientific applications are research on sleep, decision-making, memory, and attention. In a clinical setting, these tools allow doctors to assess the extent of damage to an injured brain and monitor coma patients. Further down cyberpunk lane, brain signals can be translated into commands and sent to an external or implanted device, either to make up for lost functions in the body or for plain fun. The commands could range from moving the arm of an exoskeleton worn by a paralyzed person to turning on the TV.

Invented about a century ago, electroencephalographers are devices that read the electrical activity of the brain via small electrodes placed on the scalp. The recorded signals are then used for research, diagnostics, or gadgetry. The problem with the existing systems used in labs and hospitals is they are bulky and/or expensive. And even then, the number of electrodes is limited, resulting in moderate signal quality. Amateur devices tend to be more affordable, but with even poorer sensitivity.

To fill that gap, researchers from South Ural State University, North Carolina State University, and Brainflow — led by electronic research engineer Ildar Rakhmatulin and Skoltech neuroscientist Professor Mikhail Lebedev — created a device you can build for just $350, compared with the $1,000 or more you would need for currently available analogs. Besides being less expensive, the new electroencephalographer has as many as 24 electrodes or more. Importantly, it also provides research-grade signal quality. At half a centimeter in diameter (about 1/5 inches), the processing unit is compact enough to be worn throughout the day or during the night. The entire device weighs about 150 grams (about 5 ounces).

The researchers have made the instructions for building the device and the accompanying documentation and software openly available on GitHub. The team hopes this will attract more enthusiasts involved in brain-computer interface development, giving an impetus to support and rehabilitation system development, cognitive research, and pushing the geek community to come up with new futuristic gizmos.

“The more convenient and affordable such devices become, the more chances there are this would drive the home lab movement, with some of the research on brain-computer interfaces migrating from large science centers to small-scale amateur projects,” Lebedev said.

“Or we could see people with limited mobility using do-it-yourself interfaces to train, say, a smartphone-based system that would electrically stimulate a biceps to flex the arm at the elbow,” the researcher went on. “That works on someone who has lost control over their arm due to spinal cord trauma or a stroke, where the commands are still generated in the brain — they just don’t reach the limb, and that’s where our little brain-computer interfacing comes in.”

According to the team, such interfaces could also help patients with epilepsy by detecting tell-tale brain activity patterns that indicate when a seizure is imminent, so they can prepare by lying down comfortably in a safe space or attempting to suppress the seizure via electrical stimulation.

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

Low-cost brain computer interface for everyday use by Ildar Rakhmatulin, Andrey Parfenov, Zachary Traylor, Chang S. Nam & Mikhail Lebedev. Experimental Brain Research volume 239,Issue Date: December 2021, pages 3573–3583 (2021) DOI: https://doi.org/10.1007/s00221-021-06231-4 Published online: 29 September 2021

This paper is behind a paywall.

You can find Brainflow here and this description on its homepage: “BrainFlow is a library intended to obtain, parse and analyze EEG, EMG, ECG and other kinds of data from biosensors.”

New capacitor for better wearable electronics?

Supercapacitors are a predictable source of scientific interest and excitement. The latest entry in the ‘supercapacitor stakes’ is from a Russian/Finnish/US team according to a June 11, 2020 Skoltech (Skolkovo Institute of Science and Technology) press release (also on EurekAlert),

Researchers from Skoltech [Russia], Aalto University [Finland] and Massachusetts Institute of Technology [MIT; US] have designed a high-performance, low-cost, environmentally friendly, and stretchable supercapacitor that can potentially be used in wearable electronics. The paper was published in the Journal of Energy Storage.

Supercapacitors, with their high power density, fast charge-discharge rates, long cycle life, and cost-effectiveness, are a promising power source for everything from mobile and wearable electronics to electric vehicles. However, combining high energy density, safety, and eco-friendliness in one supercapacitor suitable for small devices has been rather challenging.

“Usually, organic solvents are used to increase the energy density. These are hazardous, not environmentally friendly, and they reduce the power density compared to aqueous electrolytes with higher conductivity,” says Professor Tanja Kallio from Aalto University, a co-author of the paper.

The researchers proposed a new design for a “green” and simple-to-fabricate supercapacitor. It consists of a solid-state material based on nitrogen-doped graphene flake electrodes distributed in the NaCl-containing hydrogel electrolyte. This structure is sandwiched between two single-walled carbon nanotube film current collectors, which provides stretchability. Hydrogel in the supercapacitor design enables compact packing and high energy density and allows them to use the environmentally friendly electrolyte.

The scientists managed to improve the volumetric capacitive performance, high energy density and power density for the prototype over analogous supercapacitors described in previous research. “We fabricated a prototype with unchanged performance under the 50% strain after a thousand stretching cycles. To ensure lower cost and better environmental performance, we used a NaCl-based electrolyte. Still the fabrication cost can be lowered down by implementation of 3D printing or other advanced fabrication techniques,” concluded Skoltech professor Albert Nasibulin.

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

Superior environmentally friendly stretchable supercapacitor based on nitrogen-doped graphene/hydrogel and single-walled carbon nanotubes by Evgeniia Gilshtein, Cristina Flox, Farhan S.M. Ali, Bahareh Mehrabimatin, Fedor S.Fedorov, Shaoting Lin, Xuanhe Zhao, Albert G. Nasibulin, Tanja Kallio. Journal of Energy Storage Volume 30, August 2020, 101505 DOI: https://doi.org/10.1016/j.est.2020.101505

This paper is behind a paywall.

I’m trying to remember if I’ve ever before seen a material that combines graphene and single-walled carbon nanotubes (SWCNTs). Anyway, here’s an image the researchers are using illustrate their work,

Caption: This is an outline of the new supercapacitor. Credit: Pavel Odinev / Skoltech

Deriving graphene-like films from salt

This research comes from Russia (mostly). A July 29, 2016 news item on ScienceDaily describes a graphene-like structure derived from salt,

Researchers from Moscow Institute of Physics and Technology (MIPT), Skolkovo Institute of Science and Technology (Skoltech), the Technological Institute for Superhard and Novel Carbon Materials (TISNCM), the National University of Science and Technology MISiS (Russia), and Rice University (USA) used computer simulations to find how thin a slab of salt has to be in order for it to break up into graphene-like layers. Based on the computer simulation, they derived the equation for the number of layers in a crystal that will produce ultrathin films with applications in nanoelectronics. …

Caption: Transition from a cubic arrangement into several hexagonal layers. Credit: authors of the study

Caption: Transition from a cubic arrangement into several hexagonal layers. Credit: authors of the study

A July 29, 2016 Moscow Institute of Physics and Technology press release on EurekAlert, which originated the news item,  provides more technical detail,

From 3D to 2D

Unique monoatomic thickness of graphene makes it an attractive and useful material. Its crystal lattice resembles a honeycombs, as the bonds between the constituent atoms form regular hexagons. Graphene is a single layer of a three-dimensional graphite crystal and its properties (as well as properties of any 2D crystal) are radically different from its 3D counterpart. Since the discovery of graphene, a large amount of research has been directed at new two-dimensional materials with intriguing properties. Ultrathin films have unusual properties that might be useful for applications such as nano- and microelectronics.

Previous theoretical studies suggested that films with a cubic structure and ionic bonding could spontaneously convert to a layered hexagonal graphitic structure in what is known as graphitisation. For some substances, this conversion has been experimentally observed. It was predicted that rock salt NaCl can be one of the compounds with graphitisation tendencies. Graphitisation of cubic compounds could produce new and promising structures for applications in nanoelectronics. However, no theory has been developed that would account for this process in the case of an arbitrary cubic compound and make predictions about its conversion into graphene-like salt layers.

For graphitisation to occur, the crystal layers need to be reduced along the main diagonal of the cubic structure. This will result in one crystal surface being made of sodium ions Na? and the other of chloride ions Cl?. It is important to note that positive and negative ions (i.e. Na? and Cl?)–and not neutral atoms–occupy the lattice points of the structure. This generates charges of opposite signs on the two surfaces. As long as the surfaces are remote from each other, all charges cancel out, and the salt slab shows a preference for a cubic structure. However, if the film is made sufficiently thin, this gives rise to a large dipole moment due to the opposite charges of the two crystal surfaces. The structure seeks to get rid of the dipole moment, which increases the energy of the system. To make the surfaces charge-neutral, the crystal undergoes a rearrangement of atoms.

Experiment vs model

To study how graphitisation tendencies vary depending on the compound, the researchers examined 16 binary compounds with the general formula AB, where A stands for one of the four alkali metals lithium Li, sodium Na, potassium K, and rubidium Rb. These are highly reactive elements found in Group 1 of the periodic table. The B in the formula stands for any of the four halogens fluorine F, chlorine Cl, bromine Br, and iodine I. These elements are in Group 17 of the periodic table and readily react with alkali metals.

All compounds in this study come in a number of different structures, also known as crystal lattices or phases. If atmospheric pressure is increased to 300,000 times its normal value, an another phase (B2) of NaCl (represented by the yellow portion of the diagram) becomes more stable, effecting a change in the crystal lattice. To test their choice of methods and parameters, the researchers simulated two crystal lattices and calculated the pressure that corresponds to the phase transition between them. Their predictions agree with experimental data.

Just how thin should it be?

The compounds within the scope of this study can all have a hexagonal, “graphitic”, G phase (the red in the diagram) that is unstable in 3D bulk but becomes the most stable structure for ultrathin (2D or quasi-2D) films. The researchers identified the relationship between the surface energy of a film and the number of layers in it for both cubic and hexagonal structures. They graphed this relationship by plotting two lines with different slopes for each of the compounds studied. Each pair of lines associated with one compound has a common point that corresponds to the critical slab thickness that makes conversion from a cubic to a hexagonal structure energetically favourable. For example, the critical number of layers was found to be close to 11 for all sodium salts and between 19 and 27 for lithium salts.

Based on this data, the researchers established a relationship between the critical number of layers and two parameters that determine the strength of the ionic bonds in various compounds. The first parameter indicates the size of an ion of a given metal–its ionic radius. The second parameter is called electronegativity and is a measure of the ? atom’s ability to attract the electrons of element B. Higher electronegativity means more powerful attraction of electrons by the atom, a more pronounced ionic nature of the bond, a larger surface dipole, and a lower critical slab thickness.

And there’s more

Pavel Sorokin, Dr. habil., [sic] is head of the Laboratory of New Materials Simulation at TISNCM. He explains the importance of the study, ‘This work has already attracted our colleagues from Israel and Japan. If they confirm our findings experimentally, this phenomenon [of graphitisation] will provide a viable route to the synthesis of ultrathin films with potential applications in nanoelectronics.’

The scientists intend to broaden the scope of their studies by examining other compounds. They believe that ultrathin films of different composition might also undergo spontaneous graphitisation, yielding new layered structures with properties that are even more intriguing.

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

Ionic Graphitization of Ultrathin Films of Ionic Compounds by A. G. Kvashnin, E. Y. Pashkin, B. I. Yakobson, and P. B. Sorokin. J. Phys. Chem. Lett., 2016, 7 (14), pp 2659–2663 DOI: 10.1021/acs.jpclett.6b01214 Publication Date (Web): June 23, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.