Noninvasive Sensors For Brain–Machine Interfaces Based On Micropatterned Epitaxial Graphene

April 15, 2023 by Maya Posch 4 Comments

As fun as brain-computer interfaces (BCI) are, for the best results they tend to come with the major asterisk of requiring the cutting and lifting of a section of the skull in order to implant a Utah array or similar electrode system. A non-invasive alternative consists out of electrodes which are placed on the skin, yet at a reduced resolution. These electrodes are the subject of a recent experiment by [Shaikh Nayeem Faisal] and colleagues in ACS Applied NanoMaterials employing graphene-coated electrodes in an attempt to optimize their performance.

Impedance values of eight-channel FEG and eight-channel HPEG sensor systems placed on the occipital area of the head. (Faisal et al., 2023)

Although external electrodes can be acceptable for basic tasks, such as registering a response to a specific (visual) impulse or for EEG recordings, they can be impractical in general use. Much of this is due to the disadvantages of the ‘wet’ and ‘dry’ varieties, which as the name suggests involve an electrically conductive gel with the former.

This gel ensures solid contact and a resistance of no more than 5 – 30 kΩ at 50 Hz, whereas dry sensors perform rather poorly at >200 kΩ at 50 Hz with worse signal-to-noise characteristics, even before adding in issues such as using the sensor on a hairy scalp, as tends to be the case for most human subjects.

In this study, they created electrode arrays in a number of configurations, each of which used graphene as the interface material. The goal was to get a signal even through human hair — such as on the back of the head near the visual cortex — that would be on-par with wet electrodes. The researchers got very promising results with hex-patterned epitaxial graphene (HEPG) sensors, and even in this early prototype stage, the technique could offer an alternative where wet electrodes are not an option.

While the subject is complex, brain-computer interfaces don’t have to be the sole domain of research laboratories. We recently covered an open hardware Raspberry Pi add-on that can let you experiment with detecting and filtering biosignals from the comfort of your own home.

Uranium-241 Isotope Created And Examined Via Multinucleon Transfer Reactions And Mass Spectrometry

April 15, 2023 by Maya Posch 11 Comments

A recent paper (PDF) in Physical Review Letters by T. Niwase and colleagues covers a fascinating new way to both create and effectively examine isotopes by employing a cyclotron and a mass spectrograph. In the paper, they describe the process of multinucleon transfer (MNT) and analysis at the recently commissioned KEK Isotope Separation System (KISS), located at the RIKEN Nishina Center in Japan.

Sketch of the KISS experimental setup. The blue- and yellow-colored areas are filled with Ar and He gases, respectively. Differential pumping systems are located after the doughnut-shaped gas cell as well as before and after the GCCB. (Credit: Niwase et al., 2023) — Sketch of the KISS experimental setup. The blue- and
yellow-colored areas are filled with Ar and He gases, respectively. Differential pumping systems are located after the doughnut-shaped gas cell as well as before and after the GCCB. (Credit: Niwase et al., 2023)

The basic process which involves the RIKEN Ring Cyclotron, which was loaded for this particular experiment with Uranium-238 isotope. Over the course of four days, ²³⁸U particles impinged on a ¹⁹⁸Pt target, after which the resulting projectile-like fragments (PLF) were led through the separation system (see sketch). This prepared the thus created ions to be injected into the multi-reflection time-of-flight mass spectrograph (MRTOF MS), which is a newly installed and highly refined mass spectrograph which was also recently installed at the facility.

Using this method, the researchers were able to establish that during the MNT process in the cyclotron, the transfer of nucleons from the collisions had resulted in the production of ²⁴¹U as well as ²⁴²U. Although the former had not previously been produced in an experimental setting, the mass of ²⁴²U had not been accurately determined. During this experiment, the two uranium as well as neptunium and other isotopes were led through the MRTOF MS instrument, allowing for the accurate measurement of the characteristics of each isotope.

The relevance of producing new artificial isotopes of uranium lies not so much in the production of these, but rather in how producing these atoms allows us to experimentally confirm theoretical predictions and extrapolations from previous data. This may one day lead us to amazing discoveries such as the famously predicted island of stability, with superheavy, stable elements with as of yet unknown properties.

Even if such astounding discoveries are not in the future for theoretical particle physics, merely having another great tool like MNT to ease the burden of experimental verification would seem to be more than worth it.

The Challenges Of Producing Graphene In Quantity

April 12, 2023 by Maya Posch 26 Comments

We’ve all heard the incredible claims made about graphene and its many promising applications, but so far the wonder-material has been held back by the difficulty of producing it in large quantities. Although small-scale production was demonstrated many years ago using basic Scotch tape, producing grams or even kilograms of it in a scalable industrial process seemed like a pipedream — until recently. As [Tech Ingredients] demonstrates in a new video, the technique of flash Joule heating of carbon may enable industrial graphene production.

The production of this flash graphene (FG) was first demonstrated by Duy X. Luong and colleagues in a 2020 paper in Nature, which describes a fairly straightforward process. In the [Tech Ingredients] demonstration it becomes obvious how easy graphene manufacturing is using this method, requiring nothing more than carbon black as ingredient, along with a capacitor bank, vacuum chamber and a number of reasonably affordable items.

Perhaps best of all is that no refinement or other complicated processes are required to separate the produced graphene from the left-over carbon black and other non-graphene products. Using multiple of these carbon black-filled tubes in parallel, producing graphene could conceivably be scaled up to industrial levels. This would make producing a few kilograms of graphene significantly easier than coating hard drive platters with the substance.

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Using Old Coal Mines As Cheap Sources Of Geothermal Heat

April 11, 2023 by Maya Posch 33 Comments

For as much old coal mines are a blight upon the face of the Earth, they may have at least one potential positive side-effect. Where the coal mine consists out of tunnels that were drilled deep into the soil, these tend to get flooded by groundwater after the pumps that keep them dry are turned off. Depending on the surrounding rock, this water tends to get not only contaminated, but also warmed up. As the BBC explains in a recent video as a follow-up to a 2021 article, when the water is pumped up for decontamination, it can be run through a heat exchanger in order to provide heat for homes and businesses. Continue reading “Using Old Coal Mines As Cheap Sources Of Geothermal Heat” →

The UK’s ST40 Spherical Tokamak Achieves Crucial Plasma Temperatures

April 11, 2023 by Maya Posch 23 Comments

As the race towards the first commercially viable nuclear fusion reactor heats up, the UK-based Tokamak Energy has published a paper on its recent achievements with its ST40 spherical tokamak. Most notable is the achieving of plasma temperatures of over 100 million Kelvin, which would put this fusion reactor firmly within the range for deuterium-tritium fusion at a rate that would lead credence to the projection made by Tokamak Energy about building its first commercial fusion plants in the 2030s.

The ST40 is intended to provide the necessary data to construct the ST80-HTS by 2026, which itself would be a testing ground for the first commercial reactor, called the ST-E1, which would be rated at 200 MWe. Although this may seem ambitious, Tokamak Energy didn’t come out of nowhere, but is a spin-of of Culham Centre for Fusion Energy (CCFE), the UK’s national laboratory for fusion research, which was grounded in 1965, and has been for decades been involved in spherical tokamak research projects like MAST and MAST-Upgrade, with STEP as its own design for a commercial fusion reactor.

The advantage offered by spherical tokamaks compared to regular tokamaks is that they favor a very compact construction style which puts the magnets very close to the plasma, effectively making them more efficient in retaining the plasma, with less power required to maintain stable plasma. Although this makes the use of super-conducting electromagnets not necessary, it does mean that wear and tear on these magnets is significantly higher. What this does mean is that this type of tokamak can be much cheaper than alternative reactor types, even if they do not scale as well.

Whether or not Tokamak Energy will be the first to achieve commercial nuclear fusion remains to be seen. So far Commonwealth Fusion’s SPARC and a whole host of Western and Asian fusion projects are vying for that gold medal.

Busting Wireless ESD Wrist Straps With LTT And ElectroBOOM

April 10, 2023 by Maya Posch 28 Comments

Nobody likes getting zapped from an electrostatic discharge, no matter whether you’re a fragile ASIC or a bag-of-mostly-salty-water humanoid. To prevent this, ESD wrist straps and similar are essential tools, as they prevent the build-up of a charge on your humanoid’s skin, essentially like a very large electrolyte-filled capacitor. Yet you can buy wireless ESD straps everywhere that are supposed to somehow dissipate this charge into the ether, even though this would seem to undermine the laws of physics that make capacitors work.

In a practical experimentation and assorted hijinks video collaboration by [Linus] from Linus Tech Tips and [Mehdi Sadaghdar] from ElectroBOOM put these wireless ESD straps to the test, featuring [Mehdi]’s DIY Van de Graaff generator to charge [Linus] up. What is excellently demonstrated in this video is how effective a real ESD strap is, and how the ‘wireless’ version is just a scam that does absolutely nothing to dissipate the charge, being just a waste of a 1 MOhm resistor and what could have been a real ESD strap.

Also covered in the video are what the reason for the resistor in an ESD strap is, and why metal bracelet type ESD straps are not appropriate, for very good reasons.

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Supercon 2022: Aedan Cullen Is Creating An AR System To Beat The Big Boys

April 10, 2023 by Maya Posch 10 Comments

There’s something very tantalizing about an augmented reality (AR) overlay that can provide information in daily life without having to glance at a smartphone display, even if it’s just for that sci-fi vibe. Creating a system that is both practical and useful is however far from easy, which is where Aedan Cullen‘s attempt at creating what he terms a ‘practical augmented reality device’.

In terms of requirements, this device would need to have a visual resolution comparable to that of a smartphone (50 pixels/degree) and with a comparable field of view (20 degrees diagonal). User input would need to be as versatile as a touchscreen, but ‘faster’, along with a battery life of at least 8 hours, and all of this in a package weighing less than 50 grams.

Continue reading “Supercon 2022: Aedan Cullen Is Creating An AR System To Beat The Big Boys” →