Stentrodes: A Way To Insert Brain Electrodes Without Invasive Surgery

When we think of brain-computer interfaces (BCIs) that use electrodes, we usually think of Utah arrays that are placed directly on the brain during open brain surgery, or with thin electrodes spliced into the exposed brain as postulated by Neuralink. While Utah arrays and kin as a practical concept date back to the 1980s, a more recent concept called Stentrodes – for stent-electrode array – seeks to do away with the need for invasive brain surgery.

As the name suggests, this approach uses stents that are inserted via the blood vessels, where they are expanded and thus firmly placed inside a blood vessel inside the brain. Since each of these stents also features an electrode array, these can be used to record neural activity in nearby neural clusters, as well as induce activity through electrical stimulation.

Due to the fact that stents are already commonly used by themselves in the brain’s blood vessels, and the relatively benign nature of these electrode arrays, human trials have already been approved in 2018 by an ethics committee in Australia. Despite lingering concerns about the achievable resolution and performance of this approach, it may offer hope to millions of people suffering from paralysis and other conditions.

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Liberated E-Ink Shelf Labels Turned 10×2 Display

How expensive is it to make a panel that uses e-ink technology? That might depend on how flexible you are. [RBarron] read about reverse engineering point-of-sale shelf labels and found them on eBay for just over a buck apiece. Next thing you know, 20 of them were working together in a single panel.

The panels use RF or NFC programming, normally, but have the capability to use BLE. Naturally you could just address each one in turn, but that isn’t very efficient. The approach here is to use one label as a BLE controller and it then drives the other displays in a serial daisy chain, where each label’s receive pin is set to the previous label’s transmit pin.

That allows a simple piece of code to read incoming messages and process the ones addressed to that label. Anything else just gets sent out the serial port. Only the BLE node has special firmware. At first, we thought each label would need an address and we wondered how it would be set other than having unique firmware for each one since there doesn’t appear to be a handy way to do a hardware-based configuration.

The actual solution is clever. Each message has a hop counter that each node decrements before passing the message along the chain. When the hop count is zero, the message is at its destination. Simple and very easy to configure. In theory, you could replace any of the labels after the first one with any other label and the system would still work correctly.

Even the wiring is clever, with a jig to bend the wire to ensure even spacing of each element on the panel. A laser-cut box finishes the project off nicely. The code is all available on GitHub. We’ve seen these kinds of tags used for things like weather stations. Not to mention conference badges.

3D Printed Braiding Machine Brings Back Some History

Mechanizing the production of textiles was a major part of the industrial revolution, and with the convenience of many people are recreating the classic machines. A perfect example of this is [Fraens]’ 3D printed braiding machine, which was reverse engineered from old photos of the early machines.

The trick behind braiding is the mesmerizing path the six bobbins need to weave around each other while maintaining the correct tension on the strands. To achieve this, they slide along a path in a guide plate while being passed between a series of guide gears for each section of the track. [Fraens] cut the guide plate components and the base plate below it from acrylic and mounted them together with standoffs to allow space for the guide gears.

Each of the six bobbins contains multiple parts to maintain the correct tension. The strands are fed through a single guide ring, where the braid is formed, and through pair of traction gears. All the moving parts are driven by a single 24 V motor and can produce about 42 cm of a braided cord per minute, and you can even set up the machine to braid around an inner core.

This braiding machine is just one in a series of early industrial machines recreated by [Fraens] using 3D printing. The others include a sewing machine, and a power loom, and a generator.

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