Measuring Heart Rate With A Piezo

Look around for heart rate sensors that interface easily to microcontrollers, and you’ll come up with a few projects that use LEDs and other microcontrollers to do the dirty work of filtering out pulses in a wash of light.

[Thomas] was working on a project that detects if water is flowing through a pipe with a few piezoelectric sensors. Out of curiosity, he taped the sensor to his finger, and to everyone’s surprise, the values his microcontroller were spitting out were an extremely noise-free version of his heart rate.

The piezo in question is a standard, off the shelf module, and adding this to a microcontroller is as easy as putting the piezo on an analog pin. From there, it’s just averaging measurements and extracting a heartbeat from the data.

It’s a much simpler solution to measuring a heart rate, and since two people haven’t heard of this technique, it’s likely a lot more people haven’t heard of this technique either. If you’re looking for an entry to The Hackaday Prize, this would be a great jumping off point for anything in either the fitness or medical domains.

Brains Controlling Labyrinths Without Hands

[Daniel], [Gal] and [Maxim] attended a hackathon last weekend – Brainihack 2015 – that focused on neuroscience-themed builds in a day and a half long build off. The trio are communications systems engineering and computer science students with no background in neuroscience whatsoever. You can’t build an FMRI in a day and a half, so they ended up winning the best project in the open source category with a brain-controlled labyrinth game.

The labyrinth itself is entirely 3D printed and much, much simpler than the usual, ‘wooden maze with holes’ that’s generally associated with labyrinth puzzles. It’s really just a plastic spiral for a ball to follow. There’s a reason for this simplicity. The team is using EEG to detect brain waves and move the labyrinth on the X and Y axes.

The team is using OpenBCI for the interface between their brains and a pair of servos. This is actually an interesting piece of tech; unlike a few toys like the NeuroSky MindWave and the Star Wars Force Trainer, the OpenBCI gives you eight input channels that attach to anywhere on the scalp. The team used these inputs to measure Alpha waves and Steady State Visually Evoked Potential to control the pair of servos on the labyrinth frame.

It’s a great build, a wonderful demonstration of a device that outputs real EEG signals, and the team on a prize. What’s not to like?

2015 THP Inspiration: Medical Hacks

Last year’s Hackaday Prize focused on building something cool, useful, and open. This led to builds as impressive as quadcopters nicknamed the Decapitron, to devices as useful as an Everything Radio. It’s a big field, and if you want to build something that will win, you first need an idea.

This year we’re making that part of the process a little easier for you. We’re looking for builds that matter, be they devices that monitor pollution, feed entire populations, lay the groundwork for powering an entire city, or reduce the cost and increase access to medical care.

pillminderMedical builds are a tricky subject, but over the years we’ve seen a few that stand out. Some can be as simple as a pill dispenser that tells the Internet when you don’t take your meds. This type of build is actually pretty popular with several iterations, one that works with pill bottles.

Maybe a gadget you could find in a drug store isn’t your thing. That’s okay, instead you can turn your attention to advanced medical imaging, like 3D printing a brain tumor and preventing a misdiagnosis. We’ve seen 3D printed MRI and CT scans for a while now, and coming up with a system that automates the process would be a great entry for the Hackaday prize.

prosOf course with 3D printers, you have a bunch of prosthesis applications; from a nine-year-old who designed his own prosthetic arm, a printed prosthetic arm for a stranger, or something simpler like our own [Bil Herd]’s quest to rebuild a finger.

These are all simple builds, but ones that clearly meet the criteria of doing something meaningful. The sky is the limit, and if you want to improve the desktop CT scanner, learn CPR (correctly) from an automated assistant, or be brought back to life with your own design, that’s all well within the goals of this year’s Hackaday Prize.

Building a Transcutaneous Electrical Nerve Stimulation Device in a Weekend

Transcutaneous electrical nerve stimulation (TENS) is a technique that applies electrical current to nerves and muscles for the relief of pain. Before you ask, yes, some of these devices are FDA approved for various ailments. [Eric], [Conor], [Jacob], [lnr0626] and [rdrdrdrd] were down at HackDFW this weekend and built a TENS device from parts in their scrap bin.

A semi-decent TENS machine can cost somewhere between $70 and $200, but the team here have reduced the cost tremendously simply by separating the futzing analog/contact pad part from the signal generation part of the project. The signal generation actually happens on an Android phone, with settings to ‘relieve pain’, ‘relax’, ‘pulse’, and ‘random’. These signals are generated as audio and sent out over the headphone port. From there, the signal is amplified and sent to the neat skin-contact pads.

After prototyping their circuit, the team actually etched a circuit board for the final phase of the hackathon. Demo video below.

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Use the Force, Luke…to Turn Off Your TV

Have you ever wanted to turn on or off your TV just by thinking about it? We love this hack mainly because it uses an old Star Wars Force Trainer game. You can still buy them for about $40-$80 USD online. This cool little toy was introduced in 2009 and uses a headset with electrodes, and an electroencephalography (EEG) chip. It transmits the EEG data to control a fan that blows air into a tube to “levitate” a ball, all the while being coached on by the voice of Yoda. (Geesh! Kids these days have the best toys!)

[Tinkernut] started by cracking open the headset, where he found the EEG chip made by a company called NeuroSky (talk about a frightening sounding company name). The PCB designer was kind enough to label the Tx/Rx pins on the board, so hooking it up to an Arduino was a snap. After scavenging an IR LED and receiver from an old VCR, the hardware was just about done. After a bit of coding, you can now control your TV by using the force! (Ok, by ‘force’ I mean brainwaves.)  Video after the break.

Note: [Tinkernut’s] blog page should have more information available soon. In the meantime if you can find his Arduino Brain Library on github.

This isn’t the first EEG to TV interface we’ve featured. Way back in 2010 we featured a project that used an Emotiv EPOC EEG headset to turn on and off a TV. But at $400 for the headset, it was a little too expensive for the average Jedi.

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Store Digital Files for Eons in Silica-Encased DNA

If there’s one downside to digital storage, it’s the short lifespan.  Despite technology’s best efforts, digital storage beyond 50 years is extremely difficult. [Robert Grass, et al.], researchers from the Swiss Federal Institute of Technology in Zurich, decided to address the issue with DNA.  The same stuff that makes you “You” can also be used to store your entire library, and then some.

As the existence of cancer shows, DNA is not always replicated perfectly. A single mismatch, addition, or omission of a base pair can wreak havoc on an organism. [Grass, et al.] realized that for long-term storage capability, error-correction was necessary. They decided to use Reed-Solomon codes, which have been utilized in error-correction for many storage formats from CDs to QR codes to satellite communication. Starting with uncompressed digital text files of the Swiss Federal Charter from 1291 and the English translation of the Archimedes Palimpsest, they mapped every two bytes to three elements in a Galois field. Each element was then encoded to a specific codon, a triplet of nucleotides. In addition, two levels of redundancy were employed, creating outer- and inner- codes for error recovery. Since long DNA is very difficult to synthesize (and pricier), the final product was 4991 DNA segments of 158 nucleotides each (39 codons plus primers).

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Developer Saved Years Later by His Own Hardware

Bryan is a computer neophyte (he needs help turning his computer on), but he has a basketball story. His team was playing in a crucial basketball playoff game at the club. They were down by two late in the game and he just couldn’t get one of his players to play defense. This player was a great shooter and that is about it — burying a three that put the team up for the first time. After sinking it he just stood there admiring his masterpiece while Bryan screamed at him to get back on defense (he rarely played D and he didn’t that game either). Instead, he flat lined and went down on his face– heart attack!

Of course that player was me and that was an awful day. But I’m still around to tell the story… as a hardware designer years before I didn’t know that I’d bet everything on one particular project.

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