Clotty The Custom Period Tracker Can, Of Course, Run DOOM

October 21, 2026 by Donald Papp 27 Comments

[kati]’s Clotty might run DOOM and game-ify the menstrual tracking process with a playful Tamagotchi-like aspect, but don’t let that distract you. It is, at its heart, a personal menstrual cycle tracking device that is defined as much by what it does do as what it doesn’t.

What doesn’t it do? Well, it will never quietly upload one’s menstrual tracking data to a remote server. Nor will it harvest, mishandle, disclose, or sell that same data. Shamefully, that alone sets it far apart from the wide range of period tracking services and apps out there. Also setting it apart is its cheerful lack of discretion. As [kati] puts it, she wanted Clotty’s design to scream “HELLO I AM A PERIOD TRACKING DEVICE” and at this she absolutely succeeded.

Clotty uses an RP2040, color LCD display, and a small variety of sensors built into a palm-sized, uterus-shaped PCB complete with touchpad ovaries. Right now it’s still in its early stages, and basically at the point that everything works hardware-wise and the essentials are there for software, but it’s still in active development. Keep an eye on Clotty’s GitHub repository for updates as features get fleshed out.

Of course, as [kati] observes, the core validity of a device can be defined by whether it can run DOOM, which of course Clotty can. You can find [kati]’s fork of RP2040-DOOM here.

[kati] has a knack for designing effective hardware that gamifies functions and incorporates a playfulness to the design that’s a delight to see. Take a moment to check out her Slightly Sentient D20 which is another excellent example of the kind of work she does.

3D printed jaw with fake muscle attached

3D Printing For The Hospital Setting

November 28, 2025 by Ian Bos 9 Comments

Surgery is hard, there is a reason why school is so long for the profession. Making the job easier and smoother for both patients and surgeons is valuable for all parties, which is why [Mayo Clinic] is now working on including 3D printing into its more regular medicine pipeline.

Prepping for surgery often requires examining CT scans of patients to figure out, well, what they’re even going to be doing. Every body is different, and complex surgical procedures require checking to see where certain organs or features are located. This can be made much easier with a physical model of where the bones, organs, or nerves are specifically located in a patient. While this isn’t true in every case of treatment, there are even cancerous cases where custom equipment can be used to decrease side effects, such as mini-beam collimator adapters.

What if you could use the same pipeline to print what was lost from certain procedures? In a mastectomy, the breast tissue is removed, which can cause negative attention from curious gazes. So why not 3D print a custom breast? Cases like these are generally considered poor commercial investments from industry, but are relatively easy for an existing medical facility to add to treatment.

[Mayo Clinic] is far from the first to consider 3D printing in the medical setting, but seeing the technology see actual applied use rather than future seeking is exciting. Medical hacking is always exciting, and if you want to see more examples, keep sure to check out this commercially available simulator (with some free models).

Supercon 2024: An Immersive Motion Rehabilitation Device

May 9, 2025 by Zoe Skyforest 1 Comment

When you’ve had some kind of injury, rehabilitation can be challenging. You often need to be careful about how you’re using the affected parts of your body, as well as pursue careful exercises for repair and restoration of function. It can be tedious and tiring work, for patients and treating practitioners alike.

Juan Diego Zambrano, Abdelrahman Farag, and Ivan Hernandez have been working on new technology to aid those going through this challenging process. Their talk at the 2024 Hackaday Supercon covers an innovative motion monitoring device intended to aid rehabilitation goals in a medical context.

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The Height Of 1960s Dental Electronic Technology

November 9, 2023 by Jenny List 9 Comments

If you’ve ever been to the dental surgery and found yourself requiring some gum surgery, the chances are you’ll have found your dentist wielding an electronic probe to cauterise the flesh. It’s evidently some form of RF device because you are usually required to hold one of the electrodes while it’s being used, but annoyingly, for an engineer, it’s hardly the time or place to ask how it works. For the curious, then, [Keri Szafir] has the box of tricks behind the probe and is subjecting it to a teardown.

The box on her bench isn’t the one you’ll find in your dentist’s toolkit today, but its distant ancestor from the 1960s that integrates multiple functions into a single box. It’s a very period enclosure with typically 1960s-style vacuum tubes and point-to-point wiring. There’s an HF oscillator using a pair of EL81 power pentodes for that electrode you always wished you could ask your dentist about, and unexpectedly, a thyratron, a type of gas-filled switching tube not dissimilar to a thyristor, in a separate circuit for dental pulp testing. We’re not dental experts here at Hackaday, but [Keri] has done the research and explains the device in the video below the break. At one point, she observes that it’s quite a scary machine to be connected to a living person, and we can concur with that.

Her bench has provided a few projects here in the past, including one of her amplifiers. While it might be fun to tear down a more modern version, you are better off asking for old dental burrs.

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Automatic Transfer Switch Keeps Internet Online

July 31, 2023 by Bryan Cockfield 48 Comments

Living in a place where the electric service isn’t particularly reliable can be frustrating, whether that’s because of a lack of infrastructure, frequent storms, or rolling blackouts. An option for those living in these situations is a backup generator, often turned on and connected by an automatic transfer switch. These are necessary safety devices too; they keep power lines from being back-fed by the generators. But there are other reasons to use transfer switches as well as [Maarten] shows us with this automatic transfer switch meant to keep his computers and Internet powered up.

The device is fairly straightforward. A dual-pole, dual-throw relay is housed inside of an electrical junction box with two electrical plugs, each of which can be connected to a different circuit or power source in [Maarten]’s house. The relay coil is energized by the primary power supply, and when that power is lost the relay automatically changes over to the other power supply, which might be something like a battery backup system. [Maarten] was able to get a higher quality product by building it himself rather than spending a comparable amount of money on a cheap off-the-shelf product as well. Continue reading “Automatic Transfer Switch Keeps Internet Online” →

Tuning Into Medical Implants With The RTL-SDR

July 11, 2021 by Tom Nardi 12 Comments

With a bit of luck, you’ll live your whole life without needing an implanted medical device. But if you do end up getting the news that your doctor will be installing an active transmitter inside your body, you might as well crack out the software defined radio (SDR) and see if you can’t decode its transmission like [James Wu] recently did.

Before the Medtronic Bravo Reflux Capsule was attached to his lower esophagus, [James] got a good look at a demo unit of the pencil-width gadget. Despite the medical technician telling him the device used a “Bluetooth-like” communications protocol to transmit his esophageal pH to a wearable receiver, the big 433 emblazoned on the hardware made him think it was worth taking a closer look at the documentation. Sure enough, its entry in the FCC database not only confirmed the radio transmitted a 433.92 MHz OOK-PWM encoded signal, but it even broke down the contents of each packet. If only it was always that easy, right?

The 433 ended up being a coincidence, but it got him on the right track.

Of course he still had to put this information into practice, so the next step was to craft a configuration file for the popular rtl_433 program which split each packet into its principle parts. This part of the write-up is particularly interesting for those who might be looking to pull data in from their own 433 MHz sensors, medical or otherwise

Unfortunately, there was still one piece of the puzzle missing. [James] knew which field was the pH value from the FCC database, but the 16-bit integer he was receiving didn’t make any sense. After some more research into the hardware, which uncovered another attempt at decoding the transmissions from the early days of the RTL-SDR project, he realized what he was actually seeing was the combination of two 8-bit pH measurements that are sent out simultaneously.

We were pleasantly surprised to see how much public information [James] was able to find about the Medtronic Bravo Reflux Capsule, but in a perfect world, this would be the norm. You deserve to know everything there is to know about a piece of electronics that’s going to be placed inside your body, but so far, the movement towards open hardware medical devices has struggled to gain much traction.

Building A Heavy Duty Open Source Ventilator

August 28, 2020 by Tom Nardi 12 Comments

Since the COVID-19 pandemic started, we’ve seen several attempts to create homebrew ventilators designed to address the shortage of these lifesaving machines. Unfortunately, most hackers aren’t terribly experienced when it comes to designing practical medical equipment. So while many of the designs might have appeared functional on the workbench, there’s little chance they’d get used in any official capacity.

The open source DP Ventilator is still clearly the product of a couple plucky hackers, but we think it shows a level of design maturity that’s been missing in many of the earlier attempts. Made primarily with 3D printed components, this mechanical device is designed to operate a hand-held manual resuscitator; essentially standing in for a human operator. This makes the design far less complex than if it had to actually pump air itself, not to mention safer for the patient since the resuscitator (often referred to as an Ambu Bag) installed in it would be a sterile pre-packaged item.

In the video after the break, you can see just how much thought and effort has been put into the device’s touch screen interface. With a few quick taps the medical professional operating the DP Ventilator can dial in variables such as breathing rate, pressure, and volume to match the patient’s needs. While the Arduino Mega 2560 at the machine’s heart wouldn’t pass muster for any regulating body in charge of medical devices, we think with a few more tweaks, this design is getting close to something that might actually be able to save lives.

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