Better Living Through Biomedical Engineering

February 9, 2024 by Tom Nardi 3 Comments

We don’t often think of medicine and engineering as being related concepts, and most of the time, they aren’t. But there’s a point where medicine alone may not be enough to treat a particular ailment or injury, and it might be necessary to blend the mechanical with the biological. When a limb is lost, we don’t have the technology to regrow it, but we can apply engineering principles to build a functional facsimile that can help the patient regain lost independence and improve their quality of life.

The area where these two disciplines overlap is called biomedical engineering (BME), and it’s a field that’s seeing fantastic growth thanks to advances in 3D printing, materials science, and machine learning. It’s also a field where open source principles and DIY are making surprising inroads, as hobbyists look to put their own knowledge and experience to use by creating low-cost assistive devices — something we were honored to help facilitate over the years through the Hackaday Prize.

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Hackaday Prize 2023: Finger Tracking Via Muscle Sensors

May 12, 2023 by Lewin Day 5 Comments

Whether you want to build a computer interface device, or control a prosthetic hand, having some idea of a user’s finger movements can be useful. The OpenMuscle finger tracking sensor can offer the data you need, and it’s a device you can readily build in your own workshop.

The device consists of a wrist cuff that mounts twelve pressure sensors, arranged radially about the forearm. The pressure sensors are a custom design, using magnets, hall effect senors, and springs to detect the motion of the muscles in the vicinity of the wrist.

We first looked at this project last year, and since then, it’s advanced in leaps and bounds. The basic data from the pressure sensors now feeds into a trained machine learning model, which then predicts the user’s actual finger movements. The long-term goal is to create a device that can control prosthetic hands based on muscle contractions in the forearm. Ideally, this would be super-intuitive to use, requiring a minimum of practice and training for the end user.

It’s great to see machine learning combined with innovative mechanical design to serve a real need. We can’t wait to see where the OpenMuscle project goes next.

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A cinematic shot of the resulting prosthetic finger attached to the glove

Missing Finger Gets A Simple Yet Fancy Replacement

March 3, 2023 by Arya Voronova 27 Comments

The possibility of a table saw accident is low, but never zero — and [Nerdforge] has lost a finger to this ever-useful but dangerous contraption. For a right-handed person, losing the left hand pinky might not sound like much, but the incident involved some nerve damage as well, making inaccessible a range of everyday motions we take for granted. For instance, holding a smartphone or a pile of small objects without dropping them. As a hacker, [Nerdforge] decided to investigate just how much she could do about it.

On Thingiverse, she’s hit a jackpot: a parametric prosthetic finger project by [Nicholas Brookins], and in no time, printed the first version in resin. The mechanics of the project are impressive in their simplicity — when you close your hand, the finger closes too. Meant to be as simple as possible, this project only requires a wrist mount and some fishing line. From there, what could she improve upon? Aside from some test fits, the new finger could use a better mounting system, it could stand looking better, and of course, it could use some lights.

For a start, [Nerdforge] redesigned the mount so that the finger would instead fasten onto a newly-fingerless glove, with a few plastic parts attached into that. Those plastic parts turned out to be a perfect spot for a CR2032 battery holder and a microswitch, wired up to a piece of LED filament inserted into the tip of the finger. As for the looks, some metal-finish paint was found to work wonders – moving the glove’s exterior from the “printed project” territory into the “futuristic movie prop” area.

The finger turned out to be a resounding success, restoring the ability to hold small objects in ways that the accident made cumbersome. It doesn’t provide much in terms of mechanical strength, but it wasn’t meant to do that. Now, [Nerdforge] has hacked back some of her hand’s features, and we have yet another success story for all the finger-deficient hackers among us. Hacker-built prosthetics have been a staple of Hackaday, with the OpenBionics project in particular being a highlight of 2015 Hackaday Prize — an endearing demonstration of hackers’ resilience.

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A Bargain In Bionic Knees

April 8, 2022 by Al Williams 17 Comments

You probably don’t want to lose a leg, but if you have to there are many options now that were unthinkable not long ago. That is, if you can afford them. A microprocessor knee — a prosthetic with some smarts in it — can run anywhere from $25,000 to well over $100,000. However [Lucas Galey], a PhD candidate at the University of Texas El Paso in a recent paper claims to be able to produce a comparable artificial knee for under $1,000. If the paper is too long to read, Amplitude has a good summary including what it means to people who need them.

Of course, the cost of making something like this is almost incidental. The cost of approvals, testing, and other factors mean that even with about $500 in parts, the retail price would be much higher. Probably not $25,000, though.

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Hackaday Links: May 2, 2021

May 2, 2021 by Dan Maloney 3 Comments

Mars is getting to be a busy place, what with helicopters buzzing around and rovers roving all about the place. Now it’s set to get a bit more crowded, with the planned descent of the newly-named Chinese Zhurong rover. Named after the god of fire from ancient Chinese mythology, the rover, which looks a little like Opportunity and Spirit and rides to the surface aboard something looking a little like the Viking lander, will carry a suite of scientific instruments around Utopia Planitia after it lands sometime this month. Details are vague; China usually plays its cards close to the vest, and generally makes announcements only when a mission is a fait accompli. But it appears the lander will leave its parking orbit, which it entered back in February, sometime this month. It’s not an easy ride, and we wish Zhurong well.

Speaking of space, satellites don’t exactly grow on trees — until they do. A few groups, including a collaboration between UPM Plywood and Finnish startup Arctic Astronautics, have announced intentions to launch nanosatellites made primarily of wood. Japanese logging company Sumitomo Forestry and Kyoto University also announced their partnership, formed with the intention to prove that wooden satellites can work. While it doesn’t exactly spring to mind as a space-age material, wood does offer certain advantages, including relative transparency to a wide range of the RF spectrum. This could potentially lead to sleeker satellite designs, since antennae and sensors could be located inside the hull. Wood also poses less of a hazard than a metal spaceframe does when the spacecraft re-enters the atmosphere. But there’s one serious disadvantage that we can see: given the soaring prices for lumber, at least here in the United States, it may soon be cheaper to build satellites out of solid titanium than wood.

If the name Ian Davis doesn’t ring a bell with you, one look at his amazing mechanical prosthetic hand will remind you that we’ve been following his work for a while now. Ian suffered a traumatic amputation of the fingers of his left hand, leaving only his thumb and palm intact, and when his insurance wouldn’t pay for a prosthetic hand, he made his own. Ian has gone through several generations, each of which is completely mechanical and controlled only by wrist movements. The hands are truly works of mechanical genius, and Ian is now sharing what he’s learned to help out fellow hand-builders. Even if you’re not building a hand, the video is well worth watching; the intricacy of the whiffle-tree mechanism used to move the fingers is just a joy to behold, and the complexity of movement that Ian’s hand is capable of is just breathtaking.

If mechanical hands don’t spark your interest, then perhaps the engineering behind top fuel dragsters will get you going. We’ll admit that most motorsports bore us to tears, even with the benefit of in-car cameras. But there’s just something about drag cars that’s so exciting. The linked video is a great dive into the details of the sport, where engines that have to be rebuilt after just a few seconds use, fuel flows are so high that fuel lines the size of a firehouse are used, and the thrust from the engine’s exhaust actually contributes to the car’s speed. There’s plenty of slo-mo footage in the video, including great shots of what happens to the rear tires when the engine revs up. Click through the break for more!

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A Gesture Recognizing Armband

January 2, 2021 by Danie Conradie 4 Comments

Gesture recognition usually involves some sort of optical system watching your hands, but researchers at UC Berkeley took a different approach. Instead they are monitoring the electrical signals in the forearm that control the muscles, and creating a machine learning model to recognize hand gestures.

The sensor system is a flexible PET armband with 64 electrodes screen printed onto it in silver conductive ink, attached to a standalone AI processing module. Since everyone’s arm is slightly different, the system needs to be trained for a specific user, but that also means that the specific electrical signals don’t have to be isolated as it learns to recognize patterns.

The challenging part of this is that the patterns don’t remain constant over time, and will change depending on factors such as sweat, arm position, and even just biological changes. To deal with this the model can update itself on the device over time as the signal changes. Another part of this research that we appreciate is that all the inferencing, training, and updating happens locally on the AI chip in the armband. There is no need to send data to an external device or the “cloud” for processing, updating, or third-party data mining. Unfortunately the research paper with all the details is behind a paywall.

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Meticulous Bionic Hand

November 12, 2020 by Matthew Carlson 12 Comments

[Will Cogley] is slowly but surely crafting a beautiful bionic hand. (Video, embedded below.) The sheer amount of engineering and thought that went into the design is incredible. Those who take their hands for granted often don’t consider the different ways that their digits can move. There is lateral movement, rotation, flexion, and extension. Generally, [Will] tries to design mechanisms with parts that can be 3D printed or sourced easily. This constrains the hand to things like servos, cable actuation, or direct drive.

However, the thumb has a particularly tricky range of motion. So for the thumb [Will] designed to use a worm geared approach to produce the flexing and extension motion of the thumb. These gears need to be machined in order to stand up to the load. A small side 3d printed gear that connects to the main worm gear is connected to a potentiometer to form the feedback loop. Since it isn’t bearing any load, it can be 3d printed. While there are hundreds of little tiny problems still left to fix, the big problems left are wire management, finalizing the IP (Interphalangeal) joints, and attaching the whole assembly to the forearm.

All the step files, significants amounts of research, and definitions are all on [Will’s] GitHub. If you’re looking into creating any sort of hand prosthetic, the research and attention [Will] has put into this is work incorporating into your project. We’ve seen bionic hands before as well as aluminum finger replacements, but this is a whole hand with fantastic range and fidelity.

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