muscle

20 Articles

Electromyography

Electromyography Hack Chat

January 17, 2022 by No comments

Join us on Wednesday, January 19 at noon Pacific as we kick off the 2022 Hack Chat season with the Electromyography Hack Chat with hut!

It’s one of the simplest acts most people can perform, but just wiggling your finger is a vastly complex process under the hood. Once you consciously decide to move your digit, a cascade of electrochemical reactions courses from the brain down the spinal cord and along nerves to reach the muscles fibers of the forearm, where still more reactions occur to stimulate the muscle fibers and cause them to contract, setting that finger to wiggling.

join-hack-chatThe electrical activity going on inside you while you’re moving your muscles is actually strong enough to make it to the skin, and is detectable using electromyography, or EMG. But just because a signal exists doesn’t mean it’s trivial to make use of. Teasing a usable signal from one muscle group amidst the noise from everything else going on in a human body can be a chore, but not an insurmountable one, even for the home gamer.

To make EMG a little easier, our host for this Hack Chat, hut, has been hard at work on PsyLink, a line of prototype EMG interfaces that can be used to detect muscle movements and use them to control whatever you want. In this Hack Chat, we’ll dive into EMG in general and PsyLink in particular, and find out how to put our muscles to work for something other than wiggling our fingers.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, January 19 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

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Exoskeleton Muscles Powered By Hydrogen

October 21, 2020 by 19 Comments

The idea of building a suit that increases the wearer’s strength is a compelling one, often featured in science fiction. There are a handful of real world examples, and [Alex] can now add his to the list. The build comes with a twist however, relying on hydrogen to do the work.

At its heart, the build is not dissimilar to other artificial muscle projects. The muscles in [Alex’s] build consist of a rubber tube inside a nylon braid. When the rubber tube is inflated, it expands, causing the nylon braid to shorten as it grows wider. Commonly, such builds rely on compressed air to power the muscles, however [Alex] took a different path. Instead, water is electrolysed in a chamber designed to look like Iron Man’s arc reactor, with the resulting gases produced being used to drive the muscles. With five muscles ganged up to pull together, the wearable arm support is capable of generating up to 15 kg of pull force.

It’s a design that has a few benefits; the electrolyser has no moving parts, and is much simpler and quieter than a typical air compressor. Obviously, there is a risk of fire thanks to the flammable gases used, but [Alex] explains the precautions taken to minimise this risk in the video.

Exosuits may not be mainstream just yet, but that doesn’t mean people aren’t working to make them a reality. We’ve featured a few before, like this open-source design. Video after the break.

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Robot Insect Survives Swatting

December 23, 2019 by 4 Comments

There is an old saying, that ‘the hand is quicker than the eye;, but somewhat slower than the fly.” However, with a little practice you can swat a fly, although it sometimes doesn’t seem to faze the fly. École polytechnique fédérale de Lausanne (EPFL) has announced they have used nanotech to build a 1 gram possibly untethered, autonomous robotic insect that has enough processing power and sensors to recognize black and white patterns. Artificial muscles provide propulsion. But there’s the kicker: it can survive a strike with a fly swatter.

In the video you see below, the robots can move at 3 centimeters per second and there are two different versions. The first is a tethered system using ultra-thin wires. This is the version that can be folded, smacked, or even squashed by a shoe and continue moving.

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Muscle Your Way Into Music

May 28, 2018 by 6 Comments

Inspired by an old Old Spice commercial, [Juliodb96] decided he too wanted to make music by flexing his muscles. An Arduino and a MyoWare sensor did the trick. However, he also tells you how to make your own sensors, if you are so inclined. You can see the instrument in action in the video below.

If you use the ready-made MyoWare sensors, this is a pretty easy project. You just respond to sensor input by playing some notes. If you decide to roll your own, you’ll have some circuit building ahead of you.

In particular, the signal conditioning for the sensors involves filtering to eliminate signals not in the 20 Hz to 300 Hz passband, several amplifiers, a rectifier, and a clipper. This requires 3 IC packages and a handful of discrete components.

Unlike the original commercial (see the second video, below), there are no moving parts for actuating actual instruments. However, that wouldn’t be hard to add with some servo motors, air pumps, and the like. This may seem frivolous, but we had to wonder if it could be used to allow musical expression for people who could not otherwise play an instrument.

This isn’t the first time we’ve seen the MyoWare in action. We’ve even talked about signal processing that is useful for this kind of application.

A Flexible Sensor That Moves With You

July 29, 2017 by 6 Comments

If you have a project in mind that requires some sort of gesture input or precise movements, it might become a nettlesome problem to tackle. Fear this obstacle no longer: a team from the Wyss Institute for Biologically Inspired Engineering at Harvard have designed a novel way to make wearable sensors that can stretch and contort with the body’s natural movements.

The way they work is ingenious. Layers of silicone are sandwiched between two lengths of silver-plated conductive fabric forming — by some approximation — a capacitance sensor. While the total surface area doesn’t change when the sensor is stretched — how capacitance sensors normally work — it does bring the two layers of fabric closer together, changing the capacitance of the band in a proportional and measurable way, with the silicone pulling the sensor back into its original shape as tension relaxes. Wires can be attached to each end of the band with adhesive and a square of thermal film, making an ideal sensor to detect the subtlest of muscle movements.

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Genetically Engineered Muscle Cells Power Tiny Bio-Robots

February 18, 2017 by 8 Comments

One of the essential problems of bio-robotics is actuators. The rotors, bearings, and electrical elements of the stepper motors and other electromechanical drives we generally turn to for robotics projects are not really happy in living systems. But building actuators the way nature does it — from muscle tissue — opens up a host of applications. That’s where this complete how-to guide on building and controlling muscle-powered machines comes in.

Coming out of the [Rashid Bashir] lab at the University of Illinois at Urbana-Campaign, the underlying principles are simple, which of course is the key to their power. The technique involves growing rings of muscle tissue in culture using 3D-printed hydrogel as forms. The grown muscle rings are fitted on another 3D-printed structure, this one a skeleton with stiff legs on a flexible backbone. Stretched over the legs like rubber bands, the muscle rings can be made to contract and move the little bots around.

Previous incarnations of this technique relied on cultured rat heart muscle cells, which contract rhythmically of their own accord. That yielded motion but lacked control, so for this go-around, [Bashir] et al used skeletal muscle cells genetically engineered to contract when exposed to light. Illuminating different parts of the muscle ring lets the researchers move the bio-bots anywhere they want. They can also use electric stimulation to control the bio-bots.

The method isn’t quite at the point where home lab biohackers will start churning out armies of bio-bots. But the paper is remarkably detailed in methods and materials, from the CAD files for 3D-printing the forms and bio-bot skeletons to a complete troubleshooting guide. It’s all there, and it could be a game changer for developing the robotic surgeons of the future.

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Nylon Fibre Artificial Muscles — Powered By Lasers!

December 8, 2016 by 9 Comments

If only we had affordable artificial muscles, we might see rapid advances in prosthetic limbs, robots, exo-skeletons, implants, and more. With cost being one of the major barriers — in addition to replicating the marvel of our musculature that many of us take for granted — a workable solution seems a way off. A team of researchers at MIT present a potential answer to these problems by showing nylon fibres can be used as synthetic muscles.

Some polymer fibre materials have the curious property of increasing in  diameter while decreasing in length when heated. Taking advantage of this, the team at MIT were able to sculpt nylon fibre and — using a number of heat sources, namely lasers — could direct it to bend in a specific direction. More complex movement requires an array of heat sources which isn’t practical — yet — but seeing a nylon fibre dance tickles the imagination.

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