Genetically Engineered Muscle Cells Power Tiny Bio-Robots

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!

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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Zizzy The Personal Robot Uses 3D Printed Artificial Muscles Instead of Hobby Servos

Zizzy is a personal robot designed to help those with limited mobility. Rather than being assisted by a nightmare creature, Zizzy would offer a more appealing and friendly option.

The coolest part about Zizzy is the 3D printable pneumatic artificial muscles. Project creator, [Michael Roybal] said it took over a year of development to arrive at the design.

The muscles are hollow bellows printed out of Ninjaflex with carefully calibrated settings. A lot of work must have gone into the design to make sure that they were printable. After printing the muscles are painted with a mixture of fabric glue and MEK solvent. If all is done correctly the bellows should be able to hold 20 PSI without any problem.

This results in a robot with very smooth and precise movement. It has none of the gear noise and can also give when it collides with a user, a feature typically found only in very expensive motor systems. If [Michael] can find a quiet compressor system the robot will be nearly silent.

Tissue-Engineered Soft Robot Swims Like a Stingray

We’re about to enter a new age in robotics. Forget the servos, the microcontrollers, the H-bridges and the steppers. Start thinking in terms of optogenetically engineered myocytes, microfabricated gold endoskeletons, and hydrodynamically optimized elastomeric skins, because all of these have now come together in a tissue-engineered swimming robotic stingray that pushes the boundary between machine and life.

In a paper in Science, [Kevin Kit Parker] and his team at the fantastically named Wyss Institute for Biologically Inspired Engineering describe the achievement. It turns out that the batoid fishes like skates and rays have a pretty good handle on how to propel themselves in water with minimal musculoskeletal and neurological requirements, and so they’re great model organisms for a tissue engineered robot.

The body is a laminate of silicone rubber and a collection of 200,000 rat heart muscle cells. The cardiomyocytes provide the contractile force, and the pattern in which they are applied to the 1/2″ (1.25cm) body allows for the familiar undulating motion of a stingray’s wings. A gold endoskeleton with enough stiffness to act as a spring is used to counter the contraction of the muscle fibers and reset the system for another wave. Very clever stuff, but perhaps the coolest bit is that the muscle cells are genetically engineered to be photosensitive, making the robofish controllable with pulses of light. Check out the video below to see the robot swimming through an obstacle course.

This is obviously far from a finished product, but the possibilities are limitless with this level of engineering, especially with a system that draws energy from its environment like this one does. Just think about what could be accomplished if a microcontroller could be included in that gold skeleton.

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Hackaday Prize Semifinalist: Artificial Muscles and Supercapacitors

For [Lloyd T Cannon III]’s entry to the Hackaday Prize, he’s doing nothing less than changing the way everything moves. For the last 100 years, internal combustion engines have powered planes, trains, and automobiles, and only recently have people started looking at batteries and electric motors. With his supercapacitors and artificial muscles, [Lloyd] is a few decades ahead of everyone else.

There are two parts to [Lloyd]’s project, the first being the energy storage device. He’s building a Lithium Sulfur Silicon hybrid battery. Li-S-Si batteries have the promise to deliver up to 2000 Watt hours per kilogram of battery. For comparison, even advanced Lithium batteries top out around 2-300 Wh/kg. That’s nearly an order of magnitude difference, and while it’s a far way off from fossil fuels, it would vastly increase the range of electric vehicles and make many more technologies possible.

The other part of [Lloyd]’s project is artificial muscles. Engines aren’t terribly efficient, and electric motors are only good if you want to spin things. For robotics, muscles are needed, and [Lloyd] is building them out of fishing line. These muscles contract because of the resistive heating of a carbon fiber filament embedded in the muscle. It’s been done before, but this is the first project we’ve seen that replicates the technique in a garage lab.

Both parts of [Lloyd]’s project are worthy of a Hackaday Prize entry alone, but putting them together as one project more than meets the goal: to build something that matters.

The 2015 Hackaday Prize is sponsored by:

3D Printed Kinetic Art

Artificial muscles and soft robotics don’t get the respect they deserve, but [mikey77] is doing some very interesting work with artificial muscles that can be made on just about any 3D printer.

Like other artificial muscles and soft robotic actuators we’ve seen – like this walking sea slug and this eerie tentacle – [mikey77]’s muscles are powered by air. Instead of the usual casting method, he’s printing these muscles from Ninjaflex, a flexible plastic that is compatible with most 3D printers.

As they come off the printer, these 3D printed pneumatic muscles leak, and that means [mikey77] has to seal them. For that, he created a sealant out of Loctite fabric glue thinned with MEK. The addition of MEK dissolves the outer layer of Ninjaflex, allowing the glue to bond very, very well to the printed muscle.

So far, [mikey77] has created a pneumatic flower that blooms when air is added. He’s also created a muscle that can lift more than four pounds of weight with the help of a 3D printed skeleton. It’s a great way to experiment with flexible robots and pneumatic muscles, and we can’t wait to see what weird creatures can be created with these actuators.

Thanks [Lloyd] for sending this one in.

Artificial Muscles Use Carbon Nanotube Sheets

Light as air, stronger than steel and more flexible than rubber. Sound like something from the next installment of the Iron Man series? [Tony Stark] would certainly take notice of this fascinating technology. Fortunately for us, it does not come from the studios of Hollywood, but instead the halls of the NanoTech Institute at the University of Texas.

Professor [Ray Baughman] and his team of scientists at the NanoTech Institute have developed a type of artificial muscle through a process of making aerogel sheets by growing carbon nanotubes in a forest like structure. Think of a vertical bamboo forest, with each bamboo stem representing a single carbon nanotube. Now imagine that the individual bamboo stems were connected together by much smaller horizontal threads. So that if you dislodge the bamboo and began to pull, the threads would pull the others, and you would get this sheet-like structure.

These aerogel sheets of carbon nantubes have some truly science fiction like properties. They can operate from 1,600 degrees centigrade to near absolute zero. If you inject a charge, each nanotube will be repulsed from one another, expanding some 220% of the sheet’s original size. Your muscles do this at roughly 20 – 40%. Stick around after the break for a video demonstration of these carbon nanotube aerogel sheets being made and demonstrated.

Thanks to [Steven] for the tip!

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