Category Archives: protection

Artificial muscles using folded graphene

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Folded Graphene Concept

Two years ago I wrote a blog on future hosiery where I very briefly mentioned the idea of using folded graphene as synthetic muscles:

https://timeguide.wordpress.com/2015/11/16/the-future-of-nylon-ladder-free-hosiery/

Although I’ve since mentioned it to dozens of journalists, none have picked up on it, so now that soft robotics and artificial muscles are in the news, I guess it’s about time I wrote it up myself, before someone else claims the idea. I don’t want to see an MIT article about how they have just invented it.

The above pic gives the general idea. Graphene comes in insulating or conductive forms, so it will be possible to make sheets covered with tiny conducting graphene electromagnet coils that can be switched individually to either polarity and generate strong magnetic forces that pull or push as required. That makes it ideal for a synthetic muscle, given the potential scale. With 1.5nm-thick layers that could be anything from sub-micron up to metres wide, this will allow thin fibres and yarns to make muscles or shape change fabrics all the way up to springs or cherry-picker style platforms, using many such structures. Current can be switched on and off or reversed very rapidly, to make continuous forces or vibrations, with frequency response depending on application – engineering can use whatever scales are needed. Natural muscles are limited to 250Hz, but graphene synthetic muscles should be able to go to MHz.

Uses vary from high-rise rescue, through construction and maintenance, to space launch. Since the forces are entirely electromagnetic, they could be switched very rapidly to respond to any buckling, offering high stabilisation.

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The extreme difference in dimensions between folded and opened state mean that an extremely thin force mat made up of many of these cherry-picker structures could be made to fill almost any space and apply force to it. One application that springs to mind is rescues, such as after earthquakes have caused buildings to collapse. A sheet could quickly apply pressure to prize apart pieces of rubble regardless of size and orientation. It could alternatively be used for systems for rescuing people from tall buildings, fracking or many other applications.

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It would be possible to make large membranes for a wide variety of purposes that can change shape and thickness at any point, very rapidly.

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One such use is a ‘jellyfish’, complete with stinging cells that could travel around in even very thin atmospheres all by itself. Upper surfaces could harvest solar power to power compression waves that create thrust. This offers use for space exploration on other planets, but also has uses on Earth of course, from surveillance and power generation, through missile defense systems or self-positioning parachutes that may be used for my other invention, the Pythagoras Sling. That allows a totally rocket-free space launch capability with rapid re-use.

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Much thinner membranes are also possible, as shown here, especially suited for rapid deployment missile defense systems:

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Also particularly suited to space exploration o other planets or moons, is the worm, often cited for such purposes. This could easily be constructed using folded graphene, and again for rescue or military use, could come with assorted tools or lethal weapons built in.

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A larger scale cherry-picker style build could make ejector seats, elevation platforms or winches, either pushing or pulling a payload – each has its merits for particular types of application.  Expansion or contraction could be extremely rapid.

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An extreme form for space launch is the zip-winch, below. With many layers just 1.5nm thick, expanding to 20cm for each such layer, a 1000km winch cable could accelerate a payload rapidly as it compresses to just 7.5mm thick!

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Very many more configurations and uses are feasible of course, this blog just gives a few ideas. I’ll finish with a highlight I didn’t have time to draw up yet: small particles could be made housing a short length of folded graphene. Since individual magnets can be addressed and controlled, that enables magnetic powders with particles that can change both their shape and the magnetism of individual coils. Precision magnetic fields is one application, shape changing magnets another. The most exciting though is that this allows a whole new engineering field, mixing hydraulics with precision magnetics and shape changing. The powder can even create its own chambers, pistons, pumps and so on. Electromagnetic thrusters for ships are already out there, and those same thrust mechanisms could be used to manipulate powder particles too, but this allows for completely dry hydraulics, with particles that can individually behave actively or  passively.

Fun!

 

 

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Spiderman-style silk thrower

I quite like Spiderman movies, and having the ability to fire a web at a distant object or villain has its appeal. Since he fires web from his forearm, it must be lightweight to withstand the recoil, and to fire enough to hold his weight while he swings, it would need to have extremely strong fibers. It is therefore pretty obvious that the material of choice when we build such a thing will be graphene, which is even stronger than spider silk (though I suppose a chemical ejection device making spider silk might work too). A thin graphene thread is sufficient to hold him as he swings so it could fit inside a manageable capsule.

So how to eject it?

One way I suggested for making graphene threads is to 3D print the graphene, using print nozzles made of carbon nanotubes and using a very high-speed modulation to spread the atoms at precise spacing so they emerge in the right physical patterns and attach appropriate positive or negative charge to each atom as they emerge from the nozzles so that they are thrown together to make them bond into graphene. This illustration tries to show the idea looking at the nozzles end on, but shows only a part of the array:printing graphene filamentsIt doesn’t show properly that the nozzles are at angles to each other and the atoms are ejected in precise phased patterns, but they need to be, since the atoms are too far apart to form graphene otherwise so they need to eject at the right speed in the right directions with the right charges at the right times and if all that is done correctly then a graphene filament would result. The nozzle arrangements, geometry and carbon atom sizes dictate that only narrow filaments of graphene can be produced by each nozzle, but as the threads from many nozzles are intertwined as they emerge from the spinneret, so a graphene thread would be produced made from many filaments. Nevertheless, it is possible to arrange carbon nanotubes in such a way and at the right angle, so provided we can get the high-speed modulation and spacing right, it ought to be feasible. Not easy, but possible. Then again, Spiderman isn’t real yet either.

The ejection device would therefore be a specially fabricated 3D print head maybe a square centimeter in area, backed by a capsule containing finely powdered graphite that could be vaporized to make the carbon atom stream through the nozzles. Some nice lasers might be good there, and some cool looking electronic add-ons to do the phasing and charging. You could make this into one heck of a cool gun.

How thick a thread do we need?

Assuming a 70kg (154lb) man and 2g acceleration during the swing, we need at least 150kg breaking strain to have a small safety margin, bearing in mind that if it breaks, you can fire a new thread. Steel can achieve that with 1.5mm thick wire, but graphene’s tensile strength is 300 times better than steel so 0.06mm is thick enough. 60 microns, or to put it another way, roughly 140 denier, although that is a very quick guess. That means roughly the same sort of graphene thread thickness is needed to support our Spiderman as the nylon used to make your backpack. It also means you could eject well over 10km of thread from a 200g capsule, plenty. Happy to revise my numbers if you have better ones. Google can be a pain!

How fast could the thread be ejected?

Let’s face it. If it can only manage 5cm/s, it is as much use as a chocolate flamethrower. Each bond in graphene is 1.4 angstroms long, so a graphene hexagon is about 0.2nm wide. We would want our graphene filament to eject at around 100m/s, about the speed of a crossbow bolt. 100m/s = 5 x 10^11 carbon atoms ejected per second from each nozzle, in staggered phasing. So, half a terahertz. Easy! That’s well within everyday electronics domains. Phew! If we can do better, we can shoot even faster.

We could therefore soon have a graphene filament ejection device that behaves much like Spiderman’s silk throwers. It needs some better engineers than me to build it, but there are plenty of them around.

Having such a device would be fun for sports, allowing climbers to climb vertical rock faces and overhangs quickly, or to make daring leaps and hope the device works to save them from certain death. It would also have military and police uses. It might even have uses in road accident prevention, yanking pedestrians away from danger or tethering cars instantly to slow them extra quickly. In fact, all the emergency services would have uses for such devices and it could reduce accidents and deaths. I feel confident that Spiderman would think of many more exciting uses too.

Producing graphene silk at 100m/s might also be pretty useful in just about every other manufacturing industry. With ultra-fine yarns with high strength produced at those speeds, it could revolutionize the fashion industry too.

Carbon fur: biokleptic warmth and protection

Some women would rather die than kill an animal to steal its fur, but we can steal ideas from nature without harming anyone or anything. That’s normally called biomimetics but really it should be called bio-kleptics. People call it biomimetics because they want to pretend it isn’t stealing but ‘only copying’, as if nature shouldn’t be entitled to any intellectual property protection. Then again, imitation is a form of flattery, and we are ourselves part of nature, so maybe we have inheritance-based rights to copy whatever we see. So let’s not make a big deal of it.

Fur is a great idea. Millions of long fine strands of material are extruded from the base to make a dense but very soft material that traps air to keep the animal warm, give some protection from sun and scratches by thorns, and make it harder to eat. If it’s dense enough, or coated with oil, also preventing water from getting through. If it looks right, it also makes the animal cute to humans, so they’re less likely to murder it and may even sponsor it as a pet, with free accommodation, medicare and food.

So… carbon fur. Well, obviously it would be based either on nanotubes, or graphene strands, or some combo. Both can make long hollow fibres (aha! there’s their duvet and pillows sorted for a future blog) so are perfect to make fur. Conventional synthetic fur coat manufacturers have already got perfectly good techniques for making fur, so if I was lazy, I could just use them. But the Carbon Trio need something special. And they really are fond of nature, so we need some technique that allows the carbon skin to self organise into follicles and extrude fur filaments from there. And it just so happens, I made one earlier.

Self-organisation is the sound basis of a huge multitude of natural phenomena. Even human life starts as a single cell, and after some divisions the cells have to start differentiating and self-organising into structures that become limbs or organs or whatever. When I was asked to study DNA as a computing basis in 1992, I got sidetracked when I was reading up on cell differentiation and realised that the same principle could be used to self organise electronic systems such as exchanges, chips, circuits and even processors. A few years later, another BT engineer, whose name I have sadly forgotten, adapted similar self-organisation principles involved in hair growth on a fruit fly’s abdomen to make a mechanism for self organising mobile phone networks. Both of us independently used nature’s idea of hormone gradients. It works well, both in nature and in engineering. Given nature’s other idea of membranes, and linking the two,very complex systems can be self organised. So that’s the basis of how carbon filaments in carbon fur arrange themselves so that they’re nicely spread out without having to manually place every single one. Each follicle would be a tiny graphene strand printer/extruder, and the follicles would self-organise using virtual hormone gradients and membranes. In practice these virtual hormone gradients can be magnetic or electric fields, chemical gradients, signal strengths or any other physical property that can be varied. Membranes can be digitally demarked by naming or use physical  interference effects or barriers.

So what about extrusion? Well, that’s easy enough too, easy enough when you only have to do something on paper anyway. Here:

printing graphene

Imagine a 3D printer with a head that is a packed array of carbon-atom-emitting tubes. It could be made with a nice hexagonal layout as in the picture above, simply by aligning many layers of graphene on top of each other. 6 carbon atoms in a hexagon just make room for a 7th to come through the centre. If that doesn’t work because it is too tight a fit, carbon nanotubes can be made to size to do the job. I’ve only drawn a small section of the head for simplicity. This diagram only shows the print face, not the 3D structure.

In the diagram above, each vertex is a carbon atom. (The colours are only to clarify the diagram, the vertices that are shared are just one atom, not two). If carbon atoms are forced through the centres of the hexagons in the ‘bit pattern’ shown on the right, driven by a high frequency and perfectly phased signal, graphene would come out of the printer. Bear with me here.

I haven’t got the diagram wrong. The trouble at first glance is that the distances between the centres obviously isn’t the same as the length of each side of the hexagon, so the hexagonal pattern of atoms streaming out won’t be the same dimension as the graphene used to make the print head. That isn’t a problem here.

With this technique, it would not be able to make large continuous sheets of graphene, but by phasing the emissions of each pipe, what it could do is to produce thin strands of graphene, and a range of widths of strand would be feasible. The phasing is all-important, as it would drive the production of the strand around the print head as it emerges.The carbon atoms would converge and bond as they emerge if the ionisation and phasing is correct. Phasing would need waves of EM field to pass through the graphene, originating from transmitters on the circumference. Ionisation of the carbon atoms would be before they enter the tubes, and although they would be sucked into the tubes in a continuous stream, their bit pattern emerges as they are spread out selectively by the fields acting on them. As I said, phasing is all important.

Each print head would produce one strand of graphene. The strand would be very fine. With clusters of these print heads extruding strands of graphene, you would get graphene fur. Rubbish if you want sheet, but great if you want fur. So there we are. Just as Post-it glue was accidentally found while trying to design something else, poor design for a graphene sheet printer turns out to be just what we need to make carbon fur. Spacing the print heads to the required pattern, any density of carbon fur is possible from sparse to dense.

The fur filaments would emerge from the graphene layers that make up the print heads, and these would not be continuous, but attached to an under-layer in patches so that they can stay in place. Using a different attachment pattern for each layer of print head allows great strength and maintains alignment. This under-layer provides the solid foundation and material strength. It could use combinations of graphene, nanotubes and mostly carbon fibre, together with the fur itself.

OK, it looks OK in theory, even if I haven’t bothered explaining every detail, but this would be difficult to do, so puts this kind of technology a bit further in the future than a lot of other carbon products.

Carbon fur also makes good protection and insulation.

Biomimetic fabrics and carbon fur will feature in some later blogs too. And the printer here is capable of very fine print, and very intricate 3D printing, so it will feature too, eventually.