Super-Strong Synthetic Muscles Developed

Too Hot! wrote to mention a BBC article about extremely powerful synthetic muscles. From the article: "The most powerful type, 'shorted fuel cell muscles' convert chemical energy into heat, causing a special shape-memory metal alloy to contract. Turning down the heat allows the muscle to relax. Lab tests showed that these devices had a lifting strength more than 100 times that of normal skeletal muscle. Another kind of muscle being developed by the team converted chemical energy into electrical energy which caused a material made from carbon nanotube electrodes to bend."

Re:Geek progress

[dynamo52]

Call me crazy but wouldnt it be easier just to apply electrical energy to begin with?

It is referring to the chemical energy of the fuel cells. All electrical energy derived from batteries is converted chemical energy

Re:End of the blue pill

[pimpimpim]

The corpora cavernosa [medterms.com] is not a muscle!

You don't kiss it...

[dark_requiem]

You BITE his shiny metal ass!

Re:wtf

[Eivind]

I'm hoping you're joking.

First, the human body is indeed effective, but not anywhere *close* to what you claim. The thing is, when you calculate the calorie-need for a certain activity, you typically do so by looking at a table. Say swim a mile in half an hour requires about X calories.

But those numbers are *already* calculated (or more likely measured) including the human inefficiencies.

Ever noticed you get warm and start sweating if you do heavy work ? That's waste heat for you baby.

If you pedal a bike, and generate 100W, you'll use significantly more than 25cal/s doing so (a calorie is about 4 Joule).

Second, producing "450 horsepower pro second" is a completely nonsensical statement. Horsepower (or KW) are measures of *power*, A car migth have 100 horsepower, you can measure it over a second, an hour or a year, it'll still have 100 horsepower.

It's a lot like saying you're 6 feet tall pro second, which makes no sense, unless perhaps you mean you *grow* at 6 feet pro second.

The article is dumb. 100 times as strong as skeletal muscle is a statement with no meaning unless you specify what exactly you mean;

• Is it 100 times as strong as a muscle of the same mass ?
• Is it 100 times as strong as a muschle of the same volume ?
• Do you mean it has 100 times the force ?
• Or 100 times the movement ?
• Or 100 times the power ? (i.e. force times movement)

Re:What about our bones?

[Fred_A]

It definitely can't ; some people can already break their bones with their overdevelopped muscles.

Artificial muscles would definitely require skeletal reinforcement. Although I don't know if anyone has ever worked on this.

I'm not sure if those synthetic muscle can actually be implanted in a living organism either.

Response times seems very slow..

[Anonymous Coward]

Shape memory alloys are already available to hobbiest in the form of nitinol wire. One of the problems is the very slow cycle times. The wire I have seen is only capable of about 3 contract/relax cycles per minute under ambient cooling. The main problem seems to be that once the wire is heated up in order for it to contract, it is hard to dissipate the heat out of the wire fast enough, to get the wire back to its original length or shape. Also, compared to just a normal RC servo, the nitinol wire was very energy inefficient.

Re:wtf

[cbc1920]

I'm assuming that they mean 100 times as much linear force per unit mass. Shape memory alloy (SMA) actuators have been around since the 60's, and they are incredibly powerful. An actuator made from 1mm diameter Nitenol wire can easily lift 10lbs. Their reaction time can be measured in ms if enough heat is applied quickly. So, the claim is not so farfetched.

Of course, there are several caches to using a SMA actuator: First, its operating temperature range is less than 100C, and usually more like 40C, depending on the alloy. Second, the actuator needs to be biased with a spring to return it to its original shape. The spring will have to be pretty hefty- at least 1/3 of the maximum load. If the load is a dead-load, the spring is not needed. Finally, as another poster has mentioned, the initial response can be in the millisecond, but the recovery time can be much longer. This is because of the simple fact that dissipating heat is much more difficult than creating it. If these designers have figured out a way to pump out heat just as fast as they can dump it in, my hat is off to them.

I cannot speak to their efficiency, since it is highly dependent on the design of the device. If *only* enough heat is added to actuate the device, they could be very efficient, but this is rarely the case.