Nitinol – Shape Memory Alloy

written by: Elizabeth Donavan

Remember the Terminator movies with the T-1000? They called it a mnemetic polyalloy. It was supposed to be made up of little nano machines that mimicked living cells, and could copy any shape it was programmed to.

Well, it turns out that is not too far from the truth. There is an alloy called nitinol, which is a combination of nickel and titanium, (with a variant being nickel, titanium, osmium and lanthanum), and it can be “programmed” to return to a specific shape on reaching a certain temperature that is determined through the proportion of nickel to titanium. For example, you can have a stent that reinforces an artery programmed to actuate at the temperature of the blood, and crush the stent so it is easily maneuvered into place, and once it is there, the temperature of the blood causes it to regain its programmed shape.

But it gets better! It turns out that it needs energy to do this, and in order to return to that shape, it draws extra energy from the environment. So it “eats” energy in order to shape shift—just like a living organism eats food to do what it is programmed to do, such as a bacterium or similar life form. So is nitinol, which is also called “bio-metal” really alive? Not really, as one of the requirements is reproduction, which so far it cannot do yet. But it is close. The metal grain structure resembles living cells, even though it cannot come close to living tissue. But it can be considered “nano tech”, as it is programmable from a molecular level. So even though nano-tech remains in the sci-fi realm, this one if very real, and has been with us since at least 1961.

So why are we not using it yet? Well we are, but the alloy is expensive, as it is not mass produced. The argument is that titanium is the culprit, and is horribly expensive. However, this is not the case either, as titanium dioxide is the base of white paint, having replaced the more toxic white lead. If their argument were true, then it would cost $100 per gallon to paint your ceiling. What is more likely is what we are looking at is an artificially inflated price for technology that “they” do not want us to use. Another point is that some researchers are finding out that the “energy eating” aspect of nitinol has a bizarre quality to it that is over unity, and it seems to lower the surrounding temp to do work, instead of the other way around. Some are saying it is negentropic, and has an efficiency way over 100%.

Whatever the case, this material is fascinating to work or play with, and will prove to be a valuable asset in the future, as it can replace hydraulic actuators without having to worry about pumps and leaky plumbing. In fact, it is so powerful it has been estimated to produce up to 20,000 pounds to the square inch of force, way beyond what hydraulic actuators could possibly produce without blowing seals in the process. It is being used in robotics, surgery for implants—as the body does not reject the alloy— and in plumbing for anti-scald shower heads and valves. The actual number of applications are staggering, as it can replace anything that actuator motors or hydraulics can do. The alternative energy applications are possible as well, as motors that can run on waste heat as a co-generation power plant.

I predict we will be seeing much more of this in the future, as the economics cannot be suppressed forever, and once it is “turned loose”, we will see amazing things with this material, such as boats that can be stored in a backpack with ice, and then when thrown into a river, self-actuates into a usable boat, or camping gear that self-actuates such as a tent with a small jolt of current from a solar-charged battery.

The applications are only limited by the imagination.