Just when I thought I couldn’t get any more excited about the way technology is moving I discovered 4D printing. With 3D printing taking off in a huge way, influencing all aspects of life and science from healthcare to homes, it seemed that printing technology had reached its peak. How wrong I was – 4D printing is simply magical.

Forget everything you know about flat-packed furniture because 4D printed objects build themselves. Yes, you read that correctly they BUILD THEMSELVES!

4D printing is making the most of so called smart materials – usually metals or plastics that can change shape in response to changes in their environment.

This means that they can be formed and set into a particular shape then squashed, flattened, scrunched up or remoulded into any other shape but they will always return to their original shape under certain conditions.

These conditions include change of temperature, moisture, electricity or acidity.

Memory metals (also called smart memory alloys or SMAs) are smart materials that will revert back to their original shape when heated or stressed. They are usually a metal alloy including titanium such as nitinol, which is a mixture of titanium and nickel. Nitinol was first discovered in 1959 by a Naval researcher looking to improve missiles but it was tricky to make. It wasn’t until the 1990s that it became possible to produce it reliably and in big enough quantities to really start thinking about using it in everyday applications.

The reason that nitinol is able to undergo its seemingly magical transformation in shape is due to its structure. The way atoms line up in a substance is called its crystal structure.

Nitinol is able to take on two crystal structures – one at low temperatures and one at high temperatures. From about 20°C to roughly 50°C nitinol’s crystal structure will transform from its low temperature shape called austenite to its high temperature structure called martensite. Unsurprisingly, this range is called the transformation temperature.

This ability to transform in response to heat means you can make all kinds of useful things out of nitinol and be confident that they will heal themselves if deformed.

For example if you have eyeglasses made of nitinol you can step on them, sit on them, find them in the washing machine and all you need to do is dip them in hot water over 50°C and the metal will return to the correct shape (the glass may very well not!). These cool metals are used in many applications including in aeroplanes, dental braces, medical devices and buildings.

Now take this amazing material, apply 3D printing technology and you have the ability to cheaply and easily print a flat, plastic-coated metal, that, when heated to 50°C, folds into the desired object. You can imagine that companies like Ikea will be jumping out of their skins to start making use of 4D printing.

And your kitchen table and chairs are only the beginning, maybe one day the entire skeleton of a skyscraper could be made this way. Transformers eat your heart out!

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