Airplane wings that change form in response to air pressure and temperature. Flat-pack furniture that self-assembles when you open the box. Products that decompose into particles or components for easier recycling.
These are some scenarios that could become possible as a result of 4-D printing, technology that could eventually make ordinary 3-D printing seem quaint. 4-D printing is based around the idea of "programmable matter" that changes form or function after it is produced. It's materials that have robot-like capabilities, but without the heavy wiring or electronics.
For a good primer, look no further than a new report from The Atlantic Council, which details some early 4-D printing research and looks at the practical challenges.
Here's how it introduces the topic:
A new disruptive technology is on the horizon that may take 3D printing to an entirely new level of capability with profound implications for society, the economy, and the global operating environment of government, business, and the public.
Imagine a world in which solid material objects can morph into new shapes or change properties at the command of an individual or in pre-programmed response to changing external conditions like temperature, pressure, wind, or rain.
We're a long way from Ikea bookcases that assemble themselves. But groups at Defense Advanced Research Projects Agency, MIT, and Cornell have built prototypes with self-realizing properties. MIT, for example, built the Milli-Motein, a system that could "fold itself into complex shapes." Another MIT project involved a material that could fold itself into a cube. Another embedded wires into a robotic finger that flexed with external stimulus.
The challenges are enormous: from creating material with multi-functional properties, to programming individual "voxels" (volumetric pixels, or fundamental units of matter). And there might also be dangers. If you can program a wing to change shape or a building to disassemble, that power could fall into the wrong hands.
But 4-D printing could also have big advantages, not least for the recovery of precious resources. Here's what the report says about recycling:
Material objects could be recycled not by saving some of the materials such as plastic to be melted down and reused, but by commanding the object to decompose into programmable particles or components that then can be reused to form new objects and perform new functions.