Most people are familiar with 3D printing by now, through everything from 3D printed toys, to medical prostheses, to food. Now there's a new technology that promises to revolutionize the way we think of additive manufacturing: 4D printing.
3D printers work by building objects layer by layer from the base up, adding on bits of material according to the plan sent to the printer. They allow for the creation of very intricate designs according to exacting specifications, in many cases far outperforming other manufacturing methods. The “3D” in 3D printing refers to the fact that these printers are capable of creating three-dimensional objects, as compared to old ink printers that can only produce printouts in two dimensions.
So, what could a 4D printer possibly do?
One disadvantage to 3D printing is that the materials are usually very static. It can produce things with length, width, and height, but 4D printing allows designers to take a fourth dimension into account: time. The news materials used in 4D printing allow printed objects to change shape over time, when exposed to stressors like heat, pressure, or humidity.
3D printers work by adding on small bits of a single material to build an object. 4D printing uses a variety of materials—some rigid, and some that can change shape when exposed to certain stimuli. This creates a finished object that is capable of changing its shape when exposed to those stimuli, then returning to its original form. The end result is an object that can automatically adapt to changes in its environment in a variety of ways, depending on how these responsive materials are used.
4D printing combines the precision and detail of 3D printing with innovative materials. This means that it can produce parts with incredible time, money, and manpower saving potential.
For example, one possible use for 4D printing is to create responsive water valves that automatically open and close depending on the ambient temperature. This saves the time involved in manually operating the valves, the money it would cost to set up an electronic temperature-monitoring system, and the manpower needed to set up and operate such a system. These valves would also respond to temperature fluctuations without the delay involved in manual or electronic systems, resulting in greater efficiency overall. Valves like this could revolutionize agriculture, fishkeeping, and municipal water filtration alike.
These new responsive materials may also have a dramatic effect on the way parts are shipped and assembled. For example, large, complicated replacement parts could be printed and shipped in a space-saving form, installed, and then activated by providing the right environmental conditions. Creating parts in a condensed format takes up less space when shipping, saving freight costs. Depending on the materials used, all it would take is a change in ambient temperature, or even just immersion in water, to expand them into their final, usable shape.
Responsive materials can also reduce the need for replacement parts. Materials that can adapt to their environment experience less wear-and-tear than materials that remain static, potentially extending their lifespan. Gears made to respond to changes in temperature or pressure are less likely to wear down or deform than older gears, so they'll keep ticking along long after non-adaptive parts have worn out.
4D printing is still in its developmental phase, so there isn't really a firm timeline for deploying the technology. There are a few 3D printable resins that are biocompatible, one of which is capable of deforming under heat and returning to its original shape. These characteristics make it suitable as a scaffold for biomedical applications. The sports industry is also taking note of materials that respond to sudden increases in pressure, for the development of responsive linings for helmets and padding. It's not likely that the average consumer will be able to buy 4D printing supplies for home use, but this technology is already impacting a variety of industries that touch people's daily lives.
3D printing still has its place—not everything needs to adapt to environmental stressors—but 4D printing represents several fascinating new advancements in the sciences and manufacturing. These new, responsive materials will soon find homes in everything from advanced robotics, to medical devices, to housewares.
