Improving 3-D Printing by Copying Nature

The public imagination has been captured by 3-D printing in recent months, as people have used it to conjure up custom medical devices, a working handgun, and even an edible pizza. This spring, Staples became the first major retailer to announce that it would carry 3-D printers, putting the technology in the hands of the masses for about $1,300. (See "3-D Printers Are Saving Lives and Serving Pizzas.")

To Janine Benyus, a biologist, author, and innovation consultant, the 3-D printer revolution offers great opportunity, as well as risk. She hopes the technology can be improved by modeling it after natural processes. (See "What, Exactly Is a 3-D Printer?")

"It's going to start slow—people will make toys for their kids and so on," she predicts. But soon, people will be printing out increasingly sophisticated products, from home goods to shoes.

Toxic Concerns

One big problem with 3-D printing in its current form, said Benyus, is that many of the printers rely on toxic building materials, in the form of an increasing array of polymers (plastics), resins, and metal powders.

"Some 'makers' [3-D printer users] are starting to see their skin reacting, and when you look at the material data safety sheets for these materials you see serious warnings," said Benyus. That's a concern, because people are using the printers in their homes and inhaling the fumes, she said.

"We shouldn't have to wash our clothes after we use a 3-D printer, or ask our sons or daughters to take out the hazardous waste trash," she said.

Instead, Benyus argues that all the materials used in 3-D printing should be common and safe for anyone to handle. They should be sourced from local feedstocks, and at the end of their lives, they should be "unzippable" into reusable materials.

Mirroring the Chemistry of Life

Benyus, who wrote Biomimicry: Innovation Inspired by Nature and co-founded the institute Biomimicry 3.8, would like to see a transition in manufacturing—from big, smoke-belching factories to small, clean desktop printers. The key to making it truly sustainable, she said, lies in mimicking how a natural ecosystem functions.

"Nature uses life-friendly chemistry, which is nontoxic and water-based, and which does not require high heat," said Benyus. In contrast, most of the products people use today have been forged in industrial-size furnaces, with a plethora of toxic solvents. A potato chip bag may seem like a simple item, but it is actually made up of several thin layers of different materials, one to make it strong, one to make it airtight, and so on.

But nature creates an enormous amount of diversity from a relatively small palette of materials. Most of the polymers in the natural world fall into about five classes, said Benyus. One is keratin, which makes up skin, hair, and feathers across the animal kingdom. Another is chitin, which makes up exoskeletons in arthropods. The way such basic building blocks are arranged, in terms of internal structure, results in extraordinary differences in animals' size, shape, color, and function—and it can also result in extraordinary strength.

For example, an abalone shell is stronger than high-tech ceramics because of its internal structure, said Benyus. Diatom shells are made of silica (glass), but they are extremely strong because of their stress-distributing pattern of holes.