Researchers at MIT's Media Lab have developed a method for 3D printing hair structures with a diameter as small as 50 micrometers each. With the ability to create finely detailed surfaces, touch sensors and even actuating motors, the technology could be used to make customized paint brushes, Velcro-like mechanical adhesives, and touch-sensitive plush toys.

The goal of the project, known as Cilllia, was to develop a technique for creating hair structures that were simple and customizable, and suggest some ways such a technology could be used to design everyday interactive objects.

To begin, a specially developed program generates bitmaps of the desired hair structures, and allows users to adjust hair density, structure, angle and thickness, without the tedious job of building models of each individual strand. The bitmap can then be 3D printed, creating a dense surface of hair.

The researchers suggest the technique could find numerous applications, from 3D-printed objects with extremely detailed surface textures, to paint brushes that could be customized by adjusting the arrangement of the hair, and the shape of the tips, into different patterns. The fibers can also be made to interlock like Velcro to make a relatively strong mechanical adhesive.

But where it gets particularly interesting is when vibration is thrown into the mix. Objects placed on top of the hairs will move in the direction the fibers are pointing, and designing particular patterns in the surface can send them along a set path. The researchers demonstrated actuating motors made with the hair as well, which they used to make a windmill device that spins when vibrations are detected to provide a visual notification for when your phone is on silent.

When attached to a microphone, the hairs can become like a touchscreen, able to detect the direction and speed of a swipe. As an example, the researchers created a toy rabbit with the 3D-printed hair on its back, to teach kids the correct way to pet an animal. When a user swipes downwards, moving with the hair, an LED inside the toy lights up green. If you swipe upwards, going against the hair, the light would turn red.

The video below shows how the hair is created and some of its applications, while the paper detailing the technology can be found here (PDF).

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