A new type of 3D printing could dramatically speed up the way tiny, complex objects are made.
Instead of slowly building an object one layer at a time, researchers have developed a technique that can create an entire 3D structure—including hollow spaces inside it—with a single burst of laser light.
Scientists at the University of Utah worked with researchers at The University of Texas at Austin to develop the technology.
Their latest results, published in Science Advances, show that the method can produce complicated hollow structures in as little as 7.5 seconds. By comparison, some existing laser-based 3D printing techniques can take hours.
Traditional 3D printers usually construct objects layer by layer. While effective, this approach can be slow, and the boundaries between layers may create weak points or tiny leaks.
Printing an entire object at once could help avoid these problems.
The new technique takes inspiration from photolithography, a technology widely used to manufacture computer chips. Photolithography normally uses a mask to control which parts of a light-sensitive material are exposed to light. The researchers adapted this basic idea so that it works throughout a three-dimensional volume.
Their printing material is a specially designed liquid resin containing long polymer molecules. When certain areas of the resin are exposed to laser light, the molecules link together and harden. Material that does not receive enough light remains uncured and can later be washed away.
Controlling the laser inside the resin, however, is difficult. The material is not perfectly transparent, so light can bend and scatter as it travels through it. This can blur the intended pattern and reduce printing accuracy.
To solve the problem, the researchers developed a tiny nanopatterned mask that manipulates the laser light. The mask creates a carefully designed holographic light pattern that compensates for the way the resin affects the laser. As a result, light is concentrated in the exact regions that need to become solid.
The team had previously used the method to print arrays of extremely small tubes, some measuring only about 6 micrometers across. However, those structures were limited in the directions in which hollow spaces could be created.
The latest version goes much further. By changing the chemistry of the resin and carefully controlling how light travels through it, the researchers can create bright regions that harden while keeping other regions dark enough to remain liquid.
This allowed them to print genuinely three-dimensional objects containing enclosed hollow spaces along multiple directions, including hollow cylinders and cubes.
The demonstration is still an early proof of concept, but the researchers believe the approach could eventually be expanded to larger and increasingly complicated structures.
By creating an entire object in seconds rather than slowly assembling it layer by layer, holographic laser printing could open the door to faster manufacturing of intricate 3D structures that are difficult to produce with today’s printing technologies.
Source: KSR.
