Lab holographic printer forms hollow 3D shapes in one shot

Researchers at the University of Utah and The University of Texas at Austin have demonstrated holographic 3D printing that can form such complex voids in a single exposure, with the process taking as little as 7.5 seconds.

The problem it addresses is built into conventional layer-by-layer printing: joins between layers can leave leaky seams. The Utah team, led by electrical and computer engineering professor Rajesh Menon and lab member Dajun Lin, instead projects the entire three-dimensional pattern at once. Their method is inspired by photolithography, a technique that uses light and masks to define shapes, but applies it through the depth of the material.

The resin contains string-like polymers that crosslink and harden under laser light. Because the substrate is not perfectly transparent, light would normally scatter as it travels through it and blur the intended shape. A nanopatterned mask compensates for that diffraction, directing energy toward the regions that should become solid. Changes to the resin's chemistry and computational design of the mask keep the areas meant to stay hollow dark enough to avoid hardening.

That solves a limitation in the team's earlier demonstration. Those prints included microtubes as small as 6 micrometers in diameter and structures with dimensional ratios as high as 120:1, but their hollow sections did not extend along the print's height. The new study, published in Science Advances, adds hollow cylinders and cubes with voids along multiple axes.

So what does it change in practice? It points toward complex microstructures that could be produced in seconds rather than the hours other laser-based methods can take, without relying on stacked layers. For now, the cylinder and cube are proof-of-concept prints made by a research team; the work shows a route to larger shapes, not a production deployment.