3D printing tissue-like structures with light

In 2025, EPFL scientists published an improved approach to tomographic volumetric additive manufacturing (TVAM): a 3D printing method that uses laser light to harden a rotating vial of photosensitive resin into a desired shape. In that work, the researchers used holograms to encode 3D forms by modulating the alignment (phase) of light waves rather than their brightness (amplitude), as previous methods had done, preserving far more of the laser’s power.

Now, the team from the Laboratory of Applied Photonic Devices (LAPD) in the School of Engineering has implemented a new platform for the holographic approach to improve TVAM, making it 70 times more efficient than previous techniques. This leap is thanks to the team’s use of a new device that directly controls the phase of a light beam in a volumetric 3D printing system for the first time.

In their experiments, the researchers used their new system to solidify entire millimeter-scale objects within seconds, and centimeter-scale objects within minutes. Importantly, the method’s phase control enables holographic printing with self-healing beams, which produce higher-fidelity 3D-printed objects in light-scattering media, such as those containing living cells.

“Our method’s demonstrated efficiency and precision finally makes it possible to bioprint tissue-like structures at near-clinical scale,” says LAPD head Christophe Moser. “We have printed structures substantially larger than those achieved with previous holographic approaches, despite increased light scattering caused by the embedded cells.”

The innovation has been published in Light: Science & Applications.

A step toward bioprinted implants

In their study, using a 150-mW laser diode, the researchers printed a life-sized human ear, a step toward bioprinted implants for reconstructive medicine. Using a smaller print construct (volume 64 mm³), the researchers confirmed that after six days, the embedded living cells were still viable, and had even formed organized networks.

To further boost the surface quality of objects printed with their technique, the researchers combined their efficient light engine with a new strategy for reducing random light interference called speckle, which can lead to grainy surfaces.

“Our approach brings volumetric printing closer to real-scale implants, and biologically compatible manufacturing using low-power laser sources,” summarizes lead author and LAPD PhD student Maria Alvarez-Castaño.

The researchers say that future work will focus on enhancing projection fidelity, as well as studying the limits of beam shaping for printing in bioresins with high cell densities. Other enhancements for TVAM platforms, to be described in forthcoming publications, include better ways to print directly onto or around existing objects, and new methods for shaping microscopic details more accurately by predicting how chemicals inside a resin react during printing. The latter method notably leverages holographic volumetric additive manufacturing to fabricate objects simply by projecting a hologram onto a vial of resin, without needing to rotate it.