A team from the Swiss Federal Institute of Technology in Lausanne (EPFL) has just published its third improvement to a volumetric 3D printing technique that began in 2017. The latest version is 70 times more efficient than previous ones and, for the first time, allows for the printing of structures containing living cells.
The result of the new study is a life-size human ear printed in gelatin-based hydrogel. The ear contains embedded human cells that, six days after printing, were still alive and had begun to organize into networks. To understand why this matters, we need to go back nearly a decade.
Ear printed using the TVAM process (Photo Credit: LAPD / EPFL).
What is TVAM?
The technique in question is called tomographic volumetric additive manufacturing (TVAM). Instead of building objects layer by layer like a conventional 3D printer, TVAM involves projecting a laser beam from different angles onto a rotating tank filled with photosensitive resin. Where the accumulated energy exceeds a certain threshold, the resin solidifies. The entire object is formed in a single step, in just a few seconds.
The technique has been under development at EPFL since 2017, when an initial team laid the groundwork for the method. A few years later, Professor Christophe Moser’s group at the LAPD took over. Since then, they have published three improvements addressing the limitations that made the method impractical for biomedical applications.
- 2022: Opaque resin. The classic TVAM process only worked with transparent resins, which allowed light to pass through without being deflected. The resins used in biomedicine are opaque, and light scatters within them before reaching its intended destination. The solution was to use a camera to track the actual path of the light and apply computational corrections in real time, achieving nearly the same precision as with transparent resin.2025: Energy consumption. Although by that point the process was already fast and accurate, only 1% of the projected light actually reached the resin. So they needed a lot of light to get good results. As a solution, the researchers chose to project a hologram directly onto the rotating resin tank. This allowed them to use 25 times less optical power to print the same objects at a higher resolution.
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2026: Scale and living cells. The holographic enhancement of 2025 still relied on hardware that modulated the amplitude of the light, not its phase directly. In the new study, the team implemented for the first time a device that directly controls the phase of the light beam, which increased efficiency by a factor of 70. Using a 150 mW diode laser—much more modest than those used previously—they printed one-centimeter objects in minutes and one-millimeter objects in seconds, and confirmed cellular viability after printing. Maria Alvarez-Castaño, a LAPD doctoral student and lead author of the study, states: “Our approach brings volumetric printing closer to real-scale implants, and biologically compatible manufacturing using low-power laser sources.”
Objects 3D-printed using the 2022 TVAM process. On the left, transparent resin; on the right, opaque resin before and after correction (Photo Credit: EPFL/Alain Herzog).
Why the Energy Source Makes All the Difference
It may seem like a technical detail, but the energy source isn’t. Living cells are sensitive to light, so overexposing them during the printing process would irreversibly damage them. By reducing the required energy by a factor of 70, the team made the process compatible with real living cells.
“Our method’s demonstrated efficiency and precision finally makes it possible to bioprint tissue-like structures at near-clinical scale,” LAPD head Christophe Moser said. “We have printed structures substantially larger than those achieved with previous holographic approaches, despite increased light scattering caused by the embedded cells.”
Ph.D. student María Álvarez-Castaño and LAPD Director Christophe Moser (credit: Adrien Buttier/EPFL).
What’s Still Missing?
The 3D-printed ear is just the first step. The team will continue working on improving printing accuracy, using bio-resins with higher cell density, and refining methods for printing onto existing objects. They also announce a future variant that would eliminate the need to rotate the container to simplify the system. Although the ear is not yet ready for implantation in a person, this multi-year research shows us that bioprinting is on the right track. Don’t you think? You can learn more about EPFL’s latest breakthrough here.
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*Cover photo: holographic projection of a model of a human ear onto a sample container (Photo Credit: Adrien Buttier/EPFL).