en.Wedoany.com Reported - A research team from the Swiss Federal Institute of Technology Lausanne (EPFL) has introduced a volumetric 3D printing platform that reportedly improves energy efficiency by 70 times compared to previous technologies. The system uses holographically shaped lasers to fabricate tissue-like structures at near-clinical scales. This achievement is based on tomographic volumetric additive manufacturing, a process that solidifies a photosensitive resin in a rotating vial using laser light to form the target geometry. Earlier holographic methods optimized traditional techniques by modulating the phase of light waves, rather than their amplitude or brightness, to encode 3D shapes, thereby preserving more of the laser's available power.
The team's Laboratory of Applied Photonics Devices further introduced equipment capable of directly controlling the phase of the light beam within the volumetric printing system. The researchers noted that such a capability had not been previously demonstrated in this context. Using a 150-milliwatt laser diode, the platform solidifies millimeter-scale objects in seconds and centimeter-scale objects in minutes.
Light scattering in biological media typically poses a problem for bioprinting, leading to degraded print quality. The platform addresses this issue through self-healing beams, a property of phase-controlled holographic projection that maintains resolution even in light-scattering environments such as cell-laden resins. Christophe Moser, head of the Laboratory of Applied Photonics Devices, stated: "The efficiency and precision demonstrated by our method finally make it possible to bioprint tissue-like structures at near-clinical scales." He added: "The structures we printed are much larger than what was previously achievable with holographic methods, even though the embedding of cells increases light scattering."
In experimental tests, the team printed a life-sized human ear using a gelatin-based resin. In another construct with a volume of 64 cubic millimeters, embedded living cells remained viable after six days and formed organized networks. The researchers also combined the light engine with a speckle reduction strategy to counteract random light interference that can produce a grainy surface finish. The study's first author, doctoral student Maria Alvarez-Castaño, said: "Our method brings volumetric printing closer to real-scale implants and biocompatible manufacturing using low-power laser sources." The research was published in the journal *Light: Science & Applications*.
The research team stated that future work will focus on improving projection fidelity and investigating the limits of beam shaping in high-cell-density bioresins. Subsequent efforts may also involve printing directly onto or around existing objects, as well as achieving more precise microscale geometry formation through predictive modeling of resin chemistry. The researchers also reported progress on a static holographic printing method, which projects images onto a stationary vial without rotation, potentially further simplifying the tomographic volumetric additive manufacturing process.
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