While traditional 3D printers work by depositing layers of material, light-based 3D printing can solidify entire shapes at once. In tomographic volumetric additive manufacturing (TVAM), for example, laser light selectively hardens a photosensitive resin into a 3D form within seconds. However, TVAM is highly inefficient: less than 5% of the projected light power actually contributes to the printing process.
In a study published in Light: Science & Applications , EPFL researchers introduced a new approach to TVAM that is 70 times more efficient than previous techniques. They encode a desired object as a hologram by modulating the alignment (phase) of light waves rather than their brightness (amplitude), as previous methods have done, preserving far more of the laser’s power. The team used a high-speed phase-only modulator to project holograms at 1440 frames per second directly into a vial of rotating resin, solidifying entire millimeter-scale objects within seconds, and centimeter-scale objects within minutes.
Importantly, this efficiency now makes it possible to bioprint structures at near-clinical scale. Using only a 150-mW laser diode, the researchers printed a life-sized ear in a hydrogel: a landmark step toward bioprinted implants for reconstructive medicine. Cell-laden hydrogels were printed. Confocal imaging six days later confirmed that cells remained viable and formed organized networks, showing that the process does not harm living cells.
To boost surface quality, the researchers combined their efficient light engine with a new strategy for reducing random light interference called speckle, which can lead to grainy surfaces. Beyond improved efficiency, their method’s phase control also enables holographic printing with self-healing beams, which produce higher-fidelity 3D printed objects in media interspersed with light-scattering particles.
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. “Our approach brings volumetric printing closer to real-scale and biologically compatible manufacturing using simple, low-power laser sources, making the dream of patient-specific bioprinted implants for ears, cartilage, and other tissues much closer to reality.”
Light: Science & Applications
High-efficiency multi-scale holographic volumetric 3D printing with a phase light modulator