A recent study published in Nature Communications introduces advancements in Holographic Direct Sound Printing (HDSP), a technique that utilizes high-pressure sound waves to structure polymer materials, such as resin, into precise 3D forms. The research was led by Mahdi Derayatifar from Concordia University, Montreal, and Mohsen Habibi from the University of California, Davis, with additional contributions from Professors Rama Bhat and Muthukumaran Packirisamy, also of Concordia University.
The authors argue that HDSP could enable the creation of geometries and internal features that are challenging or impossible to achieve with conventional methods. The study outlines advancements in the process and identifies areas for future research to fully assess its potential and limitations.
How Holographic Direct Sound Printing Works
In an article published by UC Davis, Habibi explained that HDSP uses an acoustic hologram to project and print an object in its entirety in one step. Unlike typical holograms, which are created with light, this method employs sound waves to generate high-pressure zones in a controlled environment.
During the process, a robotic arm positions the printing platform above a submerged transducer that emits high-pressure sound waves. The space between the transducer and the platform is filled with a polymer material. The robotic arm precisely navigates the platform along a defined path to shape the object, simultaneously lifting the structure upward from the build chamber. This coordinated movement results in the formation of a 3D structure.
Building on his previous work with direct sound printing (DSP), Habibi emphasized that HDSP improves upon DSP by enabling the continuous projection and printing of a two-dimensional image in one step. This advancement increases efficiency, allowing for faster production compared to the traditional layered methods used in both DSP and conventional 3D printing.
Future Applications of HDSP
So far, the researchers have printed simple geometric shapes like a maple leaf, a helix, and a “U” shape using HDSP. The technique holds promise for creating biological tissues such as bone and cartilage for medical applications, as these tissues have relatively simple geometries that align with HDSP’s capabilities.
While additional research is needed before this technology can be used for tissue repair in humans, Habibi explained that advances like HDSP bring society closer to realizing such applications. “When direct sound printing was first introduced, people thought it was science fiction. Now, it’s science moving forward,” said Habibi.
Advances in Sound-Based 3D Printing
Recent advancements in sound-based printing technologies, including Dynamic Interface Printing (DIP) from the University of Melbourne and acoustophoretic 3D printing from Harvard, are demonstrating potential in enhancing bioprinting. Researchers at the Collins BioMicrosystems Laboratory, led by biomedical engineer David Collins, introduced DIP, a 3D bioprinting technique that utilizes acoustic waves to guide cells into precise configurations, enabling the rapid production of complex human tissues. Unlike traditional methods, which build tissue layer by layer, DIP overcomes speed and structural limitations, accelerating tissue engineering.
Elsewhere, researchers from Harvard University’s John A. Paulson School of Engineering and Applied Sciences developed an acoustophoretic 3D printing technique in 2018 that uses sound waves to form droplets of various viscous fluids into intricate, additively manufactured structures. Published in Science Advances, this novel patterning method is poised to drive scientific progress in optics, electronics, biology, and other fields, offering transformative potential for a wide range of industries.
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Featured image shows Mohsen Habibi Habibi and Anis Askari with the machine for printing 3D images using sound waves. Photo: University of California, Davis.
