Imagine being able to inject implants into the body in a liquid state and then solidifying them once in place, making surgeries minimally invasive. This could one day be possible thanks to a new 3D printing technique based on ultrasound.
Common 3D printing often involves constructing three-dimensional objects by placing successive layers of a viscous material that later hardens. Another widespread method of 3D printing, named volumetric printing, uses beams or light patterns which pass through the transparent top and sides of a container filled with a photosensitive gel-like resin.
The resin solidifies, or polymerizes, wherever it’s exposed to the light; the rest of the resin remains a gel. By adjusting the light source’s position, reaching different areas of the resin, it’s feasible to slowly construct a highly detailed three-dimensional object.
However, volumetric printing has its limitations. For the light to get to its target, both the container and resin need to be transparent. Given that human skin and biological tissue are nearly opaque, allowing only a tiny amount of light to penetrate a few millimeters, this method cannot currently be utilized to fabricate implants inside the body.
Scientists from Duke University and Harvard Medical School created a novel technique known as deep-penetrating acoustic volumetric printing, or DVAP, recognizing the constraints. This method doesn’t rely on photosensitive resin, but on a heat-sensitive “sono-ink” which firms up when it comes into contact with ultrasound pulses.
The sono-ink, being highly viscous, can potentially be inserted into the body region where an implant is needed. It then solidifies when introduced to ultrasound waves coming from a targeted external probe. Any residual ink can be removed from the body using a syringe after forming the desired structure.
The sono-ink can be custom-made to mimic different biomaterials such as bone, and can be made durable or biodegradable, depending on the required usage.
In the conducted lab trials, the scientists have employed the DVAP process to seal a segment of a goat’s heart (a necessary procedure for treating nonvalvular atrial fibrillation), mend a bone imperfection in a chicken’s leg, and introduce chemotherapy-drug-releasing hydrogels inside liver tissue.
“Because we can print through tissue, it allows for a lot of potential applications in surgery and therapy that traditionally involve very invasive and disruptive methods,” said Duke’s Assoc. Prof. Junjie Yao, who led the study along with Harvard’s Assoc. Prof. Y. Shrike Zhang and postdoctoral research fellow Xiao Kuang. “This work opens up an exciting new avenue in the 3D printing world, and we’re excited to explore the potential of this tool together.”
A paper on the study was recently published in the journal Science.
Sources: Duke University, American Association for the Advancement of Science via EurekAlert
“Why did the 3D printer go to therapy? Because it had too many layers of unresolved issues!”
0 Comments