Healing hydrogels—cross-linked polymer chains that hold a lot of water—can promote tissue healing and prevent postsurgical complications. But the current method of delivery, using a needle from the outside, lacks precision. That means for surgery of the larynx, for example, the material often doesn’t reach important areas in the vocal cords.
Researchers led by Luc Mongeau, a professor of mechanical engineering at McGill University, have now created a new way to deliver hydrogels during surgery by printing the material directly into the throat (Device 2025, DOI:10.1016/j.device.2025.100973).
Bioprinting hydrogels inside the body has been tested before, but with printers too large for vocal cord surgery, says Swen Groen a PhD student in Mongeau’s research group. To reliably reach the vocal cords, the bioprinter needs to be small enough to allow surgeons to see where they are working but still accurate enough to deposit hydrogels in the correct location, he says.
To make a device with these qualities, the team built a silicone-based prototype to test how well the cables and motors work together. The group then miniaturized the system, ending up with a nozzle with a 2.7 mm diameter, about 76% smaller than the previous smallest bioprinter.
The gel tested with this device was recently developed in Mongeau’s research group specifically for this type of surgery, Groen says. The material, which has not been described in the literature yet, helps restore tissue. The gel becomes less viscous when under pressure, making it ideal for the small nozzle of the bioprinter.
To test the machine, the researchers used a surgical model that replicated vocal cords; Groen was able to successfully reconstruct parts of the vocal fold, which cannot be treated well with current methods. “I’m not a surgeon at all, and I have no training in it, and I was able to get pretty good results,” he says.
While the team found that small variations in precision don’t significantly affect the final printed results, it will be important to have the system tested by surgeons to determine the real accuracy, Groen says.
Mariah Hahn, a professor of biomedical engineering at Rensselaer Polytechnic Institute who was not involved in the study, agrees that a surgeon needs to test the device to determine its value, but says the engineering has potential to make this kind of surgery better.
Beyond delivering hydrogels to the vocal cords, the team could take the machine a lot of different routes, including testing it for other procedures in the heart or liver, Groen says.
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