An international research team of biomechanical engineers and surgeons has developed a revolutionary micro 3D printer that can repair damaged tissue during vocal cord surgery. The printer head is only 2.7 millimeters in size, the smallest bioprinter ever developed, and can apply hydrogels to the surgical area with extreme precision.
After vocal cord surgery, many patients develop stiff vocal cords, making it difficult to speak. This is often caused by fibrosis (scarring) in the healing tissue. Hydrogels can counteract this process and support the healing process, but until now, administering these substances by injection has not been sufficiently accurate.
The new robotic printer, developed at McGill University in Canada, offers a solution. "Our device is designed not only for precision and print quality, but also for ease of use during surgery," says Swen Groen, first author and biomedical engineer at McGill. "Thanks to its compact and flexible design, surgeons can seamlessly integrate the system into existing surgical routines and control it manually in a confined working environment."
The technical challenge
Between 3 and 9 percent of people develop a voice disorder in their lifetime as a result of cysts, growths, or cancer on the vocal cords. These are often surgically removed, but many patients suffer from scarring afterwards. This limits the vibrations of the vocal cords and thus the quality of the voice.
To prevent this, the researchers wanted to develop a miniature bioprinter that could operate directly in the throat during surgery, via a laryngoscope through the patient's open mouth. "At first, I thought this was impossible," says Professor Luc Mongeau, senior researcher and biomedical engineer at McGill. "Building a flexible robot smaller than 3 millimeters seemed unfeasible."
The final solution was inspired by an elephant's trunk. The print head consists of a small nozzle at the end of a flexible 'trunk', which is connected via cables to a control module that can be mounted on a surgical microscope. This allows the surgeon to manually control the printer in real time and apply a hyaluronic acid-based gel precisely in lines 1.2 millimeters thick.
Precision and control
To demonstrate its accuracy, the researchers used the system to "draw" shapes such as spirals, hearts, and letters with hydrogel. They then reconstructed simulated vocal cords used for surgical training. The microprinter proved capable of accurately filling tissue defects and even reconstructing an entire vocal cord.
"What makes this technology so special is its predictability," says co-author Audrey Sedal. "The system remains stable, even though it essentially behaves like a flexible water hose. And anyone who has ever seen a garden hose knows how difficult it is to control once liquid is flowing through it."
Towards clinical application
Currently, the printer is still operated manually, but the team is working on a hybrid system that combines both manual and automated control. The next step is to test the technology in animals, with the ultimate goal of starting clinical trials in humans.
"Our goal is to actually bring this technology into the operating room," says Mongeau. "If the results are as good in living tissue as they are in our laboratory tests, surgeons will soon be able to directly reconstruct damaged tissue during vocal cord surgery. That could significantly improve patient recovery and voice quality."
The new microprinter marks an important step toward precision surgery on a micro scale and shows how robotics and bioprinting can come together to enable personalized regenerative therapies, precisely where millimeters make the difference.
3D technology
In 2023, Saxion University of Applied Sciences (Netherlands) investigated whether custom-made3D-printed pessaries could contribute to better care for women with prolapse. A pessary is a plastic ring or cap that is placed in the vagina to support the bladder and uterus and thus reduce symptoms.
Saxion, FabLab Enschede, Gynaecologists Cooperative East Netherlands (Gycon) and ZGT are collaborating on the project. 3D printing technology allows the pessary to be precisely tailored to the patient's anatomy, which increases wearing comfort and promotes self-reliance. This innovation should improve the current, often uncomfortable trial-and-error process of fitting pessaries.
