Stiff vocal folds are a common complication after vocal cord surgery, affecting how patients speak and recover. Hydrogels can help reduce this risk by supporting tissue healing, but delivering them precisely to the surgical site is extremely challenging. A new solution now addresses this unmet need: a miniature, soft robotic 3D-printing device capable of depositing hydrogels directly onto the vocal folds during surgery.

This technology was developed by a team from McGill University (Montreal, Quebec, Canada) along with collaborating surgeons and published in the journal Device. Their goal was to create a system small and flexible enough to integrate into existing surgical workflows while maintaining printing accuracy in the confined space of the throat. The device is designed to deliver hydrogels with unprecedented precision.

Its printhead measures just 2.7 mm, making it the smallest bioprinter reported to date and small enough to fit through a laryngoscope during vocal cord surgery. Inspired by the movement of an elephant's trunk, the printhead consists of a flexible robotic “trunk” controlled via tendon-like cables connected to a module mounted on a surgical microscope. It delivers hyaluronic-acid-based hydrogel in 1.2 mm lines and maintains smooth, repeatable movements within a 20 mm working range.

To test the device’s capabilities, the team demonstrated manual “drawing” of shapes such as spirals, hearts, and letters on flat surfaces, showing the precision of hydrogel delivery. They then used the system on simulated vocal folds used for surgical training. The bioprinter was able to accurately reconstruct tissue defects—including cavities left after lesion removal and even complete vocal fold reconstruction—highlighting its potential to reduce fibrosis and preserve vocal function.

The team is currently developing semi-autonomous control systems to complement manual operation, with plans to advance toward animal testing and eventually human clinical trials. These steps aim to evaluate the bioprinter’s accuracy, usability, and effectiveness in improving patient outcomes.

“Our device is designed not only for accuracy and printing quality but also for surgeon usability,” said first author and biomedical engineer Swen Groen of McGill University. “Its compact and flexible design integrates with standard surgical workflows and provides real-time manual control in a restricted work environment.”

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