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Ultrasound unlocks a safer, greener way to make hydrogels

Researchers at McGill University, in collaboration with Polytechnique Montréal, pioneered a new way to create hydrogels using ultrasound, eliminating the need for toxic chemical initiators. This breakthrough offers a faster, cleaner and more sustainable approach to hydrogel fabrication, and produces hydrogels that are stronger, more flexible and highly resistant to freezing and dehydration.

Hydrogels are gels composed of polymers that can absorb and retain large amounts of water. They are widely used in wound dressings, drug delivery, tissue engineering, soft robotics, soft contact lenses and more.

The new method, now in Advanced Science, also promises to facilitate advances in tissue engineering, bioadhesives and 3D bioprinting.

Gel formation within minutes

Traditional hydrogel manufacturing relies on chemical initiators, some of which can be harmful, particularly in medical applications. Initiators are the chemicals used to trigger chemical chain reactions.

The McGill research team, led by Mechanical Engineering Professor Jianyu Li, has developed an alternative method using ultrasound. When applied to a liquid precursor, sound waves create microscopic bubbles that collapse with immense energy, triggering gel formation within minutes.

"The problem we aimed to solve was the reliance on toxic chemical initiators," said Li. "Our method eliminates these substances, making the process safer for the body and better for the environment."

This ultrasound-driven technique is dubbed "sonogel."

"Typical hydrogel synthesis can take hours or even overnight under UV light," said Li. "With ultrasound, it happens in just five minutes."

Revolutionizing biomedical applications

One of the most exciting possibilities for this technology is in noninvasive medical treatments. Because ultrasound waves can penetrate deep into tissues, this method could enable in-body hydrogel formation without surgery.

"Imagine injecting a liquid precursor and using ultrasound to solidify it precisely where needed," said Li. "This could be a game-changer for treating tissue damage and regenerative medicine. With further refinement, we can unlock new possibilities for safer, greener material production."

The technique also opens the door to ultrasound-based 3D bioprinting. Instead of relying on light or heat, researchers could use sound waves to precisely "print" hydrogel structures.

"By leveraging high-intensity focused ultrasound, we can shape and build hydrogels with remarkable precision," said Jean Provost, one of the co-authors of the study and assistant professor of engineering physics at Polytechnique Montréal.