The new technique, tested in a life-size, 3D-printed model, features thin, spaghetti-like strips fitted with magnets that can be moved into place near uric acid kidney stones with a robotic arm operated by doctors.

The soft, flexible robot strips are about a centimeter long and contain an enzyme called urease. Once in place, the urease reduces the acidity of the surrounding urine, thereby dissolving stones until they are small enough to pass naturally in just a few days.

“There is currently no good treatment method available for this type of kidney stone,” said Dr. Veronika Magdanz, a professor of systems design engineering at Waterloo who consulted urologists in Spain and Canada during the research project.