New Metamaterial Revolutionizes Implantable Medical Devices

Researchers led by Yong Lin Kong of Rice University have created a soft yet powerful metamaterial that can be remotely manipulated to change its size and shape swiftly. The idea, which was reported in Science Advances, marks a substantial development that can potentially alter ingestible and implantable medical devices.

Metamaterials are synthetic structures with unique features not present in natural materials. Instead of only depending on chemical composition, the physical structure, i.e., the precise shape, arrangement, and size of their building components, is central to their successful activity.

Kong and his Rice team developed a novel metamaterial with a unique mix of stability and deformability, which the researchers claim has previously never been accomplished in such delicate materials. This metamaterial is also extraordinarily robust, able to withstand compressive stresses more than ten times its weight and function at temperatures well above physiological limits and hostile chemical exposures.

We programmed multistability, i.e., the ability to exist in multiple stable states, into the soft structure by incorporating geometric features such as trapezoidal supporting segments and reinforced beams. These elements create an energy barrier that locks the structure into its new shape even after the external actuation force is removed.

Yong Lin Kong, Professor, Rice University

The metamaterial’s soft architecture reduces major medical safety problems, such as stomach ulcers, puncture injuries, and inflammation, caused by implantable and ingestible devices with hard components.

Kong and his colleagues employed 3D printing to make molds that form interconnected microarchitectures of tilted beams and supporting segments. This design enables quick switching between open (off) and closed (on) states, and the altered configuration remains even after the magnetic field is withdrawn.

By assembling several of these unit cells as “building blocks,” they create a 3D structure that can change shape and perform complicated peristaltic motions to transport or distribute fluids in a controlled manner when triggered by a magnetic field.

Importantly, the material continued to perform consistently even after prolonged exposure to mechanical stress and acidic corrosion, which simulates the harsh environment of the human stomach.

The metamaterial makes it possible to remotely control the size and shape of devices inside the body. This could enable lifesaving capabilities such as precisely controlling where a device stays, delivering medication where it’s needed, or applying targeted mechanical forces deep inside the body.

Yong Lin Kong, Professor, Rice University

“We are now leveraging this metamaterial to develop ingestible systems that may one day treat obesity in humans or improve the health of marine mammals, and we are collaborating with surgeons at the Texas Medical Center to design wireless fluidic control systems to address unmet clinical needs,” Kong further added.

The study's first author was Taylor Greenwood, Kong's first graduate student, who has since graduated and joined the faculty at Brigham Young University. The study also included Kong’s other graduate students, Brian Elder and Jared Anklam, postdoctoral fellows Jian Teng and Saebom Lee, as well as other colleagues. The Office of Naval Research and the National Institutes of Health provided funding for this study.

Video Credit: Rice Advanced Materials Institute/Youtube.com 

Journal Reference:

Greenwood, T. E. et al. (2025) Soft multistable magnetic-responsive metamaterials. Science Advances. doi.org/10.1126/sciadv.adu3749