3D-Printed, Tunable, Energy-Harvesting Spinal Cages Can Help Track Fusion Patients' Healing Progress
Clever meta-tribomaterial cages can be tuned to individual patients, require no batteries, and captured data is read using ultrasound.
Engineering researchers at the University of Pittsburgh have designed 3D-printed smart implants designed to monitor the process of spinal fusion, helping to keep an eye on the patient's progress using self-powered sensors.
""Smart implants can provide real-time biofeedback and offer many therapeutic and diagnostic benefits," claims Amir Alavi, assistant professor and lead of the iSMaRT Lab at the Swanson School of Engineering. "But it is very challenging to integrate bulky circuits or power sources into the small area of implants. The solution is to use the implant matrix as an active sensing and energy harvesting medium. That’s what we've been focused on."
The resulting 3D-printed designs, described as a "new class of multifunctional mechanical metamaterials" dubbed meta-tribomaterials, act as all-in-one devices — generating electricity from the application of pressure and then recording data about said pressure onto an on-board chip. Once enough data has been gathered, it can be read non-invasively using an ultrasound scanner.
The implants aren't just there to serve as a sensor, however: They also replace the traditional cages used in spinal fusion surgery, providing a true all-in-one device capable of both assisting with and tracking the progress of the patient's healing.
“Spinal fusion cages are being widely used in spinal fusion surgeries, but they’re usually made of titanium or PEEK polymer materials (a semi-crystalline, high-performance engineering thermoplastic) with certain mechanical properties," Alavi explains. "The stiffness of our metamaterial interbody cages can be readily tuned. The implant can be 3D-printed based on the patient's specific anatomy before surgery, making it a much more natural fit.
"This is a first-of-its-kind implant that leverages advances in nanogenerators and metamaterial to build multi-functionality into the fabric of medical implants. This technological advancement is going to play a major part in the future of implantable devices."
The team has tested the design in cadavers and are preparing for animal model testing, while also investigating its suitability for other medical applications including cardiovascular stents or joint replacement surgeries.
The team's work has been published in the journal Advanced Functional Materials under closed-access terms.