Advances in bioelectronics have provided important insights into parts of the body that had been largely unexplored. However, the musculoskeletal system has remained an understudied area, in part because of the difficulty of stabilizing sensors on bone and obtaining long-term, reliable signals through a large, soft-tissue envelope.

In 2021, the Biomaterial Lab introduced the first-ever permanent, implantable bone sensors: "osseosurface electronics," created in collaboration with UArizona engineers and other scientists.

These tiny, wireless and battery-free devices include sensors for multiple measures of bone health data as well as LEDs with therapeutic and research applications. The devices permanently bond to bone using a novel calcium ceramic coating.

This new class of medical technologies features soft mechanics and an ultra-thin form factor: roughly the thickness of a single sheet of paper, allowing the devices to closely conform to the curvature of bones.

Osseosurface electronics feature miniaturized, multimodal biointerfaces comprised of sensors and optoelectronics directly adhered to the surface of the bone, which provide real-time recordings of bone strain and millikelvin-resolution thermal maps of bone surface, a valuable indicator of stiffness and inflammation throughout bone healing.

Additionally, integrated LEDs can deliver optical stimulation, for therapeutic applications. Optical stimulation also has applications in research beyond orthopedic medicine, such as in the growing field of optogenetics, which combines photostimulation and genetically modified neurons for use in brain mapping and studying neural communications.

Power is sent to the device using near-field communication, eliminating the prohibitive bulk of an on-board battery. The same technology transmits data from the device to external devices, including something as accessible and ubiquitous as an everyday smartphone.

Journal Citation

Cai, L., D. A. Gonzales, A. Azimi, R. Peralta, M. Johnson, J.A. Bakall Loewgren, B. E. Villalobos, E.C. Ross, J.A. Szivek, D.S. Margolis, et al., "Osseosurface electronics – Thin, wireless, battery-free and multimodal musculoskeletal biointerfaces", Nature Communications, vol. 12-1, 2021.