Engineers and orthopedic specialists at the University of Arizona built an ultra-thin wireless sensor that is designed to monitor bone health over long periods of time. The battery-free device is intended to measure a variety of physiological parameters, such as temperature and bone strain, and could be useful for patients with osteoporosis or to monitor healing and guide rehabilitation after a fracture. The device is affixed to the bone surface using a calcium adhesive, which encourages the bone to grow and fuse with the device surface for long-term implantation.
At present, it is difficult to know precisely how a bone is healing. Physiological responses can vary from patient to patient, making personalized treatment difficult. Understanding how a bone is healing and responding to treatment could help guide that treatment so that it is maximally effective and avoids any unwanted side-effects, paving the way for more personalized orthopedic medical care.
“Being able to monitor the health of the musculoskeletal system is super important,” said Philipp Gutruf, a researcher involved in the study, in a University of Arizona announcement. “With this interface, you basically have a computer on the bone. This technology platform allows us to create investigative tools for scientists to discover how the musculoskeletal system works and to use the information gathered to benefit recovery and therapy.”
The device is intended to monitor bone health over long periods, and could be particularly useful for patients who are at increased risk of refractures and bone issues, such as those with osteoporosis. The technology could also help with clinical decisions, such as when to remove plates or screws from a bone.
“As a surgeon, I am most excited about using measurements collected with osseosurface electronics to someday provide my patients with individualized orthopedic care — with the goal of accelerating rehabilitation and maximizing function after traumatic injuries,” said Dr. David Margolis, another researcher involved in the study.
The device was designed to be very thin – about as thick as a sheet of paper – so that it can lie on the bone without irritating overlying muscles and conform to the bone surface. The battery-free technology relies on power-casting and near-field communication to obtain energy and communicate with external devices such as a smartphone.
Finally, a unique adhesive consisting of calcium particles helps the device to adhere to the bone surface for extended periods of time. “The bone basically thinks the device is part of it, and grows to the sensor itself,” said Gutruf. “This allows it to form a permanent bond to the bone and take measurements over long periods of time.”
Study in Nature Communications: Osseosurface electronics—thin, wireless, battery-free and multimodal musculoskeletal biointerfaces