SHAHRZAD (SHERRY) TOWFIGHIAN, PHD
SELF-POWERED LOAD SENSORS FOR TOTAL KNEE REPLACEMENT
Abstract: Total knee replacement (TKR) is a common surgical treatment for end-stage knee osteoarthritis, performed over 600K times per year in the USA alone and much of the surgeries is occurring in younger patients. Loosening and instability issues have been reported that requires revision surgeries. These problems can be avoided by routine monitoring of the load across the knee. However, there is no simple, low cost embedded sensors for use in the TKR implant. Load sensing TKR implants can address this need by monitoring prosthesis health and providing quantitative data to support patient claims of pain or instability. However, powering such devices throughout the entire life of the knee replacement is a challenge, and self-powered telemetry via energy harvesting is an attractive solution. In a project funded by the National Institute of Health (NIH), we implemented vertical contact mode triboelectric energy harvesters inside a knee implant package to generate the power required for embedded digitization and communications circuitry. The harvesters produce small-scale electric power from physiologically relevant loads transmitted through the knee during activities of daily living. Experiments were performed on a joint motion simulator with an instrumented package prototype between the polyethylene bearing and tibial tray. The amplitude and the pattern of the power output varied with the input loadings. Our team has also developed a frontend electronic system that rectifies/regulates the harvester output and digitize the signal. The PCB prototype consumed approximately 5.35 W, and the harvester produced 10-20 W on average loads. Our results demonstrate the triboelectric energy harvesting is a promising technique for self-monitoring the load inside the knee implant.
Biography: Dr. Shahrzad (Sherry) Towfighian received the B.S. degree from the Amirkabir University of Technology, Iran, the M.S. degree from Ryerson University, Canada, and the Ph.D. degree from the University of Waterloo, Canada, in 2011. All of her degrees were in Mechanical Engineering. She completed her one year of postdoc at Ryerson University before joining the Mechanical Engineering Department at Binghamton University in Fall 2013. Her research interests are microelectromechanical systems and vibration energy harvesting for bio-medical devices. She focuses on creating theoretical and experimental frameworks to explain the underlying mechanism of electro-mechanical systems. Using these frameworks, she seeks innovative methods to improve functionality of devices for various applications. Her research activities includes micro-accelerometers, microphones and micro-shock sensors with high sensitivity and resolution. She was a recipient of several grants from the National Science Foundation and the National Health Institute and has published more than 75 journal and conference papers.
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