Browsing by Subject "piezoelectric sensing"

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    Embedded piezoelectrics for sensing and energy harvesting in total knee replacement units
    (SPIE, 2015-04) Wilson, Brooke E.; Meneghini, R. Michael; Anton, Steven R.; Department of Orthopaedic Surgery, IU School of Medicine
    The knee replacement is the second most common orthopedic surgical intervention in the United States, but currently only 1 in 5 knee replacement patients are satisfied with their level of pain reduction one year after surgery. It is imperative to make the process of knee replacement surgery more objective by developing a data driven approach to ligamentous balance, which increases implant life. In this work, piezoelectric materials are considered for both sensing and energy harvesting applications in total knee replacement implants. This work aims to embed piezoelectric material in the polyethylene bearing of a knee replacement unit to act as self-powered sensors that will aid in the alignment and balance of the knee replacement by providing intraoperative feedback to the surgeon. Postoperatively, the piezoelectric sensors can monitor the structural health of the implant in order to perceive potential problems before they become bothersome to the patient. Specifically, this work will present on the use of finite element modeling coupled with uniaxial compression testing to prove that piezoelectric stacks can be utilized to harvest sufficient energy to power sensors needed for this application. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
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    Energy Harvesting and Sensing With Embedded Piezoelectric Ceramics in Knee Implants
    (IEEE, 2018-01) Safaei, Mohsen; Meneghini, R. Michael; Anton, Steven R.; Orthopaedic Surgery, School of Medicine
    The knee replacement is one of the most common orthopedic surgical interventions in the United States; however, recent studies have shown up to 20% of patients are dissatisfied with the outcome. One of the key issues to improving these operations is a better understanding of the ligamentous balance during and after surgery. The goal of this paper is to investigate the feasibility of embedding piezoelectric transducers in the polyethylene bearing of a total knee replacement to act as self-powered sensors to aid in the alignment and balance of the knee replacement by providing intra- and postoperative feedback to the surgeon. A model consisting of a polyethylene disc with a single embedded piezoelectric ceramic transducer is investigated as a basis for future work. A modeling framework is developed including a biomechanical model of the knee joint, a finite element model of the knee bearing with encapsulated transducer, and an electromechanical model of the piezoelectric transducer. Model predictions show that a peak voltage of 2.3 V with a load resistance of 1.01 MΩ can be obtained from a single embedded piezoelectric stack, and an average power of 12 μW can be obtained from a knee bearing with four embedded piezoelectric transducers. Uniaxial compression testing is also performed on a fabricated sample for model validation. The results found in this paper show promising potential of embedded piezoelectric transducers to be utilized for autonomous self-powered in vivo knee implant force sensors.