Today more than two million total joint products including hip and knee replacements are in service in the United States alone and the number is expected to increase in the coming years. To insure high quality and reliability of the devices, tests and inspection of metallic preforms used to make orthopaedic implants are routinely performed by the manufacturers. Eddy current testing among other techniques is used to detect flaws. However, the technique uses conventional inductive sensors, that have reduced sensitivity at the low frequencies needed to penetrate deep into the metal. We propose to develop an improved and automated eddy current system for on line inspection to detect deeply buried flaws using low frequency electromagnetic fields that penetrate deep into the metal. The system will combine extremely sensitive magnetoresistive sensors and advanced noise rejection techniques. Quantum Magnetics is uniquely qualified for this work because of its expertise in NDE applications and ultrasensitive magnetic measurements in noisy environments.
The improved eddy current non-destruction evaluation will greatly reduce the cost and increase the quality and reliability of orthopaedic implants. In addition to this application, the instrument may create a market as a stand-alone diagnostic device. More specifically it may serve as the backbone for an instrument that could be used to monitor devices in vivo for cracks that may result from fatigue loading.
