Prototype smart, bionic knee implant can power itself.

Knee replacement surgery, where a damaged, worn or diseased knee is replaced with an artificial joint, is the most common joint replacement procedure, with the American Academy of Orthopedic Surgeons predicting by 2030 total knee replacement surgeries will grow by 673%.  As these knee replacements can wear out within five to ten years innovation in this area is sorely needed.  Now, a study from researchers at Binghamton University is working on a prototype bionic knee implant with built-in sensors designed to use the knees’ own abilities to generate energy to power it.  The team states the implants will be able to provide doctors with regular activity updates and are powered by the patient’s movement.  The study is published in the journal Smart Materials and Structures.

Previous studies show increasingly, knee replacement surgery is being performed on younger, more active patients. As these patients tend to be more active their knee implants can also wear down more quickly with doctors unable to discern whether an implant is too worn until the patient begins to develop symptoms.  Unfortunately by this point, the damage to the implant has already been done, therefore, finding the perfect balance between activity levels and the integrity of the implant has proven to be quite difficult.  The current study presents a prototype for a smart bionic knee implant powered by a triboelectric energy harvester with front end electronics to provide load and wear data in realtime.

The current study develops a prototype of a smart knee implant with an energy harvester, tested under a mechanical machine to examine its output under equivalent body loads.  The prototype uses triboelectric energy, a type of energy collected from friction, so when the patient walks, the friction of the implant’s micro-surfaces coming into contact with each other can be used to power the implant and its smart sensors.  The team states the smart implant will need 4.6 microwatts of energy to power itself based on the calculation involving the average amount of energy generated through the motion of walking.

Results show the output of the harvester is used to charge a supercapacitor, which in turn is used for low resolution sensing of the load through a peak detector and analog-to-digital converter. Data findings show sensing the load several times a day is feasible by relying only on harvested power. The lab states their work demonstrates triboelectric energy harvesting is a promising technique for self-powering load sensors inside bionic knee implants.

The team surmises they have provided a prototype smart, self-powered knee implant with the potential to reduce the number of knee replacement surgeries.  For the future, the researchers state their smart implants could give feedback to doctors and help researchers in the development of future novel implants.

Source: Binghamton University

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