Instrumented knee implant is an innovative and promising concept of monitoring knee biomechanics and it aims to improve the life of a knee implant by providing important *in vivo* biomechanical measurements during intra- and postoperative periods of a total knee replacement (TKR). However, one of the challenges it faces is the need for a sustainable self-powered telemetry system that can function for a wide range of knee implant designs. Herein, we implemented vertical contact mode triboelectric energy harvesters inside a knee implant package to generate the power required for an efficient digitization circuitry. The harvesters produce small-scale electric power from contact and separation methods. Fixing the instrumented package prototype in between a polyethylene bearing and a tibial tray, several experiments were performed under a joint motion simulator. The amplitude and the pattern of the power output varied with the input loadings. Under sinusoidal loads, the largest apparent power scavenged was around 7*µW* at 50 − 2000 *N* and under simulated vertical gaits the harvesters generated around 10*µW* at average human knee loads of 151 − 1950*N* and 17*µW* at 151 − 2437*N* (25% increment of the maximum). Compared to the same amount of vertical gait, the 6 degrees of freedom (DoF) gait had 50 % less production of average electric power. The experiment for each identical harvester at medial and lateral position showed different electrical responses under a similar gait. The results display a great potential for developing a triboelectric based self-powered instrumented knee implant for long-term *in vivo* tibiofemoral force measurement.

 


Characterization of a Packaged Triboelectric Harvester Under Simulated Gait Loading for Load Sensing in Total Knee Replacement

Division / Sponsors: 
Aerospace Division

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2020/volume/84027

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