Development of a 3D Printed Gap Gauge with Embedded Force Sensor for Balancing Unicompartmental Knee Arthroplasty

A novel gap-gauge with embedded sensing is developed for assisting in Oxford Unicompartmental Knee Arthroplasty (OUKA). A fully 3D printed differential capacitive sensor for normal forces is embedded into the Fused Deposition Modelling (FDM) fabricated body of the gap-gauge. The sensor consists of three conductive parallel-plates realizing two capacitive sensors with a common ground plate. It is demonstrated that for the set of specifications the 3D printed device is potentially suitable for the application. Minimal drift, weak non-linearity and hysteresis in the response are present. There is good agreement between the designed and true sensitivity.