Micromachined Tactile Sensor Array for RTSA

Abstract

This work presents a polymer-based tactile capacitive sensor capable of measuring joint reaction forces of reverse total shoulder arthroplasty (RTSA). The capacitive sensor contains a polydimethylsiloxane (PDMS) dielectric layer with an array of electrodes. The sensor was designed in such a way that four components of glenohumeral contact forces can be quantified to help ensure proper soft tissue tensioning during the procedure. Fabricated using soft lithography, the sensor has a loading time of approximately 400 ms when a 14.13 kPa load is applied and has a sensitivity of 1.24 × 10−3 pF/kPa at a load of 1649 kPa. A replica RTSA prothesis was 3D printed, and the sensor was mounted inside the humeral cap. Four static right shoulder positions were tested, and the results provided an intuitive graphical description of the pressure distribution across four quadrants of the glenohumeral joint contact surface. It may help clinicians choose a right implant size and offset that best fit a patient’s anatomy and reduce postoperative biomechanical complications such as dislocation and stress fracture of the scapula.

The application of impantable sensors in the musculoskeletal system: a review

“…Their findings indicate the feasibility of measuring joint contact forces intra-operatively in RTSA. Building on this, Leinauer et al (2021) replaced the resistive sensors with capacitive sensors, citing their perceived benefits of enhanced stability and high sensitivity (Capacitive sensor made of PDMS). However, it is important to note that these sensors are intended solely for intra-operative measurements and must be removed before the procedure is completed.…”