A Capacitance Sensor for Monitoring Brace Compliance and Pressure in Adolescent Idiopathic Scoliosis

Orthopaedic braces are commonly used in the treatment of adolescent idiopathic scoliosis. Compliance to prescribed wear time and maintaining optimum pressures are crucial for positive treatment results but few current designs provide real-time monitoring. In this study we present the design, fabrication and characterisation of capacitance sensors and evaluate their suitability within a brace. We demonstrate a quick and low effort method of fabricating foam-based porous dielectrics that facilitate the manufacture of shielded soft force sensors in less than 2 hours, with minimal tooling or training required. Sensors with two types of foams are characterised for their electrical response to compressive loads, with peak changes in capacitance of 1 pF, and an operating range of over 40 N suitable in an orthopaedic brace. The integration of sensors fabricated flat, into the curve portion of a brace is shown with the performance remaining stable despite the curvature.