Layered polymer whole structure health monitoring using capacitance sensing

Capacitive sensors have a wide field of applications for measuring a parameter that results in displacement of parallel capacitor plates, displacement of the sandwiched dielectric material, or a change in the dielectric´s material properties. This theory of parallel plate capacitance can be used in a layered polymer structure to allow continuous whole structure health monitoring. The sensor itself is created from integrated layers of conductive polymers separated by a polymer layer which has a high dielectric constant. This paper is an overview of current research into the application of this type of sensor. When incorporated into a hydraulic hose, it was found that capacitance measurement of the sensor increased slightly noticeably at the start of failure in a linear manner as pressure inside the hose increased. Similar results are seen when investigating on-highway tires and lumbar total disc replacement.