Capacitive sensing of interfacial stresses

Studying interfacial stresses is an important step towards understanding load distributions in mechanical, biomedical, and industrial systems. This paper presents a capacitive sensor that is capable of simultaneously measuring compressive and shear stresses. The sensor consists of two electrode layers separated by a set of flexible and compressible polymer pillars. The sensor´s response to compressive and shear stresses was tested and characterized up to 320 kPa and 70 kPa respectively. An algorithm to estimate the applied stresses based on sensor output was developed and validated. The applied compressive stresses were estimated with an accuracy of 95.04% and shear stress with an accuracy of 89.45%.