Distinguishment between contributions of deformation and eddy current effects to compressive impedance responses of intrinsic flexible coil

Abstract

The impedance of the intrinsic flexible coil (composed of the conductive fillers and the polymer matrix) is sensitive to the deformation of the coil in the compression phase and the distance between the coil and the metallic target in the approaching phase, which indicates that the intrinsic flexible coil has the potential to be used as the deformation/distance sensor. The impedance response of the coil to the compression (i.e. compressive impedance responses) is induced by not only the deformation effect but also the eddy current effect, which complicates the analyses on the sensing properties of the coil. To distinguish the compressive impedance responses induced by the aforementioned two effects, the experiments under the conditions of the nonmetallic and metallic targets are designed. Under the condition of the nonmetallic target, the deformation raises the impedance amplitude and reduces the impedance angle in the compression phase, and there is no change in the impedance in the approaching phase. Under the condition of the metallic target, the impedance amplitude is raised and the impedance angle is reduced with the decrease/increase of the distance/deformation in the approaching/compression phase. The change in the normalized impedance during the compression under the condition of the metallic target is far more than that under the condition of the nonmetallic target, indicating that the contribution of the eddy current effect to the compressive impedance response is dominant over the deformation effect.