Contactless and absolute linear displacement detection based upon 3D printed magnets combined with passive radio-frequency identification

摘要

Within this work a passive and wireless magnetic sensor, to monitor lineardisplacements is proposed. We exploit recent advances in 3D printing andfabricate a polymer bonded magnet with a spatially linear magnetic fieldcomponent corresponding to the length of the magnet. Regulating the magneticcompound fraction during printing allows specific shaping of the magnetic fielddistribution. A giant magnetoresistance magnetic field sensor is combined witha radio-frequency identification tag in order to passively monitor the exertedmagnetic field of the printed magnet. Due to the tailored magnetic field, adisplacement of the magnet with respect to the sensor can be detected withinthe sub-mm regime. The sensor design provides good flexibility by controllingthe 3D printing process according to application needs. Absolute displacementdetection using low cost components and providing passive operation, long termstability and longevity renders the proposed sensor system ideal for structuralhealth monitoring applications.