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

TL;DR

This paper presents a passive, wireless magnetic displacement sensor using 3D printed magnets with tailored magnetic fields combined with RFID technology, enabling sub-millimeter absolute displacement detection for structural health monitoring.

Contribution

It introduces a novel 3D printed magnet with a linear magnetic field profile integrated with RFID and GMR sensors for passive displacement measurement.

Findings

Detects displacements within the sub-mm range

Uses low-cost, passive components for long-term stability

Offers flexible sensor design via 3D printing

Abstract

Within this work a passive and wireless magnetic sensor, to monitor linear displacements is proposed. We exploit recent advances in 3D printing and fabricate a polymer bonded magnet with a spatially linear magnetic field component corresponding to the length of the magnet. Regulating the magnetic compound fraction during printing allows specific shaping of the magnetic field distribution. A giant magnetoresistance magnetic field sensor is combined with a radio-frequency identification tag in order to passively monitor the exerted magnetic field of the printed magnet. Due to the tailored magnetic field, a displacement of the magnet with respect to the sensor can be detected within the sub-mm regime. The sensor design provides good flexibility by controlling the 3D printing process according to application needs. Absolute displacement detection using low cost components and providing passive operation, long term stability and longevity renders the proposed sensor system ideal for structural health monitoring applications.