Magnetoelastic Bilayer Sensors: From Technology to Application
Eugenijus Kaniušas, Helmut Pfützner, T. Meydan, Vazquez Manuel, Giedrius Varoneckas · Sensor Letters · 2013
Novel technology and new applications of magnetostrictive bilayer sensors were introduced and developed within an international consortium based on the EU project B-SENS. Specific bilayer sensors exhibit bending and temperature sensitivity through specific arrangements. Basically, a magnetoelastic layer (ML) is affixed to a nonmagnetic counter layer (CL) forming a bilayer; bending or heating of the latter induces nearly uniform mechanic stress in ML. The resulting permeability changes within ML are transformed to an output signal reflecting bilayer curvature or temperature. The technological approaches considered not only different materials for ML and CL but also different geometries of the bilayers and various combination methods to form the bilayer. The manufactured sensors ranged from miniature 30 μm thick bilayer wires over micro-bilayers with rectangular structures up to centimetre sized macro-bilayers of 100 μm thickness. A huge number of applications were introduced in both technical and medical fields. Displacement, acceleration, and flow sensors were realised, whereas especially the flat sensor design favoured diverse applications in the medical field. In particular, the sensor principle was very successfully applied for unique skin curvature sensors over numerous human skin regions; it offered for the first time physiological data hidden in the regional and dynamic skin deformations. Among others, blood pressure, eye movements, cardiorespiratory activity could be assessed in an unobtrusive way. After the B-SENS project, several post-projects and studies dealt with further optimisation of the magnetostrictive bilayer sensors and their embedding into plaster-like medical detectors for multiparametric physiological monitoring. Copyright © 2013 American Scientific Publishers All rights reserved.