Magnetless electromagnetic contactless interrogation technique for unwired conductive resonators. Issue 11 (1st May 2019)

• Record Type: Journal Article
• Authors: Baù, M.; Ferrari, M.; Ferrari, V.
• Is Part Of: Electronics letters. Volume 55:Issue 11(2019)
• Page Start: 642
• Page End: 644
• Publication Date: 2019-05-01
• Subjects: coils -- resonators -- vibration measurement -- magnetic sensors -- magnetic field measurement -- pick‐ups -- electric current measurement -- numerical analysis; mathematical model -- mechanical vibration sensing -- excitation field interact -- conductive surface -- eddy currents -- AC magnetic fields -- DC magnetic field -- driving coil -- pickup coils -- external coil arrangement -- magnetic properties -- proximate contactless readout -- passive resonant sensors -- miniaturised electrically conductive resonant structures -- unwired conductive resonators -- magnetless electromagnetic contactless interrogation technique -- aluminium cantilever resonator -- interrogation principle; Electronics -- Periodicals; 621.381
• DOI: 10.1049/el.2019.0067
• Languages: English
• ISSNs: 0013-5194

Abstract

Abstract : An electromagnetic contactless interrogation technique to induce and sense mechanical vibrations on miniaturised electrically conductive resonant structures is presented. The structures can be used as passive resonant sensors with proximate contactless readout. No use is made of poling magnets or wired connections to the resonator that is not required to have magnetic properties. An external coil arrangement has one driving and two pickup coils. The driving coil generates a DC magnetic field and two AC magnetic fields at different frequencies: one for excitation and one for probing. Both the AC magnetic fields induce eddy currents on the conductive surface of the resonating structure. The eddy currents at the frequency of the excitation field interact with the DC magnetic field causing alternating forces, which can set the resonating structure into vibration. The eddy currents at the frequency of the probing field generate a magnetic field that is modulated by the vibrations and detected by the pickup coils. A mathematical model of the interrogation principle has been derived and confirmed by numerical solutions. The experimental demonstration is provided by results obtained on an aluminium cantilever resonator.