Technology of thermally driven and magnetomotively detected MEMS microbridges

• Published in: Sensors and actuators. A. Physical. 2016-04, Vol.240, p.17-22
• Main Authors: Moczała, M., Babij, M., Majstrzyk, W., Sierakowski, A., Dobrowolski, R., Janus, P., Grabiec, P., Gotszalk, T.
• Format: Article
• Language: English
• Subjects: Actuation; Devices; Electric bridges; Electric wire; Interferometers; Magnetic resonance; Magnetomotive detection; Microbridge; Signal processing; Thermal actuation; Vibration
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2016.01.041

•The device is actuated electrothermally using Joule heating in a device-integrated metallization line.•The resonance is detected with an electromotive force (EMF) in magnetic field.•Combination of thermal drive on half of resonance frequency and magnetomotive read-out at resonance frequency gives possible to achieve signal separation in the frequency domain.•Frequencies of actuation signal and of the signal corresponding with the bridge displacement are separated therefore both electrical processes can be done in parallel. Here we present a microbridge system with integrated metal wires enabling magnetomotive and electrothermal control of driving. We present the microbridges’ architecture and manufacturing process. The device was actuated electrothermally in vacuum and in ambient conditions at room temperature using Joule heating in a device-integrated metallization line. The resonance was observed by measurement of electromotive force (EMF), which was induced along the wire during vibration in magnetic field. We show how microbridge can be operated in resonance mode with combined electrothermal actuation and magnetomotive read-out methods. This can be done when the thermal drive is done at half of the resonance frequency and magnetomotive read-out is performed at the resonance frequency. Such a technology ensures the separation of the drive and electrothermal signals in the frequency domain. Because the frequency of actuation signal and the frequency of the signal corresponding with the bridge displacement are separated both electrical processes can be done in parallel. The frequencies of the observed resonant peaks are in very good agreement with the results obtained using precise interferometers.