Magnetostrictive type inductive sensing pressure sensor

• Published in: Sensors and actuators. A. Physical. Vol. 238; pp. 25 - 36
• Main Authors: Chang, Heng-Chung, Liao, Sheng-Chieh, Hsieh, Hsieh-Shen, Wen, Jung-Hung, Lai, Chih-Huang, Fang, Weileun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2016
• Subjects: CoFeB; Coiling; Detection; Diaphragms; Gauge factor; Inductive sensing; Inductors; Inverse-magnetostriction effect; Magnetic films; Magnetic permeability; Magnetostriction; Pressure sensor; Pressure sensors; Inverse-magnetostriction effect; CoFeB; Pressure sensor; Inductive sensing; Gauge factor
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2015.11.023

•This study proposes a design concept of the pressure sensor based on the inverse-magnetostriction effect and inductive sensing technique.•The gauge factor could be modified from 55 to 852 by the design parameters of the planar sensing inductor.•The gauge factor of 852 is about 12 times the factor of the general piezoresistive type pressure sensor.•The presented magnetostrictive type pressure sensor is a strain induced sensing device. The same sensing mechanism can be further expanded to other applications.•The existing of the magnetic coils offers the potential to integrate with inductance reading circuitry for the wireless transmission applications. This study presents a magnetostrictive type inductive sensing pressure sensor which consisted of a planar coil, CoFeB magnetic films, and a Si diaphragm. As the Si diaphragm deformed by a pressure load, the inverse-magnetostriction effect would cause permeability changes of the CoFeB magnetic films. Thus, the permeability changes as well as the pressure load can be detected by the inductance change of a planar inductor. To demonstrate the feasibility of the proposed pressure sensor, the planar inductor designs of different coil turns and in-plane patterns of magnetic films are fabricated and tested. Preliminary measurements show that the pressure sensors with 6 and 12 coil turns have sensitivities of 0.079 %/kPa and 0.064 %/kPa, respectively. In addition, based on the in-plane pattern design of the magnetic films, the gauge factor could be tuned from 55 to 852.