Torque measurements are used in a number of controls applications, but indirect coupling, size, and the quality of commercially available sensor materials can limit their utility. Here, a compact magnetostrictive torque sensor is made by electrodeposition of Fe1-xGax (0.1<x<0.4, aka Galfenol), onto Cu shafts using rotating cylinder electrodes (RCEs). The alloy composition is controlled by tuning the RCE rotation rate between 500 and 2000 RPM, while the electrode potential is varied from 1.15 to 1.20 V. Direct coupling of Fe1-xGax to the shaft with the electrodeposition process enables magnetic anisotropy to be induced via shaft surface texturing, as seen by a 260% increase in susceptibility along a 400 grit texturing direction versus perpendicular to the texture and compared with the isotropic behavior of films deposited on polished shafts. Inverse magnetostriction-based torque sensing is demonstrated by measuring stray fields from Fe1-xGax films as torque loads of 0-16.9 Nm were applied to the shaft. Films electrodeposited on circumferentially textured shafts had torque responses almost 1.5 times greater than films electrodeposited on longitudinally textured shafts and five times greater than films on polished shafts.
Bibliographical noteFunding Information:
VI. ACKNOWLEDGEMENTS Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. Additionally the UMN NFC with the support of the NNIN for their facilities and technical assistance.
Manuscript received January 1, 2019; revised March 9, 2019; accepted March 11, 2019. Date of publication March 19, 2019; date of current version July 17, 2019. This work was supported by NSF under Grant ECCS-1231993. The associate editor coordinating the review of this paper and approving it for publication was Prof. Marco Petrovich. (Corresponding author: Matt Hein.) M. Hein is with the Electrical and Computer Engineering Department, University of Minnesota Twin Cities, Minneapolis, MN 55455 USA (e-mail: firstname.lastname@example.org).
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- force sensors
- instrumentation and measurement
- magnetic devices
- magnetic sensors
- magnetomechanical effects
- magnetostrictive devices
- thin film sensors
- torque measurement