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Journal of Sensors
Volume 2018, Article ID 7480528, 7 pages
Research Article

Wearable Lumbar-Motion Monitoring Device with Stretchable Strain Sensors

1Graduate School of System Informatics, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501, Japan
2Graduate School of Health Science, Kobe University, 7-10-2 Tomogaoka, Suma, Kobe 654-0142, Japan
3Bando Chemical Industries Ltd, 4-6-6 Minatojima Minamimachi, Chuo, Kobe 650-0047, Japan

Correspondence should be addressed to Hiroyuki Nakamoto;

Received 5 June 2018; Accepted 3 September 2018; Published 8 October 2018

Guest Editor: Aftab M. Hussain

Copyright © 2018 Hiroyuki Nakamoto et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Low-back pain is a common affliction. Epidemiological analyses have reported that periodic cycles of lumbar flexion and rotation are major risk factors for low-back pain. To prevent low-back pain, a lumbar-motion monitoring device could help diagnosticians assess patients’ risk for low-back pain. This study proposes such a device that uses lightweight stretchable strain sensors. Six of these strain sensors form a parallel-sensor mechanism that measures rotation angles of lumbar motion in three axes. The parallel-sensor mechanism calculates rotation angles from the lengths of the strain sensors iteratively. Experimental results reveal that the prototype device is effective for lumbar-motion measurement and significantly improves in terms of wearability over comparable devices.