Design and Evaluation of a Fiber-Optic Grip Force Sensor with Compliant 3D-Printable Structure for fMRI ApplicationsReport as inadecuate

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Journal of Sensors - Volume 2016 2016, Article ID 6248178, 11 pages -

Research Article

Rehabilitation Engineering Laboratory, ETH Zurich, 8092 Zurich, Switzerland

Spinal Cord Injury Center, Balgrist University Hospital, 8008 Zurich, Switzerland

Neural Control of Movement Lab, ETH Zurich, 8057 Zurich, Switzerland

Received 18 March 2016; Accepted 31 May 2016

Academic Editor: Paola Saccomandi

Copyright © 2016 Tobias L. Bützer 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.


Grip force sensors compatible with magnetic resonance imaging MRI are used in human motor control and decision-making research, providing objective and sensitive behavioral outcome measures. Commercial sensors are expensive, cover limited force ranges, rely on pneumatic force transmission that cannot detect fast force changes, or are electrically active, which increases the risk of electromagnetic interference. We present the design and evaluation of a low-cost, 3D-printed, inherently MRI-compatible grip force sensor based on a commercial intensity-based fiber-optic sensor. A compliant monobloc structure with flexible hinges transduces grip force to a linear displacement captured by the fiber-optic sensor. The structure can easily be adapted for different force ranges by changing the hinge thickness. A prototype designed for forces up to 800 N was manufactured and showed a highly linear behavior nonlinearity of 2.37% and an accuracy of 1.57% in a range between zero and 500 N. It can be printed and assembled within one day and for less than $300. Accurate performance was confirmed, both inside and outside a 3 T MRI scanner within a pilot study. Given its simple design allowing for customization of sensing properties and ergonomics for different applications and requirements, the proposed grip force handle offers researchers a valuable scientific tool.

Author: Tobias L. Bützer, Mike D. Rinderknecht, Gunda H. Johannes, Werner L. Popp, Rea Lehner, Olivier Lambercy, and Roger Gassert



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