Design of an MR-compatible three-axis force sensor

This paper presents a newly designed and developed MR-compatible three-axis force sensor: its principle, structure and performance. It employs a new MR-compatible optical micrometry based on differential measure of light intensity. This technology enables highly accurate and sensitive two degrees-of-freedom displacement sensing by using optoelectronic devices and pair of fiber optics. In order to realize three-axis force sensitivity, two micrometers are aligned in orthogonal directions. The accuracy of this force sensor is better than 3.0% and the maximum displacement of the detector is about 40 μm under the applied force ranging from 0 to 15 N in vertical, and -8 to 8 N in horizontal directions. The loss of homogeneity of the magnetic field and signal-to-noise ratio of the MR image caused by this sensor are observed to be 0.49 ppm and 0.49 to 7.30% that show the sufficient MR compatibility of this sensor.