Tiny optical sensor aims to illuminate spinal biomechanics

August 14, 2008 -- Researchers at two Canadian universities -- the University of Victoria and the University of British Columbia -- say they have developed a miniature fiber Bragg grating (FBG) sensor. This, "the only optical, the smallest and the most mechanically compliant disc pressure sensor," has proven its ability to measure pressure within the spine.

Aug 15th, 2008

August 14, 2008 -- Researchers at two Canadian universities -- the University of Victoria and the University of British Columbia -- say they have developed a miniature fiber Bragg grating (FBG) sensor. This, "the only optical, the smallest and the most mechanically compliant disc pressure sensor," has proven its ability to measure pressure within the spine.

The intervertebral disc (IVD) pressure sensor boasts pressure sensitivity seven times greater than that of a bare fiber, and a major diameter and sensing area of only 400 µm and 0.03 mm2, respectively. The researchers say their design is an improvement over other FBG pressure sensors that achieve increased sensitivity through mechanical amplification schemes -- which typically result in major diameters and sensing lengths of many millimeters, they say. This size advantage makes it possible for the researchers' sensor to be used between discs in the spinal column -- even discs of minimal height (that is, cervical and degenerated discs). Thus, the sensor is expected to enable measurements that could lead to new understanding of biomechanics. Such research could potentially lead to discoveries regarding back pain.

The team has validated its sensor by conducting IVD pressure measurements in the spines of pigs, and comparing the FBG measurements to those obtained using the current standard sensor for IVD pressure. The sensor's sensitivity, as predicted using numerical models, matched with that measured experimentally. IVD pressure measurements showed excellent repeatability, too, the researchers say, and agreement with those obtained from the standard sensor.

The team's research is described in the August issue of the Institute of Physics' Measurement Science and Technology journal.

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