Plastic optical fibre sensor for spine bending monitoring

This paper presents a study on the application of plastic optical fibre for spine bending monitoring based on an intensity modulation. The bending angle is measured as the angle between the emitting and receiving fibres is changed. The measured light attenuation is compared with a theoretical evaluation and the differences between these values are discussed. It was found that the light attenuation for the light intensity agreed well (margin of error < 15%) with the theoretical value for the range between 180 degrees (representing no bend) and 200 degrees and it was significantly increased for the bending angle beyond that value due to the effect of fibre gap increment which resulted in a less reliable experimental estimation.