Multiplexing Optical Fiber Macro-Bend Load Sensors

This paper shows the multiplexing prospects of a load sensing array composed of six in-series optical fiber macro-bends. These fiber loops were individually embedded in silicone elastomer to constitute six sensor elements. Load configurations combining 0.0, 0.5, 1.0, and 1.5 kg were applied on the sensors to study the device performance. The sensor array, composed of standard fibers for optical communications, is spectrally interrogated in the visible window of the electromagnetic spectrum in a multimodal regime of operation. A simple linear regression model was used to estimate an unknown load configuration applied to the array from its associated transmittance spectrum. A sample space of 411 load configurations was used for training and testing the system. The ability of reconstruction was assessed by comparing the actual and predicted configurations of loads. A mean absolute error of 0.12 kg for the estimate was found under the testing conditions. In order to decrease the dimensionality of the dataset, principal component analysis and a discarding variable method were employed. Under 39% of data reduction, no significant impairment on the sensor array performance was observed.