2D pressure sensing map based on distributed sensing approach for biomedical application

On the basis of Optical Frequency Domain Reflectometry (OFDR) principles, Optical Backscatter Reflectometry (OBR) is able to convert a simple and cheap single mode fiber (SMF) into an effective spatially distributed sensor of temperature and strain. By using different spatial configurations of SMFs, it can be obtained a 2D sensing map of applied forces over a delimited surface. This can be useful in biomedical applications such as force byte measurement. Here, a 2D pressure sensing map, based on distributed fiber optic sensing technique, is presented. The two-dimensional approach is achieved by bending the optical fiber along the surface to get ten lines embedded in silicone material, thus obtaining a carpet of 2 by 6 cm. The highly resolved sensing map is achieved by setting fiber lines 2 mm apart from each other with a sensing range of 2 mm over the fiber. The distributed strain, detected by the embedded fiber, is then converted into a pressure map. The pressure sensitivity coefficient of the map has been successfully characterized. The setup has been validated for surface measurement of wavelength shift values over 9 points on the sensing carpet with 310 total sensing points (10 fiber lines, each having 31 sensing points per 6 cm length). The peculiarity of sensing surfaces based on their mechanical properties gives an opportunity for improved response to curvature due to the embedding or attaching the sensor to irregular shapes and geometries.