Fiber-optic sensors are a powerful tool to investigate physical properties like temperature, strain, and pressure. Such properties make these sensors interesting for many applications including biomedical applications. Fiber sensors are also a great platform for distributed sensing by using the principles of optical frequency domain reflectometry. Distributed sensing is becoming more and more used to achieve high-resolution measurements and to map physical properties of biomaterials at small scale, thus obtaining 2D and 3D mapping of a particular area of interest. This work aims at building and investigating a 2D sensing carpet based on a distributed fiber sensing technique, to map local pressure applied to the carpet. The two-dimensional mapping is obtained by embedding a single-mode optical fiber inside a soft silicone carpet. The fiber has been bent and arranged in a specific configuration characterized by several parallel lines. Different fiber fixation methods have been investigated by means of a comparative analysis to perform better characterization and to achieve a more precise response of the carpet. The best pressure sensitivity coefficient (0.373 pm/kPa or considering our setup 1.165 nm/kg) was detected when the fiber was fully embedded inside the silicone carpet. This paper demonstrates the possibility of mapping a 2D distributed pressure over a surface with a resolution of 2 mm by 2 mm. The surface of investigation is 2 cm by 6 cm, containing 310 sensing points. The sensing carpet has been validated selecting several preferential positions, by testing the consistency of the results over different portions of the carpet.

Optical Backscatter Reflectometry (OBR) is capable of converting a simple and inexpensive single mode fiber (SMF) into an effective spatially distributed sensor of temperature and strain based on the concepts of Optical Frequency Domain Reflectometry (OFDR). A 2D sensing map of applied forces over a defined surface may be created by employing different spatial configurations of SMFs. This can be beneficial in biological applications such as measuring bite force. In this paper a 2D pressure sensing map based on distributed fiber optic sensing is provided. The two dimensional technique is performed by bending the optical fiber along the surface to acquire ten lines embedded in silicone material, thereby generating a carpet of 2 by 6 cm. The highly resolved sensing map is created by spacing fiber lines 2 mm apart with a sensing range of 2 mm across the fiber. The embedded fiber detects distributed strain, which is subsequently transformed into a pressure map. The dependence of strain on the toughness of silicone material was observed. The map's pressure sensitivity coefficient has been effectively identified. The setup has been validated for surface measurement of wavelength shift values over 9 sensor carpet locations with a total of 310 sensing points. Since the sensor is embedded or attached to irregular forms and geometries, the distinctiveness of sensing surfaces allows for enhanced responsiveness to curvature due to its mechanical characteristics.

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.