Low-cost/high-reproducibility flexible sensor based on photonics for strain measuring

• Sensitivity: ≈400 pm per 1% elongation.
• Resolution: ≈88 pm per curvature degree.
• Linear behavior with temperature: ≈14 pm °C-1 @ 20-110 °C.
• Flexible sensor: low-cost/high-reproducibility fabrication technology.
• Fabrication: high-simplicity fabrication process.

This paper presents a flexible sensor based on photonics for measuring strain, curvatures and vibrations. This flexible sensor is composed by a Fiber Bragg Grating (FBG) embedded into polydimethylsiloxane (PDMS). The selected FBG resonates at the wavelength of 1552.37 nm and is embedded before the curing for enabling a strong adhesion between both components. Few prototypes were fabricated and characterized. The measurements showed a maximum strain sensitivity of ≈400 pm per 1% elongation, revealing to be sensitive to strain/bending forces and vibration. The measurements allowed to establish a predictable response for both static and dynamic behavior, corresponding to a resolution of ≈88 pm per curvature degree. This flexible sensor also allowed high strain cycles and presented the linear behavior of ≈14 pm °C-1 over the temperature range 20-110 °C. The high-simplicity of the fabrication process results on low-cost with high-degree of reproducibility of their characteristics.