SMA-Coated Bimorph Integrated Approach Toward Temperature Sensing Using Optical Fiber

Abstract

A novel bimorph-integrated-optical fiber structure has been proposed for sensing the temperature with linearity within a broad range. Shape memory alloy-coated Kapton-polyimide sheet was used as a bimorph. Its displacement with temperature rise proportionally impacts the optical signal and inculcates a linear sensing behavior in the optical fiber. Significant optical intensity changes have been recorded with good linearity within 40 °C–120 °C. Sensitivity of ∼14.8 mV/ °C in martensite while ∼21.2 mV/ °C in the austenite phase transition range was observed with an accuracy error of ±0.014 °C. Linear intensity changes were also confirmed from the spectral analysis within two regions, however, there was a sharp deflection in wavelength of ∼1.6 nm. The technology offers an economical sensing solution with the potential for integration with the Internet of Things. It has capability for smart sensing, thereby serving contemporary industrial requirements.