Packaged in-line Mach-Zehnder interferometer for highly sensitive curvature and flexural strain sensing

•An innovative and cost effective packaging of IMZI based curvature and flexural strain sensor which is generally applicable to various IMZI structure designs is demonstrated.•Curvature and flexural strain sensitivity of 85.2 dB m−1 and 0.0148 dB/μɛ, respectively.•The accuracy of the sensor is verified by having good agreement between the measured flexural modulus with the theoretical value of the steel.

The paper presents an innovative packaging approach to allow highly sensitive in-line Mach-Zehnder interferometer (IMZI) sensor to be used for accurate measurement of curvature and flexural strain specifically in civil engineering. The sensor which consists of two tapers is protected within a polypropylene package to survive in harsh, in-the-field conditions. The package design employs cost effective materials without compromising the curvature and flexural strain sensitivity which are 85.2 dB m−1 and 0.0148 dB/μϵ. The accuracy of measurement results is further verified by obtaining the flexural modulus for the steel which is in good agreement with theoretical value.