Highly Sensitive Temperature and Curvature Sensor Based on Seven-Core Fiber

•A high-sensitivity temperature and curvature micro-fiber Mach-Zehnder interferometer (MMZI) sensor is proposed and demonstrated. The composite structure with the tapered seven-core fiber (SCF) and the SCF-SMF peanut structure is fabricated. The new structure sensor can significantly improve the coupling efficiency and stimulate high-order modes in the sensor for high sensitivity.•The maximum temperature sensitivity is 836.67 pm/ °C in the range of 35 °C to 40 °C, which is the highest temperature sensitivity of the peanut-shaped MMZI sensor to the best of our knowledge. Furthermore, the sensor can be used for curvature measurement. When the curvature change from 0 nm/m−1 to 0.0522449 nm/m−1, the sensitivity can achieve 93.33664 nm/m−1.•This composite structure of the proposed sensor provides a novel method to fabricate a high-sensitivity sensor by combining different types of optical fibers.