Spider Silk-Based Fiber Magnetic Field Sensor

We propose and demonstrate a spider silk-based fiber sensor for magnetic field measurement. The spider silk plays two roles: one is the carrier of sensitive magnetic materials (Streptavidin-Biotin modified magnetic nanoparticle), the other is to act as a light guide material to participate in mode interference. We pull a single-mode fiber to the biconical structure and wrap the spider silk around the tapered-shaped region. Since the refractive index of spider silk is higher than that of the fiber core, the high-order mode beam transmitted in the fiber cone will couple into spider silk, and we may obtain the multimode interference spectrum. Furthermore, the Streptavidin-Biotin modified magnetic nanoparticle is sensitive to the magnetic field and will change the effective refractive index of spider silk. Therefore, we may perform the magnetic field sensing by wrapping the spider silk around the tapered-shaped single-mode fiber and combining the Streptavidin-Biotin with the spider silk. The experimental results show that the maximum sensitivity can reach 1126.3 pm/Oe, which is higher than most all-fiber magnetic field sensors. The average sensitivity is 400pm/Oe in the range of 0-120 Oe. The response time is 146.9 ms. The proposed magnetic field sensor has the advantages of easy manufacturing, environmental friendliness, and simple structure. Therefore, the magnetic field sensor has potential applications in various fields, such as military, environmental, and industrial.