Ultrahigh sensitive dual-parameter sensor based on wall-core capillary fiber for simultaneous detection of magnetic field and temperature

An ultrahigh sensitive dual-parameter sensor based on a wall-core capillary fiber (WCCF) for simultaneous detection of magnetic field and temperature is proposed. The WCCF is constructed by using a Ge-doped core embedded into the pure silica capillary wall. Based on the WCCF, a dual-parameter sensor for synchronously detecting magnetic field and temperature can be formed by filling the capillary with magnetic fluid (MF) and depositing polydimethylsiloxane (PDMS) on the outer surface of the WCCF. To further improve the sensitivities, two Al wires are placed at the positions closest to the core on both inner and outer walls of the capillary to excite surface plasmon resonance (SPR) effect. Simulation results demonstrate that the sensor can simultaneously detect the magnetic field from 35 Oe to 145 Oe and temperature from 24.3°C to 84.3°C. The maximum magnetic field sensitivity reaches up to 176,000 pm/mT that surpass most of current reports by two orders of magnitude. Meanwhile the maximum temperature sensitivity is 18.4 nm/°C, which is one order of magnitude higher than those of current reports. The WCCF-based dual-parameter sensor has the advantages of high integration, ultrahigh sensitivity and low fabrication difficulty, thus it has the potential of application in fields of biological analysis and environmental magnetic field monitoring.