Design and Development of a High-Sensitivity, Portable, and Low-Cost Fluxgate Magnetometer

Abstract

Fluxgate magnetometers are widely used, as they exhibit high sensitivity, while operating at room temperature. However, their cost, as well as the need for additional external units (e.g., power supply, data acquisition units, and so on), may act as negative factors. In this article, a new fluxgate magnetometer is presented based on a pulsed excitation signal, offering low power consumption and high sensitivity, while being low-cost and small. It can operate in open-loop or closed-loop mode, depending on the application and the strength of the externally imposed magnetic fields. The sensor’s racetrack topology, consisting of two excitation coils and one sensing coil, eliminates the effect of the sensor’s excitation field, in order to detect only the externally imposed magnetic field. Moreover, an additional coil is used to compensate the external magnetic field during the closed-loop operating mode. The device is completed with the required electronics and a microcontroller to generate the sensor’s excitation signal, receive its output, and compensate the magnetic background through proportional–integral–derivative (PID) control. Measurements can be transmitted in a wired or wireless manner to the desired device (e.g., personal computer, smartphone, and so on). The printed circuit board (PCB) of the sensor was designed and manufactured, including the electronics, as well as a rechargeable lithium battery to demonstrate the portability of the sensor. The final device was mounted in a 3-D printed enclosure, enabling its use under a variety of conditions. Initial measurements show that the sensor can act as a magnetic anomaly detector, exhibiting high sensitivity. As a result, it can be used for geomagnetic, biomedical, non-destructive testing, and other applications.