Fluxgate magnetic sensors are especially important in detecting weak magnetic fields. The mechanism of a fluxgate magnetic sensor is based on Faraday’s law of electromagnetic induction. The structure of a fluxgate magnetic sensor mainly consists of excitation windings, core and sensing windings, similar to the structure of a transformer. To date, they have been applied to many fields such as geophysics and astro-observations, wearable electronic devices and non-destructive testing. In this review, we report the recent progress in both the basic research and applications of fluxgate magnetic sensors, especially in the past two years. Regarding the basic research, we focus on the progress in lowering the noise, better calibration methods and increasing the sensitivity. Concerning applications, we introduce recent work about fluxgate magnetometers on spacecraft, unmanned aerial vehicles, wearable electronic devices and defect detection in coiled tubing. Based on the above work, we hope that we can have a clearer prospect about the future research direction of fluxgate magnetic sensor.

Graphene is attracting much attention in condensed matter physics and material science in the two-dimensional(2D) system due to its special structure, and mechanical and electronic properties. However, the lack of electronic bandgap and uncontrollable phase structure greatly limit its application in semiconductors, such as power conversion devices, optoelectronic devices, transistors, etc. During the past few decades, 2D transition metal dichalcogenides (TMDs) with much more phase structures have attracted intensive research interest in fundamental studies and practical applications for energy storage, as catalysts, and in piezoelectricity, energy harvesting, electronics, optoelectronic, and spintronics. The controllable phase transition also provides another degree of freedom to pave the way for more novel devices. In this review, we introduce the abundant phase structures of 2D-TMDs, including 2H, 1T, 1T’ and charge density waves, and highlight the corresponding attractive properties and applications of each phase. In addition, all the possible methods to trigger the phase transition in TMDs are systematically introduced, including strain engineering, electron doping, alloying, thermal, electric field, and chemical absorption. Finally, the outlook of future opportunities in TMD phase transitions and the corresponding challenges, including both the synthesis and applications, are also addressed.

In this paper, we use 2D PbSe to design a gas sensor to monitor the presence of SO₂ and Cl₂. The first principle calculation shows that our scheme is feasible.