Detecting trace ferromagnetic wear particles in lubricating oil is important for assessing the degree and mode of wear in mechanical equipment. Based on Faraday's law of electromagnetic induction, this study presents an experimental apparatus for measuring ferromagnetic particle content using a self-developed sensor, an LM324 amplifier, a TLC549 A/D converter, an STC89C52 single-chip microcontroller, and a CH451 display driver chip. A non-intrusive measurement scheme for ferromagnetic particle detection is proposed. The quantitative relationship between variations in the detection signal and the amount of iron wear particles is established, enabling sensor signals to be converted into electrical outputs. Through static and dynamic experiments, the optimal operating parameters and detection accuracy of the system are determined. The results demonstrate that the apparatus can achieve non-contact quantitative detection of ferromagnetic particles. In addition to its engineering value, the device can also be used in college physics laboratory teaching as a verification experiment based on electromagnetic induction. Owing to its simple structure, it helps students develop hands-on skills and improve their ability to apply physical principles to practical problems.

The growing complexity of artificial intelligence-driven devices requires multifunctional materials that exhibit nonlinear responses to address key challenges in adaptive signal processing and energy-efficient computing. To meet these demands, hexagonal Bi₂Se₃ ceramics are synthesized with controlled thicknesses via a chemical reduction synthesis method. The aggregated Bi₂Se₃ nanosheets exhibit remarkable capacitance tunability under an applied bias voltage. Moreover, a significant increase in the electromagnetic interference (EMI) shielding performance was achieved at a bias voltage, which was attributed primarily to improved electrical conductivity. At a bias voltage of 15 V and an optical power density of 200 mW/cm², the average total EMI shielding effectiveness (SE_T) of Bi₂Se₃ nanosheets increases to 62.8 from 23.9 dB. The collaborative combination of multiple superior functionalities within a single material platform with tunable capacitance, dynamically tunable EMI shielding, and excellent light response endows Bi₂Se₃ nanosheets with great potential for applications in intelligent storage, microelectronics, and low-light photodetectors.