Magnetic nanoparticles detection based on nonlinear Faraday rotation

• Published in: Measurement : journal of the International Measurement Confederation Vol. 227; p. 114309
• Main Authors: Cui, Xinchao, Xiang, Feidi, Lu, Chong, Liu, Chunping, Liu, Wenzhong
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.03.2024
• Subjects: Faraday rotation; Harmonic analysis; Magnetic nanoparticles; Magneto-optic effects; Harmonic analysis; Faraday rotation; Magneto-optic effects; Magnetic nanoparticles
• ISSN: 0263-2241; 1873-412X
• DOI: 10.1016/j.measurement.2024.114309

•We propose a model for the nonlinear Faraday rotation of MNPs under the excitation of an external alternating magnetic field.•It has been verified that the higher harmonics of the Faraday rotation can mitigate interference from paramagnetic and diamagnetic backgrounds at lower concentrations.•The higher harmonics of the Faraday rotation of MNPs exhibit a linear relationship with concentration, enabling real-time detection through harmonic analysis.•It is anticipated that MNPs can be utilized as magneto-optical contrast agents to achieve high-resolution in vivo imaging.•Our homemade device can detect rotation angles as low as approximately 2e-7 rad. Magnetic nanoparticles (MNPs) have attracted interest in various research fields due to their special superparamagnetic and strong magneto-optical effects, especially as contrast agents for enhancing medical imaging contrast. Using MNPs capable of generating Faraday rotation angles with higher harmonics as magnetic-optical contrast agents allows for a distinct contrast with biological tissues lacking these higher harmonics. This significantly improves the sensitivity of magnetic-optical imaging. By introducing the interaction coefficient, we propose a model for the nonlinear Faraday rotation of MNPs under the excitation of an external alternating magnetic field. Using our homemade device (which can detect rotation angles as low as approximately 2e-7 rad), we have verified that the higher harmonics of the Faraday rotation can mitigate interference from paramagnetic and diamagnetic backgrounds at lower concentrations. In the future, it is anticipated that MNPs can be utilized as magneto-optical contrast agents to achieve high-resolution in vivo imaging.