System and method for measuring particle size distribution of magnetic nanoparticles under triangular wave excitation magnetic field

Abstract

The invention discloses a system and method for measuring the size distribution of magnetic nanoparticles under a triangular wave excitation magnetic field, belonging to the technical field of nanometer testing. The invention obtains the magnetization curve of the magnetic nano particles on the basis of accurately measuring the excitation magnetic field of the triangular wave and the magnetization intensity signal of the magnetic nano particles. Then the magnetization curve was fitted in the Matlab optimization toolbox, and finally the particle size distribution of the magnetic nanoparticles was obtained. The magnetization curve of the magnetic nanoparticles can be obtained on the experimental device without the need of other external magnetic field measurement equipment, and the measurement cost is low. The particle size distribution can be accurately extracted from the magnetization curve by using optimization algorithms such as global search, without using other characteristics of magnetic nanoparticles, and the measurement process is fast and easy. The measurement method of the present invention is not only applicable to magnetic nanoparticles with a single particle size distribution, but also applicable to magnetic nanoparticles with dimers.

Description

technical field [0001] The invention belongs to the technical field of nanometer testing, and more specifically relates to a system and method for measuring the particle size distribution of magnetic nanoparticles under a triangular wave excitation magnetic field. Background technique [0002] The use of magnetic nanoparticles for concentration temperature imaging and tumor hyperthermia is a new technology. The particle size distribution of magnetic nanoparticles, as an inherent property, affects the application characteristics of magnetic nanoparticles, so it is necessary to study them thoroughly. Commonly used particle size distribution measurement methods include transmission electron microscope (Transmission electronmicroscope, TEM), dynamic light scattering (Dynamic Light Scattering, DLS), etc., all of which are directly measured through their physical properties. TEM and DLS methods have high precision, but the equipment is expensive and the measurement cost is high. ...

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Problems solved by technology

The advantage of the singular value decomposition algorithm is that the particle size distribution can be obtained by solving the matrix equation when the particle size distribution is unknown. The disadvantage is that the condition number of the matrix equation is too large, which is easy to cause false oscillations and other problems.

The fitting of the magnetization curve usually assumes that the particle size of the magnetic nanoparticles obeys a normal distribution or a logarithmic normal distribution, and can be combined with the ZF (zero field) and ZFC (the zero-field cooling) curves of the magnetic nanoparticles to obtain an accurate particle size. diameter distribution, but the acquisition of ZF and ZFC curves requires harsh low temperature conditions

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