Development of Viscosity Measurement System Utilizing the Frequency Characteristics of Magnetic Nanoparticles

Viscosity measurement is a crucial parameter for understanding the properties of substances and has applications in medical fields such as coagulation measurement. In this study, we aimed to measure viscosity by utilizing the dependence of the frequency characteristics of the AC magnetic susceptibility of magnetic nanoparticles on viscosity. First, we developed a system to measure the AC magnetic susceptibility of magnetic nanoparticles using the gain-phase method. Then, assuming a log-normal distribution of the particle size of the magnetic nanoparticles, we analyzed the viscosity from the imaginary part of the frequency characteristics of the AC magnetic susceptibility obtained by the developed system. The correlation between the analyzed viscosity and the viscosity obtained from a viscometer and a densitometer was y = 0.607x + 0.471 (R<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> = 0.993), indicating a strong linear correlation. This result suggested that the developed system can measure the solvent viscosity through calibration.