Frequency-resolved photoacoustic viscosity measurement

In this paper, we proposed a photoacoustic (PA) method for detecting liquid viscosity based on frequency-resolved measurement. A negative correlation was investigated theoretically between the liquid viscosity and the full width at half maximum (FWHM) of the PA frequency spectrum. To test the feasibility of this method, water mixed with different concentrations of ink and glycerol was measured. The results indicate that liquids with higher viscosity will lead to a higher FWHM reduction in the PA frequency spectrum and the frequency spectrum was independent from the absorption coefficient of the liquid, which demonstrate that this technique has future potential clinical applications for monitoring the viscosity changes in subcutaneous microvasculature.