Dual-pulse Photoacoustic Flowmetry with Single Laser Source

Blood flow measurement is crucial in biological application. Here, we report a fast dual-pulse photoacoustic flowmetry based on a multi-wavelength optical-resolution photoacoustic microscopy (OR-PAM) system with single laser source. The mathematical model illustrates the relationship between the 545/532 PA ratio and the blood flow speeds, and the calibration for oxygen saturation (sO₂) systematic error caused by Grüeneisen relaxation (GR) effect. The validation phantom experiments are conducted by blood-filled transparent tube and show a flow range of 0–23 mm/s. The in vitro and in vivo experiments are both carried out by dual-pulse and PAD flowmetry. Finally, total hemoglobin concentration, blood %low and compensated oxygen saturation can be measured simultaneously in large field of view by OP-PAM, indicating its potential in functional imaging application.