Grüneisen parameter-based photoacoustic system for quantitative blood flow velocity measurement

Blood flow dynamics are a vital functional parameter within biological tissues. Accurate measurement of blood flow plays a crucial role in the early diagnosis and treatment of numerous diseases, including burns, strokes, atherosclerosis, diabetes, and cancer. In addition, blood flow conditions significantly affect the distribution and efficacy of drugs within the human body, making precise quantification of blood flow highly valuable in clinical medicine. In this study, we propose a method for measuring blood flow velocity based on photoacoustic thermal sensing. This approach overcomes several limitations of traditional photoacoustic velocity measurement techniques, which often rely heavily on medium heterogeneity and are limited in measurement range. By introducing a “thermal tagging” mechanism, we establish a correlation model between flow velocity, temperature, and photoacoustic pressure. This enables high-precision velocity quantification using only a single pulsed laser source, and it is applicable to both homogeneous and heterogeneous media. Based on this principle, we developed a photoacoustic velocity measurement and imaging system. Experiments were carried out to conduct single-point flow velocity detection and two-dimensional mapping of both morphology and velocity. By adjusting the system parameters, the flow velocity measurement range can be adjusted individually, and the average flow velocity measurement error over the range is kept to within 3%. This work provides a novel, non-invasive, rapid, and high-resolution approach for quantitative blood flow measurement. The method expands the functional boundaries of photoacoustic technology and lays a foundation for its broader application in multimodal biomedical diagnostics.