M-mode photoacoustic particle flow imaging.

Recently, there has been growing interest in the development of photoacoustic flow measuring methods aimed to study microvascular blood flow in biological tissue. Here, we describe the M-mode photoacoustic particle flow imaging, using an optical resolution photoacoustic microscope equipped with a high-repetition-rate pulsed dye laser. We studied the flow of a diluted dyed particle suspension in a small tube embedded in a nonscattering medium as well as in a scattering medium simulating biological tissue. Potentially, the method can be applied to detect the flow speed of single red blood cells in a capillary.