Handheld multi-parametric photoacoustic microscopy

We report a handheld multi-parametric photoacoustic microscopy system for functional and oxygen-metabolic imaging of the human skin microvasculature. With the high spatiotemporal resolution (3 μm and 10-Hz frame rate), the traverse of single red blood cells through the capillary can be visualized, from which the flow speed can be quantified. Furthermore, the multi-parametric measurement enables comprehensive quantification of the oxygen saturation and release in individual microvessels. The utility of this new technique has been demonstrated by studying the microvascular reactivity in humans.