Clinically versatile handheld photoacoustic microscopic probe from head to toe

We developed a fast-scanning handheld photoacoustic microscopy (PAM) system equipped with a waterproof two-axis MEMS scanner for high-resolution, label-free imaging of human skin. The system achieves 19.9 µm lateral and 57.0 µm axial resolution and captures a 4 × 4 mm² field of view in 1.6 seconds. In vivo imaging visualized palm vasculature, melanocytic nevi, and tongue papillae. Additionally, dynamic monitoring during cuff-induced occlusion and reperfusion demonstrated real-time vascular response tracking. This compact and portable PAM system offers promising clinical utility in dermatology and beyond, enabling point-of-care imaging and functional monitoring without the need for external contrast agents.