Head-mounted photoacoustic microscopy for multiparametric cerebrovascular imaging in freely behaving mice

Anesthetized and head-restrained settings for intravital microscopy of the mouse brain affect neurovascular activities and restrict natural behaviors. To overcome these limitations, we have developed a lightweight (1.1 g) head-mounted photoacoustic microscopy device for label-free imaging of the cerebral microvasculature in freely behaving mice. Using a MEMS scanner and a micro-ring resonator-based ultrasonic detector, our device has achieved dynamic monitoring of cerebrovascular function (1 Hz frame rate) at high resolution (3.2 μm laterally, <20 μm axially) over a large field of view (500 μm × 500 μm). This technique opens new possibilities for studying neurovascular dynamics under natural behavior.