Cortical blood flow imaging with a portable MEMS based 2-photon fluorescence microendoscope

We present a portable microendoscope based on a microelectromechanical systems (MEMS) scanner, compound gradient refractive index micro-lenses and a photonics bandgap fiber (PBF). It overcomes the size (2.0 × 1.9 × 1.1 cm ³ ) and weight (less than 3 grams) limitations of conventional two-photon fluorescence microscopy toward freely moving subjects. The microendoscope utilizes a photonic bandgap fiber for laser excitation and large core fiber for fluorescence collection. We demonstrated cortical blood flow imaging in live mice with transverse (Δx) and axial resolutions (Δz) of 1.6 μm and 13.5 μm, respectively.