Lightweight mini-endoscope for two color imaging of neural activities with large field of view

We present the design and the experimental characterization of a miniature “portable” mini-endoscope with a large field-of-view ($\approx 360rmmum$) that operates with two spectral bands adapted for mCherry (peak emission at 610 nm) and GCaMP6s (peak emission at 513 nm) fluorophores. The diameter of the implant is very small (0.5 mm), the total weight is 1.8 g, the size is $10\times 12\times 21{\mathrm{mm}}^3$, and the lateral resolution of the device is $\approx 4.5\mu m$. This compact and lightweight system allows investigation of the neural activity of two different neuronal populations.