Fully Integrated Time-Gated 3D Fluorescence Imager for Deep Neural Imaging

Area of Science:

• Biomedical Engineering
• Optical Imaging
• Neuroscience

Background:

• Deep brain fluorescence imaging is crucial for neuroscience research.
• Existing methods face challenges with scattering and background autofluorescence.
• Need for high-resolution, minimally invasive imaging techniques.

Purpose of the Study:

• To develop and characterize a compact time-gated fluorescence imager for deep brain applications.
• To demonstrate the system's capability for high-resolution 3D imaging and background suppression.
• To evaluate the device's potential for in vivo neuroscience studies.

Main Methods:

• Utilized on-chip laser diodes and single-photon avalanche diodes (SPADs) for pulsed excitation and detection.
• Implemented time-gating of SPADs for fluorescence excitation rejection (O.D. 3 at 1 ns).
• Employed Talbot gratings for mapping 2D photon counts to 3D images.

Main Results:

• Achieved 3D image resolution of 40 μm (x), 35 μm (y), and 73 μm (z) in a noiseless environment.
• Maximum frame rate of 50 kilo-frames-per-second.
• Successfully resolved a micropipette with fluorescent microspheres, demonstrating imaging capability.

Conclusions:

• The developed time-gated fluorescence imager offers high resolution and significant background rejection for deep brain imaging.
• Its compact design (420 μm width) allows deep brain insertion with a wide field of view.
• This technology holds promise for advancing in vivo neuroscience research and diagnostics.