A 65k pixel, 150k frames-per-second camera with global gating and micro-lenses suitable for fluorescence lifetime...

Area of Science:

• Photonics and Imaging
• Solid-State Devices
• Biophysics

Background:

• Advancements in CMOS technology enable the development of high-resolution, high-speed imaging sensors.
• Single-photon avalanche diodes (SPADs) offer high sensitivity for detecting single photons.
• Fluorescence Lifetime Imaging (FLIM) is a powerful technique for analyzing biological samples and materials.

Purpose of the Study:

• To develop and characterize a 65k-pixel SPAD-based imaging sensor for high-speed applications.
• To demonstrate the sensor's capability for Fluorescence Lifetime Imaging (FLIM) with high temporal resolution.
• To evaluate the sensor's performance in measuring fluorescence lifetimes of various fluorophores.

Main Methods:

• Fabrication of a 65k-pixel SPAD sensor using a 0.35μm standard CMOS process.
• Implementation of a 12T quenching and gating circuitry per pixel for precise timing control.
• Synchronization of the sensor's illumination period with a picosecond laser for FLIM measurements.
• Development of FPGA-based control and real-time computation, with USB2 communication.

Main Results:

• Achieved a sensor readout speed of 6.4μs, enabling over 150k monochrome frames per second.
• Demonstrated Fluorescence Lifetime Imaging (FLIM) with an accuracy better than 100 picoseconds.
• Successfully measured fluorescence lifetimes of different fluorophores ranging from 150 picoseconds to 5 nanoseconds.

Conclusions:

• The developed 65k-pixel SPAD sensor is suitable for high-speed imaging and advanced applications like FLIM.
• The sensor's precise gating and readout capabilities facilitate accurate lifetime measurements.
• This technology opens possibilities for advanced research in biophysics, material science, and other fields requiring high-temporal-resolution imaging.