Time-resolved spectroscopy at 19,000 lines per second using a CMOS SPAD line array enables advanced biophotonics...

Area of Science:

• Photonics and Spectroscopy
• Biomedical Optics
• Materials Science

Background:

• Time-resolved fluorescence spectra (TRFS) are crucial for analyzing dynamic molecular processes.
• Existing TCSPC systems face limitations in acquisition speed and flexibility.
• Advancements in SPAD sensor technology offer potential for faster and more versatile spectral measurements.

Purpose of the Study:

• To develop and present a novel SPAD-based line sensor for ultra-fast TRFS acquisition.
• To enhance existing TCSPC capabilities with parallelized interfaces and digital time-gating.
• To demonstrate the sensor's performance across various spectroscopic applications.

Main Methods:

• Fabrication of a SPAD-based line sensor using 130 nm CMOS technology.
• Implementation of a parallelized interface for high line rate data transfer (19,000 lines/s).
• Development of a novel digital time-gating architecture rejecting photons in the OFF region.
• On-chip center-of-mass (CMM) calculations for direct lifetime estimation.

Main Results:

• Achieved the fastest reported TRFS acquisition to date at 8.3 milliseconds.
• Demonstrated high line rate capability enabling rapid data acquisition.
• Successfully applied the sensor to time-gated TRFS of chlorophyll A, FRET probes, and lung tissue autofluorescence.
• Showcased time-gated Raman spectroscopy of toluene.
• Achieved spectrally resolved detection of fast chlorophyll A fluorescence lifetime transients.

Conclusions:

• The developed SPAD-based line sensor represents a significant advancement in TRFS acquisition speed and versatility.
• The novel time-gating and on-chip CMM capabilities offer powerful tools for researchers.
• The system's performance empowers widespread applications in spectroscopy, biosensing, and biomedical imaging.