Compact Laser-Induced Fluorescence Detector with Adjustable Laser Focal Spot for Multiple Purposes

Area of Science:

• Analytical Chemistry
• Biophotonics
• Instrumentation Engineering

Background:

• Increasing demand for miniaturized laser-induced fluorescence (LIF) detection systems across research fields.
• Need for adaptable detection systems for diverse targets like capillaries, PCR tubes, and microfluidic chips.

Purpose of the Study:

• To develop a compact, cost-effective, and highly sensitive LIF detector.
• To optimize excitation source, wavelength, and power for enhanced detection limits.
• To demonstrate the detector's integration and performance in various analytical systems, including space applications.

Main Methods:

• Development of a compact LIF detector using a laser diode and photodiode with adjustable focal spot.
• Implementation of background fluorescence correction, adaptive dynamic range adjustment, and constant laser power control.
• Experimental investigation of excitation power's influence on detection limits and optimization of light source (LED/LD) and wavelength (487/450 nm).

Main Results:

• Construction of a fully integrated, modular epifluorescence LIF detector (40 × 22 × 38 mm³) costing USD 320.
• Achieved a detection limit of 0.4 nM for fluorescein sodium.
• Successful integration into a nucleic acid detection system on the Chinese Space Station (CSS) and testing with PCR tubes and capillaries.

Conclusions:

• The developed compact LIF detector meets the demand for miniaturized analytical systems.
• The system demonstrates broad practicality, adaptability, and high sensitivity for diverse applications.
• This technology holds potential for advanced molecular detection in various environments, including space exploration.