A lifetime-based fluorescence resonance energy transfer sensor for ammonia

Area of Science:

• Chemical Sensors
• Materials Science
• Optical Sensing

Background:

• Ammonia (NH3) detection is crucial in environmental monitoring and industrial safety.
• Developing sensitive and selective optical sensors for NH3 remains a significant challenge.
• Fluorescence-based methods offer potential for non-invasive and real-time gas sensing.

Purpose of the Study:

• To develop and characterize a lifetime-based optical sensor for ammonia detection.
• To investigate the sensor's response to varying ammonia concentrations.
• To evaluate the sensor's selectivity, humidity effects, and long-term stability.

Main Methods:

• Fabrication of an optical sensor using sulforhodamine 101 (donor) and bromocresol green (acceptor) immobilized on ethyl cellulose.
• Utilizing fluorescence resonance energy transfer (FRET) principle for ammonia sensing.
• Measurement of changes in fluorescence decay time (phase angle and modulation) using phase-modulation fluorometry.

Main Results:

• The sensor exhibited a decrease in phase angle and an increase in modulation with increasing ammonia concentration (0-175 ppm).
• Oxygen and carbon dioxide showed no interference; relative humidity caused a minor response shift.
• Fast response (1 min) and recovery (2.5 min) times were observed, with good reproducibility over 5 days.

Conclusions:

• The developed FRET-based optical sensor demonstrates effective ammonia detection capabilities.
• The sensor offers good selectivity, stability, and rapid response, making it suitable for practical applications.
• Lifetime-based fluorescence measurements provide a robust platform for developing advanced gas sensors.