Hydrogel Fluorescence Microsensor with Fluorescence Recovery for Prolonged Stable Temperature Measurements

Area of Science:

• Biomedical Engineering
• Materials Science
• Optical Sensing

Background:

• Optical microsensors offer promising temperature measurement for cells and environments.
• Photobleaching of fluorescent dyes limits stability in conventional optical sensing.
• Developing stable microsensors is crucial for prolonged biological and environmental monitoring.

Purpose of the Study:

• To develop a hydrogel fluorescence microsensor with enhanced stability for prolonged temperature measurements.
• To propose and validate a photobleaching compensation method utilizing fluorescent dye diffusion within a hydrogel matrix.
• To investigate factors influencing compensation, including measurement intervals, materials, and microsensor composition.

Main Methods:

• A photobleaching compensation method based on fluorescent dye diffusion in hydrogel microsensors was proposed.
• Hydrogel and polystyrene microsensors (20 µm diameter) were fabricated and compared.
• Factors like measurement interval, material composition (9% PEGDA 575, 2% photoinitiator), and microsensor size were systematically evaluated.

Main Results:

• The optimized hydrogel microsensor demonstrated excellent fluorescence intensity stability (within 1% SD after 100 measurements).
• Larger hydrogel microsensors showed minimal fluorescence decrease (within 3% after 900 measurements).
• Temperature measurements showed high accuracy, with maximum error and SD of 0.5 °C and 0.3 °C compared to a thermopile over 5400 s.

Conclusions:

• The proposed hydrogel fluorescence microsensor effectively compensates for photobleaching, enabling stable, prolonged temperature measurements.
• The dye diffusion method significantly enhances sensor longevity and reliability for various applications.
• This technology holds potential for advanced in-situ monitoring in biological and environmental systems.