Optically trapped microsensors for microfluidic temperature measurement by fluorescence lifetime imaging microscopy

Area of Science:

• Biophysics
• Microfluidics
• Optical Physics

Background:

• Accurate temperature measurement is crucial for microfluidic applications.
• Traditional methods often require invasive probes or bulk dye introduction, complicating analysis.
• Fluorescence lifetime imaging microscopy (FLIM) offers quantitative imaging capabilities.

Purpose of the Study:

• To develop a non-invasive method for precise temperature measurement within microfluidic devices.
• To integrate optical tweezers with FLIM for localized temperature sensing.
• To utilize novel temperature-sensitive fluorescent microprobes for enhanced accuracy.

Main Methods:

• Combining optical tweezers with fluorescence lifetime imaging microscopy (FLIM).
• Employing specially developed temperature-sensitive fluorescent microprobes (Rhodamine B).
• Encapsulating the fluorophore within a double-bubble microdroplet (aqueous core, oil shell) for optical trapping and manipulation.

Main Results:

• Successful non-invasive, quantitative mapping of temperature distribution in microfluidic channels.
• Demonstrated the ability to manipulate and hold temperature-sensitive microdroplets using optical tweezers.
• Validated the approach without the need for a pervasive fluorescent dye within the microfluidic system.

Conclusions:

• The combined optical tweezers and FLIM technique provides a powerful tool for microfluidic temperature analysis.
• This method offers high spatial resolution and avoids sample contamination or alteration.
• The microdroplet encapsulation strategy is effective for targeted sensing in microfluidic environments.