Quantitative mapping of aqueous microfluidic temperature with sub-degree resolution using fluorescence lifetime...

Area of Science:

• Polymer Science
• Fluorescence Spectroscopy
• Microfluidics

Background:

• Accurate temperature monitoring is crucial for microfluidic applications.
• Existing methods for microfluidic temperature measurement lack sufficient resolution.
• Thermo-responsive polymers offer potential for sensitive temperature detection.

Purpose of the Study:

• To demonstrate a water-soluble, thermo-responsive polymer as a sensitive fluorescence-lifetime probe for microfluidic temperature.
• To establish the photophysical basis for the polymer's temperature response.
• To achieve high-resolution spatial mapping of temperature variations in microfluidic devices.

Main Methods:

• Utilized poly(N-isopropylacrylamide) labeled with a benzofurazan fluorophore.
• Investigated the fluorescence lifetime dependence on temperature around the polymer's phase transition.
• Employed fluorescence lifetime imaging microscopy (FLIM) for spatial temperature mapping.

Main Results:

• The polymer probe exhibited a steep fluorescence lifetime change with temperature near its phase transition.
• Established the photophysical mechanism underlying this temperature sensitivity.
• Achieved micron-scale temperature mapping with a resolution better than 0.1°C.

Conclusions:

• A novel polymer-based fluorescence-lifetime probe enables highly sensitive microfluidic temperature measurements.
• FLIM with this probe offers an order of magnitude improvement in temperature resolution compared to previous methods.
• This technique provides a powerful tool for precise thermal analysis in microfluidic systems.