Fluorescence ratio thermometry in a microfluidic dual-beam laser trap

Area of Science:

• Optical trapping
• Microfluidics
• Thermal analysis

Background:

• Dual-beam laser traps are essential tools in various scientific fields.
• Understanding thermal properties is critical for optimizing microfluidic trap performance.
• Existing methods for thermal characterization can be intrusive or lack spatial resolution.

Purpose of the Study:

• To develop and validate a non-intrusive fluorescence ratio technique for characterizing thermal properties of microfluidic laser traps.
• To measure temperature distribution profiles within a microfluidic trap geometry.
• To compare experimental temperature measurements with simulated distributions.

Main Methods:

• Utilized a dual-beam laser trap in a microfluidic setup.
• Employed a non-intrusive fluorescence ratio technique with Rhodamine B (temperature-sensitive) and Rhodamine 110 (temperature-independent) dyes.
• Performed measurements using confocal laser-scanning microscopy for submicron spatial resolution.

Main Results:

• Successfully measured temperature distribution profiles within the microfluidic trap.
• Determined maximum heating of (13 +/- 2) degrees C/W at 1064 nm wavelength in the trap center.
• Observed a linear scaling of temperature increase with applied laser power.
• Experimental results showed good agreement with simulated temperature distributions.

Conclusions:

• The developed fluorescence ratio technique provides accurate, non-intrusive thermal characterization of microfluidic laser traps.
• The findings offer valuable data for optimizing laser trap designs and applications in microfluidics.
• This method enables precise temperature mapping, essential for sensitive microscale experiments.