Three-dimensional confocal Raman temperature characterization of electrokinetically pumped microchannels

Area of Science:

• Physics
• Chemistry
• Engineering

Background:

• Accurate temperature measurement is crucial for understanding microfluidic device performance.
• Previous methods often lack 3D capabilities or require complex spectral analysis.

Purpose of the Study:

• To present a novel, noninvasive method for three-dimensional temperature characterization in microfluidic devices.
• To enable precise thermal profiling in microscale systems.

Main Methods:

• A custom confocal microscope was utilized to measure water temperature via Raman spectrum variations.
• The method involves splitting the spectrum at the isosbestic point and using two photon counters.
• A linear relationship between the normalized signal difference and temperature was established.

Main Results:

• Achieved 0.8 K temperature precision and 9 μm axial resolution with 1 s integration time.
• Demonstrated 3D temperature profiling, overcoming limitations of previous 2D methods.
• Identified heat flow through the glass coverslip as the dominant heat dissipation mechanism in polydimethylsiloxane microchannels.

Conclusions:

• The novel Raman spectroscopy-based method provides accurate and high-resolution 3D temperature measurements in microfluidic devices.
• This technique offers significant advantages over existing methods for thermal analysis in microchannels.
• The findings are consistent with existing literature, validating the new approach.