Fast temperature measurement following single laser-induced cavitation inside a microfluidic gap

Area of Science:

• Physics
• Biophysics
• Microfluidics

Background:

• Laser-induced microbubbles are utilized in microfluidics for liquid actuation, biological material interaction, and medical diagnostics.
• Previous studies lacked the temporal resolution to measure microbubble collapse-induced heating.
• Microbubble radius typically ranges from 10-35 µm.

Purpose of the Study:

• To measure the spatial temperature profile evolution following laser-induced microbubble collapse.
• To extend the limits of non-invasive fluorescence thermometry for high-speed measurements.

Main Methods:

• Utilized high-speed video recording at up to 90,000 frames per second.
• Employed non-invasive fluorescence thermometry.
• Imaged spatial temperature profiles using a fluorescence microscope.

Main Results:

• Observed moderate temperature rises (< 12.8°C).
• Temperature increases were localized (< 15 µm) and short-lived (< 1.3 ms).
• Significant differences in temperature evolution were noted between microfluidic gaps and unbounded containers due to jetting and bubble migration.

Conclusions:

• The study quantifies temperature changes associated with laser-induced microbubbles.
• Results validate the safety of current applications involving laser pulses and photothermal bubbles in various liquid environments.
• Understanding bubble dynamics is crucial for optimizing microfluidic and biomedical applications.