Photoacoustic correlation technique for low-speed flow measurement

Area of Science:

• Biophysics
• Spectroscopy
• Fluid Dynamics

Background:

• Fluorescence correlation spectroscopy (FCS) is a powerful tool for studying molecular dynamics.
• Acoustic signal detection offers an alternative to optical methods for probing dynamics.
• Characterizing low-speed fluid flow is crucial in various scientific and medical fields.

Purpose of the Study:

• To introduce and validate a new photoacoustic correlation spectroscopy (PACS) technique.
• To demonstrate PACS's capability for measuring the flow of light-absorbing particles.
• To explore potential applications of PACS in biological fluid dynamics.

Main Methods:

• Developed a photoacoustic correlation spectroscopy (PACS) system utilizing a pulsed laser and polymer microring resonators.
• Detected photoacoustic signals generated by light-absorbing beads.
• Processed signals to obtain autocorrelation curves and measure flow speeds.

Main Results:

• Successfully demonstrated proof-of-concept for PACS with flow measurements.
• Achieved temporal resolution of 0.8 seconds.
• Measured flow speeds ranging from 249 to 15.1 micrometers/second with high accuracy.

Conclusions:

• PACS is a viable technique for characterizing fluid dynamics, analogous to FCS.
• The system's low-speed flow measurement capability holds promise for detecting microcirculation, such as blood flow in capillaries.
• PACS offers a new avenue for studying the dynamics of photoacoustic materials.