Cross-correlation-based transverse flow measurements using optical resolution photoacoustic microscopy with a digital...

Area of Science:

• Biomedical Optics
• Photoacoustic Imaging
• Microfluidics

Background:

• Quantitative measurement of transverse flow velocity is crucial for understanding biological processes.
• Existing methods may have limitations in accuracy, resolution, or applicability to biological tissues.

Purpose of the Study:

• To develop and validate a novel cross-correlation-based method for measuring transverse flow velocity.
• To enhance optical resolution photoacoustic microscopy with a digital micromirror device for flow velocimetry.
• To assess the accuracy, range, and biological tissue applicability of the proposed technique.

Main Methods:

• Utilized optical resolution photoacoustic (PA) microscopy integrated with a digital micromirror device (DMD).
• Employed a cross-correlation analysis of PA signals generated by two spatially separated, alternately delivered laser beams.
• Measured transverse flow velocity in microsphere suspensions and biological tissue models.

Main Results:

• Successfully measured transverse flow velocities ranging from 0.50 to 6.84 mm/s with a root-mean-squared accuracy of 0.22 mm/s.
• Demonstrated flow measurement independence from particle size for velocities between 0.55 and 6.49 mm/s.
• Achieved an accuracy of 0.35 mm/s at a 0.3 mm depth in chicken breast tissue.

Conclusions:

• The proposed cross-correlation PA microscopy method accurately quantifies transverse flow speed and direction.
• The technique is robust across different particle sizes and shows potential for in vivo applications.
• This method offers a promising tool for non-invasive flow velocity measurements in biological tissues.