Photoacoustic thermal flowmetry with a single light source.

Published

Journal Article

We report a photoacoustic thermal flowmetry based on optical-resolution photoacoustic microscopy (OR-PAM) using a single laser source for both thermal tagging and photoacoustic excitation. When an optically absorbing medium is flowing across the optical focal zone of OR-PAM, a small volume of the medium within the optical focus is repeatedly illuminated and heated by a train of laser pulses with a high repetition rate. The average temperature of the heated volume at each laser pulse is indicated by the photoacoustic signal excited by the same laser pulse due to the well-established linear relationship between the Grueneisen coefficient and the local temperature. The thermal dynamics of the heated medium volume, which are closely related to the flow speed, can therefore be measured from the time course of the detected photoacoustic signals. Here, we have developed a lumped mathematical model to describe the time course of the photoacoustic signals as a function of the medium's flow speed. We conclude that the rising time constant of the photoacoustic signals is linearly dependent on the flow speed. Thus, the flow speed can be quantified by fitting the measured photoacoustic signals using the derived mathematical model. We first performed proof-of-concept experiments using defibrinated bovine blood flowing in a plastic tube. The experiment results have demonstrated that the proposed method has high accuracy (∼±6%) and a wide range of measurable flow speeds. We further validated the method by measuring the blood flow speeds of the microvasculature in a mouse ear in vivo.

Full Text

Duke Authors

Cited Authors

  • Liu, W; Lan, B; Hu, L; Chen, R; Zhou, Q; Yao, J

Published Date

  • September 2017

Published In

Volume / Issue

  • 22 / 9

Start / End Page

  • 1 - 6

PubMed ID

  • 28875623

Pubmed Central ID

  • 28875623

Electronic International Standard Serial Number (EISSN)

  • 1560-2281

International Standard Serial Number (ISSN)

  • 1083-3668

Digital Object Identifier (DOI)

  • 10.1117/1.jbo.22.9.096001

Language

  • eng