Photoacoustic Doppler Effect from Flowing Small Light-Absorbing Particles

Department of Biomedical Engineering, Washington University in St. Louis, San Luis, Missouri, United States
Physical Review Letters (Impact Factor: 7.51). 12/2007; 99(18):184501. DOI: 10.1103/PhysRevLett.99.184501
Source: PubMed


From the flow of a suspension of micrometer-scale carbon particles, the photoacoustic Doppler shift is observed. As predicted theoretically, the observed Doppler shift equals half of that in Doppler ultrasound and does not depend on the direction of laser illumination. This new physical phenomenon provides a basis for developing photoacoustic Doppler flowmetry, which can potentially be used for detecting fluid flow in optically scattering media and especially low-speed blood flow of relatively deep microcirculation in biological tissue.

Download full-text


Available from: Konstantin Maslov
  • Source
    • "The term photoacoustic eeect, also called thermoacoustic eeect, refers to the generation of sound waves thermoelastically induced by light [1] [2], microwave [3] [4], or recently proposed magnetic illumination [5], in terms of pulse mode [6], continuous mode [7] [8], or resonant mode [9] [10]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Photoacoustic sensing and imaging techniques have experienced tremendous research progress, ranging from fundamental physics and methodologies to various biomedical and clinical applications in recent years. However, the state-of-art photoacoustic systems still suffer from high cost and bulky size, which hinders their potential applications for low-cost and portable diagnostics. In this paper, we propose the design for a palm-size photoacoustic sensor prototype. The design’s lower cost and smaller size would allow it to be used for portable photoacoustic sensing applications like oxygen saturation and temperature. By converting the high-frequency photoacoustic pulse signal to low-frequency photoacoustic DC signal through a rectifier circuit, the proposed photoacoustic receiver could potentially reduce the cost and device size efficiently, compared with the conventional highspeed data acquisition card interfaced with computer solutions. Preliminary testing is demonstrated to show its feasibility for photoacoustic sensing applications.
    Full-text · Article · Jan 2015
  • Source
    • "Currently, except for blood flow speed, PACT can measure all the other parameters required for quantifying MRO 2 , namely vessel cross-section, oxygen saturation and total concentration of hemoglobin, and tissue volume. Recently, a few PA methods have been proposed for blood flow measurement in deep tissue, which may be applicable to PACT (Brunker and Beard, 2010; Fang et al., 2007; Sheinfeld and Eyal, 2012; Sheinfeld et al., 2010). Therefore, PACT has the potential to simultaneously image the two metabolic pathways: oxygen metabolism as described by others, and glucose metabolism as shown in this paper. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We have demonstrated the feasibility of imaging mouse brain metabolism using photoacoustic computed tomography (PACT), a fast, noninvasive and functional imaging modality with optical contrast and acoustic resolution. Brain responses to forepaw stimulations were imaged transdermally and transcranially. 2-NBDG, which diffuses well across the blood-brain-barrier, provided exogenous contrast for photoacoustic imaging of glucose response. Concurrently, hemoglobin provided endogenous contrast for photoacoustic imaging of hemodynamic response. Glucose and hemodynamic responses were quantitatively decoupled by using two-wavelength measurements. We found that glucose uptake and blood perfusion around the somatosensory region of the contralateral hemisphere were both increased by stimulations, indicating elevated neuron activity. While the glucose response area was more homogenous and confined within the somatosensory region, the hemodynamic response area had a clear vascular pattern and spread wider than the somatosensory region. Our results demonstrate that 2-NBDG-enhanced PACT is a promising tool for noninvasive studies of brain metabolism.
    Full-text · Article · Aug 2012 · NeuroImage
  • Source
    • "Image contrast is dominated by optical absorption making it well suited for imaging the vasculature due to the strong optical absorption of hemoglobin. As well as imaging vascular anatomy, functional information in the form of blood oxygenation and flow can be obtained: the former by acquiring images at multiple wavelengths and exploiting the spectral differences between oxy and deoxyhemoglobin [2,3], the latter by extracting the acoustic Doppler shift encoded on to photoacoustic waves emitted by moving red blood cells [4–6]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: A noninvasive, multimodal photoacoustic and optical coherence tomography (PAT/OCT) scanner for three-dimensional in vivo (3D) skin imaging is described. The system employs an integrated, all optical detection scheme for both modalities in backward mode utilizing a shared 2D optical scanner with a field-of-view of ~13 × 13 mm(2). The photoacoustic waves were detected using a Fabry Perot polymer film ultrasound sensor placed on the surface of the skin. The sensor is transparent in the spectral range 590-1200 nm. This permits the photoacoustic excitation beam (670-680 nm) and the OCT probe beam (1050 nm) to be transmitted through the sensor head and into the underlying tissue thus providing a backward mode imaging configuration. The respective OCT and PAT axial resolutions were 8 and 20 µm and the lateral resolutions were 18 and 50-100 µm. The system provides greater penetration depth than previous combined PA/OCT devices due to the longer wavelength of the OCT beam (1050 nm rather than 829-870 nm) and by operating in the tomographic rather than the optical resolution mode of photoacoustic imaging. Three-dimensional in vivo images of the vasculature and the surrounding tissue micro-morphology in murine and human skin were acquired. These studies demonstrated the complementary contrast and tissue information provided by each modality for high-resolution 3D imaging of vascular structures to depths of up to 5 mm. Potential applications include characterizing skin conditions such as tumors, vascular lesions, soft tissue damage such as burns and wounds, inflammatory conditions such as dermatitis and other superficial tissue abnormalities.
    Full-text · Article · Aug 2011 · Biomedical Optics Express
Show more