Photoacoustic signal dependence on sample-backing thermal resistance

2001 ◽  
Vol 37 (1) ◽  
pp. 77-80
Author(s):  
R. J. Bukowski ◽  
A. Domanowska
Keyword(s):  
Thermal Resistance ◽  
Photoacoustic Signal ◽  
Signal Dependence

Investigation of the photoacoustic signal dependence on laser power

2007 ◽  
Author(s):  
Jan Niemi ◽  
Torbjörn Löfqvist ◽  
Per Gren
Keyword(s):  
Laser Power ◽  
Photoacoustic Signal ◽  
Signal Dependence

scholarly journals Photoacoustics of core–shell nanospheres using comprehensive modeling and analytical solution approach

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Khosro Shahbazi ◽  
Wolfgang Frey ◽  
Yun-Sheng Chen ◽  
Salavat Aglyamov ◽  
Stanislav Emelianov
Keyword(s):  
Analytical Solution ◽  
Thermal Resistance ◽  
Imaging Techniques ◽  
Silica Coating ◽  
Photoacoustic Signal ◽  
Interfacial Thermal Resistance ◽  
Core Shell ◽  
Contrast Imaging ◽  
Solution Approach ◽  
The Impact

Abstract Photoacoustic visualization of nanoparticles is capable of high contrast imaging at depth greater than that of traditional optical imaging techniques. Identifying the impact of various parameters on the photoacoustic signal is crucial in the design of effective medical imaging and diagnostics. Here, we develop a complete model of Fourier heat conduction incorporating the interfacial thermal resistance and photoacoustic equation for core-shell nanospheres in a fluid under nanosecond pulsed laser illumination. An analytical solution is obtained, elucidating the contribution of each region (core, shell, or the fluid) in the generation of the photoacoustic signal. The model reveals that the sharper the laser pulse temporal waveform is, the higher the sensitivity of the generated photoacoustic signal will be to the interfacial thermal resistance, and, thus, the higher the possibility of photoacoustic signal amplification will be using silica-coating. The comprehensive model and adopted analytical solution reveal the underlying physics of the photoacoustic signal generation  form core-shell nanosphere systems.

scholarly journals Photoacoustic Properties of Polypyrrole Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2457
Author(s):  
Peter Keša ◽  
Monika Paúrová ◽  
Michal Babič ◽  
Tomáš Heizer ◽  
Petr Matouš ◽  
...  
Keyword(s):  
Contrast Agent ◽  
Photoacoustic Imaging ◽  
Particle Surface ◽  
Photoacoustic Signal ◽  
Ammonium Persulphate ◽  
Coated Nanoparticles ◽  
Polypyrrole Nanoparticles ◽  
Signal Dependence

Photoacoustic imaging, an emerging modality, provides supplemental information to ultrasound imaging. We investigated the properties of polypyrrole nanoparticles, which considerably enhance contrast in photoacoustic images, in relation to the synthesis procedure and to their size. We prepared polypyrrole nanoparticles by water-based redox precipitation polymerization in the presence of ammonium persulphate (ratio nPy:nOxi 1:0.5, 1:1, 1:2, 1:3, 1:5) or iron(III) chloride (nPy:nOxi 1:2.3) acting as an oxidant. To stabilize growing nanoparticles, non-ionic polyvinylpyrrolidone was used. The nanoparticles were characterized and tested as a photoacoustic contrast agent in vitro on an imaging platform combining ultrasound and photoacoustic imaging. High photoacoustic signals were obtained with lower ratios of the oxidant (nPy:nAPS ≥ 1:2), which corresponded to higher number of conjugated bonds in the polymer. The increasing portion of oxidized structures probably shifted the absorption spectra towards shorter wavelengths. A strong photoacoustic signal dependence on the nanoparticle size was revealed; the signal linearly increased with particle surface. Coated nanoparticles were also tested in vivo on a mouse model. To conclude, polypyrrole nanoparticles represent a promising contrast agent for photoacoustic imaging. Variations in the preparation result in varying photoacoustic properties related to their structure and allow to optimize the nanoparticles for in vivo imaging.

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