(a) The Acoustic-Resolution Photoacoustic Microscopy system is built and used for imaging the skin vasculature. (b) The AR-PAM reconstruction of the skin capillary network is shown[3].

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... melanin, is reconstructed. This technical feature is used to determine whether to biopsy the skin lesions on the patients with suspected invasive squamous cell carcinoma [26]. The Acoustic-Resolution Photoacoustic Microscopy (AR-PAM) is built and brought into the clinical scenario of investigating the vessel distribution in the skin/lesion (see Fig. 3(a)). The spatial resolution of the PAT is similar to that of the OCT, namely, 3 to 5µm. In this establishment, a microscopic alignment is built to distribute laser pulses on the defined acoustic focus. Meanwhile, a mechanical wave transducer is synchronized to receive the generated acoustic signal from the acoustic focus. The AR-PAM ...

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... a mechanical wave transducer is synchronized to receive the generated acoustic signal from the acoustic focus. The AR-PAM reconstructs the blood perfusing vessels with better contrast and sharpness than the sOCT. Additionally, a functional reconstruction of the tissue oximetry parameters based on the optical absorption spectra can be given (see Fig. 3(b)). However, like all other photoacoustic approaches, the imaging procedure is relatively slow due to the transducer scanning speed and the repetition rate of the pulsed laser. Also, it is computationally very complex to derive the generation and propagation of the acoustic wave in an acoustically homogeneous inviscid medium from the ...

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... at the wavelength of 960nm. The water-equivalence is found in the spectral feature of the PBS buffer prepared, which shows an absorption peak at 960nm as well. Some minor absorption peaks in the visible range from 400 to 600nm are missing from the PBS spectra, whereby the real water gives low absorption peaks around the wavelength of 585nm (see Fig. 30 To obtain the f PF spectra of the pure PBS buffer, individual absorbance quantification is done to calculate the f PF values at each single wavelength. The molar attenuation coefficient is first calculated from the observed transmission and reflectance. With the transmittance spectra and the reflectance spectra quantified through the ...

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... and the reflectance spectra quantified through the Inverse Adding Doubling method, the molar attenuation coefficient spectra are computed. By dividing the absorbance spectrum by the molar attenuation spectrum, the f PF spectrum of the PBS buffer is plotted. At 537 and 577nm, the f PF values of the PBS are 1.0336 and 1.0339 respectively (see Fig. 30(b)). In brief, the PBS is exhibiting high optical transparency and a spectral similarity to that of the real water. Intralipid is used to simulate the lipid that exists in the human whole blood, in the form of its dilution in the PBS buffer, and its optical absorbance is quantified. The absorbance spectra of the intralipid dilution are ...

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... means, the binding affinity of the hemoglobin to O 2 is optimized under a relatively high PH value. In figure 33(a) and (b), the optical path length factors of the oxygenated and deoxygenated dilutions at the concentration of 10 g/L are shown. Like the case for the intralipid dilution and the PBS buffer, the optical path length factor of the corresponding hemoglobin sample is calculated from the absorbance/reflectance data. ...

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... prototype optofluidic in-vitro microphysiological vascular phantom containing the in-/outlet and 4 separate rows of hollow microchannels is prepared and shown (finished sample see Fig. 34(a) and (b), schematic and photo see Fig. 34(c)). The diameter and the depth of the microchannels are measured separately on the finished optofluidic phantom by using an SD-OCT (Telesto-II-SP1, Thorlabs GmbH, Germany). As shown in these images, the inlet and outlet mimic respectively the arteries and veins, while the microchannels mimic ...

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... prototype optofluidic in-vitro microphysiological vascular phantom containing the in-/outlet and 4 separate rows of hollow microchannels is prepared and shown (finished sample see Fig. 34(a) and (b), schematic and photo see Fig. 34(c)). The diameter and the depth of the microchannels are measured separately on the finished optofluidic phantom by using an SD-OCT (Telesto-II-SP1, Thorlabs GmbH, Germany). As shown in these images, the inlet and outlet mimic respectively the arteries and veins, while the microchannels mimic the microvasculature. In order to check the ...

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... on the finished optofluidic phantom by using an SD-OCT (Telesto-II-SP1, Thorlabs GmbH, Germany). As shown in these images, the inlet and outlet mimic respectively the arteries and veins, while the microchannels mimic the microvasculature. In order to check the vessel geometry uniformity more directly, the OCT is used for a 3D reconstruction (see Fig. 34(e) and (f)). The measured value of the microchannel width is 52µm on average. Overall, the reconstructed optofluidic structure matches the original intention of the optofluidic design given in Fig. 20 in the shape and ...

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... phantom optical properties are presented in the µ a against µ s , of the PU matrices from different optofluidic phantom slabs. The paradigm of the µ a and µ s , are first attained from the ex-vivo skin slabs at the wavelengths of 500, 600, 700nm, and 900nm [16,17,18]. The results are seen in Fig. 35. It is expected to find a significant similarity within a comparison of the optical properties of the optofluidic phantom matrices to those of the ex-vivo human cutis. Whether the measured µ a and µ s , values could cover the reference va-lues is the key question. The measured values are displayed in black dots. The paradigm zone ...

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... 600 nm, the µ a of the PU slab gives a variance from 0.1 to 1.91 mm −1 . This range covers the paradigm from the real tissue, which gives a variance from 0.23 to 1.61 mm −1 . The µ s , values show the same coverage. Similar coverage can be found at 700 and 1000nm, where the sampling zone of the µ a and µ s , overlaps with the paradigm zone (see Fig. 35). An exception can be found at 500nm, at which the sampling zone does not cover the paradigm zone (see Fig. 35(a)). This is due to the fact that the reference values are mostly attained from the blood perfused tissue as reported. The ex-vivo tissue sample contains residual blood in the ECM, which induces an increasing absorption at ...

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... the real tissue, which gives a variance from 0.23 to 1.61 mm −1 . The µ s , values show the same coverage. Similar coverage can be found at 700 and 1000nm, where the sampling zone of the µ a and µ s , overlaps with the paradigm zone (see Fig. 35). An exception can be found at 500nm, at which the sampling zone does not cover the paradigm zone (see Fig. 35(a)). This is due to the fact that the reference values are mostly attained from the blood perfused tissue as reported. The ex-vivo tissue sample contains residual blood in the ECM, which induces an increasing absorption at 500nm compared to that of the PU phantom matrices with no blood fraction. In brief, the optical turbidities of the ...

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... continuous chemical reaction occurs at the solid-liquid (electrolyte-PU) interface and changes the optical properties of the PU surface. To characterize the possible changes in the optical properties, the optical parameters of the phantom matrices are investigated before and after the PU slabs are attached to the electrolysis for 96 hours (see Fig. 36). PU slabs with different amount of TiO 2 and india ink are prepared into 200µm slabs for this study. Figure 36 summarizes the attenuation rate in the total transmittance T t , the diffuse transmittance T d , the absorbance A b , and the diffuse reflectance R d before and after etching. The Z-axis indicates the projection of the ...

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... slabs with different amount of TiO 2 and india ink are prepared into 200µm slabs for this study. Figure 36 summarizes the attenuation rate in the total transmittance T t , the diffuse transmittance T d , the absorbance A b , and the diffuse reflectance R d before and after etching. The Z-axis indicates the projection of the normalized values. ...

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... prototype elastofluidic in-vitro microphysiological vascular phantom with a minimum amount of scatterers in the superstrate is demonstrated to highlight the layout of the elastofluidic structure. Figure 37 (b) and (c) demonstrate the top-views of the elastofluidic channels and the resolution targets. It is expected to read 200µm in the channel width for the hi-flow speed and the mid-flow speed channels and 100µm for the diffusion channel. ...

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... mentioned geometries are measured again with the help of a Laser Scanning Microscope (LSM) (LEXT OLS4000, Olympas co., Japan). As the result of the LSM study, of which the phantom superstrate is peeled-off, a sharper picture is given without any optical disruption from the light scattering in the phantom matrices (see Fig.37). Regarding the changes in the surface tension of the PVCp material during its polymerization, the cross-sectional widths of the channels are around 207µm and 93µm respectively. ...

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... measured thickness of the PVCp superstrate is around 213µ m, which is slightly overriding the designed value of 200µ m. The resolution targets show 4 triangular quarters surrounding a rhombus shape in the center (see Fig.37(b)). A minimum dimension of the elastofluidic structure is found at the gap between the rhombus diagonal corner and the square, where 21µm is registered for the gap size. ...

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... triangular quarters surrounding a rhombus shape in the center (see Fig.37(b)). A minimum dimension of the elastofluidic structure is found at the gap between the rhombus diagonal corner and the square, where 21µm is registered for the gap size. The cross-sectional views of the microchannels and the inlets are also given in the OCT 2D B-Scans (see Fig. 38(a) and (b)). Same specifications are measured and show unity in the cross-sectional width obtained in the top-views. Under the depress liquid pressure given by the membrane pump (up to 6 bar), the elastic PVCp matrices start to spread out horizontally (see Fig.38(b)). This simulates the vessel expansion under the flush of blood from ...

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... specifications are measured and show unity in the cross-sectional width obtained in the top-views. Under the depress liquid pressure given by the membrane pump (up to 6 bar), the elastic PVCp matrices start to spread out horizontally (see Fig.38(b)). This simulates the vessel expansion under the flush of blood from the systolation. ...

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... optical properties of the elastofluidic phantom matrices are first compared to those of the optofluidic phantom matrices (see Fig. 39). As the result, the µ a and µ s , approach each other in the diagram. This means, the switch in the material selection of the phantom matrices from the castable polyurethane to the elastomer PVCp does not bring severe changes in the optical properties, although these two materials show slight differences in their refractive index N at ...

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... directly on the human volunteers without any forecast of the chromophores' heterogeneity from the phantom validations, they could not realize the erroneous results from the in-vivo experiments. In this study, the existence of the fibroblasts and the inhomogeneous spatial distribution of the major chromophores in the in-vivo human skin (see Fig. 43) should be replicated in the in-vitro phantom matrices. The fibroblasts cause the anisotropy in the propagation of light along their fiberized structure. When light is incident perpendicular to the fibroblasts, backward scattering/reflectance becomes dominating. They block the incident light from propagating forward to reach the deeper ...

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... SO 2measured /SO 2real values are re-calculated based on the compensation. A comparison of the recovered oxygenation parameters before and after the compensation is given in Fig.53. The results are re-plotted based on the established raw data, where a 30% distinction between the SO 2measured and the SO 2real is found before the compensation. ...