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Medical optics and biotechnology|35 Article(s)
Imaging of human wrist joint by a flexible-transducer-based morphological-adaptive photoacoustic tomography: a feasibility study
Xin Wang, and Sihua Yang
In this study, the feasibility of visualization of human joints using photoacoustic tomography (PAT) is investigated. To verify this idea, the system of integrated optical fiber bundles and a custom-made flexible transducer is established, both of which give the advantage of morphological adaptation; therefore, the coupling section can be worn on human limbs. The imaging capacity of the flexible-transducer-based PAT system is validated by mapping the structures of the finger and the wrist joint. To the best of our knowledge, it is the first time to achieve photoacoustic imaging of such large human wrist joints. The cross-sectional photoacoustic images of a healthy joint clearly exhibit the main internal structures, including the phalanx, tendons, and blood vessels, which are comparable with the corresponding images by 3.0 T magnetic resonance imaging. The experimental results demonstrate that the proposed system holds promise for early diagnosis of joint disorders. In this study, the feasibility of visualization of human joints using photoacoustic tomography (PAT) is investigated. To verify this idea, the system of integrated optical fiber bundles and a custom-made flexible transducer is established, both of which give the advantage of morphological adaptation; therefore, the coupling section can be worn on human limbs. The imaging capacity of the flexible-transducer-based PAT system is validated by mapping the structures of the finger and the wrist joint. To the best of our knowledge, it is the first time to achieve photoacoustic imaging of such large human wrist joints. The cross-sectional photoacoustic images of a healthy joint clearly exhibit the main internal structures, including the phalanx, tendons, and blood vessels, which are comparable with the corresponding images by 3.0 T magnetic resonance imaging. The experimental results demonstrate that the proposed system holds promise for early diagnosis of joint disorders.
Chinese Optics Letters
- Publication Date: Sep. 10, 2019
- Vol. 17, Issue 9, 091701 (2019)
Spectrophotometer with enhanced sensitivity for uric acid detection
Nurfatihah Che Abd Rashid, Nor Hafizah Ngajikin, Asrul Izam Azmi, Rashidah Arsat, Suhaila Isaak, Noran Azizan Cholan, and Nur Ellina Azmi
A spectrophotometer with an LED as the light source for uric acid detection is proposed in this work. The mechanism of uric acid detection is based on energy absorbed by sodium urate, which is a chemical product of uric acid and sodium hydroxide solution. For the performance validation, comparison between the spectrophotometer with an LED and halogen lamp is carried out. Measurement results suggest that the spectrophotometer system with LED light has better sensitivity than that with halogen light. At a 460 nm wavelength, the sensitivity for the spectrophotometer with an LED is 0.0046 dL/mg, which is 73% higher than that with halogen light that records 0.0012 dL/mg. This enhanced sensitivity is attributed to the higher luminous efficacy of the LED light beam. As a result, a larger amount of flux interacts with the sample, leading to the sensitivity enhancement. The spectrophotometer with an LED is also applied for the detection of uric acid in a real human urine sample. Based on the experimental data at a 460 nm wavelength, the method manages to achieve the sensitivity of 0.0016 dL/mg, accuracy of 96.01%, limit of detection of 4.79 mg/dL, and limit of quantification of 14.52 mg/dL. These findings show that the use of LED as the input light source is promising for the spectrophotometer. A spectrophotometer with an LED as the light source for uric acid detection is proposed in this work. The mechanism of uric acid detection is based on energy absorbed by sodium urate, which is a chemical product of uric acid and sodium hydroxide solution. For the performance validation, comparison between the spectrophotometer with an LED and halogen lamp is carried out. Measurement results suggest that the spectrophotometer system with LED light has better sensitivity than that with halogen light. At a 460 nm wavelength, the sensitivity for the spectrophotometer with an LED is 0.0046 dL/mg, which is 73% higher than that with halogen light that records 0.0012 dL/mg. This enhanced sensitivity is attributed to the higher luminous efficacy of the LED light beam. As a result, a larger amount of flux interacts with the sample, leading to the sensitivity enhancement. The spectrophotometer with an LED is also applied for the detection of uric acid in a real human urine sample. Based on the experimental data at a 460 nm wavelength, the method manages to achieve the sensitivity of 0.0016 dL/mg, accuracy of 96.01%, limit of detection of 4.79 mg/dL, and limit of quantification of 14.52 mg/dL. These findings show that the use of LED as the input light source is promising for the spectrophotometer.
Chinese Optics Letters
- Publication Date: Aug. 10, 2019
- Vol. 17, Issue 8, 081701 (2019)
Tunable protein microlens array|On the Cover
Zhishan Hou, Jiaji Cao, Aiwu Li, and Han Yang
Based on natural protein materials, a series of lenses with different heights and focal lengths were assembled on glass substrates by femtosecond laser non-contact, masking, and cold processing. This lens array itself possesses unique and characteristic optical performance in three-dimensional parallel imaging and bending imaging. What is more profound is that by using equilibrium swelling of protein-hydrogel, once the lens array was placed in a liquid environment, with the change of ion concentration (e.g., pH), the refractive index and curvature of the protein-hydrogel would change, which leads to the flex of the focal plane of the lens, finally realizing the dynamical tunability of a protein microlens. These smart stress devices may have great potential in optical biosensing and microfluidic chip integration fields. Based on natural protein materials, a series of lenses with different heights and focal lengths were assembled on glass substrates by femtosecond laser non-contact, masking, and cold processing. This lens array itself possesses unique and characteristic optical performance in three-dimensional parallel imaging and bending imaging. What is more profound is that by using equilibrium swelling of protein-hydrogel, once the lens array was placed in a liquid environment, with the change of ion concentration (e.g., pH), the refractive index and curvature of the protein-hydrogel would change, which leads to the flex of the focal plane of the lens, finally realizing the dynamical tunability of a protein microlens. These smart stress devices may have great potential in optical biosensing and microfluidic chip integration fields.
Chinese Optics Letters
- Publication Date: Jun. 10, 2019
- Vol. 17, Issue 6, 061702 (2019)
Photothermal biological effects of monomeric erythrocyte using optical tweezers
Hao Lu, Ying Wu, Wenjing Xie, Qi Tang, Caiqin Han, and Ying Liu
The changes of mechanical properties and biological activities of monomeric erythrocytes are studied using optical tweezers micromanipulation technology. Firstly, the mechanical properties of irradiated erythrocyte membranes are obtained. Weaker power laser irradiation can delay the decay of the mechanical properties of erythrocytes and promote the biological activity of erythrocytes, while higher power laser irradiation damages erythrocytes. The stronger the laser irradiation is, the more obvious and rapid the damage will be. The temperature of the cell surface will be changed by regulating the laser power and irradiation time, so the biological functions of erythrocyte can be controlled. Secondly, the finite element simulation of the temperature change on the cell surface under the condition of laser irradiation is carried out using simulation software, and the precise temperature of the cell surface irradiated cumulatively by a laser with different powers is obtained. Finally, the processes of abscission, unfolding, and denaturation of hemoglobins in erythrocytes at different temperatures due to the photothermal effect are analyzed using the model. The mechanism of laser irradiation on the elasticity of erythrocyte membranes is also obtained. The changes of mechanical properties and biological activities of monomeric erythrocytes are studied using optical tweezers micromanipulation technology. Firstly, the mechanical properties of irradiated erythrocyte membranes are obtained. Weaker power laser irradiation can delay the decay of the mechanical properties of erythrocytes and promote the biological activity of erythrocytes, while higher power laser irradiation damages erythrocytes. The stronger the laser irradiation is, the more obvious and rapid the damage will be. The temperature of the cell surface will be changed by regulating the laser power and irradiation time, so the biological functions of erythrocyte can be controlled. Secondly, the finite element simulation of the temperature change on the cell surface under the condition of laser irradiation is carried out using simulation software, and the precise temperature of the cell surface irradiated cumulatively by a laser with different powers is obtained. Finally, the processes of abscission, unfolding, and denaturation of hemoglobins in erythrocytes at different temperatures due to the photothermal effect are analyzed using the model. The mechanism of laser irradiation on the elasticity of erythrocyte membranes is also obtained.
Chinese Optics Letters
- Publication Date: Jun. 10, 2019
- Vol. 17, Issue 6, 061701 (2019)
Improved recognition of Echinococcus granulosus protoscoleces using visual saliency and scale-invariant features
Zhuang Li, Guodong Lü, and Xiaoyi Lü
Echinococcosis—a parasitic disease caused by Echinococcus granulosus or Echinococcus multilocularis larvae—occurs in many regions in the world. This disease can pose a serious threat to public health and thus requires a convenient and cost-effective method for early detection. So, we developed a novel method based on visual saliency and scale-invariant features that detects the tapeworm parasites. This method improves upon existing bottom-up computational saliency models by introducing a visual attention mechanism. The results indicated that the proposed method offers a higher level of both accuracy and computational efficiency when detecting Echinococcus granulosus protoscoleces, which in turn could improve early detection of echinococcosis. Echinococcosis—a parasitic disease caused by Echinococcus granulosus or Echinococcus multilocularis larvae—occurs in many regions in the world. This disease can pose a serious threat to public health and thus requires a convenient and cost-effective method for early detection. So, we developed a novel method based on visual saliency and scale-invariant features that detects the tapeworm parasites. This method improves upon existing bottom-up computational saliency models by introducing a visual attention mechanism. The results indicated that the proposed method offers a higher level of both accuracy and computational efficiency when detecting Echinococcus granulosus protoscoleces, which in turn could improve early detection of echinococcosis.
Chinese Optics Letters
- Publication Date: Apr. 10, 2019
- Vol. 17, Issue 4, 041703 (2019)
Sensing of ultrasonic fields based on polarization parametric indirect microscopic imaging
Yun Cao, Jichuan Xiong, Xuefeng Liu, Zhiying Xia, Weize Wang, N. P. Yadav, and Weiping Liu
This Letter tackles the issue of non-contact detection of ultrasonic fields by utilizing a novel optical method based on the parametric indirect microscopic imaging (PIMI) technique. A general theoretical model describing the three-dimensional anisotropic photoelastic effect in solid was developed. The mechanism of polarization status variations of light passing through the stress and strain fields was analyzed. Non-contact measurements of the ultrasonic field propagating in an isotropic quartz glass have been fulfilled by the PIMI technique under different ultrasonic excitation conditions. PIMI parameters such as sin δ, Φ, and the Stokes parameters have been found to be sensitive to ultrasonic fields. This Letter tackles the issue of non-contact detection of ultrasonic fields by utilizing a novel optical method based on the parametric indirect microscopic imaging (PIMI) technique. A general theoretical model describing the three-dimensional anisotropic photoelastic effect in solid was developed. The mechanism of polarization status variations of light passing through the stress and strain fields was analyzed. Non-contact measurements of the ultrasonic field propagating in an isotropic quartz glass have been fulfilled by the PIMI technique under different ultrasonic excitation conditions. PIMI parameters such as sin δ, Φ, and the Stokes parameters have been found to be sensitive to ultrasonic fields.
Chinese Optics Letters
- Publication Date: Apr. 10, 2019
- Vol. 17, Issue 4, 041702 (2019)
Spectral domain optical coherence tomography with sub-micrometer sensitivity for measurement of central corneal thickness
Lida Zhu, Yi Wang, Yi Yuan, Hongxian Zhou, Yuqian Zhao, and Zhenhe Ma
We demonstrated a method for measurement of central corneal thickness (CCT) with a sub-micrometer sensitivity using a spectral domain optical coherence tomography system without needing a super broad bandwidth light source. By combining the frequency and phase components of Fourier transform, the method is capable of measurement of a large dynamic range with a high sensitivity. Absolute phases are retrieved by comparing the correlations between the detected and simulated interference fringes. The phase unwrapping ability of the present method was quantitatively tested by measuring the displacement of a piezo linear stage. The human CCTs of six volunteers were measured to verify its clinical application. It provides a potential tool for clinical diagnosis and research applications in ophthalmology. We demonstrated a method for measurement of central corneal thickness (CCT) with a sub-micrometer sensitivity using a spectral domain optical coherence tomography system without needing a super broad bandwidth light source. By combining the frequency and phase components of Fourier transform, the method is capable of measurement of a large dynamic range with a high sensitivity. Absolute phases are retrieved by comparing the correlations between the detected and simulated interference fringes. The phase unwrapping ability of the present method was quantitatively tested by measuring the displacement of a piezo linear stage. The human CCTs of six volunteers were measured to verify its clinical application. It provides a potential tool for clinical diagnosis and research applications in ophthalmology.
Chinese Optics Letters
- Publication Date: Apr. 10, 2019
- Vol. 17, Issue 4, 041701 (2019)
Automated segmentation of optical coherence tomography images
C. Kharmyssov, M. W. L. Ko, and J. R. Kim
We propose a fast and accurate automated algorithm to segment retinal pigment epithelium and internal limiting membrane layers from spectral domain optical coherence tomography (SDOCT) B-scan images. A hybrid algorithm, which combines intensity thresholding and graph-based algorithms, was used to process and analyze SDOCT radial scans (120 B scans) images obtained from twenty patients. The relative difference in position of the layers segmented by the proposed hybrid algorithm and by the clinical expert was 1.49% ± 0.01%. The processing time of the hybrid algorithm was 9.3 s for six B scans. Dice’s coefficient of the hybrid algorithm was 96.7% ± 1.6%. The proposed hybrid algorithm for the segmentation of SDOCT images had good agreement with manual segmentation and reduced processing time. We propose a fast and accurate automated algorithm to segment retinal pigment epithelium and internal limiting membrane layers from spectral domain optical coherence tomography (SDOCT) B-scan images. A hybrid algorithm, which combines intensity thresholding and graph-based algorithms, was used to process and analyze SDOCT radial scans (120 B scans) images obtained from twenty patients. The relative difference in position of the layers segmented by the proposed hybrid algorithm and by the clinical expert was 1.49% ± 0.01%. The processing time of the hybrid algorithm was 9.3 s for six B scans. Dice’s coefficient of the hybrid algorithm was 96.7% ± 1.6%. The proposed hybrid algorithm for the segmentation of SDOCT images had good agreement with manual segmentation and reduced processing time.
Chinese Optics Letters
- Publication Date: Jan. 10, 2019
- Vol. 17, Issue 1, 011701 (2019)
3D depth-coded photoacoustic microscopy with a large field of view for human skin imaging
Zhongwen Cheng, Haigang Ma, Zhiyang Wang, and Sihua Yang
Photoacoustic (PA) microscopy comes with high potential for human skin imaging, since it allows noninvasively high-resolution imaging of the natural hemoglobin at depths of several millimeters. Here, we developed a PA microscopy to achieve high-resolution, high-contrast, and large field of view imaging of skin. A three-dimensional (3D) depth-coding technology was used to encode the depth information in PA images, which is very intuitive for identifying the depth of blood vessels in a two-dimensional image, and the vascular structure can be analyzed at different depths. Imaging results demonstrate that the 3D depth-coded PA microscopy should be translated from the bench to the bedside. Photoacoustic (PA) microscopy comes with high potential for human skin imaging, since it allows noninvasively high-resolution imaging of the natural hemoglobin at depths of several millimeters. Here, we developed a PA microscopy to achieve high-resolution, high-contrast, and large field of view imaging of skin. A three-dimensional (3D) depth-coding technology was used to encode the depth information in PA images, which is very intuitive for identifying the depth of blood vessels in a two-dimensional image, and the vascular structure can be analyzed at different depths. Imaging results demonstrate that the 3D depth-coded PA microscopy should be translated from the bench to the bedside.
Chinese Optics Letters
- Publication Date: Aug. 10, 2018
- Vol. 16, Issue 8, 081701 (2018)
Simultaneous blood flow and oxygenation measurements using an off-the-shelf spectrometer
Myeongsu Seong, Phuong Minh Mai, Kijoon Lee, and Jae Gwan Kim
Blood oxygenation and flow are both important parameters in a living body. In this Letter, we introduce a simple configuration to simultaneously measure blood flow and oxygenation using an off-the-shelf spectrometer. With the integration time of 10 ms, flow phantom measurements, a liquid blood phantom test, and an arm cuff occlusion paradigm were performed to validate the feasibility of the system. We expect this proof-of-concept study would be widely adopted by other researchers for acquiring both blood flow and oxygenation changes due to its straightforward configuration and the possibility of multimodal measurement. Blood oxygenation and flow are both important parameters in a living body. In this Letter, we introduce a simple configuration to simultaneously measure blood flow and oxygenation using an off-the-shelf spectrometer. With the integration time of 10 ms, flow phantom measurements, a liquid blood phantom test, and an arm cuff occlusion paradigm were performed to validate the feasibility of the system. We expect this proof-of-concept study would be widely adopted by other researchers for acquiring both blood flow and oxygenation changes due to its straightforward configuration and the possibility of multimodal measurement.
Chinese Optics Letters
- Publication Date: Jul. 10, 2018
- Vol. 16, Issue 7, 071701 (2018)
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