Pub Date : 2025-09-05DOI: 10.1016/j.pacs.2025.100767
Wenzhe Wang , Zhiyu Feng , Yachao Jiang , Jie Zhang , Shiyu Yan , Xiaohong Cao , Ping Lu , Chaotan Sima
A topological optimization method for photoacoustic resonators is proposed as the Method of Moving Asymptotes with Bernstein Polynomials (MMA-BP). This method is demonstrated in a ppt-level ultra-sensitive photoacoustic spectroscopy gas sensor using miniaturized vase-type photoacoustic cell (V-PAC). The V-PAC has a volume of merely 5 mL and achieves a minimum detection limit of 281 ppt for C2H2 with an integration time of 768 s, corresponding to a normalized noise equivalent absorption of 4.46 × 10⁻9∙cm⁻1∙Hz⁻1/2 with a single optical path. It represents an improvement of approximately 14 times beyond that of using the conventional T-type PAC. We experimentally investigated consequent frequency shifts within conventional PACs with thin resonator tubes, and determined the influence of losses on the resonant frequency shift. The geometric contraction effect in vase-type PAC is also investigated. The proposed topological MMA-BP method and implementations provide a universal approach to establish optimized PAC structures for photoacoustic gas detection.
{"title":"Topological optimization method “MMA-BP” for photoacoustic resonator and implementations in ppt-level gas sensor using miniaturized vase-type photoacoustic cells","authors":"Wenzhe Wang , Zhiyu Feng , Yachao Jiang , Jie Zhang , Shiyu Yan , Xiaohong Cao , Ping Lu , Chaotan Sima","doi":"10.1016/j.pacs.2025.100767","DOIUrl":"10.1016/j.pacs.2025.100767","url":null,"abstract":"<div><div>A topological optimization method for photoacoustic resonators is proposed as the Method of Moving Asymptotes with Bernstein Polynomials (MMA-BP). This method is demonstrated in a ppt-level ultra-sensitive photoacoustic spectroscopy gas sensor using miniaturized vase-type photoacoustic cell (V-PAC). The V-PAC has a volume of merely 5 mL and achieves a minimum detection limit of 281 ppt for C<sub>2</sub>H<sub>2</sub> with an integration time of 768 s, corresponding to a normalized noise equivalent absorption of 4.46 × 10⁻<sup>9</sup>∙cm⁻<sup>1</sup>∙Hz⁻<sup>1/2</sup> with a single optical path. It represents an improvement of approximately 14 times beyond that of using the conventional T-type PAC. We experimentally investigated consequent frequency shifts within conventional PACs with thin resonator tubes, and determined the influence of losses on the resonant frequency shift. The geometric contraction effect in vase-type PAC is also investigated. The proposed topological MMA-BP method and implementations provide a universal approach to establish optimized PAC structures for photoacoustic gas detection.</div></div>","PeriodicalId":56025,"journal":{"name":"Photoacoustics","volume":"46 ","pages":"Article 100767"},"PeriodicalIF":6.8,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145010867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-22DOI: 10.1016/j.pacs.2025.100763
Cayla A. Wood , Claire E. Jones , Ananthakrishnan Soundaram Jeevarathinam, Riley Watson, Sangheon Han, Jennifer Meyer, Konstantin V. Sokolov, Richard R. Bouchard
Liposomal carriers, used for site-specific drug delivery, are being investigated for diagnostic approaches by replacing the therapeutic with an imaging contrast agent, exploring potential for selective treatment planning. There remains a critical need to improve in vivo assessment of biodistribution, stability, and clearance kinetics of liposomal carriers. This pilot study presents a multimodal approach in which liposome-encapsulated J-aggregated indocyanine green (ICG) dye (Lipo-JICG) is imaged with high spatial resolution using both in vivo photoacoustic (PA) imaging, to assess the absorbance characteristics of JICG and monomeric ICG, and ex vivo cryofluorescence tomography (CFT), to measure ICG fluorescence. An in vitro assay comparing the relationship between absorbance and fluorescence of Lipo-JICG and ICG demonstrated that the absorbance peak shifted from 780 to 895 nm as the Lipo-JICG:ICG ratio increased; meanwhile, the fluorescence decreased drastically as the Lipo-JICG:ICG ratio increased, demonstrating that J-aggregation quenches fluorescence. Twelve mice were then PA imaged pre-injection, then up to 6 days after Lipo-JICG injection. Unmixed Lipo-JICG signal peaked at 30 min post-injection in both liver and spleen; unmixed ICG signal peaked post-injection, decreasing over time in both organs and increasing at 6 days in the spleen. With CFT, ICG fluorescence followed a similar trend, with a maximum at 30 min in liver and at 6 days in spleen, implying that Lipo-JICG continued to break down and excrete through the hepatic system over 6 days post-injection. Future studies will continue to develop this methodology to assess biodistribution, stability, and clearance of liposomal carriers in tumor-bearing murine models.
{"title":"A multimodal approach to assess a liposomal carrier’s biodistribution, stability, and clearance","authors":"Cayla A. Wood , Claire E. Jones , Ananthakrishnan Soundaram Jeevarathinam, Riley Watson, Sangheon Han, Jennifer Meyer, Konstantin V. Sokolov, Richard R. Bouchard","doi":"10.1016/j.pacs.2025.100763","DOIUrl":"10.1016/j.pacs.2025.100763","url":null,"abstract":"<div><div>Liposomal carriers, used for site-specific drug delivery, are being investigated for diagnostic approaches by replacing the therapeutic with an imaging contrast agent, exploring potential for selective treatment planning. There remains a critical need to improve <em>in vivo</em> assessment of biodistribution, stability, and clearance kinetics of liposomal carriers. This pilot study presents a multimodal approach in which liposome-encapsulated J-aggregated indocyanine green (ICG) dye (Lipo-JICG) is imaged with high spatial resolution using both <em>in vivo</em> photoacoustic (PA) imaging, to assess the absorbance characteristics of JICG and monomeric ICG, and <em>ex vivo</em> cryofluorescence tomography (CFT), to measure ICG fluorescence. An <em>in vitro</em> assay comparing the relationship between absorbance and fluorescence of Lipo-JICG and ICG demonstrated that the absorbance peak shifted from 780 to 895 nm as the Lipo-JICG:ICG ratio increased; meanwhile, the fluorescence decreased drastically as the Lipo-JICG:ICG ratio increased, demonstrating that J-aggregation quenches fluorescence. Twelve mice were then PA imaged pre-injection, then up to 6 days after Lipo-JICG injection. Unmixed Lipo-JICG signal peaked at 30 min post-injection in both liver and spleen; unmixed ICG signal peaked post-injection, decreasing over time in both organs and increasing at 6 days in the spleen. With CFT, ICG fluorescence followed a similar trend, with a maximum at 30 min in liver and at 6 days in spleen, implying that Lipo-JICG continued to break down and excrete through the hepatic system over 6 days post-injection. Future studies will continue to develop this methodology to assess biodistribution, stability, and clearance of liposomal carriers in tumor-bearing murine models.</div></div>","PeriodicalId":56025,"journal":{"name":"Photoacoustics","volume":"46 ","pages":"Article 100763"},"PeriodicalIF":6.8,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144912183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-21DOI: 10.1016/j.pacs.2025.100761
Zhuoying Wang, Ziang Feng, Song Hu
Photoacoustic microscopy (PAM) enables label-free, quantitative imaging of blood flow and oxygenation in vivo, offering critical insights into microvascular function and tissue metabolism. However, current flow quantification methods suffer from poor accuracy at extreme flow speeds and high computational costs. We present Hybrid Fourier-Derivative Analysis (HFDA), a new method based on frequency analysis of flow-induced modulations in photoacoustic amplitude. Compatible with standard raster scanning, HFDA adaptively integrates Fourier analysis for high-speed flow and derivative analysis for low-speed flow, achieving high accuracy and computational efficiency. Phantom studies validate the accuracy of HFDA across 0.2–20 mm/s, with errors typically less than 7 %. Compared to correlation-based methods, HFDA reduces computational time by 35-fold. In vivo demonstrations in mouse models of hypoxia and hypercapnia further underscore the potential of HFDA as a rapid and precise tool for blood flow quantification in functional and metabolic PAM studies.
{"title":"Hybrid Fourier-Derivative Analysis: An accurate and fast method for blood flow quantification in photoacoustic microscopy","authors":"Zhuoying Wang, Ziang Feng, Song Hu","doi":"10.1016/j.pacs.2025.100761","DOIUrl":"10.1016/j.pacs.2025.100761","url":null,"abstract":"<div><div>Photoacoustic microscopy (PAM) enables label-free, quantitative imaging of blood flow and oxygenation <em>in vivo</em>, offering critical insights into microvascular function and tissue metabolism. However, current flow quantification methods suffer from poor accuracy at extreme flow speeds and high computational costs. We present Hybrid Fourier-Derivative Analysis (HFDA), a new method based on frequency analysis of flow-induced modulations in photoacoustic amplitude. Compatible with standard raster scanning, HFDA adaptively integrates Fourier analysis for high-speed flow and derivative analysis for low-speed flow, achieving high accuracy and computational efficiency. Phantom studies validate the accuracy of HFDA across 0.2–20 mm/s, with errors typically less than 7 %. Compared to correlation-based methods, HFDA reduces computational time by 35-fold. <em>In vivo</em> demonstrations in mouse models of hypoxia and hypercapnia further underscore the potential of HFDA as a rapid and precise tool for blood flow quantification in functional and metabolic PAM studies.</div></div>","PeriodicalId":56025,"journal":{"name":"Photoacoustics","volume":"46 ","pages":"Article 100761"},"PeriodicalIF":6.8,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145010868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study evaluates the efficacy of photoacoustic/ultrasound (PA/US) imaging-based radiomics for distinguishing HER2-zero, HER2-low, and HER2-positive breast cancer (BC), aiming to enhance targeted therapy selection.
Methods
We analyzed 346 pathologically confirmed BC patients who underwent multimodal PA/US imaging at Shenzhen People’s Hospital from January 2022 to January 2025. HER2 status was determined pathologically and classified into three levels. Radiologists assessed conventional US features and manually segmented tumors on PA-images for radiomics feature extraction. Using the Least Absolute Shrinkage and Selection Operator analysis, we developed radiomics models for differentiating between HER2-zero versus HER2-low/positive cancers (Task 1), and HER2-low versus positive cancers (Task 2), and HER2-zero versus low cancers (Task 3). Patients were randomly divided into training sets and testing sets. Multivariate logistic regression was used to integrate radiomics, clinical-pathological, and US features into nomograms.
Results
In testing set, radiomics features demonstrated an AUC of 0.846 with sensitivity of 79.3 % and specificity of 72.7 % for Task 1, and an AUC of 0.801 with sensitivity of 64.0 % and specificity of 82.8 % for Task 2, and an AUC of 0.767 with sensitivity of 80.7 % and specificity of 72.7 % for Task 3. For Task 1, 2 and 3, nomograms including PA imaging radiomics features combined with clinical-pathological features achieved AUCs of 0.848, 0.881 and 0.780, respectively.
Conclusion
PA radiomics features effectively differentiate between HER2-zero and HER2 low/positive, and between HER2-low and HER2-positive BC, offering potential utility in guiding targeted therapy decisions.
Summary
This study demonstrates the potential of PA imaging-based radiomics for accurately classifying HER2 expression statuses in BC, enhancing the selection process for targeted therapies. By integrating multi-modal imaging and pathology data, the developed radiomics models show robust performance, promising a non-invasive diagnostic supplementary for clinical application where traditional methods are limited.
{"title":"Multimodal PA/US imaging and radiomics for the prediction of HER2-zero, -low, and -positive breast cancers: A novel approach for targeted therapy selection","authors":"Zhibin Huang , Guoqiu Li , Mengyun Wang , Sijie Mo, Huaiyu Wu, Hongtian Tian, Shuzhen Tang, Jinfeng Xu, Fajin Dong","doi":"10.1016/j.pacs.2025.100764","DOIUrl":"10.1016/j.pacs.2025.100764","url":null,"abstract":"<div><h3>Purpose</h3><div>This study evaluates the efficacy of photoacoustic/ultrasound (PA/US) imaging-based radiomics for distinguishing HER2-zero, HER2-low, and HER2-positive breast cancer (BC), aiming to enhance targeted therapy selection.</div></div><div><h3>Methods</h3><div>We analyzed 346 pathologically confirmed BC patients who underwent multimodal PA/US imaging at Shenzhen People’s Hospital from January 2022 to January 2025. HER2 status was determined pathologically and classified into three levels. Radiologists assessed conventional US features and manually segmented tumors on PA-images for radiomics feature extraction. Using the Least Absolute Shrinkage and Selection Operator analysis, we developed radiomics models for differentiating between HER2-zero versus HER2-low/positive cancers (Task 1), and HER2-low versus positive cancers (Task 2), and HER2-zero versus low cancers (Task 3). Patients were randomly divided into training sets and testing sets. Multivariate logistic regression was used to integrate radiomics, clinical-pathological, and US features into nomograms.</div></div><div><h3>Results</h3><div>In testing set, radiomics features demonstrated an AUC of 0.846 with sensitivity of 79.3 % and specificity of 72.7 % for Task 1, and an AUC of 0.801 with sensitivity of 64.0 % and specificity of 82.8 % for Task 2, and an AUC of 0.767 with sensitivity of 80.7 % and specificity of 72.7 % for Task 3. For Task 1, 2 and 3, nomograms including PA imaging radiomics features combined with clinical-pathological features achieved AUCs of 0.848, 0.881 and 0.780, respectively.</div></div><div><h3>Conclusion</h3><div>PA radiomics features effectively differentiate between HER2-zero and HER2 low/positive, and between HER2-low and HER2-positive BC, offering potential utility in guiding targeted therapy decisions.</div></div><div><h3>Summary</h3><div>This study demonstrates the potential of PA imaging-based radiomics for accurately classifying HER2 expression statuses in BC, enhancing the selection process for targeted therapies. By integrating multi-modal imaging and pathology data, the developed radiomics models show robust performance, promising a non-invasive diagnostic supplementary for clinical application where traditional methods are limited.</div></div>","PeriodicalId":56025,"journal":{"name":"Photoacoustics","volume":"46 ","pages":"Article 100764"},"PeriodicalIF":6.8,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144933471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-19DOI: 10.1016/j.pacs.2025.100762
Chuanwen Qian , Wenjun Ni , Chunyong Yang , Zhongke Zhao , Likang Zhang , Sixiang Ran , Chenyu Wang , Ping Lu , Perry Ping Shum
A novel gourd-type photoacoustic cell (GTPAC) has been developed, featuring a highly reflective, polished gold film-coated inner wall that minimizes optical loss and maximizes light utilization efficiency. GTPAC integrates two coupled spherical chambers with a radius ratio 2:3, which is close to the golden ratio. Its unique Gaussian curvature distribution enables multi-directional, disordered light beam reflection without complex optical alignment. It creates a non-periodic three-dimensional (3D) optical trajectory, significantly enhancing light-molecule interactions. GTPAC achieves an exceptionally high sensitivity of up to 3.36 μV/ppm using a distributed feedback butterfly laser with central wavelength of 1532 nm (±1.5 nm) to detect acetylene gas. When the integration time is extended to 100 s, the minimum detection limit is as low as 0.59 ppb. Moreover, its flexible design and broad spectral compatibility enable significant potential for extension to other gases, such as methane and nitrogen oxides, offering new prospects for ultra-sensitive trace gas detection.
{"title":"Three-dimensional optical path extended gourd-type photoacoustic cell for highly sensitive trace acetylene sensing","authors":"Chuanwen Qian , Wenjun Ni , Chunyong Yang , Zhongke Zhao , Likang Zhang , Sixiang Ran , Chenyu Wang , Ping Lu , Perry Ping Shum","doi":"10.1016/j.pacs.2025.100762","DOIUrl":"10.1016/j.pacs.2025.100762","url":null,"abstract":"<div><div>A novel gourd-type photoacoustic cell (GTPAC) has been developed, featuring a highly reflective, polished gold film-coated inner wall that minimizes optical loss and maximizes light utilization efficiency. GTPAC integrates two coupled spherical chambers with a radius ratio 2:3, which is close to the golden ratio. Its unique Gaussian curvature distribution enables multi-directional, disordered light beam reflection without complex optical alignment. It creates a non-periodic three-dimensional (3D) optical trajectory, significantly enhancing light-molecule interactions. GTPAC achieves an exceptionally high sensitivity of up to 3.36 μV/ppm using a distributed feedback butterfly laser with central wavelength of 1532 nm (±1.5 nm) to detect acetylene gas. When the integration time is extended to 100 s, the minimum detection limit is as low as 0.59 ppb. Moreover, its flexible design and broad spectral compatibility enable significant potential for extension to other gases, such as methane and nitrogen oxides, offering new prospects for ultra-sensitive trace gas detection.</div></div>","PeriodicalId":56025,"journal":{"name":"Photoacoustics","volume":"45 ","pages":"Article 100762"},"PeriodicalIF":6.8,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144886799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-13DOI: 10.1016/j.pacs.2025.100760
Xiaowei Chen , Xue Wen , Bingyan Fang , Zhixiong Lei , Jiarui Chen , Lvming Zeng , Kedi Xiong , Weizhan Luo , Lan Zhang , Hongbo Fu , Shiyue Li , Jian Zhang
Integrated photoacoustic endoscopy and endoscopic ultrasound (PAE/EUS) are recognized as an effective method for detecting intestinal and intravascular diseases. Changes in the morphology and composition of the trachea are significant hallmarks of respiratory diseases. In this study, an acoustic-optic confocal probe was developed and integrated at the tip of a 2.1 mm diameter catheter to perform simultaneous PAE/EUS imaging. Phantom experimental results demonstrated that the catheter achieved a high lateral resolution of 11 µm, with an imaging depth of 12 mm, using an excitation energy of 1.5 μJ. Trachea from healthy and chronic obstructive pulmonary disease (COPD) rabbit models and in vivo were imaged by the PAE/EUS system. The results demonstrated that photoacoustic imaging could identify increases in the diameter and density of the tracheal microvessels, while ultrasound imaging provided detailed views of the tracheal submucosa. These findings underscore the potential of PAE/EUS in the diagnosis of COPD.
{"title":"An acoustic-optic confocal probe based photoacoustic and ultrasonic tracheal endoscopy for characterizing phantom and model of chronic obstructive pulmonary disease","authors":"Xiaowei Chen , Xue Wen , Bingyan Fang , Zhixiong Lei , Jiarui Chen , Lvming Zeng , Kedi Xiong , Weizhan Luo , Lan Zhang , Hongbo Fu , Shiyue Li , Jian Zhang","doi":"10.1016/j.pacs.2025.100760","DOIUrl":"10.1016/j.pacs.2025.100760","url":null,"abstract":"<div><div>Integrated photoacoustic endoscopy and endoscopic ultrasound (PAE/EUS) are recognized as an effective method for detecting intestinal and intravascular diseases. Changes in the morphology and composition of the trachea are significant hallmarks of respiratory diseases. In this study, an acoustic-optic confocal probe was developed and integrated at the tip of a 2.1 mm diameter catheter to perform simultaneous PAE/EUS imaging. Phantom experimental results demonstrated that the catheter achieved a high lateral resolution of 11 µm, with an imaging depth of 12 mm, using an excitation energy of 1.5 μJ. Trachea from healthy and chronic obstructive pulmonary disease (COPD) rabbit models and <em>in vivo</em> were imaged by the PAE/EUS system. The results demonstrated that photoacoustic imaging could identify increases in the diameter and density of the tracheal microvessels, while ultrasound imaging provided detailed views of the tracheal submucosa. These findings underscore the potential of PAE/EUS in the diagnosis of COPD.</div></div>","PeriodicalId":56025,"journal":{"name":"Photoacoustics","volume":"45 ","pages":"Article 100760"},"PeriodicalIF":6.8,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144852379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-10DOI: 10.1016/j.pacs.2025.100759
Zhenfeng Gong , Ruoran Kan , Mingzhe Li , Mi Zhou , Guojie Wu , Xiang Chen
This paper investigates the light-induced thermoelastic spectroscopy (LITES) based on transmitted light amplification to realize high-precision gas detection. The modulated laser beam passes through a multi-pass cell and is then coupled to an optical amplifier. The multi-pass cell reflects the laser beam 100 times, has an optical length of 16 m, and its transmitted light intensity is 1.67 mW. A narrowband fiber optical filter with a bandwidth of 0.8 nm is utilized to suppress optical noise. Based on the transmitted light amplification, the signal-to-noise ratio (SNR) is improved by a factor of 3.6. To investigate the enhancement of second harmonic (2 f) signals under weak light intensities, a fiber optical attenuator is adopted to attenuate the transmitted light intensity. While the transmitted light intensity is attenuated to 0.048 mW, a high SNR of 1823 and a minimum detection limit (MDL) of 0.110 ppm can be obtained. Hence, LITES based on transmitted light amplification enables high-precision measurements while the light intensity is only at the scale of μW. This approach facilitates a significant increase in the number of beam reflections as well as the optical length of the multi-pass cell and resonant cavity for LITES sensors.
{"title":"Sensitive light-induced thermoelastic spectroscopy based on transmitted light amplification","authors":"Zhenfeng Gong , Ruoran Kan , Mingzhe Li , Mi Zhou , Guojie Wu , Xiang Chen","doi":"10.1016/j.pacs.2025.100759","DOIUrl":"10.1016/j.pacs.2025.100759","url":null,"abstract":"<div><div>This paper investigates the light-induced thermoelastic spectroscopy (LITES) based on transmitted light amplification to realize high-precision gas detection. The modulated laser beam passes through a multi-pass cell and is then coupled to an optical amplifier. The multi-pass cell reflects the laser beam 100 times, has an optical length of 16 m, and its transmitted light intensity is 1.67 mW. A narrowband fiber optical filter with a bandwidth of 0.8 nm is utilized to suppress optical noise. Based on the transmitted light amplification, the signal-to-noise ratio (SNR) is improved by a factor of 3.6. To investigate the enhancement of second harmonic (2 <em>f</em>) signals under weak light intensities, a fiber optical attenuator is adopted to attenuate the transmitted light intensity. While the transmitted light intensity is attenuated to 0.048 mW, a high SNR of 1823 and a minimum detection limit (MDL) of 0.110 ppm can be obtained. Hence, LITES based on transmitted light amplification enables high-precision measurements while the light intensity is only at the scale of μW. This approach facilitates a significant increase in the number of beam reflections as well as the optical length of the multi-pass cell and resonant cavity for LITES sensors.</div></div>","PeriodicalId":56025,"journal":{"name":"Photoacoustics","volume":"45 ","pages":"Article 100759"},"PeriodicalIF":6.8,"publicationDate":"2025-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-06DOI: 10.1016/j.pacs.2025.100757
Junjie She , Qican Zhang , Yajun Wang , Hongying Hu , Meng You , Junfei Shen
Photoacoustic microscopy (PAM) offers high-resolution, non-invasive, and label-free imaging, making it invaluable for biomedical research. However, slow data acquisition and high sampling requirements remain key challenges that limit its broader applicability and scalability. We propose an Information-Efficient Photoacoustic Microscopy (IE-PAM) that jointly integrates sparse scanning encoding with neural network decoding to achieve high-quality reconstruction from extremely limited measurements. Specifically, IE-PAM employs a sparse-scanning acquisition scheme guided by random binary masks and reconstructs high-fidelity images using AFDU-Net, a custom-designed neural decoder trained on fully sampled ground truth data. Our system can faithfully recover detailed anatomical structures from as little as 1.5 % of the full sampling rate, corresponding to more than a 66-fold increase in acquisition efficiency. In in-vivo experiments on mouse ear vasculature, IE-PAM outperforms both traditional and learning-based baselines in fine vascular fidelity, artifact suppression, and robustness across varying sampling rates. By minimizing information redundancy at the acquisition stage and enabling accurate reconstruction from minimal data, IE-PAM provides a foundation for efficient, fast and scalable photoacoustic imaging in both preclinical and research applications.
{"title":"Sparse scanning encoding and neural network decoding for compressed photoacoustic microscopy","authors":"Junjie She , Qican Zhang , Yajun Wang , Hongying Hu , Meng You , Junfei Shen","doi":"10.1016/j.pacs.2025.100757","DOIUrl":"10.1016/j.pacs.2025.100757","url":null,"abstract":"<div><div>Photoacoustic microscopy (PAM) offers high-resolution, non-invasive, and label-free imaging, making it invaluable for biomedical research. However, slow data acquisition and high sampling requirements remain key challenges that limit its broader applicability and scalability. We propose an Information-Efficient Photoacoustic Microscopy (IE-PAM) that jointly integrates sparse scanning encoding with neural network decoding to achieve high-quality reconstruction from extremely limited measurements. Specifically, IE-PAM employs a sparse-scanning acquisition scheme guided by random binary masks and reconstructs high-fidelity images using AFDU-Net, a custom-designed neural decoder trained on fully sampled ground truth data. Our system can faithfully recover detailed anatomical structures from as little as 1.5 % of the full sampling rate, corresponding to more than a 66-fold increase in acquisition efficiency. In in-vivo experiments on mouse ear vasculature, IE-PAM outperforms both traditional and learning-based baselines in fine vascular fidelity, artifact suppression, and robustness across varying sampling rates. By minimizing information redundancy at the acquisition stage and enabling accurate reconstruction from minimal data, IE-PAM provides a foundation for efficient, fast and scalable photoacoustic imaging in both preclinical and research applications.</div></div>","PeriodicalId":56025,"journal":{"name":"Photoacoustics","volume":"45 ","pages":"Article 100757"},"PeriodicalIF":6.8,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-06DOI: 10.1016/j.pacs.2025.100758
Chen Zhang , Yan Gao , Ruyue Cui , Hanxi Zhang , Jinhua Tian , Yujie Tang , Lei Yang , Chaofan Feng , Pietro Patimisco , Angelo Sampaolo , Vincenzo Spagnolo , Xukun Yin , Lei Dong , Hongpeng Wu
We present a novel approach for gas concentration measurement using a differential resonant photoacoustic cell combined with a deep learning-based signal denoising model. This method addresses the persistent challenge of noise interference in 2 f signals at low gas concentrations, where conventional processing methods struggle to maintain signal fidelity. To resolve this, we propose a deep learning model that integrates 1D Convolutional Neural Networks (1D CNNs) for local feature extraction and Transformer networks for capturing global dependencies. The model was trained using synthetic signals with added noise to simulate real-world conditions, ensuring robustness and adaptability. Applied to experimental 2 f signals, the model demonstrated excellent noise suppression capabilities, enhancing the signal-to-noise ratio (SNR) of 500 ppb acetylene signals by a factor of approximately 70. Furthermore, the determination coefficient (R²) improved, reflecting better accuracy and linearity in signal reconstruction. These results underscore the model's potential for improving detection sensitivity and reliability in trace gas measurements, marking a significant advancement in spectroscopic signal processing for gas detection.
{"title":"Enhancing photoacoustic trace gas detection via a CNN–transformer denoising framework","authors":"Chen Zhang , Yan Gao , Ruyue Cui , Hanxi Zhang , Jinhua Tian , Yujie Tang , Lei Yang , Chaofan Feng , Pietro Patimisco , Angelo Sampaolo , Vincenzo Spagnolo , Xukun Yin , Lei Dong , Hongpeng Wu","doi":"10.1016/j.pacs.2025.100758","DOIUrl":"10.1016/j.pacs.2025.100758","url":null,"abstract":"<div><div>We present a novel approach for gas concentration measurement using a differential resonant photoacoustic cell combined with a deep learning-based signal denoising model. This method addresses the persistent challenge of noise interference in 2 <em>f</em> signals at low gas concentrations, where conventional processing methods struggle to maintain signal fidelity. To resolve this, we propose a deep learning model that integrates 1D Convolutional Neural Networks (1D CNNs) for local feature extraction and Transformer networks for capturing global dependencies. The model was trained using synthetic signals with added noise to simulate real-world conditions, ensuring robustness and adaptability. Applied to experimental 2 <em>f</em> signals, the model demonstrated excellent noise suppression capabilities, enhancing the signal-to-noise ratio (SNR) of 500 ppb acetylene signals by a factor of approximately 70. Furthermore, the determination coefficient (R²) improved, reflecting better accuracy and linearity in signal reconstruction. These results underscore the model's potential for improving detection sensitivity and reliability in trace gas measurements, marking a significant advancement in spectroscopic signal processing for gas detection.</div></div>","PeriodicalId":56025,"journal":{"name":"Photoacoustics","volume":"45 ","pages":"Article 100758"},"PeriodicalIF":6.8,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144810598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-05DOI: 10.1016/j.pacs.2025.100755
Songqing Xie , Zhuojun Xie , Shuai Na
Electrical conductivity is a critical biomarker for cellular activity and a fundamental parameter in material science. However, achieving label-free, contact-free conductivity measurements with optical-scale resolution remains a challenge. Here, we introduce a magneto-photoacoustic coupling effect that enables conductivity mapping through photoacoustic excitation in the presence of a static magnetic field. The governing equation for this phenomenon is derived, demonstrating a linear relationship between the induced photoacoustic pressure and the product of the local magnetic flux density squared and electrical conductivity. This theoretical framework is further validated using numerical simulation, which showcases the method’s capability for optical-resolution conductivity imaging. The proposed approach unlocks new opportunities for applications ranging from real-time tracking of neuronal ion channel dynamics to nanoscale defect characterization in metallic and semiconductor materials.
{"title":"Magneto-photoacoustic coupling: A pathway to optical-resolution electrical conductivity imaging","authors":"Songqing Xie , Zhuojun Xie , Shuai Na","doi":"10.1016/j.pacs.2025.100755","DOIUrl":"10.1016/j.pacs.2025.100755","url":null,"abstract":"<div><div>Electrical conductivity is a critical biomarker for cellular activity and a fundamental parameter in material science. However, achieving label-free, contact-free conductivity measurements with optical-scale resolution remains a challenge. Here, we introduce a magneto-photoacoustic coupling effect that enables conductivity mapping through photoacoustic excitation in the presence of a static magnetic field. The governing equation for this phenomenon is derived, demonstrating a linear relationship between the induced photoacoustic pressure and the product of the local magnetic flux density squared and electrical conductivity. This theoretical framework is further validated using numerical simulation, which showcases the method’s capability for optical-resolution conductivity imaging. The proposed approach unlocks new opportunities for applications ranging from real-time tracking of neuronal ion channel dynamics to nanoscale defect characterization in metallic and semiconductor materials.</div></div>","PeriodicalId":56025,"journal":{"name":"Photoacoustics","volume":"45 ","pages":"Article 100755"},"PeriodicalIF":6.8,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144780935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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