GV
G.V. Vdovine
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65 records found
1
Journal article
(2026)
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Wenjun Chen, Xiaoping Li, Herman Koara, Gleb Vdovin, Weimin Bao, Zhongwen Deng, Chenxu Wang, Shuwei Zhang, Haifeng Sun, Hengkang Zhang, Lin Li, Li Wang, Hai Gong
Space-based distributed array telescope formations hold substantial potential for deep space exploration, with their performance highly dependent on precise baseline measurements between subtelescopes. This study presents a double-sideband frequency-sweeping interferometry (DSB-FSI) technique based on electro-optic modulation for intertelescope baseline measurements. To address the lack of on-orbit frequency-sweep calibration references, a Fabry–Pérot etalon is used for real-time in situ frequency-sweep rate calibration. Experimental results show that the Fabry–Pérot etalon effectively calibrates the frequency-sweep rate of the DSB-FSI system, reducing long-term baseline measurement drift error from 20.11 to 13.38 μm and decreasing maximum measurement deviation from 18.03 to 13.14 μm over a 5.7-m baseline. Metrological calibration confirms that the calibrated system achieves a baseline measurement accuracy of 44.30 μm over a 10-m range, with excellent dynamic measurement performance for monitoring baseline variations. The DSB-FSI technique is expected to provide a reliable solution for the high-precision intertelescope baseline measurements in “MEAYIN” (Multiple-Spacecraft Exoplanet Aperture Synthetic Interferometer) project, thus supporting the advancement of space-based distributed array telescope formation technologies.
...
Space-based distributed array telescope formations hold substantial potential for deep space exploration, with their performance highly dependent on precise baseline measurements between subtelescopes. This study presents a double-sideband frequency-sweeping interferometry (DSB-FSI) technique based on electro-optic modulation for intertelescope baseline measurements. To address the lack of on-orbit frequency-sweep calibration references, a Fabry–Pérot etalon is used for real-time in situ frequency-sweep rate calibration. Experimental results show that the Fabry–Pérot etalon effectively calibrates the frequency-sweep rate of the DSB-FSI system, reducing long-term baseline measurement drift error from 20.11 to 13.38 μm and decreasing maximum measurement deviation from 18.03 to 13.14 μm over a 5.7-m baseline. Metrological calibration confirms that the calibrated system achieves a baseline measurement accuracy of 44.30 μm over a 10-m range, with excellent dynamic measurement performance for monitoring baseline variations. The DSB-FSI technique is expected to provide a reliable solution for the high-precision intertelescope baseline measurements in “MEAYIN” (Multiple-Spacecraft Exoplanet Aperture Synthetic Interferometer) project, thus supporting the advancement of space-based distributed array telescope formation technologies.
Journal article
(2026)
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Zhongwen Deng, Wenjun Chen, Xiawei Meng, Xin Yao, Lin Li, Hengkang Zhang, Hai Gong, Xiaoping Li, Gleb Vdovin, More Authors
Frequency-scanning nonlinearity fundamentally limits the ranging precision of frequency-scanning interferometry (FSI) systems based on external cavity diode lasers (ECDLs). To address this limitation, a frequency scanning nonlinearity suppression method based on a rate-dependent asymmetric Prandtl–Ishlinskii (RA-PI) model is proposed. By employing, for the first time, a phenomenological modeling approach, the rate-dependent and asymmetric nonlinear optical frequency response of the ECDL is accurately characterized. An inverse RA-PI model is derived and implemented as a feedforward compensator to linearize the frequency scanning. Experimental results show that the frequency-scanning linearity is improved by approximately one order of magnitude. Consequently, the maximum standard deviation of absolute distance measurements is reduced from 58.25 µm to 9.79 µm, and the maximum relative displacement deviation decreases from 42.97 µm to 11.56 µm. Furthermore, the velocity measurement precision for dynamic targets is improved by a factor of 2.61 to 5.75.
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Frequency-scanning nonlinearity fundamentally limits the ranging precision of frequency-scanning interferometry (FSI) systems based on external cavity diode lasers (ECDLs). To address this limitation, a frequency scanning nonlinearity suppression method based on a rate-dependent asymmetric Prandtl–Ishlinskii (RA-PI) model is proposed. By employing, for the first time, a phenomenological modeling approach, the rate-dependent and asymmetric nonlinear optical frequency response of the ECDL is accurately characterized. An inverse RA-PI model is derived and implemented as a feedforward compensator to linearize the frequency scanning. Experimental results show that the frequency-scanning linearity is improved by approximately one order of magnitude. Consequently, the maximum standard deviation of absolute distance measurements is reduced from 58.25 µm to 9.79 µm, and the maximum relative displacement deviation decreases from 42.97 µm to 11.56 µm. Furthermore, the velocity measurement precision for dynamic targets is improved by a factor of 2.61 to 5.75.
Journal article
(2025)
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Brice Meulah, Pytsje T. Hoekstra, Gleb Vdovine, Jan Carel Diehl, Temitope Agbana, Louise Makau-Barasa, Jacob Solomon, Samuel Popoola, Satyajith Jujjavarapu, Moses Aderogba, Joseph O. Fadare, John A. Omotayo, David Bell, Cornelis H. Hokke, Lisette van Lieshout
Introduction: Schistosomiasis is a public health concern and there is a need for reliable field-compatible diagnostic methods in endemic settings. The AiDx Assist, an artificial intelligence (AI)-based automated microscope, has shown promising results for the detection of Schistosoma haematobium eggs in urine. It has been further developed to detect Schistosoma mansoni eggs in stool.
Methods: In this study, we evaluated the performance of the AiDx Assist for the detection of S. mansoni eggs in stool samples and further validated the performance of the AiDx Assist for the detection of S. haematobium eggs in urine samples. Additionally, the potential of the AiDx Assist for the detection of other helminths in stool samples was explored. In total, 405 participants from an area endemic for both S. mansoni and S. haematobium provided stool and urine samples which were subjected to AiDx Assist (semi- and fully automated), while conventional microscopy was used as the diagnostic reference.
Results: Only samples with complete test results were included in the final analysis, resulting in 375 stool and 398 urine samples, of which 38.4% and 65.3% showed Schistosoma eggs by conventional microscopy. The collected images of the stool samples were retrospectively examined for other helminth eggs via manual analysis. For the detection of S. mansoni eggs, the sensitivity of the semi-automated AiDx Assist (86.8%) was significantly higher compared to the fully automated AiDx Assist (56.9%) while the specificity was comparable, with 81.4% and 86.8%, respectively. Retrospectively, eggs of Ascaris lumbricoides and Trichuris trichiura were visualized. For the examination of urine samples, a comparable sensitivity in the detection of S. haematobium eggs was found between the semi-and the fully automated modes of the AiDx Assist, showing 94.6% and 91.9%, respectively. Furthermore, the specificity was comparable, with 90.6%and 91.3% respectively.
Discussion: The AiDx Assist met the World Health Organization Target Product Profile criteria in terms of diagnostic accuracy for the detection of S. haematobium eggs in urine samples and performed modestly in the detection of S. mansoni eggs in stool samples. With some further improvements, it has the potential to become a valuable diagnostic tool for screening multiple helminth parasites in stool and urine samples. ...
Methods: In this study, we evaluated the performance of the AiDx Assist for the detection of S. mansoni eggs in stool samples and further validated the performance of the AiDx Assist for the detection of S. haematobium eggs in urine samples. Additionally, the potential of the AiDx Assist for the detection of other helminths in stool samples was explored. In total, 405 participants from an area endemic for both S. mansoni and S. haematobium provided stool and urine samples which were subjected to AiDx Assist (semi- and fully automated), while conventional microscopy was used as the diagnostic reference.
Results: Only samples with complete test results were included in the final analysis, resulting in 375 stool and 398 urine samples, of which 38.4% and 65.3% showed Schistosoma eggs by conventional microscopy. The collected images of the stool samples were retrospectively examined for other helminth eggs via manual analysis. For the detection of S. mansoni eggs, the sensitivity of the semi-automated AiDx Assist (86.8%) was significantly higher compared to the fully automated AiDx Assist (56.9%) while the specificity was comparable, with 81.4% and 86.8%, respectively. Retrospectively, eggs of Ascaris lumbricoides and Trichuris trichiura were visualized. For the examination of urine samples, a comparable sensitivity in the detection of S. haematobium eggs was found between the semi-and the fully automated modes of the AiDx Assist, showing 94.6% and 91.9%, respectively. Furthermore, the specificity was comparable, with 90.6%and 91.3% respectively.
Discussion: The AiDx Assist met the World Health Organization Target Product Profile criteria in terms of diagnostic accuracy for the detection of S. haematobium eggs in urine samples and performed modestly in the detection of S. mansoni eggs in stool samples. With some further improvements, it has the potential to become a valuable diagnostic tool for screening multiple helminth parasites in stool and urine samples. ...
Introduction: Schistosomiasis is a public health concern and there is a need for reliable field-compatible diagnostic methods in endemic settings. The AiDx Assist, an artificial intelligence (AI)-based automated microscope, has shown promising results for the detection of Schistosoma haematobium eggs in urine. It has been further developed to detect Schistosoma mansoni eggs in stool.
Methods: In this study, we evaluated the performance of the AiDx Assist for the detection of S. mansoni eggs in stool samples and further validated the performance of the AiDx Assist for the detection of S. haematobium eggs in urine samples. Additionally, the potential of the AiDx Assist for the detection of other helminths in stool samples was explored. In total, 405 participants from an area endemic for both S. mansoni and S. haematobium provided stool and urine samples which were subjected to AiDx Assist (semi- and fully automated), while conventional microscopy was used as the diagnostic reference.
Results: Only samples with complete test results were included in the final analysis, resulting in 375 stool and 398 urine samples, of which 38.4% and 65.3% showed Schistosoma eggs by conventional microscopy. The collected images of the stool samples were retrospectively examined for other helminth eggs via manual analysis. For the detection of S. mansoni eggs, the sensitivity of the semi-automated AiDx Assist (86.8%) was significantly higher compared to the fully automated AiDx Assist (56.9%) while the specificity was comparable, with 81.4% and 86.8%, respectively. Retrospectively, eggs of Ascaris lumbricoides and Trichuris trichiura were visualized. For the examination of urine samples, a comparable sensitivity in the detection of S. haematobium eggs was found between the semi-and the fully automated modes of the AiDx Assist, showing 94.6% and 91.9%, respectively. Furthermore, the specificity was comparable, with 90.6%and 91.3% respectively.
Discussion: The AiDx Assist met the World Health Organization Target Product Profile criteria in terms of diagnostic accuracy for the detection of S. haematobium eggs in urine samples and performed modestly in the detection of S. mansoni eggs in stool samples. With some further improvements, it has the potential to become a valuable diagnostic tool for screening multiple helminth parasites in stool and urine samples.
Methods: In this study, we evaluated the performance of the AiDx Assist for the detection of S. mansoni eggs in stool samples and further validated the performance of the AiDx Assist for the detection of S. haematobium eggs in urine samples. Additionally, the potential of the AiDx Assist for the detection of other helminths in stool samples was explored. In total, 405 participants from an area endemic for both S. mansoni and S. haematobium provided stool and urine samples which were subjected to AiDx Assist (semi- and fully automated), while conventional microscopy was used as the diagnostic reference.
Results: Only samples with complete test results were included in the final analysis, resulting in 375 stool and 398 urine samples, of which 38.4% and 65.3% showed Schistosoma eggs by conventional microscopy. The collected images of the stool samples were retrospectively examined for other helminth eggs via manual analysis. For the detection of S. mansoni eggs, the sensitivity of the semi-automated AiDx Assist (86.8%) was significantly higher compared to the fully automated AiDx Assist (56.9%) while the specificity was comparable, with 81.4% and 86.8%, respectively. Retrospectively, eggs of Ascaris lumbricoides and Trichuris trichiura were visualized. For the examination of urine samples, a comparable sensitivity in the detection of S. haematobium eggs was found between the semi-and the fully automated modes of the AiDx Assist, showing 94.6% and 91.9%, respectively. Furthermore, the specificity was comparable, with 90.6%and 91.3% respectively.
Discussion: The AiDx Assist met the World Health Organization Target Product Profile criteria in terms of diagnostic accuracy for the detection of S. haematobium eggs in urine samples and performed modestly in the detection of S. mansoni eggs in stool samples. With some further improvements, it has the potential to become a valuable diagnostic tool for screening multiple helminth parasites in stool and urine samples.
Journal article
(2025)
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Wenjun Chen, Xiaoping Li, Gleb Vdovin, Zhongwen Deng, Shuwei Zhang, Haifeng Sun, Lin Li, Hengkang Zhang, Li Wang, Hai Gong, Herman Koara
Frequency-sweeping interferometry (FSI) is an advanced coherent measurement technique capable of simultaneous high-precision measurement of dynamic target absolute distance and velocity. This study reveals that the dynamic target modulates the beat signal in FSI, causing the phase jump phenomenon in the beat signal and subsequent measurement failures. We theoretically derive and experimentally validate the conditions for phase jumps. Additionally, we propose using time-frequency analysis methods to detect phase jump instants and reconstruct the instantaneous frequency trajectory of the beat signal modulated by phase jumps. Experimental results show that even with phase jumps, we achieved a dynamic velocity measurement of −135.40 mm/s on a 0.5 m baseline, surpassing the theoretical limit of −4.40 mm/s under this baseline, while maintaining effective measurement capability on an extended 10 m baseline. The discovery and resolution of phase jumps are expected to overcome velocity limitation in FSI, significantly expanding its velocity measurement range.
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Frequency-sweeping interferometry (FSI) is an advanced coherent measurement technique capable of simultaneous high-precision measurement of dynamic target absolute distance and velocity. This study reveals that the dynamic target modulates the beat signal in FSI, causing the phase jump phenomenon in the beat signal and subsequent measurement failures. We theoretically derive and experimentally validate the conditions for phase jumps. Additionally, we propose using time-frequency analysis methods to detect phase jump instants and reconstruct the instantaneous frequency trajectory of the beat signal modulated by phase jumps. Experimental results show that even with phase jumps, we achieved a dynamic velocity measurement of −135.40 mm/s on a 0.5 m baseline, surpassing the theoretical limit of −4.40 mm/s under this baseline, while maintaining effective measurement capability on an extended 10 m baseline. The discovery and resolution of phase jumps are expected to overcome velocity limitation in FSI, significantly expanding its velocity measurement range.
Journal article
(2025)
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Prosper Oyibo, Brice Meulah, Tope Agbana, Lisette van Lieshout, Wellington Oyibo, Gleb Vdovin, Jan Carel Diehl
In this work, we developed an automated system for the detection and classification of soil-transmitted helminths (STH) and Schistosoma (S.) mansoni eggs in microscopic images of fecal smears. We assembled an STH and S. mansoni dataset comprising over 3,000 field-of-view (FOV) images containing parasite eggs, extracted from more than 300 fecal smear prepared using the Kato-Katz technique. These images were acquired using Schistoscope—a cost-effective automated digital microscope. After annotating the STH and S. mansoni eggs, we employed a transfer learning approach to train an EfficientDet deep learning model, using 70% of the dataset for training, 20% for validation, and 10% for testing. The developed model successfully identified STH and S. mansoni eggs in the FOV images, achieving weighted average scores of Precision, Sensitivity, Specificity, and F-Score across four classes of helminths (A. lumbricoides, T. trichiura, hookworm, and S. mansoni). Our system highlights the potential of the Schistoscope, enhanced with artificial intelligence, for detecting STH and S. mansoni infections in remote, resource-limited settings and for supporting the monitoring and evaluation of neglected tropical disease (NTD) control programs.
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In this work, we developed an automated system for the detection and classification of soil-transmitted helminths (STH) and Schistosoma (S.) mansoni eggs in microscopic images of fecal smears. We assembled an STH and S. mansoni dataset comprising over 3,000 field-of-view (FOV) images containing parasite eggs, extracted from more than 300 fecal smear prepared using the Kato-Katz technique. These images were acquired using Schistoscope—a cost-effective automated digital microscope. After annotating the STH and S. mansoni eggs, we employed a transfer learning approach to train an EfficientDet deep learning model, using 70% of the dataset for training, 20% for validation, and 10% for testing. The developed model successfully identified STH and S. mansoni eggs in the FOV images, achieving weighted average scores of Precision, Sensitivity, Specificity, and F-Score across four classes of helminths (A. lumbricoides, T. trichiura, hookworm, and S. mansoni). Our system highlights the potential of the Schistoscope, enhanced with artificial intelligence, for detecting STH and S. mansoni infections in remote, resource-limited settings and for supporting the monitoring and evaluation of neglected tropical disease (NTD) control programs.
Schistosomiasis and Soil Transmitted Helminthiasis Among School Age Children
Impact of 3–5 Annual Rounds of Mass Drug Administration in Ekiti State, Southwest Nigeria
Journal article
(2025)
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Solomon M. Jacob, Jan-Carel Diehl, Gleb Vdovine, Temitope Agbana, Samuel Popoola, Satyajith Jujjavarapu, David Bell, Akande O. Ajayi, Joseph O. Fadare, More authors...
Background: Schistosomiasis (SCH) and soil transmitted helminthiasis (STH) have been targeted for elimination as a public health problem (EPHP) within the World Health Organization (WHO)’s Roadmap for Neglected Tropical Diseases (NTDs) 2021–2030. One of the global strategies for the control and elimination of these diseases is the mass administration of praziquantel and albendazole/mebendazole without prior individual diagnosis. To measure the progress towards the 2030 target, we conducted an assessment to determine the impact of the 3–5 rounds of annual mass drug administration among school age children in Ekiti State. Such scientific insights into the impact of these treatments will facilitate improved planning and targeting of resources towards reaching the last mile. Methodology: This assessment was conducted in 16 local government areas (LGAs) of Ekiti State between October and November 2023. Samples were collected from pupils in 166 primary and junior secondary schools across 166 wards of the State. Urine and stool samples were collected from 7670 pupils of ages 5 to 14 years, following standard laboratory procedures. Urine membrane filtration techniques were used for urine preparation while the Kato–Katz technique was used for stool preparation. A novel AiDx digital microscope was used to examine the presence of any ova in the prepared specimen. Parasite ova in urine were reported as the number of ova/10 mL of urine, and were categorized as light infection (˂50 ova/10 mL of urine) or heavy infection (>50 ova/10 mL of urine) while ova of parasites in stool samples were reported as eggs per gram of stool (EPG) and categorized into light, moderate and heavy infection. Results: Overall, 0.76% (0.56–0.95) at 95% CI of the 7670 respondents were infected with Schistosomia haematobium. No Schistosoma mansoni infection was recorded in the study. Similarly, 3.9% (3.43–4.29) at 95% CI were infected with STHs. The overall prevalence of schistosomiasis had significantly reduced from 8.2% in 2008 to 0.8%, while the overall prevalence of STHs significantly reduced from 30.9% to 3.9% with Ascaris lumbricoides being the dominant species of STH. In the 16 LGAs assessed, Ekiti West had the highest S. haematobium prevalence of 4.26%. Ise/Orun and Oye ranked second and third with a prevalence of 3.48% and 2.40% respectively, while all other LGAs had <1% prevalence. The prevalence of STHs was highest in Ekiti-West with a prevalence of 10.45% while Emure and Ikole Local Governments had the lowest prevalence of 0.31% and 0.38%, respectively. There was no significant difference in the prevalence of schistosomiasis between male (0.76%) and female (0.75%) as p ≥ 0.05. Similarly, the difference in prevalence for STH among males (3.95%) was not significantly different from their female counterparts (3.77%), p ≥ 0.05. Conclusions: Based on the WHO guidelines, this study demonstrated that only three LGAs require continued MDA every 2/3 years, seven require only surveillance while six are now non-endemic for schistosomiasis. Similarly, two of the LGAs require one round of MDA yearly, eight LGAs need one round of MDA every two to three years and six LGAs are now below the treatment threshold and no longer require treatment for STH.
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Background: Schistosomiasis (SCH) and soil transmitted helminthiasis (STH) have been targeted for elimination as a public health problem (EPHP) within the World Health Organization (WHO)’s Roadmap for Neglected Tropical Diseases (NTDs) 2021–2030. One of the global strategies for the control and elimination of these diseases is the mass administration of praziquantel and albendazole/mebendazole without prior individual diagnosis. To measure the progress towards the 2030 target, we conducted an assessment to determine the impact of the 3–5 rounds of annual mass drug administration among school age children in Ekiti State. Such scientific insights into the impact of these treatments will facilitate improved planning and targeting of resources towards reaching the last mile. Methodology: This assessment was conducted in 16 local government areas (LGAs) of Ekiti State between October and November 2023. Samples were collected from pupils in 166 primary and junior secondary schools across 166 wards of the State. Urine and stool samples were collected from 7670 pupils of ages 5 to 14 years, following standard laboratory procedures. Urine membrane filtration techniques were used for urine preparation while the Kato–Katz technique was used for stool preparation. A novel AiDx digital microscope was used to examine the presence of any ova in the prepared specimen. Parasite ova in urine were reported as the number of ova/10 mL of urine, and were categorized as light infection (˂50 ova/10 mL of urine) or heavy infection (>50 ova/10 mL of urine) while ova of parasites in stool samples were reported as eggs per gram of stool (EPG) and categorized into light, moderate and heavy infection. Results: Overall, 0.76% (0.56–0.95) at 95% CI of the 7670 respondents were infected with Schistosomia haematobium. No Schistosoma mansoni infection was recorded in the study. Similarly, 3.9% (3.43–4.29) at 95% CI were infected with STHs. The overall prevalence of schistosomiasis had significantly reduced from 8.2% in 2008 to 0.8%, while the overall prevalence of STHs significantly reduced from 30.9% to 3.9% with Ascaris lumbricoides being the dominant species of STH. In the 16 LGAs assessed, Ekiti West had the highest S. haematobium prevalence of 4.26%. Ise/Orun and Oye ranked second and third with a prevalence of 3.48% and 2.40% respectively, while all other LGAs had <1% prevalence. The prevalence of STHs was highest in Ekiti-West with a prevalence of 10.45% while Emure and Ikole Local Governments had the lowest prevalence of 0.31% and 0.38%, respectively. There was no significant difference in the prevalence of schistosomiasis between male (0.76%) and female (0.75%) as p ≥ 0.05. Similarly, the difference in prevalence for STH among males (3.95%) was not significantly different from their female counterparts (3.77%), p ≥ 0.05. Conclusions: Based on the WHO guidelines, this study demonstrated that only three LGAs require continued MDA every 2/3 years, seven require only surveillance while six are now non-endemic for schistosomiasis. Similarly, two of the LGAs require one round of MDA yearly, eight LGAs need one round of MDA every two to three years and six LGAs are now below the treatment threshold and no longer require treatment for STH.
Community Mobilisation for Human Sample Collection in Sensitive Communities
Experiences from Granular Mapping of Schistosomiasis and Soil-Transmitted Helminths in Ekiti State, South West, Nigeria
Journal article
(2024)
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Temitope Agbana, Omolade Omotade, Moses O. Aderogba, David Bell, Jacob Solomon, Saheed Animashaun, Peace Alabi, Jan-Carel Diehl, Gleb Vdovine, More Authors...
Community mobilisation is a vital process for raising awareness and increasing participation in healthcare interventions, research, and programmes that require human sample collection and mass management. In this report, we present the community mobilisation approach undertaken for the implementation of the operational mapping and assessment of granular schistosomiasis and soil-transmitted helminths in Ekiti State, Nigeria. The mobilisation was conducted in 177 communities/wards of the 16 local government areas. A total of 15,340 urine and stool samples were collected in 34 days. The efficacy and success of the strategy were evaluated through the following three performance metrics: community compliance rate, the participant response rate at the community level, and the overall compliance response rate of the four most sensitive LGAs. Community compliance was 93.7% as sample collection was denied in nine communities and two other communities demanded the return of the collected samples despite our mobilisation effort because of cultural bias and myths that connect the collection of stool and urine samples to ritual activities in the local context. The participant response rate at the community level was 86.7%. Three of the four sensitive LGAs (based on previous assessment programmes) demonstrated satisfactory compliance rates of 100%, while a response rate of 64.0% was computed for one of the LGAs. We believe our approach contributed to effective community mobilisation and awareness and that the developed model has the potential to improve participation rates in large healthcare assessments and intervention programmes.
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Community mobilisation is a vital process for raising awareness and increasing participation in healthcare interventions, research, and programmes that require human sample collection and mass management. In this report, we present the community mobilisation approach undertaken for the implementation of the operational mapping and assessment of granular schistosomiasis and soil-transmitted helminths in Ekiti State, Nigeria. The mobilisation was conducted in 177 communities/wards of the 16 local government areas. A total of 15,340 urine and stool samples were collected in 34 days. The efficacy and success of the strategy were evaluated through the following three performance metrics: community compliance rate, the participant response rate at the community level, and the overall compliance response rate of the four most sensitive LGAs. Community compliance was 93.7% as sample collection was denied in nine communities and two other communities demanded the return of the collected samples despite our mobilisation effort because of cultural bias and myths that connect the collection of stool and urine samples to ritual activities in the local context. The participant response rate at the community level was 86.7%. Three of the four sensitive LGAs (based on previous assessment programmes) demonstrated satisfactory compliance rates of 100%, while a response rate of 64.0% was computed for one of the LGAs. We believe our approach contributed to effective community mobilisation and awareness and that the developed model has the potential to improve participation rates in large healthcare assessments and intervention programmes.
Journal article
(2024)
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P.O. Oyibo, T.E. Agbana, Lisette van Lieshout, Wellington Oyibo, J.C. Diehl, Gleb Vdovin
Traditionally, automated slide scanning involves capturing a rectangular grid of field-of-view (FoV) images which can be stitched together to create whole slide images, while the autofocusing algorithm captures a focal stack of images
to determine the best in-focus image. However, these methods can be timeconsuming due to the need for X-, Y- and Z-axis movements of the digital microscope while capturing multiple FoV images. In this paper, we propose a solution to minimise these redundancies by presenting an optimal procedure for automated slide scanning of circular membrane filters on a glass slide. We achieve this by following an optimal path in the sample plane, ensuring that only FoVs overlapping the filter membrane are captured. To capture the best infocus FoV image, we utilise a hill-climbing approach that tracks the peak of the mean of Gaussian gradient of the captured FoVs images along the Z-axis. We implemented this procedure to optimise the efficiency of the Schistoscope, an automated digital microscope developed to diagnose urogenital schistosomiasis by imaging Schistosoma haematobium eggs on 13 or 25 mm membrane filters. Our improved method reduces the automated slide scanning time by 63.18%and 72.52% for the respective filter sizes. This advancement greatly supportsthe practicality of the Schistoscope in large-scale schistosomiasis monitoringand evaluation programs in endemic regions. This will save time, resources andalso accelerate generation of data that is critical in achieving the targets for schistosomiasis elimination. ...
to determine the best in-focus image. However, these methods can be timeconsuming due to the need for X-, Y- and Z-axis movements of the digital microscope while capturing multiple FoV images. In this paper, we propose a solution to minimise these redundancies by presenting an optimal procedure for automated slide scanning of circular membrane filters on a glass slide. We achieve this by following an optimal path in the sample plane, ensuring that only FoVs overlapping the filter membrane are captured. To capture the best infocus FoV image, we utilise a hill-climbing approach that tracks the peak of the mean of Gaussian gradient of the captured FoVs images along the Z-axis. We implemented this procedure to optimise the efficiency of the Schistoscope, an automated digital microscope developed to diagnose urogenital schistosomiasis by imaging Schistosoma haematobium eggs on 13 or 25 mm membrane filters. Our improved method reduces the automated slide scanning time by 63.18%and 72.52% for the respective filter sizes. This advancement greatly supportsthe practicality of the Schistoscope in large-scale schistosomiasis monitoringand evaluation programs in endemic regions. This will save time, resources andalso accelerate generation of data that is critical in achieving the targets for schistosomiasis elimination. ...
Traditionally, automated slide scanning involves capturing a rectangular grid of field-of-view (FoV) images which can be stitched together to create whole slide images, while the autofocusing algorithm captures a focal stack of images
to determine the best in-focus image. However, these methods can be timeconsuming due to the need for X-, Y- and Z-axis movements of the digital microscope while capturing multiple FoV images. In this paper, we propose a solution to minimise these redundancies by presenting an optimal procedure for automated slide scanning of circular membrane filters on a glass slide. We achieve this by following an optimal path in the sample plane, ensuring that only FoVs overlapping the filter membrane are captured. To capture the best infocus FoV image, we utilise a hill-climbing approach that tracks the peak of the mean of Gaussian gradient of the captured FoVs images along the Z-axis. We implemented this procedure to optimise the efficiency of the Schistoscope, an automated digital microscope developed to diagnose urogenital schistosomiasis by imaging Schistosoma haematobium eggs on 13 or 25 mm membrane filters. Our improved method reduces the automated slide scanning time by 63.18%and 72.52% for the respective filter sizes. This advancement greatly supportsthe practicality of the Schistoscope in large-scale schistosomiasis monitoringand evaluation programs in endemic regions. This will save time, resources andalso accelerate generation of data that is critical in achieving the targets for schistosomiasis elimination.
to determine the best in-focus image. However, these methods can be timeconsuming due to the need for X-, Y- and Z-axis movements of the digital microscope while capturing multiple FoV images. In this paper, we propose a solution to minimise these redundancies by presenting an optimal procedure for automated slide scanning of circular membrane filters on a glass slide. We achieve this by following an optimal path in the sample plane, ensuring that only FoVs overlapping the filter membrane are captured. To capture the best infocus FoV image, we utilise a hill-climbing approach that tracks the peak of the mean of Gaussian gradient of the captured FoVs images along the Z-axis. We implemented this procedure to optimise the efficiency of the Schistoscope, an automated digital microscope developed to diagnose urogenital schistosomiasis by imaging Schistosoma haematobium eggs on 13 or 25 mm membrane filters. Our improved method reduces the automated slide scanning time by 63.18%and 72.52% for the respective filter sizes. This advancement greatly supportsthe practicality of the Schistoscope in large-scale schistosomiasis monitoringand evaluation programs in endemic regions. This will save time, resources andalso accelerate generation of data that is critical in achieving the targets for schistosomiasis elimination.
Journal article
(2023)
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Prosper Oyibo, Brice Meulah, Michel Bengtson, Lisette van Lieshout, Wellington Oyibo, Jan-Carel Diehl, Gleb Vdovine, Temitope E. Agbana
Purpose: Automated diagnosis of urogenital schistosomiasis using digital microscopy images of urine slides is an essential step toward the elimination of schistosomiasis as a disease of public health concern in Sub-Saharan African countries. We create a robust image dataset of urine samples obtained from field settings and develop a two-stage diagnosis framework for urogenital schistosomiasis.
Approach: Urine samples obtained from field settings were captured using the Schistoscope device, and S. haematobium eggs present in the images were manually annotated by experts to create the SH dataset. Next, we develop a two-stage diagnosis framework, which consists of semantic segmentation of S. haematobium eggs using the DeepLabv3-MobileNetV3 deep convolutional neural network and a refined segmentation step using ellipse fitting approach to approximate the eggs with an automatically determined number of ellipses. We defined two linear inequality constraints as a function of the overlap coefficient and area of a fitted ellipses. False positive diagnosis resulting from over-segmentation was further minimized using these constraints. We evaluated the performance of our framework on 7605 images from 65 independent urine samples collected from field settings in Nigeria, by deploying our algorithm on an Edge AI system consisting of Raspberry Pi + Coral USB accelerator.
Result: The SH dataset contains 12,051 images from 103 independent urine samples and the developed urogenital schistosomiasis diagnosis framework achieved clinical sensitivity, specificity, and precision of 93.8%, 93.9%, and 93.8%, respectively, using results from an experienced microscopist as reference.
Conclusion: Our detection framework is a promising tool for the diagnosis of urogenital schistosomiasis as our results meet the World Health Organization target product profile requirements for monitoring and evaluation of schistosomiasis control programs.
...
Approach: Urine samples obtained from field settings were captured using the Schistoscope device, and S. haematobium eggs present in the images were manually annotated by experts to create the SH dataset. Next, we develop a two-stage diagnosis framework, which consists of semantic segmentation of S. haematobium eggs using the DeepLabv3-MobileNetV3 deep convolutional neural network and a refined segmentation step using ellipse fitting approach to approximate the eggs with an automatically determined number of ellipses. We defined two linear inequality constraints as a function of the overlap coefficient and area of a fitted ellipses. False positive diagnosis resulting from over-segmentation was further minimized using these constraints. We evaluated the performance of our framework on 7605 images from 65 independent urine samples collected from field settings in Nigeria, by deploying our algorithm on an Edge AI system consisting of Raspberry Pi + Coral USB accelerator.
Result: The SH dataset contains 12,051 images from 103 independent urine samples and the developed urogenital schistosomiasis diagnosis framework achieved clinical sensitivity, specificity, and precision of 93.8%, 93.9%, and 93.8%, respectively, using results from an experienced microscopist as reference.
Conclusion: Our detection framework is a promising tool for the diagnosis of urogenital schistosomiasis as our results meet the World Health Organization target product profile requirements for monitoring and evaluation of schistosomiasis control programs.
...
Purpose: Automated diagnosis of urogenital schistosomiasis using digital microscopy images of urine slides is an essential step toward the elimination of schistosomiasis as a disease of public health concern in Sub-Saharan African countries. We create a robust image dataset of urine samples obtained from field settings and develop a two-stage diagnosis framework for urogenital schistosomiasis.
Approach: Urine samples obtained from field settings were captured using the Schistoscope device, and S. haematobium eggs present in the images were manually annotated by experts to create the SH dataset. Next, we develop a two-stage diagnosis framework, which consists of semantic segmentation of S. haematobium eggs using the DeepLabv3-MobileNetV3 deep convolutional neural network and a refined segmentation step using ellipse fitting approach to approximate the eggs with an automatically determined number of ellipses. We defined two linear inequality constraints as a function of the overlap coefficient and area of a fitted ellipses. False positive diagnosis resulting from over-segmentation was further minimized using these constraints. We evaluated the performance of our framework on 7605 images from 65 independent urine samples collected from field settings in Nigeria, by deploying our algorithm on an Edge AI system consisting of Raspberry Pi + Coral USB accelerator.
Result: The SH dataset contains 12,051 images from 103 independent urine samples and the developed urogenital schistosomiasis diagnosis framework achieved clinical sensitivity, specificity, and precision of 93.8%, 93.9%, and 93.8%, respectively, using results from an experienced microscopist as reference.
Conclusion: Our detection framework is a promising tool for the diagnosis of urogenital schistosomiasis as our results meet the World Health Organization target product profile requirements for monitoring and evaluation of schistosomiasis control programs.
Approach: Urine samples obtained from field settings were captured using the Schistoscope device, and S. haematobium eggs present in the images were manually annotated by experts to create the SH dataset. Next, we develop a two-stage diagnosis framework, which consists of semantic segmentation of S. haematobium eggs using the DeepLabv3-MobileNetV3 deep convolutional neural network and a refined segmentation step using ellipse fitting approach to approximate the eggs with an automatically determined number of ellipses. We defined two linear inequality constraints as a function of the overlap coefficient and area of a fitted ellipses. False positive diagnosis resulting from over-segmentation was further minimized using these constraints. We evaluated the performance of our framework on 7605 images from 65 independent urine samples collected from field settings in Nigeria, by deploying our algorithm on an Edge AI system consisting of Raspberry Pi + Coral USB accelerator.
Result: The SH dataset contains 12,051 images from 103 independent urine samples and the developed urogenital schistosomiasis diagnosis framework achieved clinical sensitivity, specificity, and precision of 93.8%, 93.9%, and 93.8%, respectively, using results from an experienced microscopist as reference.
Conclusion: Our detection framework is a promising tool for the diagnosis of urogenital schistosomiasis as our results meet the World Health Organization target product profile requirements for monitoring and evaluation of schistosomiasis control programs.
Journal article
(2023)
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Louise Makau-Barasa, Liya Assefa, Jacob Solomon, Juliana A-Enegela, James G. Damen, Samuel Popoola, Jan‑Carel Diehl, Gleb Vdovin, Temitope Agbana, More Authors...
In this research, we report on the performance of automated optical digital detection and quantification of Schistosoma haematobium provided by AiDx NTDx multi-diagnostic Assist microscope. Our study was community-based, and a convenient sampling method was used in 17 communities in Abuja Nigeria, based on the disease prevalence information extracted from the baseline database on schistosomiasis, NTD Division, of the Federal Ministry of Health. At baseline, samples from 869 participants were evaluated of which 358 (34.1%) tested S. haematobium positive by the reference diagnostic standard. Registered images from the fully automated (autofocusing, scanning, image registration and processing, AI image analysis and automatic parasite count) AiDx assist microscope were analyzed. The Semi automated (autofocusing, scanning, image registration & processing and manual parasite count) and the fully automated AiDx Assist showed comparable sensitivities and specificities of [90.3%, 98%] and [89%, 99%] respectively. Overall, estimated egg counts of the semi-automated & fully automated AiDx Assist correlated significantly with the egg counts of conventional microscopy (r = 0.93, p ≤ 0.001 and r = 0.89, p ≤ 0.001 respectively). The AiDx Assist device performance is consistent with requirement of the World Health Organization diagnostic target product profile for monitoring, evaluation, and surveillance of Schistosomiasis elimination Programs.
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In this research, we report on the performance of automated optical digital detection and quantification of Schistosoma haematobium provided by AiDx NTDx multi-diagnostic Assist microscope. Our study was community-based, and a convenient sampling method was used in 17 communities in Abuja Nigeria, based on the disease prevalence information extracted from the baseline database on schistosomiasis, NTD Division, of the Federal Ministry of Health. At baseline, samples from 869 participants were evaluated of which 358 (34.1%) tested S. haematobium positive by the reference diagnostic standard. Registered images from the fully automated (autofocusing, scanning, image registration and processing, AI image analysis and automatic parasite count) AiDx assist microscope were analyzed. The Semi automated (autofocusing, scanning, image registration & processing and manual parasite count) and the fully automated AiDx Assist showed comparable sensitivities and specificities of [90.3%, 98%] and [89%, 99%] respectively. Overall, estimated egg counts of the semi-automated & fully automated AiDx Assist correlated significantly with the egg counts of conventional microscopy (r = 0.93, p ≤ 0.001 and r = 0.89, p ≤ 0.001 respectively). The AiDx Assist device performance is consistent with requirement of the World Health Organization diagnostic target product profile for monitoring, evaluation, and surveillance of Schistosomiasis elimination Programs.
Report
(2022)
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Louise Makau-Barasa, Moses O. Aderogba, David Bell, Samuel Popoola, T.E. Agbana, J.C. Diehl, Gleb Vdovin
To achieve the WHO’s goal of sustained elimination of Lymphatic Filariasis disease, there is the need for accurate diagnostic device especially in areas of low-intensity infections. This project, which is a collaboration of the Nigerian Federal Ministry of Health (FMoH), AiDx and funded by THE END FUND is exploring the performance capacity of the novel AiDx_NTDx Assist automated microscope in the detection of microfilaria – Wuchereria bancrofti in prepared blood samples (glass slides) using standard microscopy as a reference. The prevalence of circulating Wuchereria bancrofti microfilaria in blood was assessed using automated Image based microscopy analysis for the detection of microfilariae in prepared blood smears.
1250 people in four LGAs of Ogun state, Nigeria participated in this study. All prepared blood samples analyzed by both expert manual microscopy and the AiDx NTDx Assist results showed that none of the 1250 participants samples analyzed had any presence of W. bancrofti microfilariae in their blood. Since no positive samples was detected by the reference test and the AiDx NTDx Assist, it was impossible to estimate the sensitivity of the device. However, based on the negative results obtained, the AiDx NTDx Assist showed a specificity of 100%, an accuracy of 100% and a Negative Predictive Value of 100%.
Despite the baseline report obtained from the National data base of the ministry of health, indicating the prevalence of 10%, 8.2%, 4.2% and 4% in the four local government areas where samples were collected, we were not able to find a participant with detectable microfilaria. Evaluation of the AiDx NTDx Assist device shows direct correlation with the expert manual microscopy. Although samples were taken in remote/rural areas of some of the LGA, e.g., Adodo Ota, result obtained however suggest a deviation from baseline and reality. This may be due to previous MDA undertaken in 2018 as reported by the state NTD officers. Further, thorough reassessment is therefore recommended . ...
1250 people in four LGAs of Ogun state, Nigeria participated in this study. All prepared blood samples analyzed by both expert manual microscopy and the AiDx NTDx Assist results showed that none of the 1250 participants samples analyzed had any presence of W. bancrofti microfilariae in their blood. Since no positive samples was detected by the reference test and the AiDx NTDx Assist, it was impossible to estimate the sensitivity of the device. However, based on the negative results obtained, the AiDx NTDx Assist showed a specificity of 100%, an accuracy of 100% and a Negative Predictive Value of 100%.
Despite the baseline report obtained from the National data base of the ministry of health, indicating the prevalence of 10%, 8.2%, 4.2% and 4% in the four local government areas where samples were collected, we were not able to find a participant with detectable microfilaria. Evaluation of the AiDx NTDx Assist device shows direct correlation with the expert manual microscopy. Although samples were taken in remote/rural areas of some of the LGA, e.g., Adodo Ota, result obtained however suggest a deviation from baseline and reality. This may be due to previous MDA undertaken in 2018 as reported by the state NTD officers. Further, thorough reassessment is therefore recommended . ...
To achieve the WHO’s goal of sustained elimination of Lymphatic Filariasis disease, there is the need for accurate diagnostic device especially in areas of low-intensity infections. This project, which is a collaboration of the Nigerian Federal Ministry of Health (FMoH), AiDx and funded by THE END FUND is exploring the performance capacity of the novel AiDx_NTDx Assist automated microscope in the detection of microfilaria – Wuchereria bancrofti in prepared blood samples (glass slides) using standard microscopy as a reference. The prevalence of circulating Wuchereria bancrofti microfilaria in blood was assessed using automated Image based microscopy analysis for the detection of microfilariae in prepared blood smears.
1250 people in four LGAs of Ogun state, Nigeria participated in this study. All prepared blood samples analyzed by both expert manual microscopy and the AiDx NTDx Assist results showed that none of the 1250 participants samples analyzed had any presence of W. bancrofti microfilariae in their blood. Since no positive samples was detected by the reference test and the AiDx NTDx Assist, it was impossible to estimate the sensitivity of the device. However, based on the negative results obtained, the AiDx NTDx Assist showed a specificity of 100%, an accuracy of 100% and a Negative Predictive Value of 100%.
Despite the baseline report obtained from the National data base of the ministry of health, indicating the prevalence of 10%, 8.2%, 4.2% and 4% in the four local government areas where samples were collected, we were not able to find a participant with detectable microfilaria. Evaluation of the AiDx NTDx Assist device shows direct correlation with the expert manual microscopy. Although samples were taken in remote/rural areas of some of the LGA, e.g., Adodo Ota, result obtained however suggest a deviation from baseline and reality. This may be due to previous MDA undertaken in 2018 as reported by the state NTD officers. Further, thorough reassessment is therefore recommended .
1250 people in four LGAs of Ogun state, Nigeria participated in this study. All prepared blood samples analyzed by both expert manual microscopy and the AiDx NTDx Assist results showed that none of the 1250 participants samples analyzed had any presence of W. bancrofti microfilariae in their blood. Since no positive samples was detected by the reference test and the AiDx NTDx Assist, it was impossible to estimate the sensitivity of the device. However, based on the negative results obtained, the AiDx NTDx Assist showed a specificity of 100%, an accuracy of 100% and a Negative Predictive Value of 100%.
Despite the baseline report obtained from the National data base of the ministry of health, indicating the prevalence of 10%, 8.2%, 4.2% and 4% in the four local government areas where samples were collected, we were not able to find a participant with detectable microfilaria. Evaluation of the AiDx NTDx Assist device shows direct correlation with the expert manual microscopy. Although samples were taken in remote/rural areas of some of the LGA, e.g., Adodo Ota, result obtained however suggest a deviation from baseline and reality. This may be due to previous MDA undertaken in 2018 as reported by the state NTD officers. Further, thorough reassessment is therefore recommended .
Journal article
(2022)
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P.O. Oyibo, S. Jujjavarapu, J.C. Diehl, Brice Meulah, T.E. Agbana, I.G. Braakman, Angela van Diepen, M.L. Bengtson, Lisette van Lieshout, Wellington Oyibo Andi, Gleb Vdovin
For many parasitic diseases, the microscopic examination of clinical samples such as urine and stool still serves as the diagnostic reference standard, primarily because microscopes are accessible and cost-effective. However, conventional microscopy is laborious, requires highly skilled personnel, and is highly subjective. Requirements for skilled operators, coupled with the cost and maintenance needs of the microscopes, which is hardly done in endemic countries, presents grossly limited access to the diagnosis of parasitic diseases in resource-limited settings. The urgent requirement for the management of tropical diseases such as schistosomiasis, which is now focused on elimination, has underscored the critical need for the creation of access to easy-to-use diagnosis for case detection, community mapping, and surveillance. In this paper, we present a low-cost automated digital microscope—the Schistoscope—which is capable of automatic focusing and scanning regions of interest in prepared microscope slides, and automatic detection of Schistosoma haematobium eggs in captured images. The device was developed using widely accessible distributed manufacturing methods and off-the-shelf components to enable local manufacturability and ease of maintenance. For proof of principle, we created a Schistosoma haematobium egg dataset of over 5000 images captured from spiked and clinical urine samples from field settings and demonstrated the automatic detection of Schistosoma haematobium eggs using a trained deep neural network model. The experiments and results presented in this paper collectively illustrate the robustness, stability, and optical performance of the device, making it suitable for use in the monitoring and evaluation of schistosomiasis control programs in endemic settings.
...
For many parasitic diseases, the microscopic examination of clinical samples such as urine and stool still serves as the diagnostic reference standard, primarily because microscopes are accessible and cost-effective. However, conventional microscopy is laborious, requires highly skilled personnel, and is highly subjective. Requirements for skilled operators, coupled with the cost and maintenance needs of the microscopes, which is hardly done in endemic countries, presents grossly limited access to the diagnosis of parasitic diseases in resource-limited settings. The urgent requirement for the management of tropical diseases such as schistosomiasis, which is now focused on elimination, has underscored the critical need for the creation of access to easy-to-use diagnosis for case detection, community mapping, and surveillance. In this paper, we present a low-cost automated digital microscope—the Schistoscope—which is capable of automatic focusing and scanning regions of interest in prepared microscope slides, and automatic detection of Schistosoma haematobium eggs in captured images. The device was developed using widely accessible distributed manufacturing methods and off-the-shelf components to enable local manufacturability and ease of maintenance. For proof of principle, we created a Schistosoma haematobium egg dataset of over 5000 images captured from spiked and clinical urine samples from field settings and demonstrated the automatic detection of Schistosoma haematobium eggs using a trained deep neural network model. The experiments and results presented in this paper collectively illustrate the robustness, stability, and optical performance of the device, making it suitable for use in the monitoring and evaluation of schistosomiasis control programs in endemic settings.
We have applied a combination of blind deconvolution and deep learning to the processing of Shack-Hartmann images.By using the intensity information contained in spot positions, and the fine structure of the separate images created by the lenslets,we have increased the sensitivity and resolution of the sensor over the limit defined by standard processing of spot displacements only.We also have demonstrated the applicability of the method to wavefront sensing using extended objects as a reference.
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We have applied a combination of blind deconvolution and deep learning to the processing of Shack-Hartmann images.By using the intensity information contained in spot positions, and the fine structure of the separate images created by the lenslets,we have increased the sensitivity and resolution of the sensor over the limit defined by standard processing of spot displacements only.We also have demonstrated the applicability of the method to wavefront sensing using extended objects as a reference.
Phase retrieval from overexposed PSF
A projection-based approach
Conference paper
(2022)
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Oleg Soloviev, Jacques Noom, Hieu Thao Nguyen, Gleb Vdovin, Michel Verhaegen
We investigate the general adjustment of projection-based phase retrieval algorithms for use with saturated data. In the phase retrieval problem, model fidelity of experimental data containing a non-zero background level, fixed pattern noise, or overexposure, often presents a serious obstacle for standard algorithms. Recently, it was shown that overexposure can help to increase the signal-to-noise ratio in AI applications. We present our first results in exploring this direction in the phase retrieval problem, using as an example the Gerchberg-Saxton algorithm with simulated data. The proposed method can find application in microscopy, characterisation of precise optical instruments, and machine vision applications of Industry4.0.
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We investigate the general adjustment of projection-based phase retrieval algorithms for use with saturated data. In the phase retrieval problem, model fidelity of experimental data containing a non-zero background level, fixed pattern noise, or overexposure, often presents a serious obstacle for standard algorithms. Recently, it was shown that overexposure can help to increase the signal-to-noise ratio in AI applications. We present our first results in exploring this direction in the phase retrieval problem, using as an example the Gerchberg-Saxton algorithm with simulated data. The proposed method can find application in microscopy, characterisation of precise optical instruments, and machine vision applications of Industry4.0.
Journal article
(2021)
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D.N. van Grootheest, T.E. Agbana, J.C. Diehl, Angela van Diepen, Vitalii Bezzubik, Gleb Vdovin
Significance: Particle field holography is a versatile technique to determine the size and distribution of moving or stationary particles in air or in a liquid without significant disturbance of the sample volume. Although this technique is applied in biological sample analysis, it is limited to small sample volumes, thus increasing the number of measurements per sample. In this work, we characterize the maximum achievable volume limit based on the specification of a given sensor to realize the development of a potentially low-cost, single-shot, large-volume holographic microscope.
Aim: We present mathematical formulas that will aid in the design and development and improve the focusing speed for the numerical reconstruction of registered holograms in particle field holographic microscopes. Our proposed methodology has potential application in the detection of Schistosoma haematobium eggs in human urine samples.
Approach: Using the Fraunhofer holography theory for opaque objects, we derived an exact formula for the maximum diffraction-limited volume for an in-line holographic setup. The proof-of-concept device built based on the derived formulas was experimentally validated with urine spiked with cultured Schistosoma haematobium eggs.
Results: Results obtained show that for urine spiked with Schistosoma haematobium eggs, the volume thickness is limited to several millimeters due to scattering properties of the sample. The distances of the target particles could be estimated directly from the hologram fringes.
Conclusion: The methodology proposed will aid in the development of large-volume holographic microscopes. ...
Aim: We present mathematical formulas that will aid in the design and development and improve the focusing speed for the numerical reconstruction of registered holograms in particle field holographic microscopes. Our proposed methodology has potential application in the detection of Schistosoma haematobium eggs in human urine samples.
Approach: Using the Fraunhofer holography theory for opaque objects, we derived an exact formula for the maximum diffraction-limited volume for an in-line holographic setup. The proof-of-concept device built based on the derived formulas was experimentally validated with urine spiked with cultured Schistosoma haematobium eggs.
Results: Results obtained show that for urine spiked with Schistosoma haematobium eggs, the volume thickness is limited to several millimeters due to scattering properties of the sample. The distances of the target particles could be estimated directly from the hologram fringes.
Conclusion: The methodology proposed will aid in the development of large-volume holographic microscopes. ...
Significance: Particle field holography is a versatile technique to determine the size and distribution of moving or stationary particles in air or in a liquid without significant disturbance of the sample volume. Although this technique is applied in biological sample analysis, it is limited to small sample volumes, thus increasing the number of measurements per sample. In this work, we characterize the maximum achievable volume limit based on the specification of a given sensor to realize the development of a potentially low-cost, single-shot, large-volume holographic microscope.
Aim: We present mathematical formulas that will aid in the design and development and improve the focusing speed for the numerical reconstruction of registered holograms in particle field holographic microscopes. Our proposed methodology has potential application in the detection of Schistosoma haematobium eggs in human urine samples.
Approach: Using the Fraunhofer holography theory for opaque objects, we derived an exact formula for the maximum diffraction-limited volume for an in-line holographic setup. The proof-of-concept device built based on the derived formulas was experimentally validated with urine spiked with cultured Schistosoma haematobium eggs.
Results: Results obtained show that for urine spiked with Schistosoma haematobium eggs, the volume thickness is limited to several millimeters due to scattering properties of the sample. The distances of the target particles could be estimated directly from the hologram fringes.
Conclusion: The methodology proposed will aid in the development of large-volume holographic microscopes.
Aim: We present mathematical formulas that will aid in the design and development and improve the focusing speed for the numerical reconstruction of registered holograms in particle field holographic microscopes. Our proposed methodology has potential application in the detection of Schistosoma haematobium eggs in human urine samples.
Approach: Using the Fraunhofer holography theory for opaque objects, we derived an exact formula for the maximum diffraction-limited volume for an in-line holographic setup. The proof-of-concept device built based on the derived formulas was experimentally validated with urine spiked with cultured Schistosoma haematobium eggs.
Results: Results obtained show that for urine spiked with Schistosoma haematobium eggs, the volume thickness is limited to several millimeters due to scattering properties of the sample. The distances of the target particles could be estimated directly from the hologram fringes.
Conclusion: The methodology proposed will aid in the development of large-volume holographic microscopes.
Conference paper
(2020)
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Tope Agbana, Patrick Nijman, M.D.B. Hoeboer, D.N. van Grootheest, Angela van Diepen, Lisette van Lieshout, Jan-Carel Diehl, Michel Verhaegen, Gleb Vdovin
We present a simple method for the diagnosis of urinary schistosomiasis using an in-line lensless holographic microscope combined with flow cytometry technique. Using simple image processing algorithms and binary image classifier, our system provides automated detection of Schistosoma haematobium eggs in infected urine samples. Registered hologram is reconstructed by applying backpropagation from sensor to sample plane and reconstructed image is automatically analysed for the presence of S. haematobium eggs. Designed for use in a resource-poor laboratory setting, our proposed method has been implemented using a Raspberry Pi computer. From pre-clinical test performed with human urine samples spiked with S. haematobium eggs (approximately 200 eggs per 12 ml of urine), we achieved a sensitivity and specificity of 50.6% and 98.6% respectively. Our proposed method requires no complex sample preparation methods making the system simple to operate and useable in point-of-care diagnosis of urinary schistosomiasis.This method can be optimized to complement existing diagnostic procedures for the detection of S. haematobium eggs and can be deployed to inaccessible remote areas.
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We present a simple method for the diagnosis of urinary schistosomiasis using an in-line lensless holographic microscope combined with flow cytometry technique. Using simple image processing algorithms and binary image classifier, our system provides automated detection of Schistosoma haematobium eggs in infected urine samples. Registered hologram is reconstructed by applying backpropagation from sensor to sample plane and reconstructed image is automatically analysed for the presence of S. haematobium eggs. Designed for use in a resource-poor laboratory setting, our proposed method has been implemented using a Raspberry Pi computer. From pre-clinical test performed with human urine samples spiked with S. haematobium eggs (approximately 200 eggs per 12 ml of urine), we achieved a sensitivity and specificity of 50.6% and 98.6% respectively. Our proposed method requires no complex sample preparation methods making the system simple to operate and useable in point-of-care diagnosis of urinary schistosomiasis.This method can be optimized to complement existing diagnostic procedures for the detection of S. haematobium eggs and can be deployed to inaccessible remote areas.
Conference paper
(2020)
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Alex Heemels, Tope Agbana, Silvania Pereira, Jan-Carel Diehl, Michel Verhaegen, Gleb Vdovin
Fourier Ptychography is a computational imaging technique able to decouple high resolution from wide field of view, bypassing the diffraction limit of the microscope. Since it does not rely on high precision mechanics or fluorescent imaging, it is of practical interest for implementation in low scale devices. Despite its gains, realizing a functional low-cost setup working at the theoretical limits is challenging due to many factors causing discrepancies between theory and practice. Misalignment of the light emitting diode array (LED-array), optical system aberrations and use of partial coherent sources are common issues which have been addressed with calibration algorithms. However, physical interpretation of how these factors influence the algorithm and cause mismatches between theory and practice has had little attention so far. This work provides a discussion based on simulation results on the effect of the partial coherence of the source. From obtained results, an optimal set of LEDs for data acquisition is described which avoids degeneracy caused by partial coherence and is based on the numerical aperture (NA) of the objective and source parameters such as bandwidth and size.
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Fourier Ptychography is a computational imaging technique able to decouple high resolution from wide field of view, bypassing the diffraction limit of the microscope. Since it does not rely on high precision mechanics or fluorescent imaging, it is of practical interest for implementation in low scale devices. Despite its gains, realizing a functional low-cost setup working at the theoretical limits is challenging due to many factors causing discrepancies between theory and practice. Misalignment of the light emitting diode array (LED-array), optical system aberrations and use of partial coherent sources are common issues which have been addressed with calibration algorithms. However, physical interpretation of how these factors influence the algorithm and cause mismatches between theory and practice has had little attention so far. This work provides a discussion based on simulation results on the effect of the partial coherence of the source. From obtained results, an optimal set of LEDs for data acquisition is described which avoids degeneracy caused by partial coherence and is based on the numerical aperture (NA) of the objective and source parameters such as bandwidth and size.
Journal article
(2020)
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Vitalii Bezzubik, Nikolai Belashenkov, Oleg Soloviev, Vladimir Vasilyev, Gleb Vdovin
In this Letter, we report on an algorithm and its implementation to reconstruct the wavefront as a continuous function from a bitmap image of the Hartmann–Shack pattern. The approach works with arbitrary raster geometry and does not require explicit spot definition and phase unwrapping. The system matrix, defining the coefficients of wavefront decomposition in the system of basis functions, is obtained as a result of a series of convolutions and thresholding operations on the reference and sample images.
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In this Letter, we report on an algorithm and its implementation to reconstruct the wavefront as a continuous function from a bitmap image of the Hartmann–Shack pattern. The approach works with arbitrary raster geometry and does not require explicit spot definition and phase unwrapping. The system matrix, defining the coefficients of wavefront decomposition in the system of basis functions, is obtained as a result of a series of convolutions and thresholding operations on the reference and sample images.
Journal article
(2020)
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Paolo Pozzi, Carlas Smith, Elizabeth Carroll, Dean Wilding, Oleg Soloviev, Martin Booth, Gleb Vdovin, Michel Verhaegen
Inhomogeneities in the refractive index of a biological microscopy sample can introduce phase aberrations, severely impairing the quality of images. Adaptive optics can be employed to correct for phase aberrations and improve image quality. However, conventional adaptive optics can only correct a single phase aberration for the whole field of view (isoplanatic correction) while, due to the highly heterogeneous nature of biological tissues, the sample induced aberrations in microscopy often vary throughout the field of view (anisoplanatic aberration), limiting significantly the effectiveness of adaptive optics. This paper reports on a new approach for aberration correction in laser scanning confocal microscopy, in which a spatial light modulator is used to generate multiple excitation points in the sample to simultaneously scan different portions of the field of view with completely independent correction, achieving anisoplanatic compensation of sample induced aberrations, in a significantly shorter time compared to sequential isoplanatic correction of multiple image subregions. The method was tested in whole Drosophila brains and in larval Zebrafish, each showing a dramatic improvement in resolution and sharpness when compared to conventional isoplanatic adaptive optics.
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Inhomogeneities in the refractive index of a biological microscopy sample can introduce phase aberrations, severely impairing the quality of images. Adaptive optics can be employed to correct for phase aberrations and improve image quality. However, conventional adaptive optics can only correct a single phase aberration for the whole field of view (isoplanatic correction) while, due to the highly heterogeneous nature of biological tissues, the sample induced aberrations in microscopy often vary throughout the field of view (anisoplanatic aberration), limiting significantly the effectiveness of adaptive optics. This paper reports on a new approach for aberration correction in laser scanning confocal microscopy, in which a spatial light modulator is used to generate multiple excitation points in the sample to simultaneously scan different portions of the field of view with completely independent correction, achieving anisoplanatic compensation of sample induced aberrations, in a significantly shorter time compared to sequential isoplanatic correction of multiple image subregions. The method was tested in whole Drosophila brains and in larval Zebrafish, each showing a dramatic improvement in resolution and sharpness when compared to conventional isoplanatic adaptive optics.
We consider the extension of the traditional projection-based phase retrieval algorithms by increasing the problem dimensionality and introducing novel projection operators. The approach is demonstrated on an example of phase retrieval for the high-NA case.
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We consider the extension of the traditional projection-based phase retrieval algorithms by increasing the problem dimensionality and introducing novel projection operators. The approach is demonstrated on an example of phase retrieval for the high-NA case.