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\n\n \n \n \n \n \n \n Quantifying Elastic Properties of Environmental Biofilms using Optical Coherence Elastography.\n \n \n \n \n\n\n \n Dieppa, E.; Schmitz, H.; Wang, Z.; Sabba, F.; Wells, G.; and Balogun, O.\n\n\n \n\n\n\n
JoVE, (205): e66118. March 2024.\n
Publisher: MyJoVE Corp\n\n
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@article{dieppa_quantifying_2024,\n\ttitle = {Quantifying {Elastic} {Properties} of {Environmental} {Biofilms} using {Optical} {Coherence} {Elastography}},\n\tissn = {1940-087X},\n\turl = {https://www.jove.com/t/66118},\n\tdoi = {10.3791/66118},\n\tabstract = {Biofilms are complex biomaterials comprising a well-organized network of microbial cells encased in self-produced extracellular polymeric substances (EPS). This paper presents a detailed account of the implementation of optical coherence elastography (OCE) measurements tailored for the elastic characterization of biofilms. OCE is a non-destructive optical technique that enables the local mapping of the microstructure, morphology, and viscoelastic properties of partially transparent soft materials with high spatial and temporal resolution. We provide a comprehensive guide detailing the essential procedures for the correct implementation of this technique, along with a methodology to estimate the bulk Young's modulus of granular biofilms from the collected measurements. These consist of the system setup, data acquisition, and postprocessing. In the discussion, we delve into the underlying physics of the sensors used in OCE and explore the fundamental limitations regarding the spatial and temporal scales of OCE measurements. We conclude with potential future directions for advancing the OCE technique to facilitate elastic measurements of environmental biofilms.},\n\tnumber = {205},\n\tjournal = {JoVE},\n\tauthor = {Dieppa, Evan and Schmitz, Hannah and Wang, Ziwei and Sabba, Fabrizio and Wells, George and Balogun, Oluwaseyi},\n\tmonth = mar,\n\tyear = {2024},\n\tnote = {Publisher: MyJoVE Corp},\n\tkeywords = {This Month in JoVE},\n\tpages = {e66118},\n}\n\n
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\n Biofilms are complex biomaterials comprising a well-organized network of microbial cells encased in self-produced extracellular polymeric substances (EPS). This paper presents a detailed account of the implementation of optical coherence elastography (OCE) measurements tailored for the elastic characterization of biofilms. OCE is a non-destructive optical technique that enables the local mapping of the microstructure, morphology, and viscoelastic properties of partially transparent soft materials with high spatial and temporal resolution. We provide a comprehensive guide detailing the essential procedures for the correct implementation of this technique, along with a methodology to estimate the bulk Young's modulus of granular biofilms from the collected measurements. These consist of the system setup, data acquisition, and postprocessing. In the discussion, we delve into the underlying physics of the sensors used in OCE and explore the fundamental limitations regarding the spatial and temporal scales of OCE measurements. We conclude with potential future directions for advancing the OCE technique to facilitate elastic measurements of environmental biofilms.\n
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\n\n \n \n \n \n \n \n Heat Transport at Silicon Grain Boundaries.\n \n \n \n \n\n\n \n Isotta, E.; Jiang, S.; Bueno-Villoro, R.; Nagahiro, R.; Maeda, K.; Mattlat, D. A.; Odufisan, A. R.; Zevalkink, A.; Shiomi, J.; Zhang, S.; Scheu, C.; Snyder, G. J.; and Balogun, O.\n\n\n \n\n\n\n
Advanced Functional Materials,2405413. July 2024.\n
Publisher: John Wiley & Sons, Ltd\n\n
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@article{isotta_heat_2024,\n\ttitle = {Heat {Transport} at {Silicon} {Grain} {Boundaries}},\n\tissn = {1616-301X},\n\turl = {https://doi.org/10.1002/adfm.202405413},\n\tdoi = {10.1002/adfm.202405413},\n\tabstract = {Abstract Engineering microstructural defects, like grain boundaries, offers superior control over transport properties in energy materials. However, technological advancement requires establishing microstructure-property relations at the micron or finer scales, where most of these defects operate. Here, the first experimental evidence of thermal resistance for individual silicon grain boundaries, estimated with a Gibbs excess approach, is provided. Coincident site lattice boundaries exhibit uniform excess thermal resistance along the same boundary, but notable variations from one boundary to another. Boundaries associated with low interface energy generally exhibit lower resistances, aligning with theoretical expectations and previous simulations, but several exceptions are observed. Transmission electron microscopy reveals that factors like interface roughness and presence of nanotwinning can significantly alter the observed resistance, which ranges from ?0 to up to ?2.3 m2K/GW. In stark contrast, significantly larger and less uniform values - from 5 to 30 m2K/GW - are found for high-angle boundaries in spark-plasma-sintered polycrystalline silicon. Further, finite element analysis suggests that boundary planes that strongly deviate from the sample vertical (beyond ?45°) can show up to 3-times larger excess resistance. Direct correlations of properties with individual defects enable the design of materials with superior thermal performance for applications in energy harvesting and heat management.},\n\turldate = {2024-07-03},\n\tjournal = {Advanced Functional Materials},\n\tauthor = {Isotta, Eleonora and Jiang, Shizhou and Bueno-Villoro, Ruben and Nagahiro, Ryohei and Maeda, Kosuke and Mattlat, Dominique Alexander and Odufisan, Alesanmi R. and Zevalkink, Alexandra and Shiomi, Junichiro and Zhang, Siyuan and Scheu, Christina and Snyder, G. Jeffrey and Balogun, Oluwaseyi},\n\tmonth = jul,\n\tyear = {2024},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {grain boundaries, coincident site lattices, multicrystalline silicon, structure-property relations, thermal conductivity imaging},\n\tpages = {2405413},\n}\n\n
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\n Abstract Engineering microstructural defects, like grain boundaries, offers superior control over transport properties in energy materials. However, technological advancement requires establishing microstructure-property relations at the micron or finer scales, where most of these defects operate. Here, the first experimental evidence of thermal resistance for individual silicon grain boundaries, estimated with a Gibbs excess approach, is provided. Coincident site lattice boundaries exhibit uniform excess thermal resistance along the same boundary, but notable variations from one boundary to another. Boundaries associated with low interface energy generally exhibit lower resistances, aligning with theoretical expectations and previous simulations, but several exceptions are observed. Transmission electron microscopy reveals that factors like interface roughness and presence of nanotwinning can significantly alter the observed resistance, which ranges from ?0 to up to ?2.3 m2K/GW. In stark contrast, significantly larger and less uniform values - from 5 to 30 m2K/GW - are found for high-angle boundaries in spark-plasma-sintered polycrystalline silicon. Further, finite element analysis suggests that boundary planes that strongly deviate from the sample vertical (beyond ?45°) can show up to 3-times larger excess resistance. Direct correlations of properties with individual defects enable the design of materials with superior thermal performance for applications in energy harvesting and heat management.\n
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\n\n \n \n \n \n \n \n Soft, 3D printed muscle ultrasound phantom with structurally tunable B-mode echo intensity.\n \n \n \n \n\n\n \n Gillespie, S. D; Collins, C. P; Perreault, E. J; Sun, C.; Balogun, O.; and Murray, W. M\n\n\n \n\n\n\n
bioRxiv,2024.11.29.625078. January 2024.\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n\n\n\n
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@article{gillespie_soft_2024,\n\ttitle = {Soft, {3D} printed muscle ultrasound phantom with structurally tunable {B}-mode echo intensity},\n\turl = {http://biorxiv.org/content/early/2024/12/03/2024.11.29.625078.abstract},\n\tdoi = {10.1101/2024.11.29.625078},\n\tabstract = {OBJECTIVES Imaging phantoms for training and validation are vital to improving the performance and adoption of ultrasound imaging modalities in clinical and pre-clinical applications, and the goal of this study was to assess the viability of 3D printed muscle ultrasound phantoms to meet this need.METHODS We used a soft stereolithography resin to 3D print phantoms that mimicked the fascicle- and perimysium-scale structure of skeletal muscle and compared the long axis B-mode imaging quality and pattern of the phantom to that of healthy, adult Biceps brachii. We used a pulse-echo, time-of-flight method to measure the acoustic impedance of the resin for comparison to skeletal muscle and common soft tissue mimicking materials. We analyzed the echo intensity (EI) of muscle images to establish a physiological range and compared the EI of different phantom designs to assess the ability to control imaging brightness through structural modification.RESULTS A linear, striated hyper-/hypo-echoic B-mode imaging pattern mimicking long axis Biceps brachii muscle images was achieved with two 3D structure paradigms, rod and honeycomb. Acoustic impedance of Elastic 50A resin is higher than skeletal muscle in bulk, but appears suitable for use in a 3D structured phantom. EI measured in the Biceps images were found to vary both within and across images with an overall mean ± SD of 87 ±13 AU. EI measured in honeycomb phantoms (55 ±15 AU) was higher than in rod phantoms (42 ±13 AU), and a latticed honeycomb further increased EI (90 ±11 AU).CONCLUSIONS This study serves as proof-of-concept for soft, 3D printed phantoms that replicate the characteristic muscle ultrasound imaging pattern with the ability to tune clinically relevant EI values via structural design.Competing Interest StatementThe authors have declared no competing interest.},\n\tjournal = {bioRxiv},\n\tauthor = {Gillespie, Samuel D and Collins, Caralyn P and Perreault, Eric J and Sun, Cheng and Balogun, Oluwaseyi and Murray, Wendy M},\n\tmonth = jan,\n\tyear = {2024},\n\tpages = {2024.11.29.625078},\n}\n\n
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\n OBJECTIVES Imaging phantoms for training and validation are vital to improving the performance and adoption of ultrasound imaging modalities in clinical and pre-clinical applications, and the goal of this study was to assess the viability of 3D printed muscle ultrasound phantoms to meet this need.METHODS We used a soft stereolithography resin to 3D print phantoms that mimicked the fascicle- and perimysium-scale structure of skeletal muscle and compared the long axis B-mode imaging quality and pattern of the phantom to that of healthy, adult Biceps brachii. We used a pulse-echo, time-of-flight method to measure the acoustic impedance of the resin for comparison to skeletal muscle and common soft tissue mimicking materials. We analyzed the echo intensity (EI) of muscle images to establish a physiological range and compared the EI of different phantom designs to assess the ability to control imaging brightness through structural modification.RESULTS A linear, striated hyper-/hypo-echoic B-mode imaging pattern mimicking long axis Biceps brachii muscle images was achieved with two 3D structure paradigms, rod and honeycomb. Acoustic impedance of Elastic 50A resin is higher than skeletal muscle in bulk, but appears suitable for use in a 3D structured phantom. EI measured in the Biceps images were found to vary both within and across images with an overall mean ± SD of 87 ±13 AU. EI measured in honeycomb phantoms (55 ±15 AU) was higher than in rod phantoms (42 ±13 AU), and a latticed honeycomb further increased EI (90 ±11 AU).CONCLUSIONS This study serves as proof-of-concept for soft, 3D printed phantoms that replicate the characteristic muscle ultrasound imaging pattern with the ability to tune clinically relevant EI values via structural design.Competing Interest StatementThe authors have declared no competing interest.\n
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\n\n \n \n \n \n \n Quantitative Measurement of Viscoelastic Properties of Soft Membranes Subjected to Finite Deformations Based on Optical Coherence Elastography.\n \n \n \n\n\n \n Balogun, O.; and Wang, Z.\n\n\n \n\n\n\n In Franck, C.; Kasza, K.; Estrada, J.; De Finis, R.; Ólafsson, G.; Gururaja, S.; Furmanski, J.; Forster, A.; Kolluru, P.; Prime, M.; Berfield, T.; and Aydiner, C., editor(s),
Challenges in Mechanics of Biological Systems and Materials, Thermomechanics and Infrared Imaging, Time Dependent Materials and Residual Stress, Volume 2, pages 15–19, Cham, 2024. Springer Nature Switzerland\n
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@inproceedings{balogun_quantitative_2024,\n\taddress = {Cham},\n\ttitle = {Quantitative {Measurement} of {Viscoelastic} {Properties} of {Soft} {Membranes} {Subjected} to {Finite} {Deformations} {Based} on {Optical} {Coherence} {Elastography}},\n\tisbn = {978-3-031-50470-9},\n\tabstract = {Glaucoma is a leading cause of irreversible blindness that affects over 60 million people worldwide. Glaucomatous eyes are associated with risk factors such as elevated intraocular pressure (IOP) and low corneal hysteresis. Reliable non-invasive measurement of IOP remains a formidable challenge that limits the accurate diagnosis of glaucoma and associated intervention therapies. This work investigates the propagation of shear-dominated elastic waves in hydrostatically inflated corneal tissue phantoms based on the optical coherence elastography (OCE) technique. Unlike previous approaches reported in the literature, we analyze the dispersion relation of guided elastic waves in the phantoms by accounting for both small amplitude viscoelastic wave propagation and finite static deformations. The analytical approach we adopted will enable the determination of the storage and loss shear moduli dependence on finite strains in the cornea that results from hydrostatic pressures. This work provides a modeling and experimental framework for accurately characterizing viscoelastic properties and the IOP of corneal tissues.},\n\tbooktitle = {Challenges in {Mechanics} of {Biological} {Systems} and {Materials}, {Thermomechanics} and {Infrared} {Imaging}, {Time} {Dependent} {Materials} and {Residual} {Stress}, {Volume} 2},\n\tpublisher = {Springer Nature Switzerland},\n\tauthor = {Balogun, O. and Wang, Z.},\n\teditor = {Franck, Christian and Kasza, Karen and Estrada, Jon and De Finis, Rosa and Ólafsson, Geir and Gururaja, Suhasini and Furmanski, Jevan and Forster, Aaron and Kolluru, Pavan and Prime, Mike and Berfield, Tom and Aydiner, Cahit},\n\tyear = {2024},\n\tpages = {15--19},\n}\n
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\n Glaucoma is a leading cause of irreversible blindness that affects over 60 million people worldwide. Glaucomatous eyes are associated with risk factors such as elevated intraocular pressure (IOP) and low corneal hysteresis. Reliable non-invasive measurement of IOP remains a formidable challenge that limits the accurate diagnosis of glaucoma and associated intervention therapies. This work investigates the propagation of shear-dominated elastic waves in hydrostatically inflated corneal tissue phantoms based on the optical coherence elastography (OCE) technique. Unlike previous approaches reported in the literature, we analyze the dispersion relation of guided elastic waves in the phantoms by accounting for both small amplitude viscoelastic wave propagation and finite static deformations. The analytical approach we adopted will enable the determination of the storage and loss shear moduli dependence on finite strains in the cornea that results from hydrostatic pressures. This work provides a modeling and experimental framework for accurately characterizing viscoelastic properties and the IOP of corneal tissues.\n
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