The Wharton’s jelly, a mucoid connective tissue of the umbilical cord, is promising for regenerative medicine applications. However it is relatively new and poorly documented especially from a mechanical point of view. To help filling the gap in the literature lack of data, this study seeks to address the Wharton’s jelly damage behavior by providing first key results through an efficient analytical approach. The tensile and damage behavior of Wharton’s jelly membranes is studied using tensile tests conducted up to failure under close physiological conditions. The Wharton’s jelly mechanical response has been characterized using an hyperelastic constitutive model based on the Ogden formulation, enhanced with continuum damage mechanics to capture analytically the damage behavior. To support the mechanical analysis, optical coherence tomography was used to assess the stress-free microstructural arrangement of the collagen fibers, revealing a transversely isotropic architecture. This qualitative insight into the internal structure enriched the interpretation of the mechanical behavior. Overall, this analytical study enabled the identification of a comprehensive set of material parameters characterizing both elastic and damage responses. Pearson correlation matrices were used to reveal meaningful relationships between parameters, potential predictive descriptors, and model’s limitations. These findings provide a solid foundation for future modeling developments through numerical simulation and offer new outlooks for surgery and dressing applications.
{"title":"Macro-scale damage characterization of Wharton’s jelly membrane undergoing tension","authors":"Alexis Da Rocha , Anaïs Lavrand , Cristina Cavinato , Cédric Laurent , Cédric Mauprivez , Halima Kerdjoudj , Chrystelle Po , Adrien Baldit","doi":"10.1016/j.jmbbm.2025.107236","DOIUrl":"10.1016/j.jmbbm.2025.107236","url":null,"abstract":"<div><div>The Wharton’s jelly, a mucoid connective tissue of the umbilical cord, is promising for regenerative medicine applications. However it is relatively new and poorly documented especially from a mechanical point of view. To help filling the gap in the literature lack of data, this study seeks to address the Wharton’s jelly damage behavior by providing first key results through an efficient analytical approach. The tensile and damage behavior of Wharton’s jelly membranes is studied using tensile tests conducted up to failure under close physiological conditions. The Wharton’s jelly mechanical response has been characterized using an hyperelastic constitutive model based on the Ogden formulation, enhanced with continuum damage mechanics to capture analytically the damage behavior. To support the mechanical analysis, optical coherence tomography was used to assess the stress-free microstructural arrangement of the collagen fibers, revealing a transversely isotropic architecture. This qualitative insight into the internal structure enriched the interpretation of the mechanical behavior. Overall, this analytical study enabled the identification of a comprehensive set of material parameters characterizing both elastic and damage responses. Pearson correlation matrices were used to reveal meaningful relationships between parameters, potential predictive descriptors, and model’s limitations. These findings provide a solid foundation for future modeling developments through numerical simulation and offer new outlooks for surgery and dressing applications.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"174 ","pages":"Article 107236"},"PeriodicalIF":3.5,"publicationDate":"2025-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145442254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nickel-titanium (NiTi) endodontic instruments, also known as files, are widely used in root canal treatments due to their superelastic and shape memory properties. However, their unpredictable failure remains a major concern in clinical practice. In this study, acoustic emission (AE) monitoring is used to assess tool wear and detect early-stage damage in real-time. By segmenting the AE frequency spectrum into four bands corresponding to the sensor's sensitivity range (195–742 kHz), high- and low-frequency acoustic energy indicators are defined. The ratio of high-to low-frequency acoustic energy—termed AEDI—is proposed as a damage indicator associated with the initiation and propagation of microcracks. Its evolution during sequential blocks of use is analyzed for about ten instruments. In parallel, the number of acoustic events and the maximum penetration force are recorded and analyzed. The analysis reveals mechanical and acoustic instabilities that can inform the development of early damage detection criteria. Two predictive approaches are proposed: one based on the cumulative high-frequency AE energy (an energy threshold criterion), and another based on the progressive amplitude and recurrence of mechanical and acoustic instabilities (an incremental criterion). The cumulative AEDI-based criterion considers the total energy of high-frequency signals exceeding a defined threshold, and generally predicts damage later, after an average of 5.81 blocks (SD = 0.92). In contrast, the incremental criterion, which is based on changes in maximum force drop and AEDI increases observed at the end of each block, provides earlier warnings, with an average of 3.75 blocks (SD = 1.16). These findings lay the groundwork for the development of a real-time predictive maintenance method for NiTi endodontic files, aimed at enhancing procedural safety and instrument reliability.
{"title":"Health monitoring of NiTi endodontic instruments using acoustic Emission: Spectral indicators for predictive damage detection","authors":"Jeanne Davril , Romain Hocquel , Marin Vincent , Andrea Cappella , Rémy Balthazard , Éric Mortier , Adrien Baldit , Rachid Rahouadj","doi":"10.1016/j.jmbbm.2025.107246","DOIUrl":"10.1016/j.jmbbm.2025.107246","url":null,"abstract":"<div><div>Nickel-titanium (NiTi) endodontic instruments, also known as files, are widely used in root canal treatments due to their superelastic and shape memory properties. However, their unpredictable failure remains a major concern in clinical practice. In this study, acoustic emission (AE) monitoring is used to assess tool wear and detect early-stage damage in real-time. By segmenting the AE frequency spectrum into four bands corresponding to the sensor's sensitivity range (195–742 kHz), high- and low-frequency acoustic energy indicators are defined. The ratio of high-to low-frequency acoustic energy—termed AEDI—is proposed as a damage indicator associated with the initiation and propagation of microcracks. Its evolution during sequential blocks of use is analyzed for about ten instruments. In parallel, the number of acoustic events and the maximum penetration force are recorded and analyzed. The analysis reveals mechanical and acoustic instabilities that can inform the development of early damage detection criteria. Two predictive approaches are proposed: one based on the cumulative high-frequency AE energy (an energy threshold criterion), and another based on the progressive amplitude and recurrence of mechanical and acoustic instabilities (an incremental criterion). The cumulative AEDI-based criterion considers the total energy of high-frequency signals exceeding a defined threshold, and generally predicts damage later, after an average of 5.81 blocks (SD = 0.92). In contrast, the incremental criterion, which is based on changes in maximum force drop and AEDI increases observed at the end of each block, provides earlier warnings, with an average of 3.75 blocks (SD = 1.16). These findings lay the groundwork for the development of a real-time predictive maintenance method for NiTi endodontic files, aimed at enhancing procedural safety and instrument reliability.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107246"},"PeriodicalIF":3.5,"publicationDate":"2025-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145403505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-25DOI: 10.1016/j.jmbbm.2025.107251
Bo E. Seiferheld , Kenneth K. Jensen , Jens B. Frøkjær , Rami K. Korhonen , Petri Tanska , Michael S. Andersen
Cartilage mechanical properties have been suggested to be more effective biomarkers for early-stage osteoarthritis (OA) than conventional clinical pain and image feature detection, when compared with OA grading methods. However, limited research exists evaluating the feasibility of alternative methods, such as magnetic resonance imaging (MRI) techniques, to determine biomechanical properties. Therefore, this study aimed to evaluate the feasibility of clinical MRI for non-invasive evaluation of cartilage creep behaviour and biomechanical properties. Bovine cartilage samples (n = 12, diameter = 6 mm) were loaded at 0.25 MPa/s until reaching 1 MPa, then held under constant stress for 1 h using a counterbalanced study design with two different configurations. The first configuration used a custom-made, hydraulic-based MRI-compatible device to apply the load to the sample. During loading, 2D proton density-weighted fast spin echo MR images with fat suppression (CHESS method) were captured every minute. The second configuration used a universal testing machine as a ground truth (GT) reference. Time-dependent creep deformation was assessed in both configurations, and the instantaneous and equilibrium moduli were calculated at 1 min and at the end of the creep test, respectively. In addition, sample-specific fibril-reinforced poroelastic (FRPE) material parameters were estimated for both configurations using inverse finite element analysis of the measured creep data. The FRPE model successfully simulated experimental data, with mean R2 values of 0.77 [95 % CI: 0.61, 0.92] for MRI and 0.98 [95 % CI: 0.95, 0.99] for GT. Results showed comparable deformation trajectories with no significant differences in the FRPE material properties between the configurations (i.e., ). Only the mean instantaneous modulus at 1 min of creep was higher (p < 0.001) with MRI 4.5 [95 % CI: 2.9, 6.1] MPa compared to GT 2.9 [95 % CI: 2.3, 3.5] MPa. These findings demonstrate that MRI can capture cartilage creep deformation and estimate biomechanical properties with reasonable accuracy in an ex vivo setting. This advocates towards further development of the workflow for creep compression experiments in vivo. Yet, the workflow requires load-controlled relaxation and considerations of 3D contact mechanics of the human knee. While this work does not yet establish clear clinical applicability, it represents important evidence for non-invasive quantification of cartilage biomechanics. It is conceivable that our advancements may contribute to subject-specific estimation of inherent biomechanical tissue properties in the future.
{"title":"Magnetic resonance imaging provides accurate measures of cartilage creep and biomechanical tissue properties: Ex vivo comparison to ground truth mechanical testing","authors":"Bo E. Seiferheld , Kenneth K. Jensen , Jens B. Frøkjær , Rami K. Korhonen , Petri Tanska , Michael S. Andersen","doi":"10.1016/j.jmbbm.2025.107251","DOIUrl":"10.1016/j.jmbbm.2025.107251","url":null,"abstract":"<div><div>Cartilage mechanical properties have been suggested to be more effective biomarkers for early-stage osteoarthritis (OA) than conventional clinical pain and image feature detection, when compared with OA grading methods. However, limited research exists evaluating the feasibility of alternative methods, such as magnetic resonance imaging (MRI) techniques, to determine biomechanical properties. Therefore, this study aimed to evaluate the feasibility of clinical MRI for non-invasive evaluation of cartilage creep behaviour and biomechanical properties. Bovine cartilage samples (<em>n</em> = 12, diameter = 6 mm) were loaded at 0.25 MPa/s until reaching 1 MPa, then held under constant stress for 1 h using a counterbalanced study design with two different configurations. The first configuration used a custom-made, hydraulic-based MRI-compatible device to apply the load to the sample. During loading, 2D proton density-weighted fast spin echo MR images with fat suppression (CHESS method) were captured every minute. The second configuration used a universal testing machine as a ground truth (GT) reference. Time-dependent creep deformation was assessed in both configurations, and the instantaneous and equilibrium moduli were calculated at 1 min and at the end of the creep test, respectively. In addition, sample-specific fibril-reinforced poroelastic (FRPE) material parameters were estimated for both configurations using inverse finite element analysis of the measured creep data. The FRPE model successfully simulated experimental data, with mean R<sup>2</sup> values of 0.77 [95 % CI: 0.61, 0.92] for MRI and 0.98 [95 % CI: 0.95, 0.99] for GT. Results showed comparable deformation trajectories with no significant differences in the FRPE material properties between the configurations (i.e., <span><math><mrow><msubsup><mi>E</mi><mi>f</mi><mn>0</mn></msubsup><mo>,</mo><msubsup><mi>E</mi><mi>f</mi><mi>ε</mi></msubsup><mo>,</mo><msub><mi>E</mi><mtext>nf</mtext></msub><mo>,</mo><msub><mi>k</mi><mn>0</mn></msub><mo>,</mo><mi>M</mi></mrow></math></span>). Only the mean instantaneous modulus at 1 min of creep was higher (<em>p</em> < 0.001) with MRI 4.5 [95 % CI: 2.9, 6.1] MPa compared to GT 2.9 [95 % CI: 2.3, 3.5] MPa. These findings demonstrate that MRI can capture cartilage creep deformation and estimate biomechanical properties with reasonable accuracy in an <em>ex vivo</em> setting. This advocates towards further development of the workflow for creep compression experiments <em>in vivo</em>. Yet, the workflow requires load-controlled relaxation and considerations of 3D contact mechanics of the human knee. While this work does not yet establish clear clinical applicability, it represents important evidence for non-invasive quantification of cartilage biomechanics. It is conceivable that our advancements may contribute to subject-specific estimation of inherent biomechanical tissue properties in the future.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107251"},"PeriodicalIF":3.5,"publicationDate":"2025-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145412923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-25DOI: 10.1016/j.jmbbm.2025.107238
Allison Clement , Azin Mirzajavadkhan , Remy Benais , Saeid Samiezadeh , Stewart McLachlin , Michael Hardisty , Cari M. Whyne
Bone tissue failure consists of damage, defined as a loss of material integrity or stiffness, and fracture, describing the separation of the material. Bone tissue damage plays a role in regulating bone turnover. Bone fracture can lead to loss of mobility, pain and the need for stabilization procedures. Micro finite element (μFE) modeling has been used as a non-destructive tool to investigate stiffness, strength, post-yield behavior, damage and fracture in bone. Previous studies have utilized elastic-plastic mechanics and continuum damage mechanics (with or without element deletion) to model damage or a fracture mechanics approach with an existing crack to model fracture. This work combines continuum damage mechanics with cohesive zone modeling to simulate damage initiation, crack formation, and fracture propagation in rodent vertebrae. Voxel-based μFE models were generated from micro computed tomography (μCT) images of the 2nd Lumbar (L2) vertebrae in five rat spinal motion segments (L1-L3). A μCT compatible loading device was used to apply axial compressive loading to failure under a sequential loading/imaging protocol. Displacement boundary conditions for the μFE models were derived from a surface-based registration algorithm using the loaded and unloaded μCT scans. Zero-thickness cohesive elements were inserted in a region of interest representing ¼ of each full model. Damage was modeled within the cohesive elements as a smooth decrease in stiffness and combined with a continuum damage model to represent a decrease of stiffness due to material failure. At the onset of fracture, the fully degraded cohesive elements were deleted allowing adjacent surfaces to separate. Damage site locations (vertebral body or posterior elements) and patterns of fracture (crack formation leading to separation or compaction) in the μFE models matched those in the post-failure μCT images. The proposed approach, while computationally expensive, enables modeling of post-failure behavior of vertebral bone, allowing the identification of damage initiation sites, fracture propagation and contact between failed trabeculae.
{"title":"Micro finite element analysis of vertebrae using zero-thickness cohesive elements represents post-failure fracture patterns","authors":"Allison Clement , Azin Mirzajavadkhan , Remy Benais , Saeid Samiezadeh , Stewart McLachlin , Michael Hardisty , Cari M. Whyne","doi":"10.1016/j.jmbbm.2025.107238","DOIUrl":"10.1016/j.jmbbm.2025.107238","url":null,"abstract":"<div><div>Bone tissue failure consists of damage, defined as a loss of material integrity or stiffness, and fracture, describing the separation of the material. Bone tissue damage plays a role in regulating bone turnover. Bone fracture can lead to loss of mobility, pain and the need for stabilization procedures. Micro finite element (μFE) modeling has been used as a non-destructive tool to investigate stiffness, strength, post-yield behavior, damage and fracture in bone. Previous studies have utilized elastic-plastic mechanics and continuum damage mechanics (with or without element deletion) to model damage or a fracture mechanics approach with an existing crack to model fracture. This work combines continuum damage mechanics with cohesive zone modeling to simulate damage initiation, crack formation, and fracture propagation in rodent vertebrae. Voxel-based μFE models were generated from micro computed tomography (μCT) images of the 2nd Lumbar (L2) vertebrae in five rat spinal motion segments (L1-L3). A μCT compatible loading device was used to apply axial compressive loading to failure under a sequential loading/imaging protocol. Displacement boundary conditions for the μFE models were derived from a surface-based registration algorithm using the loaded and unloaded μCT scans. Zero-thickness cohesive elements were inserted in a region of interest representing ¼ of each full model. Damage was modeled within the cohesive elements as a smooth decrease in stiffness and combined with a continuum damage model to represent a decrease of stiffness due to material failure. At the onset of fracture, the fully degraded cohesive elements were deleted allowing adjacent surfaces to separate. Damage site locations (vertebral body or posterior elements) and patterns of fracture (crack formation leading to separation or compaction) in the μFE models matched those in the post-failure μCT images. The proposed approach, while computationally expensive, enables modeling of post-failure behavior of vertebral bone, allowing the identification of damage initiation sites, fracture propagation and contact between failed trabeculae.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107238"},"PeriodicalIF":3.5,"publicationDate":"2025-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145412921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-25DOI: 10.1016/j.jmbbm.2025.107245
Mahzad Sadati , Michael Baggaley , Kavya Weerasinghe , Karyne N. Rabey , Michael R. Doschak , Lindsey Westover , Dan L. Romanyk
The present study aimed to develop and validate a transversely isotropic finite element (FE) model of the cranial suture that predicts suture mechanics, validated using ex-vivo data from the swine internasal suture. A 2D displacement-controlled FE model of the bone-suture-bone complex was constructed using microcomputed tomography () images, with a uniform cross-section and boundary conditions replicating experimental tensile tests. Suture geometry was modeled at three evenly spaced positions to explore how material anisotropy captures regional mechanical variation. Collagen fiber orientation was quantified from histological sections based on fiber angles relative to the suture-bone interface. Transversely isotropic material parameters were identified and optimized to match ex-vivo experimental outcomes using response surface methodology (RSM) with a five-level central composite design. Nodal forces at the displaced bone face were used from FE simulations to compare with experimental force-displacement measurements. Analysis of variance revealed that shear modulus , and Young's moduli , and significantly influenced force response (p < 0.05). Transitioning from isotropic to transversely isotropic material behavior led to a reduction in strain energy within the suture. Regional variation in suture interdigitation and thickness affected fiber alignment, enabling greater deformation and influencing mechanical behavior. The presented study developed a 2D FE model that incorporated transversely isotropic material properties to better predict the mechanical behavior of the region-specific internasal suture geometry. By incorporating histology-based collagen fiber orientation and optimizing transversely isotropic material properties using experimental data, the model captured region-specific mechanical responses, offering new insight into the structural role of anisotropy in cranial suture mechanics.
{"title":"Modeling and optimization of cranial suture anisotropic material properties using a response surface methodology","authors":"Mahzad Sadati , Michael Baggaley , Kavya Weerasinghe , Karyne N. Rabey , Michael R. Doschak , Lindsey Westover , Dan L. Romanyk","doi":"10.1016/j.jmbbm.2025.107245","DOIUrl":"10.1016/j.jmbbm.2025.107245","url":null,"abstract":"<div><div>The present study aimed to develop and validate a transversely isotropic finite element (FE) model of the cranial suture that predicts suture mechanics, validated using ex-vivo data from the swine internasal suture. A 2D displacement-controlled FE model of the bone-suture-bone complex was constructed using microcomputed tomography (<span><math><mrow><mi>μ</mi><mi>C</mi><mi>T</mi></mrow></math></span>) images, with a uniform cross-section and boundary conditions replicating experimental tensile tests. Suture geometry was modeled at three evenly spaced positions to explore how material anisotropy captures regional mechanical variation. Collagen fiber orientation was quantified from histological sections based on fiber angles relative to the suture-bone interface. Transversely isotropic material parameters were identified and optimized to match ex-vivo experimental outcomes using response surface methodology (RSM) with a five-level central composite design. Nodal forces at the displaced bone face were used from FE simulations to compare with experimental force-displacement measurements. Analysis of variance revealed that shear modulus <span><math><mrow><mo>(</mo><msub><mi>G</mi><mrow><mi>x</mi><mi>y</mi></mrow></msub><mo>)</mo></mrow></math></span>, and Young's moduli <span><math><mrow><mo>(</mo><msub><mi>E</mi><mi>y</mi></msub></mrow></math></span>, and <span><math><mrow><msub><mi>E</mi><mi>x</mi></msub><mo>)</mo></mrow></math></span> significantly influenced force response (p < 0.05). Transitioning from isotropic to transversely isotropic material behavior led to a reduction in strain energy within the suture. Regional variation in suture interdigitation and thickness affected fiber alignment, enabling greater deformation and influencing mechanical behavior. The presented study developed a 2D FE model that incorporated transversely isotropic material properties to better predict the mechanical behavior of the region-specific internasal suture geometry. By incorporating histology-based collagen fiber orientation and optimizing transversely isotropic material properties using experimental data, the model captured region-specific mechanical responses, offering new insight into the structural role of anisotropy in cranial suture mechanics.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107245"},"PeriodicalIF":3.5,"publicationDate":"2025-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145412920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-24DOI: 10.1016/j.jmbbm.2025.107250
Ahmed A. Alshareef , J. Sebastian Giudice , Daniel F. Shedd , Yuan-Chiao Lu , Curtis L. Johnson , Dzung L. Pham , Matthew B. Panzer
Rapid head motion causes the brain to deform, which may lead to acute and chronic consequences to normal brain health and function. Since the risk and severity of brain injury correlates with brain strain, computational and physical models of the brain response to impact are commonly used to assess risk and evaluate safety devices in silico. Most physical head surrogates that are used for equipment evaluation, however, are simplified and lack internal measures of brain deformation, relying instead on the interpretation of the resulting head kinematics to predict injury. Developing a more biofidelic physical brain surrogate to improve brain injury risk assessments requires the use of experimental brain motion data. Two techniques, sonomicrometry and tagged magnetic resonance imaging (tMRI), have been independently developed to characterize the in situ and in vivo brain response. Combining data acquired from both techniques can leverage the advantages of each method while alleviating the limitations. The objectives of this study were to create a head surrogate with realistic intracranial geometry and brain simulant for use in multimodal brain deformation experiments. Six gel simulants were tested using shear rheometry, with Sylgard 527 chosen as the best simulant for this study. The headform was created using the average geometry from an MRI template of 20 healthy volunteers, and was tested under non-injurious loading conditions using tMRI and sonomicrometry. The prototype headform showed good contrast in T1-weighted MRI and captured similar strain patterns when compared to the in vivo human response, although maximum principal strains (MPS) were approximately double what is measured in vivo. The two techniques showed good correspondence in brain motion response with trade-offs in temporal resolution and measurement density. Both techniques also showed similar displacement and strain magnitudes with a finite element simulation of the headform. Future studies will focus on including a more realistic sliding condition between skull and brain, as well as optimizing the material properties to better match the in vivo and in situ data.
{"title":"Multimodal characterization of intracranial biomechanics in a 3D biofidelic head surrogate","authors":"Ahmed A. Alshareef , J. Sebastian Giudice , Daniel F. Shedd , Yuan-Chiao Lu , Curtis L. Johnson , Dzung L. Pham , Matthew B. Panzer","doi":"10.1016/j.jmbbm.2025.107250","DOIUrl":"10.1016/j.jmbbm.2025.107250","url":null,"abstract":"<div><div>Rapid head motion causes the brain to deform, which may lead to acute and chronic consequences to normal brain health and function. Since the risk and severity of brain injury correlates with brain strain, computational and physical models of the brain response to impact are commonly used to assess risk and evaluate safety devices <em>in silico</em>. Most physical head surrogates that are used for equipment evaluation, however, are simplified and lack internal measures of brain deformation, relying instead on the interpretation of the resulting head kinematics to predict injury. Developing a more biofidelic physical brain surrogate to improve brain injury risk assessments requires the use of experimental brain motion data. Two techniques, sonomicrometry and tagged magnetic resonance imaging (tMRI), have been independently developed to characterize the <em>in situ</em> and <em>in vivo</em> brain response. Combining data acquired from both techniques can leverage the advantages of each method while alleviating the limitations. The objectives of this study were to create a head surrogate with realistic intracranial geometry and brain simulant for use in multimodal brain deformation experiments. Six gel simulants were tested using shear rheometry, with Sylgard 527 chosen as the best simulant for this study. The headform was created using the average geometry from an MRI template of 20 healthy volunteers, and was tested under non-injurious loading conditions using tMRI and sonomicrometry. The prototype headform showed good contrast in T1-weighted MRI and captured similar strain patterns when compared to the <em>in vivo</em> human response, although maximum principal strains (MPS) were approximately double what is measured <em>in vivo</em>. The two techniques showed good correspondence in brain motion response with trade-offs in temporal resolution and measurement density. Both techniques also showed similar displacement and strain magnitudes with a finite element simulation of the headform. Future studies will focus on including a more realistic sliding condition between skull and brain, as well as optimizing the material properties to better match the <em>in vivo</em> and <em>in situ</em> data.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107250"},"PeriodicalIF":3.5,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145395920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-24DOI: 10.1016/j.jmbbm.2025.107237
Yosef Wakjira , Arturo Cioni , Hirpa G. Lemu , Hanne R. Hagland
This study investigates the mechanical and biological properties of biomimetic Triply Periodic Minimal Surface (TPMS) based scaffolds Gyroid, Split P, and Neovius fabricated using the stereolithography process of additive manufacturing technique and biocompatible material for bone tissue engineering applications. Scaffolds were printed in both uniform and graded configurations at a fixed 60 % relative density and dimensions of 20 mm in diameter × 2 mm thickness. Compression test, energy absorption capacity and cell proliferation and attachment of the TPMS, were tested and analysed. The test results revealed that graded structures, particularly Split P and Neovius, demonstrated superior compressive strength, specific energy absorption, and elasticity compared to their uniform counterparts, indicating their suitability for load-bearing applications. Optical and Scanning Electron Microscopy analyses confirmed the consistency and accuracy of the 3D printed material distribution and structural performance. Biological evaluation using the A549 cell line demonstrated statistically significant differences in cell viability (p < 0.001) across scaffold types over 24, 48, and 72 h. Because A549 is a non-osteogenic screening model, these findings should be interpreted as preliminary cytocompatibility and attachment outcomes rather than osteogenic performance. This geometry-focused, material-agnostic study uses a dimensionally accurate SLA resin to isolate the effects of uniform vs. graded TPMS architectures on mechanics and early cell compatibility, establishing a controlled baseline to inform future work with bone-relevant cells and bioactive ceramics/metals. The Gyroid scaffold supported the highest early-stage proliferation, attributed to its continuous and highly interconnected pore geometry. These results emphasize the importance of geometry and grading in achieving a balance between mechanical integrity and biological compatibility. The potential of graded TPMS scaffolds to meet the complex demands of bone regeneration, providing a customizable platform for the development of next-generation orthopedic implants is suggested.
{"title":"Mechanical and cell attachment evaluation of additively manufactured biomimetic architected scaffolds for tissue engineering","authors":"Yosef Wakjira , Arturo Cioni , Hirpa G. Lemu , Hanne R. Hagland","doi":"10.1016/j.jmbbm.2025.107237","DOIUrl":"10.1016/j.jmbbm.2025.107237","url":null,"abstract":"<div><div>This study investigates the mechanical and biological properties of biomimetic Triply Periodic Minimal Surface (TPMS) based scaffolds Gyroid, Split P, and Neovius fabricated using the stereolithography process of additive manufacturing technique and biocompatible material for bone tissue engineering applications. Scaffolds were printed in both uniform and graded configurations at a fixed 60 % relative density and dimensions of 20 mm in diameter × 2 mm thickness. Compression test, energy absorption capacity and cell proliferation and attachment of the TPMS, were tested and analysed. The test results revealed that graded structures, particularly Split P and Neovius, demonstrated superior compressive strength, specific energy absorption, and elasticity compared to their uniform counterparts, indicating their suitability for load-bearing applications. Optical and Scanning Electron Microscopy analyses confirmed the consistency and accuracy of the 3D printed material distribution and structural performance. Biological evaluation using the A549 cell line demonstrated statistically significant differences in cell viability (p < 0.001) across scaffold types over 24, 48, and 72 h. Because A549 is a non-osteogenic screening model, these findings should be interpreted as preliminary cytocompatibility and attachment outcomes rather than osteogenic performance. This geometry-focused, material-agnostic study uses a dimensionally accurate SLA resin to isolate the effects of uniform vs. graded TPMS architectures on mechanics and early cell compatibility, establishing a controlled baseline to inform future work with bone-relevant cells and bioactive ceramics/metals. The Gyroid scaffold supported the highest early-stage proliferation, attributed to its continuous and highly interconnected pore geometry. These results emphasize the importance of geometry and grading in achieving a balance between mechanical integrity and biological compatibility. The potential of graded TPMS scaffolds to meet the complex demands of bone regeneration, providing a customizable platform for the development of next-generation orthopedic implants is suggested.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107237"},"PeriodicalIF":3.5,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145395858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-23DOI: 10.1016/j.jmbbm.2025.107240
Daniel Sebastia-Saez , Jinyuan Luo , Mengqi Qin , Tao Chen , Cynthia Yu-Wai-Man
This review examines the emerging role of mechanistic mathematical models based on continuum mechanics to address current challenges in glaucoma research. At present, the advent of Artificial Intelligence and data-based models have resulted in significant progress in drug candidate screening, target identification and delivery optimization for glaucoma treatment. Physics-based models on the other hand offer mechanistic insight by modelling fundamental physical knowledge. Mechanistic models, and specifically those based on continuum mechanics, have the potential to contribute to a better understanding of glaucoma through the description of intraocular fluid dynamics, mass and heat transfer, and other basic physical phenomena. So far, these models have expanded our understanding of ocular fluid dynamics, including descriptions of fluid flow profiles, within the anterior chamber of the eye under glaucomatous conditions. With the ongoing development of multiphysics modelling frameworks, there is increasing potential to apply these tools to a wide range of current challenges within the field of glaucoma. These challenges include glaucoma drainage devices, minimally invasive surgical procedures, therapeutic contact lenses, laser-based interventions like peripheral iridotomy, and the design and optimization of biodegradable drug-releasing intracameral implants, which support patient-specific strategies for glaucoma diagnosis and treatment.
{"title":"Advancing glaucoma research with multiphysics continuum mechanics modelling: Opportunities and open challenges","authors":"Daniel Sebastia-Saez , Jinyuan Luo , Mengqi Qin , Tao Chen , Cynthia Yu-Wai-Man","doi":"10.1016/j.jmbbm.2025.107240","DOIUrl":"10.1016/j.jmbbm.2025.107240","url":null,"abstract":"<div><div>This review examines the emerging role of mechanistic mathematical models based on continuum mechanics to address current challenges in glaucoma research. At present, the advent of Artificial Intelligence and data-based models have resulted in significant progress in drug candidate screening, target identification and delivery optimization for glaucoma treatment. Physics-based models on the other hand offer mechanistic insight by modelling fundamental physical knowledge. Mechanistic models, and specifically those based on continuum mechanics, have the potential to contribute to a better understanding of glaucoma through the description of intraocular fluid dynamics, mass and heat transfer, and other basic physical phenomena. So far, these models have expanded our understanding of ocular fluid dynamics, including descriptions of fluid flow profiles, within the anterior chamber of the eye under glaucomatous conditions. With the ongoing development of multiphysics modelling frameworks, there is increasing potential to apply these tools to a wide range of current challenges within the field of glaucoma. These challenges include glaucoma drainage devices, minimally invasive surgical procedures, therapeutic contact lenses, laser-based interventions like peripheral iridotomy, and the design and optimization of biodegradable drug-releasing intracameral implants, which support patient-specific strategies for glaucoma diagnosis and treatment.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107240"},"PeriodicalIF":3.5,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145395838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-23DOI: 10.1016/j.jmbbm.2025.107249
Jiayi Jiang , Xiaoyu Liu , Hailei Liu , Li Zhang , Shaohua Wu
By reducing fiber diameter to the nanoscale, the molecular orientation is enhanced as a result of electrostatic drawing, thereby endowing nanofibrous sutures with high tensile strength and favorable biodegradability. Nevertheless, conferring bio-functions through facile strategies remains a challenge. Herein, a modified electrospinning method was firstly developed to fabricate polycaprolactone (PCL) single yarn-based sutures (SYSs), which all showed nanofibrous micro-structure and highly aligned configuration. By adjusting the concentration of PCL solution and spinning time, a series of PCL SYSs with adjustable suture diameter and mechanical properties could be easily generated. As the solution concentration was raised from 6 % to 21 %, both the suture diameter and the nanofiber diameter increased substantially, ranging from approximately 273 to 640 μm and from around 417 to 1091 nm, respectively. Correspondingly, the breaking load rose to around 35 N, while the knotting load reached about 20 N. Similarly, when the spinning time was extended from 5 to 25 min, the suture diameter increased from nearly 270 to 594 μm, and both the breaking load and knotting load exhibited substantial improvements, attaining values around 43 N and 27 N, respectively. In contrast, the nanofiber diameter remained largely unchanged with spinning time, as electrospinning parameters were maintained constant. Then, a twisting post-treatment process was employed to process three strands of PCL SYSs into thread-based sutures (TSs), and it was found that the twisting degree had significant influences on the structure and mechanical properties of finally-obtained TSs. Increasing the twist degree from 3 to 7 twists/cm resulted in a reduction in the suture diameter of TSs from 455 to 363 μm and an enhancement in the ultimate stress from approximately 128 to 215 MPa, accompanied by superior knotting stability. In addition, the in vitro cell test demonstrated that the PCL nanofibrous sutures allowed the human dermal fibroblasts (HDFs) to adhere and proliferate on their surface and enabled cells to migrate along the suture longitudinal direction in a rapid manner. Furthermore, the hemolytic test proved the blood safety of PCL nanofibrous sutures, ensuring that they could be applied in clinical practice without causing complications such as inflammation or thrombosis. In all, this study proposed a simple method by combining modified electrospinning with twisting post-treatment to generate innovative PCL nanofibrous SYSs and TSs with modulated morphology, micro-structure, and performances, which showed huge potential as a promising candidate for absorbent surgical suture applications.
{"title":"A facile strategy to modulate the morphology, micro-structure, and performances of electrospun polycaprolactone nanofibrous sutures","authors":"Jiayi Jiang , Xiaoyu Liu , Hailei Liu , Li Zhang , Shaohua Wu","doi":"10.1016/j.jmbbm.2025.107249","DOIUrl":"10.1016/j.jmbbm.2025.107249","url":null,"abstract":"<div><div>By reducing fiber diameter to the nanoscale, the molecular orientation is enhanced as a result of electrostatic drawing, thereby endowing nanofibrous sutures with high tensile strength and favorable biodegradability. Nevertheless, conferring bio-functions through facile strategies remains a challenge. Herein, a modified electrospinning method was firstly developed to fabricate polycaprolactone (PCL) single yarn-based sutures (SYSs), which all showed nanofibrous micro-structure and highly aligned configuration. By adjusting the concentration of PCL solution and spinning time, a series of PCL SYSs with adjustable suture diameter and mechanical properties could be easily generated. As the solution concentration was raised from 6 % to 21 %, both the suture diameter and the nanofiber diameter increased substantially, ranging from approximately 273 to 640 μm and from around 417 to 1091 nm, respectively. Correspondingly, the breaking load rose to around 35 N, while the knotting load reached about 20 N. Similarly, when the spinning time was extended from 5 to 25 min, the suture diameter increased from nearly 270 to 594 μm, and both the breaking load and knotting load exhibited substantial improvements, attaining values around 43 N and 27 N, respectively. In contrast, the nanofiber diameter remained largely unchanged with spinning time, as electrospinning parameters were maintained constant. Then, a twisting post-treatment process was employed to process three strands of PCL SYSs into thread-based sutures (TSs), and it was found that the twisting degree had significant influences on the structure and mechanical properties of finally-obtained TSs. Increasing the twist degree from 3 to 7 twists/cm resulted in a reduction in the suture diameter of TSs from 455 to 363 μm and an enhancement in the ultimate stress from approximately 128 to 215 MPa, accompanied by superior knotting stability. In addition, the <em>in vitro</em> cell test demonstrated that the PCL nanofibrous sutures allowed the human dermal fibroblasts (HDFs) to adhere and proliferate on their surface and enabled cells to migrate along the suture longitudinal direction in a rapid manner. Furthermore, the hemolytic test proved the blood safety of PCL nanofibrous sutures, ensuring that they could be applied in clinical practice without causing complications such as inflammation or thrombosis. In all, this study proposed a simple method by combining modified electrospinning with twisting post-treatment to generate innovative PCL nanofibrous SYSs and TSs with modulated morphology, micro-structure, and performances, which showed huge potential as a promising candidate for absorbent surgical suture applications.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107249"},"PeriodicalIF":3.5,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145358661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-22DOI: 10.1016/j.jmbbm.2025.107244
Satya Pal , Thomas E. Angelini , Abir Bhattacharyya
Regulating elastic modulus of basic synthetic hydrogels, such as polyacrylamide, is crucial for their application in various fields of biotechnology. However, the measurement of elastic modulus and stress-strain response under different deformation modes is challenging in soft and fragile hydrogels. In this study, a non-contact, 2-dimensional digital image correlation (2D-DIC) technique is used to measure tensile and simple shear stress-strain responses of fully swelled polyacrylamide hydrogels at semi-dilute concentrations, over strain rates ranging between 10−3-10−1/s. The measured strain fields exhibit uniformity across all the deformation modes up to threshold strain levels. The elastic moduli were found to be strain-rate insensitive, except at small strains for 10−1/s due to strain acceleration and inertia of the specimen. The E and G determined from the initial slopes of stress-strain responses of lower strain-rate experiments followed De Genne's c9/4 power law scaling with equilibrium gel concentrations. The Poisson's ratio determined from the measured axial and lateral strains at small strains was found to closely match with the Poisson's ratio determined from E/G, indicating that the gels follow linear elasticity for nearly incompressible solids at small strains, but deviate from linear elasticity and becoming compressible at higher tensile strains leading to nonlinearity in tensile stress-strain response marked by reduction in instantaneous tensile modulus. The simple shear stress-strain response remains linear throughout. Finally, a polymer physics-based explanation connecting hydrogel concentration, mesh size and elastic moduli is proposed to explain strain-dependent evolution of stresses in semi-dilute polyacrylamide hydrogels for different deformation modes. Therefore, design of technologies using hydrogels must consider active deformation mode.
{"title":"Elastic moduli and strain-dependent lateral strain to axial strain ratio in semi-dilute polyacrylamide hydrogels","authors":"Satya Pal , Thomas E. Angelini , Abir Bhattacharyya","doi":"10.1016/j.jmbbm.2025.107244","DOIUrl":"10.1016/j.jmbbm.2025.107244","url":null,"abstract":"<div><div>Regulating elastic modulus of basic synthetic hydrogels, such as polyacrylamide, is crucial for their application in various fields of biotechnology. However, the measurement of elastic modulus and stress-strain response under different deformation modes is challenging in soft and fragile hydrogels. In this study, a non-contact, 2-dimensional digital image correlation (2D-DIC) technique is used to measure tensile and simple shear stress-strain responses of fully swelled polyacrylamide hydrogels at semi-dilute concentrations, over strain rates ranging between 10<sup>−3</sup>-10<sup>−1</sup>/s. The measured strain fields exhibit uniformity across all the deformation modes up to threshold strain levels. The elastic moduli were found to be strain-rate insensitive, except at small strains for 10<sup>−1</sup>/s due to strain acceleration and inertia of the specimen. The <em>E</em> and <em>G</em> determined from the initial slopes of stress-strain responses of lower strain-rate experiments followed De Genne's <em>c</em><sup>9/4</sup> power law scaling with equilibrium gel concentrations. The Poisson's ratio determined from the measured axial and lateral strains at small strains was found to closely match with the Poisson's ratio determined from <em>E/G</em>, indicating that the gels follow linear elasticity for nearly incompressible solids at small strains, but deviate from linear elasticity and becoming compressible at higher tensile strains leading to nonlinearity in tensile stress-strain response marked by reduction in instantaneous tensile modulus. The simple shear stress-strain response remains linear throughout. Finally, a polymer physics-based explanation connecting hydrogel concentration, mesh size and elastic moduli is proposed to explain strain-dependent evolution of stresses in semi-dilute polyacrylamide hydrogels for different deformation modes. Therefore, design of technologies using hydrogels must consider active deformation mode.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107244"},"PeriodicalIF":3.5,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145395825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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