High-intensity focused ultrasound (HIFU) is used clinically to heat cells therapeutically or to destroy them through heat or cavitation. In homogeneous media, the highest wave amplitudes occur at a predictable focal region. However, HIFU is generally not used in the proximity of bones due to wave absorption and scattering. Ultrasound is passed through the skull in some clinical trials, but the complex geometry of the spine poses a greater targeting challenge and currently prohibits therapeutic ultrasound treatments near the vertebral column. This paper presents a comprehensive experimental study involving shadowgraphy and hydrophone measurements to determine the spatial distribution of pressure amplitudes from induced HIFU waves near vertebrae. First, a bone-like composite plate that is partially obstructing the induced waves is shown to break the conical HIFU form into two regions. Wave images are captured using pulsed laser shadowgraphy, and hydrophone measurements over the same region are compared to the shadowgraphy intensity plots to validate the procedure. Next, shadowgraphy is performed for an individual, clean, ex-vivo feline vertebra. The results indicate that shadowgraphy can be used to determine energy deposition patterns and to determine heating at a specific location. The latter is confirmed through additional temperature measurements. Overall, these laboratory experiments may help determine the efficacy of warming specific nerve cells within mammal vertebrae without causing damage to adjacent tissue.
{"title":"High-Intensity Focused Ultrasound Scattering at Mammal Vertebrae","authors":"D. Sanford, C. Schaal","doi":"10.1115/IMECE2020-24676","DOIUrl":"https://doi.org/10.1115/IMECE2020-24676","url":null,"abstract":"\u0000 High-intensity focused ultrasound (HIFU) is used clinically to heat cells therapeutically or to destroy them through heat or cavitation. In homogeneous media, the highest wave amplitudes occur at a predictable focal region. However, HIFU is generally not used in the proximity of bones due to wave absorption and scattering. Ultrasound is passed through the skull in some clinical trials, but the complex geometry of the spine poses a greater targeting challenge and currently prohibits therapeutic ultrasound treatments near the vertebral column. This paper presents a comprehensive experimental study involving shadowgraphy and hydrophone measurements to determine the spatial distribution of pressure amplitudes from induced HIFU waves near vertebrae. First, a bone-like composite plate that is partially obstructing the induced waves is shown to break the conical HIFU form into two regions. Wave images are captured using pulsed laser shadowgraphy, and hydrophone measurements over the same region are compared to the shadowgraphy intensity plots to validate the procedure. Next, shadowgraphy is performed for an individual, clean, ex-vivo feline vertebra. The results indicate that shadowgraphy can be used to determine energy deposition patterns and to determine heating at a specific location. The latter is confirmed through additional temperature measurements. Overall, these laboratory experiments may help determine the efficacy of warming specific nerve cells within mammal vertebrae without causing damage to adjacent tissue.","PeriodicalId":314012,"journal":{"name":"Volume 5: Biomedical and Biotechnology","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129686876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuyang Qian, Kaiming Yang, Yu Zhu, Wen Wang, C. Wan
A self-paced treadmill automatically adjusts speed in real-time to match the user’s walking speed, presumably leading to a more nature gait than fixed-speed treadmill. However, previous study has proven that the acceleration applied to the subjects would influence the gait stability. In order to have insights on to which extent will the accelerations affect gait stability, simulation analysis based on conceptual model has been done in the current study. This paper utilized a non-inertial frame based spring-loaded inverted pendulum model to analysis the condition of stability during continuous self-paced treadmill walking. Simulations were done for 100 continuous self-paced treadmill walking at the normal walking speed. And 10ms impulse accelerations of different magnitudes with the range of (−1g, 1g) were applied at different gait events such as toe-off, foot-flat and heel-strike. The simulation results showed that the magnitude of the accelerations had significantly influence on continuous self-paced treadmill walking and directional-dependency was also found. However, no significantly difference was found when applying the impulse acceleration at different gait events.
{"title":"The Condition of Dynamic Stability for Self-Paced Treadmill Walking Based on Inverted Pendulum Model","authors":"Yuyang Qian, Kaiming Yang, Yu Zhu, Wen Wang, C. Wan","doi":"10.1115/IMECE2020-23461","DOIUrl":"https://doi.org/10.1115/IMECE2020-23461","url":null,"abstract":"\u0000 A self-paced treadmill automatically adjusts speed in real-time to match the user’s walking speed, presumably leading to a more nature gait than fixed-speed treadmill. However, previous study has proven that the acceleration applied to the subjects would influence the gait stability. In order to have insights on to which extent will the accelerations affect gait stability, simulation analysis based on conceptual model has been done in the current study. This paper utilized a non-inertial frame based spring-loaded inverted pendulum model to analysis the condition of stability during continuous self-paced treadmill walking. Simulations were done for 100 continuous self-paced treadmill walking at the normal walking speed. And 10ms impulse accelerations of different magnitudes with the range of (−1g, 1g) were applied at different gait events such as toe-off, foot-flat and heel-strike. The simulation results showed that the magnitude of the accelerations had significantly influence on continuous self-paced treadmill walking and directional-dependency was also found. However, no significantly difference was found when applying the impulse acceleration at different gait events.","PeriodicalId":314012,"journal":{"name":"Volume 5: Biomedical and Biotechnology","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121149926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Three-dimensional (3D) porous tissue scaffolds combined with bioactive molecules and cells offer key advantages for bone repair mechanisms. A functional bone tissue scaffold should provide mechanical support with an adequate combination of porosity and permeability for nutrients, oxygen supply, waste removal, and growth factors release as well as controlled degradation. Although a vast amount of work exist to address these challenges, to the best of our knowledge, a design framework taking tissue differentiation, diffusion, and growth factor (GF) release into account in time-domain simultaneously does not exist. In this paper, we provide an initial effort to address such a need by laying down the foundations for a simulation framework incorporating these effects within a Finite Element Analysis (FEA) model in COMSOL Multiphysics® software. The effectiveness of the numerical model is demonstrated via preliminary mechano-biology analyses on a simulated 3D poroelastic bone scaffold. Initial time-dependent results demonstrate the suitability of this model for an optimization framework. More specifically, it is demonstrated that coupled Multiphysics equations of diffusion, GF release, and differentiation could provide valuable inputs for ideal bone scaffold systems for effective bone repair tasks in the future.
{"title":"Initial Study Towards the Integrated Design of Bone Scaffolds Based on Cell Diffusion, Growth Factor Release and Tissue Regeneration","authors":"M. Şahin, A. Tabak, Gullu Kiziltas Sendur","doi":"10.1115/IMECE2020-23940","DOIUrl":"https://doi.org/10.1115/IMECE2020-23940","url":null,"abstract":"\u0000 Three-dimensional (3D) porous tissue scaffolds combined with bioactive molecules and cells offer key advantages for bone repair mechanisms. A functional bone tissue scaffold should provide mechanical support with an adequate combination of porosity and permeability for nutrients, oxygen supply, waste removal, and growth factors release as well as controlled degradation. Although a vast amount of work exist to address these challenges, to the best of our knowledge, a design framework taking tissue differentiation, diffusion, and growth factor (GF) release into account in time-domain simultaneously does not exist. In this paper, we provide an initial effort to address such a need by laying down the foundations for a simulation framework incorporating these effects within a Finite Element Analysis (FEA) model in COMSOL Multiphysics® software. The effectiveness of the numerical model is demonstrated via preliminary mechano-biology analyses on a simulated 3D poroelastic bone scaffold. Initial time-dependent results demonstrate the suitability of this model for an optimization framework. More specifically, it is demonstrated that coupled Multiphysics equations of diffusion, GF release, and differentiation could provide valuable inputs for ideal bone scaffold systems for effective bone repair tasks in the future.","PeriodicalId":314012,"journal":{"name":"Volume 5: Biomedical and Biotechnology","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115172043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The mechanical and structural characteristics of aortic media have profound effects on the physiology and pathophysiology of an aorta. However, many aspects of the aortic tissue remain poorly understood, partly due to the intrinsic layered wall structure and regionally varying residual stresses. Our recent works have demonstrated that a mechanical interaction between the elastic lamina (EL) and smooth muscle layer in the aortic media can be computationally reproduced using a simplified finite element (FE) model. However, it is questionable whether the simplified FE model we created was representative of the structure of a real medial wall and its modeling technique would be applicable to develop a more sophisticated and structure-based aortic FE model. This study aimed to computationally represent EL buckling in the aortic medial ring at an unloaded state and successfully reproduced transmural variation in EL waviness across the aortic wall. We also aimed at confirming the inner and outer layers of the medial wall are subjected to compressive and tensile residual stresses, respectively, at the unloaded state, implying that the ring model will open spontaneously when it is radially cut. Moreover, the computed residual stresses were found to be within the reasonable range of the predicted values, 1–10 kPa, supporting the validity of our modeling approach. Although further study is required, the information obtained here will greatly help improve the understanding of basic aortic physiology and pathophysiology, while simultaneously providing a basis for more sophisticated computational modeling of the aorta.
{"title":"Regional and Layer Distribution of Residual Stresses in an Unloaded Aortic Medial Wall","authors":"A. Tamura, K. Matsumoto","doi":"10.1115/IMECE2020-23632","DOIUrl":"https://doi.org/10.1115/IMECE2020-23632","url":null,"abstract":"The mechanical and structural characteristics of aortic media have profound effects on the physiology and pathophysiology of an aorta. However, many aspects of the aortic tissue remain poorly understood, partly due to the intrinsic layered wall structure and regionally varying residual stresses. Our recent works have demonstrated that a mechanical interaction between the elastic lamina (EL) and smooth muscle layer in the aortic media can be computationally reproduced using a simplified finite element (FE) model. However, it is questionable whether the simplified FE model we created was representative of the structure of a real medial wall and its modeling technique would be applicable to develop a more sophisticated and structure-based aortic FE model. This study aimed to computationally represent EL buckling in the aortic medial ring at an unloaded state and successfully reproduced transmural variation in EL waviness across the aortic wall. We also aimed at confirming the inner and outer layers of the medial wall are subjected to compressive and tensile residual stresses, respectively, at the unloaded state, implying that the ring model will open spontaneously when it is radially cut. Moreover, the computed residual stresses were found to be within the reasonable range of the predicted values, 1–10 kPa, supporting the validity of our modeling approach. Although further study is required, the information obtained here will greatly help improve the understanding of basic aortic physiology and pathophysiology, while simultaneously providing a basis for more sophisticated computational modeling of the aorta.","PeriodicalId":314012,"journal":{"name":"Volume 5: Biomedical and Biotechnology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132071945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Pineda-Castillo, Jishan Luo, B. Bohnstedt, Chung-Hao Lee, Yingtao Liu
Intracranial aneurysms have the potential to be fatal; when detected, they must be treated promptly by surgical clipping or by endovascular methods. The latter, while having better long-term overall survival than the former, fail to provide complete occlusion of the aneurysm lumen, creating risks for therapy-related adverse events, such as embolic device migration or recanalization. Polyurethane shape memory polymers (SMPs) have the potential to provide patient-specific treatment to reduce rates of incomplete occlusion and mass effect. In this study, SMP matrices are infiltrated with carbon nanotubes (CNTs) to induce electrical conductivity and provide a precise triggering method for deployment of the embolic device. Through thermomechanical characterization of the composite, it was determined that CNTs play a significant role in resistivity of the SMP foam and its ultimate shape recovery properties. Cyclic mechanical testing allowed to determine that CNTs might induce polymeric matrix damage, creating the need for new approaches to CNT infiltration. The studied composite foams were able to occlude an in vitro idealized aneurysm phantom model, which allowed to conclude that the proposed CNT-infiltrated SMP foams exhibit potential as biomedical devices for endovascular therapy of intracranial aneurysms.
{"title":"Shape Memory Polymer Foam With Tunable Properties for Treatment of Intracranial Aneurysm","authors":"S. Pineda-Castillo, Jishan Luo, B. Bohnstedt, Chung-Hao Lee, Yingtao Liu","doi":"10.1115/IMECE2020-24291","DOIUrl":"https://doi.org/10.1115/IMECE2020-24291","url":null,"abstract":"\u0000 Intracranial aneurysms have the potential to be fatal; when detected, they must be treated promptly by surgical clipping or by endovascular methods. The latter, while having better long-term overall survival than the former, fail to provide complete occlusion of the aneurysm lumen, creating risks for therapy-related adverse events, such as embolic device migration or recanalization. Polyurethane shape memory polymers (SMPs) have the potential to provide patient-specific treatment to reduce rates of incomplete occlusion and mass effect. In this study, SMP matrices are infiltrated with carbon nanotubes (CNTs) to induce electrical conductivity and provide a precise triggering method for deployment of the embolic device. Through thermomechanical characterization of the composite, it was determined that CNTs play a significant role in resistivity of the SMP foam and its ultimate shape recovery properties. Cyclic mechanical testing allowed to determine that CNTs might induce polymeric matrix damage, creating the need for new approaches to CNT infiltration. The studied composite foams were able to occlude an in vitro idealized aneurysm phantom model, which allowed to conclude that the proposed CNT-infiltrated SMP foams exhibit potential as biomedical devices for endovascular therapy of intracranial aneurysms.","PeriodicalId":314012,"journal":{"name":"Volume 5: Biomedical and Biotechnology","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117217036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kavi Patel, Long Zhu, S. T. R. Gidde, Fei Ren, P. Hutapea
This study is aimed to evaluate the effects of coated surgical needles with composite polymers such as polydopamine (PDA), polytetrafluoroethylene (PTFE), and carbon. The coated needle’s lubrication properties were measured using 3 DOF force sensors and 3D robot system by the repetitive insertion in soft tissue materials. Needle durability is a measure of needle sharpness after repeated passage through high stiffness tissue materials. The composite coatings were shown to reduce the insertion force by ∼49% and retraction forces by ∼46% when tested using a bovine kidney. The surface roughness and the lateral friction force of the needle are measured using the Atomic Force Microscope (AFM). The adhesion energy of the different coating on the needle will be measured using a nano-scratch method.
{"title":"Influence of Composite Polymer Coatings on the Insertion Force of Needle-Like Structure in Soft Materials","authors":"Kavi Patel, Long Zhu, S. T. R. Gidde, Fei Ren, P. Hutapea","doi":"10.1115/IMECE2020-24341","DOIUrl":"https://doi.org/10.1115/IMECE2020-24341","url":null,"abstract":"\u0000 This study is aimed to evaluate the effects of coated surgical needles with composite polymers such as polydopamine (PDA), polytetrafluoroethylene (PTFE), and carbon. The coated needle’s lubrication properties were measured using 3 DOF force sensors and 3D robot system by the repetitive insertion in soft tissue materials. Needle durability is a measure of needle sharpness after repeated passage through high stiffness tissue materials. The composite coatings were shown to reduce the insertion force by ∼49% and retraction forces by ∼46% when tested using a bovine kidney. The surface roughness and the lateral friction force of the needle are measured using the Atomic Force Microscope (AFM). The adhesion energy of the different coating on the needle will be measured using a nano-scratch method.","PeriodicalId":314012,"journal":{"name":"Volume 5: Biomedical and Biotechnology","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116831168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Muhamed Albadawi, Yasser Abuouf, S. Ookawara, Mahmoud A. Ahmed
Atherosclerosis is a major arterial disease characterized by the thickening of the arteries’ walls. The development of stenosis at the carotid bifurcation affects the local variations in blood flow dynamic factors. The carotid artery dynamic factors: including the wall shear stress (WSS), time-averaged wall shear stress (TAWSS) and pressure gradient affect the rate of progression of the stenosis. It is essential to analyze the flow in three-dimensional reconstructed patient-specific geometries with realistic boundary conditions to estimate the blood flow dynamic factors. Hence, a three-dimensional comprehensive model is developed including the non-Newtonian blood flow under pulsatile flow conditions. The model is numerically simulated using computational fluid dynamics solvers along with the medical imaging to investigate the effect of stenosis locations on its progression. The numerically predicted blood flow dynamic factors are analyzed. It was found that the blood flow dynamic factors have the importance to influence the diagnosis and prediction of asymptomatic carotid artery stenosis progression. Based on results, the value of TAWSS at the stenosis in the stenotic Common Carotid Artery (CCA) is 46.68 Pa comparing to 19.24 Pa and 10.049 Pa in Internal Carotid Artery (ICA) and External Carotid Artery (ECA) respectively. Also, it was found that the maximum value of WSS in the healthy artery at the bifurcation with 3.829 Pa. However, in stenotic arteries the maximum value for WSS located at the stenosis throat which was found to be 102.158 Pa for CCA comparing to 46.859 Pa in ICA and 33.658 Pa in ECA.
{"title":"Influence of Carotid Artery Stenosis Location on Lesion Progression Using Computational Fluid Dynamics","authors":"Muhamed Albadawi, Yasser Abuouf, S. Ookawara, Mahmoud A. Ahmed","doi":"10.1115/IMECE2020-23451","DOIUrl":"https://doi.org/10.1115/IMECE2020-23451","url":null,"abstract":"\u0000 Atherosclerosis is a major arterial disease characterized by the thickening of the arteries’ walls. The development of stenosis at the carotid bifurcation affects the local variations in blood flow dynamic factors. The carotid artery dynamic factors: including the wall shear stress (WSS), time-averaged wall shear stress (TAWSS) and pressure gradient affect the rate of progression of the stenosis. It is essential to analyze the flow in three-dimensional reconstructed patient-specific geometries with realistic boundary conditions to estimate the blood flow dynamic factors. Hence, a three-dimensional comprehensive model is developed including the non-Newtonian blood flow under pulsatile flow conditions. The model is numerically simulated using computational fluid dynamics solvers along with the medical imaging to investigate the effect of stenosis locations on its progression. The numerically predicted blood flow dynamic factors are analyzed. It was found that the blood flow dynamic factors have the importance to influence the diagnosis and prediction of asymptomatic carotid artery stenosis progression. Based on results, the value of TAWSS at the stenosis in the stenotic Common Carotid Artery (CCA) is 46.68 Pa comparing to 19.24 Pa and 10.049 Pa in Internal Carotid Artery (ICA) and External Carotid Artery (ECA) respectively. Also, it was found that the maximum value of WSS in the healthy artery at the bifurcation with 3.829 Pa. However, in stenotic arteries the maximum value for WSS located at the stenosis throat which was found to be 102.158 Pa for CCA comparing to 46.859 Pa in ICA and 33.658 Pa in ECA.","PeriodicalId":314012,"journal":{"name":"Volume 5: Biomedical and Biotechnology","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117033322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Three-dimensional (3D) printing with high-resolution stereolithography (SLA) has grown in popularity for creating personalized medical devices. 3D printing is now starting to expand to weight-bearing components, e.g. prosthetic feet, as data on the dynamic properties impact and fatigue is published in the literature. The next step towards using 3D printing in impact applications is to assess the capability of the high-resolution SLA process to manufacture components of uniform impact resistance. Because impact testing is destructive, a surrogate measure to check a part’s viability for resisting an impact load also needs to be established. Thirteen notched Izod specimens were printed on a Form2 SLA printer using the manufacturer’s clear V4, photocurable resin. Once all the specimens were printed, washed in isopropyl alcohol, and cured with ultraviolet light, the impact resistance was quantified using a pendulum impact tester in a notched Izod configuration. Then, the hardness of the specimens was quantified using a HBW 10/250 scale. The impact resistance of the clear, SLA polymer was 0.59 ± 0.14 ft-lb/in. With an upper standard limit of 0.53 ft-lb/in, the process capability index was 0.133. Impact resistance and Brinell hardness were not correlated with a Spearman coefficient of r = −0.108, p = 0.73. Since the process capability index was less than one, 3D printing with SLA polymers is not a viable manufacturing process for creating parts of consistent impact resistance. The current technology would lead to too many rejected parts. Also, Brinell hardness and impact strength were not related. Therefore, there is no non-destructive method to spot-check these components before use.
{"title":"Manufacturing Capability Index of 3D Printing Parts for Impact Applications","authors":"A. Schmitz","doi":"10.1115/IMECE2020-23123","DOIUrl":"https://doi.org/10.1115/IMECE2020-23123","url":null,"abstract":"\u0000 Three-dimensional (3D) printing with high-resolution stereolithography (SLA) has grown in popularity for creating personalized medical devices. 3D printing is now starting to expand to weight-bearing components, e.g. prosthetic feet, as data on the dynamic properties impact and fatigue is published in the literature. The next step towards using 3D printing in impact applications is to assess the capability of the high-resolution SLA process to manufacture components of uniform impact resistance. Because impact testing is destructive, a surrogate measure to check a part’s viability for resisting an impact load also needs to be established. Thirteen notched Izod specimens were printed on a Form2 SLA printer using the manufacturer’s clear V4, photocurable resin. Once all the specimens were printed, washed in isopropyl alcohol, and cured with ultraviolet light, the impact resistance was quantified using a pendulum impact tester in a notched Izod configuration. Then, the hardness of the specimens was quantified using a HBW 10/250 scale. The impact resistance of the clear, SLA polymer was 0.59 ± 0.14 ft-lb/in. With an upper standard limit of 0.53 ft-lb/in, the process capability index was 0.133. Impact resistance and Brinell hardness were not correlated with a Spearman coefficient of r = −0.108, p = 0.73. Since the process capability index was less than one, 3D printing with SLA polymers is not a viable manufacturing process for creating parts of consistent impact resistance. The current technology would lead to too many rejected parts. Also, Brinell hardness and impact strength were not related. Therefore, there is no non-destructive method to spot-check these components before use.","PeriodicalId":314012,"journal":{"name":"Volume 5: Biomedical and Biotechnology","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122740153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sara Salazar-Salgado, F. Valencia, A. Uribe, Elizabeth Rendón-Vélez
There is a considerable amount of young adults who become amputees due to war and violence. For this population, a successful adaptation to their prosthesis depends on the socket fit, which in turn is caused by the volume change of the residual limb during the day. The literature reports several investigations on this topic, most of which use subjects walking on a treadmill to simulate their daily activity. However, this studies are focused on transtibial amputees and do not mention the relationship between this physical activity and other variables such as comfort, volume changes and gait. Therefore, the objective of this paper is to determine the effect of physical activity on the volume of the residual limb, the comfort and the symmetry of gait in traumatic transfemoral amputees. Plaster positive molds of the residual limb, the comfort perception and the gait data of five individuals were obtained at the first time of the day and after three sessions of treadmill walking of 15, 30 and 45 minutes. The positive molds of each individual were scanned and then, the volume was calculated. The gait data was acquired using a marker-based motion capture system and processed to obtain spatio-temporal, kinematic and kinetic parameters, including the Gait Deviation Index (GDI). Based on the literature, specific points of the gait data were selected and the symmetry index was obtain for each of them. A short comfort test was used after each session of treadmill walking. Data was analyzed throughout the tests within each subject. Statistical analysis was performed for the volume and the gait variables to check for statistical significance. After physical activity, a tendency towards residual limb volume decrease was found on almost all subjects, although it was not significant. The percentage of volume change obtained on almost all subjects are within the range considered “good socket fit” according to previous authors. Our results suggest that transfemoral amputees may have smaller volume changes than transtibial after treadmill walking. Significant difference was found on the symmetry index of “Swing phase” between the baseline and the 45-minute test. The values of gait symmetry on the gait parameters were consistent with previous findings regarding transfemoral amputees. The difference that arise may be due to the sample difference (cause of amputation, difference in prosthetic elements and use of walking aids). The lowest symmetry was noticed on the ankle kinematics. The comfort did not significantly change with the selected amount of physical activity. In subsequent research, it is recommended to increase the intensity or time of physical activity and/or increase the number of participants. This results can help the understanding of how the socket/residual limb interface behaves which can improve the design and prescription of prosthetic components.
{"title":"How Does Physical Activity Affect Residual Limb Volume Change, Comfort and Gait Symmetry on Traumatic Transfemoral Amputees?","authors":"Sara Salazar-Salgado, F. Valencia, A. Uribe, Elizabeth Rendón-Vélez","doi":"10.1115/IMECE2020-23418","DOIUrl":"https://doi.org/10.1115/IMECE2020-23418","url":null,"abstract":"\u0000 There is a considerable amount of young adults who become amputees due to war and violence. For this population, a successful adaptation to their prosthesis depends on the socket fit, which in turn is caused by the volume change of the residual limb during the day. The literature reports several investigations on this topic, most of which use subjects walking on a treadmill to simulate their daily activity. However, this studies are focused on transtibial amputees and do not mention the relationship between this physical activity and other variables such as comfort, volume changes and gait. Therefore, the objective of this paper is to determine the effect of physical activity on the volume of the residual limb, the comfort and the symmetry of gait in traumatic transfemoral amputees.\u0000 Plaster positive molds of the residual limb, the comfort perception and the gait data of five individuals were obtained at the first time of the day and after three sessions of treadmill walking of 15, 30 and 45 minutes. The positive molds of each individual were scanned and then, the volume was calculated. The gait data was acquired using a marker-based motion capture system and processed to obtain spatio-temporal, kinematic and kinetic parameters, including the Gait Deviation Index (GDI). Based on the literature, specific points of the gait data were selected and the symmetry index was obtain for each of them. A short comfort test was used after each session of treadmill walking. Data was analyzed throughout the tests within each subject. Statistical analysis was performed for the volume and the gait variables to check for statistical significance.\u0000 After physical activity, a tendency towards residual limb volume decrease was found on almost all subjects, although it was not significant. The percentage of volume change obtained on almost all subjects are within the range considered “good socket fit” according to previous authors. Our results suggest that transfemoral amputees may have smaller volume changes than transtibial after treadmill walking. Significant difference was found on the symmetry index of “Swing phase” between the baseline and the 45-minute test. The values of gait symmetry on the gait parameters were consistent with previous findings regarding transfemoral amputees. The difference that arise may be due to the sample difference (cause of amputation, difference in prosthetic elements and use of walking aids). The lowest symmetry was noticed on the ankle kinematics. The comfort did not significantly change with the selected amount of physical activity.\u0000 In subsequent research, it is recommended to increase the intensity or time of physical activity and/or increase the number of participants. This results can help the understanding of how the socket/residual limb interface behaves which can improve the design and prescription of prosthetic components.","PeriodicalId":314012,"journal":{"name":"Volume 5: Biomedical and Biotechnology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129290855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work deals with the stability of the dynamics of human squat exercise. This is a common exercise. The focus of this investigation is to analyze the knee angle time series and calculate the divergence for different weight added in the exercise. Experiments are conducted and motion capture used for each of the cases. Then the Lyapunov exponents of the time series of the knee joint angle are determined. Matlab software package is used for all calculations. Results are compared with data available in the literature. This work provides insight on the level of stability for added weight on the human squat exercise. This gives an insight on the level of safety of this exercise as weight is added to the human subject.
{"title":"Effect of Additional Weight on Lyapunov Exponents for Human Squat Exercise","authors":"J. Galarza, D. Caruntu","doi":"10.1115/IMECE2020-23943","DOIUrl":"https://doi.org/10.1115/IMECE2020-23943","url":null,"abstract":"\u0000 This work deals with the stability of the dynamics of human squat exercise. This is a common exercise. The focus of this investigation is to analyze the knee angle time series and calculate the divergence for different weight added in the exercise. Experiments are conducted and motion capture used for each of the cases. Then the Lyapunov exponents of the time series of the knee joint angle are determined. Matlab software package is used for all calculations. Results are compared with data available in the literature. This work provides insight on the level of stability for added weight on the human squat exercise. This gives an insight on the level of safety of this exercise as weight is added to the human subject.","PeriodicalId":314012,"journal":{"name":"Volume 5: Biomedical and Biotechnology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130487664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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