Pub Date : 2015-04-20DOI: 10.1109/ENBENG.2015.7088837
Joana Figueiredo, C. Santos, J. Moreno
Gait disorders are reported as outcome of gait parameters changed due to walking diseases. The impaired rehabilitation gait with active lower limb orthoses, mainly ankle-foot-orthoses (AFOs) and knee-ankle-foot orthoses (KAFOs), stands out due to possibility of recovery occur in daily living activities and incorporate the subject's voluntary participation. The purpose of this review is to compare the current designs and control strategies of mentioned orthoses. According to revised literature, an appropriate design should contain an articulated joint, a powered system, a control strategy (preferable impedance or myoelectric schemes) and be made of carbon-fiber. To assistance in real environment, the high-level control should integrate the online recognition of gait mode. Further, AFOs and KAFOs achieve efficiently the main goals of their use, owing essentially to an improvement of balance control during walking. Future designs should continue to be developed to turn more confident the application over activities of daily living.
{"title":"Assistance and rehabilitation of gait disorders using active lower limb orthoses","authors":"Joana Figueiredo, C. Santos, J. Moreno","doi":"10.1109/ENBENG.2015.7088837","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088837","url":null,"abstract":"Gait disorders are reported as outcome of gait parameters changed due to walking diseases. The impaired rehabilitation gait with active lower limb orthoses, mainly ankle-foot-orthoses (AFOs) and knee-ankle-foot orthoses (KAFOs), stands out due to possibility of recovery occur in daily living activities and incorporate the subject's voluntary participation. The purpose of this review is to compare the current designs and control strategies of mentioned orthoses. According to revised literature, an appropriate design should contain an articulated joint, a powered system, a control strategy (preferable impedance or myoelectric schemes) and be made of carbon-fiber. To assistance in real environment, the high-level control should integrate the online recognition of gait mode. Further, AFOs and KAFOs achieve efficiently the main goals of their use, owing essentially to an improvement of balance control during walking. Future designs should continue to be developed to turn more confident the application over activities of daily living.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129932988","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}
Pub Date : 2015-04-20DOI: 10.1109/ENBENG.2015.7088829
Lúcia F. A. Amorim, F. Sousa, J. Queiroz, C. Cruz, Â. Sousa
Summary form only given. Cervical cancer and high risk human papillomavirus (HPV) are highly associated and currently, the preventive vaccines only induce the antibody immunity. The urge to attenuate lesions and tumour progressions led to development of DNA vaccines, able to induce both humoural and cellular immune responses. Plasmid DNA (pDNA) is being widely explored as a non-viral vector due to its lack of toxicity, low cost manufacture and high expression levels. To produce an effective pDNA vaccine, a biotechnology platform is required and every single step has to be optimized in order to obtain this molecule with high purity degree, able to efficiently transfect eukaryotic cells with satisfactory expression of the target gene. Amino acid-affinity chromatography has been considered a promissory approach that selectively recognizes the biologically active pDNA topology, the supercoiled (sc) isoform. Thus, the aim of this work was to perform a screening of L-histidine-based amino acids employing the surface plasmon resonance (SPR) technique in order to modify a monolithic support with the suitable ligand for sc pDNA purification. Several experiments were performed with three plasmids of different sizes (6.05, 8.70 and 14 Kbp) and different isoforms (open circular, sc and linear), separately. The SPR results revealed that the overall affinity of plasmids to L-histidine-based ligands was high (KD >10-8 M) and the highest affinity was found for HPV-16 E6/E7. Therefore, L-histidine and 1-benzyl-L-histidine ligands were immobilized on epoxy monoliths and several chromatographic studies were accomplished with the aforementioned samples. In general, the sc isoform developed strong interactions with the modified supports and the separation of plasmid isoforms was achieved by decreasing the ammonium sulfate concentration. Lower salt content was required in the 1-benzyl-L-histidine monolith because of stronger interactions promoted with pDNA. The separation of plasmid isoforms remained unchanged by flow rate variations. The breakthrough experiments of L-histidine monolith revealed satisfactory dynamic binding capacity when compared to other matrices [1]. Overall, purification methodologies can benefit from affinity analysis provided by SPR biosensor. The combination of L-histidine and 1-benzyl-L-histine ligands with monolithic supports can be a promising strategy to purify the sc pDNA with the desirable purity degree for pharmaceutical applications, such as DNA vaccines.
{"title":"Screening of L-histidine based ligands to purify the supercoiled plasmid DNA isoform","authors":"Lúcia F. A. Amorim, F. Sousa, J. Queiroz, C. Cruz, Â. Sousa","doi":"10.1109/ENBENG.2015.7088829","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088829","url":null,"abstract":"Summary form only given. Cervical cancer and high risk human papillomavirus (HPV) are highly associated and currently, the preventive vaccines only induce the antibody immunity. The urge to attenuate lesions and tumour progressions led to development of DNA vaccines, able to induce both humoural and cellular immune responses. Plasmid DNA (pDNA) is being widely explored as a non-viral vector due to its lack of toxicity, low cost manufacture and high expression levels. To produce an effective pDNA vaccine, a biotechnology platform is required and every single step has to be optimized in order to obtain this molecule with high purity degree, able to efficiently transfect eukaryotic cells with satisfactory expression of the target gene. Amino acid-affinity chromatography has been considered a promissory approach that selectively recognizes the biologically active pDNA topology, the supercoiled (sc) isoform. Thus, the aim of this work was to perform a screening of L-histidine-based amino acids employing the surface plasmon resonance (SPR) technique in order to modify a monolithic support with the suitable ligand for sc pDNA purification. Several experiments were performed with three plasmids of different sizes (6.05, 8.70 and 14 Kbp) and different isoforms (open circular, sc and linear), separately. The SPR results revealed that the overall affinity of plasmids to L-histidine-based ligands was high (KD >10-8 M) and the highest affinity was found for HPV-16 E6/E7. Therefore, L-histidine and 1-benzyl-L-histidine ligands were immobilized on epoxy monoliths and several chromatographic studies were accomplished with the aforementioned samples. In general, the sc isoform developed strong interactions with the modified supports and the separation of plasmid isoforms was achieved by decreasing the ammonium sulfate concentration. Lower salt content was required in the 1-benzyl-L-histidine monolith because of stronger interactions promoted with pDNA. The separation of plasmid isoforms remained unchanged by flow rate variations. The breakthrough experiments of L-histidine monolith revealed satisfactory dynamic binding capacity when compared to other matrices [1]. Overall, purification methodologies can benefit from affinity analysis provided by SPR biosensor. The combination of L-histidine and 1-benzyl-L-histine ligands with monolithic supports can be a promising strategy to purify the sc pDNA with the desirable purity degree for pharmaceutical applications, such as DNA vaccines.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128514544","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}
Pub Date : 2015-04-20DOI: 10.1109/ENBENG.2015.7088856
V. Carneiro, H. Puga
Auxetic materials are characterized by getting thiner/ larger in tension/compression. This counterintuitive behavior is advantageous in specific applications such as self-expandable stents. There are currently some stents that make use of this behavior, nevertheless there are still auxetic geometries that are not explored in this field. Additionally, Pure Magnesium is a promising material to manufacture bioabsorbable stents. This study presents the modelation of novel auxetic self-expanding stents based in Reentrant and Chiral geometries. They are simulated using Finite Element analysis to determine the presence of negative Poisson's ratios and if they are a possible solution for further stent development. It is concluded that such modelations show low values of Poisson's ratio and may be a viable possibility to obtain a new generation of self-expanding stents.
{"title":"Modeling and elastic simulation of auxetic magnesium stents","authors":"V. Carneiro, H. Puga","doi":"10.1109/ENBENG.2015.7088856","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088856","url":null,"abstract":"Auxetic materials are characterized by getting thiner/ larger in tension/compression. This counterintuitive behavior is advantageous in specific applications such as self-expandable stents. There are currently some stents that make use of this behavior, nevertheless there are still auxetic geometries that are not explored in this field. Additionally, Pure Magnesium is a promising material to manufacture bioabsorbable stents. This study presents the modelation of novel auxetic self-expanding stents based in Reentrant and Chiral geometries. They are simulated using Finite Element analysis to determine the presence of negative Poisson's ratios and if they are a possible solution for further stent development. It is concluded that such modelations show low values of Poisson's ratio and may be a viable possibility to obtain a new generation of self-expanding stents.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125797364","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}
Pub Date : 2015-04-20DOI: 10.1109/ENBENG.2015.7088812
R. Correia, Ana Pereira, J. Gabriel, Luis Antunes
Anaesthesia chambers are a method to induce an anaesthetic state to small mammals in laboratory procedures (e.g. mice), when animal handling can alter the outcome of the tests performed due to induced stress [1]. Loss of rightning reflex (LORR) and respiratory rate (RR) are parameters in which the technician relies to evaluate the anaesthesia depth on a visual evaluation. Piezoelectric elements have been successfully presented as a method to monitor vital signs, namely RR, in mice as a non-invasive method [2]. In previous work of this research team, an instrumented chamber with built-in piezoelectric sensors was presented and an accurate measure of the subject's RR was achieved [3]. The aim for this work is to present a preliminary integrated solution for LORR detection and RR monitoring, in order to be implemented in future anaesthesia studies. The tests were conducted on three white NMRI female mice's, aging 2 months old and weighing between 38.6 and 40.8g. Each mice was placed inside the chamber and the anaesthetic state was induced at a 5% isoflurane concentration (Isoflo, Esteve Farma Lda., Carnaxide, Portugal) in 100% oxygen at 1 L/min until LORR. Then, the anaesthesia delivery was interrupted, and 100% oxygen at a delivery rate of 2 L/min was provided until recovery of the reflex was observed. One piezoelectric KPSG-100 (30 Vp-p, 1.2±0.2 kHz, Kingstate) sensor was placed underneath the anaesthesia chamber's footholds. The sensor was connected to a Kistler 5073-A model charge amplifier (Kistler Corporation, NY, USA). The charge amplifier was configured using Kirstler's ManuWare software. The amplified signal output was then measured using a NI DAQ USB-6251, 16-bit, Multifunction I/O device (National Instruments, Austin, TX, USA) and filtered using a point-to-point 2nd order Butterworth band-pass filter with bandwidth from 0.5 Hz to 5 Hz, in a developed acquisition application in LabVIEW 2013 (National Instruments, USA). LORR detection was achieved through the implementation of an identification algorithm, regarding piezoelectric signal obtained through the mice movement within the chamber or from its breathing cycle. RR was calculated using a peak-to-peak detection algorithm. In the tests performed, it was possible to correctly identify the LORR moment and to achieve RR monitoring during the anaesthesia protocol (Fig 1.). RR variation due to the anaesthesia depth was also noticeable, from a lowering RR right after LORR, to a dissipation of anaesthetic until the moment of recovery. Comparing with the previous results [3], the implementation of the new setup enables a simple LORR detection method with an enhanced RR related signal amplitude (8 mVp-p to 32 mVp-p). Further tests are recommended to observe the system response to mice weight variations and positioning within the chamber. Nonetheless, with the respective validation, the presented system indicates a novel method for anaesthesia related studies and laboratory animal handling.
{"title":"Anaesthesia induction in small mammal's using an instrumented anaesthetic chamber","authors":"R. Correia, Ana Pereira, J. Gabriel, Luis Antunes","doi":"10.1109/ENBENG.2015.7088812","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088812","url":null,"abstract":"Anaesthesia chambers are a method to induce an anaesthetic state to small mammals in laboratory procedures (e.g. mice), when animal handling can alter the outcome of the tests performed due to induced stress [1]. Loss of rightning reflex (LORR) and respiratory rate (RR) are parameters in which the technician relies to evaluate the anaesthesia depth on a visual evaluation. Piezoelectric elements have been successfully presented as a method to monitor vital signs, namely RR, in mice as a non-invasive method [2]. In previous work of this research team, an instrumented chamber with built-in piezoelectric sensors was presented and an accurate measure of the subject's RR was achieved [3]. The aim for this work is to present a preliminary integrated solution for LORR detection and RR monitoring, in order to be implemented in future anaesthesia studies. The tests were conducted on three white NMRI female mice's, aging 2 months old and weighing between 38.6 and 40.8g. Each mice was placed inside the chamber and the anaesthetic state was induced at a 5% isoflurane concentration (Isoflo, Esteve Farma Lda., Carnaxide, Portugal) in 100% oxygen at 1 L/min until LORR. Then, the anaesthesia delivery was interrupted, and 100% oxygen at a delivery rate of 2 L/min was provided until recovery of the reflex was observed. One piezoelectric KPSG-100 (30 Vp-p, 1.2±0.2 kHz, Kingstate) sensor was placed underneath the anaesthesia chamber's footholds. The sensor was connected to a Kistler 5073-A model charge amplifier (Kistler Corporation, NY, USA). The charge amplifier was configured using Kirstler's ManuWare software. The amplified signal output was then measured using a NI DAQ USB-6251, 16-bit, Multifunction I/O device (National Instruments, Austin, TX, USA) and filtered using a point-to-point 2nd order Butterworth band-pass filter with bandwidth from 0.5 Hz to 5 Hz, in a developed acquisition application in LabVIEW 2013 (National Instruments, USA). LORR detection was achieved through the implementation of an identification algorithm, regarding piezoelectric signal obtained through the mice movement within the chamber or from its breathing cycle. RR was calculated using a peak-to-peak detection algorithm. In the tests performed, it was possible to correctly identify the LORR moment and to achieve RR monitoring during the anaesthesia protocol (Fig 1.). RR variation due to the anaesthesia depth was also noticeable, from a lowering RR right after LORR, to a dissipation of anaesthetic until the moment of recovery. Comparing with the previous results [3], the implementation of the new setup enables a simple LORR detection method with an enhanced RR related signal amplitude (8 mVp-p to 32 mVp-p). Further tests are recommended to observe the system response to mice weight variations and positioning within the chamber. Nonetheless, with the respective validation, the presented system indicates a novel method for anaesthesia related studies and laboratory animal handling.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116542911","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}
Pub Date : 2015-04-20DOI: 10.1109/ENBENG.2015.7088822
R. Alves, D. Borges Faria, D. Campos Costa, J. Tavares
Myocardial perfusion is commonly studied based on the evaluation of the left ventricular function using stress-rest gated myocardial perfusion single photon emission computed tomography (GSPECT), which provides a suitable identification of the myocardial region, facilitating the localization and characterization of perfusion abnormalities. The prevalence and clinical predictors of myocardial ischemia and infarct can be assessed from GSPECT images. Here, techniques of image analysis, namely image segmentation and registration, are integrated to automatically extract a set of features from myocardial perfusion SPECT images that are automatically classified as related to myocardial perfusion disorders or not. The solution implemented can be divided into two main parts: 1) building of a template image, segmentation of the template image and computation of its dimensions; 2) registration of the image under study with the template image previously built, extraction of the image features, statistical analysis and classification. It should be noted that the first step just needs to be performed once for a particular population. Hence, algorithms of image segmentation, registration and classification were used, specifically of k-means clustering, rigid and deformable registration and classification. The computational solution developed was tested using 180 3D images from 48 patients with healthy cardiac condition and 72 3D images from 12 patients with cardiac diseases, which were reconstructed using the filtered back projection algorithm and a low pass Butterworth filter or iterative algorithms. The images were classified into two classes: “abnormality present” and “abnormality not present”. The classification was assessed using five parameters: sensitivity, specificity, precision, accuracy and mean error rate. The results obtained shown that the solution is effective, both for female and male cardiac SPECT images that can have very different structural dimensions. Particularly, the solution demonstrated reasonable robustness against the two major difficulties in SPECT image analysis: image noise and low resolution. Furthermore, the classifier used demonstrated good specificity and accuracy, Table 1.
{"title":"Analysis of gated myocardial perfusion spect images based on computational image registration","authors":"R. Alves, D. Borges Faria, D. Campos Costa, J. Tavares","doi":"10.1109/ENBENG.2015.7088822","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088822","url":null,"abstract":"Myocardial perfusion is commonly studied based on the evaluation of the left ventricular function using stress-rest gated myocardial perfusion single photon emission computed tomography (GSPECT), which provides a suitable identification of the myocardial region, facilitating the localization and characterization of perfusion abnormalities. The prevalence and clinical predictors of myocardial ischemia and infarct can be assessed from GSPECT images. Here, techniques of image analysis, namely image segmentation and registration, are integrated to automatically extract a set of features from myocardial perfusion SPECT images that are automatically classified as related to myocardial perfusion disorders or not. The solution implemented can be divided into two main parts: 1) building of a template image, segmentation of the template image and computation of its dimensions; 2) registration of the image under study with the template image previously built, extraction of the image features, statistical analysis and classification. It should be noted that the first step just needs to be performed once for a particular population. Hence, algorithms of image segmentation, registration and classification were used, specifically of k-means clustering, rigid and deformable registration and classification. The computational solution developed was tested using 180 3D images from 48 patients with healthy cardiac condition and 72 3D images from 12 patients with cardiac diseases, which were reconstructed using the filtered back projection algorithm and a low pass Butterworth filter or iterative algorithms. The images were classified into two classes: “abnormality present” and “abnormality not present”. The classification was assessed using five parameters: sensitivity, specificity, precision, accuracy and mean error rate. The results obtained shown that the solution is effective, both for female and male cardiac SPECT images that can have very different structural dimensions. Particularly, the solution demonstrated reasonable robustness against the two major difficulties in SPECT image analysis: image noise and low resolution. Furthermore, the classifier used demonstrated good specificity and accuracy, Table 1.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131201293","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}
Pub Date : 2015-04-20DOI: 10.1109/ENBENG.2015.7088886
J. P. Martins, C. J. Alves, E. Neto, D. M. Moreira, M. Xavier, D. Sousa, I. Alencastre, M. Lamghari
The central nervous system (CNS) and the periphery are closely associated in the regulation of body homeostasis. In fact, in both physiological and pathological conditions, the CNS showed to be targeted by peripheral system molecules, which are able to generate adaptive responses under the tight control of the hypothalamus. In spite of having a well-recognized importance, the mechanisms underlying this communication are still unclear. Two major routes have been proposed to explain the transmission of information from the periphery to the CNS: a sensory pathway, through the peripheral nerves and a humoral pathway, through the bloodstream. In the present work, in vitro blood-brain barrier cultures and hypothalamic organotypic cultures were characterized with the main goal to enable the establishment of a platform to investigate the communication between the periphery and the CNS through the humoral pathway.
{"title":"An in vitro approach to unravel the modulation of the hypothalamic system by blood-circulating factors","authors":"J. P. Martins, C. J. Alves, E. Neto, D. M. Moreira, M. Xavier, D. Sousa, I. Alencastre, M. Lamghari","doi":"10.1109/ENBENG.2015.7088886","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088886","url":null,"abstract":"The central nervous system (CNS) and the periphery are closely associated in the regulation of body homeostasis. In fact, in both physiological and pathological conditions, the CNS showed to be targeted by peripheral system molecules, which are able to generate adaptive responses under the tight control of the hypothalamus. In spite of having a well-recognized importance, the mechanisms underlying this communication are still unclear. Two major routes have been proposed to explain the transmission of information from the periphery to the CNS: a sensory pathway, through the peripheral nerves and a humoral pathway, through the bloodstream. In the present work, in vitro blood-brain barrier cultures and hypothalamic organotypic cultures were characterized with the main goal to enable the establishment of a platform to investigate the communication between the periphery and the CNS through the humoral pathway.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133393502","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}
Pub Date : 2015-04-20DOI: 10.1109/ENBENG.2015.7088847
Rita Martins, P. Martins, T. Mascarenhas, R. Jorge
Vaginal tissue is known to be stiffer when load is applied in the longitudinal direction of its fibers rather than the transverse direction. However, little attention has been paid to the differences in the material parameters that characterize these tissues' behavior. The goal of this study was to evaluate the differences of vaginal tissue's material parameters for constitutive modeling. For this purpose, experimental data from previous uniaxial tensile tests, in the longitudinal and transverse directions, of anterior and posterior vaginal wall samples were used. The material parameters were determined for Weiss modified and Mooney-Rivlin material models using an analytical method. As expected, different mechanical properties reflected different material parameters. Weiss modified material model confirmed to be suitable for modeling the longitudinal direction but inaccurate in the transverse direction, whereas Mooney-Rivlin's revealed to be more adequate on modeling the transverse direction.
{"title":"Evaluation of material model parameters of vaginal tissue with different fiber orientation","authors":"Rita Martins, P. Martins, T. Mascarenhas, R. Jorge","doi":"10.1109/ENBENG.2015.7088847","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088847","url":null,"abstract":"Vaginal tissue is known to be stiffer when load is applied in the longitudinal direction of its fibers rather than the transverse direction. However, little attention has been paid to the differences in the material parameters that characterize these tissues' behavior. The goal of this study was to evaluate the differences of vaginal tissue's material parameters for constitutive modeling. For this purpose, experimental data from previous uniaxial tensile tests, in the longitudinal and transverse directions, of anterior and posterior vaginal wall samples were used. The material parameters were determined for Weiss modified and Mooney-Rivlin material models using an analytical method. As expected, different mechanical properties reflected different material parameters. Weiss modified material model confirmed to be suitable for modeling the longitudinal direction but inaccurate in the transverse direction, whereas Mooney-Rivlin's revealed to be more adequate on modeling the transverse direction.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132895454","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}
Pub Date : 2015-04-20DOI: 10.1109/ENBENG.2015.7088894
Sofia Sousa, J. Claro
A novel 3D multibody system (MBS) model of the human lumbar spine is presented, allowing the dynamic study of the entire lumbar spine and/or of each one of its intervertebral discs (IVD) by itself, predicting the complex stress conditions due to any arrangement of the main movements: flexion-extension, lateral bending and axial rotation, compression or traction. The multibody model is composed by six vertebrae, taken as rigid bodies, interconnected through fifty non-linear Maxwell elements, emulating the five intervertebral discs and twenty main ligaments, plus the facets. The intervertebral discs (IVD) three orthogonal axes rotation and translation behavior was characterized via a dedicated high degree viscoelastic finite elements model, developed within the research group, whereas the ligaments (PLL, ALL, SSL-ISL, LF) were typified through published experimental data. In both cases, the resulting MBS non-linear spring joints characteristics were carefully checked against the original data sources, and similarity of response assured within the physiological range of motion. The model, thoroughly validated against in vitro and in vivo available experimental data, showed to be very stable and with remarkably light computational demands.
提出了一种新的人体腰椎三维多体系统(MBS)模型，允许对整个腰椎和/或其每个椎间盘(IVD)本身进行动态研究，预测由于任何主要运动安排而导致的复杂应力条件:屈伸，侧向弯曲和轴向旋转，压缩或牵引。多体模型由6个椎骨组成，作为刚体，通过50个非线性Maxwell单元相互连接，模拟5个椎间盘和20个主要韧带，加上切面。椎间盘(IVD)的三个正交轴旋转和平移行为通过专门的高粘弹性有限元模型进行表征，该模型由研究组开发，而韧带(PLL, ALL, SSL-ISL, LF)通过发表的实验数据进行分类。在这两种情况下，所得到的MBS非线性弹簧关节特性与原始数据源进行了仔细检查，并在生理运动范围内保证了响应的相似性。该模型经过体外和体内实验数据的彻底验证，显示出非常稳定且计算需求非常轻。
{"title":"Optimization of a multibody system of the human lumbar spine","authors":"Sofia Sousa, J. Claro","doi":"10.1109/ENBENG.2015.7088894","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088894","url":null,"abstract":"A novel 3D multibody system (MBS) model of the human lumbar spine is presented, allowing the dynamic study of the entire lumbar spine and/or of each one of its intervertebral discs (IVD) by itself, predicting the complex stress conditions due to any arrangement of the main movements: flexion-extension, lateral bending and axial rotation, compression or traction. The multibody model is composed by six vertebrae, taken as rigid bodies, interconnected through fifty non-linear Maxwell elements, emulating the five intervertebral discs and twenty main ligaments, plus the facets. The intervertebral discs (IVD) three orthogonal axes rotation and translation behavior was characterized via a dedicated high degree viscoelastic finite elements model, developed within the research group, whereas the ligaments (PLL, ALL, SSL-ISL, LF) were typified through published experimental data. In both cases, the resulting MBS non-linear spring joints characteristics were carefully checked against the original data sources, and similarity of response assured within the physiological range of motion. The model, thoroughly validated against in vitro and in vivo available experimental data, showed to be very stable and with remarkably light computational demands.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"549 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123508792","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}
Pub Date : 2015-04-20DOI: 10.1109/ENBENG.2015.7088861
H. Dinis, P. Mendes
Wireless power transfer is a hot topic due to the growth of implanted device solutions which, as they get smaller and smarter, demand new solutions to power them up. These solutions need to keep the power level, namely SAR (specific absorption ratio) below a determined safety standard and to allow the device to be as small as possible. Current fabrication techniques allow the creation of ultra-small 3D antennas integrated on silicon wafers, which can lead to the miniaturization of implantable devices due to the possible reduction or even elimination of battery size. To evaluate this possibility, the antenna must be tested in conditions close to real working conditions, requiring the use of human body phantoms. This paper proposes a solution to measure the power received by an ultra-small antenna placed inside a phantom, without the use of coaxial cables attached to the device. Instead, an optoelectronic mechanism is used to route the received power to an optical fiber, and an optical spectrum analyzer is used to measure the received power.
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Pub Date : 2015-04-20DOI: 10.1109/ENBENG.2015.7088805
A. Vieira, H. Sobral, J. Ferreira, Paulo Ferreira, Stephane Cruz, M. Crisostomo, A. Coimbra
Summary form only given. Human gait analysis can be performed by using a treadmill and two aligned web cameras, positioned one on each side of the treadmill. In this system, passive marks are positioned on person's joints and various angles of the gait are recorded by the cameras at different speeds of the treadmill. The treadmill's speed is appropriated for each person clinical case. This system is a substantial evolution from [1] at a much lower cost than [2] and [3]. This research project aims to create software capable of generating joint trajectory references of healthy people gaits, considering height, weight, age and test speed. These trajectories will be used as reference to compare with the data of a person with an abnormal gait. From this comparison a classification of the severity of the pathology will be obtained. The developed software uses an artificial neural network, based on 97 samples from 20 walking people with healthy gaits, collected on treadmill's tests. 70% of the samples were used for training, 5% for validation and 25% for testing. The two best neural networks for the knee joints are constituted by 10 or 12 neurons in the hidden layer, showing regression values higher than 97%. They have four inputs (height, weight, age and test speed) and the output is the reference knee joint trajectory. In this project it is also used the extreme learning machine, as an alternative computational intelligence approach of the neural network. With this software physiotherapists can make gait pattern comparisons taking into account the specific characteristics of each person, instead of comparisons with the standard gait patterns of the literature that does not differentiate for different characteristics. The system was tested analyzing the gait of 7 persons who were subjected to ligamentoplasty (surgical reconstruction) about two years ago, after suffering a rupture of the anterior cruciate ligament of the knee. Collected data were compared with the trajectory references generated by the software for each person taking into account their physical characteristics. The results show that this software makes it possible to analyze and quantify the severity of gait pathologies, which is a significant improvement to the present subjective analysis practice.
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