Pub Date : 2015-04-20DOI: 10.1109/ENBENG.2015.7088818
H. Simões, P. Crespo
Radiotherapy (RT) is nowadays, after surgery, the most frequently used cancer treatment. Modern RT techniques provide increasingly higher conformality, a potential invaluable clinical benefit to the patient. Consequently, patient misalignments and changing internal anatomy (e.g. tissue swelling, edema, inflammation or tumor shrinkage/growth) are also becoming more critical since higher conformality may equally represent a higher risk of target underdosage or organ-at-risk overdosage. Therefore, state-of-the-art image-guided radiotherapy (IGRT) is the modern technique that aims at providing feedback to the radiation oncologist in regard to these matters, sometimes at the cost of increased dosage or treatment fraction time (e.g. kilo and megavoltage cone-beam computed tomography), other times providing insufficient clinical information. Our group is investigating a novel imaging system especially designed for assisting RT treatments. Such system, termed OrthoCT, consists in operating a dedicated X-ray detection system specially built for collecting selected patient-scattered radiation. Our team has shown by simulation [1, 2] and experiments [2, 3] that collecting such radiation allows for a rotation-free, 3D imaging of the inner morphology of the target (patient). The rotation-free and low dose 3D imaging capability of OrthoCT renders it very attractive due to its usefulness for so-called “on-board” patient imaging. A small-scale, bi-dimensional system is under construction for proof-of-principle validation. It consists of 4 crystals lines separated by collimator slices. Each crystal line is composed by 50 gadolinium oxyorthosilicate (GSO) crystals with a front-area of 4 × 4 mm2, forming a total line length of 200 mm. As light detector, a photomultiplier tube (PMT) will be used. Since the sensitive area of the PMT is 50 × 50 mm2, a light-guide to drive the light between the GSO crystals and the PMT is required. The aim of this work was the optimization, by means of Monte Carlo simulation, of the light-guide dimensions. The setup implemented into Geant4 is shown schematically in Figure 1, left. Such apparatus was tested for different theta angles (i.e. different light-guide length L). In Figure 1, right the count profiles obtained for different theta values are presented. The length L corresponding to θ = 7.5, 10, 12.5, and 15 degrees was 570, 425, 338, and 280 mm, respectively. Thus, smaller angles require larger light-guide lengths and, consequently, light losses in the path length are also higher. By analyzing the plots, the profile obtained for θ = 12.5 degrees shows a great compromise between the fraction of photons detected and the guide-light dimensions. For angles θ > 15 degrees the detection of the light coming from peripheric crystals is compromised. In concluding, the length of the guide-light must be approximately 340 mm.
{"title":"A light-guide optimization for proof-of-principle of a megavoltage orthogonal ray imaging prototype","authors":"H. Simões, P. Crespo","doi":"10.1109/ENBENG.2015.7088818","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088818","url":null,"abstract":"Radiotherapy (RT) is nowadays, after surgery, the most frequently used cancer treatment. Modern RT techniques provide increasingly higher conformality, a potential invaluable clinical benefit to the patient. Consequently, patient misalignments and changing internal anatomy (e.g. tissue swelling, edema, inflammation or tumor shrinkage/growth) are also becoming more critical since higher conformality may equally represent a higher risk of target underdosage or organ-at-risk overdosage. Therefore, state-of-the-art image-guided radiotherapy (IGRT) is the modern technique that aims at providing feedback to the radiation oncologist in regard to these matters, sometimes at the cost of increased dosage or treatment fraction time (e.g. kilo and megavoltage cone-beam computed tomography), other times providing insufficient clinical information. Our group is investigating a novel imaging system especially designed for assisting RT treatments. Such system, termed OrthoCT, consists in operating a dedicated X-ray detection system specially built for collecting selected patient-scattered radiation. Our team has shown by simulation [1, 2] and experiments [2, 3] that collecting such radiation allows for a rotation-free, 3D imaging of the inner morphology of the target (patient). The rotation-free and low dose 3D imaging capability of OrthoCT renders it very attractive due to its usefulness for so-called “on-board” patient imaging. A small-scale, bi-dimensional system is under construction for proof-of-principle validation. It consists of 4 crystals lines separated by collimator slices. Each crystal line is composed by 50 gadolinium oxyorthosilicate (GSO) crystals with a front-area of 4 × 4 mm2, forming a total line length of 200 mm. As light detector, a photomultiplier tube (PMT) will be used. Since the sensitive area of the PMT is 50 × 50 mm2, a light-guide to drive the light between the GSO crystals and the PMT is required. The aim of this work was the optimization, by means of Monte Carlo simulation, of the light-guide dimensions. The setup implemented into Geant4 is shown schematically in Figure 1, left. Such apparatus was tested for different theta angles (i.e. different light-guide length L). In Figure 1, right the count profiles obtained for different theta values are presented. The length L corresponding to θ = 7.5, 10, 12.5, and 15 degrees was 570, 425, 338, and 280 mm, respectively. Thus, smaller angles require larger light-guide lengths and, consequently, light losses in the path length are also higher. By analyzing the plots, the profile obtained for θ = 12.5 degrees shows a great compromise between the fraction of photons detected and the guide-light dimensions. For angles θ > 15 degrees the detection of the light coming from peripheric crystals is compromised. In concluding, the length of the guide-light must be approximately 340 mm.","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":"130760903","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.2015.7088882
J. Belinha, L. Dinis, R. Jorge
In this work the bone density distribution in the vicinity of femoral implants is predicted using a topology optimization model, based on deformation energy methods. The bone tissue is an efficient and optimized anisotropic biological material, capable of maximizing the structural stiffness by itself. In this work, the mechanical behaviour of the bone tissue is determined using a continuous anisotropic mathematical phenomenological law developed based on experimental data available in the literature. Thus, this law permits to correlate the bone density with the obtained level of stress. In order to obtain the displacement and stress fields a numerical meshless technique is used: the Natural Neighbour Radial Point Interpolator Method (NNRPIM). The NNRPIM presents various advantages in the topologic analysis comparing with other discrete numerical methods such as the Finite Element Method.
{"title":"The osteointegration numerical prediction of a femur stem using a meshless approach","authors":"J. Belinha, L. Dinis, R. Jorge","doi":"10.1109/ENBENG.2015.7088882","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088882","url":null,"abstract":"In this work the bone density distribution in the vicinity of femoral implants is predicted using a topology optimization model, based on deformation energy methods. The bone tissue is an efficient and optimized anisotropic biological material, capable of maximizing the structural stiffness by itself. In this work, the mechanical behaviour of the bone tissue is determined using a continuous anisotropic mathematical phenomenological law developed based on experimental data available in the literature. Thus, this law permits to correlate the bone density with the obtained level of stress. In order to obtain the displacement and stress fields a numerical meshless technique is used: the Natural Neighbour Radial Point Interpolator Method (NNRPIM). The NNRPIM presents various advantages in the topologic analysis comparing with other discrete numerical methods such as the Finite Element Method.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"22 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":"121105116","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.2015.7088809
J. Santinha, Nadia S. M. Goncalves, A. Mora, A. Ribeiro, J. Fonseca
Summary form only given. Escherichia coli is an established model for the study of protein aggregation in vivo, a process that is related to its aging. These aggregates have a predisposition for locating at the cell poles, which, following cell division, results in asymmetric damage distribution by the two poles of the daughter cells. Such preference for polar localization is due the occlusion caused by the nucleoid at midcell. To study this process, it is necessary to correlate the spatial location of the protein aggregates and nucleoids during a cell life cycle. For this, and while neither structure has clear borders, it is necessary to perform their segmentation from fluorescence microscopy images. Here, we propose an adaptation of the method used in automatic Drusen detection in retinal images for detecting and segmenting DAPI-stained nucleoids at each stage of the cell cycle. We use the GPL algorithm to detect the number of nucleoids inside each cell. For the segmentation step, according to the number of nucleoids present in the cell, we use either one or two 3-dimensional, modified Gaussian functions as a point spread function model. By setting the amplitude profile parameter with a value equal to 10, the segmentation threshold is directly obtained from the value of z0. The method was applied to images of cells at different temperatures. Table 1 shows the extracted relative nucleoid major axis length for cells with one and with two nucleoids, in each temperature condition. From Table 1, the mean relative nucleoid major axis length decreases with increasing temperature for both cells with one and with two nucleoids, as expected by visual inspection of the images. Also, the positions of the borders of the nucleoid detected by our method, for cells with one nucleoid, are consistent with regions of anisotropies in aggregates motion reported in our previous studies. Additionally, the locations of the nucleoids for both cells with one and with two nucleoids are in agreement with the observed spatial distribution of the protein aggregates, which remain outside the nucleoid region according to our previous studies. These results demonstrate that the proposed method is able to differentiate between one and two nucleoids, perform their segmentation efficiently, and extract with precision the nucleoid(s) size along both the major and minor cell axis.
{"title":"A nucleoid segmentation method robust to varying nucleoid number","authors":"J. Santinha, Nadia S. M. Goncalves, A. Mora, A. Ribeiro, J. Fonseca","doi":"10.1109/ENBENG.2015.7088809","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088809","url":null,"abstract":"Summary form only given. Escherichia coli is an established model for the study of protein aggregation in vivo, a process that is related to its aging. These aggregates have a predisposition for locating at the cell poles, which, following cell division, results in asymmetric damage distribution by the two poles of the daughter cells. Such preference for polar localization is due the occlusion caused by the nucleoid at midcell. To study this process, it is necessary to correlate the spatial location of the protein aggregates and nucleoids during a cell life cycle. For this, and while neither structure has clear borders, it is necessary to perform their segmentation from fluorescence microscopy images. Here, we propose an adaptation of the method used in automatic Drusen detection in retinal images for detecting and segmenting DAPI-stained nucleoids at each stage of the cell cycle. We use the GPL algorithm to detect the number of nucleoids inside each cell. For the segmentation step, according to the number of nucleoids present in the cell, we use either one or two 3-dimensional, modified Gaussian functions as a point spread function model. By setting the amplitude profile parameter with a value equal to 10, the segmentation threshold is directly obtained from the value of z0. The method was applied to images of cells at different temperatures. Table 1 shows the extracted relative nucleoid major axis length for cells with one and with two nucleoids, in each temperature condition. From Table 1, the mean relative nucleoid major axis length decreases with increasing temperature for both cells with one and with two nucleoids, as expected by visual inspection of the images. Also, the positions of the borders of the nucleoid detected by our method, for cells with one nucleoid, are consistent with regions of anisotropies in aggregates motion reported in our previous studies. Additionally, the locations of the nucleoids for both cells with one and with two nucleoids are in agreement with the observed spatial distribution of the protein aggregates, which remain outside the nucleoid region according to our previous studies. These results demonstrate that the proposed method is able to differentiate between one and two nucleoids, perform their segmentation efficiently, and extract with precision the nucleoid(s) size along both the major and minor cell axis.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"42 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":"126306023","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.2015.7088836
N. Ramião, P. Martins, A. Fernandes, Maria da Luz Barroso, D. Santos
Silicone breast implants have been used for cosmetic and reconstructive breast surgery for several decades. Rupture and silicone leakage are well-known complications for silicone mammary implants. The public debate and awareness about the breast implants safety started because of the scandal associated with the Poly Implant Prostheses (PIP) manufacturer. In order to analyze rupture in these breast implants we carried out a mechanical study which included an evaluation of the mechanical shell properties, so that we can identify if the shell properties are uniform for the whole implant.
{"title":"Mechanical tests in all regions of the PIP breast implants","authors":"N. Ramião, P. Martins, A. Fernandes, Maria da Luz Barroso, D. Santos","doi":"10.1109/ENBENG.2015.7088836","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088836","url":null,"abstract":"Silicone breast implants have been used for cosmetic and reconstructive breast surgery for several decades. Rupture and silicone leakage are well-known complications for silicone mammary implants. The public debate and awareness about the breast implants safety started because of the scandal associated with the Poly Implant Prostheses (PIP) manufacturer. In order to analyze rupture in these breast implants we carried out a mechanical study which included an evaluation of the mechanical shell properties, so that we can identify if the shell properties are uniform for the whole implant.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"08 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":"129629758","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.2015.7088845
T. Da Roza, R. Jorge, J. Duarte, S. Brandão, T. Mascarenhas, I. Ramos
Changes in the morphology of the pelvic floor muscles (PFM) or in their attachment points can cause functional weakness, especially when during effort. When there is the need to counteract the increase in intra-abdominal pressure, urinary leakage may occur, which may in turn be related to the reduction of Moment of Inertia (MOI). We aimed to test the relation between muscle morphology, MOI and muscle displacement during computational simulation of valsalva maneuver. For that purpose, axial MRI images from five athletes were acquired. Measures of muscle thickness and area were taken, and the MOI and cross-sectional area were calculated using segmentation splines from the Inventor® software. Additionally, biomechanical models were through numerical simulation of valsalva maneuver using the Abaqus® software. The results showed an association between MOI and muscle displacement (p=0.037; r=-0.900) and thickness (p=0.037; r=0.900). Muscle area showed no significative association with the displacement during valsalva maneuver.
{"title":"Relationship between area and moment of inertia with pubovisceral muscle displacement by biomechanical models","authors":"T. Da Roza, R. Jorge, J. Duarte, S. Brandão, T. Mascarenhas, I. Ramos","doi":"10.1109/ENBENG.2015.7088845","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088845","url":null,"abstract":"Changes in the morphology of the pelvic floor muscles (PFM) or in their attachment points can cause functional weakness, especially when during effort. When there is the need to counteract the increase in intra-abdominal pressure, urinary leakage may occur, which may in turn be related to the reduction of Moment of Inertia (MOI). We aimed to test the relation between muscle morphology, MOI and muscle displacement during computational simulation of valsalva maneuver. For that purpose, axial MRI images from five athletes were acquired. Measures of muscle thickness and area were taken, and the MOI and cross-sectional area were calculated using segmentation splines from the Inventor® software. Additionally, biomechanical models were through numerical simulation of valsalva maneuver using the Abaqus® software. The results showed an association between MOI and muscle displacement (p=0.037; r=-0.900) and thickness (p=0.037; r=0.900). Muscle area showed no significative association with the displacement during valsalva maneuver.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"51 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":"121506354","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 : 2015-02-26DOI: 10.1109/ENBENG.2015.7088871
T. S. Monteiro, S. Cardoso, L. Gonçalves, G. Minas
Poly(dimethylsiloxane) (PDMS) is an organosilicon polymer widely used in the fabrication of microfluidic systems to integrate biochips. In this study, we propose the use of an adapted PDMS mould for the creation of a miniaturized, reusable, reference electrode for in-chip electrochemical measurements. Through its integrated microfluidic system it is possible to replenish internal buffer solutions, unclog critical junctions and treat the electrode's surface, assuring a long term reuse of the same device. Planar Ag/AgCl reference electrodes were microfabricated over a passivated p-type Silicon Wafer. The PDMS mould, containing an integrated microfluidic system, was fabricated based on patterned SU-8 mould, which includes a lateral horizontal inlet access point. Surface oxidation was used for irreversible permanent bondage between flat surfaces. The final result was planar Ag/AgCl reference electrode with integrated microfluidic that allows for electrochemical analysis in biochips.
{"title":"PDMS encasing system for integrated lab-on-chip Ag/AgCl reference electrodes","authors":"T. S. Monteiro, S. Cardoso, L. Gonçalves, G. Minas","doi":"10.1109/ENBENG.2015.7088871","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088871","url":null,"abstract":"Poly(dimethylsiloxane) (PDMS) is an organosilicon polymer widely used in the fabrication of microfluidic systems to integrate biochips. In this study, we propose the use of an adapted PDMS mould for the creation of a miniaturized, reusable, reference electrode for in-chip electrochemical measurements. Through its integrated microfluidic system it is possible to replenish internal buffer solutions, unclog critical junctions and treat the electrode's surface, assuring a long term reuse of the same device. Planar Ag/AgCl reference electrodes were microfabricated over a passivated p-type Silicon Wafer. The PDMS mould, containing an integrated microfluidic system, was fabricated based on patterned SU-8 mould, which includes a lateral horizontal inlet access point. Surface oxidation was used for irreversible permanent bondage between flat surfaces. The final result was planar Ag/AgCl reference electrode with integrated microfluidic that allows for electrochemical analysis in biochips.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"270 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115599444","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 : 2015-02-26DOI: 10.1109/ENBENG.2015.7088852
V. Pinto, G. Minas, M. Correia-Neves
This paper presents the study of the PDMS (poly(dimethylsiloxane)) surface functionalization for the development of a microfluidic immunosensor that quantitatively analyss salivary cortisol by optical detection. The functionalization was performed using different antibodies immobilization methods on PDMS surface: (a) immobilization by passive adsorption on pristine PDMS; (b) silanization of PDMS surface with (3-aminopropyl)-triethoxysilane (APTES) to generate amino groups and posterior covalent immobilization of antibodies on APTES-PDMS using cross-linker glutaraldehyde (GA); (c) coating the PDMS surface with BSA to block nonspecific protein adsorption, and then covalent bond of the protein A via GA. In this last approach, the antibodies were covalently immobilized to protein A due to its high affinity with the constant fraction (Fc) region of the antibodies. Atomic force microscope (AFM) and spectrophotometric analysis demonstrated that the immobilization method using protein A is more efficient since a higher roughness and uniformity on the PDMS surface and higher absorbance signals were obtained.
{"title":"PDMS biofunctionalization study for the development of a microfluidic device: Application to salivary cortisol","authors":"V. Pinto, G. Minas, M. Correia-Neves","doi":"10.1109/ENBENG.2015.7088852","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088852","url":null,"abstract":"This paper presents the study of the PDMS (poly(dimethylsiloxane)) surface functionalization for the development of a microfluidic immunosensor that quantitatively analyss salivary cortisol by optical detection. The functionalization was performed using different antibodies immobilization methods on PDMS surface: (a) immobilization by passive adsorption on pristine PDMS; (b) silanization of PDMS surface with (3-aminopropyl)-triethoxysilane (APTES) to generate amino groups and posterior covalent immobilization of antibodies on APTES-PDMS using cross-linker glutaraldehyde (GA); (c) coating the PDMS surface with BSA to block nonspecific protein adsorption, and then covalent bond of the protein A via GA. In this last approach, the antibodies were covalently immobilized to protein A due to its high affinity with the constant fraction (Fc) region of the antibodies. Atomic force microscope (AFM) and spectrophotometric analysis demonstrated that the immobilization method using protein A is more efficient since a higher roughness and uniformity on the PDMS surface and higher absorbance signals were obtained.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114362335","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 : 2015-02-26DOI: 10.1109/ENBENG.2015.7088850
P. Sousa, L. R. Silva, L. Gonçalves, G. Minas
This paper reports the fabrication process and characterization of a flexible pressure sensor based on polydimethylsiloxane (PDMS) and multi-walled carbon nanotubes (CNT-PDMS). The proposed approach relies on patterned CNT-PDMS nanocomposite strain gauges fabricated with SU-8 microstructures (with the micropatterns) in a low-cost and simple fabrication process. This nanocomposite polymer is mounted over a PDMS membrane, which, in turn, lies on top of a PDMS diaphragm like structure. This configuration enables the PDMS membrane to bend when pressure is applied, thereby affecting the nanocomposite strain gauges, effectively changing their electrical resistance. Carbon nanotubes have several advantages such as excellent mechanical properties, high electrical conductivity and thermal stability. Furthermore, the measurement range of the proposed sensor can be adapted according to the application by varying the CNTs content and geometry of microstructure. In addition, the sensor's biocompatibility, low cost and simple fabrication makes it very appealing for biomechanical strain sensing. The sensor's sensitivity was about 0.073%ΔR/mmHg.
{"title":"Patterned CNT-PDMS nanocomposites for flexible pressure sensors","authors":"P. Sousa, L. R. Silva, L. Gonçalves, G. Minas","doi":"10.1109/ENBENG.2015.7088850","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088850","url":null,"abstract":"This paper reports the fabrication process and characterization of a flexible pressure sensor based on polydimethylsiloxane (PDMS) and multi-walled carbon nanotubes (CNT-PDMS). The proposed approach relies on patterned CNT-PDMS nanocomposite strain gauges fabricated with SU-8 microstructures (with the micropatterns) in a low-cost and simple fabrication process. This nanocomposite polymer is mounted over a PDMS membrane, which, in turn, lies on top of a PDMS diaphragm like structure. This configuration enables the PDMS membrane to bend when pressure is applied, thereby affecting the nanocomposite strain gauges, effectively changing their electrical resistance. Carbon nanotubes have several advantages such as excellent mechanical properties, high electrical conductivity and thermal stability. Furthermore, the measurement range of the proposed sensor can be adapted according to the application by varying the CNTs content and geometry of microstructure. In addition, the sensor's biocompatibility, low cost and simple fabrication makes it very appealing for biomechanical strain sensing. The sensor's sensitivity was about 0.073%ΔR/mmHg.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115048436","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 : 2015-02-26DOI: 10.1109/ENBENG.2015.7088885
J. Fernandes, F. Soares, G. Minas
Blood typing is a crucial step before any blood transfusion. However, sometimes in emergency situations there is no time to determine the blood of the patient beforehand. In this cases, O negative blood type is administered, which has a lesser incompatibility risk to the patient. Nowadays, the “gold standard” blood typing devices cannot be used in emergency situations due to their high response time (about 30 minutes). This paper reports a blood typing device that determines the ABO and Rh human phenotypes. This device is fast (response time - 5 min), low-cost, and portable. Characteristics that make it suitable to be used in emergency situations, contributing to a higher efficiency and quality in healthcare.
{"title":"A spectrophotometry based blood typing device","authors":"J. Fernandes, F. Soares, G. Minas","doi":"10.1109/ENBENG.2015.7088885","DOIUrl":"https://doi.org/10.1109/ENBENG.2015.7088885","url":null,"abstract":"Blood typing is a crucial step before any blood transfusion. However, sometimes in emergency situations there is no time to determine the blood of the patient beforehand. In this cases, O negative blood type is administered, which has a lesser incompatibility risk to the patient. Nowadays, the “gold standard” blood typing devices cannot be used in emergency situations due to their high response time (about 30 minutes). This paper reports a blood typing device that determines the ABO and Rh human phenotypes. This device is fast (response time - 5 min), low-cost, and portable. Characteristics that make it suitable to be used in emergency situations, contributing to a higher efficiency and quality in healthcare.","PeriodicalId":285567,"journal":{"name":"2015 IEEE 4th Portuguese Meeting on Bioengineering (ENBENG)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116994352","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 : 2015-02-01DOI: 10.1109/ENBENG.2015.7088867
Andre Gorgulho, F. Caramelo, M. Patrício
Quantification of positron emission tomography (PET) images using compartmental models requires the estimation of the tracer concentration in plasma as a function of time. Estimating this function directly from PET images, by measuring the tracer concentration on the carotid arteries, is an attractive alternative to the invasive gold-standard method of arterial cannulation of the radial artery. Nevertheless, most image-derived input function methods still rely on extracting a small number of blood samples to correct for partial volume effects, metabolites and plasma fraction (blood-based). In this work, we assess two non-invasive image-derived input function techniques (blood-free). The two blood-free methods were first applied to a computational phantom and compared with a well established blood-based method. Using image-derived input functions, parametric maps of the binding potential were obtained for [11C]-Raclopride PET images from ongoing studies. These were in turn compared to maps that had been obtained using a reference-region based quantification approach. Although good quantification estimates were found for some subjects, it was hard to guarantee consistency. The biggest obstacle seems to be an underestimation of the spill-out effects, which can be minimized using a small number of venous blood samples.
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