Luzio de Melo, Paulo, da Silva, Miguel Tavares, Martins, Jorge, and Newman, Dava
Artificial Organs. May 2015, Vol. 39 Issue 5, E56, 11 p.
Semiconductor device, Circuit components, and Rapid prototyping
Byline: Paulo Luzio de Melo,Miguel Tavares da Silva, Jorge Martins, Dava Newman Keywords: Functional electrical stimulation; Neuroprosthesis; Arduino microcontroller platform; Accelerometer; Inertial measurement unit; Gait; Force sensitive resistors; Closed-loop control; Drop foot; Rapid prototyping Abstract Functional electrical stimulation (FES) has been used over the last decades as a method to rehabilitate lost motor functions of individuals with spinal cord injury, multiple sclerosis, and post-stroke hemiparesis. Within this field, researchers in need of developing FES-based control solutions for specific disabilities often have to choose between either the acquisition and integration of high-performance industry-level systems, which are rather expensive and hardly portable, or develop custom-made portable solutions, which despite their lower cost, usually require expert-level electronic skills. Here, a flexible low-cost microcontroller-based platform for rapid prototyping of FES neuroprostheses is presented, designed for reduced execution complexity, development time, and production cost. For this reason, the Arduino open-source microcontroller platform was used, together with off-the-shelf components whenever possible. The developed system enables the rapid deployment of portable FES-based gait neuroprostheses, being flexible enough to allow simple open-loop strategies but also more complex closed-loop solutions. The system is based on a modular architecture that allows the development of optimized solutions depending on the desired FES applications, even though the design and testing of the platform were focused toward drop foot correction. The flexibility of the system was demonstrated using two algorithms targeting drop foot condition within different experimental setups. Successful bench testing of the device in healthy subjects demonstrated these neuroprosthesis platform capabilities to correct drop foot.
Nuclear energy -- Production processes, Nuclear power plants -- Production processes, Biological products -- Production processes, Implants, Artificial -- Production processes, Prosthesis -- Production processes, Rapid prototyping, Computer-aided design, Tissue engineering, Stem cell research, Stem cells, Education parks, and School facilities
Knoops, Paul G.M., Biglino, Giovanni, Hughes, Alun D., Parker, Kim H., Xu, Linzhang, Schievano, Silvia, and Torii, Ryo
Artificial Organs. July 2017, Vol. 41 Issue 7, p637, 10 p.
Company legal issue, 3D printing -- Investigations, and Pulmonary hypertension -- Investigations
Byline: Paul G.M. Knoops, Giovanni Biglino, Alun D. Hughes, Kim H. Parker, Linzhang Xu, Silvia Schievano, Ryo Torii Keywords: Mock circulatory system; -Pulmonary artery; -3D printing; -Wave intensity analysis Abstract A realistic mock circulatory system (MCS) could be a valuable in vitro testbed to study human circulatory hemodynamics. The objective of this study was to design a MCS replicating the pulmonary arterial circulation, incorporating an anatomically representative arterial model suitable for testing clinically relevant scenarios. A second objective of the study was to ensure the system's compatibility with magnetic resonance imaging (MRI) for additional measurements. A latex pulmonary arterial model with two generations of bifurcations was manufactured starting from a 3D-printed mold reconstructed from patient data. The model was incorporated into a MCS for in vitro hydrodynamic measurements. The setup was tested under physiological pulsatile flow conditions and results were evaluated using wave intensity analysis (WIA) to investigate waves traveling in the arterial system. Increased pulmonary vascular resistance (IPVR) was simulated as an example of one pathological scenario. Flow split between right and left pulmonary artery was found to be realistic (54 and 46%, respectively). No substantial difference in pressure waveform was observed throughout the various generations of bifurcations. Based on WIA, three main waves were identified in the main pulmonary artery (MPA), that is, forward compression wave, backward compression wave, and forward expansion wave. For IPVR, a rise in mean pressure was recorded in the MPA, within the clinical range of pulmonary arterial hypertension. The feasibility of using the MCS in the MRI scanner was demonstrated with the MCS running 2 h consecutively while acquiring preliminary MRI data. This study shows the development and verification of a pulmonary MCS, including an anatomically correct, compliant latex phantom. The setup can be useful to explore a wide range of hemodynamic questions, including the development of patient- and pathology-specific models, considering the ease and low cost of producing rapid prototyping molds, and the versatility of the setup for invasive and noninvasive (i.e., MRI) measurements.
Byline: Tim A.S. Kaufmann, Shaun D. Gregory, Martin R. Busen, Geoff D. Tansley, Ulrich Steinseifer Keywords: Computational fluid dynamics; Lumped parameter; Mock circulation loops; Validation; Cannulation; Ventricular assist devices Abstract It has been shown that left ventricular assist devices (LVADs) increase the survival rate in end-stage heart failure patients. However, there is an ongoing demand for an increased quality of life, fewer adverse events, and more physiological devices. These challenges necessitate new approaches during the design process. In this study, computational fluid dynamics (CFD), lumped parameter (LP) modeling, mock circulatory loops (MCLs), and particle image velocimetry (PIV) are combined to develop a numerical Pump Testing Framework (nPTF) capable of analyzing local flow patterns and the systemic response of LVADs. The nPTF was created by connecting a CFD model of the aortic arch, including an LVAD outflow graft to an LP model of the circulatory system. Based on the same geometry, a three-dimensional silicone model was crafted using rapid prototyping and connected to an MCL. PIV studies of this setup were performed to validate the local flow fields (PIV) and the systemic response (MCL) of the nPTF. After validation, different outflow graft positions were compared using the nPTF. Both the numerical and the experimental setup were able to generate physiological responses by adjusting resistances and systemic compliance, with mean aortic pressures of 72.2-132.6mmHg for rotational speeds of 2200-3050rpm. During LVAD support, an average flow to the distal branches (cerebral and subclavian) of 24% was found in the experiments and the nPTF. The flow fields from PIV and CFD were in good agreement. Numerical and experimental tools were combined to develop and validate the nPTF, which can be used to analyze local flow fields and the systemic response of LVADs during the design process. This allows analysis of physiological control parameters at early development stages and may, therefore, help to improve patient outcomes. Article Note: Presented in part at the 21st Congress of the International Society for Rotary Blood Pumps, held September 26-28, 2013, in Yokohama, Japan.
Leme, Juliana, Silva, Cibele, Fonseca, Jeison, Silva, Bruno Utiyama, Uebelhart, Beatriz, Biscegli, Jose F., and Andrade, Aron
Artificial Organs. Nov 2013, Vol. 37 Issue 11, p942, 4 p.
Biological products -- Analysis
Byline: Juliana Leme, Cibele Silva, Jeison Fonseca, Bruno Utiyama Silva, Beatriz Uebelhart, Jose F. Biscegli, Aron Andrade Keywords: Blood pump; Centrifugal pump; Temporary ventricular assist device Abstract A new model of centrifugal blood pump for temporary ventricular assist devices has been developed and evaluated. The design of the device is based on centrifugal pumping principles and the usage of ceramic bearings, resulting in a pump with reduced priming (35[+ or -]2mL) that can be applied for up to 30 days. Computational fluid dynamic (CFD) analysis is an efficient tool to optimize flow path geometry, maximize hydraulic performance, and minimize shear stress, consequently decreasing hemolysis. Initial studies were conducted by analyzing flow behavior with different impellers, aiming to determine the best impeller design. After CFD studies, rapid prototyping technology was used for production of pump prototypes with three different impellers. In vitro experiments were performed with those prototypes, using a mock loop system composed of Tygon tubes, oxygenator, digital flow meter, pressure monitor, electronic driver, and adjustable clamp for flow control, filled with a solution (1/3 water, 1/3 glycerin, 1/3 alcohol) simulating blood viscosity and density. Flow-versus-pressure curves were obtained for rotational speeds of 1000, 1500, 2000, 2500, and 3000rpm. As the next step, the CFD analysis and hydrodynamic performance results will be compared with the results of flow visualization studies and hemolysis tests. Article Note: Presented in part at the 7th Latin American Congress of Artificial Organs and Biomaterials held August 22-25, 2012 in Natal, Brazil.
Silva, Andre Fellipe Cavalcante, Santos, Alexsandro Jose Virginio, Souto, Cicero da Rocha, Araujo, Carlos Jose, and Silva, Simplicio Arnaud
Artificial Organs. Nov 2013, Vol. 37 Issue 11, p965, 8 p.
Biological products, Acrylonitrile, Butadiene, and Shape-memory alloys
This paper presents the design and testing of an artificial finger based partly on biomechanics. The prototype was manufactured in acrylonitrile butadiene styrene plastic using a rapid prototyping three-dimensional printer. The flexing of the finger was realized by Ni-Ti shape-memory alloy (SMA) wires with diameters of 0.3mm, activated by resistive heating. The results obtained show the new prototype to be superior in performance, mainly in terms of angles of rotation of the phalanges, compared with some SMA fingers discussed in the literature.