Rapid Prototyping Techniques Research Articles

Lithography and Etching‐Free Microfabrication of Silicon Carbide on Insulator Using Direct UV Laser Ablation

Silicon carbide (SiC)‐based microsystems are promising alternatives for silicon‐based counterparts in a wide range of applications aiming at conditions of high temperature, high corrosion, and extreme vibration/shock. However, its high resistance to chemical substances makes the fabrication of SiC particularly challenging and less cost‐effective. To date, most SiC micromachining processes require time‐consuming and high‐cost SiC dry‐etching steps followed by metal wet etching, which slows down the prototyping and characterization process of SiC devices. This work presents a lithography and etching‐free microfabrication for 3C‐SiC on insulator‐based microelectromechanical systems (MEMS) devices. In particular, a direct laser ablation technique to replace the conventional lithography and etching processes to form functional SiC devices from 3C‐SiC‐on‐glass wafers is used. Utilizing a single line‐cutting mode, both metal contact shapes and SiC microstructures can be patterned simultaneously with a remarkably fast speed of over 20 cm s−1. As a proof of concept, several SiC microdevices, including temperature sensors, strain sensors, and microheaters, are demonstrated, showing the potential of the proposed technique for rapid and reliable prototyping of SiC‐based MEMS.

Closed Loop Control of Photo Voltaic Emulator Using Fractional Calculus

Threatening environmental effects have forced the community to utilize green and clean alternative options for the generation of electric power. As a matter of fact, solar energy is a critical source of energy; so the demand for creative research is its peak. However, performing real time experiments on solar PV systems is limited by cost, manufacturing, weather constraints and requirement of large space. Thus an equivalent solar energy photo voltaic (PV) system is required for experimental verification and analysis based on precise simulations. In this research work a PV emulator system based on a buck converter is realized. The main objective of PV Emulator is to replicate the characteristic curves (I-V, P-V) of the real solar panel. In order to compensate the variations in both the load and the parameters of power stage, a robust control system is required. A fractional order sliding mode control scheme (FOSMC) has been designed and investigated in this research work. Results have proved the superior performance of the FOSMC as compared to other classical sliding mode control method. The FOSMC controller and PV emulator are implemented using rapid prototyping technique.

Development of a microfluidic flow-focusing droplet generating device utilising rapid prototyping technique

In the recent decades, droplet-based microfluidics has emerged as a promising research area which covers various applications in a broad spectrum of fields such as chemical reactions, drug discovery, molecule synthesis and cell biology. This study proposes the implementation of a microfluidic droplet generating prototype using the popular flow-focusing geometry. The proposed system is fabricated based on a rapid prototyping technique, which significantly simplifies the fabrication process, reduces the production cost and shortens the time-to-market as compared with traditional techniques. The functionalities and characteristics of the prototype were carefully verified by simulations and practical experiments. The obtained results showed that the generation of droplets could be precisely controlled by adjusting the flow rate ratio between the dispersed phase and the continuous phase.

Influential analysis of fused deposition modeling process parameters on the wear behaviour of ABS parts

Fused deposition modelling (FDM) is an additive manufacturing process (AM) that comes under rapid prototyping technique in which parts can be manufactured at a faster rate and even more complex parts can be manufactured with high accuracy at low production cost compared to conventional manufacturing methods. This research work is aimed to provide insight on the dependency of wear properties on various process parameters of the FDM printed acrylonitrile butadiene styrene (ABS) parts. The process parameters considered in this study are layer thickness, infill density and infill pattern. Unidirectional sliding tests were performed with pin on disc wear testing apparatus. It is found that the wear rate and the coefficient of friction of FDM printed parts can be controlled by varying the process parameters to attain the optimal state which is very difficult in conventional methods. Among the three process parameters layer thickness is found to be a dominant one because it is directly proportional to the wear rate. The infill pattern combined with infill density produces rapid variation in wear performance.

3D tissue scaffold library development form medical images for bioprinting application

Computer-Aided Tissue Engineering, rapid prototyping or solid free form fabrication (SFF) technique plays an important role in the development of porous tissue scaffolds for regeneration of cells with appropriate shape, size, and void volume so a specific cells can penetrate and develop in these scaffolds when nutrient is provided. SFF utilizes computer-aided design (CAD) and finite element analysis (FEA) to allow virtual design, characterization, and production of porous scaffold optimized for specific tissue. In this article, we propose an advanced approach for 3D printing using medical image which helps to replicate the various human anatomical structure that can be utilized for synthesis of patient-specific tissue scaffold by applying rapid prototyping (RP) also a Graphical User Interface (GUI) is provided which help end-user to choose the desired anatomical structure. This approach involves the combination of medical images obtained from anatomical structural data through CT (computed tomography)/Magnetic resonance imaging (MRI) in the form of Digital Imaging and Communications in Medicine (DICOM) obtained from online data source, CAD modeling for customized 3D designing the digital porous scaffold models with the help of medical images for different tissue like cardiac, articulating knee cartilage, skin, hepatic, bone etc., that leads to formation of 3D stereolithographic (STL) model and correspondingly development of digital library which can be further applied for patient-specific 3D bioprinting application. With the help of provided technology, a 3D scaffold could be developed on which specific cells are seeded to regenerate the desired tissue/organ. We successfully 3d printed five porous unit scaffolds designed in CAD module four of which is with polylactic acid (PLA) and one with chitosan composite polymer and observed the growth of cartilage on 3D printed chitosan composite scaffold.

Comparision of tribological behaviour for parts fabricated through fused deposition modelling (FDM) process on abs and 20% carbon fibre PLA

Fused deposition modelling (FDM) is a modern rapid prototyping technique which is used colossally for its ability to build applicable components in an equitable time. It is a 3D printing technique where the constituents are printed by supplementing the heated engineering plastic material layer by layer through a print head nozzle. So far engineered thermoplastics like Acrylonitrile Butadiene Styrene (ABS), carbon fibre poly lactic acid (CFPLA), polyamide, etc were used for parts production in this realm. During the itinerary of process engineering plastics may undergo wear because of the real time processing conditions like high pressure, temperature etc. In this experimental investigation a comparative study on tribological properties was performed on parts fabricated by FDM technique for 20% CFPLA and ABS specimens. The process parameters considered in this study are layer thickness, infill pattern and infill density. A series of Pin-on-disc tests by varying normal load and sliding speed, essentially a materials tribology test is used to screen the materials for the tribological properties (wear rate and coefficient of friction). In this study the layer thickness contribute to the wear at a direct proportion because as the thicker one would last long to wear and reach substrate because of its size. The infill pattern is indirectly proportional to the wear rate.

Versatile hybrid acoustic micromixer with demonstration of circulating cell-free DNA extraction from sub-ml plasma samples.

Acoustic micromixers have attracted considerable attention in the last years since they can deliver high mixing efficiencies without the need for movable components. However, their adoption in the academic and industrial microfluidics community has been limited, possibly due to the reduced flexibility and accessibility of previous designs since most of them are application-specific and fabricated with techniques that are expensive, not widely available and difficult to integrate with other manufacturing technologies. In this work, we describe a simple, yet highly versatile, bubble-based micromixer module fabricated with a combination of low-cost rapid prototyping techniques. The hybrid approach enables the integration of the module into practically any substrate and the individual control of multiple micromixers embedded within the same monolithic chip. The module can operate under static and continuous flow conditions showing enhanced mixing capabilities compared to similar devices. We show that the system is capable of performing cell-free DNA extractions from small volumes of blood plasma (≤500 μl) with up to a ten-fold increase in capture efficiency when compared to control methods.

Optimization of micromilled channels for microfluidic applications using gas-blowing-assisted PDMS coating

Micromilling is a flexible, inexpensive and rapid prototyping technique for polymer microfluidic devices. However, the applications of microfluidic devices fabricated by micromilling have been compromised by their poor surface quality. In this study, we demonstrated a gas-blowing-assisted (GBA) polydimethylsiloxane (PDMS) coating that is used to reduce the surface roughness of micromilled channels, yielding optical grade channel walls while simultaneously offering high flexibility in channel dimensions and morphology by controlling the coating parameters. In this method, a thin layer of PDMS is coated on the engraved substrate, and then a computer numerical control (CNC)-guided gas-blowing is used to selectively remove surplus PDMS prepolymer in channels, which results in a thin residual and smooth PDMS coating on the walls of channels. With this GBA PDMS coating, the channel surface roughness of below 8 nm could be achieved without the need of advanced polishing equipment or procedures. Furthermore, this method has the capability to fabricate non-rectangular microchannels with different shapes in cross-section depending on the process parameters, which benefits microvascular research and tissue engineering.

Fused Deposition modeling process parameters optimization and effect on mechanical properties and part quality: Review and reflection on present research

Abstract Additive manufacturing (AM) was developed initially as a technique for rapid prototyping, to visualize, test and authenticate a design, before end-user production of the design. In recent years, Additive Manufacturing (AM) technique Fused Deposition modeling (FDM), has developed to become a rapid manufacturing technique because of the ability to produce complex parts layer-by-layer in lesser production cycle time than as compared to conventional machining processes. FDM also offers the advantage of the lowest cost because of no tooling requirements. Despite these advantages, building parts by utilizing FDM for end-use is still a demanding endeavor. This is because FDM has multiple processing parameters, which affect the part quality, mechanical properties, build time and dimensional accuracy. These FDM processing parameters include air gap, build orientation, infill percentage, raster angle, layer thickness, etc. Depending upon the application, for which the part is manufactured, careful selection of these process parameters needs to be done. For a specific output requirement, some of the process parameters are significant than the rest, these significant process parameters need to be identified and optimized. Due to this, researchers have explored and utilized various experimental or statistical Design of Experiment (DOE) techniques for optimizing the FDM process parameters to improve the mechanical properties or part quality or both. Some of these DOE techniques include the Taguchi method, Genetic algorithm (GA), gray relational, Response surface method (RSM), fractional factorial, Artificial Neural networks (ANN), Fuzzy logic, ANOVA, etc. This article aims at reviewing the current research on the statistical and experimental design techniques for different applications or output responses such as enhancing mechanical properties, build time, part quality, etc.

Hermeticity of a hollow obturator model using CAD and rapid prototyping technologies

Statement of problemAlthough closed hollow obturator prostheses provide the benefit of minimized weight, they also pose challenges. They are complex to fabricate, and contaminated water can easily enter the hollow section through the joined part, making them unsanitary and leading to malodor and increased weight. PurposeThe purpose of this in vitro study was to investigate the hermeticity and durability of a hollow obturator model fabricated by using computer-aided design (CAD) and rapid prototyping (RP) techniques and to evaluate the possibility of its clinical use. Material and methodsLeak testing was used to evaluate the hermeticity and durability of hollow spherical obturator specimens with an outer diameter of 30 mm and 2 different wall thicknesses (1.5 and 2.0 mm). Six specimens were fabricated for each of the wall thicknesses by using CAD and RP techniques. The accumulation of fluids in the hollow obturator specimens was evaluated every day by using megascopic observation with photoirradiation from the base of the specimens. The amount of water absorption and the rate of increase in the weight of the 2 specimens were calculated and compared. Statistical analysis was performed by using the Mann-Whitney U test (α=.05). ResultsThe application of CAD and RP techniques made it possible to fabricate a hollow obturator model specimen with completely unified parts. The 1.5-mm specimen showed an absorption rate (2.61%) that significantly exceeded that of the 2.0-mm specimen (2.53%) on day 130 (P=.006). By the end of the observation period, the 1.5-mm specimen exhibited large amounts of water absorption and destruction. The 1.5-mm-thick wall had reduced hermeticity than the 2.0-mm-thick wall. ConclusionsA fully unified hollow obturator model with 2.0-mm-thick walls was fabricated by using CAD and RP techniques. The absence of any joints prevented fluid accumulation, making this method suitable for the fabrication of hollow prostheses.

Experimental validation of finite element modelling on tibia with osteogenesis imperfecta

The paper aimed to determine the validity of finite element analysis of tibia bone affected by Osteogenesis Imperfecta (OI) under various angle of bowing of the bone. Finite element (FE) model of human tibia bones were developed with various degree of bowing to simulate different severity of OI, and then the geometrical models of these FE models were used to develop bone specimen using fused deposition method (FDM) rapid prototyping technique. Compression tests were conducted to the bone specimen and FE analysis were performed by simulating conditions of the compression test, and then results from the compression test and FE simulation were compared. It have been found that both of the results corresponded to each other, therefore it is concluded that FE analysis is able to simulate the mechanical response of tibia bone with OI.

Optimized commercial desktop cutter technique for rapid-prototyping of microfluidic devices and application to Taylor dispersion.

Microfluidics provides a platform for efficient and transportable microanalysis, catalyzing advancements in fields such as biochemistry, materials science, and microbial ecology. While the analysis is cost-effective, standard device fabrication techniques are disproportionately expensive and specialized. A commercially available desktop cutting plotter provides an accessible method for rapidly fabricating microfluidic devices at extremely low costs. The optimized technique described in the present work enables fabrication of microchannels with dimensions as small as ∼100 μm. Straightness of channel walls is comparable to other common fabrication techniques but achieved here at a fraction of the cost and fabrication time. Solute dispersion experiments are performed using the rapidly prototyped channels to measure the effective dispersion coefficient in laminar flow through rectangular channels. The results of these experiments compare favorably to predictions from classical Taylor-Aris dispersion theory. This note provides all necessary tools for researchers and educators to seamlessly apply the desktop cutter fabrication technique. Materials list, fabrication instructions, and detailed channel characterization results are available in the supplementary material.

Automated Determination of As(III) in Waters with an Electrochemical Sensor Integrated into a Modular Microfluidic System.

The presence of high levels of arsenic in waters poses a threat to the human health in many countries all over the world. Effective surveillance programs of water quality require the implementation of in-field tests to assess early the presence of this metal ion and other contaminants. To date, there exist few market-available analytical approaches that suffer from important limitations related to cost, in addition to complex reactions, very long analysis times, and/or high limits of detection. This work describes a robust electrochemical sensor integrated into a modular microfluidic system that shows a clear potential to be deployed for the on-site monitoring of inorganic As(III) species. Flexible and transparent microfluidic modules are fabricated by rapid prototyping techniques and include different microfluidic components among them, flow cells where electrochemical sensors can be easily and reversibly inserted. The electrochemical sensor comprises a gold nanoparticle (AuNP)-modified gold thin-film electrode that is readily applied to the sensitive detection of As(III) by anodic stripping linear sweep voltammetry. The microfluidic system enables the automatic sensor calibration, sample uptake, and preconditioning as well as As(III) detection. The system response to As(III) is linear in a concentration range of 1-150 μg L-1, with a detection limit of 0.42 μg L-1, which is well below the threshold value of 10 μg L-1 set by the World Health Organization. Analysis of tap water and two water samples from two Argentinean aquifers, spiked with different As(III) concentrations, demonstrates the excellent performance of the system.

3D printing of cordierite honeycomb structures and evaluation of compressive strength under quasi‐static condition

AbstractCeramic honeycombs exhibit unique mechanical properties based on engineered formulations and geometry of cells. Extrusion of formable paste through a complex honeycomb die is the commonly practiced technique for the manufacturing of honeycombs globally. Extrusion die fabrication is a complex process which necessitates sophisticated infrastructure facilities that provide high geometrical accuracy and finish to produce defect free honeycombs. Furthermore, every configuration of honeycomb requires a specific tool. Additive manufacturing (AM)/ 3D printing is a rapid prototyping technique which offers flexibility in fabrication of honeycombs with desired geometries from a virtual model directly. Further, this does not require complicated dies. In this study, viscoplastic printable cordierite raw mix paste with a shear rate exponent of 0.87 was printed into honeycombs with hexagonal, square, and triangular cells using a ram type 3D printer. The printed honeycomb samples are found to possess good integrity and near net shape after drying. Sintered 3D‐printed honeycomb samples of all configurations have exhibited cordierite as a major phase along with minor phases of magnesium aluminate (MgAl2O4) spinel, clinoenstatite (MgSiO3), and corundum (Al2O3) with sintered density of 2.41‐2.48 g/cc. The samples are also subjected to compression testing under quasi‐static condition. The study demonstrates 3D printing as a viable and flexible technique for rapid prototyping of honeycombs with desired configurations and engineered properties.

Modeling and Additive Manufacturing of a Missing Teeth Human Mandible

In biomedical engineering, fiber-reinforced polymers play an important role in creating physical biological models of patients, which helps surgeons explain anatomical details to patients and perform trial operations. Replicating the precise three-dimensional (3D) structure of the human mandible is now a priority for rebuilding these bones for complete functional and aesthetic healing. Additional production methods and reverse engineering are required to achieve the design of a personalized device with precise shape and size. The main purpose of this research work is to develop a specially developed human mandibular biological model using the additive manufacturing method, FDM (Fused Deposition Melting). FDM is performed by loading a CAD model into a 3D Printer. We present this method using the FDM (Fused Deposition Melting) method to generate a human mandible biological model. Data obtained from computed tomography (CT) with a resolution of 1 mm was converted to a 3D model by computer aided design (CAD) using CT digital imaging and medical communication (DICOM) data. After the CAD model is built, it is converted to a stereolithography (*.STL) format and then processed by rapid prototyping techniques to create a physical anatomical model using 3D printing. Converting two-dimensional data (2D) from computed tomography data to a 3D model is an accurate guide to shaping bone grafts. The current approach can translate treatment plans directly into the surgical field. It is an important teaching tool for forming and fixing implants, helping to counsel patients.

How has LCA been applied to 3D printing? A systematic literature review and recommendations for future studies

Abstract Previously perceived as a rapid prototyping technique, additive manufacturing (AM) has evolved into a fully developed manufacturing process, with growing accessibility to different industrial sectors. Its technological and economic advantages are frequently documented, but AM’s environmental performance is seldom investigated. Not long ago discrete initiatives to assess AM’s applicability for building large-scale structures started to arise. Mostly focused on technical and economic feasibility, these studies pave the way for the process’s consolidation in the construction sector. This paper aims to systematically and critically assess the available literature on AM’s life cycle environmental impacts and to identify the main challenges and trends on loads measurements. The findings help feed recommendations to perform life cycle assessments (LCA) in AM initiatives, with a special focus on the construction sector. A systematic search led to the careful analysis of 52 papers, out of 353 that matched our search protocol. In terms of LCA methods’ robustness, a lack of transparency stood out in many papers, suggesting that authors were most likely non-LCA experts, applying the tool without much knowledge of requirements and modelling intricacies. In terms of documented global warming potential (GWP) values in comparison to conventional manufacturing (CM), AM processes were portrayed as beneficial in most cases. Most papers documented results ranges, which represented different printing, production or distribution strategies, in which AM’s performance varied considerably. LCA played a significant role in finding an optimum production approach and seems to be a valuable lens to assure 3D printing’s environmental competitiveness. A contribution analysis showed that there is a shift between materials vs. production processes contribution in the life cycle GWP loads of systems manufactured with AM and CM. 3D printing processes account for almost 80% of AM’s total GWP, while for CM that position is held by the material-related loads. For construction related AM processes, the material intensity is, however, still by far the largest contributor to building systems’ GWP, maintaining the impact distribution as in typical manufacturing processes.

Self-Made Rapid Prototyping Technique for Orbital Floor Reconstruction: Showcases for Technical Description.

Restoring the orbital cavity integrity in orbital floor defects is a challenging issue due to the anatomical complexity of the floor's surface. This is a showcase for technical description of a novel "in house" rapid prototyping protocol aimed to customize implant for orbital floor reconstruction. The authors present 4 cases to show our Computer-aided-design and Computer-aided-manufacturing digital workflow. The system was based on a 3D-printed press that; through a virtually designed mold, was used to conform a patient specific titanium mesh for orbital floor reconstruction. The merging procedure analysis by iPlan Cranial 3.0 (Brainlab, Munich, Germany) highlighted a 0.71 ± 0.23 mm (P <0.05) discrepancy in a point-to-point superimposition between the digital planned reconstruction and the real in vivo result. The authors expect that this technique will reduce operative time and cost however further study and larger series may better define the applicability in everyday surgical practice.

Effect of the build orientation on the mechanical behaviour of polymers by stereolithography

The use of Rapid Prototyping techniques for the production of end-use parts is increasing in rapid manufacturing. The mechanical properties of stereolithography parts become the most important factor restricting its wide application. The mechanical properties of stereolithography parts can be not only influenced by the material characteristics, but also by the parameters of manufacturing. The purpose of this study is to investigate the influences of the build orientation on mechanical properties of stereolithography parts. Specimens were fabricated with different build orientations related to layout (flat or on an edge), axis and build angle. Mechanical testing including tensile, compressive and impact tests on stereolithography specimens were conducted. The results indicated that layout had a significant effect on tensile and impact properties, and the axis had no significant effect on tensile and impact properties. Also, build angles play an important factor in the compressive strength. From these results, it appears that related characteristics of layer interface have a significant influence on mechanical properties of stereolithography specimens.

Realization of Microfluidic Paper-Based Analytical Devices Using a 3-D Printer: Characterization and Optimization

Microfluidic paper-based analytical devices ( $\mu $ PADs) are a clean-room free, cost-effective, and self-pumping flow-based rapid prototyping technique, which is compatible with a varying range of fluids. Until now, $\mu $ PADs have been primarily fabricated using crayons, and plotting-machine and solid-ink printers. These devices can be easily employed for various detection schemes, such as electrical, electrochemical, and optical. The presence of a capillary effect in the chromatograph paper has made $\mu $ PADs independent of a passive device, such as pumps and valves. In this paper, an alternative and a novel method is proposed to achieve the $\mu $ PADs effortlessly using a 3-D printer (3DP), which has many advantages over the existing methods. For creating hydrophobic barriers for microchannel walls, polycaprolactone (PCL) filament was used with fused-deposition modeling (FDM) 3DP. PCL filaments were deposited on the chromatography paper followed by heating for determining the overall dimension and depth of the microchannel at which PCL melts and penetrates into this paper. The $\mu $ PADs are characterized and optimized for two parameters. First, fabrication parameters, such as heating temperature and time duration, were used for the creation of the hydrophobic barrier using a hot air oven. Second, the microchannel parameters, such as microchannel width, boundary thickness, chromatography paper grade, and microchannel source shape (rectangular, triangular, and circular) were used for the fluid-flow by measuring the time taken by fluid to travel a fixed length of the microchannel. After rigorous analysis, it was found that for the creation of the hydrophobic barrier, $\mu $ PADs heated between temperature 120°C to 150°C require 30 min. Under optimized conditions for the fluid flow, the chromatography paper grade 1441 with a triangular source microchannel was found to be best. This paper provides an alternate, simple, and optimized method toward the development of the application-specific $\mu $ PADs, such as the micro-viscometer, which, in turn, can be widely used to monitor various types of fluids including human bodily fluids.

136. Biomechanical study of the sacral replacement part as a model for spinopelvic reconstruction following total sacrectomy

BACKGROUND CONTEXT Total sacrectomy is usually performed when a sacral tumor involves high-level sacral vertebra. Following total sacrectomy, the continuity between the spine and pelvis is necessary for ambulation, and to enable patients to resume daily living activities sooner during rehabilitation. PURPOSE The aim of this study is to assess the biomechanical properties of a novel spinopelvic reconstruction system following total sacrectomy: a sacral solid porous titanium replacement part manufactured through a rapid prototyping technique (EBM, electron beam melting). STUDY DESIGN/SETTING Biomechanic study. METHODS Three studies were carried out: with finite element methods (FEM), fatigue with a polyamide model, and in cadaver. The following models were compared in the FEM study: (1) two connected rods in L, L3-L5 pedicle screws, and two bilateral iliac screws; (2) Model 1 with no L3 fixation; (3) two connected rods in L, two screws to the L5 body and L3-L5 pedicle screws; (4) Model 3 with no L3 fixation; (5) sacral replacement part connected to the L5 body with two screws and two bilateral iliac screws, pedicle screws in L4-L5, and two vertical rods that connect them to the part; (6) Model 5 with a trans-iliac fixation rod. The L5 (mm) vertical drop, the Von Mises stress (Nm), and stress distribution were assessed. In the other studies, Model 5 was evaluated, checking the existence of errors in the instrumentation. RESULTS The areas of maximum stress were located in the connection between L5 and the pelvis in all the models. No errors were detected in the fatigue with a polyamide model studies nor in cadaver. CONCLUSIONS Significant reductions of tension and vertical displacements were achieved with the sacral replacement part as well as the lowest values published to date; this indicates that the assembly is rigid and stable, preventing the collapse of the spine on the pelvis. With the tensions obtained with the replacement part–112 MPa there is no risk of breaking when exposed to static loads nor fatigue behavior of the implants, as opposed to the other assessed and published models. Once implanted, the replacement part could show good behavior by reconstructing the anterior spine, preventing overloads in the spine or pelvis, increasing fusion rates, potentially reducing the number of check-up surgeries due to instrumental breaking down, and allowing early mobilization of the patient. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.