Rapid prototyping, tectoRNA, ribosomal RNA, stereolithography, selective laser sintering, powder-binder printing, fused deposition modeling, RNA structure, van der waals radius, covalent radius, Z-Corporation, Stratasys Corporation, RNA motifs, and C-loop
The application of rapid prototyping (RP) to the field of molecular modeling is growing due to the availability of computer programs and RP machines at major research institutions. Two RP techniques that are applicable to the study are powder-binder printing and Fused Deposition Modeling (FDM). Both of these technologies are available at BGSU and can be used in order to study the basepair interactions in many different types of RNA motifs. I have determined that the powder-binder technique is preferred when the tertiary structure of RNA is desired; conversely, FDM is better when the primary and secondary structures of RNA motifs are desired. By using FDM modeling, you can see the orientation of non-canonical basepairs, hydrogen bonds between atoms, the phosphate- sugar backbone, as well as structural motifs in RNA. I then applied our knowledge of RP technology by creating physical models of the C-loop motif, RNase P RNA, the kink-turn, the sarcin-ricin loop, and the SARS virus genome.
Stereolithography, Oxygen inhibition, Microlenses, Process planning, Microfabrication, Microlithography, Microstructure, and Rapid prototyping
A novel approach to microfabrication based on stereolithography was presented. This fabrication process is referred to as, ‘Exposure Controlled Projection Lithography’ (ECPL). In the ECPL process, incident radiation, patterned by a dynamic mask, passes through a transparent substrate to cure photopolymer resin. By controlling the amount of exposure, the height field of the cured film can be controlled. An ECPL system was designed and assembled. Factors affecting the accuracy of the ECPL process in fabricating micron shaped features were identified and studied. A real-time in-situ photopolymerization monitoring system was designed and assembled within the ECPL system to identify the sources of variations present in the system. Parts are fabricated from the ECPL process because of polymerization (or cross-linking) of monomer resin using light energy. Photopolymerization is a complex process involving coupling between several phenomena. This process was modeled by utilizing an understanding of the known polymerization reaction kinetics with incorporating the effects of oxygen inhibition and diffusion. A material response model and a simulation tool to estimate the shape of a cured part resulting from photopolymerization was created. This model was used to formulate a process-planning method to estimate the manufacturing process inputs required to cure a part of desired shape and dimensions. The process planning method was validated through simulations and experiments.
Patient-specific modeling, Congenital heart disease, Cardiovascular fluid dynamics, Segmentation, Image processing, Phase contrast magnetic resonance imaging, Computer-aided design, Rapid prototyping, Stereolithography, Particle image velocimetry, Congenital heart disease, Magnetic resonance imaging, Fluid dynamics, Hemodynamics, and Surgery
Background: Single ventricle congenital heart defects with cyanotic mixing betweensystemic and pulmonary circulations afflict 2 per 1000 live births. Following the atriopulmonaryconnection proposed by Fontan and Baudet in 1971, the present procedure is thetotal cavopulmonary connection (TCPC), where the superior vena cava (SVC) and inferiorvena cava (IVC) are sutured to the left pulmonary artery (LPA) and right pulmonaryartery (RPA). However, surgeon preference dictates the implementation of the extra-cardiacand intra-atrial varieties of the TCPC. Overall efficiency and hemodynamic advantage of thecompeting methodologies have not been determined. Hypothesis: It is hypothesized thatan understanding of the experimental fluid dynamic differences between various Fontansurgical methodologies in the TCPC allows for power loss evaluation toward improved surgicalplanning and design. Methods: Toward such analysis, a previously developed dataprocessing methodology is applied to create an anatomic database of single ventricle patientsfrom in vivo magnetic resonance imaging (MRI) to examine the gamut of TCPCanatomies. From stereolithographic models of representative cases, pressure and flow dataare used to quantify control volume power loss to measure overall efficiency. particle imagevelocimetry (PIV) is employed to detail flow structures in the vasculature. Results arevalidated with dye injection flow visualization and 3-D phase contrast magnetic resonanceimaging (PC-MRI) velocimetry, highlighting flow phenomena that cannot be captured within vivo MRI due to prohibitively long scanning times. Preliminary results illustrate thevariation of control volume power loss over several TCPC anatomies with varying flowconditions, the application of PIV, and validation approaches with 3-D PC-MRI velocimetry.Data from control volume power loss evaluation demonstrate a correlation with TCPCanatomy, providing added clinical knowledge of optimal TCPC design. Findings from PIVand 3-D PC-MRI velocimetry reveal a means for quantitatively comparing flow structure.Dye injection flow visualization offers qualitative insight into limitations of the selected velocimetry techniques.
Energy minimization, Kinematics structure, Deformation, Haptic, Cartesian coordinates, Digital Clay, Stereolithography, Rapid prototyping, Touch, Human-computer interaction Technological innovations, and Kinematics
Digital Clay represents a new type of 3-D human-computer interface device that enables tactile and haptic interactions. The Digital Clay kinematics structure is computer controlled and can be commanded to acquire a wide variety of desired shapes (shape display), or be deformed by the user in a manner similar to that of real clay (shape editing). The design of the structure went through various modifications where we finally settled on a crust matrix of spherical joint unit cells. After designing the kinematics structure, the next step is predicting the deformation of the crust matrix based upon a handful of inputs. One possible solution for predicting the shape outcome is considering minimizing the potential energy of the system. In this thesis two methods will be introduced. The first method will be an abstract model of the crust where the energy is calculated from a simplified model with one type of angular springs. The second method is the actual manufacturable crust model with two types of angular springs. From the implementation of these two methods, the output will be center-points of the unit cells. From the center-points, one can also calculate the joint angles within each unit cell.
This research concentrates on both design and manufacturing methodologies for the implementation of stereolithography (SLA) to produce well controlled, custom designed, porous scaffolds in the biodegradable, biocompatible polymer, poly(propylene fumarate) for both in vitro and in vivo studies. Initially, proof of concept trials were undertaken in a custom designed build tank retro-fitted to a standard SLA 250/40 SLA machine to determine stereolithography process feasibility. The results of the initial trials enabled the build process to be scaled-up and implemented on a dedicated Viper Si2 SLA machine. Poly(propylene fumarate) (PPF) and diethyl fumarate (DEF) ratios were adjusted to improve scaffold build quality, which is particularly important for the control of porosity when manufacturing porous scaffolds. Design methodologies are developed that allow three-dimensional porous volumes to be created using hexagonal and plate and post unit cells. Porous scaffolds were designed using this approach by populating a three-dimensional volume from which the scaffold was produced. Two porous scaffold designs were created for an in vitro cell attachment study and for an in vivo toxicity study using a rat dorsal flap animal model. A further set of in vivo animal studies (dog, rat, and rabbit) motivated the design of custom specific porous scaffolds for each animal model. The scaffold designs were based on three-dimensional, computer tomography scan data which was translated and imported into a 3D computer aided design (CAD) environment for the design of porosity to suit each custom scaffold. The CAD data was used to control the SLA process, finally resulting in poly(propylene fumarate), custom porous sterilizable and implantable scaffolds. The preliminary results from the in vitro and in vivo studies are encouraging. This work represents an advancement of knowledge and capability in the design and manufacture of custom porous scaffolds and provides a guide for further research towards the goal of repairing critical-sized cranial defects and other bony defects using tissue engineering technology.
This thesis aims to investigate the use of additive manufacturing (AM) as a novel manufacturing process for the production of milli-scale chemical reaction systems. Five well developed additive manufacturing techniques; stereolithography (SL), selective laser melting (SLM), fused deposition modelling (FDM), ultrasonic additive manufacture (UAM) and selective laser sintering (SLS) were used to manufacture a number of miniaturised flow devices which were tested using a range of organic and inorganic reactions. SL was used to manufacture a range of functioning milli-scale flow devices from Accura 60 photoresin, with both simple and complex internal channel networks. These devices were used to perform a range of organic and inorganic reactions, including aldehyde and ketone functional group interconversions. Conversion of products within these reactors, were shown to be comparable to commercially available milli-scale coil reactors. More complex designs, which allowed SL parts to be integrated to existing flow and analytical instrumentation, allowed us to develop an automated reaction analysis and optimisation platform. This platform allowed precise control over the reaction conditions, including flow rate, temperature and reagent composition. We also designed a simplex type reaction optimisation software package that could input data in the form of reaction conversions, peak intensities, and thermocouple data, and generate a new set of optimal reaction conditions. SL parts which incorporated embedded analytical components were also manufactured, which allowed us to perform inline reaction analysis as a feedback method for input into the optimisation platform. Stereolithography was shown to be a highly versatile manufacturing method for designing and producing these flow devices, however the process was shown to be still limited by the range of processable materials currently commercially available. SLM was also used to manufacture a number of functioning milli-scale flow devices from stainless steel and titanium, which had simplistic internal channel designs of diameters ranging from 1 to 3 mm. Again, SLM parts were manufactured which incorporated embedded analytical components, which could be integrated into an automated reaction platform. These devices, unlike parts produced via SL, could be attached to heating platforms to allow us to perform high temperature reactions. This control over the reaction temperature formed an essential part of the reaction optimisation platform. These parts were again used to perform a ketone functional group interconversion. Internal structures of these SLM parts were also visualised via micro computed tomography (μCT or microCT) scanning as well as optical microscopy. FDM was used throughout the project as an inexpensive method of prototyping parts which were to be manufactured via more expensive manufacturing processes. This prototyping allowed the optimisation of intricate design features, such as the manufacture of an inline spectroscopic flow cell for integration with a commercially available LC system. FDM was also proposed as a customisable approach to designing and manufacturing flow devices with embedded components, however the current limitations in build resolution and materials choices severely limited the use of FDM for this application. UAM was also proposed as a novel manufacturing process whereby the build process would allow discrete components to be embedded directly into a flow channel. This was demonstrated by embedding a type-k thermocouple across a 2 mm channel. The data from this thermocouple was monitored during a heated reaction, and used as a method of determining the exact reaction conditions the reaction medium was being exposed to. SLS was also proposed as a possible manufacturing method for milli-scale flow devices, however it proved difficult to remove un-sintered powder from parts with internal channel diameters as high as 5 mm. It was shown that this powder was forming a dense semi solid, due to the large degree of shrinkage upon cooling of the SLS parts, which was compressing the powder. More research into optimum processing conditions is required before SLS could be used for the production of intricate channel networks.