Design and Fabrication of Pneumatically Actuated Valveless Pumps

In this study, a valveless pump was successfully designed and fabricated for the purpose of medium transportation. Different from traditional pumps, the newly designed pump utilizes an actuated or a deflected membrane, and it serves as the function of a check valve at the same time. For achieving the valveless property, an inlet or outlet port positioned in an upper- or lower-layer thin membrane was designed to be connected to an entrance or exit channel. Theoretical analysis and numerical simulation were conducted simultaneously to investigate the large deformation characteristics of the membranes and to determine the proper location of the inlet or outlet port on the proposed pump. Then, the valveless pump was fabricated on the basis of the proposed design. In the experiment, the maximum flow rate of the proposed pump exceeded 12.47 mL/min at a driving frequency of 5.0 Hz and driving pressure of 68.95 kPa.

An optimized 3D-printed perfusion bioreactor for homogeneous cell seeding in bone substitute scaffolds for future chairside applications

A clinical implementation of cell-based bone regeneration in combination with scaffold materials requires the development of efficient, controlled and reproducible seeding procedures and a tailor-made bioreactor design. A perfusion system for efficient, homogeneous, and rapid seeding with human adipogenic stem cells in bone substitute scaffolds was designed. Variants concerning medium inlet and outlet port geometry, i.e. cylindrical or conical diffuser, cell concentration, perfusion mode and perfusion rates were simulated in silico. Cell distribution during perfusion was monitored by dynamic [18F]FDG micro-PET/CT and validated by laser scanning microscopy with three-dimensional image reconstruction. By iterative feedback of the in silico and in vitro experiments, the homogeneity of cell distribution throughout the scaffold was optimized with adjustment of flow rates, cell density and perfusion properties. Finally, a bioreactor with a conical diffusor geometry was developed, that allows a homogeneous cell seeding (hoover coefficient: 0.24) in less than 60 min with an oscillating perfusion mode. During this short period of time, the cells initially adhere within the entire scaffold and stay viable. After two weeks, the formation of several cell layers was observed, which was associated with an osteogenic differentiation process. This newly designed bioreactor may be considered as a prototype for chairside application.

Development of a rat capnoperitoneum phantom to study drug aerosol deposition in the context of anticancer research on peritoneal carcinomatosis

Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC) is a promising approach with a high optimization potential for the treatment of peritoneal carcinomatosis. To study the efficacy of PIPAC and drugs, first rodent cancer models were developed. But inefficient drug aerosol supply and knowledge gaps concerning spatial drug distribution can limit the results based on such models. To study drug aerosol supply/deposition, computed tomography scans of a rat capnoperitoneum were used to deduce a virtual and a physical phantom of the rat capnoperitoneum (RCP). RCP qualification was performed for a specific PIPAC method, where the capnoperitoneum is continuously purged by the drug aerosol. In this context, also in-silico analyses by computational fluid dynamic modelling were conducted on the virtual RCP. The physical RCP was used for ex-vivo granulometric analyses concerning drug deposition. Results of RCP qualification show that aerosol deposition in a continuous purged rat capnoperitoneum depends strongly on the position of the inlet and outlet port. Moreover, it could be shown that the droplet size and charge condition of the drug aerosol define the deposition efficiency. In summary, the developed virtual and physical RCP enables detailed in-silico and ex-vivo analyses on drug supply/deposition in rodents.

Electron Microscopic Confirmation of Anisotropic Pore Characteristics for ECMO Membranes Theoretically Validating the Risk of SARS-CoV-2 Permeation

The objective of this study is to clarify the pore structure of ECMO membranes by using our approach and theoretically validate the risk of SARS-CoV-2 permeation. There has not been any direct evidence for SARS-CoV-2 leakage through the membrane in ECMO support for critically ill COVID-19 patients. The precise pore structure of recent membranes was elucidated by direct microscopic observation for the first time. The three types of membranes, polypropylene, polypropylene coated with thin silicone layer, and polymethylpentene (PMP), have unique pore structures, and the pore structures on the inner and outer surfaces of the membranes are completely different anisotropic structures. From these data, the partition coefficients and intramembrane diffusion coefficients of SARS-CoV-2 were quantified using the membrane transport model. Therefore, SARS-CoV-2 may permeate the membrane wall with the plasma filtration flow or wet lung. The risk of SARS-CoV-2 permeation is completely different due to each anisotropic pore structure. We theoretically demonstrate that SARS-CoV-2 is highly likely to permeate the membrane transporting from the patient’s blood to the gas side, and may diffuse from the gas side outlet port of ECMO leading to the extra-circulatory spread of the SARS-CoV-2 (ECMO infection). Development of a new generation of nanoscale membrane confirmation is proposed for next-generation extracorporeal membrane oxygenator and system with long-term durability is envisaged.

An Apparatus Designed for Coating and Coloration of Filaments Used in Fused Filament Fabrication (FFF) 3D Printing

Background: Three dimensional (3D) printing is emerging technology, capable of manufacturing a solid layer by layer. With the advancements of materials for 3D printing, this technology is applicable in almost every sector. But in accordance with the product requirements we need to modify the mechanical properties of material. To achieve good surface finish we require coating of filament. For this purpose an apparatus is designed for coating of material over a filament, which is capable of coating filaments uniformly and with automated process. Objective: The objective of present invention is directed to a filament feeding device for applying uniform coating on a filament in order to make 3D solid objects with good quality finishing, thereby eliminating the chances of strains and imperfect coating on the filament. Methods: The present invention relates to a filament feeding device, comprising a container equipped within the device for storing a chemical solution in a liquefied form, an inlet port fabricated on the container for inserting a filament inside the container, plurality of relief valves placed at a bottom portion of the container for controlling the leakage of the filaments during insertion of the filaments. A stepper motor in association with a blade equipped within the container to rotate the main extruder of a 3D printer, and an outlet port designed opposite to the inlet port for discharging the filament from the container for 3D printing of the filament in order to manufacture the solid object. Results: The apparatus makes it easy for coating and coloration of materials to make the reinforced composite filaments. As this apparatus provides uniform coating of material on the filaments, the product printed by filaments have good surface finish. Conclusion: The proposed method can reduce coating time and printing time. This work provides meaningful implication to researchers who are doing research in the domain of additive manufacturing.

Simulation of Hydraulic Cylinder Cushioning

The internal cushioning systems of hydraulic linear actuators avoid mechanical shocks at the end of their stroke. The design where the piston with perimeter grooves regulates the flow by standing in front of the outlet port has been investigated. First, a bond graph dynamic model has been developed, including the flow throughout the internal cushion design, characterized in detail by computational fluid-dynamic simulation. Following this, the radial movement of the piston and the fluid-dynamic coefficients, experimentally validated, are integrated into the dynamic model. The registered radial movement is in coherence with the significant drag force estimated in the CFD simulation, generated by the flow through the grooves, where the laminar flow regime predominates. Ultimately, the model aims to predict the behavior of the cushioning during the movement of the arm of an excavator. The analytical model developed predicts the performance of the cushioning system, in coherence with empirical results. There is an optimal behavior, highly influenced by the mechanical stress conditions of the system, subject to a compromise between an increasing section of the grooves and an optimization of the radial gap.

Applicability justification and structural schemes of live fish containers for fish seining, transportation and releasing

Purpose: substantiation and development of structural schemes of live fish containers for fish seining, transporting and releasing, adapted for use in fish traps, which are part of the hydraulic facilities of fish-breeding and fish-breeding-reclamation complexes. Materials and Methods. The experimental base for substantiating the applicability of developing designs for live fish containers for fish traps is made up of survey data of pond and basin fish breeding complexes. The methodological basis for the containers design was formed by technologies and methods of the design theory of new technology. Results. It is shown that the technologies used for seining, transportation and releasing fish stock grown in ponds using permeable (perforated) containers have a negative impact on the physiological state of underyearlings and yearlings of fish, which justifies the applicability of using live fish containers. The requirements for the structures of live fish containers used in fish-catching structures of fish-breeding complexes have been determined. Two competing design schemes of impervious containers with a pneumatic fish release system and a fish outlet port have been proposed. Structurally, containers are made in the form of a prismatic container with impervious sides and a flat bottom. In a container with a pneumatic system, a perforated platform movable by it is provided, which allow ensuring the presence of fish in it and their release into the reservoir depending on its vertical location in the container inner cavity. In the hatch port structure in the bottom of the container, a hatch device is provided with the possibility of moving it to the open and closed positions, the regulation of which allows the fish accumulation, presence and release into the reservoir. Conclusion. As a result of the research carried out, the applicability of using live fish containers was substantiated and two options for their design were proposed.

Fostering Function-Sharing Using Bioinspired Product Architecture

This work deduces principles of bioinspired product architecture to effectively leverage biological function-sharing in engineering design. Function-sharing enables a single structure to perform multiple functions and can improve the performance characteristics of a system. The process of evolution via natural selection has led to the emergence of function-sharing adaptations in biological systems. However, the current practice of bioinspired function-sharing is largely limited to the solution-driven imitation of biological structures. This work aims to overcome such limitations by performing a function-based analysis of biological product architectures. First, a phylogenetic approach is used to select generalized case studies from the animal kingdom. Next, the product architectures of the selected case studies are then modeled using function modeling and analyzed by clustering the identified functions into modules. A function-based categorization of the sampled biological modules reveals the presence of four types of modules in the biological case studies. Analyzing the function-sharing scenarios associated with each type of biological module enables us to deduce four guidelines for bioinspired development and arrangement of function-sharing modules. Finally, a demonstration study applies the guidelines to the design of an inlet–outlet port for a washer–dryer system. The deduced guidelines can enable engineers to identify function-sharing scenarios in the early stages of product design and reduce the need to imitate biological structures for function-sharing.