Bio-Design and Manufacturing最新文献

Additive manufacturing (AM) has revolutionized the design and manufacturing of patient-specific, three-dimensional (3D), complex porous structures known as scaffolds for tissue engineering applications. The use of advanced image acquisition techniques, image processing, and computer-aided design methods has enabled the precise design and additive manufacturing of anatomically correct and patient-specific implants and scaffolds. However, these sophisticated techniques can be time-consuming, labor-intensive, and expensive. Moreover, the necessary imaging and manufacturing equipment may not be readily available when urgent treatment is needed for trauma patients. In this study, a novel design and AM methods are proposed for the development of modular and customizable scaffold blocks that can be adapted to fit the bone defect area of a patient. These modular scaffold blocks can be combined to quickly form any patient-specific scaffold directly from two-dimensional (2D) medical images when the surgeon lacks access to a 3D printer or cannot wait for lengthy 3D imaging, modeling, and 3D printing during surgery. The proposed method begins with developing a bone surface-modeling algorithm that reconstructs a model of the patient’s bone from 2D medical image measurements without the need for expensive 3D medical imaging or segmentation. This algorithm can generate both patient-specific and average bone models. Additionally, a biomimetic continuous path planning method is developed for the additive manufacturing of scaffolds, allowing porous scaffold blocks with the desired biomechanical properties to be manufactured directly from 2D data or images. The algorithms are implemented, and the designed scaffold blocks are 3D printed using an extrusion-based AM process. Guidelines and instructions are also provided to assist surgeons in assembling scaffold blocks for the self-repair of patient-specific large bone defects.

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Sodium alginate (SA)/chitosan (CH) polyelectrolyte scaffold is a suitable substrate for tissue-engineering application. The present study deals with further improvement in the tensile strength and biological properties of this type of scaffold to make it a potential template for bone-tissue regeneration. We experimented with adding 0%–15% (volume fraction) gelatin (GE), a protein-based biopolymer known to promote cell adhesion, proliferation, and differentiation. The resulting tri-polymer complex was used as bioink to fabricate SA/CH/GE matrices by three-dimensional (3D) printing. Morphological studies using scanning electron microscopy revealed the microfibrous porous architecture of all the structures, which had a pore size range of 383–419 µm. X-ray diffraction and Fourier-transform infrared spectroscopy analyses revealed the amorphous nature of the scaffold and the strong electrostatic interactions among the functional groups of the polymers, thereby forming polyelectrolyte complexes which were found to improve mechanical properties and structural stability. The scaffolds exhibited a desirable degradation rate, controlled swelling, and hydrophilic characteristics which are favorable for bone-tissue engineering. The tensile strength improved from (386±15) to (693±15) kPa due to the increased stiffness of SA/CH scaffolds upon addition of gelatin. The enhanced protein adsorption and in vitro bioactivity (forming an apatite layer) confirmed the ability of the SA/CH/GE scaffold to offer higher cellular adhesion and a bone-like environment to cells during the process of tissue regeneration. In vitro biological evaluation including the MTT assay, confocal microscopy analysis, and alizarin red S assay showed a significant increase in cell attachment, cell viability, and cell proliferation, which further improved biomineralization over the scaffold surface. In addition, SA/CH containing 15% gelatin designated as SA/CH/GE₁₅ showed superior performance to the other fabricated 3D structures, demonstrating its potential for use in bone-tissue engineering.

Galloping cheetahs, climbing mountain goats, and load hauling horses all show desirable locomotion capability, which motivates the development of quadruped robots. Among various quadruped robots, hydraulically driven quadruped robots show great potential in unstructured environments due to their discrete landing positions and large payloads. As the most critical movement unit of a quadruped robot, the limb leg unit (LLU) directly affects movement speed and reliability, and requires a compact and lightweight design. Inspired by the dexterous skeleton–muscle systems of cheetahs and humans, this paper proposes a highly integrated bionic actuator system for a better dynamic performance of an LLU. We propose that a cylinder barrel with multiple element interfaces and internal smooth channels is realized using metal additive manufacturing, and hybrid lattice structures are introduced into the lightweight design of the piston rod. In addition, additive manufacturing and topology optimization are incorporated to reduce the redundant material of the structural parts of the LLU. The mechanical properties of the actuator system are verified by numerical simulation and experiments, and the power density of the actuators is far greater than that of cheetah muscle. The mass of the optimized LLU is reduced by 24.5%, and the optimized LLU shows better response time performance when given a step signal, and presents a good trajectory tracking ability with the increase in motion frequency.

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Based on the building principle of additive manufacturing, printing orientation mainly determines the tribological properties of joint prostheses. In this study, we created a polyether-ether-ketone (PEEK) joint prosthesis using fused filament fabrication and investigated the effects of printing orientation on its tribological properties using a pin-on-plate tribometer in 25% newborn calf serum. An ultrahigh molecular weight polyethylene transfer film is formed on the surface of PEEK due to the mechanical capture of wear debris by the 3D-printed groove morphology, which is significantly impacted by the printing orientation of PEEK. When the printing orientation was parallel to the sliding direction of friction, the number and size of the transfer film increased due to higher steady stress. This transfer film protected the matrix and reduced the friction coefficient and wear rate of friction pairs by 39.13% and 74.33%, respectively. Furthermore, our findings provide a novel perspective regarding the role of printing orientation in designing knee prostheses, facilitating its practical applications.

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On-demand droplet sorting is extensively applied for the efficient manipulation and genome-wide analysis of individual cells. However, state-of-the-art microfluidic chips for droplet sorting still suffer from low sorting speeds, sample loss, and labor-intensive preparation procedures. Here, we demonstrate the development of a novel microfluidic chip that integrates droplet generation, on-demand electrostatic droplet charging, and high-throughput sorting. The charging electrode is a copper wire buried above the nozzle of the microchannel, and the deflecting electrode is the phosphate buffered saline in the microchannel, which greatly simplifies the structure and fabrication process of the chip. Moreover, this chip is capable of high-frequency droplet generation and sorting, with a frequency of 11.757 kHz in the drop state. The chip completes the selective charging process via electrostatic induction during droplet generation. On-demand charged microdroplets can arbitrarily move to specific exit channels in a three-dimensional (3D)-deflected electric field, which can be controlled according to user requirements, and the flux of droplet deflection is thereby significantly enhanced. Furthermore, a lossless modification strategy is presented to improve the accuracy of droplet deflection or harvest rate from 97.49% to 99.38% by monitoring the frequency of droplet generation in real time and feeding it back to the charging signal. This chip has great potential for quantitative processing and analysis of single cells for elucidating cell-to-cell variations.

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