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Abstract  This paper presents a novel bio-microelectrode structure for deep-brain stimulation in neural disorder treatment and a method for connecting PtIr10 microwires onto this microelectrode. The microelectrode is consisted of four stimulation sites fabricated by microfabrication process and two recording sites formed by encapsulation technique. After Si-based microelectrode is fabricated through microfabrication process, electroplating is used to connect microwires to the microelectrode through a Pt film electroplated on the microwires that is fixed in the grooves of the microelectrode. Scanning electron microscopy revealed that the microwire was connected tightly to the microelectrode by electroplating, and the tensile strength of the microwire connection reached up to 0.375 MPa when the thickness of the Pt film was 3 μm and above. Cyclic voltammograms showed that the microelectrode and the electroplated connection had fine electrochemical stability. The results indicated that the electroplating could be used as an effective method for connecting PtIr10 microwires with Pt film microelectrode in deep-brain stimulation. [ABSTRACT FROM AUTHOR]

Background: This study aims to analyze the influencing factors of postoperative Low Anterior Resection Syndrome (LARS) in patients with middle and low rectal cancer who underwent robotic surgery. It also seeks to predict the probability of LARS through a visual, quantitative, and graphical nomogram. This approach is expected to lower the risk of postoperative LARS in these patients and improve their quality of life through effective prevention and early intervention. Patients and methods: This research involved patients with middle and low rectal cancer who underwent robotic surgery in the Department of Gastrointestinal Surgery at the First Affiliated Hospital of Nanchang University from January 2015 to October 2022. A series of intestinal dysfunction symptoms arising from postoperative rectal cancer were diagnosed and graded using LARS scoring criteria. After the initial screening of all variables related to LARS with Lasso regression, they were included in logistic regression for further univariate and multivariate analysis to identify independent risk factors for LARS. A prediction model was then constructed. Results: The study included 358 patients. The parameters identified by Lasso regression included obstruction, BMI, tumor localization, maximum tumor diameter, AJCC stage, stoma, neoadjuvant therapy (NAT), and postoperative adjuvant therapy (AT). Univariate and multivariate analyses indicated that a higher BMI, lower tumor localization, higher AJCC stage, neoadjuvant therapy, and postoperative adjuvant therapy were independent risk factors for total LARS. The AUC of the prediction nomogram was 0.834, with a sensitivity of 0.825 and specificity of 0.741. The calibration curve demonstrated excellent concordance with the nomogram, indicating the prediction curve fit the diagonal well. Conclusion: Higher BMI, lower tumor localization, higher AJCC stage, neoadjuvant therapy, and adjuvant therapy were identified as independent risk factors for total LARS. A new predictive nomogram for postoperative LARS in patients with middle and low rectal cancer undergoing robotic surgery was developed, proving to be stable and reliable. This tool will assist clinicians in managing the postoperative treatment of these patients, facilitating better clinical decision-making and maximizing patient benefits. [ABSTRACT FROM AUTHOR]

A Ti/β-TCP composite porous scaffold with a hierarchical pore structure composed of 3D printed interconnected macroscopic pores and sintered microscopic pores was prepared by direct ink writing (DIW) 3D printing technology. This method can control the extrusion of composite ink at room temperature and produce a 3D scaffold using layer-by-layer deposition. We studied the effects of the β-TCP powder particle size, β-TCP/Ti powder ratio and solid loading on the rheological properties of the ink and optimised the DIW printing process parameters. After sintering, the compressive strength and elastic modulus of the composite scaffold reached 45 MPa and 1 GPa, which is close to the strength of human cancellous bone. The cell culture experiment confirmed that the composite scaffold had better biological properties than the pure titanium scaffold. The composite scaffold has satisfactory mechanical and biological properties, meeting the requirements for orthopaedic implants. [ABSTRACT FROM AUTHOR]

A porous chitosan-gelatin scaffold with specific geometry and complex internal microarchitectures was fabricated via a novel indirect rapid prototyping technique. A stereolithography (SL) technique was employed to build the resin mold, based on which a high-resolution poly-dimethylsilicone (PDMS) mold was microreplicated. The chitosan-gelatin hybrid solution was cast on the PDMS mold for pre-freezing and the monolayer scaffold with predefined features and highly porous structures was produced upon lyophilization. These monolayer structures along with the special interface layers can be stacked together to form a three-dimensional (3D) scaffold. The morphologies of the predefined features maintain well during the assembly process. Hepatocyte culture experiment indicates that the novel microstructured chitosan-gelatin porous scaffold could facilitate cells to migrate and proliferate into the deep layers of the scaffold in comparison with the traditional porous only scaffold. This approach provides a new way to fabricate a complex 3D scaffold using various natural biomaterials for vital organ engineering. [ABSTRACT FROM AUTHOR]

Abstract: The fabrication process for a novel three-dimensional (3D) chitosan/gelatin scaffold with predefined multilevel internal architectures and highly porous structures is presented combining solid freeform fabrication (SFF), microreplication and lyophilization techniques. The computer model of the scaffold is designed with biological data such as branching angle in liver vascular cast incorporated. Stereolithography (SL), known as a SFF technique, is utilized to build the resin mould, based on which poly-dimethylsilicone (PDMS) mould is produced by microreplication. The chitosan/gelatin hybrid solution is then cast onto the PDMS mould for pre-freeze and the monolayer porous structures with organized internal morphology are produced upon lyophilization. The 3D scaffold can be constructed via stacking these monolayer structures. The properties of porous structure, such as porosity, pore size and micromorphology as well as wall thickness, were investigated. Scanning electron microscopy (SEM) demonstrated that the scaffold possesses multilevel organized internal morphologies including vascular systems (portal vein, artery and hepatic vein) and parenchymal component (hepatocyte chamber). These organized structures enable orderly arrangement of hepatocyte and hepatic nonparenchymal cells and co-culture in the same 3D scaffold to guide liver regeneration in a controlled manner. Cell culture experiment in vitro showed that hepatocytes perform better in the well-defined chitosan/gelatin scaffold than in porous scaffold. This approach makes it flexible to investigate the relationship between internal scaffold microstructure and hepatocyte behavior in vitro. It also provides a new way to fabricate complex 3D scaffold using various natural biomaterials for vital organ engineering. [Copyright &y& Elsevier]

Generally, many beamforming methods are derived under the assumption of white noise. In practice, the actual underwater ambient noise is complex. As a result, the noise removal capacity of the beamforming method may be deteriorated considerably. Furthermore, in underwater environment with extremely low signal-to-noise ratio (SNR), the performances of the beamforming method may be deteriorated. To tackle these problems, a noise removal method for uniform circular array (UCA) is proposed to remove the received noise and improve the SNR in complex noise environments with low SNR. First, the symmetrical noise sources are defined and the spatial correlation of the symmetrical noise sources is calculated. Then, based on the preceding results, the noise covariance matrix is decomposed into symmetrical and asymmetrical components. Analysis indicates that the symmetrical component only affect the real part of the noise covariance matrix. Consequently, the delay-and-sum (DAS) beamforming is performed by using the imaginary part of the covariance matrix to remove the symmetrical component. However, the noise removal method causes two problems. First, the proposed method produces a false target. Second, the proposed method would seriously suppress the signal when it is located in some directions. To solve the first problem, two methods to reconstruct the signal covariance matrix are presented: based on the estimation of signal variance and based on the constrained optimization algorithm. To solve the second problem, we can design the array configuration and select the suitable working frequency. Theoretical analysis and experimental results are included to demonstrate that the proposed methods are particularly effective in complex noise environments with low SNR. The proposed method can be extended to any array. [ABSTRACT FROM AUTHOR]

A maskless electrohydrodynamic direct-writing lithographic strategy was presented to flexibly fabricate user-specific micropatterns on silicon substrates. By optimizing the operating parameters, parallel lines as well as lattices with line width of about 2 μm could be stably deposited. The printed micropatterns were found to function as sacrificial template to transfer microstructures into silicon substrates and the etching processes had little effect on the predefined size. It is envisioned that this simple approach provides an alternative to the existing microfabrication techniques, which might enable the wide accessibility of microscale technologies to advance various research fields such as microfluidics, biomedical chips, and microscale tissue engineering. [ABSTRACT FROM AUTHOR]

The article presents a study which describes the use of rapid prototyping (RP) and computer-aided design for the preoperative planning and fabrication of custom-made implants. It states that an RP machine fabricated the geometry of a custom made implant. It concludes that the stereolithography model proved to be an accurate tool for preoperative and surgical stimulation.

During the past few years, the combination of medical imaging and rapid manufacturing technique has proven to be a very important development. On the other hand, the conventional method has some drawbacks. For example, it takes longer time to complete an operation and it also presents some difficulty in matching the repaired contours. With advanced software and hardware, an image of an undamaged bone similar to that of the patient can be made from computerised tomography (CT); and a physical object constructed by the mirror-processed image data can be quickly fabricated with a high degree of fitting with the patient’s bone.This paper presents a methodology for the design and fabrication of an individual titanium tray for the repair of mandible defects. Methods for the tray modeling using CAD system are presented: A 3D model of the bony defect is generated after the acquisition of helical CT data. An individual tray is designed using freeform surfaces geometries and fabricated by rapid prototyping (RP) technology. The results of tray filling with bone-grafting materials are then presented. Result: the tray is inserted into the patient mandible segment. The symmetry and reconstruction quality contour of the repaired mandible was satisfactory. Thus, the patient is able to eat normally. The bone-grafting material harvested from the anterior ilium was low. The clinical experience showed that rapid prototyping and reverse engineering software are effective methods of fabricating custom trays for mandibular reconstruction after bone loss due to a tumor. [Copyright &y& Elsevier]

It is challenging for the existing three-dimensional (3D) printing techniques to fabricate high-resolution 3D microstructures with low costs and high efficiency. In this work we present a solvent-based electrohydrodynamic 3D printing technique that allows fabrication of microscale structures like single walls, crossed walls, lattice and concentric circles. Process parameters were optimized to deposit tiny 3D patterns with a wall width smaller than 10 μm and a high aspect ratio of about 60. Tight bonding among neighbour layers could be achieved with a smooth lateral surface. In comparison with the existing microscale 3D printing techniques, the presented method is low-cost, highly efficient and applicable to multiple polymers. It is envisioned that this simple microscale 3D printing strategy might provide an alternative and innovative way for application in MEMS, biosensor and flexible electronics. [ABSTRACT FROM AUTHOR]