Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine最新文献

As the field of prosthetics moves away from traditional subtractive manufacturing methods toward more sustainable, customizable approaches like 3D printing, this study examines how varying clearance values in cycloidal drives impact their vibrational behavior. Cycloidal drives known for their high torque density and low backlash, are gaining traction as key reduction components in robotic prostheses, where minimizing vibration is essential for ensuring smooth gait transitions, reducing user fatigue, and improving long-term prosthetic wear comfort. This study investigates the vibrational performance of 3D-printed cycloidal drives by evaluating different clearances to optimize vibrational performance in robotic prostheses applications, specifically in robotic knee joints. In this research, three clearance values (0.2, 0.3, and 0.5 mm) were tested on a benchtop using 3D-printed cycloidal drives. With the retrieved raw gyroscope data, a combination of ANOVA and time-frequency analyses was employed to evaluate their vibrational performance across different speeds and load conditions. The study revealed that the 0.2 mm clearance, while effective at higher speeds, exhibited greater variance, and concentrated vibrational energy at lower speeds, which could cause localized stress and wear. The 0.3 mm clearance emerged as the most balanced, with minimal variance, evenly distributed vibrational energy, and greater durability, making it ideal for high-precision applications like prosthetic joints. In contrast, the 0.5 mm clearance exhibited erratic behavior, with excessive vibration and mechanical noise, making it the least favorable option.

This study aims to develop an effective system for transporting civilians injured in natural disasters, accidents, or terrorist attacks to hospitals quickly. The system's design, prototyping, and performance tests focussed on ensuring that a patient could be seated in a modular chair, easily lifted and secured to the back of a motorcycle, while maintaining balance during loading, transport, and unloading. A key requirement was enabling a single operator to carry out the operation safely, with the patient seated backward. The design includes a detachable seat, which is similar to a wheelchair, connected to the motorcycle. A prototype was built and tested on a cargo scooter with a 125 -cc engine. After analysis, simulations, and successful road tests with a full-size passenger test dummy, the data showed that the system's performance matched theoretical expectations, particularly in speed and cornering. The prototype demonstrated excellent road performance. In addition, the measured loading and unloading time of the patient seat was below 2 min, and the prototype completed the 50 m, 14% slope (Track2) without rearing or instability. Manoeuvrability results were compared against the baseline scooter (driver only), showing similar speeds and slightly lower lateral accelerations due to cautious driving.

Tracheal diseases such as tracheal stenosis and tracheomalacia often have a significant impact on patients' respiratory function. Traditional tracheal stents face issues such as displacement, granulation tissue hyperplasia, and axial foreshortening during clinical use, which limit their long-term efficacy. The mechanical behavior of auxetic tracheal stents was studied, focusing on the impact of design parameters on stent performance. Finite element analysis was used to assess the effects of different unit cell strut geometries (including connecting strut shape and unit cell core design) on the stent's stress-strain behavior, expansion performance, and anti-migration properties. The results show that the curved design stent exhibits a nonlinear stress-strain relationship similar to that of the trachea. The multi-circular core design demonstrated the best overall performance, with a radial recoil rate of 6.6% and a maximum anti-migration force of 641 N, representing a 51% improvement over the straight-bar stent. The multi-circular design significantly reduces the risk of granulation tissue formation through uniform stress distribution (maximum principal stress of 136 MPa) and low tracheal wall stress (0.24 MPa), making it a promising candidate for long-term implantation. This study provides theoretical support for the optimization of tracheal stent designs and lays the foundation for the long-term implantation of auxetic tracheal stents in the future.

The limitations faced by individuals with transtibial leg amputations highlight the need for rehabilitation devices with enhanced performance. Energy Storing and Returning (ESAR) prosthetic devices have emerged as a promising solution, utilizing innovative designs and materials to enhance the range of motion for these individuals. This study presents a workflow for evaluating J-shaped ESAR prosthetic blades under gait-specific conditions, investigating their behavior during various states of movement corresponding to the natural human gait cycle. A model based on the general structure of J-shaped below-knee prosthetic blades have been designed and simulated using different materials. The performance of the prosthesis has been evaluated during standing, walking, running, and hurdling. Finite Element analyses have been conducted using Abaqus CAE. OpenSim has been employed to simulate the natural gait cycle during walking and running, and the results have been utilized as loading input and boundary conditions for Abaqus simulations. Abaqus built-in Auricchio-Taylor Constitutive model has been utilized to simulate the super-elastic behavior of NiTinol. In the results section, various parameters such as von Mises stress, elastic strain, total deformation, strain energy, and mass have been compared. NiTinol composite and carbon fiber composite exhibited the best performance, with the carbon fiber composite being significantly lighter, weighing 68% less than NiTinol composite. The comprehensive method and procedure proposed in this study can be employed for further research in the field of prosthetic feet, as well as generalized for a wide range of rehabilitation devices.

The growth of assistive technology has increased the use of smart wearable orthoses. This is driven by improved sensors, actuators, cheaper integrated circuits, better data connectivity for data acquisition, and advanced manufacturing techniques. These smart devices correct, support, and monitor physical deformities and movements. This study reviews recent literature on smart wearable orthotic devices' design, application, and fabrication. The focus is on biomedical uses and advanced manufacturing methods. A total of 79 peer-reviewed articles were identified. After screening based on titles, abstracts, and full texts, 52 articles were selected. This article provides a state-of-the-art review and analysis of smart wearable orthoses with sensor systems and manufacturing techniques such as computer-aided design, computer-aided manufacturing, additive manufacturing, and the Internet of Things used in medical rehabilitation and health monitoring. The findings highlight the role of smart orthoses in physical rehabilitation and deformity management. They offer valuable support in managing musculoskeletal conditions. This review provides researchers with insights into current trends and technologies in the field. It also identifies opportunities for innovation in orthotic design. Based on the review, researchers in the field of assistive technology can understand the avenue of development of newer and more innovative orthoses for different deformities and identify relevant technology to their work. One such promising domain is smart orthotics intervention in clubfoot treatment in low-resource environments where access to conventional long-term care is restricted.

Cardiovascular diseases pose a significant global health challenge, necessitating advancements in precision-driven interventional techniques. Robotic-assisted cardiac catheterization integrates high-precision mechanical systems, including roller-based, gear-driven, and belt-pulley mechanisms, for controlled catheter manipulation. Spring-loaded force dynamics characterize catheter deformation, aiding in torque estimation across various material compositions. This study presents a hybrid control algorithm that enhances motion accuracy by optimizing overshoot percentages and settling times, outperforming conventional controllers while maintaining stable proportional-integral-derivative ($k_p$, $k_i$, $k_d$) parameters. The robotic system achieves translational catheter motion at approximately 0.060 rad/s, ensuring a precise displacement of nearly 1 mm/s. Rotational movement at 0.98 rad/s enables an angular shift of 0.9° per pulse, ensuring smooth, and predictable navigation. Experimental validation of the Feed-Forward PID (FFPID) controller confirmed high accuracy, stability, and responsiveness. Displacement tracking showed minimal error (RMSE < 0.017 mm, $R^2$ = 0.999), while rotational control maintained angular precision (RMSE < ${0.11}^{°}$, overshoot < 1%). These results validate the FFPID controller's effectiveness for real-time catheter control in robot-assisted cardiac procedures. Real-time sensor feedback enables dynamic trajectory adjustments, fine-tuning motion control for improved procedural accuracy. A dedicated surgeon-centric control panel allows seamless bidirectional catheter manipulation, ensuring intuitive handling for intricate interventions. The integration of advanced hardware and an adaptive hybrid control strategy minimizes tracking errors and optimizes efficiency. This research highlights the transformative impact of hybrid control methodologies in robotic-assisted interventions, paving the way for more intelligent and autonomous cardiovascular surgical systems.

The aim of this study was to preliminarily use machine learning and finite element methods to predict the multiple-needle ablation size of spinal and paraspinal tumors and to use genetic algorithms to solve for the optimal ablation parameters under specific ablation size conditions. A two-dimensional two-needle spinal tumor ablation finite element model was created. Its ablation size was analyzed under different approach angles, electrode lengths, electrode diameter, ablation temperatures, and time conditions. Three neural-network models (back propagation (BP), radial basis function (RBF) and convolutional neural-networks (CNN)) were trained separately using the results of the finite element analysis as a dataset (eight inputs and five outputs) and the performance of these neural-network models was compared. The results showed that compared with the RBF and CNN, the BP neural-network has the smallest root mean square error (RMSE) value on the test set (compared with RBF and CNN, the BP neural-network decreased by 55.06% and 56.71%, respectively). This indicated that the BP neural-network has better generalization ability and prediction accuracy compared with RBF and CNN and was more suitable to be used as a machine learning model in this study. Appropriate adjustment of the angle between the needles could effectively control the morphology of the ablation region and avoid damage to the surrounding healthy tissues. Using machine learning and genetic algorithms to predict the size of multi-needle ablation region and optimal ablation parameters could significantly improve research efficiency.

Stem cells possess the unique abilities to self-renew and differentiate into various cell types, making them invaluable in tissue engineering and regenerative medicine. This study explores the behavior of human bone marrow-derived mesenchymal stem cells (hMSCs) on poly(dimethylsiloxane) (PDMS) substrates with hierarchical wrinkle patterns. These bio-inspired patterns were created using the surface instability of gold-coated elastomer bilayers. The results indicate that the hierarchical wrinkles not only promote cell alignment but also up-regulate tenogenic differentiation markers without chemical induction. The cells exhibited increased expression of tenocyte markers (Mkx, and Col1) and decreased expression of osteoblast (Alp, and Opn) and chondrocyte (Sox9) markers. This bio-inspired substrate design, mimicking natural extracellular matrix structures, provides a promising approach for developing functional tissue constructs and advancing stem cell-based regenerative therapies. The study underscores the importance of substrate topography in directing stem cell fate, highlighting its potential in mechanobiological applications and tissue engineering.

Low back pain is estimated to affect more than 70% of the population. Recently, interspinous posterior devices are gaining attention as a less invasive alternative to the traditional pedicle screw systems. However, since most of these devices are not suitable for the L5-S1 segment, the goals for this study are to design a tailored fixation system for the L5-S1 level and to study its effects on the degenerated spine. To that end, a finite element model of the L4-S1 spinal segment was developed, considering three different clinical stages (healthy, mildly degenerated and moderately degenerated). The instrumented spine was then simulated in short-term and long-term post-surgery stages, combined with the degenerated conditions. This system was able to effectively reduce the movement of the implanted segment by up to 96% in flexion and extension, 80% in lateral bending and 83% in axial rotation. In what concerns to the maximum principal stress in the disc region, the implanted model has shown a reduction of 80% in flexion, 76% in extension and 78% in lateral bending. These are promising outputs in terms of reducing the movement and the stress levels of the instrumented spine in all directions of motion, particularly flexion and extension, even if the device would require further experimental, computational and clinical studies. Although the mobility of the L4-L5 segment was not altered in the simulations, minor changes in the stress distribution were found in this segment, suggesting a reduced probability of adjacent disc disease with this system.

This study provides valuable guidance for simplifying fabrication procedures and enhancing the structural integrity and safety of carbon fiber (CF) laminate transfemoral (TF) prosthetic sockets. While the high specific strength of CF laminate sockets offers advantages over conventional plastics, essential production data-their orientation-dependent strength and optimal cure conditions-are lacking, often requiring complex, costly cure cycles. This study investigated (i) the influence of fiber orientation on TF prosthetic CF socket strength via finite element analysis (FEA) during standing, and (ii) optimal single-step Vacuum-Bag-Only (VBO) cure conditions for prepreg in a low-cost conventional oven. Three distinct CF laminates ((45/-45/45/-45), (0/90/0/90), (0/45/-45/90)) were implemented in TF socket finite element (FE) models. Tensile and flexural tests validated FE results and assessed laminate failure modes. Differential Scanning Calorimetry (DSC) investigated cure temperatures, while surface voids were inspected to identify optimal single-step cure conditions. A 1-h isothermal cure at 90°C facilitated resin flow and yielded minimal surface voids. FEA revealed ply orientations insignificantly influenced residual limb pressure. Most plies in the (45/-45/45/-45) CF laminate favorably aligned with oblique deformation for TF socket stabilization during standing. Experimentally, it exhibited the lowest stiffness (10.86 GPa) and strength (161.49 MPa). Nevertheless, its strength is superior to other socket materials and enhances safety through clear pre-fracture signs from ductile failure. Maximum pressure of up to 32.2 kPa at the medial-distal site during standing was insufficient to cause discomfort. These findings provide guidelines for high-quality TF sockets using prepreg by simplifying the fabrication process.