Search Results (70)

Background/Objectives: Limited residual bone height in the atrophic posterior maxilla complicates implant placement. Transcrestal sinus elevation can be used to correct bone shrinkage after sinus pneumatization or crestal bone loss. This study evaluated a minimally invasive, one-stage transcrestal sinus lift using a double-layer crosslinked collagen scaffold (MCCS) with autogenous bone from the implant osteotomy site in patients with RBH ≤ 6 mm. Methods: In this prospective series, 11 patients (48–64 years, mean RBH 4.75 mm, SD 0.95 mm) underwent one-stage transcrestal sinus floor elevation with simultaneous implants. After osteotomy, autogenous bone chips collected during drilling were compacted into the site, and two layers of MCCS were placed under the elevated Schneiderian membrane. Buccal and palatal bone heights were measured on CBCT before and after surgery to assess vertical bone gain (ΔRBH). Results: All implants achieved stable osseointegration. Mean ΔRBH was approximately 3.1 ± 0.9 mm (combined buccal–palatal). No postoperative complications occurred. Two small Schneiderian membrane perforations were sealed intraoperatively by MCCS placement, with uneventful healing. Follow-up imaging showed maintenance of the augmented bone around the implants. Conclusions: This double-layer MCCS plus autogenous bone approach is a safe, effective, and minimally invasive transcrestal sinus lift for atrophic maxillae. It yielded crestal bone gains even with minimal initial RBH, leveraging the palatal sinus wall’s osteogenic potential and the implant’s tent-pole effect. The MCCS scaffold maintained space for bone formation and enabled immediate sealing of any membrane perforations. This one-stage protocol is viable for implant placement in low-RBH sites. Full article

Nowadays, attempts to commercially apply non-pneumatic tires (NPTs) in a wide range of vehicles can be observed. These types of wheels use a specific structure and material selection to mimic the function of compressed air in pneumatic tires (PTs). This paper reviews the mechanical properties and vehicle applications of non-pneumatic tires. This review will provide information about the influence of the shape of the radial, longitudinal, and lateral characteristics, as well as the possibility of selecting contact pressure values at the wheel design stage and the influence of the type of elastic structure on the concentration of pressures in the contact length. The radial characteristics of non-pneumatic tires depend on the type of elastic structure. The spoked elastic structure will be characterized by greater displacements compared to the cellular structure, which will reduce radial stiffness. The radial stiffness of non-pneumatic tires is increased by increasing the number of elastic structure elements and their thickness and decreasing their length. The longitudinal stiffness of non-pneumatic tires increases with the number of elements forming the elastic structure and with the elastic structure’s lack of susceptibility to circumferential deformation. Spoked non-pneumatic tires will have lower longitudinal stiffness compared to cellular non-pneumatic tires. The elastic structure is characterized by a low susceptibility to lateral deformation, which contributes to the high lateral stiffness of the non-pneumatic tire. Non-pneumatic tires have a limited ability to shape the contact patch parameters, which mainly depend on the vertical load and the shape of the tread area. The type of band used will influence the formation of contact pressures. An isotropic elastomer used in a shear band will cause pressure concentration at the ends of the contact length. A more uniform pressure distribution is achieved by using a laminated elastomer. Full article

Three-dimensional bioprinting holds great promise for tissue engineering, but struggles with fabricating complex curved geometries such as vascular networks. Though precise, traditional Cartesian bioprinters are constrained by linear layer-by-layer deposition along fixed axes, resulting in limitations such as the stair-step effect. Multi-axis robotic bioprinting addresses these challenges by allowing dynamic nozzle orientation and motion along curvilinear paths, enabling conformal printing on anatomically relevant surfaces. Although robotic arms offer lower mechanical precision than CNC stages, accuracy can be enhanced through methods such as vision-based toolpath correction. This study presents a modular multi-axis robotic embedded bioprinting platform that integrates a six-degrees-of-freedom robotic arm, a pneumatic extrusion system, and a viscoplastic support bath. A streamlined workflow combines CAD modeling, CAM slicing, robotic simulation, and automated execution for efficient fabrication. Two case studies validate the system’s ability to print freeform surfaces and vascular-inspired tubular constructs with high fidelity. The results highlight the platform’s versatility and potential for complex tissue fabrication and future in situ bioprinting applications. Full article

Soft manipulators have garnered significant research attention in recent years due to their flexibility and adaptability. However, the inherent flexibility of these manipulators imposes limitations on their load-bearing capacity and stability. To address this, this study compares various variable stiffness technologies and proposes a novel design concept: leveraging the phase-change characteristics of low-melting-point alloys (LMPAs) with distinct melting points to fulfill the variable stiffness requirements of soft manipulators. The pneumatic structure of the manipulator is fabricated via 3D-printed molds and silicone casting. The manipulator integrates a pneumatic working chamber, variable stiffness chambers, heating devices, sensors, and a central channel, achieving multi-stage variable stiffness through controlled heating of the LMPAs. A steady-state temperature field distribution model is established based on the integral form of Fourier’s law, complemented by finite element analysis (FEA). Subsequently, the operational temperatures at which the variable stiffness mechanism activates, and the bending performance are experimentally validated. Finally, stiffness characterization and kinematic performance experiments are conducted to evaluate the manipulator’s variable stiffness capabilities and flexibility. This design enables the manipulator to switch among low, medium, and high stiffness levels, balancing flexibility and stability, and provides a new paradigm for the design of soft manipulators. Full article

In recent years, pneumatic stages have attracted attention as stages for semiconductor manufacturing equipment due to their low cost and minimal maintenance requirements. However, pneumatic stages include nonlinear elements such as friction and air compressibility, making precise control challenging. To address this issue, this paper aims to achieve high-precision positioning by applying a nonlinear position control method to pneumatic stages. To achieve this, we propose a control method that combines filtered right coprime factorization and Prescribed Performance Control–Sliding Mode Control (PPC-SMC). Filtered right coprime factorization not only stabilizes and simplifies the plant but also reduces noise. Furthermore, PPC-SMC enables safer and faster control by constraining the system state within a switching surface that imposes limits on the error range. Through experiments on the actual system, it was confirmed that the proposed method achieves dramatically higher precision and faster tracking compared to conventional methods. Full article

Soft-growing robots based on the eversion principle are renowned for their ability to rapidly extend along their longitudinal axis, allowing them to access remote, confined, or otherwise inaccessible spaces. Their inherently compliant structure enables safe interaction with delicate environments, while their simple actuation mechanisms support lightweight and low-cost designs. Despite these benefits, implementing effective navigation mechanisms remains a significant challenge. Previous research has explored the use of pneumatic artificial muscles mounted externally on the robot’s body, which, when contracting, induce directional bending. However, this method only offers limited bending performance. To enhance maneuverability, pneumatic artificial muscles embedded in between the walls of double-walled eversion robots have also been considered and shown to offer superior bending performance and force output as compared to externally attached muscle. However, their adoption has been hindered by the complexity of the current manufacturing techniques, which require individually sealing the artificial muscles. To overcome this multi-stage fabrication approach in which muscles are embedded one by one, we propose a novel single-step method. The key to our approach is the use of non-heat-sealable inserts to form air channels during the sealing process. This significantly simplifies the process, reducing production time and effort and improving scalability for manufacturing, potentially enabling mass production. We evaluate the fabrication speed and bending performance of robots produced in this manner and benchmark them against those described in the literature. The results demonstrate that our technique offers high bending performance and significantly improves the manufacturing efficiency. Full article

This study introduces a machine vision system (MVS) developed for the inspection and removal of defective gears to enhance the efficiency of mass production processes. The system employs a rotary table that transports gears through the inspection stage at a controlled speed. Various defects, including missing teeth, surface irregularities, and dimensional deviations, are reliably identified through this method. Faulty gears are automatically separated from the production line using a pneumatic actuator. Experimental evaluations confirm the system’s high accuracy and consistency, with a defect detection standard deviation of less than 1%. This level of deviation corresponds to a defect detection accuracy exceeding 98%, with both precision and recall consistently surpassing 96%. By reducing manual intervention and accelerating quality control procedures, the proposed system contributes to improved production efficiency and product quality, offering a practical and effective solution for manufacturing environments. Full article

Variable stiffness actuators (VSAs) have attracted considerable attention in wearable robotics and soft exoskeletons due to their ability to adapt to various load conditions. This study presents a modular design for VSAs that incorporates a chain mail structure with various link topologies, allowing for a reconfiguration of stiffness. The proposed VSA consists of three main parts: the vacuum chamber, the VSA actuator, and the chain mail structure. The VSA fabrication process was carried out in five stages: (1) mold fabrication by 3D FDM printing, incorporating a film of oil to facilitate easy demolding; (2) mold preparation using silicone, with a precise ratio of 1:1 weight-based mixture to optimize material utilization; (3) silicone pouring into molds while applying vibration to eliminate air bubbles; (4) curing for four hours to achieve optimal mechanical properties; and (5) careful demolding to prevent damage. Experimental tests were conducted to characterize the stiffness of actuators with different chain mail fabric configurations, using an experimental setup designed to securely fix the actuator and accurately measure the pneumatic pressure and the angle of deformation after applying weights at its end. The European 6-in-1 and rounded square configurations were shown to be the most effective, increasing stiffness up to 382% compared to the chain mail-free configuration, highlighting the positive impact of these structural designs. Full article

Implant–prosthetic rehabilitation of the posterior edentulous maxilla is challenging due to inadequate bone volume resulting from alveolar ridge resorption and maxillary sinus pneumatization. This study explores the use of hyaluronic acid (HA) as a biomaterial in maxillary sinus elevation, particularly in combination with a fluid dynamic approach, as an alternative to traditional lateral approaches and granular biomaterials. Methods: A prospective study was conducted on 58 patients with posterior maxillary edentulism. Preoperative CBCT scans assessed residual bone height and sinus width. A minimally invasive surgical protocol utilizing a device for fluid-dynamic membrane elevation and injection of 2% cross-linked hyaluronic acid was employed, followed by simultaneous implant placement. Postoperative follow-up included a CBCT scan at 12 months to evaluate new bone height, measured mesially and distally. Implant stability was assessed using resonance frequency analysis at second-stage surgery. Results: A significant increase in bone height was observed at 12 months post-surgery, with an average bone gain of 7.5 mm. All 58 implants achieved primary stability, and no implant failures or signs of peri-implantitis were noted during the follow-up period. Higher bone gain was observed in wider sinuses. Conclusions: The fluid-dynamic transcrestal sinus floor elevation technique combined with hyaluronic acid appears to be a minimally invasive and effective method for achieving significant bone regeneration in the posterior maxilla, facilitating implant–prosthetic rehabilitation with potentially low risks and morbidity. Further large-scale studies are warranted to validate these findings across diverse clinical scenarios. Full article

Stroke-related hand dysfunction significantly limits the ability to perform daily activities. Pneumatic soft gloves can provide rehabilitation training and support for individuals with impaired hand function, enhancing their independence. This paper presents a novel pneumatic soft robotic system for hand rehabilitation featuring bidirectional bending actuators. The system comprises a pneumatic soft glove and a pneumatic control platform, enabling various rehabilitation gestures and assisting with finger grasping. The main bending module of the pneumatic soft actuator features a three-stage cavity structure, allowing for a wider range of finger rehabilitation training gestures and greater bending angles. The reverse-bending module uses a trapezoidal cavity design to enhance the reverse-bending capability, effectively facilitating finger extension motion. The pneumatic control platform is simple to set up, but effectively controls the actuators of the soft glove, which enables both main and reverse bending. This allows individuals with hand impairments to perform various gestures and grasp different objects. Experiments demonstrate that the pneumatic soft glove has a measurable load capacity. Additionally, the pneumatic soft glove system is capable of executing single-finger movements, a variety of rehabilitation gestures, and the ability to grasp different objects. This functionality is highly beneficial for the rehabilitation of individuals with hand impairments. Full article

The authors would like to make a meaningful contribution to product development strategies by introducing an original holistic design methodology for pressure-containing equipment. A case study is presented, focusing on the design enhancement of a pneumatic cylinder for valve actuators. The purpose of the discussed methodology is supplying designers with a full picture of the product, usually not directly available, thanks to the extensive use of advanced Finite Element Analysis (FEA) to increase confidence in the safety and reliability of the design at the virtual prototype stage while providing useful insights that can be used during product life in occasions such as root cause analyses. The new design approach is applied to the cylinder by analyzing it in special conditions like during a pressure burst test using an FEA. A comparison with the experimental results confirms that the proposed methodology can potentially contribute to introducing renewed, safe, reliable, and lighter components, reducing the cost and time of development. Full article

As the world’s population continues to rise while the agricultural workforce declines, farmers are increasingly challenged to meet the growing food demand. Strawberries grown in the U.S. are especially threatened by such stipulations, as the cost of labor for such a delicate crop remains the bulk of the total production costs. Autonomous systems within the agricultural sector have enormous potential to catalyze the labor and land expansions required to meet the demands of feeding an increasing population, as well as heavily reducing the amount of food waste experienced in open fields. Our team is working to enhance robotic solutions for strawberry production, aiming to improve field processes and better replicate the efficiency of human workers. We propose a modular configuration that includes a Delta X parallel robot and a pneumatically powered end effector designed for precise strawberry harvesting. Our primary focus is on optimizing the design of the end effector and validating its high-speed actuation capabilities. The prototype of the presented end effector achieved high success rates of 94.74% in simulated environments and 100% in strawberry fields at Farias Farms, even when tasked to harvest in the densely covered conditions of the late growing season. Using an off-the-shelf robotic configuration, the system’s workspace has been validated as adequate for harvesting in a typical two-plant-per-row strawberry field, with the hardware itself being evaluated to harvest each strawberry in 2.8–3.8 s. This capability sets the stage for future enhancements, including the integration of the machine vision processes such that the system will identify and pick each strawberry within 5 s. Full article

The results of the first stage of work aimed at improving a hybrid drive system in which the combustion engine is supported by a pneumatic–hydraulic motor are presented. The purpose of the described work was to show that a heat exchanger with a design adapted to the operating conditions of a pneumatic–hydraulic motor would allow sufficient air heating at the expense of waste heat from the combustion engine, thus increasing the efficiency of the drive system. It was assumed that the key component of the heat exchanger would be copper foam in order to increase the heat exchange surface. A prototype modular heat exchanger was designed and tested. An open-cell copper foam with a porosity of 0.9 and a pore density of 40PPI was placed in the heat exchanger. Experimental and numerical air heating studies were carried out under various heat exchanger operating conditions. The tests were conducted at initial air temperatures of −123 °C, −71 °C, and 22 °C and air pressures of 2.5 × 10⁶ and 7.0 × 10⁶ Pa. The air mass flux was in the range of 3.6–1644 kg/(m²s). It was found that the tested heat exchanger allows a reduction in air consumption in the drive system of 11% to 58% and increases the efficiency of the air expansion system by 16% to 30%. The maximum efficiency of the heat exchanger is 96%. The results of the work carried out will help to improve the pneumatic–hydraulic drive systems of work machines and vehicles. Full article

Background/Objectives: Delayed gastric conduit emptying (DGCE) occurs in 15–39% of patients who undergo esophagectomy. Intra-Pyloric Injection of Botulinum Toxin (IPBT), Pneumatic Balloon Dilation (PBD), and the same session combination (BTPD) represent the main endoscopic procedures, but comparative data are currently unavailable. Methods: We retrospectively analyzed prospectively collected data on all consecutive patients with DGCE treated endoscopically with IPBT, PBD, or BTPD. ISDE Diagnostic Criteria were used for DGCE diagnosis and classification. A Gastric Outlet Obstruction Score was used for clinical staging. All patients undergoing IPBT received 100 UI of toxin, while those undergoing PBD were dilated up to 20 mm. Clinical success (CS) was defined as the resolution of symptoms/resumption of feeding at discharge or expanding dietary intake at any rate. Recurrence was defined as symptom relapse after more than 15 days of well-being requiring endoscopic/surgical intervention. Results: A total of 64 patients (81.2% male, 90.6% Ivor-Lewis esophagectomy, 77.4% adenocarcinoma) with a median age of 62 years (IQR 55–70) were enrolled: 18 (28.1%) in the IPBT group, 24 (37.5%) in the PBD group, and 22 (34.4%) in the BTPD group. No statistically significant differences were found in the baseline characteristics, surgical techniques, and median follow-up among the three groups. BTPD showed a higher CS rate (100%) compared to the PD and BTPD groups (p = 0.02), and a Kaplan–Meier analysis with a log–rank test revealed that the BTPD group was associated both with a significatively shorter mean time to refeed of 1.16 days (95% CI 0.8–1.5; p = 0.001) and a shorter median time to discharge of one day (95% CI 1–3; p = 0.0001). Conclusions: Endoscopic management of DGCE remains challenging. Waiting for further strong evidence, BTPD can offer patients a higher clinical efficacy rate and a shorter time to refeed and be discharged. Full article

Taking a four-stage transonic compressor as the research object, the Lagrange particle tracking method was used to simulate the multiphase flow by considering the particle fragmentation, collision and evaporation models, and the influence of different inlet conditions (raindrop diameter, velocity, temperature and flow rate) on the compressor’s performance and stable working range was studied. The results show that inlet rain absorption can weaken the clearance leakage vortex make the shock wave move downstream, thus increasing the inlet flow rate, resulting in a decrease in stability margin and the highest efficiency point moving in the direction of flow increase. With the decrease in raindrop diameter, the pressure ratio and wet compression efficiency increase, and the stability margin decreases. With the increase in inlet raindrop velocity, the degree of pneumatic breakage increases and the raindrop diameter becomes smaller, which leads to the decrease in pressure ratio and efficiency. The influence of the mass flow rate of imported raindrops on the stable working range is significant. When the mass flow rate of imported raindrops accounts for 5% of the design flow, the stable working range can be reduced by more than half. Rain absorption increases the reaction force of the compressor and increases the load of the rotor blade. Full article