Search Results (815)

Cell micromanipulation is an important technique in the field of biomedical engineering. Microgrippers play a crucial role in connecting macroscopic and microscopic objects in micromanipulation systems. However, since the operated biological cells are deformable, vulnerable, and typically distributed in sizes ranging from micrometers to millimeters, it poses a huge challenge to microgripper performance. To solve this problem, this paper develops a dual-driven piezoelectric microgripper with a high displacement amplification ratio, large stroke, and parallel gripping. By adopting modular configuration, three kinds of flexure-based mechanisms, including the lever mechanism, Scott–Russell mechanism, and parallelogram mechanism are connected in series to realize three-stage amplification, which effectively makes up for the shortage of small output displacement of the piezoelectric actuator. At the same time, the use of the parallelogram mechanism also isolates the parasitic rotation movement, and realizes the parallel movement of the gripping jaws. In addition, the kinematics, statics, and dynamics models of the microgripper are established by using the pseudo-rigid body and Lagrange methods, and the key geometric parameters are also optimized. Finite element simulation and experimental tests verify the effectiveness of the developed microgripper. The results show that the developed microgripper allows an amplification ratio of 46.4, a clamping stroke of 2180 $\mathsf{\mu }$m, and a natural frequency of 203.1 Hz. Based on the developed microgripper, the nondestructive micromanipulation of zebrafish embryos is successfully realized. Full article

Hand paralysis, caused by conditions such as spinal cord injuries, strokes, and arthritis, significantly hinders daily activities. Wearable exo-gloves and telerehabilitation offer effective hand training solutions to aid the recovery process. This study presents the development of lightweight wearable exo-gloves designed for finger telerehabilitation. The prototype uses NiTi shape memory alloy (SMA) actuators to control five fingers. Specialized end effectors target the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints, mimicking human finger tendon actions. A variable structure controller, managed through a web-based Human–Machine Interface (HMI), allows remote adjustments. Thermal behavior, dynamics, and overall performance were modeled in MATLAB Simulink, with experimental validation confirming the model’s efficacy. The phase transformation characteristics of NiTi shape memory wire were studied using the Souza–Auricchio model within COMSOL Multiphysics 6.2 software. Comparing the simulation to trial data showed an average error of 2.76°. The range of motion for the MCP, PIP, and DIP joints was 21°, 65°, and 60.3°, respectively. Additionally, a minimum torque of 0.2 Nm at each finger joint was observed, which is sufficient to overcome resistance and meet the torque requirements. Results demonstrate that integrating SMA actuators with telerehabilitation addresses the need for compact and efficient wearable devices, potentially improving patient outcomes through remote therapy. Full article

This paper presents a novel exoskeleton robot that can be used at home to rehabilitate the index fingers of stroke-affected patients. This exoskeleton is designed as a one-degree-of-freedom four-bar mechanism able to guide the human index finger to perform a finger curl exercise motion. The proposed device is the only lateral, stand-alone mechanism built to date that can carry the weight of the human hand, thus making the user free from wearing it. The design starts by tracing the trajectory of the index finger using ‘Angulus’ software. ‘SALAR Mechanism Synthesizer’ software is used for dimensional synthesis of the four-bar mechanism. Using additive manufacturing technology, a prototype of the proposed device is developed. Static force analysis is performed to select the most appropriate actuator for producing the required torque to manipulate the fingers effectively. The kinematics of the index finger while performing a finger curl exercise is obtained. The proposed linkage mechanism can drive the index fingers of both hands. Simulation and experimental results proved the feasibility and effectiveness of the proposed design to be used for index finger rehabilitation for a wide range of users and applications by making simple minor alterations in the design. Also, a scheme for when the device can be used for rehabilitating the middle finger together with the index finger when performing flexion and extension motions is discussed. Full article

The internal combustion engines of long-endurance UAVs are optimized for cruises, so they are prone to overheating during climbs, when power requests increase. To counteract the phenomenon, step-climb maneuvering is typically operated, but the intermittent high-power requests generate repeated heating–cooling cycles, which, over multiple missions, may promote thermal fatigue, performance degradation, and failure. This paper deals with the development of a model-based monitoring of the cylinder head temperature of the two-stroke engine employed in a lightweight fixed-wing long-endurance UAV, which combines a 0D thermal model derived from physical first principles with an extended Kalman filter capable to estimate the head temperature under degraded conditions. The parameters of the dynamic model, referred to as nominal condition, are defined through a particle-swarm optimization, minimizing the mean square temperature error between simulated and experimental flight data (obtaining mean and peak errors lower than 3% and 10%, respectively). The validated model is used in a so-called condition-based extended Kalman filter, which differs from a conventional one for a correction term in section prediction, leveraged as degradation symptom, based on the deviation of the model-state derivative with respect to the actual measurement. The monitoring algorithm, being executable in real-time and capable of identifying incipient degradations of the thermal flow, demonstrates applicability for online diagnostics and predictive maintenance purposes. Full article

This paper presents an experimental analysis of a high-response piezoelectric actuator system for the modular design of hydraulic digital fluid control units. It focuses on determining static and dynamic characteristics, forming the basis for developing a smart Industry 4.0 component that incorporates both actuator and sensor function. The design process examines the main challenges, advantages, disadvantages, and working principles to define parameters that impact the actuator’s behaviour and performance. The new piezoelectric actuator system features three piezoelectric stack actuators in series, enabling simultaneous actuation and sensing by applying and measuring the electrical voltage at each piezo element. The experimental setup and test methodology are explained in detail, revealing that the new design, combined with an appropriate open-loop or closed-loop control method, offers superior actuator stroke control, high stroke resolution, and a high-dynamic step response. This paper proposes a concept of a smart piezo actuator system focused on I4.0 and an actuator administration shell, integrated with 5G and RFID technology, which will allow automatic plug-and-play functionality and efficient interconnection, communication, and data transfer between the hydraulic valve and the piezoelectric actuator system. Full article

(1) Background: Swallowing disorders are common following a stroke. This study aims to evaluate the effects of a home-based daily intervention focused on inspiratory and expiratory muscle training on swallowing outcomes in patients with chronic stroke. (2) Methods: This manuscript presents the protocol of a single-blind randomized clinical trial. Patients with chronic stroke will be randomly assigned to either an experimental or a control group. The experimental group will undergo daily home-based respiratory muscle training in addition to standard speech and language therapy, while the control group will receive only the standard intervention. The main outcome measures will include the aspiration risk, the strength of respiratory muscles, and peak cough flow. (3) Results: It is hypothesized that patients receiving home-based respiratory training in addition to standard therapy will achieve significant improvements in aspiration risk, respiratory muscle strength, and cough efficacy in comparison with those included in the control group. The results will be published as a manuscript. (4) Conclusions: This study aims to provide evidence on the effectiveness of home-based respiratory muscle training in enhancing swallowing function and respiratory parameters in patients with chronic stroke. Full article

Freedom of movement of the hands is the most desired hope of stroke patients. However, stroke recovery is a long, long road for many patients. If artificial intelligence can assist human arm movement, the possibility of stroke patients returning to normal hand movement might be significantly increased. This study uses the artificial neuromolecular system (ANM system) developed in our laboratory as the core of motion control, in an attempt to learn to control the mechanical arm to produce actions similar to human rehabilitation training and the transition between different activities. This research adopts two methods. The first is hypothetical exploration, the so-called “artificial world” simulation method. The detailed approach uses the V-REP (Virtual Robot Experimentation Platform) to conduct different experimental runs to capture relevant data. Our policy is to establish an action database systematically to a certain extent. From these data, we use the ANM system with self-organization and learning capabilities to develop the relationship between these actions and establish the possibility of conversion between different activities. The second method of this study is to use the data from a hospital in Toronto, Canada. Our experimental results show that the ANM system can continuously learn for problem-solving. In addition, our three experimental results of adaptive learning, transfer learning, and cross-task learning further confirm that the ANM system can use previously learned systems to complete the delivered tasks through autonomous learning (instead of learning from scratch). Full article

Magnetorheological finishing (MRF) of aspherical optical elements usually requires the coordination between the translational axes and the oscillating axes of the machine tool to realize the processing. For aspheric optical elements whose steepness exceeds the machining stroke of the equipment, there is still no better method to achieve high-precision and high-efficiency error convergence. To solve this problem, an MRF method combining virtual-axis technology and a spiral scanning path is proposed in this paper. Firstly, the distribution law of the magnetic induction intensity inside the polishing wheel is analyzed by simulation, the stability of the removal efficiency of the removal function within the ±7^∘ angle of the normal angle of the polishing wheel is determined, and MRF is expanded from traditional single-point processing to circular arc segment processing. Secondly, the spiral scanning path is proposed for aspherical rotational symmetric optical elements, which can reduce the requirements of the number of machine tool axes and the dynamic performance of machine tools. Finally, an aspherical fused silica optical element with a curvature radius of 400 mm, K value of −1, and aperture of 100 mm is processed. The PV value of this optical element converges from 189.2 nm to 24.85 nm, and the RMS value converges from 24.85 nm to 5.74 nm. The experimental results show that the proposed combined process has the ability to modify curved optical elements and can be applied to ultra-precision machining of high-steepness optical elements. Full article

Brain-computer interface (BCI) provides direct communication and control between the human brain and physical devices. It is achieved by converting EEG signals into control commands. Such interfaces have significantly improved the lives of disabled individuals suffering from neurological disorders—such as stroke, amyotrophic lateral sclerosis (ALS), and spinal cord injury—by extending their movement range and thereby promoting self-independence. Brain-controlled mobile robots, however, often face challenges in safety and control performance due to the inherent limitations of BCIs. This paper proposes a shared control scheme for brain-controlled mobile robots by utilizing fuzzy logic to enhance safety, control performance, and robustness. The proposed scheme is developed by combining a self-learning neuro-fuzzy (SLNF) controller with an obstacle avoidance controller (OAC). The SLNF controller robustly tracks the user’s intentions, and the OAC ensures the safety of the mobile robot following the BCI commands. Furthermore, SLNF is a model-free controller that can learn as well as update its parameters online, diminishing the effect of disturbances. The experimental results prove the efficacy and robustness of the proposed SLNF controller including a higher task completion rate of 94.29% (compared to 79.29%, and 92.86% for Direct BCI and Fuzzy-PID, respectively), a shorter average task completion time of 85.31 s (compared to 92.01 s and 86.16 s for Direct BCI and Fuzzy-PID, respectively), and reduced settling time and overshoot. Full article

Arginases are key enzymes that hydrolyze L-arginine to urea and L-ornithine in the urea cycle. The two arginase isoforms, arginase 1 (ARG1) and arginase 2 (ARG2), regulate the proliferation of cancer cells, migration, and apoptosis; affect immunosuppression; and promote the synthesis of polyamines, leading to the development of cancer. Arginases also compete with nitric oxide synthase (NOS) for L-arginine, and their participation has also been confirmed in cardiovascular diseases, stroke, and inflammation. Due to the fact that arginases play a crucial role in the development of various types of diseases, finding an appropriate candidate to inhibit the activity of these enzymes would be beneficial for the therapy of many human diseases. In this review, based on numerous experimental, preclinical, and clinical studies, we provide a comprehensive overview of the biological and physiological functions of ARG1 and ARG2, their molecular mechanisms of action, and affected metabolic pathways. We summarize the recent clinical trials’ advances in targeting arginases and describe potential future drugs. Full article

Matrix metalloproteinases (MMPs) such as MMP-9, 3, and 2 degrade the cellular matrix and are believed to play a crucial role in ischemic stroke. We examined how the duration of ischemia (up to 4 h) and treatment with recombinant tissue plasminogen activator altered the comparative expression of these MMPs in experimental ischemic stroke with reperfusion. Both prolonged ischemia and r-tPA treatment markedly increased MMP-9 expression in the ischemic hemisphere (all p < 0.0001). The duration of ischemia and r-tPA treatment also significantly increased MMP-2 expression (p < 0.01–0.001) in the ischemic hemisphere (p < 0.01) but to a lesser degree than MMP-9. In contrast, MMP-3 expression significantly decreased in the ischemic hemisphere (p < 0.001) with increasing duration of ischemia and r-tPA treatment (p < 0.05–0001). MMP-9 expression was prominent in the vascular compartment and leukocytes. MMP-2 expression was evident in the vascular compartment and MMP-3 in NeuN+ neurons. Prolonging the duration of ischemia (up to 4 h) before reperfusion increased brain hemorrhage, infarction, swelling, and neurologic disability in both saline-treated (control) and r-tPA-treated mice. MMP-9 and MMP-2 expression were significantly positively correlated with, and MMP-3 was significantly negatively correlated with, infarct volume, swelling, and brain hemorrhage. We conclude that in experimental ischemic stroke with reperfusion, the duration of ischemia and r-tPA treatment significantly altered MMP-9, 3, and 2 expression, ischemic brain injury, and neurological disability. Each MMP showed unique patterns of expression that are strongly correlated with the severity of brain infarction, swelling, and hemorrhage. In summary, in experimental ischemic stroke in male mice with reperfusion, the duration of ischemia, and r-tPA treatment significantly altered the immunofluorescent expression of MMP-9, 3, and 2, ischemic brain injury, and neurological disability. In this model, each MMP showed unique patterns of expression that were strongly correlated with the severity of brain infarction, swelling, and hemorrhage. Full article

Introduction: Apraxia is a neurological disorder that is common after a stroke and impairs the planning and execution of movements. In the rehabilitation field, virtual reality (VR) presents new opportunities and offers advantages to both rehabilitation teams and individuals with neurological conditions. Indeed, VR can stimulate and improve cognitive reserve and abilities, including executive function, and enhance the patient’s emotional status. Aim: The objective of this research is to determine the effectiveness of VR in improving praxis skills and behavioural functioning in individuals with severe stroke. Methods: A total of 20 stroke patients were enrolled from February 2022 to March 2023 and divided by the order of their recruitment into two groups: the experimental group (EG: n = 10) received training to improve their praxis skills using VR whereas the control one (CG: n = 10) received the same amount of standard training. All patients underwent an evaluation using a psychometric battery that consisted of the Hamilton Rating Scale for Depression (HRS-D), Mini-Mental State Examination (MMSE), Frontal Assessment Battery (FAB), Spinnler and Tognoni test, and De Renzi and Faglioni test. Valuations were performed before rehabilitation (T0) and after its completion (T1). Results: Both groups demonstrated significant improvements post-intervention. The EG showed a greater enhancement in their MMSE scores (p = 0.002), and reductions in both ideomotor and constructive apraxia (p = 0.002 for both), compared to the CG. The VR-based training also resulted in significant improvements in their depression symptoms (HRSD scores improved, p = 0.012 in EG vs. p = 0.021 in CG). Conclusions: This pilot study suggests that VR could help reduce cognitive, constructive apraxia and ideomotor apraxia symptoms caused by stroke injury. Full article

Background: Art therapy has a long history of applications in cognitive and motor rehabilitation. More recently, a growing body of scientific literature has highlighted the potential of virtual reality in neurorehabilitation, though it has focused more on the technology itself than on the principles adopted in digital scenarios. Methods: This study is a single-blind randomized controlled trial conducted on 40 patients with stroke, comparing conventional therapy (physical therapy for the upper and lower limbs, for posture and balance, cognitive therapy, occupational therapy, speech therapy, and specific therapy for swallowing, bowel, and bladder dysfunctions) to a protocol in which the upper limb physical therapy was substituted with art therapy administered by means of virtual reality exploiting the so-called Michelangelo effect. Results: After 12 sessions, patients in the virtual art therapy group showed a significantly greater improvement in independence in activities of daily living, as assessed by the Barthel Index (interaction of time and group: p = 0.001). Significant differences were also found in terms of upper limb muscle strength (Manual Muscle Test, p < 0.01) and reduction in spasticity (Ashworth scale, p = 0.007) in favor of the experimental group. In the virtual art therapy group, the effectiveness of the intervention was significantly correlated with patient participation (Pittsburgh Rehabilitation Participation Scale: R = 0.41), patient satisfaction (R = 0.60), and the perceived utility of the intervention by the therapist (R = 0.43). Conclusions: These findings support the efficacy of virtual art therapy leveraging the Michelangelo effect. Further studies should also focus on cognitive domains that could benefit from this type of approach. Full article

Glutaminyl cyclase (QC) and its isoenzyme (isoQC) catalyze the formation of N-terminal pyroglutamate (pGlu) from glutamine on a number of neuropeptides, peptide hormones and chemokines. Chemokines of the C-C ligand (CCL) motif family are known to contribute to inflammation in neurodegenerative conditions. Here, we used a model of transient focal cerebral ischemia to explore functional, cellular and molecular responses to ischemia in mice lacking genes for QC, isoQC and their substrate CCL2. Mice of the different genotypes were evaluated for functional consequences of stroke, infarct volume, activation of glia cells, and for QC, isoQC and CCL2 expression. The number of QC-immunoreactive, but not of isoQC-immunoreactive, neurons increased robustly in the infarct area at 24 and 72 h after ischemia. In parallel, immunohistochemical signals for the QC substrate CCL2 increased from 24 to 72 h after ischemia induction without differences between genotypes analyzed. The increase in CCL2 was accompanied by morphological activation of Iba1-immunoreactive microglia and recruitment of MHC-II-positive cells at 72 h after ischemia. Among other chemokines quantified in the brain tissue, CCL17 showed higher concentrations at 72 h compared to 24 h after ischemia. Collectively, these data suggest a critical role for QC in inflammatory processes in the stroke-affected brain. Full article

Background: Stroke survivors experience significant alterations in their daily functionality that has a negative impact on their functionality, participation, and quality of life. Person-centered approaches in Physical Therapy interventions that are focused on functional and meaningful goals help to minimize the impact of the alterations. Therefore, the aim of this study is to assess the effectiveness of a Physical Therapy intervention based on a goal-oriented approach with task-specific training for improving functionality, participation, and quality of life for people with Stroke. Methods: A single-blinded randomized controlled clinical trial will be developed. Adults over 50 years old diagnosed with Stroke over 6 months will be included in this study. Participants (n = 62) will be randomly allocated into two groups: The experimental group (n = 31) will receive 30 sessions, three per week during 10 weeks, of Physical Therapy sessions of goal-directed and task-specific training. The control group (n = 31) will follow the same intervention intensity of their usual Physical Therapy treatment. The primary outcome variables quality of life (NewsQol), participation (Ox-PAQ), and gait functionality (FAC) and the secondary outcome variables functional disability (BI), postural control (PASS), dynamic trunk balance (TIS), and functional goals (GAS) will be measured at baseline, after group interventions (10 weeks), and 6 months after the baseline. Statistical analyses will include repeated-measures ANOVA, Student’s t-test, or the Mann–Whitney U-test, with a 95% confidence interval and significance level of p < 0.05. Conclusion: Person-centered approaches in Physical Therapy interventions may yield better outcomes in functionality, participation, and quality of life for Stroke patients compared to standardized interventions. Trial registration: ClinicalTrials.gov: NCT06165666 (December 2023). Full article