Distinct Motion Patterns Research Articles

Magnetic alginate microrobots with dual-motion patterns through centrifugally driven flow control

Mobile microrobots have gained increasing attention in biomedical applications because they can be precisely actuated to targeted positions in a tiny space. However, their use in biomedical applications is hindered by the costly and complicated fabrication method. Herein, a facile fabrication method is proposed to produce magnetic alginate microrobots with adjustable dimensions, including teardrop and tadpole shapes, via tunable centrifugally-driven flows. The formation of these microrobots is interpreted by finite element analysis, revealing that the transition between the dripping and jetting regimes of the flow alters the microrobot's shape. The dimensions of the microrobots are quantitatively analyzed based on the flow's extrusion velocity, controlled by nozzle diameters and revolution speeds. Incorporating magnetic nanoparticles into the alginate-based hydrogel enables the microrobots to exhibit distinct motion patterns under a magnetic field. The teardrop-like microrobot can reach a maximum rolling velocity of approximately 2.7 body length s−1 at 2 Hz, while the maximum stick-slip velocity of the tadpole-like microrobot reaches about 0.42 body length s−1 at 5 Hz, comparable to the existing bioinspired magnetic microrobots. These two motion patterns allow the microrobot to overcome obstacles and navigate in vertically constrained environments, respectively. Last, an ultrasound imaging system is deployed to monitor the locomotion and degradation of the microrobots, showing their potential for targeted drug delivery applications.

Compliance Modeling and Kinetostatic Analysis of a Generalized 3-PSS Compliant Parallel Micro-Motion Platform.

In order to expand the range of motion performance of the 3-PSS-compliant parallel micro-motion platform, a variable inclination angle of the mechanism's guide rails was introduced to construct a category of generalized 3-PSS compliant parallel micro-motion platforms with distinct configurations (exhibiting different motion performances) but identical motion patterns (three translational degrees of freedom). The compliance and kinetostatics of such micro-motion platform are modeled and analyzed. Firstly, the compliance model is established based on the coordinate transformation method. Then, simplifying the micro-motion platform into a spring system, the kinetostatic model in terms of input force-output displacement is established based on the compliance model using the compliance matrix method. For practical application considerations, the kinetostatic model in terms of input displacement-output displacement is further derived based on the input force-output displacement model. Then, the correctness of the established compliance model and kinetostatic model is successively verified through finite element simulation. Finally, using two specified motion trajectories (spatial spiral trajectory and planar circular trajectory) as examples, an analysis is conducted on the influence of guide rail inclination angle variations on the kinetostatic performance of the micro-motion platform. This analysis serves as guidance for the rational design of such micro-motion platforms.

Experimental analysis of water-droplet–fiber interaction on a mechanically excited hydrophobic fiber

In this study, the dynamics of a single water droplet on a mechanically excited single fiber are investigated fundamentally. By utilizing state-of-the-art high-speed camera technology, the droplet's motion is captured with exceptional temporal resolution, enabling a detailed analysis of its position, size, and kinetics. We can identify distinct motion patterns of a droplet adhering to the fiber, which can exhibit either a static, a tilting, or swinging motion. The swinging and tilting motion can be overlaid with a higher-frequency deformation in response to the fiber excitation. Additionally, we examine the detachment of the droplet from the fiber as well as for the first time the (periodic) reattachment resulting from the mechanical excitation. The used droplet volumes are smaller, and the excitation shown here is greater than the excitation acceleration previously investigated in single fiber studies. Insights into droplet–fiber interactions can provide a better understanding of the mechanisms occurring in coalescence filters in harsh environments, which cannot be observed in situ with high temporal and spacial resolution in a full-scale filter due to the lack of optical access.

Self-Rotation of Electrothermally Responsive Liquid Crystal Elastomer-Based Turntable in Steady-State Circuits.

Self-excited motions, characterized by their ability to harness energy from a consistent environment and self-regulate, exhibit significant potential in micro-devices, autonomous robotics, sensor technology, and energy generation. This study introduces an innovative turntable system based on an electrothermally responsive liquid crystal elastomer (LCE). This system facilitates self-rotation within a steady-state circuit. Employing an electrothermal LCE model, we have modeled and numerically analyzed the nonlinear dynamics of an LCE-rope within steady-state circuits, utilizing the four-order Runge-Kutta method for calculations. The numerical results reveal the emergence of two distinct motion patterns in the turntable system under steady-state conditions: a self-rotation pattern and a static pattern. The self-rotation is initiated when the system's absorbed energy surpasses the energy lost due to damping effects. Furthermore, this paper delves into the critical conditions necessary for initiating self-rotation and examines the influence of various key dimensionless parameters on the system's rotation amplitude and frequency. These parameters include gravitational acceleration, the initial position of the mass ball, elastic stiffness of the LCE and spring, limiting temperature, heating zone angle, thermal shrinkage coefficient, and damping factor. Our computational findings establish that these parameters exert a modulatory impact on the rotation amplitude and period. This research enhances the understanding of self-excited motions and offers promising avenues for applications in energy harvesting, monitoring, soft robotics, medical devices, and micro- and nano-devices.

Cardiac MRI of characteristic motion findings in right bundle branch block.

While there have been many descriptions of characteristic motion findings in left bundle branch block (LBBB), there are few published descriptions of such findings in right bundle branch block (RBBB).The purpose of this study was to assess the frequency of particular regional motion findings in cardiac magnetic resonance imaging (CMR) studies of patients with RBBB, compared with normal subjects. We focused on three distinctive motion patterns that can be seen in RBBB during early systole: delayed apex-ward motion of the RV base, "reverse septal flash", and "basal bulge". The presence and relative magnitude of these findings were independently scored by four experienced observers, in 3-chamber and 4-chamber CMR cines, for both normal subjects and patients with RBBB. These motion patterns were found to be strongly associated with the presence of RBBB. While only moderately sensitive, they were quite specific for RBBB, when present. In particular, with ROC analysis, a combined feature set of the findings in the 4-chamber view had an area under the curve of 0.81.This previously undescribed set of RBBB-associated early-systolic regional motion features (delayed apex-ward motion of the RV base, "reverse septal flash", and "basal bulge") is strongly suggestive of RBBB when present, particularly in the 4-chamber view. Although here evaluated with CMR, it is also likely to be associated with RBBB when seen with other cardiac imaging modalities.

Microfluidic Design of Streamlined Alginate Hydrogel Micromotors with Run and Tumble Motion Patterns.

Autonomous micromotors demonstrate remarkable advancements in biomedical applications. A noteworthy example is streamlined motors, which display enhanced movement efficiency with low fluid-resistance. However, existing streamlined motors, primarily constructed from inorganic materials, present challenges due to their complex fabrication procedures and lack of a soft interface for interaction with biological systems. Herein, a novel design of biodegradable streamlined alginate hydrogel micromotors with a teardrop shape by microfluidics is introduced. The platform enables the high-throughput fabrication of monodisperse micromotors with varied dimensions. By incorporating Pt-coated Fe3 O4 nanoparticles, micromotors are equipped with dual capabilities of catalytic propulsion and accurate magnetic guidance. Through precisely tuning the localization regions of catalysts within the micromotors, the streamlined hydrogel micromotors not only exhibit enhanced propelling efficiency, but also accomplish distinct motion patterns of run and tumble. The design provides insights for developing advanced micromotors capable of executing intricate tasks across diverse application scenarios.

Comparative Analysis of Custom-Designed Soft Pneumatic Actuators for Human Thumb Movement in Post-Stroke Rehabilitation

One of the most potential applications of soft actuator is as wearable medical devices for post-stroke rehabilitation as a field that requires high levels of safety and adaptability. Incorporating SPAs into such devices can provide a safer and more secure solution, ensuring controlled movements that do not pose a risk to patients. However, there is a research gap regarding the design considerations for soft actuators specifically targeting the human thumb, which exhibits distinct motion patterns compared to the other fingers. This paper addresses this gap by developing and evaluating custom-designed SPAs for the movement of the human thumb, with a focus on post-stroke rehabilitation. Three SPA models (M1, M2, and M3) were proposed, and their performance in replicating the twisting motion of the thumb was assessed. The SPAs were fabricated using 3D printing, and image processing software was utilized for measurement and analysis. The results showed that the M3 model, with two sections of chambers in different axes, exhibited the best performance in generating the desired twisting angle. Integration of the M3 model with four finger-shaped SPAs enabled successful grasping and picking-like movements. This research contributes to the advancement of soft actuators in wearable medical devices, particularly in post-stroke rehabilitation, and holds promise for enhancing patient recovery and quality of life.

Doppler radar remote sensing of respiratory function.

Doppler radar remote sensing of torso kinematics can provide an indirect measure of cardiopulmonary function. Motion at the human body surface due to heart and lung activity has been successfully used to characterize such measures as respiratory rate and depth, obstructive sleep apnea, and even the identity of an individual subject. For a sedentary subject, Doppler radar can track the periodic motion of the portion of the body moving as a result of the respiratory cycle as distinct from other extraneous motions that may occur, to provide a spatial temporal displacement pattern that can be combined with a mathematical model to indirectly assess quantities such as tidal volume, and paradoxical breathing. Furthermore, it has been demonstrated that even healthy respiratory function results in distinct motion patterns between individuals that vary as a function of relative time and depth measures over the body surface during the inhalation/exhalation cycle. Potentially, the biomechanics that results in different measurements between individuals can be further exploited to recognize pathology related to lung ventilation heterogeneity and other respiratory diagnostics.

Dynamic Face Perception: The Role of Expertise in Dual Processing of Features and Configuration

Face perception is the basis of many types of social information exchange, but there is controversy over its underlying mechanisms. Researchers have theorized two processing pathways underlying facial perception: configural processing and featural processing. Featural processing focuses on the individual features of a face, whereas configural processing focuses on the spatial relations of features. To resolve the debate on the relative contribution of the two pathways in face perception, researchers have proposed a dual processing model that the two pathways contribute to two different perceptions, detecting face-like patterns and identifying individual faces. The dual processing model is based on face perception experiments that primarily use static faces. As we mostly interact with dynamic faces in real life, the generalization of the model to dynamic faces will advance our understanding of how faces are perceived in real life. This paper proposes a refined dual processing model of dynamic face perception, in which expertise in dynamic face perception supports identifying individual faces, and it is a learned behaviour that develops with age. Specifically, facial motions account for the advantages of dynamic faces, compared to static faces. This paper highlights two intrinsic characteristics of facial motions that enable the advantages of dynamic faces in face perception. Firstly, facial motion provides facial information from various viewpoints, and thus supports the generalization of face perception to the unlearned view of faces. Secondly, distinctive motion patterns serve as a cue to the identity of the face.

Resolving immune cells with patrolling behaviour by magnetic resonance time-lapse single cell tracking.

BackgroundImmune cells show distinct motion patterns that change upon inflammatory stimuli. Monocytes patrol the vasculature to screen for pathogens, thereby exerting an early task of innate immunity. Here, we aimed to non-invasively analyse single patrolling monocyte behaviour upon inflammatory stimuli.MethodsWe used time-lapse Magnetic Resonance Imaging (MRI) of the murine brain to dynamically track single patrolling monocytes within the circulation distant to the actual site of inflammation in different inflammatory conditions, ranging from a subcutaneous pellet model to severe peritonitis and bacteraemia.FindingsSingle patrolling immune cells with a velocity of <1 µm/s could be detected and followed dynamically using time-lapse MRI. We show, that due to local and systemic stimuli the slowly patrolling behaviour of monocytes is altered systemically and differs with type, duration and strength of the underlying stimulus.InterpretationUsing time-lapse MRI, it is now possible to investigate the behaviour of single circulating monocytes over the course of the systemic immune response. Monocyte patrolling behaviour is altered systemically even before the onset of clinical symptoms distant to and depending on the underlying inflammatory stimulus.FundingThis study was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - CRC 1009 - 194468054 to AZ, CF and - CRC 1450 - 431460824 to MM, SN, HB, AZ, CF, the Joachim Herz Foundation (Add-on Fellowship for Interdisciplinary Life Sciences to MM), the Interdisciplinary Centre for Clinical Research (IZKF, core unit PIX) and the Medical Faculty of the University of Muenster (MEDK fellowship to FF and IF).

A novel modelling and simulation approach for the hindered mobility of charged particles in biological hydrogels

This article presents a novel computational model to study the selective filtering of biological hydrogels due to the surface charge and size of diffusing particles. It is the first model that includes the random three-dimensional fibre orientation and connectivity of the biopolymer network and that accounts for elastic deformations of the fibres by means of beam theory. As a key component of the model, novel formulations are proposed both for the electrostatic and repulsive steric interactions between a spherical particle and a beam. In addition to providing a thorough validation of the model, the presented computational studies yield new insights into the underlying mechanisms of hindered particle mobility, especially regarding the influence of the aforementioned aspects that are unique to this model. It is found that the precise distribution of fibre and thus charge agglomerations in the network have a crucial influence on the mobility of oppositely charged particles and gives rise to distinct motion patterns. Considering the high practical significance for instance with respect to targeted drug release or infection defence, the provided proof of concept motivates further advances of the model towards a truly predictive computational tool that allows a case- and patient-specific assessment for real (biological) systems.

Context-sensitive smart glasses monitoring wear position and activity for therapy compliance-A proof of concept.

PurposeTo improve the acceptance and compliance of treatment of amblyopia, the aim of this study was to show that it is feasible to design an electronic frame for context-sensitive liquid crystal glasses, which can measure the state of wear position in a robust manner and detect distinct motion patterns for activity recognition.MethodsDifferent temple designs with integrated temperature and capacitive sensors were developed to realize the detection of the state of wear position to distinguish three states (correct position/wrong position/glasses taken off). The electronic glasses frame was further designed as a tool for accelerometer data acquisition, which was used for algorithm development for activity classification. For this purpose, training data of 20 voluntary healthy adult subjects (5 females, 15 males) were recorded and a 10-fold cross-validation was computed for classifier selection. In order to perform functional testing of the electronic glasses frame, a proof of concept study was performed in a small group of healthy adults. Four healthy adult subjects (2 females, 2 males) were included to wear the electronic glasses frame and to protocol their activities in their everyday life according to a defined test protocol. Individual and averaged results for the precision of the state of wear position detection and of the activity recognition were calculated.ResultsContext-sensitive control algorithms were developed which detected the state of wear position and activity in a proof of concept. The pilot study revealed an average of 91.4% agreement of the detected states of wear position. The activity recognition match was 82.2% when applying an additional filter criterion. Removing the glasses was always detected 100% correctly.ConclusionThe principles investigated are suitable for detecting the glasses’ state of wear position and for recognizing the wearer´s activity in a smart glasses concept.

Comparing patient-reported outcome measures and physical examination for internal rotation in patients undergoing reverse shoulder arthroplasty: does surgery alter patients' perception of function?

The purpose of this study was to evaluate how patients treated with reverse shoulder arthroplasty (RSA) achieve internal rotation (IR) using video assessment and to compare this to patient-reported outcome measures (PROMs). We reviewed 215 preoperative and 657 postoperative videos (3-78 months) for 215 patients who underwent primary RSA, performing IR using the modified vertebral level method. Their functional motion pattern was then grouped into 3 types: type I, could not reach behind their back; type II, able to reach to at least waist level, with assistance; and type III, able to reach to a minimum of waist level in an uninterrupted fashion. Patients completed functional questions (put on a coat, wash back, tuck in a shirt, and manage toileting) and a diagram of perceived IR. Patients' functional motion types were compared to PROM answers. Pre- and postoperative scores were also compared to assess the effect of surgery on patients' perception of IR function. Patients undergoing RSA will achieve IR in 3 distinct motion patterns. Analysis of self-reported IR indicated statistically significant difference between the 3 functional types of IR (P < .001). Patient-perceived IR was not significantly different between the 3 studied IR functional types (P = .076) in the analysis of preoperative measures but was significantly different in the postoperative setting (P < .001). Patients attempt IR in 3 distinct functional motion patterns. The improvement of IR after RSA is measured better by patient questionnaires than by physical examination.

Spiral Arm Pattern Motion in the SAO 206462 Protoplanetary Disk

Abstract Spiral arms have been observed in more than a dozen protoplanetary disks, yet the origin of nearly all systems is under debate. Multi-epoch monitoring of spiral arm morphology offers a dynamical way to distinguish two leading arm formation mechanisms: companion-driven and gravitational instability induction, since these mechanisms predict distinct motion patterns. By analyzing multi-epoch J-band observations of the SAO 206462 system using the SPHERE instrument on the Very Large Telescope in 2015 and 2016, we measure the pattern motion for its two prominent spiral arms in polarized light. On one hand, if both arms are comoving, they can be driven by a planet at au on a circular orbit, with gravitational instability motion ruled out. On the other hand, they can be driven by two planets at au and au, offering tentative evidence (3.0σ) that the two spirals are moving independently. The independent arm motion is possibly supported by our analysis of a re-reduction of archival observations using the NICMOS instrument on board the Hubble Space Telescope (HST) in 1998 and 2005, yet artifacts including shadows can manifest spurious arm motion in HST observations. We expect future re-observations to better constrain the motion mechanism for the SAO 206462 spiral arms.

Kinematic MRI of ischiofemoral impingement.

To examine the effect of external hip rotation on ischiofemoral (IF) and quadratus femoris (QF) spaces using real-time kinematic MRI, with the hypothesis that hips with IF and QF space narrowing have distinct motion patterns compared with control hips. This prospective study was IRB-approved and complied with HIPAA guidelines. We recruited women (≥ 18years) with and without ischiofemoral impingement to undergo kinematic MRI of the hips. A kinematic imaging protocol using T2-HASTE was performed beginning at maximal internal rotation followed by active external hip rotation. The duration of each acquisition was 30s, providing 8 images/3s. IF and QF spaces, and femoral metaphyseal and lesser trochanter centroid coordinates were measured on sequential images. Hips were classified as controls or narrowed based on IF and QF space thresholds and compared statistically throughout motion stages. The cohort comprised 12 women (24 hips; 10 control and 14 narrowed hips) aged 58 ± 10years. External rotation caused IF space reduction of 59% in narrowed hips versus 41% in control hips. QF space decreased 71% in narrowed hips versus 50% in control hips. IF and QF spaces differed significantly between groups only when external rotation exceeded the neutral position (P< 0.02 for both). The lesser trochanter terminated more posteriorly in narrowed hips compared with controls (P= 0.03). Kinematic MRI during external hip rotation in women with narrowed and control hips reveals dynamic differences in IF and QF spaces and lesser trochanter terminal position.

Flexor pollicis longus tendon retrieval using silicone rods; is it worth it?

The hand represents one of the most common sites for injuries in a trauma setting. Hand mobility, the arc of motion away from the body, and being involved in many of the daily activities add to this high incidence. Thumb injuries carry a substantial burden on hand function due to its mobility, distinctive motion patterns, and particular purposes it attains. This is a prospective case-control study for cases presented to the emergency department at Kasr Al-Ainy, school of medicine, Cairo University, for the period between January 2018 and July 2019, with zone II (T2) flexor pollicis longus (FPL) tendon injuries. Patients were divided into two groups: one group had FPL retrieved with the aid of silicone rods using a different wrist incision and the other group had a retrieval done through the same site of injury without the use of rods. Patients were followed up paying attention to their rehabilitation progress, return-to-work time, and complications (e.g., rupture and infections). Patients with comorbidities (e.g., diabetes mellitus), hand infections, or associated fractures were excluded from the study. One hundred patients were included in this study. Randomly, 50 patients were assigned to group A and 50 patients to group B. The age range was 16 to 75 years. Eighty percent of the patients were males, and the remaining 20% were females. Follow-up period ranged from 3 months to 1 year with a mean follow-up period of 8 months. Group A showed shorter operative time (P value < 0.001), faster return to work (P value < 0.001), and lower complication rates (P value < 0.07) than group B. The use of silicone rods represents a suitable method for FPL tendon repair with faster recovery, lower complication rates, and shorter operative times. Level of evidence: Level IV, therapeutic study.

Coaxial Electrospinning: Jet Motion, Core–Shell Fiber Morphology, and Structure as a Function of Material Parameters

Two core–shell-structured polystyrene/poly(vinyl pyrrolidone) (PS/PVP) and PVP/PS composite fibers were prepared via coaxial electrospinning in this study. Different concentrations of PVP solutions with a variety of viscosities and conductivities were adopted in the experiment. The influences of both viscosity and conductivity on the Taylor cone, jet motion, morphology, and internal structure of the resultant core–shell fiber were investigated in a comprehensive and systematic manner. As shown in the images of Taylor cone and jet motion, which were captured by a high-speed camera, different PVP concentrations in the core and shell would result in different core and shell thicknesses as well as distinct jet motion patterns including straight jet length, envelop angle, and frequency of whipping process, thus obtaining the core–shell fibers with different diameters. Not only jet motion and Taylor cone but also the polymer solution concentration and the role of PVP in core and shell have a tremendous influence on the morphology and the internal structure of the resultant core–shell fiber. Additionally, the formation mechanisms of PS/PVP and PVP/PS fibers were studied by means of Fourier transform infrared (FTIR). The experimental results provide a basis for further design and optimization of processing conditions, so as to control the nanostructure of core–shell composite fibers.

Not just scratching the surface: distinct radular motion patterns in Mollusca.

ABSTRACTThe radula is the organ for mechanical food processing and an important autapomorphy of Mollusca. Its chitinous membrane, embedding small radular teeth, is moved by the set of muscles resulting in an interaction with the ingesta, tearing it and collecting loosened particles. Radulae and their teeth can be quite distinct in their morphology and had been of high research interest, but only a few studies have examined the basic functional principles of this organ, the movement and motion during feeding action. Here, the radular motion of 20 representative species, belonging to four major gastropod lineages (Vetigastropoda, Neritimorpha, Caenogastropoda and Heterobranchia) and Polyplacophora, were recorded and classified. Comparisons of the video footage with the scanning electron microscope (SEM) images of the radula resulted in the recognition of functional tooth rows and the correct position of the teeth during feeding. We identified six different types of radular movements, including rotations and bending of the radula itself. In each movement type, different structures act as counter bearings enabling the animals to grab and tear food.

The role of visual angle in pattern phase transition of collective motions

Abundant collective motion patterns of animal groups have different kinds of functions like migration, predator avoidance and foraging. To explore the phase transition mechanism behind such charming collective behaviors, some self-propelled particle models have been proposed, most of which however have isotropic inter-particle interactions and hence could not reproduce sophisticated natural collective patterns. As a remedy, this letter develops an anisotropic self-propelled particle model. By slightly tweaking the vision range and inter-particle attraction, the proposed model demonstrate transitions between four distinct collective motion patterns, i.e., torus, dumbbell, twist, and worm. To investigate more insightfully into the phase transition nature, quantitative analysis is carried out, revealing the relationship of visual angle-based inter-agent interactions and abundant pattern transitions existing in large numbers of natural, social and artificial grouping behaviors. From the industrial application point of view, the present study can help adjust the formation of multiple unmanned systems by simply tweaking a couple of vision-related parameters in their models.

Spatiotemporal Variability of Sea Ice in the Arctic's Last Ice Area

AbstractThe Arctic Ocean's oldest and thickest sea ice lies along the ~2,000 km arc from the western Canadian Arctic Archipelago to the northern coast of Greenland. Climate models suggest that this region will be the last to lose its perennial ice cover, thus providing an important refuge for ice‐dependent species. However, remarkably little is known about the climate or characteristics of the sea ice in this remote and inhospitable region. Here, we use the Pan‐Arctic Ice Ocean Modeling and Assimilation System model to show that the ice cover in the region is very dynamic, with changes occurring at a rate twice that of the Arctic Ocean as a whole. However, there are some differences in the changing nature of the ice cover between the eastern and western regions of the Last Ice Area, which include different timing of the annual minimum in ice thickness as well as distinct ice motion patterns associated with ice thickness extrema.