Vibratory Stimulation Research Articles

Nanovibrational Stimulation of Escherichia coli Mitigates Surface Adhesion by Altering Cell Membrane Potential.

Mechanical forces shape living matter from the macro- to the microscale as both eukaryotic and prokaryotic cells are force wielders and sensors. However, whereas such forces have been used to control mechanically dependent behaviors in mammalian cells, we lack the same level of understanding in bacteria. Surface adhesion, the initial stages of biofilm formation and surface biofouling, is a mechanically dependent process, which makes it an ideal target for mechano-control. In this study, we employed nanometer surface vibrations to mechanically stimulate bacteria and investigate their effect on adhesion. We discovered that vibrational stimulation at the nanoscale consistently reduces surface adhesion by altering cell membrane potential. Our findings identify a link between bacteria electrophysiology and surface adhesion and provide evidence that the nanometric mechanical "tickling" of bacteria can inhibit surface adhesion.

Wearable Online Freezing of Gait Detection and Cueing System.

This paper presents a real-time wearable system designed to assist Parkinson's disease patients experiencing freezing of gait episodes. The system utilizes advanced machine learning models, including convolutional and recurrent neural networks, enhanced with past sample data preprocessing to achieve high accuracy, efficiency, and robustness. By continuously monitoring gait patterns, the system provides timely interventions, improving mobility and reducing the impact of freezing episodes. This paper explores the implementation of a CNN+RNN+PS machine learning model on a microcontroller-based device. The device operates at a real-time processing rate of 40 Hz and is deployed in practical settings to provide 'on demand' vibratory stimulation to patients. This paper examines the system's ability to operate with minimal latency, achieving an average detection delay of just 261 milliseconds and a freezing of gait detection accuracy of 95.1%. While patients received on-demand stimulation, the system's effectiveness was assessed by decreasing the average duration of freezing of gait episodes by 45%. These preliminarily results underscore the potential of personalized, real-time feedback systems in enhancing the quality of life and rehabilitation outcomes for patients with movement disorders.

Effect of closed-loop vibration stimulation on sleep quality for poor sleepers.

Recent studies have investigated the autonomic modulation method using closed-loop vibration stimulation (CLVS) as a novel strategy for enhancing sleep quality. This study aimed to explore the effects of CLVS on sleep quality, autonomic regulation, and brain activity in individuals with poor sleep quality. Twenty-seven participants with poor sleep quality (Pittsburgh sleep quality index >5) underwent two experimental sessions using polysomnography and a questionnaire, one with CLVS (STIM) and the other without (SHAM). Sleep macrostructure analysis first showed that CLVS significantly reduced the total time, proportion, and average duration of waking after sleep onset. These beneficial effects were paralleled by significantly increased self-reported sleep quality. Moreover, there was a significant increase in the normalized high-frequency (nHF) and electroencephalography relative powers of delta activity during N3 sleep under STIM. Additionally, coherence analysis between nHF and delta activity revealed strengthened coupling between cortical and cardiac oscillations. This study demonstrated that CLVS significantly improves sleep quality in individuals with poor sleep quality by enhancing both subjective and objective measures. These findings suggest that CLVS has the potential to be a practical, noninvasive tool for enhancing sleep quality in individuals with sleep disturbances, offering an effective alternative to pharmacological treatments.

Specific Contribution of the Transversus Abdominis for Postural Control Against Perturbation Caused by Kinesthetic Illusion.

Functional independence of the transversus abdominis (TrA) from other trunk muscles for postural control is still unclear. This study aimed to clarify the specific function of the TrA to control standing posture by vibratory stimulation of the triceps surae. Fifteen men participated in this study. Muscle activity of the TrA, internal oblique, lumbar multifidus, gluteus maximus, rectus femoris, biceps femoris, gastrocnemius, and tibialis anterior was measured using fine-wire and surface electrodes. Participants were asked to maintain a quiet standing posture with and without vibration of the triceps surae, which induced a kinesthetic illusion and the concomitant backward sway of the body. The muscle activity of each muscle for 10s was extracted with and without vibration. The muscle activity levels were compared between the conditions by a paired t-test or Wilcoxon signed-rank test. The activity of the TrA and rectus femoris was increased, whereas the internal oblique showed no change as a result of the induced kinesthetic illusion. In addition, the activity of the multifidus and biceps femoris was decreased. The TrA and rectus femoris could contribute to control the backward sway of the body. Furthermore, the TrA may have functional independence from the internal oblique during standing postural control. These results warrant further study in patients with low back pain.

Effect of Whole-Body Vibration Versus Rhythmic Auditory Stimulation on Spasticity, Balance, and Lower Limb Motor Function in Hemiplegic Stroke Patients

Background: Stroke can lead to spasticity, balance impairments, and lower limb motor dysfunction. Whole-body vibration (WBV) and rhythmic auditory stimulation (RAS) are two therapeutic interventions that may address these deficits.Objective: To compare the effects of WBV and RAS on spasticity, balance, and lower limb motor function in hemiplegic stroke patients.Methods: A single-blinded, randomized controlled trial was conducted with 104 chronic hemiplegic stroke patients, divided into two groups: Group A (WBV) and Group B (RAS). WBV was applied using a vibration platform at 30-40 Hz for 3-minute sessions, 3 days/week for 4 weeks. RAS involved 90-minute sessions of music-based exercises, incorporating rhythmic cues and conventional therapy, 3 days/week for 4 weeks. Spasticity, balance, and motor function were assessed using the Modified Ashworth Scale, Berg Balance Scale, and Fugl-Meyer Assessment, respectively. Data were analyzed using SPSS version 27.Results: Group A showed greater improvements in spasticity (MAS: 1.2±0.4 vs. 2.6±0.3), balance (BBS: 49±5 vs. 43±5), and motor function (FMA: 29±5 vs. 18.5±5) compared to Group B (p<0.05).Conclusion: WBV is more effective than RAS in improving spasticity, balance, and motor function in chronic hemiplegic stroke patients.

Whole-body vibration versus gravity force stimulation on postural stability in children with Down syndrome: A randomized controlled trial

Purpose. To compare how functional walking ability and postural stability are affected in children with DS by whole-body vibration and gravity force stimulation. Methods. This study enrolled sixty DS children from both sexes into three groups at random. A structured physical therapy plan was given to the control and both study groups. Whole-body vibration (WBV) and gravity force stimulation (GFS) were given to the study groups (I) and (II) respectively. Postural stability indices (overall, mediolateral, and anteroposterior) and functional walking capacity were assessed by the Biodex balance system (BBS) and six-minute walk test (6MWT) respectively. The intervention session was conducted thrice/week for 12 consecutive weeks. Results. All stability indices at stability levels 8 and 5 significantly decreased after-intervention compared to before-intervention, but the 6MWT significantly increased in all three groups. All stability indices at stability levels 8 and 5 showed a significant decrease after-intervention, and the 6MWT in all three groups significantly increased in favor of study groups (WBV) and (GFS). However, there were no significant differences in all stability indices at stability levels 8 and 5 and in 6MWT between study groups (WBV) and (GFS) after-intervention. Conclusion. Whole-body vibration and gravity force stimulation both had a similar effect on postural stability and functional walking capacity among children who have Down syndrome.

Cathepsin K Expression is Upregulated Following Micropulse Vibration Stimulation of Osteoclasts Cultured in Vitro

Aim: To evaluate osteoclast inhibition following micropulse vibration and the effects of micropulse vibration on the expression of IL-1β, TNF-α, and RANKL in osteoblasts and osteoclasts and that of cathepsin K (CatK) in osteoclasts cultivated in vitro. Materials and methods: Primary murine osteoblasts and osteoclasts were cultured in vitro and stimulated with an AcceleDent Aura device for 20 min per day for 0 to 96 hours, with microvibrations of 0.25 N/30 Hz. Subsequently, the levels of IL-1β, TNF-α, and RANKL in the supernatants of the culture medium of both types of cells were measured by enzyme-linked immunosorbent assays (ELISAs). In addition, the level of CatK in osteoclasts was evaluated by flow cytometry. Results: Microvibrations significantly upregulated IL-1β and TNF-α expression and downregulated RANKL expression in osteoblasts compared with the corresponding expression in the control group. Compared to those in the control group, osteoclasts treated with microvibrations showed significant downregulation of IL-1β, TNF-α, and RANKL expression. CatK levels in stimulated osteoclasts were increased compared to those in the control group. Conclusion: The type of microvibration applied in this study inhibits osteoclastogenesis and upregulates the expression of CatK, an enzyme that induces bone matrix degradation in osteoclasts cultured in vitro, which stimulates bone formation by osteoblasts and accelerates bone mineralization.

Tough and self-adhesive zwitterionic hydrogels with mechano-responsive release of bFGF for tympanic membrane repair

The tympanic membrane (TM) is constantly in a state of vibrating. However, there is currently a lack of drug-delivery scaffolds suitable for the dynamic environment of TM perforation. In this study, a mechano-responsive tough hydrogel was developed. It consists of basic fibroblast growth factor (bFGF)-loaded sodium alginate (SA) microspheres, polysulfobetaine methacrylate (polySBMA), and gelatin methacrylate (GelMA). This hydrogel was designed to serve as a TM scaffold to promote perforation healing under dynamic conditions. bFGF was encapsulated in SA microspheres, which were then incorporated into polySBMA-GelMA hydrogels through photo-initiated free radical polymerization. The mechanical properties, tissue adhesiveness, swelling properties, and degradation of the hydrogels were evaluated before and after microsphere incorporation. It was observed that incorporating bFGF-loaded SA microspheres did not significantly impact the adhesion and degradation mechanisms of the hydrogel. The compressive strength and tensile strength of the microsphere-incorporated hydrogel were up to 6.6 MPa and 64.1 kPa, respectively, suitable for a TM scaffold. The release behavior of bFGF from the hydrogel could be controlled by vibration stimulation without significantly affecting the hydrogel's mechanical properties, indicating a mechano-responsive nature of the hydrogel. The in vitro cytotoxicity assay demonstrated that the hydrogels showed no cytotoxic effects. Moreover, cell culture assays demonstrated that vibration stimulation could enhance the release of bFGF, significantly promoting cell proliferation and migration. The results demonstrate the significant potential of the mechano-responsive hydrogel as a scaffold for repairing TM perforations.

Concurrent abnormalities in galvanic cervical and ocular vestibular-evoked myogenic potentials as a predictive marker for prolonged dizziness in vestibular neuritis

Background Despite the growing use of cervical (cVEMP) and ocular (oVEMP) VEMP tests, their effectiveness in predicting chronic dizziness in vestibular neuritis (VN) patients remains unclear. Our research examines the link between long-lasting dizziness and inner ear assessments, encompassing VEMPs induced by air-conducted sound (ACS), bone-conducted vibration (BCV), and galvanic vestibular stimulation (GVS). Objectives This study explores prognostic markers by examining the relationship between the persistence of dizziness symptoms and various inner ear test findings in VN patients. Material and methods A retrospective cohort of 60 unilateral VN patients underwent comprehensive audiovestibular tests, including pure tone audiometry, cVEMP and oVEMP induced by ACS, BCV, GVS, and caloric tests. Patient subgroups were established based on dizziness duration: short-term (<3 months) and long-term (≥3 months). Results No substantial correlation existed between the dizziness duration and the outcomes of any particular single inner ear test. However, patients exhibiting concurrent abnormal GVS-cVEMP and GVS-oVEMP were more likely to experience prolonged dizziness, indicating more extensive vestibular system involvement. Conclusions Concurrent abnormalities in GVS-cVEMP and GVS-oVEMP may indicate a higher chance of long-term dizziness in VN. Significance This study identifies concurrent abnormalities in GVS-cVEMP and GVS-VEMP as a potential prognostic marker for prolonged dizziness in VN.

Acute Effects of Handheld Vibration Massage on Posterior Shoulder Soft Tissues.

Interventions using vibration stimulation have been recognized for their potential for increasing range of motion (ROM) without compromising muscle strength. Handheld vibration massagers can efficiently deliver vibration therapy to the shoulder joint and may be a potential treatment. To evaluate the effects of vibration massage using a handheld device on the soft tissues of the posterior shoulder joint, particularly on internal rotation (IR) passive ROM and external rotation (ER) muscle strength. Crossover study design. A crossover study with a 5-min vibration massage and passive control condition was conducted in healthy male volunteers (mean age 20.5 ± 1.7 years). Vibration massage was applied to the posterior shoulder soft tissues of the dominant arm, with no intervention under control conditions. IR-ROM (vertebral level and in abduction) and strength of the external rotators (isometric and isokinetic) were measured before and immediately after the intervention. Vertebral levels were calculated as a ratio of lengths (ratio decreases with increased mobility). IR-ROM in abduction, the angle was measured. Statistical analysis was performed with two-way repeated measures ANOVA and paired t-test (Bonferroni correction). Vibration application decreased (improved) vertebral level IR ROM by -4.1% (p < 0.01, d = 0.445) and increased abduction position IR ROM by 11.4° (p < 0.01, d = 0.694). These changes exceeded the 95% confidence interval for the minimum detectable change. By contrast, the control condition produced no changes. IR-ROM (vertebral level and abduction) immediately after the intervention showed significant differences between the control and vibration conditions (p = 0.036, d = 0.273; p = 0.048, d = 0.483, respectively). Muscle strength did not show any interaction, time, or between-condition effects. A massage using a handheld vibration massager applied to the posterior shoulder soft tissues increased IR-ROM without negatively affecting muscle strength, suggesting its potential use as a means of warming up. Level 3.

Commentary on "Effects of upper limb vibratory stimulation training on motor symptoms in Parkinson's disease: an observational study".

Commentary on "Effects of upper limb vibratory stimulation training on motor symptoms in Parkinson's disease: an observational study".

Developing a tablet-based brain-computer interface and robotic prototype for upper limb rehabilitation.

The current study explores the integration of a motor imagery (MI)-based BCI system with robotic rehabilitation designed for upper limb function recovery in stroke patients. We developed a tablet deployable BCI control of the virtual iTbot for ease of use. Twelve right-handed healthy adults participated in this study, which involved a novel BCI training approach incorporating tactile vibration stimulation during MI tasks. The experiment utilized EEG signals captured via a gel-free cap, processed through various stages including signal verification, training, and testing. The training involved MI tasks with concurrent vibrotactile stimulation, utilizing common spatial pattern (CSP) training and linear discriminant analysis (LDA) for signal classification. The testing stage introduced a real-time feedback system and a virtual game environment where participants controlled a virtual iTbot robot. Results showed varying accuracies in motor intention detection across participants, with an average true positive rate of 63.33% in classifying MI signals. The study highlights the potential of MI-based BCI in robotic rehabilitation, particularly in terms of engagement and personalization. The findings underscore the feasibility of BCI technology in rehabilitation and its potential use for stroke survivors with upper limb dysfunctions.

Neurodevelopmental toxicity of a ubiquitous disinfection by-product, bromoacetic acid, in Zebrafish (Danio rerio)

Disinfection of public drinking water and swimming pools is crucial for preventing waterborne diseases, but it can produce harmful disinfection by-products (DBPs), increasing the risk of various diseases for those frequently exposed to such environments. Bromoacetic acid (BAA) is a ubiquitous DBP, with toxicity studies primarily focused on its in vitro cytotoxicity, and insufficient research on its neurodevelopmental toxicity. Utilizing zebrafish as a model organism, this study comprehensively explored BAA’s toxic effects and uncovered the molecular mechanisms through neurobehavioral analysis, in vivo two-photon imaging, transcriptomic sequencing, pharmacological intervention and molecular biological detection. Results demonstrated BAA induced significant changes on various indicators in the early development of zebrafish. Furthermore, BAA disrupted behavioral patterns in zebrafish larvae across locomotion activity, light-dark stimulation, and vibration stimulation paradigms. Subsequent investigation focused on larvae revealed BAA inhibited neuronal development, activated neuroinflammatory responses, and altered vascular morphology. Transcriptomic analysis revealed BAA-stressed zebrafish exhibited downregulation of visual transduction-related genes and activation of ferroptosis and cellular apoptosis. Neurobehavioral disorders were recovered by inhibiting ferroptosis and apoptosis. This study elucidates the neurodevelopmental toxicity associated with BAA, which is crucial for understanding health risks of DBPs and for the development of more effective detection methods and regulatory strategies.

Prevalence and Interventions for Behavioral Pathology in Spinal Cord Injury

AbstractSpinal cord injury (SCI) represents a significant life event for an individual, encompassing physiological, psychological, and social changes. The potentially traumatic or distressing nature of acquiring an SCI and the associated life changes that ensue following an injury can increase the risk of mental health concerns. This review aimed at identifying prevalence of behavioral pathologies and interventions following SCI across the world. To identify the articles of interest for this review, the search was narrowed by using the combination of search terms as follows: “Spinal Cord Injury”, “Depression,” “Anxiety,” “Psychological Impact,” “Quality of life,” and “Sexual dysfunction.” Prevalence of depression and anxiety was noted to be in the range of 7 to 47.7%. SCI patients were also commonly seen to be associated with sexual dysfunction. The pharmacological interventions included drugs such as phosphodiesterase inhibitors like sildenafil and tadalafil, whereas certain studies also mentioned a few devices like the penile vibratory stimulation and electroejaculation and vacuum erection devices. Apart from empowering and educating healthcare providers, neuromodulation has been shown to be an efficient treatment. Patients with SCIs have a suicide rate that is two to six times greater than that of general population. Effects of mindfulness on functional limitation and quality of life were promising. Guided Internet-delivered cognitive behavioral therapy showed improvement in depression and anxiety symptoms with appreciable adherence to therapy programs. Hyperbaric oxygen therapy showed improvement in depressed SCI patients.

Evaluating the effect of tissue stimulation at different frequencies on breast lesion classification based on nonlinear features using a novel radio frequency time series approach

ObjectiveRadio Frequency Time Series (RF TS) is a cutting-edge ultrasound approach in tissue typing. The RF TS does not provide dynamic insights into the propagation medium; when the tissue and probe are fixed. We previously proposed the innovative RFTSDP method in which the RF data are recorded while stimulating the tissue. Applying stimulation can unveil the mechanical characteristics of the tissue in RF echo. Materials and methodsIn this study, an apparatus was developed to induce vibrations at different frequencies to the medium. Data were collected from four PVA phantoms simulating the nonlinear behaviors of healthy, fibroadenoma, cyst, and cancerous breast tissues. Raw focused, raw, and beamformed ultrafast data were collected under conditions of no stimulation, constant force, and various vibrational stimulations using the Supersonic Imagine Aixplorer clinical/research ultrasound imaging system. Time domain (TD), spectral, and nonlinear features were extracted from each RF TS. Support Vector Machine (SVM), Random Forest, and Decision Tree algorithms were employed for classification. ResultsThe optimal outcome was achieved using the SVM classifier considering 19 features extracted from beamformed ultrafast data recorded while applying vibration at the frequency of 65 Hz. The classification accuracy, specificity, and precision were 98.44 ± 0.20 %, 99.49± 0.01 %, and 98.53± 0.04 %, respectively. Applying RFTSDP, a notable 24.45 % improvement in accuracy was observed compared to the case of fixed probe assessing the recorded raw focused data. ConclusionsExternal vibration at an appropriate frequency, as applied in RFTSDP, incorporates beneficial information about the medium and its dynamic characteristics into the RF TS, which can improve tissue characterization.

EEG correlates to perceived urgency elicited by vibration stimulation of the upper body

Conveying information effectively while minimizing user distraction is critical to human–computer interaction. As the proliferation of audio–visual communication pushes human information processing capabilities to the limit, researchers are turning their attention to haptic interfaces. Haptic feedback has the potential to create a desirable sense of urgency that allows users to selectively focus on events/tasks or process presented information with minimal distraction or annoyance. There is a growing interest in understanding the neural mechanisms associated with haptic stimulation. In this study, we aim to investigate the EEG correlates associated with the perceived urgency elicited by vibration stimuli on the upper body using a haptic vest. A total of 31 participants enrolled in this experiment and were exposed to three conditions: no vibration pattern (NVP), urgent vibration pattern (UVP), and very urgent vibration pattern (VUVP). Through self-reporting, participants confirmed that the vibration patterns elicited significantly different levels of perceived urgency (Friedman test, Holm–Bonferroni correction, p < 0.01). Furthermore, neural analysis revealed that the power spectral density of the delta, theta, and alpha frequency bands in the middle central area (C1, Cz, and C2) significantly increased for the UVP and VUVP conditions as compared to the NVP condition (One-way ANOVA test, Holm–Bonferroni correction, p < 0.01). While the perceptual experience of haptic-induced urgency is well studied with self-reporting and behavioral evidence, this is the first effort to evaluate the neural correlates to haptic-induced urgency using EEG. Further research is warranted to identify unique correlates to the cognitive processes associated with urgency from sensory feedback correlates.

Insight into the Imbibition Behavior of Low-Frequency Artificial Vibration Stimulation in Tight Sandstone.

Spontaneous imbibition is the primary mechanism responsible for the enhanced oil production in a tight reservoir after hydraulic fracturing. In this article, a low-frequency artificial vibration physics stimulation method was employed to evaluate the effect of low-frequency vibration on imbibition recovery in tight sandstones. Furthermore, a high-precision in situ computed tomography (CT) scan was employed to investigate the effect of low-frequency vibration on the distribution of remaining oil micro-occurrence dynamic alterations in pore space. The findings of the study show that (1) low-frequency artificial physical vibration stimulation has been found to be highly effective in enhancing imbibition recovery in tight sandstone. The sensitivity of the vibration parameters on imbibition recovery from highest to lowest is vibration frequency, vibration intensity, and vibration time. The optimum vibration parameters for this process are a vibration frequency of 30 Hz, a vibration intensity of 2.0 m/s2, and a vibration time of 30 h. (2) Under the optimum low-frequency vibration, the imbibition recovery of tight sandstone with various physical properties can reach between 13.6 and 28.3%. This is remarkably higher than the spontaneous imbibition recovery, which ranges from 9.4 to 17.1%. Additionally, core samples with higher permeability and better pore structure show a more significant increase in imbibition recovery under the vibration treatment. Furthermore, low-frequency vibration stimulation effectively shortens the imbibition completion time, reducing the completion time from 81 h to approximately 55 h. (3) After the spontaneous imbibition process, the initial continuous oil phase present in the pore space is dispersed by the water phase imbibition process. The remaining oil is dominant in the form of a network type, which is concentrated in the central pore space area of the core. Low-frequency vibration treatment can effectively promote a positive imbibition process. The network remaining oil saturation in the core can be further dispersed, especially closer to the surface of the core area after frequency vibration treatment. Then, the cluster remaining oil type with a more dispersed and simpler individual structure has become the new dominant remaining oil micro-occurrence form in the pore space. The findings of this research investigate a novel technological approach to enhance the imbibition efficiency of a tight sandstone reservoir.

The gingival crevicular fluid biomarkers with micropulse vibration device: A pilot study

PurposeThe aim of this study is to investigate the impact of vibration stimulation on gingival crevicular fluid biomarkers and orthodontic tooth movement. MethodsForty patients were randomly assigned to receive therapy with an intraoral vibration device (n = 20, AcceleDent®) or no treatment (n = 20) at a university orthodontic clinic. The quantity of fluid in the gingival sulcus, biomarkers of each fluid in the gingival sulcus, and orthodontic tooth movement were analyzed at three-time intervals (T1, T2, T3) before and after therapy (T0). ResultsThe results showed that vibration treatment led to higher levels of osteoclast biomarkers (RNAKL, RANKL/OPG) and inflammatory biomarkers (TNF-, IL-11, IL-18) compared to the control group. Additionally, vibration treatment at T1, T2, and T3 significantly improved tooth mobility and GCF volume. The gingival crevicular fluid biomarker levels of the T0, T1, and T2 vibration groups, as well as IL-11, IL-18, TGF-1, and TNF-α vibration groups, were significantly higher than those of the control group at different time points. Conclusionvibration therapy was found to be closely associated with bone-breaking cells and inflammatory factor levels.

Analysis and NDT applications of a gas discharge electroacoustic transducer

In this study, a gas discharge electroacoustic transducer (GDEAT) based on a pulsed electric discharge in the air under atmospheric pressure has been investigated. By evaluating acoustic pressure and recording amplitude-frequency characteristics of membranes, the acoustic characteristic of GDEATs have been obtained in the frequency range from 40 Hz to 4 MHz. The electro-thermo-acoustic processes have been studied in gas discharge systems of an open type where the electrode space is in a direct contact with the ambient. Some features of using the above-mentioned GDEATs in nondestructive testing (NDT) of materials have been demonstrated. It has been shown that, on one hand, the wear of both electrodes and insulation limits a work life of a transducer electrode system, but, from the other hand, this may lead to deposition of micro-particles on the surface of an object under test. The wear of electrode systems was evaluated quantitatively, and the results of the chemical analysis of deposited micro-particles have been presented. The use of a GDEATs for non-contact stimulation of local resonant vibrations in subsurface defects and visualizing vibrations by means of laser dopler vibrometry has been shown in the case of NDT of a glass fiber composite.

Effects of postural control by personal mobility on human joint movements-prototype of a new alert system for personal mobility devices

Purpose: This study aimed to develop a prototype Personal Mobility (PM) system with human-robot synchronous motion measurement and sensory feedback as an attention reminder to ensure the safe performance of sustained, step-by-step rehabilitation tailored to the daily living conditions of elderly individuals. Methods: Five healthy adults were fitted with a simulation tool to experience the elderly, and inertial measurement unit sensors were placed on the subjects and the PM device to measure joint movements during two postural movements (sitting to supine and supine to standing). In addition, vibration stimulation and voice guidance were implemented as alerts at a certain set threshold of the joint motion angle. We analyzed the deviation of each joint motion between the subject and the PM device regarding the angle measurements of the trunk, hip, knee, and ankle joints. Results: Trunk angle misalignment was high in the sitting-to-supine position. Hip angle misalignment was greater in the supine to standing position. As an alert system, vibration and voice guidance could be presented to the subject with a 0.3-second delay after the set threshold was reached. Conclusion: The misalignment between a human and a motorized wheelchair in contact with the human is more than several tens of degrees when expressed as the angle change value of the joint motion. We believe that a system that can constantly sense and alert the user regarding whether the user and the PM device are in sync is necessary for PM devices being used in rehabilitation or as daily life support.