Force Exertion Research Articles

Haptic Feedback and Force-Based Teleoperation in Surgical Robotics

This article presents an overview of the current state of research and application of haptic (primarily kinesthetic) feedback and force-based teleoperation in the context of surgical robotics. Telerobotic surgery provides an approach for transferring the sensorimotor skills of a surgeon through a robotic platform to perform surgical intervention inside a patient’s body. Integration of advanced sensing and haptic technologies in telerobotic surgery can help to enhance the sensory awareness and motor accuracy of the surgeon, thereby leading to improved surgical procedures and outcomes for patients. The primary mode of sensory feedback has been through 3-D visual observation using stereo endoscopes. However, until recently, the sense of touch, i.e., haptics, has been missing in the commercial telesurgery robots approved for use in the operating room despite over two decades of research and development in the field of haptics for teleoperated systems (“telehaptics”). Research has shown that high-fidelity force feedback can enhance the performance of telesurgery and potential outcomes by enabling the surgeon to have a more natural feel of interaction between surgical tools and tissue as normally experienced during open surgery. Interaction forces, such as those generated during palpation of tissue, insertion of a needle, unintentional (and potentially unsafe) exertion of force by a tool, suture breakage, needle slippage, or tool interaction, are replaced by indirect (virtual) sensations, termed visual haptics, which provides an alternative to sensory compensation. Although there is a significant amount of literature supporting this benefit, there are still several important technical challenges in introducing haptics in telesurgery, including instrumentation, fidelity (transparency), stability, and modalities for force reflection, e.g., direct or indirect. This article examines these challenges and discusses recent work on haptics-based teleoperated surgical robotic systems.

Sensorimotor Cortex GABA Moderates the Relationship between Physical Exertion and Assessments of Effort.

Experiences of physical exertion guide our assessments of effort. While these assessments critically influence our decisions to engage in daily activities, little is known about how they are generated. We had female and male human participants exert grip force and assess how effortful these exertions felt; and used magnetic resonance spectroscopy to measure their brain GABA concentration. We found that variability in exertion (i.e., the coefficient of variation in their force exertion profile) was associated with increases in assessments of effort, making participants judge efforts as more costly. GABA levels in the sensorimotor cortex (SM1) moderated the influence of exertion variability on overassessments of effort. In individuals with higher sensorimotor GABA, exertion variability had a diminished influence on overassessments of effort. Essentially, sensorimotor GABA had a protective effect on the influence of exertion variability on inflations of effort assessment. Our findings provide a neurobiological account of how the brain's GABAergic system integrates features of physical exertion into judgments of effort, and how basic sensorimotor properties may influence higher-order judgments of effort.SIGNIFICANCE STATEMENT Feelings of effort critically shape our decisions to partake in activities of daily living. It remains unclear how the brain translates physical activity into judgments about effort (i.e., "How effortful did that activity feel?"). Using modeling of behavior and neuroimaging, we show how the nervous system uses information about physical exertion to generate assessments of effort. We found that higher variability in exertion was associated with increases in assessments of effort, making participants judge efforts as more costly. GABA, the brain's main inhibitory neurotransmitter, moderated the influence of exertion variability on overassessments of effort. These findings illustrate how low-level features of motor performance and sensorimotor neurochemistry influence higher-order cognitive processes related to feelings of effort.

Ergonomics and musculoskeletal disorders among health care professionals: Prevention is better than cure.

Medical profession is demanding and requires long working hours, lengthy procedures, and constant posturing. Musculoskeletal disorders are common among health care professionals (HCP). The commonest musculoskeletal disorders reported include pain in the neck, back, shoulders, elbows, wrists, repetitive strain disorders, nerve injuries and chronic pain disorders. It can result in reduced performance, poor quality of life and significant disability. Ergonomics is the science of adapting the job, equipment, and the humans to each other for optimal safety and productivity. If workplace of a HCP is ergonomically inadequate it will lead to musculoskeletal disorders. The main ergonomic issues include sustained postures, repetitive tasks, forceful hand exertions, use of equipment and precision requirement. In order to prevent ergonomic related injuries, there is a need to increase awareness among HCPs regarding physical fitness, correct posturing, ergonomic adjustments in equipment and environment, and early recognition of problems specific to field.

Providing physical relief for nurses by collaborative robotics

Manual patient handling is one of the most significant challenges leading to musculoskeletal burden among healthcare workers. Traditional working techniques could be enhanced by innovations that can be individually adapted to the physical capacity of nurses. We evaluated the use of a robotic system providing physical relief by collaboratively assisting nurses in manual patient handling tasks. By quantifying kinetic and muscle activity data, it was possible to distinguish two kinds of movement patterns. Highly asymmetric postures and movements corresponded to distinct extremes in lower limb and spine muscle activity data. The use of collaborative robotics significantly reduced maximum force exertion in the caregiving process by up to 51%. Lateral flexion and torsion of the trunk were reduced by up to 54% and 87%, respectively, leading to a significant reduction in mean spine muscle activity of up to 55%. These findings indicate the feasibility of collaborative robot-assisted patient handling and emphasize the need for future individual intervention programs to prevent physical burden in care.

3D printed auxetic heel pads for patients with diabetic mellitus

More than 422 million people worldwide suffered from diabetes mellitus (DM) in 2021. Diabetic foot is one the most critical complications resultant of DM. Foot ulceration and infection are frequently arisen, which are associated with changes in the mechanical properties of the plantar soft tissues, peripheral arterial disease, and sensory neuropathy. Diabetic insoles are currently the mainstay in reducing the risk of foot ulcers by reducing the magnitude of the pressure on the plantar Here, we propose a novel pressure relieving heel pad based on a circular auxetic re-entrant honeycomb structure by using three-dimensional (3D) printing technology to minimize the pressure on the heel, thus reducing the occurrence of foot ulcers. Finite element models (FEMs) are developed to evaluate the structural changes of the developed circular auxetic structure upon exertion of compressive forces. Moreover, the effects of the internal angle of the re-entrant structure on the peak contact force and the mean pressure acting on the heel as well as the contact area between the heel and the pads are investigated through a finite element analysis (FEA). Based on the result from the validated FEMs, the proposed heel pad with an auxetic structure demonstrates a distinct reduction in the peak contact force (∼10%) and the mean pressure (∼14%) in comparison to a conventional diabetic insole (PU foam). The characterized result of the designed circular auxetic structure not only provides new insights into diabetic foot protection, but also the design and development of various impact resistance products.

Characterization of Musculoskeletal Injury Risk in Dungeness Crab Fishing

ABSTRACT Objectives: Commercial Dungeness crab fishermen’s manual crab pot handling activities can be done in harsh outdoor working environments at sea and can pose well-known physical risk factors associated with musculoskeletal injury including forceful exertion, repetition and awkward posture. The nonfatal injury rate in this fishing fleet is 3.4 per 1,000 full-time equivalent workers. Two-thirds of self-reported injuries in the fleet were musculoskeletal sprains and strains. To date, no objective biomechanical assessment of musculoskeletal disorder (MSD) risk has been conducted due to the challenging work environment. Methods: The aim of this study was to determine the feasibility of collecting objective biomechanical assessments (i.e., posture and repetition) using inertial measurement unit (IMU) sensors placed on the arms and torso of professional deckhands (n = 7) while at sea, harvesting Dungeness crab. Based on the IMU-measured posture data, fishermen’s anthropometry, and crab pot weights, biomechanical loading of the low back and both shoulders was estimated. Results: The IMU sensor data showed that commercial Dungeness crab fishing is highly repetitive and poses awkward postures in the shoulders and back. The estimated static low back compression, shear force, and flexion moment about the shoulders and low back (L5/S1) indicate potential injury risk associated with harvesting crab. Conclusion: The results indicate that objective biomechanical assessment using the IMU sensors is feasible in the commercial fishing environment.

MP32-08 DEVELOPMENT OF A SAFE ALTERNATIVE TO FOLEY CATHETER (SAFECATH) TO REDUCE CATHETER-INDUCED TRAUMA

You have accessJournal of UrologyCME1 May 2022MP32-08 DEVELOPMENT OF A SAFE ALTERNATIVE TO FOLEY CATHETER (SAFECATH) TO REDUCE CATHETER-INDUCED TRAUMA Hersh Bendre, Graham Lieberman, Jonathan Kusner, Amy Hao, and Francis McGovern Hersh BendreHersh Bendre More articles by this author , Graham LiebermanGraham Lieberman More articles by this author , Jonathan KusnerJonathan Kusner More articles by this author , Amy HaoAmy Hao More articles by this author , and Francis McGovernFrancis McGovern More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002581.08AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The design of the foley catheter inherently leads to catheter-induced trauma (CIT), which occurs in 1-2% of catheterized patients and results in 200,000 injuries per year. Most major Injuries occur due to intraurethral inflation of the balloon (type 2) or traumatic removal of the inflated balloon (type 3). These lead to increased acute care needs, chronic urethral stricture disease, and increased costs of several billion dollars per year. We describe the development of a novel urinary catheter balloon design which reduces types 2 and 3 CIT. METHODS: We used Systematic Innovative Thinking techniques to develop a urinary catheter design which met the following conditions: 1) Unable to dilate/disrupt the urethra during intraurethral activation, 2) Able to remain internalized when exposed to non-traumatic extraction forces, 3) Able to be removed atraumatically when exposed to extraction forces that induce trauma with a foley catheter. This design was prototyped and tested using ex-vivo porcine bladders. RESULTS: Our design consists of a set of non-radially expanding balloons near the tip of the catheter that lay offset from the longitudinal axis. On inflation, the offset position of the balloons causes differential lengthening of one side of the catheter, resulting in a curling of the catheter tip without radial expansion. Testing demonstrated a maximal diameter of 25 Fr compared to 80 Fr for a standard 10cc foley catheter balloon. SafeCath exerted less than 5 N of sheer force. Mean extraction forces from porcine bladders for the SafeCath and foley catheter were 10.6 N and 27.7 N respectively. Foley catheter extraction resulted in gross urethral disruption, while no trauma was seen with SafeCath. CONCLUSIONS: We designed and tested a urinary catheter with a novel internalization mechanism that reduces the trauma caused by the spherical internalization balloon of foley catheters. Testing demonstrated that SafeCath has a smaller maximal diameter and low sheer force exertion, prohibiting injury with intraurethral inflation. In addition, the SafeCath remains internalized up to a safe threshold extraction force, after which it is atraumatically removed. This preliminary data suggests SafeCath shows promise as a urinary catheter which is able to reduce or eliminate types 2 and 3 CIT. Source of Funding: None © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e534 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Hersh Bendre More articles by this author Graham Lieberman More articles by this author Jonathan Kusner More articles by this author Amy Hao More articles by this author Francis McGovern More articles by this author Expand All Advertisement PDF DownloadLoading ...

Risk Factors Associated with Lower Back Pain among Nurses: A Case of National Rehabilitation Centre in Ruwa, Zimbabwe

Health care providers are exposed to a myriad of occupation safety and health hazards both in the private and public sector. Nurses and other health professional are exposed to awkward postures, repetitive movements, force exertion and manual handling for prolonged periods. Low back pain (LBP) is a public health problem worldwide and is a common cause of work-related disorder among workers, especially in the nursing profession. The objectives of the study were to ascertain the prevalence of lower back pain among nurses at National Rehabilitation Centre and identify and assess risk factors associated with back pain among nurses at National Rehabilitation Centre. The research was carried out using a cross sectional study design. A total of 100 nurses were randomly selected. A Modified Nordic Musculoskeletal Questionnaire (NMQ) was used to assess prevalence, interference and physician visits by nurses. A predesigned questionnaire was used to assess risk factors. Descriptive statistics and Pearson's Chi-square tests were used to analyse data. All data was analysed using SPPS version 25. Results show that the age of nurses ranged between 26 and 64 years (42±9.2) and majority of them (64%) were married. Very few nurses (6%) were male which means that the rehabilitation nursing field is female dominated. The highest reported pain was in the lower back in the past 12 months which was 72% with 12% in the past 7 days. This was followed by upper back which recorded 32% in the past year and 13% in the past week. Age and having chronic conditions were significantly associated with lower back pain among nurses with p = values of 0.031 and 0.020 respectively. Results also indicate that there was a significant association between lower back pain with environmental factors (χ2 = 9, p = 0.014), job-related factors (χ2 = 26, p = 0.000) and physical factors (χ2 = 18, p = 0.020). In conclusion, there is high prevalence of lower back pain among nurses. Lower back pain was associated with age, environmental factors and job-related factors. There is need for training, exercises, and assessment of individual capacities to prevent lower back pain among rehabilitation nurses.

Association between knee extensor force steadiness and postural stability against mechanical perturbation in patients with Parkinson’s disease

ObjectiveLower extremity force steadiness has been shown to decrease with aging and neuromotor dysfunction and to be associated with physical function and fall. Although patients with Parkinson’s disease (PD) experience decreased force steadiness, whether the extent of force steadiness differs according to target force or whether this steadiness is associated with postural control remain unclear. Therefore, this study aimed to compare the force steadiness while steadily exerting low and moderate levels of knee extensor force between individuals with and without PD and to examine the association between force steadiness and postural instability against mechanical perturbation in PD. MethodsA total of 33 patients with PD (mean age, 71.7 years) and 33 healthy controls (72.2 years) participated in this study. Participants with PD were classified into postural stability or instability groups based on the Movement Disorder Society-sponsored revision of the Unified Parkinson’s Disease Rating Scale motor exam item 12. Participants performed steady task of the knee isometric extension at two levels (10% and 50% of maximal voluntary contraction [MVC]). ResultsForce steadiness at 10% MVC was lower in postural instability group than that in the control and postural stability groups (P < 0.05) after adjusting for age, sex, and body mass index, whereas it was not significantly different at 50% MVC among the three groups. DiscussionThese results suggest that the knee extensor force steadiness is affected in patients with PD having postural instability against mechanical perturbation during low intensity force exertion and is not affected regardless of the presence of postural instability during moderate intensity force exertion.

Cytotoxic T Lymphocyte Activation Signals Modulate Cytoskeletal Dynamics and Mechanical Force Generation.

Cytotoxic T lymphocytes (CTLs) play an integral role in the adaptive immune response by killing infected cells. Antigen presenting cells (APCs), such as dendritic cells, present pathogenic peptides to the T cell receptor on the CTL surface and co-stimulatory signals required for complete activation. Activated CTLs secrete lytic granules containing enzymes that trigger target cell death at the CTL-target contact, also known as the immune synapse (IS). The actin and microtubule cytoskeletons are instrumental in the killing of CTL targets. Lytic granules are transported along microtubules to the IS, where granule secretion is facilitated by actin depletion and recovery. Furthermore, actomyosin contractility promotes target cell death by mediating mechanical force exertion at the IS. Recent studies have shown that inflammatory cytokines produced by APCs, such as interleukin-12 (IL-12), act as a third signal for CTL activation and enhance CTL proliferation and effector function. However, the biophysical mechanisms mediating such enhanced effector function remain unclear. We hypothesized that the third signal for CTL activation, IL-12, modulates cytoskeletal dynamics and force exertion at the IS, thus potentiating CTL effector function. Here, we used live cell total internal reflection fluorescence (TIRF) microscopy to study actomyosin and microtubule dynamics at the IS of murine primary CTLs activated in the presence of peptide-MHC and co-stimulation alone (two signals), or additionally with IL-12 (three signals). We found that three signal-activated CTLs have altered actin flows, myosin dynamics and microtubule growth rates as compared to two signal-activated CTLs. We further showed that lytic granules in three-signal activated CTLs are less clustered and have lower velocities than in two-signal activated CTLs. Finally, we used traction force microscopy to show that three signal-activated CTLs exert greater traction forces than two signal-activated CTLs. Our results demonstrate that activation of CTLs in the presence of IL-12 leads to differential modulation of the cytoskeleton, thereby augmenting the mechanical response of CTLs to their targets. This indicates a potential physical mechanism via which the third signal can enhance the CTL response.

The Prevalence, Causes and Prevention of Occupational Musculoskeletal Disorders

Musculoskeletal disorders (MSDs) are collectively referring to an array of conditions affecting the human locomotor system, such as muscles, nerves, joints, tendons and spinal discs. MSDs related to work are called occupational MSDs and are typically caused by physical factors consisting of repetitive tasks, forceful exertions, awkward positions, vibration due to use of vibrational tools and prolonged staying in the same positions. These physical factors are often complicated by psychosocial factors comprising job demand, job control, social support, job satisfaction, job security, work arrangement, etc. which can aggravate the biomechanical loading imposed by physical factors, thus resulting in more severe outcomes. Besides, individual factors such as health conditions, age, education level and medical history could lead to highly variable physiological responses and internal tolerances, hence outcomes. As the physical and psychosocial risk factors vary widely in different workplaces, the prevalence of MSDs tends to vary with sectors, occupations and even regions. Generally, healthcare sector has been reported to have relatively high occupational MSDs cases in multiple nations. To prevent occupational MSDs, priority should be given to elimination of the associated risks through job and workplace designs and management. Where elimination is not practical, the risks could be reduced through modification of workplace layout, work environment, work systems and tools as well as the use of mechanical aids. Provision of information, instruction and training, and other administrative controls such as job rotation which do not target at reducing the risks would have lower priority and should be used together with other control measures of higher priority.

A passive admittance controller to enforce Remote Center of Motion and Tool Spatial constraints with application in hands-on surgical procedures

The restriction of feasible motions of a manipulator link constrained to move through an entry port is a common problem in minimally invasive surgery procedures. Additional spatial restrictions are required to ensure the safety of sensitive regions from unintentional damage. In this work, we design a target admittance model that is proved to enforce robot tool manipulation by a human through a remote center of motion and to guarantee that the tool will never enter or touch forbidden regions. The control scheme is proved passive under the exertion of a human force ensuring manipulation stability, and smooth natural motion in hands-on surgical procedures enhancing the user’s feeling of control over the task. Its performance is demonstrated by experiments with a setup mimicking a hands-on surgical procedure comprising a KUKA LWR4+ and a virtual intraoperative environment.

The sensitivity of shoulder muscle fatigue to vertical hand location during complex manual force exertions

Occupational shoulder overexposures, including increased muscle activity and associated localized muscle fatigue, typically scale with manual exertion height during static or intermittent overhead work. It is unknown how this response is affected during complex (i.e. multi-directional and varying magnitude) manual force exertions, and how this work profile may attenuate task endurance. The purpose of this study was to evaluate the influence of manual exertion height on shoulder muscle fatigue responses during a multi-directional manual exertion protocol. Fourteen participants completed a shoulder fatiguing protocol by exerting manual forces (push up, down, left, and right) at three vertical hand location heights (low, shoulder and overhead). Decline in strength, myoelectric indicators of fatigue, ratings of perceived discomfort and endurance time were used to track the progression of fatigue at the different height conditions, and differential effects due to direction of exertion were also examined. The overhead and shoulder height conditions resulted in significantly increased muscle activation, discomfort and strength decline in comparison to the low condition. Fatigue responses between overhead and shoulder level work were generally similar, as no differences existed in endurance time, RPD and mean power frequency for these conditions, but the overhead condition resulted in a substantial 18% reduction in downwards strength. The downwards exertions seemed to elicit the greatest fatigue response, despite the upwards direction requiring the highest global muscle activity. These results add evidence that repetitive overhead work should be avoided when possible, but provides novel insight on how direction of force application can be further considered in design recommendations.

A Countermovement Jump for the Midterm Assessment of Force and Power Exertion After Anterior Cruciate Ligament Reconstruction.

The aim of this study was to assess force and power exertion during a countermovement jump after anterior cruciate ligament reconstruction using either semitendinosus and gracilis or bone-patellar tendon-bone graft. One hundred-nineteen semitendinosus and gracilis and 146 bone-patellar tendon-bone participants performed a countermovement jump on two force platforms after 3 (T1) and 6-9 mos (T2) from surgery. Twenty-four healthy participants served as control group. Peak force of eccentric and concentric phases and peak power were obtained from the analysis of vertical components of the ground reaction forces. Asymmetry was quantified by means of limb symmetry index. Eccentric peak force was significantly ( P < 0.05) lower than concentric peak force in both bone-patellar tendon-bone and semitendinosus and gracilis at T1 and T2. At T1, bone-patellar tendon-bone showed higher peak power, but lower limb symmetry index in eccentric and concentric compared with semitendinosus and gracilis. At T2, bone-patellar tendon-bone showed higher peak power than semitendinosus and gracilis, although there were no differences in limb symmetry index between the two groups, which however was significantly ( P < 0.05) lower in both groups when compared with control group. Bone-patellar tendon-bone and semitendinosus and gracilis participants showed asymmetries in eccentric and concentric force during a countermovement jump. Bone-patellar tendon-bone showed greater asymmetries and a higher peak power respect to semitendinosus and gracilis participants.

Modeling and Validation of Fatigue and Recovery of Muscles for Manual Demolition Tasks.

Manual demolition tasks are heavy, physically demanding tasks that could cause muscle fatigue accumulation and lead to work-related musculoskeletal disorders (WMSDs). Fatigue and recovery models of muscles are essential in understanding the accumulation and the reduction in muscle fatigue for forceful exertion tasks. This study aims to explore the onset of muscle fatigue under different work/rest arrangements during manual demolition tasks and the offset of fatigue over time after the tasks were performed. An experiment, including a muscle fatigue test and a muscle fatigue recovery test, was performed. Seventeen male adults without experience in demolition hammer operation were recruited as human participants. Two demolition hammers (large and small) were adopted. The push force was either 20 or 40 N. The posture mimicked that of a demolition task on a wall. In the muscle fatigue test, the muscle strength (MS) before and after the demolition task, maximum endurance time (MET), and the Borg category-ratio-10 (CR-10) ratings of perceived exertion after the demolition task were measured. In the muscle fatigue recovery test, MS and CR-10 at times 1, 2, 3, 4, 5, and 6 min were recorded. Statistical analyses were performed to explore the influence of push force and the weight of the tool on MS, MET, and CR-10. Both muscle fatigue models and muscle fatigue recovery models were established and validated. The results showed that push force affected MET significantly (p < 0.05). The weight of the tool was significant (p < 0.05) only on the CR-10 rating after the first pull. During the muscle fatigue recovery test, the MS increase and the CR-10 decrease were both significant (p < 0.05) after one or more breaks. Models of MET and MS prediction were established to assess muscle fatigue recovery, respectively. The absolute (AD) and relative (RD) deviations of the MET model were 1.83 (±1.94) min and 34.80 (±31.48)%, respectively. The AD and RD of the MS model were 1.39 (±0.81) N and 1.9 (±1.2)%, respectively. These models are capable of predicting the progress and recovery of muscle fatigue, respectively, and may be adopted in work/rest arrangements for novice workers performing demolition tasks.

Large-scale physical modeling of broken solitary waves impacting elevated coastal structures

ABSTRACT Amongst extreme hydrodynamic events are bore- and surge-type flow motions that are observed in the context of storm surges induced by tropical cyclones, but also occur when tsunami or flash floods strike. Coastal houses built on elevated pile foundations have suffered less damages in recent extreme hydrodynamic events since the water could pass beneath the floor slabs decreasing the exertion of forces onto structures. To date, research pertaining to horizontal and vertical forces on elevated structures is still scarce. Specifically, previous research may not be applicable to cases of bore-type inundation interacting with elevated coastal structures. This work hence aims to model non-elevated and elevated coastal structure, and to deepen insight into forces with a focus on the structural elevation. For this purpose, large-scale experimental tests were performed on a uniform 1:15 slope in combination with an adjacent horizontal plane. Idealized residential buildings on a length scale of 1:5 were designed to simulate loading conditions of broken solitary waves on slab-on-grade and elevated buildings. A wide range of horizontal forces between 0.1 and 10 , vertical forces between 0.5 and 7.5 and overturning moments up to 4.5 were measured. In accordance with the experimental results, design equations were derived.

定期的な有酸素性運動および筋力発揮調整能の課題を併用したトレーニングが筋力発揮調整能に及ぼす影響

定期的な有酸素性運動および筋力発揮調整能の課題を併用したトレーニングが筋力発揮調整能に及ぼす影響

A Directional Vibrotactile Feedback Interface for Ergonomic Postural Adjustment.

The objective of this paper is to develop and evaluate a directional vibrotactile feedback interface as a guidance tool for postural adjustments during work. In contrast to the existing active and wearable systems such as exoskeletons, we aim to create a lightweight and intuitive interface, capable of guiding its wearers towards more ergonomic and healthy working conditions. To achieve this, a vibrotactile device called ErgoTac is employed to develop three different feedback modalities that are able to provide a directional guidance at the body segments towards a desired pose. In addition, an evaluation is made to find the most suitable, comfortable, and intuitive feedback modality for the user. Therefore, these modalities are first compared experimentally on fifteen subjects wearing eight ErgoTac devices to achieve targeted arm and torso configurations. The most effective directional feedback modality is then evaluated on five subjects in a set of experiments in which an ergonomic optimisation module provides the optimised body posture while performing heavy lifting or forceful exertion tasks. The results yield strong evidence on the usefulness and the intuitiveness of one of the developed modalities in providing guidance towards ergonomic working conditions, by minimising the effect of an external load on body joints. We believe that the integration of such low-cost devices in workplaces can help address the well-known and complex problem of work-related musculoskeletal disorders.

Towards Soft Wearable Strain Sensors for Muscle Activity Monitoring

The force-generating capacity of skeletal muscle is an important metric in the evaluation and diagnosis of musculoskeletal health. Measuring changes in muscle force exertion is essential for tracking the progress of athletes during training, for evaluating patients’ recovery after muscle injury, and also for assisting the diagnosis of conditions such as muscular dystrophy, multiple sclerosis, or Parkinson’s disease. Traditional hardware for strength evaluation requires technical training for operation, generates discrete time points for muscle assessment, and is implemented in controlled settings. The ability to continuously monitor muscle force without restricting the range of motion or adapting the exercise protocol to suit specific hardware would allow for a richer dataset that can help unlock critical features of muscle health and strength evaluation. In this paper, we employ wearable, ultra-sensitive soft strain sensors for tracking changes in muscle deformation during contractions. We demonstrate the sensors’ sensitivity to isometric contractions, as well as the sensors’ capacity to track changes in peak torque over the course of an isokinetic fatiguing protocol for the knee extensors. The wearable soft system was able to efficiently estimate peak joint torque reduction caused by muscle fatigue (mean NRMSE = 0.15±0.03).

Development and Usability Testing of a Finger Grip Enhancer for the Elderly

As people age, their finger function deteriorates due to muscle, nerve, and brain degeneration. While exercises might delay this deterioration, an invention that enhances elderly people’s pinching abilities is essential. This study aims to design and develop a finger grip enhancer that facilitates the day-to-day pinching activities of elderly people. This research is an extension of a previous study that conceptualised a finger grip enhancer. The device facilitates finger flexion on the thumb and index finger, and weighs 520 g, allowing for improved portability and sufficient force exertion (13.9 N) for day-to-day pinching. To test for usability, eleven subjects aged 65 years and above performed a pinch-lift-hold test on various household objects. The pinch force before and after utilising the device was measured. Using Minitab 18, the statistical significance of using this device was analysed with a paired-samples t-test. With this device, the elderly people’s pinching abilities significantly improved in both pinch force and pinch force steadiness (p &lt; 0.05). The proposed device has the potential to enhance elderly people’s quality of life by supporting a firm pinch in the handling of everyday objects. This research has applicational value in developing exoskeleton devices for patients who require rehabilitation.