The effects of chlorination, thickness, and moisture on glove donning efficiency.

Changing gloves more frequently is encouraged, more now than ever given the COVID-19 pandemic. When the donning process has moisture introduced, however, complications can arise, which consumes vital time. Most commonly, gloves undergo a chlorination treatment to reduce glove tack, allowing easier donning. To assess the effects of different chlorination strengths and glove thicknesses on donning, acrylonitrile butadiene gloves were manufactured at two different thicknesses (0.05 and 0.10 mm) with 4 different chlorination treatments: 0, 500, 1000 and 2000 ppm. Six participants were used to assess the time taken to don each of the glove sets with dry and wet hands (16 tests in total). Overall, the thicker gloves took longer to don, due to differences in the material stiffness hindering the donning process. The quickest performance from the chlorinated gloves was noted in the 1000 and 2000 ppm concentrations. Wet conditions also showed significant increases in the donning time.Practitioners Summary: The study was conducted based on the gaps identified in previous literature reviews which revealed the requirement for a greater understanding of glove donning process. It was found a stronger chlorination was detrimental when the hands were wet, but better when dry. Thicker gloves were also found to be detrimental. Abbreviations: PPE: personal protective equipment; NBR: acrylonitrile butadiene rubber; NRL: natural rubber latex; EN: European standards; s: seconds; Ts: tensile strength; Fb: force at break; T: thickness; Eb: elongation at break; HSD: honest significant difference; FTIR: Fourier transform infrared; covid-19: coronavirus disease 2019.

Boot-insole effects on comfort and plantar loading at the heel and fifth metatarsal during running and turning in soccer.

Plantar loading may influence comfort, performance and injury risk in soccer boots. This study investigated the effect of cleat configuration and insole cushioning levels on perception of comfort and in-shoe plantar pressures at the heel and fifth metatarsal head region. Nine soccer academy players (age 15.7 ± 1.6 years; height 1.80 ± 0.40 m; body mass 71.9 ± 6.1 kg) took part in the study. Two boot models (8 and 6 cleats) and two insoles (Poron and Poron/gel) provided four footwear combinations assessed using pressure insoles during running and 180° turning. Mechanical and comfort perception tests differentiated boot and insole conditions. During biomechanical testing, the Poron insole generally provided lower peak pressures than the Poron/gel insole, particularly during the braking step of the turn. The boot model did not independently influence peak pressures at the fifth metatarsal, and had minimal influence on heel loads. Specific boot-insole combinations performed differently (P < 0.05). The 8-cleat boot and the Poron insole performed best biomechanically and perceptually, but the combined condition did not. Inclusion of kinematic data and improved control of the turning technique are recommended to strengthen future research. The mechanical, perception and biomechanical results highlight the need for a multi-faceted approach in the assessment of footwear.

The influence of tennis court surfaces on player perceptions and biomechanical response.

This study aimed to examine player perceptions and biomechanical responses to tennis surfaces and to evaluate the influence of prior clay court experience. Two groups with different clay experiences (experience group, n = 5 and low-experience group, n = 5) performed a 180° turning movement. Three-dimensional ankle and knee movements (50 Hz), plantar pressure of the turning step (100 Hz) and perception data (visual analogue scale questionnaire) were collected for two tennis courts (acrylic and clay). Greater initial knee flexion (acrylic 20. 8 ± 11.2° and clay 32.5 ± 9.4°) and a more upright position were reported on the clay compared to the acrylic court (P < 0.05). This suggests adaptations to increase player stability on clay. Greater hallux pressures and lower midfoot pressures were observed on the clay court, allowing for sliding whilst providing grip at the forefoot. Players with prior clay court experience exhibited later peak knee flexion compared to those with low experience. All participants perceived the differences in surface properties between courts and thus responded appropriately to these differences. The level of previous clay court experience did not influence players' perceptions of the surfaces; however, those with greater clay court experience may reduce injury risk as a result of reduced loading through later peak knee flexion.

A critical review of glove and hand research with regard to medical glove design.

Research from a number of areas was surveyed, including hand function; skin friction; manual performance testing; glove comfort, fit and durability; and user perception. The relevance of the research to medical glove design was discussed. It was concluded that, while an understanding has been gained of the factors that affect glove performance in general, specific application to thin rubber gloves has not been well explored. The focus in glove performance testing has also been on simple tasks such as pegboards, which do not necessarily assess the fine dexterity required in many surgical tasks. Recommendations were made for the development of a new battery of tests specific to medical gloves that would simulate real medical tasks and could produce repeatable results and have sufficient resolution to differentiate between glove types.

A finite element model for predicting impact-induced damage to a skin simulant.

A finite element model was developed for assessing the efficacy of rugby body padding in reducing the risk of sustaining cuts and abrasions. The model was developed to predict the onset of damage to a soft tissue simulant from concentrated impact loading (i.e., stud impact) and compared against a corresponding experiment. The damage modelling techniques involved defining an element deletion criterion, whereby those on the surface of the surrogate were deleted if their maximum principal stress reached a predefined value. Candidate maximum principal stress values for element deletion criteria were identified independently from puncture test simulations on the soft tissue simulant. Experimental impacts with a stud were carried out at three energies (2, 4 and 6 J), at three angular orientations (0°, 15° and 30°) and compared to corresponding simulations. Suitable maximum principal stress values for element deletion criteria settings were first identified for the 4 J impact, selecting the candidates that best matched the experimental results. The same element deletion settings were then applied in simulations at 2 and 6 J and the validity of the model was further assessed (difference < 15% for the force at tear and < 30% for time to tear). The damage modelling techniques presented here could be applied to other skin simulants to assess the onset of skin injuries and the ability of padding to prevent them.

Assessing friction and damage of cell monolayers on soft substrates in vitro.

In the area of surgical applications, understanding the interaction between medical device materials and tissue is important since this interaction may cause complications. The interaction often consists of a cell monolayer touching the medical device that can be mimicked in vitro. Prominent examples of this are contact lenses, where epithelial cells interact with the contact lens, or stents and catheters, which are in contact with endothelial cells. To investigate those interactions, in previous studies, expensive microtribometers were used to avoid pressures in the contact area far beyond physiologically relevant levels. Here, we aim to present a new methodology that is cost- and time-efficient, more accessible than those used previously and allows for the application of more realistic pressures, while permitting a quantification of the damage caused to the monolayer. For this, a soft polydimethylsiloxane is employed that better mimics the mechanical properties of blood vessels than materials used in other studies. Furthermore, a technique to account for misalignments within the experiment set-up is presented. This is carried out using the raw spatial and force data recorded by the tribometer and adjusting for misalignments. The methodology is demonstrated using an endothelial cell (human umbilical vein endothelial cells) monolayer.

The effects of surface traction characteristics on frictional demand and kinematics in tennis.

The interaction between footwear and surfaces influences the forces experienced by tennis players. The purpose of this study was to investigate traction demand and kinematic adaptation during tennis-specific movements with changes in traction characteristics of surfaces. We hypothesised that players would increase the utilised coefficient of friction (horizontal to vertical ground reaction force ratio) when the shoe surface combination had a high coefficient of friction and flex their knee after contact to facilitate braking. Eight participants performed two separate movements, side jump out of stance and running forehand. Ground reaction force was measured and three-dimensional kinematic data were recorded. Clay surface and cushioned acrylic hard court (low vs. high shoe-surface friction) were used. The peak utilised coefficient of friction was greater on clay than the hard court. The knee was less flexed at impact on clay (-5.6 +/- 10.2 degrees) and at peak flexion (-13.1 +/- 12.0 degrees) during the running forehand. Our results indicate that tennis players adapt the level ofutilised friction according to the characteristics of the surface, and this adaptation favours sliding on the low friction surface. Less knee flexion facilitates sliding on clay, whereas greater knee flexion contributes to braking on the hard court.

Friction between human skin and incontinence pads in the presence of barrier protection products.

This novel experimental work aims to bring further knowledge of frictional performance of common barrier products used in the treatment of incontinence-associated dermatitis and determine how the skin-pad interface changes when a treatment is applied to the skin. Key data is reported and there is an in-depth analysis into friction profiles which reveals great differences between how different skin-pad tribosystems operate when exposed to commercially available barrier treatments. In a wet-pad state Barrier cream A (3M™ Cavilon™ Barrier cream) reduced friction and had much lower dynamic and static coefficients of friction than the other barrier treatments (Barrier cream B (Sorbaderm Barrier cream) and the Barrier spray C (Sorbaderm Barrier spray)). Barrier cream A provided stable friction coefficients in reciprocating sliding, whereas the other treatments, and untreated skin, did not display this unique characteristic. The barrier spray gave rise to high static friction coefficients and exhibited the most stick-slip. All three candidate barrier protection products were found to reduce directional differences in the static coefficient of friction: indicative of reduced shear loading. Knowledge of the desirable frictional properties would drive innovation in product development, and benefit companies, clinicians and users.

Effect of seasonal change on the biomechanical and physical properties of the human skin.

In this study, the effect of one cycle of winter to summer seasonal transition on the mechanical and physical properties of skin was investigated in vivo. Fourteen healthy skin volunteers aged between 22 and 42 years were studied at the volar lower and upper arms. The findings indicate a 22.15% and 34.29% decrease in trans-epidermal water loss (TEWL) and the average epidermal roughness (AER), respectively. Also, improved skin properties were observed such as a 25.48% rise in average epidermal hydration (AEH), 22.59% in skin thickness, 38.64% and 21.92% in melanin and redness, respectively, as well as an 8.25% rise in its firmness and 23.14% in elasticity when strained with uniaxial deformations. An inverse correlation was established between TEWL and AEH with a linear relationship between stratum corneum roughness versus TEWL as well as thickness and hydration. Also, the skin firmness exhibited a direct proportionality with TEWL and an inverse correlation with skin hydration where these relationships were stronger in summer than in winter. Furthermore, time-dependent results demonstrated three-staged elastic, viscoelastic and creep deformations with high, moderate and low strain rates respectively at both anatomical locations. The winter season displayed lower skin firmness and elasticity of 0.37 mm and 0.04 mm compared to 0.40 mm and 0.06 mm in summer accordingly. Anatomically, the two arm regions displayed different results with the upper arm having more consistent results than the lower arm. These results will find relevance in sensor skins and exoskeletons in Medicare, robotic and military technologies as well as innovations in cosmetics and dermatology.

The development of a new artificial model of a finger for assessing transmitted vibrations.

Prolonged exposure of the hand to tool-induced vibrations is associated with the occurrence of conditions such as vibration white finger. This study involves the development of a new artificial model that approximates both loading and vibration behaviour of the human finger. The layered system uses polypropylene "bones", encased in a cylinder of low modulus, room-temperature curing silicone gel (to replicate subcutaneous tissues), with an outer layer of latex (to replicate the dermis and epidermis). A protocol for manufacture was developed and dynamic mechanical analysis was carried out on a range of gels in order to choose a range close to the mechanical properties of the human finger. The load-deflection behaviour under quasi-static loading was obtained using an indenter. The indentation measurements were then compared with a set of validation data obtained from human participant testing under the same conditions. A 2-D FE model of the finger was also used to assess vibration responses using existing parameters for a human finger and those obtained from the tested materials. Vibration analysis was conducted under swept sinusoidal excitations ranging from 10 to 400Hz whilst the FE finger model was pressed 6mm toward the handle. Results were found to compare well. This synthetic test-bed and protocol can now be used in future experiments for assessing finger-transmitted vibrations. For instance, it can aid in assessing anti-vibration glove materials without the need for human subjects and provide consistent control of test parameters such as grip force.

Sub-clinical assessment of atopic dermatitis severity using angiographic optical coherence tomography.

Measurement of sub-clinical atopic dermatitis (AD) is important for determining how long therapies should be continued after clinical clearance of visible AD lesions. An important biomarker of sub-clinical AD is epidermal hypertrophy, the structural measures of which often make optical coherence tomography (OCT) challenging due to the lack of a clearly delineated dermal-epidermal junction in AD patients. Alternatively, angiographic OCT measurements of vascular depth and morphology may represent a robust biomarker for quantifying the severity of clinical and sub-clinical AD. To investigate this, angiographic data sets were acquired from 32 patients with a range of AD severities. Deeper vascular layers within skin were found to correlate with increasing clinical severity. Furthermore, for AD patients exhibiting no clinical symptoms, the superficial plexus depth was found to be significantly deeper than healthy patients at both the elbow (p = 0.04) and knee (p<0.001), suggesting that sub-clinical changes in severity can be detected. Furthermore, the morphology of vessels appeared altered in patients with severe AD, with significantly different vessel diameter, length, density and fractal dimension. These metrics provide valuable insight into the sub-clinical severity of the condition, allowing the effects of treatments to be monitored past the point of clinical remission.

How do gloves affect cutaneous sensibility in medical practice? Two new applied tests.

In order to quantify the effect of medical gloves on tactile performance, two new Simulated Medical Examination Tactile Tests (SMETT) have been developed to replicate the tactile and haptic ability required in medical examinations: the 'Bumps' test and the 'Princess and the Pea' (P&P) test. A pilot study was carried out using 30-40 subjects for each test in order to investigate the suitability of the tests for medical glove evaluation. Tests were performed with latex and nitrile examination gloves and without gloves. Following the tests, small-scale studies were carried out to investigate the effect of various design parameters, such as material stiffness and tactile exploration method. In the 'Bumps' test, subjects performed significantly better in the ungloved condition, and there were 'almost significant' differences between the gloves, with the thinner latex gloves performing better than the thicker nitrile gloves. Both finger orientation and surface lubrication were found to have a significant effect on results, indicating that these need to be clearly defined in the test procedure. In the 'P&P' test, no significant effect of hand condition was found, suggesting that haptic sensing is less affected by medical gloves than cutaneous sensibility. Other factors such as material stiffness, technique and test orientation had a more significant effect. The SMETT 'Bumps' test has potential as a clinical manual performance evaluation tool and may be used to evaluate the relative effects of different gloves. The SMETT 'P&P' test is a valid measure of haptic or tactile performance, but should not be used in glove evaluation. Both tests could have further applications, such as in the assessment of neurological impairment or aptitude testing for potential surgeons.

Biomechanical responses to changes in friction on a clay court surface.

OBJECTIVES: To examine the influence of clay court frictional properties on tennis players' biomechanical response. DESIGN: Repeated measures. METHODS: Lower limb kinematic and force data were collected on sixteen university tennis players during 10×180° turns (running approach speed 3.9±0.20ms-1) on a synthetic clay surface of varying friction levels. To adjust friction levels the volume of sand infill above the force plate was altered (kg per m2 surface area; 12, 16 and 20kgm-2). Repeated measures ANOVA and Bonferroni's corrected alpha post-hoc analyses were conducted to identify significant differences in lower limb biomechanics between friction levels. RESULTS: Greater sliding distances (ηp2=0.355, p=0.008) were observed for the lowest friction condition (20kgm-2) compared to the 12 and 16kgm-2 conditions. No differences in ankle joint kinematics and knee flexion angles were observed. Later peak knee flexion occurred on the 20kgm-2 condition compared to the 12kgm-2 (ηp2=0.270, p=0.023). Lower vertical (ηp2=0.345, p=0.027) and shear (ηp2=0.396, p=0.016) loading rates occurred for the 20kgm2 condition compared to the 16kgm2. CONCLUSIONS: Lower loading rates and greater sliding distances when clay surface friction was reduced suggests load was more evenly distributed over time reducing players' injury risks. The greater sliding distances reported were accompanied with later occurrence of peak knee flexion, suggesting longer time spent braking and a greater requirement for muscular control increasing the likelihood of fatigue.

Controlled peel testing of a model tissue for diseased aorta.

In this study, we examine the effect of collagenase, elastase and glutaraldehyde treatments on the response of porcine aorta to controlled peel testing. Specifically, the effects on the tissue׳s resistance to dissection, as quantified by critical energy release rate, are investigated. We further explore the utility of these treatments in creating model tissues whose properties emulate those of certain diseased tissues. Such model tissues would find application in, for example, development and physical testing of new endovascular devices. Controlled peel testing of fresh and treated aortic specimens was performed with a tensile testing apparatus. The resulting reaction force profiles and critical energy release rates were compared across sample classes. It was found that collagenase digestion significantly decreases resistance to peeling, elastase digestion has almost no effect, and glutaraldehyde significantly increases resistance. The implications of these findings for understanding mechanisms of disease-associated biomechanical changes, and for the creation of model tissues that emulate these changes are explored.

Creating a model of diseased artery damage and failure from healthy porcine aorta.

Large quantities of diseased tissue are required in the research and development of new generations of medical devices, for example for use in physical testing. However, these are difficult to obtain. In contrast, porcine arteries are readily available as they are regarded as waste. Therefore, reliable means of creating from porcine tissue physical models of diseased human tissue that emulate well the associated mechanical changes would be valuable. To this end, we studied the effect on mechanical response of treating porcine thoracic aorta with collagenase, elastase and glutaraldehyde. The alterations in mechanical and failure properties were assessed via uniaxial tension testing. A constitutive model composed of the Gasser-Ogden-Holzapfel model, for elastic response, and a continuum damage model, for the failure, was also employed to provide a further basis for comparison (Calvo and Peña, 2006; Gasser et al., 2006). For the concentrations used here it was found that: collagenase treated samples showed decreased fracture stress in the axial direction only; elastase treated samples showed increased fracture stress in the circumferential direction only; and glutaraldehyde samples showed no change in either direction. With respect to the proposed constitutive model, both collagenase and elastase had a strong effect on the fibre-related terms. The model more closely captured the tissue response in the circumferential direction, due to the smoother and sharper transition from damage initiation to complete failure in this direction. Finally, comparison of the results with those of tensile tests on diseased tissues suggests that these treatments indeed provide a basis for creation of physical models of diseased arteries.

Developing CT based computational models of pediatric femurs.

The mechanisms of fracture in infants and toddlers are not well understood. There have been very few studies on the mechanical properties of pediatric bones and their responses under fracture loading. A better understanding of fracture mechanisms in children will help elucidate both accidental and non-accidental injuries, as well as bone fragility diseases. The aim of this study is to develop in silico femoral models from CT scans to provide detailed quantitative information regarding the geometry and mechanical response of the femur, with the long term potential of investigating injury mechanisms. Fifteen anonymized QCT scans (aged 0-3 years) were collected and used to create personalized computational models of femurs. The elastic modulus of femur was illustrated at various ages. The models were also subjected to a series of four point bending simulations taking into account a range of loads perpendicular to the femoral shaft. The results showed that mid-shaft cross-section at birth appeared circular, but the diameter in the anteroposterior axis gradually increased with age. The density, and by implication modulus of elasticity at the mid-shaft became more differentiated with growth. Pediatric cortical bone with density close to the peak values found in adults was attained a few weeks after birth. The method is able to capture quantitative variations in geometries, material properties and mechanical responses, and has confirmed the rapid development of bone during the first few years of life using in silico models.

A study of clinicians' views on medical gloves and their effect on manual performance.

BACKGROUND: The effect of gloves on practitioners' performance has not been a major factor in their design. To determine the critical elements of performance and design appropriate tests, data from clinicians were needed. METHODS: Semistructured interviews were carried out with medical practitioners from various disciplines, in which they were asked about their glove use, their views on gloves, medical tasks requiring the highest manual performance or most affected by gloves, and what the main issues with glove use were. RESULTS: Many participants expressed a preference for latex over nitrile, with glove fit being the main reason given. Satisfaction with surgical gloves (generally latex) was high but less so with examination gloves, which were generally nitrile. Tactile sensation, comfort, and donning were also seen as major issues with glove use. A number of tasks were identified for possible development as tests. CONCLUSION: Performance in medical practice needs to be clearly defined, separating perceived and measured performance, and understanding the effect of glove material, fit, and thickness. Development of new glove performance tests based on the tasks identified is an important part of this.