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Vilhena L, Afonso L, Ramalho A. Skin Friction: Mechanical and Tribological Characterization of Different Papers Used in Everyday Life. MATERIALS (BASEL, SWITZERLAND) 2023; 16:5724. [PMID: 37630015 PMCID: PMC10456811 DOI: 10.3390/ma16165724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 02/08/2023] [Accepted: 02/10/2023] [Indexed: 08/27/2023]
Abstract
The coefficient of friction for different contacting materials against skin is mainly influenced by the nature of the materials (synthetic and natural fabrics), mechanical contact parameters (interfacial pressure and sliding velocities), and physiological skin conditions (ambient humidity and skin moisture content). In the present research work, seven different types of papers used in everyday life were analyzed. The physical properties of these materials were determined through tensile tests and friction tests. By comparing mechanical properties with coefficient of friction, it was possible to conclude that the coefficient of friction is strongly correlated with the mechanical properties.
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Affiliation(s)
- Luís Vilhena
- Centre for Mechanical Engineering, Materials and Processes (CEMMPRE), Department of Mechanical Engineering, University of Coimbra, 3030-788 Coimbra, Portugal
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Liu J, Zhang Q, Liu X. Understanding handling performance of rugby balls under wet conditions: analysis of finger-ball friction. INT J PERF ANAL SPOR 2020. [DOI: 10.1080/24748668.2020.1786299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Jiaojiao Liu
- The School of Sports and Physical Education, Shandong Sport University, Rizhao, Shandong, China
| | - Qian Zhang
- The Faculty of Engineering and Technology, Liverpool John Moores University, Liverpool, UK
| | - Xiaoxiao Liu
- The Faculty of Engineering and Technology, Liverpool John Moores University, Liverpool, UK
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3
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Sirin O, Barrea A, Lefèvre P, Thonnard JL, Basdogan C. Fingerpad contact evolution under electrovibration. J R Soc Interface 2019; 16:20190166. [PMID: 31362623 DOI: 10.1098/rsif.2019.0166] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Displaying tactile feedback through a touchscreen via electrovibration has many potential applications in mobile devices, consumer electronics, home appliances and automotive industry though our knowledge and understanding of the underlying contact mechanics are very limited. An experimental study was conducted to investigate the contact evolution between the human finger and a touch screen under electrovibration using a robotic set-up and an imaging system. The results show that the effect of electrovibration is only present during full slip but not before slip. Hence, the coefficient of friction increases under electrovibration as expected during full slip, but the apparent contact area is significantly smaller during full slip when compared to that of no electrovibration condition. It is suggested that the main cause of the increase in friction during full slip is due to an increase in the real contact area and the reduction in apparent area is due to stiffening of the finger skin in the tangential direction.
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Affiliation(s)
- Omer Sirin
- College of Engineering, Robotics and Mechatronics Laboratory, Koc University, 34450 Istanbul, Turkey
| | - Allan Barrea
- Institute of Neuroscience (IoNS), Electronics and Applied Mathematics (ICTEAM), Université catholique de Louvain, Louvain-la-Neuve, Belgium.,Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Philippe Lefèvre
- Institute of Neuroscience (IoNS), Electronics and Applied Mathematics (ICTEAM), Université catholique de Louvain, Louvain-la-Neuve, Belgium.,Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Jean-Louis Thonnard
- Institute of Neuroscience (IoNS), Electronics and Applied Mathematics (ICTEAM), Université catholique de Louvain, Louvain-la-Neuve, Belgium.,Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Cagatay Basdogan
- College of Engineering, Robotics and Mechatronics Laboratory, Koc University, 34450 Istanbul, Turkey
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Sergachev D, Matthews D, van der Heide E. An Empirical Approach for the Determination of Skin Elasticity: Finger pad Friction against Textured Surfaces. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.biotri.2019.100097] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Dzidek B, Bochereau S, Johnson SA, Hayward V, Adams MJ. Why pens have rubbery grips. Proc Natl Acad Sci U S A 2017; 114:10864-10869. [PMID: 28973874 PMCID: PMC5642691 DOI: 10.1073/pnas.1706233114] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The process by which human fingers gives rise to stable contacts with smooth, hard objects is surprisingly slow. Using high-resolution imaging, we found that, when pressed against glass, the actual contact made by finger pad ridges evolved over time following a first-order kinetics relationship. This evolution was the result of a two-stage coalescence process of microscopic junctions made between the keratin of the stratum corneum of the skin and the glass surface. This process was driven by the secretion of moisture from the sweat glands, since increased hydration in stratum corneum causes it to become softer. Saturation was typically reached within 20 s of loading the contact, regardless of the initial moisture state of the finger and of the normal force applied. Hence, the gross contact area, frequently used as a benchmark quantity in grip and perceptual studies, is a poor reflection of the actual contact mechanics that take place between human fingers and smooth, impermeable surfaces. In contrast, the formation of a steady-state contact area is almost instantaneous if the counter surface is soft relative to keratin in a dry state. It is for this reason that elastomers are commonly used to coat grip surfaces.
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Affiliation(s)
- Brygida Dzidek
- School of Engineering, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Séréna Bochereau
- Sorbonne Universités, Université Pierre et Marie Curie Univ Paris 06, Institut des Systèmes Intelligents et de Robotique, F-75005 Paris, France
| | - Simon A Johnson
- Unilever Research & Development Port Sunlight, Bebington, Wirral CH63 3JW, United Kingdom
| | - Vincent Hayward
- Sorbonne Universités, Université Pierre et Marie Curie Univ Paris 06, Institut des Systèmes Intelligents et de Robotique, F-75005 Paris, France
| | - Michael J Adams
- School of Engineering, University of Birmingham, Birmingham B15 2TT, United Kingdom;
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Liu X, Carré MJ, Zhang Q, Lu Z, Matcher SJ, Lewis R. Measuring contact area in a sliding human finger-pad contact. Skin Res Technol 2017; 24:31-44. [PMID: 28573767 DOI: 10.1111/srt.12387] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/26/2017] [Indexed: 11/26/2022]
Abstract
BACKGROUND/PURPOSE The work outlined in this paper was aimed at achieving further understanding of skin frictional behaviour by investigating the contact area between human finger-pads and flat surfaces. METHODS Both the static and the dynamic contact areas (in macro- and micro-scales) were measured using various techniques, including ink printing, optical coherence tomography (OCT) and Digital Image Correlation (DIC). RESULTS In the studies of the static measurements using ink printing, the experimental results showed that the apparent and the real contact area increased with load following a piecewise linear correlation function for a finger-pad in contact with paper sheets. Comparisons indicated that the OCT method is a reliable and effective method to investigate the real contact area of a finger-pad and allow micro-scale analysis. The apparent contact area (from the DIC measurements) was found to reduce with time in the transition from the static phase to the dynamic phase while the real area of contact (from OCT) increased. CONCLUSIONS The results from this study enable the interaction between finger-pads and contact object surface to be better analysed, and hence improve the understanding of skin friction.
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Affiliation(s)
- X Liu
- The Department of Mechanical Engineering, The University of Sheffield, Sheffield, UK
| | - M J Carré
- The Department of Mechanical Engineering, The University of Sheffield, Sheffield, UK
| | - Q Zhang
- The Department of Electronic and Electrical Engineering, Liverpool John Moores University, Liverpool, UK
| | - Z Lu
- The Department of Electronic and Electrical Engineering, The University of Sheffield, Sheffield, UK
| | - S J Matcher
- The Department of Electronic and Electrical Engineering, The University of Sheffield, Sheffield, UK
| | - R Lewis
- The Department of Mechanical Engineering, The University of Sheffield, Sheffield, UK
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Leyva-Mendivil MF, Lengiewicz J, Page A, Bressloff NW, Limbert G. Skin Microstructure is a Key Contributor to Its Friction Behaviour. TRIBOLOGY LETTERS 2017; 65:12. [PMID: 32009774 PMCID: PMC6961497 DOI: 10.1007/s11249-016-0794-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 11/21/2016] [Indexed: 05/06/2023]
Abstract
Due to its multifactorial nature, skin friction remains a multiphysics and multiscale phenomenon poorly understood despite its relevance for many biomedical and engineering applications (from superficial pressure ulcers, through shaving and cosmetics, to automotive safety and sports equipment). For example, it is unclear whether, and in which measure, the skin microscopic surface topography, internal microstructure and associated nonlinear mechanics can condition and modulate skin friction. This study addressed this question through the development of a parametric finite element contact homogenisation procedure which was used to study and quantify the effect of the skin microstructure on the macroscopic skin frictional response. An anatomically realistic two-dimensional image-based multilayer finite element model of human skin was used to simulate the sliding of rigid indenters of various sizes over the skin surface. A corresponding structurally idealised multilayer skin model was also built for comparison purposes. Microscopic friction specified at skin asperity or microrelief level was an input to the finite element computations. From the contact reaction force measured at the sliding indenter, a homogenised (or apparent) macroscopic friction was calculated. Results demonstrated that the naturally complex geometry of the skin microstructure and surface topography alone can play as significant role in modulating the deformation component of macroscopic friction and can significantly increase it. This effect is further amplified as the ground-state Young's modulus of the stratum corneum is increased (for example, as a result of a dryer environment). In these conditions, the skin microstructure is a dominant factor in the deformation component of macroscopic friction, regardless of indenter size or specified local friction properties. When the skin is assumed to be an assembly of nominally flat layers, the resulting global coefficient of friction is reduced with respect to the local one. This seemingly counter-intuitive effect had already been demonstrated in a recent computational study found in the literature. Results also suggest that care should be taken when assigning a coefficient of friction in computer simulations, as it might not reflect the conditions of microscopic and macroscopic friction one intends to represent. The modelling methodology and simulation tools developed in this study go beyond what current analytical models of skin friction can offer: the ability to accommodate arbitrary kinematics (i.e. finite deformations), nonlinear constitutive properties and the complex geometry of the skin microstructural constituents. It was demonstrated how this approach offered a new level of mechanistic insight into plausible friction mechanisms associated with purely structural effects operating at the microscopic scale; the methodology should be viewed as complementary to physical experimental protocols characterising skin friction as it may facilitate the interpretation of observations and measurements and/or could also assist in the design of new experimental quantitative assays.
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Affiliation(s)
- Maria F. Leyva-Mendivil
- National Centre for Advanced Tribology at Southampton (nCATS), Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ UK
- Bioengineering Science Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ UK
| | - Jakub Lengiewicz
- Institute of Fundamental Technological Research, Polish Academy of Sciences (IPPT PAN), ul. Pawinskiego 5B, 02-106 Warsaw, Poland
| | - Anton Page
- Biomedical Imaging Unit, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, SO16 6YDJ UK
| | - Neil W. Bressloff
- Computational Engineering and Design Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ UK
| | - Georges Limbert
- National Centre for Advanced Tribology at Southampton (nCATS), Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ UK
- Bioengineering Science Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ UK
- Laboratory of Biomechanics and Mechanobiology, Division of Biomedical Engineering, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town, 7935 South Africa
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Morales Hurtado M, de Vries EG, Zeng X, van der Heide E. A tribo-mechanical analysis of PVA-based building-blocks for implementation in a 2-layered skin model. J Mech Behav Biomed Mater 2016; 62:319-332. [PMID: 27236420 DOI: 10.1016/j.jmbbm.2016.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 04/28/2016] [Accepted: 05/02/2016] [Indexed: 01/14/2023]
Abstract
Poly(vinyl) alcohol hydrogel (PVA) is a well-known polymer widely used in the medical field due to its biocompatibility properties and easy manufacturing. In this work, the tribo-mechanical properties of PVA-based blocks are studied to evaluate their suitability as a part of a structure simulating the length scale dependence of human skin. Thus, blocks of pure PVA and PVA mixed with Cellulose (PVA-Cel) were synthesised via freezing/thawing cycles and their mechanical properties were determined by Dynamic Mechanical Analysis (DMA) and creep tests. The dynamic tests addressed to elastic moduli between 38 and 50kPa for the PVA and PVA-Cel, respectively. The fitting of the creep compliance tests in the SLS model confirmed the viscoelastic behaviour of the samples with retardation times of 23 and 16 seconds for the PVA and PVA-Cel, respectively. Micro indentation tests were also achieved and the results indicated elastic moduli in the same range of the dynamic tests. Specifically, values between 45-55 and 56-81kPa were obtained for the PVA and PVA-Cel samples, respectively. The tribological results indicated values of 0.55 at low forces for the PVA decreasing to 0.13 at higher forces. The PVA-Cel blocks showed lower friction even at low forces with values between 0.2 and 0.07. The implementation of these building blocks in the design of a 2-layered skin model (2LSM) is also presented in this work. The 2LSM was stamped with four different textures and their surface properties were evaluated. The hydration of the 2LSM was also evaluated with a corneometer and the results indicated a gradient of hydration comparable to the human skin.
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Affiliation(s)
- M Morales Hurtado
- Surface Technology and Tribology Group, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands.
| | - E G de Vries
- Surface Technology and Tribology Group, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands
| | - X Zeng
- Surface Technology and Tribology Group, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands; Advanced lubricating Materials Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Haike Road 100, Pudong, Shanghai, China
| | - E van der Heide
- Surface Technology and Tribology Group, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands; TU Delft, Faculty of Civil Engineering and Geosciences, Stevinweg 1, 2628 CN Delft, The Netherlands
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9
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Loeve AJ, Bilo RAC, Emirdag E, Sharify M, Jansen FW, Dankelman J. In vitro validation of vaginal sampling in rape victims: the problem of Locard's principle. Forensic Sci Med Pathol 2013; 9:154-62. [PMID: 23526354 DOI: 10.1007/s12024-013-9426-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2013] [Indexed: 11/24/2022]
Abstract
PURPOSE Intra-vaginal traces can serve as supporting physical evidence of vaginal penetration in sex-crime cases. Vaginal trace sampling guidelines prescribe using a speculum and swabs or swabs only. The use of Locard's exchange theory requires samples of trace materials to always be contamination-free and of accurately known origin. If traces from the outer genital area are accidentally introduced into the vagina during sampling, these traces may be recorded as originating in a location where they were not present at the time of evidence collection. The goal of this study was to assess the risks of false positive findings in vitro of traces found inside the vagina due to trace dislocation caused by current vaginal trace sampling methods (swab-only or with speculum), and for a new method that uses a sleeve accessory to prevent trace dislocation. METHODS Starch solution was applied to the labia of three clean female genitalia mock-ups with vaginas of various diameters and structures. The speculum, swab-only, and sleeve methods were each used 30 times on each mock-up, giving a total of 90 repetitions of each method. Iodine was used to determine whether any starch traces had been introduced vaginally. RESULTS The speculum and swab-only methods gave 100 and 63-87 % false positive results respectively due to trace dislocation. The sleeve method reduced this to 2 % (0 % after correction). CONCLUSIONS The results suggest that there is a need to conduct clinical in vivo studies to determine whether these results translate into everyday practice and to ensure reliable trace sampling in sex-crime cases.
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Affiliation(s)
- Arjo J Loeve
- Department of BioMechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, 8-C-01, Mekelweg 2, 2628 CD, Delft, The Netherlands.
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10
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Adams MJ, Johnson SA, Lefèvre P, Lévesque V, Hayward V, André T, Thonnard JL. Finger pad friction and its role in grip and touch. J R Soc Interface 2012; 10:20120467. [PMID: 23256185 DOI: 10.1098/rsif.2012.0467] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Many aspects of both grip function and tactile perception depend on complex frictional interactions occurring in the contact zone of the finger pad, which is the subject of the current review. While it is well established that friction plays a crucial role in grip function, its exact contribution for discriminatory touch involving the sliding of a finger pad is more elusive. For texture discrimination, it is clear that vibrotaction plays an important role in the discriminatory mechanisms. Among other factors, friction impacts the nature of the vibrations generated by the relative movement of the fingertip skin against a probed object. Friction also has a major influence on the perceived tactile pleasantness of a surface. The contact mechanics of a finger pad is governed by the fingerprint ridges and the sweat that is exuded from pores located on these ridges. Counterintuitively, the coefficient of friction can increase by an order of magnitude in a period of tens of seconds when in contact with an impermeably smooth surface, such as glass. In contrast, the value will decrease for a porous surface, such as paper. The increase in friction is attributed to an occlusion mechanism and can be described by first-order kinetics. Surprisingly, the sensitivity of the coefficient of friction to the normal load and sliding velocity is comparatively of second order, yet these dependencies provide the main basis of theoretical models which, to-date, largely ignore the time evolution of the frictional dynamics. One well-known effect on taction is the possibility of inducing stick-slip if the friction decreases with increasing sliding velocity. Moreover, the initial slip of a finger pad occurs by the propagation of an annulus of failure from the perimeter of the contact zone and this phenomenon could be important in tactile perception and grip function.
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Affiliation(s)
- Michael J Adams
- School of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, UK.
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Masen M. A systems based experimental approach to tactile friction. J Mech Behav Biomed Mater 2011; 4:1620-6. [DOI: 10.1016/j.jmbbm.2011.04.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 04/04/2011] [Accepted: 04/11/2011] [Indexed: 11/28/2022]
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Cottenden AM, Wong WK, Cottenden DJ, Farbrot A. Development and validation of a new method for measuring friction between skin and nonwoven materials. Proc Inst Mech Eng H 2008; 222:791-803. [DOI: 10.1243/09544119jeim313] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A new method for measuring the coefficient of friction between nonwoven materials and the curved surface of the volar forearm has been developed and validated. The method was used to measure the coefficient of static friction for three different nonwoven materials on the normal (dry) and over-hydrated volar forearms of five female volunteers (ages 18–44). The method proved simple to run and had good repeatability: the coefficient of variation (standard deviation expressed as a percentage of the mean) for triplets of repeat measurements was usually (80 per cent of the time) less than 10 per cent. Measurements involving the geometrically simpler configuration of pulling a weighted fabric sample horizontally across a quasi-planar area of volar forearm skin proved experimentally more difficult and had poorer repeatability. However, correlations between values of coefficient of static friction derived using the two methods were good ( R = 0.81 for normal (dry) skin, and 0.91 for over-hydrated skin). Measurements of the coefficient of static friction for the three nonwovens for normal (dry) and for over-hydrated skin varied in the ranges of about 0.3–0.5 and 0.9–1.3, respectively. In agreement with Amontons' law, coefficients of friction were invariant with normal pressure over the entire experimental range (0.1–8.2 kPa).
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Affiliation(s)
- A M Cottenden
- Department of Medical Physics and Bioengineering, University College London, London, UK
| | - W K Wong
- Department of Medical Physics and Bioengineering, University College London, London, UK
| | - D J Cottenden
- Department of Medical Physics and Bioengineering, University College London, London, UK
| | - A Farbrot
- SCA Hygiene Products AB, Gothenburg, Sweden
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Abstract
BACKGROUND/PURPOSE Friction studies are useful in quantitatively investigating the skin surface. Previous studies utilized different apparatuses and materials for these investigations but there was no real-time test parameter control or monitoring. Our studies incorporated the commercially available UMT Series Micro-Tribometer, a tribology instrument that permits real-time monitoring and calculation of the important parameters in friction studies, increasing the accuracy over previous tribology and friction measurement devices used on skin. METHODS Our friction tests were performed on four healthy volunteers and on abdominal skin samples. A stainless steel ball was pressed on to the skin with at a pre-set load and then moved across the skin at a constant velocity of 5 mm/min. The UMT continuously monitored the friction force of the skin and the normal force of the ball to calculate the friction coefficient in real-time. Tests investigated the applicability of Amonton's law, the impact of increased and decreased hydration, and the effect of the application of moisturizers. RESULTS The friction coefficient depends on the normal load applied, and Amonton's law does not provide an accurate description for the skin surface. Application of water to the skin increased the friction coefficient and application of isopropyl alcohol decreased it. Fast acting moisturizers immediately increased the friction coefficient, but did not have the prolonged effect of the slow, long lasting moisturizers. CONCLUSION The UMT is capable of making real-time measurements on the skin and can be used as an effective tool to study friction properties. Results from the UMT measurements agree closely with theory regarding the skin surface.
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Sivamani RK, Goodman J, Gitis NV, Maibach HI. Coefficient of friction: tribological studies in man - an overview. Skin Res Technol 2003; 9:227-34. [PMID: 12877683 DOI: 10.1034/j.1600-0846.2003.02366.x] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND/PURPOSE Compared to other studies of skin, relatively few studies have focused on the friction of skin. This work reviews existing skin friction, emphasizing test apparatuses and parameters that have added to information regarding the friction coefficient. This review also outlines what factors are important to consider in future friction studies. METHODS Past studies have utilized numerous designs for a test apparatus, including probe geometry and material, as well as various probe motions (rotational vs. linear). Most tests were performed in vivo; a few were performed in vitro and on porcine skin. RESULTS Differences in probe material, geometry and smoothness affect friction coefficient measurements. An increase in skin hydration, either through water or through moisturizer application, increases its friction coefficient; a decrease in skin hydration, either through clinical dermatitis or through alcohol addition, decreases the coefficient. Differences are present between anatomical sites. Conflicting results are found regarding age and no differences are apparent as a result of gender or race. CONCLUSION Skin friction appears to be dependent on several factors - such as age, anatomical site and skin hydration. The choice of the probe and the test apparatus also influence the measurement.
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