A systems based experimental approach to tactile friction

Masen, Marc Arthur

doi:10.1016/j.jmbbm.2011.04.007

Cited by 61 publications

(74 citation statements)

References 28 publications

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“…These experimental studies showed contradicting or inconclusive results: Egawa et al [50] indicated that the skin surface roughness, even though not correlated with skin friction, improved the predictability of the coefficient of friction when analysed along skin moisture in multiregression analyses; Nakajima and Narasaka [24] showed that the density of the skin primary furrows is correlated with skin friction, but also found correlation between furrow density and elasticity; however, it is unclear which of these factors dominates the skin friction response [2]. A detailed overview of our current understanding of skin friction can be found in recent seminal papers [2,7,12,23,27,33]. In most of these studies, the topographic features of the skin are assumed to provide negligible or no contribution to the skin global friction response, because of the high compliance of the skin compared to that of the indenter.…”

Section: Introductionmentioning

confidence: 99%

Skin Microstructure is a Key Contributor to Its Friction Behaviour

et al. 2016

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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

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Section: Introductionmentioning

confidence: 99%

Skin Microstructure is a Key Contributor to Its Friction Behaviour

et al. 2016

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“…Hendriks and Franklin [49] reported a factor 5 decrease in the coefficient of friction measured on skin when the roughness of the counter material was increased from 0.1 to 10 μm, from which the exponent h can be estimated to be approximately −2. In contrast, based on a fully elastic approximation combined with a GreenwoodWilliamson-like statistical approach, Masen [50] estimated h to range between −0.66 and −1. However, this latter estimate is an over-simplification because the mechanical properties of skin vary with the size of the contact [39], and a deterministic approach to account for the effects of surface roughness seems more appropriate.…”

Section: Changing Friction By Surface Texturementioning

confidence: 99%

Skin tribology: Science friction?

2013

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Abstract:The application of tribological knowledge is not just restricted to optimizing mechanical and chemical engineering problems. In fact, effective solutions to friction and wear related questions can be found in our everyday life. An important part is related to skin tribology, as the human skin is frequently one of the interacting surfaces in relative motion. People seem to solve these problems related to skin friction based upon a trial-anderror strategy and based upon on our sense for touch. The question of course rises whether or not a trained tribologist would make different choices based upon a science based strategy? In other words: Is skin friction part of the larger knowledge base that has been generated during the last decades by tribology research groups and which could be referred to as Science Friction? This paper discusses the specific nature of tribological systems that include the human skin and argues that the living nature of skin limits the use of conventional methods. Skin tribology requires in vivo, subject and anatomical location specific test methods. Current predictive friction models can only partially be applied to predict in vivo skin friction. The reason for this is found in limited understanding of the contact mechanics at the asperity level of product-skin interactions. A recently developed model gives the building blocks for enhanced understanding of friction at the micro scale. Only largely simplified power law based equations are currently available as general engineering tools. Finally, the need for friction control is illustrated by elaborating on the role of skin friction on discomfort and comfort. Surface texturing and polymer brush coatings are promising directions as they provide way and means to tailor friction in sliding contacts without the need of major changes to the product.Keywords: friction; bio-tribology; skin; soft tissue; surface texture; brush coatings Skin friction in daily lifeThe application of tribological knowledge, i.e., knowledge on the science and technology of interacting surfaces in relative motion, is not restricted to optimizing mechanical and chemical engineering problems. In fact, effective solutions to tribology related questions are evident in our everyday life, as illustrated in fascinating examples described by D. Dowson's "A tribological day" [1]. An important part of the effective solutions in daily life situations is related to skin tribology, as the human skin is frequently one of the interacting surfaces in relative motion. These questions are typically related to optimizing friction and lubrication problems in skin-product interactions, rather than to optimising wear. Take for example the swimming pool or bathroom where material selection and application of anti-slip coatings prevent us from falling when the floor gets wet. Yet, if such coatings do not sufficiently increase friction, one will optimize the tribological system, e.g., by pressing our full foot to the floor and subsequently increasing the true area of contact or by chan...

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“…The interaction between finger and stimulus is complex, involving deformation of the finger from pressure and the vibratory information from movement (Childs & Henson, 2007;Derler, Gerhardt, Lenz, Bertaux & Hadad, 2010) as well as topographical and material characteristics (Tomlinson, Lewis & Carre, 2009;Masen, 2011). Thus, when the finger slides over the material there will be both frictional forces and vibrations (Mate & Carpick, 2011;Bensmaïa & Hollins, 2003).…”

Section: Study III Backgroundmentioning

confidence: 99%

“…Much attention and research have been dedicated to measure friction with artificial probes designed to mimic human fingers or to develop measurement models with fingers (e.g. Derler, Gerhardt, Lenz, Bertaux, & Hadad, 2009;Tomlinson, Lewis, & Carre, 2009;Masen, 2011). The benefits of such probes are obvious in its standardization and quality of measurement.…”

Section: Main Findingsmentioning

confidence: 99%

Getting a Feel for Tactile Space: Exploring Haptic Perception of Microtexture

Arvidsson¹

2012

PsycEXTRA Dataset

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The present thesis is based on three studies that research different aspects of fine texture perception. The goal is to better understand the mechanisms involved in haptic perception of textures below 200 µm, also known as microtextures. Study I was conducted to establish a friction measurement model and relating the friction measurements to perceived coarseness of fine textures. A set of printing papers was used as stimulus material. In Study II an expanded set, including the set of Study I, was used as stimuli in a multidimensional scaling (MDS) experiment of haptic fine texture perception. Through scaling of perceptual attributes and similarities, a three dimensional space was found to best describe the data and the dimensions were interpreted as rough-smooth, thick-thin and distinct-indistinct. In Study III a series of model surfaces were manufactured with a systematically varied sinusoidal pattern, spanning from 300 nm to 80 µm. As in Study II, a similarity experiment was conducted and a two dimensional space was chosen, the dimensions of which were explained well through friction and the wavelength. Together these three studies form a better picture of fine texture perception. The dimensionality found with paper stimuli was very similar to the corresponding spaces for marcrotextures of everyday materials, even though a different perceptual system is used for fine texture perception. Regardless if the information is coded through the spatial or the vibratory sense, the perception does not seem to differ in dimensionality. Further, the largest among the microtextures seem to have been perceived as carrying spatial information. On the systematically varied, rigid, textures, the MDS space did not come out in a similar fashion to those of everyday materials but instead similar to the physical properties that characterizes the change in the textures. It was further found that the participants in Study III successfully discriminated textures with an amplitude of 13 nm from the unwrinkled surfaces. From these studies the main conclusions are (a) haptically measured friction and surface roughness are important contributors to fine texture perception, (b) even at microscales, spatial information is retrieved haptically, probably through vibrations, and (c) persons can haptically discriminate textures at a nanoscale.

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A systems based experimental approach to tactile friction

Cited by 61 publications

References 28 publications

Skin Microstructure is a Key Contributor to Its Friction Behaviour

Skin Microstructure is a Key Contributor to Its Friction Behaviour

Skin tribology: Science friction?

Getting a Feel for Tactile Space: Exploring Haptic Perception of Microtexture

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