Although the human finger is the interface used for the touch process, very few studies have used its properties to provide a description of tactile perception regarding age and gender effects. Age ...and gender effects on the biophysical properties of the human finger were the main topics of our previous study. Correlating tactile perception with each parameter proved very complex. We expand on that work to assess the static and dynamic touch in addition to the touch gestures. We also investigate the age and gender effects on tactile perception by studying the finger size and the real contact area (static and dynamic) of forty human fingers of different ages and gender. The size of the finger and the real contact area (static and dynamic) define the density of the mechanoreceptors. This density is an image of the number of mechanoreceptors solicited and therefore of tactile perception (static and dynamic). In addition, the touch gestures used to perceive an object's properties differ among people. Therefore, we seek to comprehend the tactile perception of different touch gestures due to the anisotropy of mechanical properties, and we study two different directions (top to bottom and left to right).
The ensuing pilot investigation sheds new light on characterizing tumoral and non-tumoral human skin mechanical properties that will not only assist the dermatologist's diagnosis but also could ...constitute the creation of an Artificial Intelligence database for upcoming research. A modern, non-invasive, and contact-free methodology-UNDERSKIN-was developed, and hinges upon Fourier transform computations that permit the analysis of surface wave dispersion with a specific skin inversion model and viscoelastic model. It yields a detailed look at how particle movements of the medium propagate throughout its near sub-surface, hence a novel knowledge of the mechanical responses of skin tumors. The research results display the tumors' viscoelastic responses alongside their respective healthy skin outcomes for each skin layer as well as the dermatologist's touch analysis. Although dermatologists are capable of sensing and having a fair overall assessment of what they are palpating, they are unable heretofore to quantify it and inform where the firmness or softness derives from, which it is necessary to be acquainted with so as to perform an accurate diagnosis, prognosis, treatment, future surgery, and teledermatology.
The human finger plays an extremely important role in tactile perception, but little is known about the role of its biophysical properties (mechanical properties, contact properties and surface ...topography) in tactile perception. In addition, the touch gestures used to perceive an object's properties differ among people. We combined studies on the biophysical properties and the vibrations measured from the human finger to understand the age and gender effects on the tactile perception and the difference between the touch gestures. In addition, a new algorithm, Mel-frequency cepstral coefficients (MFCCs), was used to analyze the vibratory signal obtained from the physical contact of the finger, and a surface is proposed and validated. The values obtained regarding the correlation between the tribohaptic system results and the biophysical properties show that the Young's modulus and the surface topography are the most important. An inverse correlation was observed between the MFCC and the tactile perception. This last observation explained the results of better tactile perception with left to right touch gestures. It also demonstrated a better tactile perception for women.
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•An artificial finger has been developed to measure the softness of bathroom tissues.•The artificial finger measures the friction coefficient and the vibratory level.•The acoustic ...vibratory level appears as a good marker of the perceived softness.•The friction coefficient seems to be adapted for the velvetiness of the surface.•A principal component analysis permits to draw a map of papers’ tactile perception.
Tactile perception is one of the sensorial modes most stimulated by our daily environment. In particular, perceived softness is an important parameter for judging the sensory quality of surfaces and fabrics. Unfortunately, its assessment greatly depends on the tactile sense of each person, which in turn depends on many factors. Currently, the predominant method for evaluating the tactile perception of fabrics is the human handfeel panel. This qualitative approach does not permit the quantitative measure of touch feel perception.
In this study, we present a new artificial finger device to investigate the tactile sensing of ten bathroom tissues. It enables simultaneously measuring the friction and vibrations caused when sliding an artificial finger on the surface of the tissue.
The comparison between the results obtained with the artificial finger and the tactile perception evaluated using a handfeel panel showed that the artificial finger is able to separate the two parts of the tactile perception of bathroom tissues: softness and surface texture (velvetiness). The statistical analysis suggests that there is a good correlation between the vibrations measured with the artificial finger and the softness evaluated by the panel. It then shows that the friction measured by the artificial finger is related to the surface texture of a bathroom tissue. The ability of the artificial finger to mimic human touch is demonstrated. Finally, a Principal Component Analysis orders the signatures of the tactile perception of the bathroom tissues in four different groups.
The human finger plays an extremely important role in tactile perception, but little is known about how age and gender affect its biophysical properties and their role in tactile perception. We ...combined studies on contact characteristics, mechanical properties and surface topography to understand age and gender effects on the human finger. The values obtained regarding contact characteristics (i.e. adhesive force) were significantly higher for women than for men. As for mechanical properties (i.e. Young's modulus E), a significant and positive correlation with age was observed and found to be higher for women. A positive correlation was observed between age and the arithmetic mean of surface roughness for men. However, an inverse age effect was highlighted for women. The age and gender effects obtained have never been reported previously in the literature. These results open new perspectives for understanding the weakening of tactile perception across ages and how it differs between men and women.
Developing deterministic surfaces relies on controlling the structure of the rubbing interface so that not only the surface is of optimized topography, but also is able to self-adjust its ...tribological behavior according to the evolution of sliding conditions. In seeking inspirations for such designs, many engineers are turning toward the biological world to correlate surface structure to functional behavior of bio-analogs. From a tribological point of view, squamate reptiles offer diverse examples where surface texturing, submicron and nano-scale features, achieve frictional regulation. In this paper, we study the frictional response of shed skin obtained from a snake (Python regius). The study employed a specially designed tribo-acoustic probe capable of measuring the coefficient of friction and detecting the acoustical behavior of the skin in vivo. The results confirm the anisotropy of the frictional response of snakes. The coefficient of friction depends on the direction of sliding: the value in forward motion is lower than that in the backward direction. In addition it is shown that the anisotropy of the frictional response may stem from profile asymmetry of the individual fibril structures present within the ventral scales of the reptile.
► The friction profiles of the shed skin are anisotropic. The coefficient of friction exhibits dependence on the direction of sliding. ► Study of the profile of the fibril tips suggest that the observed frictional anisotropy is of geometrical origin. ► Acoustical emission, associated with friction was invariant to the direction of sliding.
Micro geometry of a gear tooth influences the contact durability and wear performance. In this paper, different gear tooth flanks have been manufactured by different finishing processes, which were ...then characterized using multiscale surface analysis, based on wavelet transform. The friction noise was then measured before and after meshing in dry and lubricated conditions, to quantify the acoustic performance of the surfaces. To accomplish this objective, a new non-destructive sensory measurement technique was developed to characterize the friction noise generated by teeth flank surface. Results show the ability of the new method to discriminate functional behavior of different surfaces as well as give possible explanations as to the contribution of tooth flank asperities during the meshing on the gear in terms of gear noise performances.
•Influence of tooth flanks surface scales on gear noise is investigated.•New non-destructive sensory measurement technique was developed to characterize friction noise.•Friction noise was measured before and after testing the gears.•Results show that this new method is suited to discriminate surfaces functionally.•Possible explanation of the contribution of tooth flank surface asperities on gear noise is given.
Saliva plays fundamental role in the maintenance of the good mouth health and in the lubrication process during oral functions including speech and mastication. Xerostomia, or dry mouth syndrome, is ...a disease due to an insufficient saliva secretion, or a total absence of saliva. The effects of xerostomia are very unpleasant in the daily life. They lead to some important inconveniences as the dental caries, the loss of teeth or some difficulties to speak.
The causes of xerostomia are various but the most of the times they are often associated to irradiation and radiotherapy used to treat cancers of the head and neck. To try to re-wet the oral cavity, salivary substitutes are generally used. They are supposed to re-lubricate the mouth.
In this work, a method for measuring adhesion and lubrication of the salivary substitutes has been tested ex vivo on pig tongue. The results indicated that the bio-adhesive properties of the salivary substitutes were fairly close to those of human saliva, while their lubricate capacity were rather less efficient. The experimental method proposed here seems to be interesting to characterise and improve the salivary substitutes performances.
•Bio-adhesion and lubrication properties of salivary substitutes were measured ex-vivo.•Bio-adhesive properties of salivary substitutes were close to those of human saliva.•Lubricant properties of salivary substitutes were lower than that of human saliva.
Background/aims: The study of changes in skin structure with age is becoming all the more important with the increase in life. The atrophy that occurs during aging is accompanied by more profound ...changes, with a loss of organization within the elastic collagen network and alterations in the basal elements. The aim of this study is to present a method to determine the mechanical properties of total human skin in vivo compared with dermal equivalents (DEs) using indentation and static friction tests.
Methods: A new bio‐tribometer working at a low contact pressure for the characterization the mechanical properties of the skin has been developed. This device, based on indentation and static friction tests, also allows to characterize the skin in vivo and reconstructed DEs in a wide range of light contact forces, stress and strain.
Results: This original bio‐tribometer shows the ability to assess the skin elasticity and friction force in a wide range of light normal load (0.5–2 g) and low contact pressure (0.5–2 kPa). The results obtained by this approach show identical values of the Young's modulus E* and the shear modulus G* of six DEs obtained from a 62‐year‐old subject (E*=8.5±1.74 kPa and G*=3.3±0.46 kPa) and in vivo total skin of 20 subjects aged 55 to 70 years (E*=8.3±2.1 kPa, G*=2.8±0.8 kpa).
The high performance of industrial applications, requires increasingly technical functional surfaces, in particular from the point of view of topography and micro texture. To study the effect of ...abrasive finishing in a wide range of wavelengths of surface topography, we developed a multi-scale approach, based on the decomposition of surface topography by 2D continuous wavelet transform. This new approach made it possible to determine the multi-scale transfer function of machining by abrasion for each stage of finishing. The methodology can be extended to characterize abrasive wear in a wide range of scales.
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