Friction dynamics of moisturized human skin under non‐linear motion

Sakata, Yuka; Mayama, Hiroyuki; Nonomura, Yoshiaki

doi:10.1111/ics.12751

Cited by 10 publications

(11 citation statements)

References 29 publications

(32 reference statements)

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“…Moreover, looking at the comparative friction profiles ( Figure 6 ), the friction values were higher immediately after the probe application on the skin surface and within a few seconds reached a plateau value for all tested samples (except for FFE9 formulation). This stable pattern of the friction profile [ 46 ] implies the formation of a slippery film at the skin surface and a good lubricating effect, hence suggesting a range of possible applications of emulsions based on the investigated emollients (e.g., from prospective skin care to makeup products). In general, longer plateau values indicate a longer lubricating effect of the formulation [ 28 ].…”

Section: Resultsmentioning

confidence: 99%

Efficient Development of Green Emulsifier/Emollient-Based Emulsion Vehicles: From RSM Optimal Experimental Design to Abridged In Vivo Assessment

et al. 2023

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Since natural-origin, sustainable ingredients are preferred by modern consumers, novel emulsifiers and emollients keep entering the market. This study hypothesizes that a combination of in silico, instrumental tools and simplified sensory studies could be used to efficiently characterize emulsions in a shorter timeframe. A total of 22 rather simple o/w emulsions were prepared by a time/energy-saving emulsification process. A natural mixed emulsifier (Lauryl Glucoside/Myristyl Glucoside/Polyglyceryl-6 Laurate) and two emollients (both with INCI name C15–19 Alkane) were used. The performed D-optimal experimental design within the response surface method (RSM) significantly narrowed down the number of samples about to enter the stage of texture, friction and sensory studies to the samples comprising 30% of a respective Emogreen emollient and 2% or 3% of the emulsifier. The sample comprising 2% emulsifier/30% Emogreen® L15 showed significantly higher firmness (42.12 mN) when compared to the one with 2% emulsifier/30% Emogreen® L19 (33.62 mN), which was somewhat unexpected considering the emollients’ inherent viscosity values (4.5 mPa·s for L15 and 9 mPa·s for L19). The sample with 2% emulsifier/30% Emogreen® L19 managed to maintain the lowest friction, while the one with 3% emulsifier/30% Emogreen® L19 released its full lubricating potential in the second part of the measurement (30–60 s). The obtained results revealed the strengths and weaknesses of each formulation, narrowing down their possible applications in the early development stage.

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Section: Resultsmentioning

confidence: 99%

Efficient Development of Green Emulsifier/Emollient-Based Emulsion Vehicles: From RSM Optimal Experimental Design to Abridged In Vivo Assessment

et al. 2023

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“…The probe motion speed and normal contact force of the developed sensor were determined based on the haptic exploration of a human when touching the skin. When a flexible object such as skin is rubbed at a nonconstant speed, a hysteresis originated by skin viscosity occurs [29]. This may have some influence on the evaluation of human skin.…”

Section: Discussionmentioning

confidence: 99%

Skin quality sensor to evaluate vibration and friction generated when sliding over skins

Saito,

Matsumori,

Kazama

et al. 2023

Intern J of Cosmetic Sci

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ObjectiveThe mechanical condition and tactile evaluation of skin are essential for the development of skin‐care products. Most of the existing commercial instruments and studies aim to evaluate the skin surface by pressing it for hardness or by using imaging sensors, but there have been few instrumental measurements employing rubbing motion. Here, we have developed a sensor specialized for tactile sensation and the contact phenomenon during skin rubbing.MethodsThe developed sensor has three features: it can measure body parts including cheeks and arms, automate the rubbing motion of the probe, and measure vibration and friction simultaneously. It is hand‐held, with metal probes that rub the skin surface while rotating under a motor drive; it has an accelerometer and a force sensor beneath the probe measuring vibration and friction forces. To evaluate the validity of the sensor's measurements, artificial skin models were measured using the developed sensor and commercially available sensors, and the results were compared. The relationship between the sensor output, surface roughness measurement, and sensory evaluation was also investigated. Additionally, we evaluated the inter‐rater reliability when measuring actual skin.ResultsThe measurements of five artificial skin models with different surface shapes showed a high correlation (r = 0.99) between the vibration intensity values evaluated by the developed sensor and those measured by a tri‐axial acceleration sensor attached to a fingernail. The correlation coefficient between the vibration intensity values and surface roughness was r = 0.91, and the correlation with the sensory evaluation score of roughness was r = 0.99. The friction coefficients measured by the developed sensor and the force plate had r = 0.93, based on measurements of five artificial skin models with different friction conditions. The inter‐rater correlation coefficients between the three participants of the developed sensor were as high as 0.92 and 0.94 for the vibration and friction measurements, respectively.ConclusionThe vibration intensities and friction coefficients from the sensor were highly correlated with those of the conventional sensor. The inter‐rater reliability was also high. The developed sensor can be useful for tactile evaluation in skin‐care product development.

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“…Therefore, the inter-assessor reliability of softness may be reduced by individual differences in finger size and stiffness. It is also known that finger moisture content affects friction, and that friction is associated with sensory evaluation of moistness [36][37][38][39][40][41]. Adhesion friction, which is thought to be the major force of friction when touching skin with a finger, is expressed as the product of the contact area and the shear strength of the adhesive surface.…”

Section: Discussionmentioning

confidence: 99%

Skin Sensory Assessors Highly Agree on the Appraisal of Skin Smoothness and Elasticity but Fairly on Softness and Moisturization

et al. 2022

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We tested the reliability of sensory evaluations of tactile sensation on bare skin and investigated the reliability among evaluation attributes by trained and untrained assessors. Two trained professional panelists and two untrained researchers evaluated skin in terms of several attributes: smooth–rough, elastic–not elastic, soft–hard (surface), soft–hard (base), moisturized–dry. Twenty-two women aged 25–57 years were evaluated, and the sensory evaluation was repeated twice. Correlation coefficients and intraclass correlation coefficients (ICCs) were used to examine intra- and inter-assessor reliability. The sensory evaluation and physical quantities acquired by commercial and non-commercial instruments were moderately correlated. Smooth–rough and elastic–not elastic showed high or moderate inter-assessor reliabilities with mean correlation coefficients between panelists of 0.81 and 0.58, respectively. Further, the ICC (2,1) values were 0.64 and 0.51, respectively, and the ICC (2,2) values were 0.77 and 0.67, respectively. Conversely, the reliabilities of soft–hard (surface), soft–hard (base), and moisturized–dry were low; the mean correlation coefficients between the panelists were 0.36, 0.23, and 0.22; the ICC (2,1) values were 0.27, 0.23, and 0.17; and the ICC (2,2) values were 0.42, 0.29, and 0.26, respectively. Reliability differed between attributes. We found no meaningful differences between the trained and untrained panelists regarding intra- or inter-assessor reliability.

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Friction dynamics of moisturized human skin under non‐linear motion

Cited by 10 publications

References 29 publications

Efficient Development of Green Emulsifier/Emollient-Based Emulsion Vehicles: From RSM Optimal Experimental Design to Abridged In Vivo Assessment

Efficient Development of Green Emulsifier/Emollient-Based Emulsion Vehicles: From RSM Optimal Experimental Design to Abridged In Vivo Assessment

Skin quality sensor to evaluate vibration and friction generated when sliding over skins

Skin Sensory Assessors Highly Agree on the Appraisal of Skin Smoothness and Elasticity but Fairly on Softness and Moisturization

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