Sebum and stratum corneum lipids increase human skin surface free energy as determined from contact angle measurements: A study on two anatomical sites

Mavon, Alain; Zahouani, H.; Redoulès, Daniel; Agache, P; Gall, Y.; Humbert, P

doi:10.1016/s0927-7765(96)01317-3

Cited by 112 publications

(122 citation statements)

References 27 publications

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“…The value used for the calculation of the SFE was the average of 5 individual measurements. We selected a range of SFE values to be targeted for the proposed synthetic substrates (Table 5) based on the SFE values of human skin [24,25]. The approach for calculating the SFE using the measured contact angle values is given in Appendix 2.…”

Section: Methodsmentioning

confidence: 99%

Development of a Synthetic Substrate for the in vitro Performance Testing of Sunscreens

Sohn¹,

Malburet²,

Baptiste³

et al. 2017

Skin Pharmacol Physiol

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Purpose: Polymethylmethacrylate (PMMA) plates generally used for the in vitro testing of sunscreens have failed to yield a satisfactory correlation between the sun protection factor (SPF) in vitro and that in vivo. In the present study, various polymers were investigated as alternative substrates to PMMA plates. Procedures: In total, 14 polymers were tested in terms of ultraviolet (UV) transparency by transmission spectroscopy, and surface properties by contact angle measurement. The polymers that were UV transparent and that showed surface properties similar to human skin were mold-injected in casts with various degrees of roughness to obtain corresponding substrate plates. To assess them, the in vitro SPF of 1 sunscreen was measured on a mold-injected PMMA plate as well as on the proposed polymer plates and compared to the in vivo SPF. Results: Four polymers showed a UV transmittance at 310 nm of more than 50%, as well as a total surface free energy close to the reported value for human skin. Of these, 2 provided an in vitro SPF matching the in vivo SPF contrary to the mold-injected PMMA plate for the tested oil-in-water sunscreen. Conclusion: This workdemonstrates the possibilities of using alternative polymers for synthetic substrates for in vitro sunscreen testing.

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Section: Methodsmentioning

confidence: 99%

Development of a Synthetic Substrate for the in vitro Performance Testing of Sunscreens

Sohn¹,

Malburet²,

Baptiste³

et al. 2017

Skin Pharmacol Physiol

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“…0, m ! m 0 and in this asymptotic limit, it is possible to calculate a value of ' if a reasonable value of Dg 0 is assumed, which was taken to be 35 mJ m 22 [65]. The contact area (A ridge ¼ A) of the fingerprint ridges for the normal force of 0.2 N was estimated to be 0.3 cm 2 , which leads to a contact pressure of approximately 22 kPa.…”

Section: Rsifroyalsocietypublishingorg J R Soc Interface 10: 20120467mentioning

confidence: 99%

Finger pad friction and its role in grip and touch

Adams

Johnson

Lefèvre

et al. 2013

J. R. Soc. Interface.

224

201

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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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“…Skin contains 70-80% of water (with proteinaceous structures such as collagen), 1 and such high contact angle values are rather surprising. 2 However, water droplets normally spread to much smaller contact angles when the same experiment is repeated on the same hand immediately after it is washed with soap ( Figure 1(b)); washing removes a layer of grease produced by the skin. This simple experiment implies that the state of skin is detrimental to the surface's strength of interaction with water and demonstrates a close correlation between characteristics of the surface and water spreading.…”

Section: Example One: Introduction To Wettability and Contact Anglementioning

confidence: 99%

Physics and applications of superhydrophobic and superhydrophilic surfaces and coatings

Drelich

Marmur

2014

Surface Innovations

153

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The terms superhydrophobicity and superhydrophilicity were introduced not very long ago, in 1996 and 2000, respectively.The former is used to describe exceptionally weak and the latter used to indicate strong interactions of materials and IntroductionAfter more than two centuries of research, capillarity and wetting phenomena still remain popular topics of investigation in many modern surface chemistry laboratories. Curiosity and fascination with rain droplets splashing in a puddle, water droplets decorating flowers, leaves of plants and fruits after rain or watering and colorful soap bubbles shaped at the end of wheat straw have never been stronger and go beyond scientific laboratories. Colorful images of liquid droplets and puddles, illustrating their behavior on a variety of surfaces, thrive in professional journals, popular magazines and Internet. However, terms such as wetting, spreading and contact angle are still puzzling to the layman and beginner researcher. To facilitate

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Sebum and stratum corneum lipids increase human skin surface free energy as determined from contact angle measurements: A study on two anatomical sites

Cited by 112 publications

References 27 publications

Development of a Synthetic Substrate for the in vitro Performance Testing of Sunscreens

Development of a Synthetic Substrate for the in vitro Performance Testing of Sunscreens

Finger pad friction and its role in grip and touch

Physics and applications of superhydrophobic and superhydrophilic surfaces and coatings

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