skin elasticity - mae fah luang...

Asst. Prof. Dr. Nattaya Lourith[[email protected]] 1

Skin elasticity

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Objectives

• To be acknowledged on skin elasticity• To be informed about skin elasticity

evaluation techniques• To differentiate application of each

technique

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Contents

• Introduction • Techniques in skin elasticity evaluation• Application of each technique

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• Skin => tissues + fluids components• Skin = Viscoelastic body• Skin => rheology• Skin = elasticity + viscousity

Skin

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Elasticity • Elastin : elasticity• Collagen : extensibility• Torsion extensibility sharply reduce @ 35 y

Methods

• Torsion • Suction • Wave propagation 6

Torsion = TwistometerSkin deformation with torque• Rotation sensor• Disc • Guard ring• Processor

- 4 – 57 mNm torque

- 1, 3, 5 mm skin crown

- 18 or 25 mm disc


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Torsion : Dermal torque meterExtensibility = Ue

Elasticity = Ur/Ue

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Torsion : DensiScore

Skin density

Skin creasing

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Torsion : DensiScore

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Torsion : Extensometer

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Torsion : Extensometer

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Torsion : Ballistometer

• Indentation in skin losing because of tissue viscosity

• Impact pendulum• Storage = elastic• Loss = viscous


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• Kinetic energy from falling object• Energy transfer => probe rebound

releasing• Greater rebound : elastic/viscosity

component is higher• No. of rebounds• Amplitude of the first rebound• Area of the first rebound


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Suction

• Dermalab• Cutometer 16

1. Vacuum generator

2. Probe sensor

3. Data processing

- 10 mm steel ring in probe

- 0.01 mm accuracy

- 300 or 450 mbar

- 4 or 20 s suction

- 5 or 6 cycle

Suction : Dermalab

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Suction : Cutometer

• Aperture size– 2 mm (epidermis)– 4 or 6 mm (outer layers)– 8 mm (full thickness)

• 50 and 500 mbar• Suction & relaxation time

– 0.1 – 60 s• 1 – 99 cycle

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Ue = immediate distension

Uf = final distention distension

Uv = delayed distention

Ur = immediate retraction

Suction

Uv/Ueincrease = elasticity decrease


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Parameters • Highly elasticity : Ur = Uf• R0 = Uf : passive behavior of skin to force• R1 = Uf-Ua : return to original skin state• R2 = Ua/Uf : gross elasticity =>1• R3 = last max. amplitude • R4 = last min. amplitude• R5 = Ur/Ue : net elasticity => 1• R6 = Uv/Ue : viscoelasticity => 0• R7 = Ur/Uf : skin firmness => 1• R8 = Ua : return to original skin state => 0

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ΔUr/Uf = skin firmness3 cycles, T = 22 – 24 °C, %RH = 40 – 60% (x3)

Futrakul B, Kanlayavattanakul M, Krisdaphong P. Int. J. Cosmet. Sci. 32, 211-215, 2010.

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Electrodynamometer • Skin elastic wave propagation

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• Piezoelectric elements• Acoustic shockwave

emission• Receiving depend on

elastic fibers and moisture content

• Different time wave movement interpreted in to viscoelasticity of skin

Reviscometer

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References • Edwards C, Marks R. Evaluation of biomechanical properties of

human skin. Clin. Dermatol. 13, 375-380, 1995.• Andreassi L. Bioengineering in dermatology: general aspects

and perspectives. Clin. Dermatol. 13, 289-292, 1995.• Serup J, Jemec GBE, Grove GL. Handbook of non-invasive

methods and the skin. 2nd ed. New York: CRC, 2006.• Cooper ER, Missel PJ, Hannon DP, Albright GB. Mechanical

properties of dry, normal and glycerol-treated skin as measured by the gas-bearing electrodynamometer. J. Soc. Cosmet. Chem. 36,335-348, 1985.

• Jachowicz J, McMullen R, Prettypaul D. Indentometric analysis of in vivo skin and comparison with artificial skin models. SkinRes. Technol. 13, 299-309, 2007.

• Batisse D, Bazin R, Baldeweck T. et al. Influence of age on the wrinkling capacities of skin. Skin Res. Technol. 8, 148-154, 2002.

• Petti L, Fogouang L, Uhoda I. et al. Regional variation in mottled subclinical melanoderma in the elderly. Exp. Gerontol. 38, 327-331, 2003.

Skin image & color


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Objectives

• To be acknowledged on the important of skin image and color

• To be informed on the techniques used for skin image and color analysis

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Contents

• Introduction • Techniques used in skin image• Techniques used in skin color

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Wrinkles • Crinkles

– A very fine micro-wrinkling – Disappear on stretching – @ 75 y has crinkled skin

• Glyphic wrinkles– Primary lines of normal skin surface marking– Caused by solar radiation– Appear on neck, cheek

• Linear facial wrinkles – Long, strait, slightly curve– Do not disappear on stretching 28

Glyphic wrinkles in a 65 y F

Glyphic wrinkles in a 84 y M

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Facial linear wrinkles

• Horizontal frown lines along the forehead

• Crows feet radiating from the lateral canthus of the eye

• Crease from the nose to the corners of the mouth

• Creases on the upper and lower lips radiated from the mouth

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Facial wrinkles

Horizontal lines in a 72 y M

Crows feet in a 58 y M

Creases from nose and lips in a 70 y F


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Digital photographed of skin

Index finger of different subject (row)1st row : bottom segment on palm side2nd row : finger tip3rd row : bottom segment on back side 32Ruamrak C, Lourith N, Natakankitkul S. Int. J. Cosmet.

Sci. 31, 41-46, 2009.

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Profilometry

• Skin replica of forehead (56 y M) under relaxation

• Lab conditioned @ 20 – 22 ° C, 50 –57% RH

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Profilometry

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Age

-relat

ed c

hang

es in

wrinkle

dept

h

36Age

-rel

ated

cha

nges

in w

rink

le w

idth


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Skin image analyzer

• Photography • Videography• Magnification • Different light condition• Computer program• Color analysis

– RGB– ITA° : CIELab

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Surface topography by videomicroscopy

Microscope image of skin

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Principle- Direct in vivo 3D method- Micromirror digital stripe projection system- Image on a digital matrix camera- Parameters:

. Average roughness (Ra)*

. Maximum difference (Rt)

. Average relief (Rz)

PRIMOS

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Principle- Indirect method via skin replica- Oblique lighting brings shadows from the replica to the fore - Analysis of the gray shades Parameters

: number and average depth:. microrelief furrows (<55 µm)*. average wrinkles (55-110 µm). deep wrinkles (>110 µm)

- Index:. roughness index for the skin surface relief. total wrinkled surface

Skin Image Analyser (SIA)

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Principle- Indirect method via skin replica- Laser diode scanning method- 3D image reconstitution- Parameters:

. Microrelief: complexity, average depth

. Principal wrinkles: depth, complexity and volume

Laser Profilometry

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SIAscope

visioscope

Visioscan


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Visioscan• SEr = roughness • SEsm = smoothness• SEw = wrinkles• SEsc = scaliness

44Chuarienthong P, Lourith N, Leelapornpisid P. Int. J. Cosmet. Sci. 32, 99-106, 2010.

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VISIA (RBX)

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Skin color

Epidermis : optical filterKeratinocytes : chromophore (melanin)Dermal capillaries : chromophore (haemoglobin)

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• Melanin (UV)• Haemoglobin (415, 542, 577 nm)

Skin color

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Skin color

• Colorimetry– CIELab– Hyperpigmentation decreasing L*

• Chromophore mapping• Changes in skin color tone• SIAscopy• RBX

– Melanin/haemoglobin deposition across different skin type


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• Photography – Normal light

• Hypomelanotic or hypermelanotic areas of dermis– UV light

• 300 – 400 nm (360 nm)• Epidermal change with non of dermal color change

detection– Polarized light

• Based on back-scattered light from tissue• Pigmented lesions are easily seen

• Reflectance spectroscopy• Tristimulus colorimetry

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• Shining a white light on the chosen area• Measure reflected light intensity• Reflected light at 450, 560, 600 nm• CIELa*b*

– L = relative brightness– b* = pigmentation– a* = erythema or redness

Reflectance spectroscopy

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Reflectance spectroscopy• Minolta chromameter (Minolta)• DermaSpectrophotometer (Cortex)

– 2 light emitting diodes– Green (568 nm)– Red (655 nm)

• Erythema Meter (DiaStron)• Mexameter (CK)

– 16 light emitting diodes @ 3 wavelengths– Green (568 nm) for erythema– Red (660 nm) for melanin & erythema– IR (880 nm) for melanin 52

Chromameter

Parameters. Clarity (L*). Green to red spectrum (a*). Blue to yellow spectrum (b*). ITA

Protocol design- Essay areas: forearm- Treated area and non-treated area - No photos- Repeated applications: D0-D56.

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• DHA = dihydroxyacetoneJermann R, Toumail M, Imfeld D. Development of an in

vitro efficacy test for self-tanning formulations. Int. J. Cosmet. Sci. 24, 35-42, 2002.

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Mexameter• Infrared radiation• Skin functions as a light conductor • Melanin content and erythema value• Measure under light protection

Phototype Description Melanin contentI Celtic type 0-150II Caucasian white 50-250III Mixed type 100-350IV Mediterranean type 150-500V Asian/Indian 150-650VI Black 600-999


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Mexameter

Tengamnuay P, Pengrungrungwong I, Pheansri I, Likhitwitayawuid K. Artocarpus lakoocha heartwood extract as a novel cosmetic ingredient: evaluation of the in vitro anti-tyrosinase and in vivo skin whitening activities. Int. J. Cosmet. Sci. 28, 269-276, 2006.

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Taylor hyperpigmentation scale

A series of laminated plastic cards imprinted with different color

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References • Hatzis J. The wrinkle and its measurement – a skin

surface profilometric method. Micron 35, 201-219, 2004.• Akazaki S, Imokawa G. Mechanical methods for

evaluating skin surface architecture in relation to wrinkling. J. Dermatol. Sci. 27, S5-S10, 2001.

• Callaghan TM, Wilhelm KP. A review of ageing and an examination of clinical methods in assessment of ageing skin. Part 2: clinical perspectives and clinical methods in the evaluation of ageing skin. Int. J. Cosmet. Sci., 30, 323-332, 2008.

• Taylor S, Westerhof W, Im S et al. Noninvasive techniques for the evaluation of skin color. J. Am. Acad. Dermatol. 54, S282-S290, 2006.

Skin Surface Lipid, pH and

temp.

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Objectives

• To be acknowledged on skin surface measurement

• To be familiar with skin pH and temperature determination

• To relate each parameter to skin function

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Contents

• Skin surface lipid and determination technique

• Measurement techniques of skin pH and temperature


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Surface Lipid

Surface lipid component• Epidermal lipids• SebumEpidermal lipids influence

on lipid mixture

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Surface lipid

• 10% @ 1 °C increase• circadian rhythm, high @ noon, low @

evening• provokes at puberty• reduces in elderly • 5 – 6 h refatting of forehead• 100 h refatting of scalp

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Epidermal lipids

• phopspholipids• glycosyl ceramides• ceramides• cholesterol• cholesteryl esters• fatty acids• triglycerols• hydrocarbons

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Functions

• cohesion between the skin layers• regulates the skin permeability • skin barrier @ 10.3 g/m2h TEWL• 5 – 10 to 25 – 40 μg/cm2

• Emollient • No moisturizing effect

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Sebum

• Free fatty acid ~ 30%• Triglycerides ~ 33%• Wax ~ 15%• Sterol esters ~ 5%• Squalene ~ 5%• Paraffin ~ 7%• Moisturizer independent

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Sebum secretion region

• orange peel skin

•Large pore & greasy skin

-Skin roughness

-Make-up diminishing wearability

-acne


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Sebum secretion at different age

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Extraction techniques• Solubility in organic solvents• Cylinder in known dimension contact to skin• Chromatographic analysisAbsorption techniques • Sponge wipe

– Few epidermal component• Cigarette paper

– Forehead– 4 sheets + gauze + rubber band – 3 h collection (sebum secretion rate)– Ether soke

• Bentonite clay– Larger lipids– 12 h (sebum secretion rate by glands)

Absorption/Extraction

r = 0.89

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Cigarette paper adsorption

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Determination • Sebutape

– A lipid-absorbing polymeric film or glass– 1 – 5 scale– Translucent (or reflectance chromameter : CIE)

• Lipometry– 15 s– Transmission of sapphire plate (mV)– 25 – 500 μg/cm2

• Sebumeter– Plastic film– 30 s – 0 – 500 scale

• Staining (densitometry)– Transparent plate– Unsaturated fatty acids reduce osmic acid

Lipometry/Gravimetry

r = 0.94

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Sebutape : CuDerm

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Sebutape : DualTape


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Sebutape : Sebufix

• Transparancy• 30 – 45 min collection• CIE

– L = 0 – 100 (black – white)– a = -60 - +60 (green – red)– b = -60 - +60 (blue – yellow)

• Adobe pixel scale

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Sebumeter : CK• Plastic film cartrige• 300 measurements (64 mm2)

• 0 – 350 scale

• 350 = 100% transparent

• convert to μg/cm2

• unused film calibration @ t = 0

• t = 30 s

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Correlation

• Lipometry/Sebumeter– r = 0.92

• Sebutape/Sebumeter– r = 0.53

• Sebutape image analyzer/Sebumeter– r = 0.80

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Sebum Image • Normal light

– Color photo– Bright– Shadows– Pores & blemishes

• Black light– Bacteria’s prophyrin– P. acne in sebaceous follicle

• Cross-polarized light– Color photo– Reflection reduction -> skin surface feature– Inflammatory lesion

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Fluorescent analysisWood’s lamp: UVA induces chromophores fluorescence

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Sebum-image relation parameters

• Red, green, blue : color parameters


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• Sweat = hypotonic solution; pH 4.5 – 5.5• Acidic skin provides defense against

microbe• Higher pH, more microbial growth• pH range 4.0 – 6.5• Means pH = 5.5 (1987)• Infant skin pH = 6.6 • Variation in region, sex, race, age• Male lower than Female• Axillary pH is higher than means pH

Skin pH

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• Natural skin surface pH = 4.7

• Cosmetics pH labels skin pH range of 5.4 and 5.9

• pH 8 formulation : increase TEWL

• pH 3 - 4 formulation : shedding of corneocytes from outer layer

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Skin pH

Cosmetics actions on• Solubility • Partitioning • Absorption • Penetration Towards skin

+ in vivo+ in vitro

• Sebum secretion• Sweat secretion• Skin temperature

Cosmetics efficacy particularly antiperspirant & deodorant 82

pH & temperature• Flat glass electrode• Fluorescent • Infrared • Laser Doppler

pH < 3.5 3.8 4.0 4.3 4.5 5.0 5.3 5.5 5.7 5.9 6.2 6.5 > 6.5

F acid normal high pH

M acid normal high pH

Skin pH

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References Serup J, Jemec GBE, Grove GL. Non-invasive methods and the

skin. 2nd ed. Taylor & Francis. New York, 2006.Elsner P, Merk HF, Maibach HI. Cosmetics: controlled efficacy

studies and regulation. Springer. Heidelberg, 1999.Burry J, Coulson HF, Roberts G. Circadian rhythms in axillary

skin surface pH. Int. J. Cosmet. Sci. 23, 207-210, 2001.Gfatter R, Hackl P, Braun F. Effects of soap and detergens on

skin surface pH, stratum corneum hydration and fat content in infants. Dermatol. 195, 258-262, 1997.

Wagner H, Kostka KH, Lehr CM, Schaefer UF. pH profiles in human skin: influence of two in vitro test systems for drug delivery testing. Eur. J. Pharm. Biopharm. 55, 57-65, 2003.

Lambers H, Piessens S, Bloem A et al. Natural skin surface pH is on average below 5, which is beneficial for its resident flora. Int. J. Cosmet. Sci. 28, 359-370, 2006.

Son T, Han B, Jung B, Nelson JS. Fluorescent image analysis for evaluating the condition of facial sebaceous follicles. Skin Res. Technol. 14, 201-207, 2008. 84

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