Thanks to everyone who responded to the following question:

Does anyone has experience in elasticity and deformability of human
skin, fat and muscles, which are measured perpendicular to the body
surface? Any kind of information would be useful for me. I am specially
interested in human thighs.

Summary of the responses:

- There was a thesis work in Michigan State University by Ms. Bing Deng
on the measurement and modeling of human thigh deformation under seated
postures. In the thesis, she constructed a finite element model as
well as built a specially desgined unistructure in measuring thigh
deformations under "perpendicular to the body surface" loadings. There
is an abstract by her appeared in 1994 Annual ASME Winter Meeting
(Chicago). Check it out and good luck.

Cheng Cao
Department of Mechanical Engineering and Applied Mechanics
University of Michigan, Ann Arbor

- I don't really have any experience, but I do have some references,
and I'd love to receive a summary of responses if you write one. Here
are my references:

Alexander H., Miller D.L. (1979) Determining skin thickness with pulsed
ultrasound. The Journal of
Investigative Dermatology 72: 17-19.

Bader D.L., Bowker P. (1983) Mechanical characteristics of skin and
underlying tissues in vivo.
Biomaterials 4: 305-308.

Daly C.H. (1982) Biomechanical properties of dermis.Journal of
Investigative Dermatology 79:
Supplement 1, 17-20.

Hickman K.E., Lindan O., Reswick J.B., Scanlan R.H. (1966) Deformation
and flow in compressed skin
tissues. Proceedings of the Biomedical Fluid Mechanics Symposium
(A.S.M.E.) 127-147.

Kirsch K.A., Merke J., Rambo N., Wicke H.J. (1980) Tissue compliance in
superficial tissues along
body axis in man. Pflugers Archives 387: 239-244.

Tregear R.T., Dirnhuber P. (1965) Viscous flow in compressed human and
rat skin. Journal of
Investigative Dermatology 45: 119-125.

Salathe EP Jr. Arangio GA. Salathe EP. The foot as a shock absorber.
Journal of Biomechanics.
23(7):655-9, 1990.

Brozek J, Kinzey W (1960) Age changes in skinfold compressibility.
Journal of Gerontology 15 (1):

Himes JH, Roche AF, Siervogel RM (1979) Compressibility of skinfolds
and the measurement of
subcutaneous fatness. American Journal of Clinical Nutrition 32:

Kirk JE, Chieffi M (1962) Variation with age in elasticity of skin and
subcutaneous tissue in human
individuals. Journal of Gerontology 17: 373-380.

Barbenel JC, Evans JH, Finlay JB (1973) Stress-strain-time relations
for soft connective tissues,
in Kenedi RM (Ed) Perspectives in Biomedical Engineering, The Macmillan
Press, London, pp. 165-172.

Payne PA (1991) Measurement of properties and function of skin.
Clinical Physics and Physiological
Measurement 12: 105-129.

Clegg EJ, Kent C (1967) Skinfold compressibility in young adults. Human
Biology 4: 418-429.

Becque MD, Katch VL, Moffatt RJ (1986) Time course of skin-plus-fat
compression in males and
females. Human Biology 58: 33-42.

Gerritsen KGM, van den Bogert AJ, Nigg BM (1995) Direct dynamics
simulation of the impact phase in
heel-toe running. Journal of Biomechanics 28: 661-668.

Sakai F. Ebihara S. Akiyama M. Horikawa M. Pericranial muscle
hardness in tension-type headache.
A non-invasive measurement method and its clinical application. Brain.
118 ( Pt 2):523-31, 1995.



Michael Lee
Department of Biomedical Sciences
University of Sydney, Australia

- Many people have conducted indentation testing of residual soft
tissues (at the shank as well as at the thigh), both in-vivo as in
cadavers, to assess pseudo Elastic Modulus. Indentations have been
done manually or conmputer driven. I will give you names which you
could search for: JW Steege, R Torres-Moreno, M Lord, DR Reynolds, M
Malinauskas, YC Fung, RM Kenedi, EM Krokosky, CH Daly, H Alexander, T
PFF Wijn, L Sokoloff, KC Chung, TA Krouskop, B Silver-Thorn, Sacks,
Russell, DR Veronda and RA Westmann.

With kind regards,

Ricardo Torres-Moreno, Ph.D., Bioengineering
Assistant Professor, School of Physical and
Occupational Therapy, McGill University
3630 Drummond Street, Montreal, Quebec, CANADA H3G 1Y5

Phone : (514) 398-4521
Fax : (514) 398-8193

- I did some work on my Ph.D. of doing a 1-D compression test of the
human buttocks tissues with a probe of about a half-inch diameter as
I recall. The work related to wheelchair seating, and I needed some
type of material properties to input into a finite element model.
I'll send you some more information if you're interested.

Beth Todd

Dr. Beth A. Todd
Assistant Professor
Engineering Science and Mechanics
Box 870278
University of Alabama
Tuscaloosa, AL 35487-0278
fax: (205)348-7240

-The following paper:

J. Ophir, I. Cespedes, H. Ponnekanti, Y. Yazdi & X. Li
Elastography: a quantitative method for imaging the elasticity of
biological tissues. Ultrasonic Imaging 13, 1991,pp 111-134

describes a method for quantitative elsticity measurements based on
ultrasound. I know these authors have issued later papers on the same
subject. Maybe you can find the figures youare asking for there.
Otherwise you might have to measure it yourself - the paper indicates

I hope this helps - good luck!

Best regards,

We have some data on the displacement of a few skin markers relative to
the bone for one subject. Bone markers were mounted on skeletal pins.

Mike Murphy

- You must check out the classic paper by Lanir and Fung on the 2-D
of skin. Yes, it deals primarily with circumferential strains and not
normal strains like you want, but it's the place to start if you want
understand the mechanics of skin.

For a good text on indentation tests, see Contact mechanics by Johnson.
is a good discussion of the normal and shear forces at the interface of

good luck!

Alexander Schmidt

Neenah, WI (USA)
Tel.: 414-721-6481, Fax.: 414-721-5459