View Full Version : collagen fiber deformations

Dr. Michael S. Sacks
09-05-1995, 01:17 PM
A few months ago I posted the following message:

J. Michael Lee recently mailed to me the following interesting
A couple of years ago we were very interested in whether displacement of
markers attached to the surface of tissue samples gave accurate reflections of
internal deformations. We made a micro-tensile tester similar to that
described in the 70's by Neil Broom and used it to deform uniaxial samples of
canine pericardium---a tissue which is nearly transparent. This device was
mounted on a microscope so we could follow internal structure using
birefringence microscopy. We placed small graphite particles on the tissue
surface, or glued on small metal flakes. What we discovered was that the
tissue surface (at least in simple tensile tests) often deforms by quite
different amounts than does the internal structure. We were very concerned
about this as you can imagine. I would urge anyone relying on this type of
system to develop appropriate control experiments to confirm the relationship
between internal/surface deformation.

I would like to start a discussion on this topic of inter-laminar
collagen fiber mobility when the tissue is stretched. This result
could potentially affect much of the biomechanical data collection
techniques that have been used for decades for soft tissues. Please
feel free to respond freely with your ideas. As usual, I will attempt
to put together all the responses into a single file when I feel we
have exhausted the subject.

As luck would have it, I ran out of time to really moderate this
discussion. I would like to have another go at it. Please post
your thoughts on this topic or any other related to the micro-
mechanical basis of soft tissue mechanical behavior.

Best regards,

Michael Sacks, Ph.D.
Dept. of Biomedical Eng.
U. Miami