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Summary: Markings for strain measurement

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  • Summary: Markings for strain measurement


    I would like to thank all who replied to my original posting:

    "We are attempting to make very fine noninvasive strain measurements on
    intervertebral disc tissue. For these measurements we have being using India
    ink markings on the tissue (the fine lines need to be less than 0.1mm; if
    possible on the order of 0.05mm). However, the India ink has a tendency to
    'bleed' (even if the tissue is blotted dry), thereby distorting the very fine
    lines. We have also used non-water soluble inks but these do not adhere as well
    to the tissue.
    We are searching for a possible alternative to the India ink or ways to reduce
    the tendency of the India ink to "bleed" into the tissue."

    I think the replies can be divided into three groups:
    1) Alternative inks and stains
    2) Alternative techniques for appling the ink
    3) Alternative techniques

    The suggestions brought a fresh perspective to our project and we again thank-
    you all.

    Neil Duncan
    Orthopaedic Bioengineering Lab.
    Department of Orthopaedic Surgery
    University of California, San Francisco

    1) Alternative inks and stains



    Savio Woo uses a Verhoff stain (check with you pathology department) for
    ligament strain. There are other histo stains with should not run as much,
    which the path dept can tell you about. Check also Kai-Nan An work in J.
    Biomechanics and J Ortho Res (I forget which one) where he uses a florescent

    Another possible method for the disc might be gluing metal beads to the disc
    using crazy glue.

    Whatever methods, put on a grid of markers for 2D strain distributions.

    Best regards,
    Peter Torzilli
    Lab Soft Tissue Res
    Hospital for Special Surgery


    What do radiation oncologists mark the skin with to aim their radiation beams?
    I see patients walking around with skin markings, but don't know what they use.
    Good luck.
    Robert McAnelly



    I've worked with pericardium, and I am sceptical that any dye-based marker will
    serve your application: One needs a minimum quantity of dye for the sensors to
    pick up the marker. Have you considered some sort of chemical marking/

    The stain could be painted on with a mask.

    Santosh Zachariah

    Postdoctoral Senior Fellow
    Centre for Bioengineering, FL-20 internet:
    Univ. of Washington, ph: usa (206) 685 3488
    Seattle WA 98195 fax: 543 6124

    2) Alternative techniques for appling the ink


    I know that this might sound crazy,but have you tried using a fine tatoo needle?


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    "You are not dressed for work until you put on a smile."
    B.J. Plamer, D.C., PhC.



    Can you use a selection of points, i.e. dots of ink, to make the
    measurements, rather than lines? This may reduce the problem by reducing
    the amount of ink applied.


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    3) Alternative techniques


    I have never tried this, but could you heat-up a fine wire
    (with electric current) and burn a line into the surface?
    Perhaps one of those cheap plastic dental floss holders would help
    hold the wire. A brief, light exposure of the tissue surface
    with the hot wire may mark it without much damage to the tissue.

    John Hipp
    Beth Israel Hospital
    Orthopedic Biomechanics Lab



    I use small circular markers that I manufacture by slicing small-diameter
    plastic rods on an isomet histology saw. These markers are ~1 mm in dia.
    and ~200 microns thick (although this dimension is easily changed).

    I adhere them using cyanoacrylate (crazy clue). A *very* small amount
    is needed, and I applly it to the back of the marker using the tip of
    a pin.


    Jeff Weiss


    Dear Neil,
    There may be a variety techniques, but first a question: Are you
    measuring strain in 2D or 3D? Certainly disc bulging is a 3D phenomena.

    Trey Crisco, Ph.D.


    Dr. Duncan--
    I found your inquiry on biomch-l regarding very fine noninvasive strain
    measurements on intervertebral disc tissue very interesting.
    I, too, do noninvasive strain measurements--but on the ligaments. I
    tried the India ink technique and had the same 'bleeding' problem. Then I
    used small markers (500-800 microns in diameter) attached to the tissue.
    [We attached them with skin glue or by dipping them in hairspray and then
    placing them on the tissue. (The latter method worked just as well as the
    former.)] The problem with this method was that there was not much
    contrast between the marker and the tissue, so it was difficult to digitize
    the target positions.
    When I came here, I had to start over (without much money). I did a lot
    of reading and a lot of browsing through other people's labs and my
    students and I developed a new--and we think better--technique, based on a
    technique used in fluid flow visualization. We call this technique
    LIPPM--Laser Induced Photochemical Position Measurement. The targets are a
    small amount of either a photochromic or photoluminescent chemical which
    are mixed with a water-insoluble binder and painted or dipped into the
    tissue. These chemicals (which are available commercially) have the
    property that when excited by ultraviolet light (laser) they either change
    color (photochromic) or emit light (photoluminescent) for some short time
    (5--50 ms) after the laser light has been removed. We record target motion
    synchronously using two gated charge collecting device (CCD) cameras, each
    of which views the structures/tissues of interest from a different angle.
    We use NIH's Image 1.44 software package to digitize the two sets of
    two-dimensional data, then we use Walton's procedure to convert the two
    sets of two-dimensional data to three-dimensional data.
    The advantages to this technique are: (1) the contrast between the
    target and the tissue is tremendous and (2) the resolution is great. The
    disadvantage is that the photochemical is a very fine powder and, no matter
    how careful you are, it gets places you don't really want it to be.
    There are some equipment requirements also. First of all you need a
    laser. The laser has to be pulsed while the specimen is loaded, flexed,
    etc. If you are taking multiple views, the cameras have to be
    synchronized. You need gated CCD cameras because of the low light level
    and to get the necessary shutter opening delay between the laser pulse and
    when you film. The pulse generator driving the laser also has to be used to
    drive the cameras or the pulse generator driving the laser has to be sync'd
    to the pulse generator driving the cameras.
    I hope you find this helpful. If you have any questions, please contact me.


    Susan A. Lantz, Ph.D.
    Associate Professor
    Dept. of Mechanical Engineering
    University of Utah
    Salt Lake City, UT 84112


    Have you thought about using a Hall Effect transducer?

    Nat Ordway
    Department of Orthopedic Surgery
    SUNY Health Science Center (315) 464-6462 -->voice
    750 E. Adams St (315) 464-6470 -->fax
    Syracuse, New York 13210 -->email


    Hi Neil,

    We are working on some related issues (strain measurement in soft tissue)at
    the Biomechanics Lab at UC berkeley.

    Are you familier with the soft tissue extensometer that is made by MTS? If
    not, give me a call and I can give you some more info. Frank Ashford has my

    Good Luck,

    Ed Wachtel



    I had the same difficulty when using a video dimensional analyzer to
    measure strains in a thin fiber of collagen 50 mm long with a diameter of
    0.1 mm in a bath of 37C water. I tried several methods for applying
    strain markers that had enough contrast to generate a clean video signal
    for the VDA to latch onto, including sputtered wax, various stains and
    paints applyed with brushes, sutures, etc.

    Two methods worked very well. The first was having a vascular
    microsurgeon lay in two or three stitches of 10-0 suture across the
    specimen at 1 mm intervals (amazes me to this day...) and the second
    involved aerated water in the bath. I discovered that very small bubbles
    would form on the tissue and grip quite nicely to the surface. If they
    were lit from above in a darkened lab, an extremely sharp high contrast
    image could be clearly seen at the top edge of the bubble were the light
    reflected near the meniscus.

    The second method worked well but was discarded due to uncertainties
    about whether or not you could prove that the bubble was anchored firmly
    to the surface of the tissue or not while the surface was straining. I
    think that a mathematical proof could be worked out involving buoyancy
    forces balanced by surface tension varying with surface strain, or
    something along those lines.

    Any comments on this second method? I look forward to any discussion on
    this idea...

    - Ed -

    +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+= +=+=+=+=+

    Ed Morra
    Orthopaedic Research Laboratories
    Mt. Sinai Medical Center
    One Mt. Sinai Drive
    Cleveland, Ohio 44106
    (216) 421-4697 (vox)
    (216) 421-4843 (fax)

    +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+= +=+=+=+=+


    It seems that you are wanting do do something similar to what we
    described in:
    Stokes IAF, Greenapple DM: Measurement of surface deformation of soft
    tissue. J Biomech 18:1-7, 1985.

    Stokes IAF: Surface strain on human intervertebral discs. J Orthop Res
    5:348-355, 1987.

    Stokes IAF: Bulging of intervertebral discs: non-contacting measurements
    of anatomic specimens. J Spinal Disorders 1:189-193,1988.

    This work was done with an optical (photogrammetric) method. Two
    key things we found were:
    1. Don't use india ink, use little target markers
    2. Attach the marker by smearing the soft tissue with vaseline, don't use

    Let me know if you could use some target markers - I have a few left.
    Hope this is helpful.

    Ian Stokes
    University of Vermont, Department of Orthopaedics and Rehabil.
    Burlington, VT 05405-0084, USA
    Phone: (+1) 802 656 2250 fax: (+1) 802 656 4247



    As a suggestion, how about applying some of that spray which is used to seal
    large but superficial open wounds, and then putting ink lines on top of this? I
    am not sure how flexible the stuff is :-(

    Edsko Hekman
    Twente University
    Fac. Bio-Mechanical Engineering (WB-BW)
    Postbus 217
    7500AE Enschede
    The Netherlands


    Dear Neil,

    How about glewing thin threads on the tissue surface?




    Have you considered very fine pins or thread. These can be inserted
    into soft tissue and work well for uniaxial tests but may need more
    thoughtful placement if you are looking at biaxial strain measurement

    ************************************************** ***********************
    James Smeathers
    Rheumatology and Rehabilitation Research Unit, Leeds University, England
    Internet: RRR6JES@LEEDS.AC.UK Phone: +44-113-233-4955 Fax: +44-113-244-5533


    I am interested on your work on disc strain measurement. It is a dificult
    problem particularly on intact discs. As to your problem, have you tried
    gluing hairs onto the disc using cyanoacryate adhesive?

    Regarding the relevance of your measurements. The largest gradient in the
    compressive stress within the matrix of the disc, which corresponds (in a
    hand wavey sort of way) to the region or greatest stress in the fibres (and
    therefore perhaps strain) occurs about 2mm below the surface of the disc in
    healthy young discs - more in degenerate ones. This region would be even
    more interesting.

    Donal McNally