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Responses Re; TekScan equipment

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  • Responses Re; TekScan equipment

    Thank you to all who responded to my inquiry re: TekScan equipment
    The responses are included below.


    Look for a paper which Tim Eng and I presented at the Symposium on Functional
    Footwear in Tokyo last summer. You should be able to find the abstracts or
    documents through the ISB web page. There are a number of issues which you
    will account for - or at least acknowledge. But the FScan system, or the
    PEDAR system, will allow you to have greater room for the subject to move.
    Good luck.
    Jon Fewster
    NIKE Sport Research Lab

    Just a small input: The Tekscan system is resistive measuring
    The only commercially available piezoelectric technology used in
    biomechanics are our force plates.
    Best Regards
    Christian Calame

    Actually, the TekScan is not piezoelectric; Kistler force platforms use 3
    component, piezoelectric load cells that require very expensive,
    capacitance isolated cabling, and a charge amplifier for recording.
    Tekscan has patented a piezoRESISTIVE polymer ink that when used with
    photolithographic techniques, allows a relatively high spatial density of
    pressure sensitive cells to be arranged at the intersection of an
    addressable row, column matrix. Its actually the resistance of each cell
    that changes with a change in local pressure, not a change in the
    piezoelectric effect.
    The benefit of Tekscan is the pressure distribution pattern that can be
    recorded. To obtain peak force as a function of time, all non-zero cell
    magnitudes (pressures) are summed, and multiplied by a scaling factor and
    the active cell area. This is inherently less accurate than measuring
    total vertical GRF directly using a load cell, as one would do with either
    a strain gage force platform (AMTI, Bertec) or a piezoelectric force
    platform (Kistler). If you have no need for individual pressure
    distribution, you would achieve much more accurate results using any brand
    force platform; if portability is a concern, AMTI and Kistler have portable
    mounting plates for their laboratory systems.
    I've compared simultaneous recordings of Kistler and Tekscan's F-Scan
    system, and have found that if properly calibrated, Tekscan's
    non-linearities and drift can be made more manageable. Unfortunately, it
    has only been published as a conference paper:
    Carollo, J.J., Parekh, R., and Winchester, P.: Calibration and force
    correction of the F-ScanĀ foot pressure measurement system. RESNA '93; Las
    Vegas, Proceedings, June 12-17, 1993.
    If you have trouble finding it, I'd be happy to help you.
    Best Regards;

    Remember that piezoelectric sensors:
    1) Cannot perform a static measurement, because the electrical charge
    fades off in few seconds.
    2) Keramics are only sensitive in the vertical direction, but may
    have some cross-talk from other directions.
    3) It is very important to know the sensor density, cause you may
    loose signal if the dog contacts with a bony prominence on a
    non-instrumented region.

    Ruben Lafuente-Jorge
    Institute of Biomechanics of Valencia
    P.O. Box 199
    46980-Paterna (Spain)
    Tel: (96) 1366032
    Fax: (96) 1366033

    Kurt S Schulz DVM, MS
    Diplomate ACVS
    Assistant Professor, Small Animal Orthopedics
    Department of Surgical and Radiological Sciences
    2112 Tupper Hall
    University of California
    Davis, California 95616
    ph 530-752-3599
    fax 530-752-6042

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