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Andrei Chermyanin
03-13-2001, 02:58 AM
Hello

Here is a summary of the responses I received in reply to my question
(see below).

Terry O'Bannon:

Check out the Novel Pedar system at http://www.novel.de/

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Wagner de Godoy:

Try the following addresses:
http://www.rsscan.com/
http://www.tekscan.com/
http://www.novel.de/

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Jason K. Otto:

I know of two commercially available products:
F-Scan by Tekscan (www.tekscan.com). It's resistance based.
Pedar by Novel (www.novel.de). It's capacitance based.
Tekscan has better resolution, but accuracy is potentially better with
Novel. Tekscan is cheaper ($15,000?) than Novel ($25,000?).

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Jan Simon:

There are a lot of papers concerning the distribution of pressure. Look
at MedLine (http://www4.ncbi.nlm.nih.gov/PubMed/ ).

Some old ideas and methods:

1. A plate with silicon pyramids, base length 0.5cm, lying on a plate of

glass. Between the pyramids there is a couloured liquid and photographs
are taken from beneath. Evaluation of the photographs is difficult.

2. Let the subject walk over a force plate (e.g. Kistler) and don't hit
the plate with the complete foot, but with only parts of it. Very
tricky!
Scott and Winter did this 1992 in the Journal of Biomechanics and the
calculated the forces inside the foot.

3. Several sheets of paper are lying under the foot, the one direct
under
the foot is prepared with ink. The higher the pressure, the more sheets
are coloured.

4. The only real, accurate and easy way is to borrow a EMED plate from
Novel. All self made systems have to be calibrated, what is an
unpleasant
work. The same way is to collaborate with a gaitlab using such plates.
Novel offers some soles for measuring in shoes too.

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Guy Gosselin:

Why not have a look into the Pliance System from Novel (Munich), or the
Emed insole (Zurich).
Alternatively, depending on the resolution that you need, you could
create a simple piezo film sensor matrix. Have a look at at
http://www.msiusa.com/piezo/metallized_piezo_film.htm

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Alison McConnell:

Tekscan makes in-shoe pressure sensors. their sensors are reusable (and
quite dynamic) have two layers of resistive ink lines at right angles to

one another and decrease their resistance with increased force. where
the ink lines cross over is a "sensel" and the output gives you the
pressure or force at each sensel. there's some stuff in the literature
about problems with it, but i think 5% should be no prob. just make
sure
you understand their "calibration" algorithms.
Fugi-film might be another option. it is a static, one-time
measurement.
i think ink bubbles burst and colour the pad. the staining is
indicative
of the load. lots in the lit on that.

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Craig Nevin:

The best equipment is from RSscan International.
They use a sensor array with 3 or 4 sensor per square centimeter.
These EACH record at up to 500hz. The pressure plates come in a
basic 0.5m size and multiples. They are the only pressure plates that
can be coupled to forceplates to provide a real-time calibration if
accuracy is what you are after.

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Apart from BIOMCH-L list I also found:

1) Podia-Scan ( http://www.fuji-prescale.com/podiascan.html ).
This one was mentioned above by Alison McConnell as a "Fugi-film"

2) Vista Medical company (Canada)

3) AMT company (Boston, Mass., USA)

For two last items I have no web links and any details.

Thanks to all who sent a reply.

WBR,
Andrei Chermyanin, Dipl. eng.


Original question:

>Which methods are there for measurement of pressure distribution
>beneath human foot? To use a matrix of miniature load cells seems to
>me much complex and expensive because I must to provide >measurements
in a few hundreds points beneath of both foots.
>Maybe somebody know other solutions which are less expensive and >more
elegant? There is no need to measure during walking, only in static
>state, and 5% error is quite acceptable.

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