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Kevin Netto
09-08-2004, 01:52 PM
Hi All,

Thanks for the numerous replies to the query. In particular, the directive
to Winter chapter in Kumar and Mital's Electromyography in Ergonomics which
clearly states that skin-electrode impedance should be less than 1% of
amplifier impedance (in our case 10 Gohms). We are well within the limit by
simply rubbing the skin with alcohol, thus saving our poor little subjects
the strife of skin de-braiding. Here is a summary of the responses:

Kevin,
Don't pester these kids too much with skin preparation. Ensure
that the input impedance of your EMG equipment is 100 MOhm or
more, which will hold for any reasonably new apparatus, and you
need only some alcohol to clean and defat the skin.
Yours,
At Hof


Hi Kevin,

we use emg daily with older patients, sometimes the impedance reaches values
below 10 kOhm, but mostly between 10 and 20 kOhm, we try to reach at least
30 kOhm, thats a realistic valua with our setting. We prepare the skin with
a paste called "everi" from spes medica which we rub with cotton swabs.

with best regards,
Wolfhard



Hi Kevin
20 kohms may be fine depending on the input impedance of your
amplifiers i.e. should be a 1% ratio between skin/input impedance.
See Winter's chapter in Kumar and Mital "EMG and Ergonomics"
1996 Taylor and Frances Publishers.
Cheryl Kozey


Once again, thanks

Kevin Netto
NHMRC (funded) Research Officer
School of Physiotherapy, Curtin University of Technology
GPO Box U1987, WESTERN AUSTRALIA 6845
K.Netto@curtin.edu.au
http://www.physiotherapy.curtin.edu.au/home/staff/netto/

t: +61 8 9266 3681
f: +61 8 9266 3699
m: +61 0417 990 469



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