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Evolution in impedance at the electrode-skin interface of two types of surface EMG electrodes during long-term recordings

  • David Hewson
    ,
  • Jean-Yves Hogrel
    ,
  • Yves Langeron
    ,
  • Jacques Duchêne
  • Université de technologie de Troyes
Research Output: Contribution to journal Article Peer-review

Abstract

The evolution in impedance at the electrode-skin interface of Beckman and Red Dot electrodes was assessed during long-term recordings. Impedance was measured between each pair of electrodes, arranged in a bipolar configuration on tibialis anterior (n=13). A waveform constructed of sinusoids of known frequencies, evenly distributed on a log scale from 1–16,384 Hz, was applied through the electrodes, and the result recorded by a DAQ system. SEMG signals were recorded at 1000 Hz during isometric dorsiflexion contractions of 30 s, performed every 15 min for 2 h. Impedance data were acquired at 65,536 Hz immediately before and after SEMG recordings. Large individual differences in impedance levels were observed at low frequencies. At high frequencies, impedance values depended only on the electrode type. Impedance decreased steadily with time for Beckman electrodes (p < 0.05), but did not decrease significantly for Red Dot electrodes. The magnitude of the reduction over time varied widely between individuals, and was related to the initial impedance values. The impedance-bandwidth product remained constant for each electrode type (95% confidence intervals 146.2–148.2 and 126.1–127.8 for Beckman and Red Dot electrodes respectively). When skin impedance is electrically modelled with a simple network containing a resistor and a capacitor, the capacitance varies with the properties of the electrode used, whereas resistance is dependent on the subject. Furthermore, the EMG spectrum is unaffected by impedance provided skin preparation is sufficient to reduce the impedance below 55 kΩ.

Publication Information

Output type

Research Output: Contribution to journal Article Peer-review

Original language

English

Pages from-to (Number of pages)

Pages 273-279

Journal (Volume, Issue Number)

Journal of Electromyography and Kinesiology (Volume 13, Issue 3)

Publication milestones

  • Accepted/In press - 18/10/2002
  • Published - 30/06/2003

Publication status

Published - 30/06/2003

ISSN

1050-6411

External Publication IDs

  • handle.net: 10547/623460
  • Scopus: 0037410155

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