Electrode Properties – gel and adhesive

  • Dec, 15, 2006

SALT CONTENT

Disposable Electrode
 Chloride %
EL500
10%
EL501
10%
EL502
4% (solid gel)
EL503
7%
EL504
4% (solid gel)
EL507
 0.5%
EL508
10%
EL509
n/a: dry electrodeā€”use your own choice of gel

For electrical stimulation, generally, the lower the electrode salt content, the less skin irritationĀ the subject will experience; this is because fewer salt ions are driven into skin during stimulation. This strategy puts more demand on the stimulator, because skin impedances are higher with low salt electrodes. There is no one size fits all requirement. For example, it’s possible to help mitigate the undesirable effects of higher salt content electrodes by stimulating the subject with bipolar pulses, instead of unipolar pulses.

SOLID

The salt content in all SOLID gel electrodes from BIOPACĀ is 4%. This universal gel can be used short and long term, and is suitable for adult and infants.

SOLID gels are gentler on the skin than WET gels at the same saltĀ  concentration. This is due to the higher water content in the WET gels that make them react fasterĀ  and more aggressively on the skin.

  • If there areĀ two (2)Ā electrodes with 4% salt , one (1) WETĀ gel and one (1) SOLID gel, the WETĀ gel would be more reactive/aggressive.

WET

The salt content in WET gel electrodes from BIOPAC varies:
  • 10% is used for short term applications such as Resting ECG or Stress Test.
  • 7% is a more universal gel and can be used for short andā€”for most subjects, though some reactā€”long term
  • 3% is a monitoring gel used for more than 24 hours.
  • 1% is a sensitive skin gel, common (infants/elders).
  • 0.5% in EDA/GSR electrodes.

DURATION

We do not recommend for applications running more than 24 hours.

IRRITATION FACTORS

Possible skin irritationĀ canĀ result fromĀ the gel or the adhesive on the body of the electrode.
  • EL503 gel and adhesive are aggressive
  • EL502Ā uses a non-aggressive gel (solid gels are always less aggressive than wet gels with similar salt concentrations) with an aggressive adhesive.

Noteā€”About 2 % of the population will react to any adhesives and gels put on a skin, regardless of composition or concentration.