How are similar electrodes rated?

Expert Advice:   EEG Signals     Impedances

                              Disinfect Electrodes       Pediatric Leads

How are similar electrodes rated? Is one "better" than another? More stable for instance?

Electrodes don’t have a current rating system because the decision of which electrode depends on budget, patient demographics, and, most of all, a simple issue of personal preference in most situations.

If you compare electrodes, you have a few differences, such as different types of metal. Electrode options include gold, silver or silver/chloride, tin, platinum and more. Now these metal types are often just on the outside of the electrodes--for example a Gold Cup is typically an electrode made of silver with a plating of gold on top of the silver base. Many folks think a gold electrode is 100% gold and this is not the case. The purpose of the metal is to conduct, and each lab may decide which metal produces the best data for their service. Gold is usually preferred for PSG because it has been shown to enhance the slower frequencies better which is important for PSG labs. EEG and Epilepsy labs have a preference for silver metals because they accentuate the faster frequencies. I will admit that I have used many different types of metals and I have difficulty telling the difference in data results.

Beyond the metal, there are differences in the way the “cup” shape is made. A “stamped” style electrode typically has a bigger cup capacity and is a thinner thickness versus the “casted” style which is a thicker metal cup with a smaller cup capacity in some cases. Both collect data and it’s a preference as to which is preferred.Some casted styles have a thinner “rim” that touches the patient than a stamped, so some folks prefer a casted for skin integrity issues.

Other differences are the way lead wires are made. Some are made of copper, some of tinsel and other materials. That is what makes different lead wires “feel” different between manufacturers. Different strategies are used due to cost and artifact management.

And, then you have the transition to the use of fully disposable EEG electrodes which are electrodes made of a base of plastic and covered by silver, silver/silver chloride, or other materials.

So, the summary to the above answer is that is up to each individual as data can support the advantages of each different type of lead, but whether that benefit translates to a usable benefit for your lab is a question only you can answer. To compare, I would recommend calling manufacturers and asking for samples for comparison purposes and do your own head to head comparison. Because remember, you can use different leads from different manufacturers, however, I would avoid mixing metals on the same patient or differing types of conductive paste. But, the same metal type with the same past or gel will be a solid comparison.