most advanced Ambu® BlueSensor ECG Electrodes or Vermed

but most used : DMS , Boenmed

Dry electrode is a nonsense.

First, try to measure ECG signal with normal electrodes!

To Elgharabawy,

Thank you so much:) I'll check these electrodes you mentioned.

As Mr. Dobrev say dry electrode is a nonsense. Could you tell me your  understanding about the difference between dry electrodes and wet electrodes?

Thanks so much

Henry Zhang

 To Dr. Dobrev,

Thank you so much for such a firmly viewpoint.

Actually, I have measured the ECG with the normal wet electrodes, I'd like to know some new information about the dry one. 

Could you please give me some advice about dry electrodes? Why they are nonsense and what is the signal you detect by them?

So many thanks.

Henry Zhang

Biopotentials are generated in the body. They are registered by a charge transfer over the finite impedance of the bioamplifier, producing voltage at the amplifier input.  Electrode purpose is to make interface for this charge, easy to reach the amplifier. The charge must travel from ion conducting medium, in the body, to electron conducting medium, in the electrode cables.

Electrode gel is an electrolyte. It makes low ohmic connection between skin surface and the cable, and is well conducting medium for the charge. This low ohmic connection, has low ohmic impedance, if expressed with capacitor impedance 1/wC, it has infinite capacitance C!

Dry electrode has dielectric, instead electrolyte. It behaves like a capacitor, small capacitor is series to the amplifier input. It is a source of artifacts and differentiates (distorts) the useful signal.

Advice?

Use electrode gel :)

ok, if you want to experiment, you should increase as much as possible the electrode capacitance, i.e. the electrode area - it should be > 1 sq. dm (decimeter), like electrodes for defibrillation, and also the amplifier input impedance.

Even in that case, you should have at least one wet reference electrode for the ground to set the body potential inside the common mode input range of the amplifier. 

Silver silver chloride ,use and throw electrodes are commercially available.

Hi Huanqian

There was a company giving samples a few years ago. You can refer to my sensors paper to get their name. Good luck.

 To Dr, Dobrev, 

Thank you so much for such a detail and careful explanation:) All of them are very useful! Especially for the bio-medical part.

However, I have seen many research on the field of dry electrodes. Maybe I'll have a try. Your advice will be very useful in my future research.

Best Regard:)

To Dr. Mahalingam,

Thank you so much for your information:) I have used Silver silver chloride before. The same as you mentioned, their function are very well.

Hi Buxi,

I'll check it again. Thank you so much and have a nice day:)