Electrode high voltage protection

[moh19814]

I want to continuously measuring the ecg signal from a patient by connecting two electrodes to the chest. However, at the same time the patient is subject to receive a defibrillation shock of > 1000 volts. How to protect these electrodes against this high voltage shock, and thereby protect the ecg machine.

 

[kishore2k4]

If you are talking about professional ECG machines then they come with Isolation amplifiers with voltage withstanding capacity of several KV.

You yourself can use some of those, or you can let the analog part of ECG machine to float and isolate the digital part with optocouplers or magnetic circuits etc.

 

[dfullmer]

Hi moh19814,

kishore2k4 is correct. Use transformers and opto couplers for isolation. Many dc-dc converters will offer thousands of volts of isolation. Medical device regulations even have a class rating that says they are defibrillation rated. Type (CF).

Good luck

dfullmer

 

[mostafa_elwakeel]

you can use gas discharge tube from epcos
or component like mitsubusihi dss
thank you

 

[hakeen]

Hi,

You must use a safe insulation, rather than basic insulation. Transformer based technologies are basic insulation, and not recommended for mission critical applications like Medical.If you certify your design (e.g. acc to IEC-601) optocouplers are very good with their 5kV insulation.

I would recommend a widebody optocoupler, like HCNW series. What data rate do you carry on your dataline? There are different HCNW for different datarates. Some examples

HCNW2611 (10 MHz), HCNW136 (1MHz) from Avago....

Greetings!
Hakeen