Can 9V DC Be Lethal in Biomedical Experiments?

AI Thread Summary
9V DC can be lethal, as evidenced by a case where a person testing skin resistance with a multimeter suffered a fatal heart stop due to increased current. In biomedical applications, galvanic isolation is crucial, with options like opto-isolators and ISO122 devices being discussed for safety. The ISO122 offers a digital transmission across a high-voltage barrier, potentially providing better protection than opto-isolators alone. The conversation also touches on the need for appropriate isolation methods for DC applications, especially when using battery-powered bio-amplifiers. The thread was ultimately closed due to concerns about the safety and ethics of DIY biomedical experiments without adequate expertise.
Ephant
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9V DC can kill. Did you hear the story of this person who tried using multimeter to test resistance of his skin. He tried to thin his skin then the current of the multimeter probe got bigger and stopped his heart and he got killed.

So in electrode works in the skin where it is prep by abrading it with gel, the equipment must have utmost galvanic isolation.

I'd like to inquire about the different kinds of galvanic isolation.

Some use Opto-isolator to isolate the serial or USB wires. But here the chassis is still not protected, is it?

Then you have the ISO122 where the input signal is transmitted digitally across a high-voltage differential capacitive barrier. Is this safer than just isolating the serial or USB using opto-isolator?

https://www.ti.com/lit/ds/symlink/i...49383&ref_url=https%3A%2F%2Fwww.google.com%2F

Can you also use opto-isolator to isolate the electrodes or only the ISO122, and can the ISO122 be used on the serial or USB? Does it use different chip depending on where you want to put the isolation circuit?

Also isn't there a general commercial single channel differential isolation module where you insert the 3 electrode wires (2 differential plus ground/reference/common) and it has outputs where the 3 can be connected to any bioamplifier unit? Is this possible? Perhaps the safest of all as backup to any existing isolator in the main equipment?
 
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Medical body contact electrodes are critical.
Different levels of protection, isolation, and grounding, are needed in different situations.
 
Baluncore said:
Medical body contact electrodes are critical.
Different levels of protection, isolation, and grounding, are needed in different situations.

Many galvanic protection uses protection between AC and DC and ground loops. But how about DC. Even if your bio-amplifier is just using battery. It can shock you if it gets to the input, isn't it. So what is the DC isolator commonly used? Those references are mostly to prevent AC and DC contact. But what if you are just using batteries. Remember even 9V DC can kill.
 
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Ephant said:
Did you hear the story of this person
Ephant said:
Many galvanic protection uses protection between AC and DC and ground loops. But how about DC. Even if your bio-amplifier is just using battery. It can shock you if it gets to the input, isn't it. So what is the DC isolator commonly used? Those references are mostly to prevent AC and DC contact. But what if you are just using batteries. Remember even 9V DC can kill.
After further review (and looking over your previous threads), this thread will remain closed.

I am not comfortable with you trying to use PF for advice for your DIY biomedical experiments. You do not yet have the EE and biomedical instrumentation experience to do that safely and ethically, and PF is not the place for you to try to learn those skills. Please do not post about your DIY biomedical experiments here on PF again. Thank you.
 
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