Can 9V DC Be Lethal in Biomedical Experiments?

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SUMMARY

9V DC can be lethal, as demonstrated by a case where an individual testing skin resistance with a multimeter experienced a fatal heart stoppage. In biomedical applications, ensuring galvanic isolation is critical, particularly when using electrodes on the skin. Tools such as the ISO122 provide high-voltage differential capacitive barrier isolation, which is safer than basic opto-isolators. The discussion emphasizes the need for appropriate isolation techniques to prevent electrical shocks, even from battery-operated devices.

PREREQUISITES
  • Understanding of galvanic isolation techniques
  • Familiarity with ISO122 isolation technology
  • Knowledge of biomedical instrumentation safety standards
  • Experience with electrical safety in medical devices
NEXT STEPS
  • Research the specifications and applications of the ISO122 isolation chip
  • Explore the use of opto-isolators in biomedical devices
  • Investigate commercial differential isolation modules for biomedical applications
  • Study electrical safety protocols for battery-operated biomedical equipment
USEFUL FOR

Biomedical engineers, electrical engineers, safety compliance officers, and anyone involved in the design and testing of medical devices requiring electrical isolation.

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.
 
Thread paused for Moderation...
 
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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