Galvanic and DC Isolation

  • #1
Ephant
135
2
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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  • #3
Medical body contact electrodes are critical.
Different levels of protection, isolation, and grounding, are needed in different situations.
 
  • #4
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.
 
  • #5
Thread paused for Moderation...
 
  • #6
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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What is galvanic isolation and why is it important?

Galvanic isolation is a technique used to prevent unwanted current flow between two parts of an electrical system, thereby avoiding corrosion and interference. It is important because it protects electronic components from voltage spikes and surges, and ensures that sensitive electronics operate without noise introduced by ground loops.

How does galvanic isolation differ from DC isolation?

Galvanic isolation separates electrical circuits by means of a physical barrier such as a transformer or optocoupler which blocks DC currents, while allowing signal or power transfer using a method that doesn't require a direct electrical connection. DC isolation specifically refers to blocking the flow of DC current between parts of a system while still allowing AC signals to pass through.

What are common methods to achieve galvanic isolation?

Common methods to achieve galvanic isolation include the use of transformers, optocouplers, and capacitive or inductive couplers. Transformers are used for isolating and transferring electrical power, optocouplers for signal transmission, and capacitive or inductive couplers for specialized applications where space and response time are critical.

What are the typical applications of galvanic isolation?

Galvanic isolation is typically used in applications where electrical systems need to be protected from potential damage due to ground potential differences, such as in medical equipment, industrial automation systems, and communication devices. It is also crucial in the integration of renewable energy sources to the power grid to ensure safety and reliability.

How does galvanic isolation affect signal integrity?

Galvanic isolation can improve signal integrity by eliminating noise caused by ground loops, voltage spikes, and other interference. However, the choice of isolation method and its implementation can affect the bandwidth and latency of the signal. For instance, transformers and optocouplers might introduce some level of signal degradation or delay, which needs to be considered in high-frequency or real-time applications.

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