Author Topic: How to solve the “TI ADS1299 EEG demo kit is not save for humans” problem?  (Read 3265 times)

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Offline george.b

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Wait, you guys have 19V laptop batteries? ;D
 

Online KaneTW

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Indonesian Scientists that publish in Researchgate? Researchgate it is not a publication with reference or controls, it is a good place to get something a little better than the average internet garbage, but it does not guarantee any seriousness or certainly. At least use responsible and traditional sources if you're going to make any kind of claim about "scientist" work.

What are you actually expecting from this thread? Someone doing your job because you have no idea what to do?

Researchgate is an aggregator. The paper is published in the AIP conference proceedings. https://aip.scitation.org/doi/abs/10.1063/1.5139376
The relevant conference is the International Symposium of Biomedical Engineering.
« Last Edit: September 23, 2020, 01:23:25 pm by KaneTW »
 
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Offline electrolust

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I wonder how anybody survives a single session with one of these attached to them:

https://en.wikipedia.org/wiki/Electrical_muscle_stimulation

you mean with regulated, certified, fault consideration/designed devices?

i think you've missed the point of the argument.
 

Offline SilverSolder

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The power supply voltage (in this case, the laptop battery at 19V) seems a reasonable worst case voltage that is likely to appear on the pads in a worst case  fault condition, assuming you don't do anything crazy that can step that voltage up even higher.

Assuming you actually do have a technical/scientific foundation for your argument, you are failing miserably to present it in an understandable way.
And the problem is, 19V is lethal under certain fault conditions for a Type CF Applied Part (IEC 60601), which is what you have.

Let me repeat that in more blunt terms, with emphasis: YOU CAN STILL KILL SOMEONE IF YOU SCREW THIS UP BADLY ENOUGH.

Look. I do this for a living. You can not and should not under any circumstances put that eval kit on a patient. You might put it on yourself -- we have done that before. And in that case, we were literally in the same building as the nearest hospital, knew where the two nearest defibrillators were, had skilled staff monitoring the whole time (both engineers and first responders), nothing was anywhere near the heart, proper isolation was observed at all times, the person with the electrodes on volunteered themself, and we still thought it was crazy dangerous and there was no way we would ever, ever, ever ask one of our research patients to do it.

Face it. Eval kits don't go on patients. Period. End of bloody discussion.

Best to stop this nonsense now before your IRB sees any of it.

We are having a violent agreement...     19V is too much, so a battery powered laptop is not a guarantee of safety, which is the point I have been trying to make.

We are also violently agreeing that no patient / consumer should EVER be exposed to a medical electronic device that has not been designed, tested, and approved according to all relevant regulations and best practices.

With that out of the way, I don't see why the subject of medical electronics as a hobby should be banned completely from any discussion - why is it worse than making Tesla coils, huge capacitor banks, X-ray machines, microwave beams, laser cutters, or any other potentially dangerous project?  Why is it worse than driving a 700hp muscle car or riding a turbo motorcycle?  If Darwin has your number, you will have a bad day no matter what your hobby, pretty much.   

If you want to play, you have to understand the risks and know what you are doing. Personally, I did not know (until this thread) that the safe limit of current through the body can be as low as 50uA.  It has increased my respect for electricity vs biology, not decreased it...   anyone thinking of playing with this kind of stuff needs to know those limits.


« Last Edit: September 23, 2020, 02:18:25 pm by SilverSolder »
 

Online Fungus

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If Darwin has your number, you will have a bad day no matter what your hobby, pretty much.   

Stamp collecting?
 

Offline jogri

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With that out of the way, I don't see why the subject of medical electronics as a hobby should be banned completely from any discussion - why is it worse than making Tesla coils, huge capacitor banks, X-ray machines, microwave beams, laser cutters, or any other potentially dangerous project?  Why is it worse than driving a 700hp muscle car or riding a turbo motorcycle?  If Darwin has your number, you will have a bad day no matter what your hobby, pretty much.

Emphasis on the "you" part... You can stick whatever you want on your body or on your bench, but the issue here is not that the OP wants to stick it on his body, but onto unsuspecting patients that have no effing clue how dangerous it could be for them, with absolutely no regard for their safety (the title doesn't scream "I want to make this safer", it screams "I am too cheap to lend proper medical devices, how can i DIY something that was never intended to be used this way so that it might not kill some suckers")
 
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Offline SilverSolder

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If Darwin has your number, you will have a bad day no matter what your hobby, pretty much.   

Stamp collecting?

You could cut yourself with your tweezers, catch tetanus, and die!   Sitting still for hours causes a blood clot in your thigh, which dislodges an moves to your brain, causing you to die!  -  I would definitely avoid stamp collecting, it is just too dangerous!  :D
 
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Offline SilverSolder

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With that out of the way, I don't see why the subject of medical electronics as a hobby should be banned completely from any discussion - why is it worse than making Tesla coils, huge capacitor banks, X-ray machines, microwave beams, laser cutters, or any other potentially dangerous project?  Why is it worse than driving a 700hp muscle car or riding a turbo motorcycle?  If Darwin has your number, you will have a bad day no matter what your hobby, pretty much.

Emphasis on the "you" part... You can stick whatever you want on your body or on your bench, but the issue here is not that the OP wants to stick it on his body, but onto unsuspecting patients that have no effing clue how dangerous it could be for them, with absolutely no regard for their safety (the title doesn't scream "I want to make this safer", it screams "I am too cheap to lend proper medical devices, how can i DIY something that was never intended to be used this way so that it might not kill some suckers")

The original poster asked if there is a workaround to make the TI demo kit officially approved as safe for use on humans.   The short answer is NO, as has been repeated several times by most intelligent posters here -  QED!  :D

Obviously, this being the eevblog, people will want to know the details...
 

Offline joeqsmith

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With that out of the way, I don't see why the subject of medical electronics as a hobby should be banned completely from any discussion - why is it worse than making Tesla coils, huge capacitor banks, X-ray machines, microwave beams, laser cutters, or any other potentially dangerous project?  Why is it worse than driving a 700hp muscle car or riding a turbo motorcycle?  If Darwin has your number, you will have a bad day no matter what your hobby, pretty much.   
...
If you want to play, you have to understand the risks and know what you are doing.
...

I could care less if someone wants to experiment with what others may consider a high risk, as long as they are not placing anyone else at risk.   As many people have whined about me not providing details about the hand held meters I have modified, it's very rare that I would attempt to help someone in their high risk endeavors.    Maybe with the turbocharger.... 

With that, I used to get Byte magazine back in the 80s and remember an article on an EKG project.   I don't remember much about it other than I think this was my introduction to the TL084.   Someone had posted a link here for the old Byte magazines and I suspect with a little searching, someone could dig it up.   Maybe it would add something to the discussion.   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline joeqsmith

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How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Online JackJones

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Quote
When the electrodes are attached, skin contact resistance is very low: only a few hundred ohms. A leakage current of just 100 pA can be fatal.

...

A cheap method of attaining minimal isolation is to use batteries to power an instrumentation amplifier. This sounds fine in theory, but it is very risky in practice.
 

The article pretty much agrees on everything that has been said so far. It's foolish to save money on medial devices like this, especially if they're used on others.

The 284J  isolation amplifier used in the article is still available, for only $300!

https://octopart.com/284j-intronics-998777?r=sp
 

Offline SilverSolder

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June of 1979, page 49.   

https://worldradiohistory.com/Archive-Byte/70s/Byte-1979-06.pdf

Awesome article, thanks for linking.  Reminds me of some of the amateur scientist articles back in the old days, from Scientific American...  some of those projects would probably not be approved today!
 

Offline electrolust

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With that out of the way, I don't see why the subject of medical electronics as a hobby should be banned completely from any discussion

I don't see that happening here. maybe i'm misreading it.
 

Offline Someone

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Assuming you actually do have a technical/scientific foundation for your argument, you are failing miserably to present it in an understandable way.
You keep trying to chip away with "solved it no problems now, prove me wrong" addressing single minuscule points at a time, and missing the problem that solving one tiny barely relevant issue does nothing towards showing systemic safety.

There is no way you can just fix a few points here and there and say its safe, the number of possible threat vectors is huge. And the reasoning, limits, and methods are way outside your experience/knowledge. So stop posting things you think prove safety, because they are only distracting and giving a false sense of security to others.

We are intentionally avoiding presenting the ways to make it safe, as they are likely to be misquoted/misinterpreted by people unable to comprehend the nuances. Like all the "battery powered, 100% safe" rubbish where this started. If you want to learn about this area, buy the standard, buy a book about it, there are resources out there and they are both extensive, and expensive.
 

Offline SilverSolder

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[...] We are intentionally avoiding presenting the ways to make it safe [...]

I think that is the wrong attitude...  far better to teach the kids about safe sex and let them get on with it, rather than try to prevent the inevitable course of human nature...

The Byte article referenced by @joeqsmith is 41 years old, so the principles talked about therein should be fair game to talk about without anyone risking divulging trade secrets or releasing information that is not already public.
 
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Offline CatalinaWOW

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From my point of view there is quite a bit of mis-information and mis-direction in this thread.  Let me summarize what I think truth is.

1.  TI has stated their eval kit is unsafe to use on humans.   I don't believe that this actually means that it is unsafe, only that TI has not proven that it is safe.  There is a big difference between safe and certified safe.  They are making it very clear that they don't want it used as a medical device as is, and they are doing so to avoid liability issues.  You will find a disclaimer on a great many ICs stating that they are not suitable for use in medical devices for the same reason.  I doubt that they intentionally or knowingly designed it in an unsafe manner, but it is entirely possible they have overlooked one or more things.

2.  The way to work around this disclaimer is to incorporate the TI device in a medical device and go through the certification process.  I don't know how much, if any, modification would be required on the TI Eval board and it is not clear to me that there would be any advantage to this.  By the time all of the work is done to make the overall device demonstrably safe and go through the certifications it is entirely possible that the unit cost would have to be higher than existing devices.

3.  All of this hinges on medical ethics, which has become a very strange field.  My standard question for illustrating this is:  I have a pill here.  If you take it there is one chance in twenty five that you will die miserably and instantly.  But if you don't die you will live a healthy life for the next fifty years or age 85, whichever comes first.  Such a pill would never pass ethics boards, it is clearly unsafe to take.  But it would lower the death rate of a population who took it.

4.  This is further complicated here in the US and possibly in much of the western world by the legions of lawyers looking for get rich class action suits.  This field is so lucrative that forty years after a liability suit against asbestos manufacturers shut down most of this industry worldwide law firms are still finding it profitable to buy many TV ads per day on cable television looking for new plaintiffs to represent (and collect fees from).
 
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Offline Someone

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[...] We are intentionally avoiding presenting the ways to make it safe [...]

I think that is the wrong attitude...  far better to teach the kids about safe sex and let them get on with it, rather than try to prevent the inevitable course of human nature...

The Byte article referenced by @joeqsmith is 41 years old, so the principles talked about therein should be fair game to talk about without anyone risking divulging trade secrets or releasing information that is not already public.
That has been clear from the outset, want safe? Buy the already certified product rather than trying to replicate their knowledge on the cheap. You don't make your own condom or suggest glad warp is "pretty much the same thing, so it must be good enough", you just pay up for the off-the-shelf product.
 
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Offline Peter Gamma

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Many thanks for this profound discussion of my problem with the TI EEG board. I know now much more than when I asked the question :).

What about attaching the TI EEG board to a mini PC with tiny batteries, or with no batteries at all, and only solar cells?
 

Offline DrG

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What about attaching the TI EEG board to a mini PC with tiny batteries, or with no batteries at all, and only solar cells?

What about it? Be specific please. You can fill in the blank here and not let it serve as some kind of projective test.

Sixty-eight posts later, are you understanding the complexity of the issue or are you [still] looking for a step-by-step guide for "forum safety certification", which is, by the way, NOT a thing.
- Invest in science - it pays big dividends. -
 

Offline SilverSolder

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[...] We are intentionally avoiding presenting the ways to make it safe [...]

I think that is the wrong attitude...  far better to teach the kids about safe sex and let them get on with it, rather than try to prevent the inevitable course of human nature...

The Byte article referenced by @joeqsmith is 41 years old, so the principles talked about therein should be fair game to talk about without anyone risking divulging trade secrets or releasing information that is not already public.
That has been clear from the outset, want safe? Buy the already certified product rather than trying to replicate their knowledge on the cheap. You don't make your own condom or suggest glad warp is "pretty much the same thing, so it must be good enough", you just pay up for the off-the-shelf product.

The R&D efforts for a DIY condom sounds like it could be entertaining, though!  :D
 

Offline Peter Gamma

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I agree. I found that there is also a security problem with Bitalino. Bitalino Biomedical low-cost Toolkit has no answer to the question whether their products are safe for humans or not. So the discussion could also be continued in the Bitalino forum:

https://forum.bitalino.com/viewtopic.php?f=1&p=2286#p2286
 

Offline Peter Gamma

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The Indonesian researchers used the TI EEG board paired to a Rasperri PI. I also informed the reseach group who wrote the papers about the TI EEG board about the discussion here in the EEVblog, but there was no response from the research team yet. I wonder whether they used to Rasperri PI for safety reasons?

https://www.researchgate.net/publication/325635924_Design_of_EEG_Data_Acquisition_System_based_on_Raspberry_Pi_3_for_Acute_Ischemic_Stroke_Identification
 

Online Fungus

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The Indonesian researchers used the TI EEG board paired to a Rasperri PI. I wonder whether they used to Rasperri PI for safety reasons?

The real problem here is that you don't know how to answer that for yourself.

You're proposing to build a "medical" device and attach it to people but you don't know the basics.
 

Offline Peter Gamma

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In the paper, a Rasperri PI is used to aquire data from the TI EEG board and then stored on a SD card on the Rasperri PI. and then further analyzed by a MATLAB based GUI. i did not find any hints in the paper that the Rasperri PI was used for safety reasons. But does the Rasperri PI not solve the problem to prevent current to run from a PC to the TI EEG board to the EEG headseat?
 

Offline aristarchus

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@Peter Gamma

I just wonder what is your age since you keep coming back to this without understanding the basic concepts.
(no need to say your age as I do not generaly believe what people in forum posts say..)

Instead of asking this type of questions here, you should go and read the relevant accreditation freamework in your country.

If for Swiss, then
https://www.swissmedic.ch/swissmedic/en/home/medical-devices/regulation-of-medical-devices/medical-device-regulation_online-guide.html
https://www.swissmedic.ch/swissmedic/en/home/medical-devices/neue-eu-verordnungen-mdr-ivdr.html

For US
https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-assistance/overview-device-regulation

EU
https://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG%3A1993L0042%3A20071011%3Aen%3APDF
https://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG%3A1998L0079%3A20090807%3AEN%3APDF


Then decide if you gonna mark your device as for use on humans or not.
As you see, others that created similar gizmos they decided that they should not put that label on their design and inform any potential buyer with legal liability warnings.
For me, I do not endorse even that practice with liability warning, I personaly think this is fraudulent as users do not generaly read the fine print, eg you say that you give an EEG but you do not certify that it can be attached to humans, written in some page somewhere in your site..... actually this is what others do.

I guess you now understand why real medical equipment cost is high.
 


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