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Topic: Is it safe to connect Arduino to human body? (Read 6833 times) previous topic - next topic

raschemmel

#30
Jul 21, 2015, 12:43 am Last Edit: Jul 21, 2015, 12:48 am by raschemmel
The antistatic counter measures in an operating theater are to prevent subjecting the exposed heart muscle to a static discharge during thoracic surgery and possibly triggering ventricular fibrillation.  (I would think)
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Paul__B

#31
Jul 21, 2015, 01:48 pm Last Edit: Jul 21, 2015, 01:51 pm by Paul__B
You might think that, but you would not be correct.

The sort of "snap" that a static discharge causes would not trigger ventricular fibrillation.  And anti-static measures are neither universal nowadays, nor confined to cardio-thoracic surgery.  There is no strict connection.

Sneaky hint: You can google it!

{Aside: no more theatre for me for two weeks now! :smiley-cool: }

raschemmel

#32
Jul 21, 2015, 03:29 pm Last Edit: Jul 21, 2015, 06:04 pm by raschemmel
Quote
Sneaky hint: You can google it!  
Apparently finding the reason they use ESD in operating rooms using Google is easier said than done.

but I did find this:

Quote
CONDUCTIVE TILE FLOORING  

ESD-CONTROL TILE flooring helps control involuntary personnel movement caused by electrostatic discharge, prevent hazardous static discharge directly into patients and prevent fire or explosion where flammable anesthetics are used.
 
Modern Operational Theater

If I understand it correctly , the reasons cited are:

1- Prevent the surgeon from slashing an artery with the scalpal when his arm jerks
   involuntarily due to a static discharge.
2- Prevent a static discharge directly into the patient's chest cavity.(sounds familiar)
3- Prevent igniting the flamable anesthea gas.
4- Prevent blowing up the OR

Did I miss anything ?
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polymorph

Yes, but it has nothing to do with electrocution hazard. :smiley-lol:

(You said: "antistatic")

I did. It is because once you start getting inside the human body, or just making very good electrical contact with it, the voltages and currents required to make things go very wrong goes down considerably.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
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Paul__B

#34
Jul 22, 2015, 12:09 am Last Edit: Jul 22, 2015, 12:10 am by Paul__B
OK, so it is actually only reasons 3 and 4 - the conjectural asides in that article are entirely subsidiary to the complete paragraph on explosion risk.

Now that said, it turns out that explosion risk is actually not a common concern either - but may be in extremely rare cases.

The reason is the virtually universal use of electrosurgical diathermy where essentially the whole operation is performed not using a "cold steel" scalpel, but a diathermy "pencil" which cuts using a continuous (generally, modulated) electric arc.  Clearly this cannot be used in the presence of explosive gases (cyclopropane or ether) which not merely for this reason are almost never used.  (Such equipment, if actually present in the hospital, is carefully locked away.)

One other recent problem has been the use of alcohol-based skin preparation solutions.  These are now "outlawed" in theatre due to cases where they have failed to evaporate fully before surgery and residual pools have ignited with obvious consequences.

raschemmel

I worked in a hospital in 1971 and I don't think they had electric scalpals then.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

Paul__B

Must have been a very backwoods hospital!

The machines back then were very impressive (and large).  "Cutting" current was generated by a (thermionic) valve oscillator which was relatively silent (so an audible tone generator was used to indicate its operation).  The more frequently used "Coag" current was produced by a spark gap generator (miniature Tesla coil) and announced itself with a very characteristic "zzzzzzzzzz" sound.


Doesn't that one just look the part?

All later model devices and modern variants such as the LigaSureā„¢, VaprĀ® and (different modality) harmonic scalpel have of course, tone generators for warning of modes and fault conditions (as the electronics is totally silent).

raschemmel

Classic !

Doesn't it make you feel like you are in a SCI FI movie ?
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

Paul__B


raschemmel

#39
Jul 23, 2015, 01:05 am Last Edit: Jul 23, 2015, 01:06 am by raschemmel
Quote
Must have been a very backwoods hospital!
Not necessarily. I said:

Quote
I don't think they had electric scalpals then.
. That's probably because I was not an OR tech. The OR techs had a much longer medical training school than the Medical Service Specialists. I worked in almost every dept of the Hosp (Surgical Ward (post op), Medical Ward (internal medicine), ER, ICU, PSYCH ward,) EXCEPT surgery because only the trained OR techs were allowed to work there. Most likely they had one (because it was a USAF Hosp) and I simply didn't know it because my friends who worked in OR never mentioned it.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

Paul__B

It is clearly true that the machine is essentially only used in the Operating Theatre - because you cannot use it on a patient that is not anaesthetised (in some fashion)!

allsix


First, there is a problem with electrical safety.
Biopotential signal products all have the same electrical risk.

When you connect the Arduino to your PC, the commercial power and circuit are connected.


There are two ways to use it safely.

1. ECG -> Arduino -> Notebook (Battery mode)

2. Using ECG sensor with isolation both power and signal => PSL-iECG2

    Blog post about PSL-iECG2 & Arduino
    http://biosignalstory.blogspot.com/

TCSC47

#42
Mar 27, 2019, 02:59 pm Last Edit: Mar 27, 2019, 03:10 pm by TCSC47
I am fairly new to this forum and am so pleased and relieved that many here have said it is not safe to connect yourself to any electrical equipment via medical low resistant skin pads. There are a number of project on line that show this being done and they are all "a little bit of knowledge is a dangerous thing" and the authors are most remiss in doing it and encouraging others to do it.

I have actually designed and built an ECG measuring system professionally and the depth of hardware safe guards that have to be taken into account is significantly above that of even the competent everyday electronics designer, never mind the amateur. Then there is the bureaucracy that, quite rightly, has to be gone through to get permission to apply the equipment. And above all, you are required to have the paper trail of your components reliability as well as the copious test equipment and procedures to make sure it has all been done properly.

All this tells you it is something the amateur should not even think about.

The biggest weak link, as has been pointed out is the PC or laptop, even when operating on battery. But the same goes for the few volts available from the Arduino batteries. Once you bypass your skin resistance, you are in danger-land even from a few volts from a battery.

99.99% of the time you will get away with it. The harm only occurs when there is faulty equipment or when you attempt to measure the heart beat of some one with a heart problem. But if you have learnt one thing from your experimenting, it will be that faults DO occur. And have you ever wondered how many people around you have heart health problems? A lot.

So, don't do it.

TCSC47

#43
Mar 27, 2019, 03:07 pm Last Edit: Mar 27, 2019, 03:09 pm by TCSC47
If you want to make measurements on the Human body, use non invasive IR transparency techniques to display blood flow. Or design a system to measure power output developed on something like a cycle trainer. There are plenty of safe alternatives to make bio mechanical measurements other than  connecting someone directly to an Arduino.

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