6 ms·
The pseudoscience around grounding or “earthing” is always funny because it would be trivial to measure any current flowing into or out of the patient, yet that
by PragmaticPulp 4y ago
The pseudoscience around grounding or “earthing” is always funny because it would be trivial to measure any current flowing into or out of the patient, yet that is conveniently omitted in favor of vague statements about the Earth being an “abundant source of mobile electrons”
Grounding is one of those pseudoscience topics that never seems to die because someone, somewhere will produce another study claiming dramatic positive results and the true believers will conveniently ignore any studies that don’t confirm their beliefs. Real researchers won’t touch these topics because they don’t want to be associated with such pseudoscience, so much of the published research comes from quack medicine practitioners.
- marginalia_nu 4y ago> it would be trivial to measure any current flowing into or out of the patient How would one do this, assuming the patient isn't a sphere with uniform resistance and an evenly distributed charge density?
- jfengel 4y agoClamp a meter around the lead wire.
- marginalia_nu 4y agoYeah, good point, that would do it. I was thinking of measuring current between the patient and the interface somehow. That would be a lot less trivial.
- perihelions 4y agoYou could plug two hot wires into the patient and measure their current imbalance: the difference is ground-loop leakage. That's how GFCI breakers work!
- marginalia_nu 4y agoSeems close enough to an ECG that you might end up with a fairly noisy signal.
- nomel 4y agoYou would be attempting to measure very weak, probably DC, currents. Something that could clamp on wouldn’t be sensitive enough.
- agumonkey 4y agowhat's the smallest current the average dc meter can measure ?
- nomel 4y agoWith a current clamp? Hundreds of mA. Here’s one for $600 (just the clamp) that can do 5mA. You wouldn’t use a clamp for something like this. You would use a sense resistor.
- vorpalhex 4y agoYou can easily amplify the signals in question. This is a good first circuit problem for a kid.
- nomel 4y agoNo you can’t easily amplify the signal from a current clamp. That’s why they’re never used for sensitive measurements. You wouldn’t clamp something on, you would use a sense resistor.
- vorpalhex 4y agoYou can literally buy a Fluke meter good down to 4ma with 0.2% accuracy: https://a.co/d/d8MZFKC https://a.co/d/d8MZFKC
- nomel 4y ago10mA is enough to lose control of your muscles. 4mA is incredibly insensitive [1] compared to a more direct measurement, with volts from electrons, rather than trying to measure their weak magnetic field, at a distance, as they zip by. With a sense resistor, you can use a bench top voltmeter [2] to measure nA. 1. 10fA resolution, over 400 billion times more sensitive: https://smt.at/en/products/electrometer-nv-meter/picoamperemeter-von-keithley-instruments-2/ https://smt.at/en/products/electrometer-nv-meter/picoamperem... 2. > 1 million times more sensitive, with GΩ sense resistor: https://www.keysight.com/us/en/assets/7018-06774/data-sheets/5968-0162.pdf https://www.keysight.com/us/en/assets/7018-06774/data-sheets...
- DoreenMichele 4y agoFWIW, nasal potential difference (NPD) is an existing medical test: https://cysticfibrosisnewstoday.com/cystic-fibrosis-diagnosis/nasal-potential-difference/#:~:text=A%20test%20known%20as%20nasal%20potential%20difference%2C%20or,charge%20%E2%80%94%20that%20occurs%20in%20the%20airway%20lining https://cysticfibrosisnewstoday.com/cystic-fibrosis-diagnosi....