I just purchased this cheap-o multimeter:
https://www.amazon.com/AstroAI-Digital-Multimeter-Voltage-Tester/dp/B01ISAMUA6/ref=sr_1_1?keywords=astroai+am33d&qid=1551837071&s=gateway&sr=8-1
I'm trying to test the resistance of my tongue by touching both probes to it (I have the red plugged into the middle port and the black into common). I start on the highest number as instructed (200M) and it gives an output of 1.1M Ohms. At 20M it fluctuates between 10M and 20M Ohms. Below that it blanks out and just says 1.
I read online that this exact procedure should give an output of 70K Ohms, the approximate resistance of the human tongue. What's up with my multimeter? Or is my tongue just insanely resistant to electricity?
Best Answer
Your body is a lossy dielectric. The ion content in the skin will reduce Resistance with skin pressure and probe metallic contact area. i.e. salt content in fluid promotes ion content.
The tip only is a very low surface area, so resistance will be >10x higher than the flat side of the probe. Pressing harder will reduce resistance.
Your body resistance is much lower than the electrode tips, which affects the results greatly.
The meter uses xxx uA to measure voltage and convert to resistance.
Dry skin 10M , 10pF hard pressure 1M 100pF
Moist skin with seat and pressure 50k ~1M 1000 pF
Tongue 10k to 1M
9V battery current: 9uA to 900uA ! ballpark.
Your mileage will vary