As I'm approaching the last few months of my PhD, what better idea than to procrastinate trying to make a level sensor?
A quick description of the setup.
In this experiment, we are measuring the level of the water in the beaker off to the right. As I couldn't be bothered to hook up a motorised sensor to move up and down, I added water into the beaker until I could detect it.
As for the sensor, I tried two methods.
1. A small coil
2. Two pieces of foil (one active, one grounded)
To measure, I used a Vector Network Analyser. This effectively measures the Impedance (how inductive/capacitive/resistive something is) from 100KHz to 20GHz.
Long and short, I'm measuring changes in the electromagnetic field from the water to air
Results
The small coil was able to detect the level when going from air to water fairly accurately within a few mms. Going from water to air, is harder to see due to the ease of seeing a peak created as opposed to destroyed.
The pieces of foil produced and interesting result somewhat highlighted by that image. The peaks would be created and destroyed (and i can reproduce these) moving up and down, depending on the level, again with few mm accuracy.
Conclusion
I appear to be able to measure the level through a glass. I also tried this with a tiny bottle of Tokaji I had lying around and could get similar results, even with a tapering neck.
The entire setup is very flimsy and noisy and with some actual effort put into it, could be made much better. Also a motorised sensor to run up and down would help greatly.
How to make your own
Co-Axial Cable ~£1
Co-axial adapters ~£2
Foil ~50p
Inductor/Coil ~20p
VNA ~£40,000 (every good household should own
at least one of these)
![Image](https://i.ibb.co/j6rwhBT/IMG-20190114-164946.jpg)