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Seems like I’ve seen moisture sensors using capacitive sensing, which is maybe what you mean by the RC oscillator. I probably wouldn’t want to pass actual current from positive to ground through the water if that’s what you’re proposing (Maybe it would work, and maybe that is an accepted technique, but just my gut feeling).
For more info on capacitive sensing, you might check out this article I wrote some time ago about ATtiny touch sensing: https://embeddedcomputing.com/technology/software-and-os/ides-application-programming/attiny85-capacitive-touch-sensing-sans-external-resistors – The other thing that could be very useful shapes-wise IIRC is this Microchip capacitve Touch Sensor Guide (referenced there): https://ww1.microchip.com/downloads/aemDocuments/documents/TXFG/ApplicationNotes/ApplicationNotes/Capacitive-Touch-Sensor-Design-Guide-DS00002934-B.pdf – Has been a while since I looked at it, but lots of great info IIRC.
Thanks for the suggestion! Capacitive sensing is exactly what I had in mind. I’ll take a look at your article and the Microchip guide you mentioned. those sound really helpful. I was thinking about using interdigitated electrodes to improve sensitivity. do you think that’s a good choice for this? Also, I’ve been considering an RC oscillator circuit for the detection, but I’m open to better ideas if you have any thoughts on that!
Glad I could (hopefully) help. I’m not sure what interdigitated electrodes are, so I have no input there. Oscillator may work well, but you could also look at doing the operation in firmware via a microcontroller.
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