Simple Liquid Leak Detection - Chemical Locker

Universal Liquid Leak Detection

I'm depressed and take a little time to read and understand things. Sorry.

How would I detect just a drop or two of any liquid, be it oil, gasoline, alcohol, water, milk.... that drips out of the bottom of a cabinet thru a hole? Water i could test for conductivity.... Optical is too complex...

The greater project is a chemicals storage locker.

It's a Air Force aluminum footlocker 18x18x36". I use what i have.

It is lined on bottom with kitty litter. Lower shelf under that is angled back slightly so it wouldn't leak forward. Wet acids and petrochemicals on left, wet bases on right. Above those would be dry stuff. Stuff has to stay dry!

Also, where should I put it? Space is valuable in my single detached garage and it's a mess. I was thinking of putting a cheap roof over it and put on my patio up against my apt bldg, screwed to fence. I may install a small fan in it to keep it dry, in addition to a gas sensor such as MQ8 & 9, and DHT11 Temp and hum sensor. PPE can hang from door that swings open on little hooks along with MSDS binder, tape, bandages, light, tools.

use a camera or check manually. any sensor needs to be hit by that drop for detection, so ...

Dielectric constant of any liquid will be different from air, so some sort of capacitive sensor might be a contender.

Capacitive may work indeed. The hard part may be to get the leaked liquid to the sensor, especially if it's just a few drops and there's a lot of highly absorbent material along the way.

May make manual checking pretty hard, too.

Some may be flammable too , and that could be an issue with electrical equipment in a closed cabinet