I am looking for a sensor to detect the presence (or lack thereof) of a small volume (0.1-0.4 mL) of aqueous liquid in a closed plastic (polypropylene) container. The liquid will be loaded in a specific reservoir location on a plastic cartridge, and this sensor needs to provide a yes/no answer regarding the presence or absence of liquid in this location.
The reservoir is roughly 6mm in diameter, with a 1.5mm floor thickness. The sensor would be aligned on the axis of this cylinder, on the other side of the floor, separated from the liquid by the floor and potentially a 1-2mm air gap (if a sensor can be identified that can tolerate this air gap). There are other reservoirs in this plastic cartridge that will contain liquid, that will be at least 25mm away from this reservoir.
I don't need feedback on the quantity or level of the liquid, just if there is liquid or not in this specific location. After meeting the required sensitivity to provide this feedback, my second selection criteria would be to minimize sensor size, then price.
I have been assuming this is an application for capacitive sensing, but am open to whatever gets the job done.
Thanks for your help!
