Written by: Bjoern Schaefer
Capacitive sensors certainly serve a niche within the group of proximity sensors. This niche makes people overlook the most striking feature this technology provides us – remote detection of any liquid through glass or plastic walls. On the first look that does not sound too exciting and I agree, as long as you have not been tasked to specify a sensor to accomplish this very job.
Capacitive sensors serve a simple, but powerful purpose in these applications. A medical OEM, who needs to check the level of frequently changing liquid compositions of its chemical reagents, doesn’t have many options to fall back on. Tasked to simple monitor a level inside a disposable plastic container, while avoiding cross contamination, one has to consider liquid level measurement by volume flow (expensive), by weight (expensive and difficult to calibrate), by visual inspection (too cheap of a solution for expensive and high – tech machinery), or capacitive ( inexpensive and robust).
You could say that I am biased, and that might be true, but I have seen far too many overcomplicated attempts to solve this simple problem in the past.