These little piezoelectric foggers
ARE fascinating, aren't they?
However, I've mucked around with them and found that they don't work well for long periods in nutrient solutions. Through the action of the piezo element's vibration, nutrient salts will precipitate and stick to the element after a few weeks, increasing its mass to the point where it can't vibrate enough to produce fog.
They
will work for a while; you might be able to extend their life by cleaning the piezo element every week or so.
I'm wondering if the vibrating action is sufficient to separate nutrient salts from the water fog. Some clever soul will find a way to collect the fog and get it to condense in sufficient quantity so it could be measured with a nutrient meter and compared to the nutes in the solution.