I'm in search of a highly sensitive sensor for an outdoor application. The sensor needs to be installed within a 3mm plastic pipe with a thickness of 0.5mm. Its primary task is to detect the presence of tiny ~0.1mm seeds as they flow through a liquid solution and count the total number of seeds that pass through it.
The plastic pipe used is somewhat translucent but not particularly transparent. Considering this, I'm contemplating whether an ultrasonic sensor or a light-sensitive sensor would be the most suitable choice for this task.
Could you please offer insights on which sensor type would be the best fit for this application?
Insert a narrow piece of pipe that allows only 1 grain to pass at a time. Have a liquid flow that assures some distance between the grains. Then use a light barrier to count the separated grains.
It may become a matter of fluid dynamics and sophisticated nozzles to prevent multiple grains blocking the measuring section.
Do you mean the fluid is carrying the seeds as the fluid flows or are the seeds moved by gravity? Does the fluid wet the seeds so there is no air bubble around the seed? Just trying to form a picture of your project.
0.5mm tubes on any piece of farm machinery sounds like a terrible idea.
Dirt is everywhere. If a piece of gear cannot be cleaned using a pressure washer then it will soon be unusable and on the scrap heap.
The only way I could see this working is if the seeds and liquid are prepared under clean room conditions and the delivery system is a 'use once' disposable system like an ink jet cartridge.
If you want a low tech solution, mix a know weight of seeds with a known volume of liquid so that on average you have 1 seed per ml of liquid and then you dispense that using a positive displacement pump. There are a variety of food grade gels that could be used as a carrier fluid to prevent the seeds from settling too rapidly while sitting in the tank.
You are correct; the experiment will take place in a laboratory setting. The seeds we are working with are incredibly tiny, making them nearly imperceptible to the naked eye. The primary objective of this experiment is to determine the quantity of seeds contained within a beaker.
Can you measure the resistance of one wet seed with your Ohmmeter? See if the seed conductivity will make enough difference in the water resistivity when a seed passes two electrodes.
