Hi! I need to detect PET bottles for my project. I'm looking for a sensor that I can connect to a microcontroller. I've seen some commercially available ones such as Omron's E3-ZB, however they are quite expensive.

I've noticed that PET sensors are photoelectric in nature, can anyone explain how they work? I would like to understand how they work and maybe I could create a simple circuit for it? Or are there other ways of sensing PET bottles? Thanks in advance!

these sensors don't detect PET specifically. They are capable of detecting transparent objects, of which PET roughly falls into.

The BIG question, is what is your background noise, or resolution. Will a homogoneous stream of materials be passing, or will one of several known items be passing? If your object is to identify if the object being placed in front of some sensor is either metalic, paper, or PET, no problem. If all are mixed together, your solution will likely include pre grading of materials, to the point that your background noise is reduced to tolerable levels.

 

How about capacitive sensors? I need to detect only PETs and sort of ignore other materials so they can pass through other sensors. I've read that capacitive sensors can be used for almost any type of material, but I dont have any idea on how to tune them specifically for PET bottles?

PS Thanks for all your replies, they are really helpful

 

Here is a company that specializes in sensors for detecting PET bottles, these sensors maybe a little on the expensive side, but it may be a good starting point for your project.... http://www.baumer.com/product-news/...ss-or-pet-bottle-detection/af34c57426/en.html

 

Thank you. Will this sensor only detect PET bottles? I've been looking into Omron's E3ZM-B (http://www.ia.omron.com/product/family/1897/index_fea.html) this past few weeks. On the other hand, I saw these videos on youtube:

http://www.youtube.com/watch?v=t0SvL-oOVU4
-> The sensor also detects the spoon.

http://www.youtube.com/watch?v=XSORbfz299M&feature=results_main&playnext=1&list=PL28EFABFB51CC37D9
-> It detects the pen

Just like what Sir GetDeviceInfo said, it looks like the sensor is optimized to be able to detect PET sensors since others can't, on the other hand the sensor can still detect other materials.
I'm scared that if I purchase this it will detect every material that will go into my conveyor belt, I won't be able to single out the bottles? Thanks!

 

Most of these sensors are NOT designed to detect PET materials in a conveyor full of other materials, they are only used in specific locations where a Known PET container may be going through, such as a filling station for automated bottlers, they use these to make sure PET bottle is in place before dispensing liquid into them.... so they can detect PET presence in a single conveyor, but they will not be able to distinguish PET from other materials....