First of all, I am in high school[to tell you that I am a newbie and lack knowledge]
What I want to achieve for now is a thing that can differentiate between poly bags[polyethylene] and other stuffs. Or a thing that could detect polyethylene.
I have to built a robot and therefore we have only a few method accessible.
Anyway any knowledge or suggestion or external links provided by you, about this topic would be welcomed by me.