Hi, I'm new at arduino. I would like to know if there are sensors that detect the type of material, for example if it is plastic, metal, paper or something else.
Yes, there is. It's called "human beeing". Has some actuators, too, so it can easily be interfaced with an arduino.
If the search functionality of this forum had any use, I would tell you to use it as this kind of problem pops up ever second week.
Sensors detect phyiscal properties of objects, like colors, resistance etc. The conclusion which material may have the reported properties is up to the user. Not so easy for a compound object...