Hello what's the name of the device that helps you determine the allergen for each individual?!

No such device: There is really no such device. Some unscientific practitioners would test you with something like a galvanometer and have you hold the food in your hands to test for allergy. However this is only measuring electrical current from different foods having nothing to do with allergy. In fact, everyone would likely be test-positive for the same food although in varying degrees.