Help with new invention...

I have a great idea for this product that im thinking to create. But I have a few questions. I want these devices to be able to recognize each other. Say kinda like the furby's recognize other furby's. I have no idea how to do this what sensors i should use or anything. If anyone has ne idea let me know. you can email me at street.visions@Yahoo.com

#1. Never post your email address on forums. "Bots" will search it out and spam you. For your security, please go back and edit it out of your post.

#2. Forums are designed to share questions and answers with everyone, not have secret solutions emailed to you.

#3. This is a good place to ask that kind of question.

#4. I don't have a solution to your problem.

Ken