Have any transponders been produced for this application?
Almost all automobiles manufactured since 1995 have had an RFID transponder embedded in the plastic housing surrounding their key grip. These 13.56 MHz passive transponders communicate with an RFID reader in the steering column. If a person created a duplicate of such a key that lacked the proper ID in the transponder, that individual would not be able to start the ignition. This has greatly helped to reduce vehicle theft globally.
So, yes, there are RFID transponders for car keys. If you are talking about a system that you could use to find your keys when they slip between the cushions of a couch, then I am unaware of any such home system. However, such a solution is probably only a few years away.
Motorola developed a Geiger Counter-like feature enabling a handheld reader to beep more frequently as a user gets closer to a tagged object that person is looking for; this device has been used, for instance, to track files within a real-estate office (see Real Estate Files Found With RFID). An inexpensive handheld for the home is coming soon, I'd predict.
—Mark Roberti, Founder and Editor, RFID Journal
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