In recent years a number of privacy advocates have been trying to draw attention to a new technology — RFID chips. Basically, RFID chips are a simple circuit which emit a unique signal when a reader is within range — for most not more than a few feet. The chips are small, lightweight, waterproof, and require no external power source.

Similar chips are used in identification badges at some schools to access buildings, and in the DC Metro’s SmartTrip cards. Retailers have been using the technology to replace bar codes and prevent theft by embedding the chips in CDs and other products. Wal-Mart has drawn attention by pressuring its suppliers to use the chips in products. The technology has been such a hit there’s even an RFID Journal. However, the people at EFF and the authors of the books SpyChips fear the chips will allow individuals to be tracked anywhere in the world.

While I don’t share the opinion of some of the technology’s more shrill critics, I was mildly surprised to find a chip directly sewn into clothing at a Gap store. I am not sure what they were used for — if it was theft prevention I am not sure how the chip would “know” it had been deactivated as it is a “dumb” chip that only emits its unique code.

To the left are several pictures of the chip as I found it in a knit hat, shown with light shining through it, and after I had been able to peel off one side of its fabric covering. There are bigger versions on Flickr.

This article has a good summary of RFID technology.