Radio-frequency identification (RFID) tags have become commonplace because they allow for cheap and easy tracking on all kinds of objects. However, even the thinnest versions of these tags have remained too thick for embedding in materials like paper, and usually don’t respond well to being bent.Engineers at the North Dakota State University have solved that problem, though, by developing a new way of manufacturing the tags allowing them to be much thinner. So thin, in fact, they can be embedded in a sheet of paper without leaving a noticeable bump.The key to super thin RFID tags is the use of Laser Enabled Advanced Packaging, which uses a low-cost laser to join the RFID chip and antenna with a substrate. The silicon chip embedded is only 20 microns thick, so you can’t see or even feel it embedded in the paper. Another positive side effect of this manufacturing process is that silicon at this thickness becomes flexible, meaning you can bend and fold the paper without the RFID chip breaking.The same method can also be used to embed the RFID tag in a sheet of metal. However, the research team have come up with a way of removing the need for the antenna by using the metal the chip is embedded in as a replacement.Such a manufacturing breakthrough means that RFID tracking can be added to paper products such as banknotes, legal documents, or even tickets in a bid to stop counterfeiting. The fact their presence is completely hidden means you wont even know they are there. As for embedding them in metal, it could open up a few new silent security options for the consumer. For example, how about having an RFID tags embedded in your laptop so it can easily be identified if stolen while remaining impossible to remove?