How small can an identification/authentication device be? How about 20 micrometers? That's the smallest size of the TruTag, manufactured by Cellular Bioengineering Inc. The device is designed to prevent product counterfeiting. The microtags are made of porous silica and can be safely ingested, making it possible to embed them in products such as pharmaceuticals and food. TruTags can be added to inks or varnishes, and with a melting point above 1600C they are very durable. The company says the devices could be an alternative to RFID tags in a variety of products. The devices are read by a portable spectrometer-based optical reader.