The world's smallest and thinnest RFID tags

The world's smallest and thinnest RFID tags were introduced yesterday by Hitachi. Tiny miracles of miniaturization, these RFID chips (Radio Frequency IDentification chips) measure just 0.05 x 0.05 millimeters.
The previous record-holder, the Hitachi mu-chip, is just 0.4 x 0.4 millimeters. Take a look at the size of the mu-chip RFID tag on a human fingertip.
(Hitachi mu-chip tiny RFID tag)
Now, compare that with the new RFID tags. The "powder type" tags are some sixty times smaller.
(Powder RFID chips next to a human hair)
The new RFID chips have a 128-bit ROM for storing a unique 38 digit number, like their predecessor. Hitachi used semiconductor miniaturization technology and electron beams to write data on the chip substrates to achieve the new, smaller size.