Slashdot Mirror
Hitachi's Tiny RFID Chips
paltemalte writes "Hitachi has just come out with a new crop of RFID tags, measuring only 1/20 of a millimeter square. That's 1/8 the size (in linear dimension) of Hitachi's currently shipping mu-chips, which are 0.4 mm square. The new chip's width is slightly smaller than a human hair. These chips could put an end to shoplifting forever, but they could also be used by a governments or other entities to 'dust' crowds or areas, easily tagging anyone present without their knowledge or consent. Will someone come up with a surefire way of neutralizing chips that may be on your body or in your clothing?" Hard to pin down a source on this. The article cites another blog, which points to an article in Japanese.
Most RFID chips still have to be attached to a much larger coil antenna to make a tag that will actually work.
"Prefiero morir de pie que vivir siempre arrodillado!"
These tags are 1/20th mm square, correct? This means they are 1e-3/20 m = 5e-5m across. This corresponds to a frequency of 6 THz or for a quarter-wave antenna something like 6/4 THz = 1.5 THz. This is a very high frequency and not the easiest to make with existing technology (especially at significant power levels). This means that querying tags of this size is probably only feasible at short range using a beam that is directed at the tag as opposed to just looking in a vague region of space. Other companies have made optically addressed tags that push this direction even further but with even worse limitations. Also, at ~1 THz the attenuation due to dielectrics (or especially water) is very high and this limits the distance over which one can practically probe the chip.
Maybe my tinfoil hat is showing, but the first thing that sprang to my mind was "Great, now they have a way to track cash transactions". RFID chips in the currency, readers in the cash registers so you don't have to worry all that much about distance. They'll sell it as a way to prevent counterfeiting.