Too close. Barcodes are handy, but they must be read at short distances.

An e-Tag for Every Bag

Imagine being able to check out of a grocery store simply by walking through the door. That possibility is coming closer to reality thanks to a makeover engineers have given to current electronic identification tags that may allow several of them to be read at once.

Two main types of commercial identification tags are currently in use. The ubiquitous bar code is simple and costs nearly nothing to make, but it must be scanned very closely, preventing more than one item from being read at a time. On the more complex side, radio-frequency identification (RF-ID) tags are like small microchips and come in two flavors: organic and silicon. The organic chips, commonly inserted under the skin of cats and dogs in lieu of identification collars, can be made cheaply but can only process low-frequency radio waves, giving them distance limitations. Silicon chips, often used to tag bulk shipments, work at much higher frequencies and thus can be read from afar, but they're expensive to produce.

To overcome the limitations of the organic chip, engineer Soren Steudel and colleagues at IMEC research center in Leuven, Belgium, made three main modifications: They used purer organic materials, arranged these materials into thinner layers, and reduced the heat generated by the chip's operation. The improvements allowed electronic charges to move faster through the material, the researchers report online 24 July in Nature Materials. This permitted the chip to work at higher frequencies, which can be read several meters away by electronic reader.

Bob Rotzoll, senior design engineer at Organic ID Inc. in Colorado Springs, Colorado, predicts that the chips could eventually be made for about a penny a piece. If so, this could provide an easy way for retailers to survey large inventories or for security personnel to monitor the movement of dangerous items. Designing affordable tags for eager commercial customers "has been discussed in various places, but this is a clear experimental demonstration" that it is possible, says Rotzoll.

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