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RFID tag

I'm honestly fed up when I am standing in line for the cashier, and a person ahead of me has a basket full of items. Some stores have Express Lanes, where you can check out if you have only purchased a few items, and you can avoid having to wait too long. However, it doesn't look like a high-tech system because it is determined by the number of items purchased.

In the near future, we will not need cash to purchase things. The basket containing the items that we bought will just ride on a moving conveyer belt, the total purchase amount will be calculated and withdrawn from your bank account through your smartphone, all automatically.

In essence, it's a similar to the system of cars passing through toll gates on highways with the Electronic Toll Collection System (ETC). By applying this system to the supermarket, you can pay for your purchase without removing cash from your wallet. Everyone know that it is very convenient but the supermarket seems to have caused a huge capital investment due to the need to build a large system. I have not yet seen the system near where I shop. At present, many stores are still reading the purchased products by scanning the barcodes printed on the products one by one with a barcode reader.

One day when we went to a UNIQLO store that sells casual wear clothes, we were introduced to a system that allows us to quickly pay without having to wait in front of a cashier. What is responsible for that is high technology called an "RFID" tag. RFID tag is an abbreviation for Radio Frequency IDentifier. The plastic cards inside the paper tags are similar to those in the SUICA and ICOCA cards used for boarding trains in Japan.

(Left) Socks purchased at UNIQLO and the price tag (center.) You can see the RFID inside by looking through the price tag. (Right.) I immersed the price tag in water and removed the RFID.

The RFID taken from UNIQLO’s socks is printed on a thin film. The part indicated by the arrow is much smaller than black sesame seeds. A close-up view is shown on the right, but it seems that this is an IC (integrated circuit) with information about the product embedded in it.

(Left) RFID film (Right) Enlarged photo of IC chip

The antenna looks like a solar panel of the ISS space station, with wings spread out from the IC chip to the left and right. I think that it is made of metal, such as aluminum foil, because it is conductive when a multi-meter is applied to it.

This RFID does not always emit radio waves, including product information from a small IC attached to the center of the film. This UNIQLO RFID is a passive tag, and cannot send any information by itself. However, when it receives strong radio waves from the outside, some of the energy in the radio waves is reflected, including product information. Radio waves are being emitted.

It is such a convenient RFID tag, but it seems that the production cost of the RFID tag was the reason why it did not progress very far. Since each product contains an IC that incorporates product information, cost was a major obstacle to system construction. Recently, the unit price of the passive tags used at UNIQLO have been reduced to less than 10 cents, and we can expect expansion of the RFID systems in various stores in the future.


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