How to Detect Gases Using a Shoe Box!

As technology advances — with better batteries, more powerful processors and bigger memory — technologists are constantly striving towards the next big think. And one group of researchers are thinking outside the box by looking at technology that could help save lives — using simple technology found in every box of shoes.

Introducing RFIDs

First a bit of technology — RFID stands for radio frequency identification, and is simply a tag or label that can identify an object. You have probably seen them when you have bought something from a shop that comes in a box — that small object, approximately one inch square, that looks like a small circuit between two pieces of paper is an RFID.

RFID is similar to a barcode in that it can store information — except that unlike a barcode it uses radio waves and doesn’t need to be seen to read its data. When you walk through the barriers at the front of a shop and the alarm goes off — it is because the RFID hasn’t been turned off or disarmed.

At its most simple, an RFID is basically a circuit, with an antenna, in a protective coating. They can be as small as a grain of rice and do not need a battery. Passive RFID tags, the most common type, “wake up” when they receive a signal from an RFID reader in the form of radio waves. The radio waves provide the power for the tag to transmit a return signal of the information stored in the tag to the reader. In distribution systems for example, this could be the product type and sales destination, so allowing an automated system to deliver the box to the right location.

Researchers at the Massachusetts Institute of Technology (MIT) have taken a specific frequency range of the RFID spectrum used for NFC (near field communication) and developed some pretty amazing tags.

Barcode Gas Detectors

The team have developed tags that can detect gases — with the new sensors described in the Proceedings of the National Academy of Sciences. Professor Timothy Swager, one of the lead authors, states in a press release that “You can get quite imaginative as to what you might want to do with a technology like this.”

The team demonstrated they can make sensors to detect gases such as ammonia: but sensors could be made to detect many other gases from explosives (topics of importance for many workers as discussed in this article: Reducing Risks and the Cost of Gas Detection) to contaminated food. The team modified tags by removing part of the circuit and inserting in the gap a link made of carbon nanotubes made to detect a specific gas. When gas molecules bind to the nanotubes, the resistance to current flow changes, and this can be detected from the tag’s output signal.

The technology is inexpensive and with most new smartphones already having the capability to use NFC — you might soon be using your phone to check just how fresh the steak you’re buying really is.