RFID tags for wireless electrochemical detection of volatile chemicals

This work outlines a new approach for the construction of a wireless and battery-free broad response vapour sensor. Carbon black/organic polymer composites are known to swell reversibly upon exposure to volatile chemicals. We integrated these types of composites into the electronic elements of a conventional passive RFID tag circuitry to produce resistance changes that result in a change in the RFID tag's output signal frequency and amplitude. To identify vapours, arrays of RFID tags with such vapour-sensing elements were constructed, with each tag containing carbon black as the conducting element and a polymer as the sensing element. The different gas-solid partition coefficients for the polymers in the sensor array produce a unique pattern of signal changes that can be used to classify vapours. This sensor array was able to identify and quantify several vapours of interest (water, ammonia, ethanol and toluene). (C) 2013 Elsevier B.V. All rights reserved.