Combining RFID tags with sensors

Radio frequency ID tags (RFIDs) have been in use for some time to label products for logistical purposes. Researchers have now equipped these RFID tags with sensors which allow the goods to be continuously monitored during transport. The volume of goods transported worldwide is enormous. Every day millions of tons of vehicle parts, flat screens, fresh fruit, and all manner and types of other products are carried around the world by sea, air, or road. This volume is only growing. Trouble is the journey is not always smooth or free of trouble. Car components are sometimes rusty when they arrive at the factory, and refrigerated medicines may be spoiled by the time they reach the wholesaler. In many cases, it is impossible to find the culprit or the error in the transport chain, as the goods pass through too many hands on their way around the globe. These problems will be remedied by a collaborative project called TRACK. Led by the Freiburg, Germany-based Fraunhofer Institute for Physical Measurement Techniques (IPM), six industrial companies are developing radio chips equipped with sensors for monitoring transport goods. Similar RFID tags have been in industrial use for some time for labeling individual components and products, but these tags rarely perform sensor functions in daily industrial operations, and no sturdy and affordable standard solution has yet been available. “The objective of TRACK is to develop a uniform, cost-efficient RFID chip platform with standardized interfaces to which the necessary sensors can be connected as required,” says IPM project manager Dr. Jürgen Wöllenstein. The challenge lay in developing extremely energy-efficient sensors which would save the tiny batteries in the chips. In addition, the sensor tags had to be made as flexible as a sticker.

The TRACK partners have now produced the first prototypes: Moisture sensors for monitoring car components susceptible to corrosion, and temperature sensors that watch over the refrigeration of vaccines. In the meantime, light and acceleration sensors have also been integrated to secure air freight containers. These sensors can determine whether the containers have been opened or shaken violently during transport. They continuously record measurement values which they store in the RFID chip, and an integrated clock registers the date and time of each measurement. Recipients can then read out the information conveniently by radio signal. In the event of a complaint, they can find out when and where the damage occurred, and notify the person responsible. The TRACK partners say they are confident that this combination of conventional transponders and sensors will lead to the final breakthrough of RFID technology. The first practical tests are planned for the coming year.

These RFID sensors could also be used for monitoring container security by noting minute changes in air pressure and temperature which might indicate container tamepring.