What if barcodes disappeared from our supermarket items? Étienne Perret, a researcher in radio-frequency electronics at Grenoble INP, works on identification technologies. His work over recent years has focused on the development of RFID without electronic components, commonly known as chipless RFID. The technology aims to offer some of the advantages of classical RFID but at a similar cost to barcodes, which are more commonly used in the identification of objects. This research is very promising for use in product traceability and has earned Étienne Perret the 2020 IMT-Académie des sciences Young Scientist Prize.
Your work focuses on identification technologies: what is it exactly?
Étienne Perret: The identification technology most commonly known to the general public is the barcode. It is on every item we buy. When we go to the checkout, we know that the barcode is used to identify objects. Studies estimate that 70% of products manufactured across the world have a barcode, making it the most widely used identification technique. However, it is not the only one, there are other technologies such as RFID (radio frequency identification). It is what is used on contactless bus tickets, ski passes, entry badges for certain buildings, etc. It is a little more mysterious, it’s harder to see what’s behind it all. That said, the idea behind it is the same, regardless of the technology. The aim is to identify an item at short or medium range.
What are the current challenges surrounding these identification technologies?
EP: In lots of big companies, especially Amazon, object traceability is essential. They often need to be able to track a product from the different stages of manufacturing right through to its recycling. Each product therefore has to be able to be identified quickly. However, both of the current technologies I mentioned have limitations as well as advantages. Barcodes are inexpensive, can be printed easily but store very little information and often require human input between the scanner and the code to make sure it is read correctly. What is more, barcodes have to be visible in order to be read, which has an effect on the integrity of the product to be traced.
RFID, on the other hand, uses radio waves that pass through the material, allowing us to identify an object already packaged in a box from several meters away. However, this technology is costly. Although an RFID label only costs a few cents, it is much more expensive than a barcode. For a company that has to label millions of products a year, the difference is huge, in particular when it comes to labeling products that are worth no more than a few cents themselves.
What is the goal of your research in this context?
EP: My aim is to propose a solution in between these two technologies. At the heart of an RFID tag there is a chip that stores information, like a microprocessor. The idea I’m pursuing with my colleagues at Grenoble INP is to get rid of this chip, for economic and environmental reasons. The other advantage that we want to keep is the barcode’s ease of printing. To do so, we base our work on an unusual approach combining conductive ink and geometric labels.
How does this approach work?
EP: The idea is that each label has a unique geometric form printed in conductive ink. Its shape means that the label reflects radio frequency waves in a unique way. After that, it is a bit like a radar approach: a transmitter emits a wave, which is reflected by its environment, and the label returns the signal with a unique signature indicating its presence. Thanks to a post-processing stage, we can then recover this signature containing the information on the object.
Why is this chipless RFID technology so promising?
EP: Economically speaking, the solution would be much more advantageous than an RFID chip and could even rival the cost of a barcode. Compared to the latter, however, there are two major advantages. First of all, this technology can read through materials, like RFID. Secondly, it requires a simpler process to read the label. When you go through the supermarket checkout, the product has to be at a certain angle so that the code is facing the laser scanner. That is another problem with barcodes: a human operator is often required to carry out the identification and while it is possible to do without, it requires very expensive automated systems. Chipless RFID technology is not perfect, however, and certain limitations must be accepted, such as the reading distance, which is not the same as for conventional RFID which can reach several meters using ultra high frequency waves.
One of the other advantages of RFID is the ability to reprogram it: the information contained in an RFID tag can be changed. Is this possible with the chipless RFID technology you are developing?
EP: That is indeed one of the current research projects. In the framework of the ERC ScattererID project, we are seeking to develop the concept of rewritable chipless labels. The difficulty is obviously that we can’t use electronic components in the label. Instead, we’re basing our approach on CBRAM (conductive-bridging RAM) which is used for specific types of memories. It works by stacking three layers: metal-dielectric material-metal. Imagine a label printed locally with this type of stack. By applying a voltage to the printed pattern we can modify its properties and thus change the information contained in the label.
Does this research on chipless RFID technology have other applications than product traceability and identification?
EP: Another line of research we are looking into is using these chipless labels as sensors. We have shown that we can collect and report information on physical quantities such as temperature and humidity. For temperature, the principle is based on the ability to measure the thermal expansion of the materials that make up the label. The material “expands” by a few tens of microns. The label’s radiofrequency signature changes, and we are able detect these very subtle variations. In another field, this level of precision, obtained using radio waves, which are wireless, allows the label to be located and its movements detected. Based on this principle, we are currently also studying gestural recognition to allow us to communicate with the reader through the label’s movements.
The transfer of this technology to industry seems inevitable: where do you stand on this point?
EP: A recent project with an industrial actor led to the creation of the start-up Idyllic Technology, which aims to market chipless RFID technology to industrial firms. We expect to start presenting our innovations to companies during the course of next year. At present, it is still difficult for us to say where this technology will be used. There’s a whole economic dimension which comes into play, which will be decisive in its adoption. What I can say, though, is that I could easily see this solution being used in places where the barcode isn’t used due to its limitations, but where RFID is too expensive. There’s a place between the two, but it’s still too early to say exactly where.