Etienne Perret

Chipless RFID tags for passive wireless sensor grids

This paper discusses the potential of some chipless RFID tags in term of sensing. Two configurations of chipless sensor tags are studied and experimented. The first configuration is based on a chipless RFID tag coded in frequency domain and transformed into a sensor thanks to a deposit of a nanomaterial that exhibits high sensitivity to humidity. One of the advantages of such a transformation is to combine both identification and sensing in the same and unique device. Very interesting sensitivity is observed in practice. The second configuration is based on the use of frequency coded tag where sensing capability consists in measuring a flight time. Then several sensors located on an object in preselected positions are used in order to monitor the deformation of the object. Interesting accuracy better than 500 μm is observed in practice. It is demonstrated that anti-collision schemes can be implemented leading to read concurrently several chipless sensor tags.

Displacement Sensor Based on Radar Cross-Polarization Measurements

This paper presents the feasibility of measuring submillimeter displacements of objects in real environments using simple resonant radar targets. These scatterers, also known as chipless tags, have their own radar signature that can be used not only for identification but also for sensing. The chipless radio frequency identification (RFID) is a highly promising technology, since it paves the way for the development of easily implementable communication systems where tags have costs similar to barcodes. Object displacements are extracted by just evaluating at different times the variation of the signals backscattered in cross polarization from the tags. Based on this analog RFID sensing principle, an analytical model is developed to perform the direct derivation of the displacements. Therefore, the approach does not require complex and specific calibration procedures based on lookup table for compensating variations due to the presence of surrounding unknown objects. It is possible to add this functionality to already designed chipless RFID tag operating in cross polarization without decreasing their coding capacity. Experimentations inside and outside anechoic chamber have been done, and a very good agreement was obtained with simulations. It has been proved that submillimeter displacements can be monitored with this approach. A chipless tag displacement of 0.5 mm with less than

Folded Multilayer C-Sections With Large Group Delay Swing for Passive Chipless RFID Applications

pm 45~mu text{m}

Toward reliable readers for chipless RFID systems

error can be detected in real environment for a read range of up to 40 cm.

Gesture recognition with the chipless RIFD technology

An origami-based multilayer structure suitable for passive chipless radio frequency identification applications is presented in this paper. Contrary to the existing multilayer designs where metallic via is used for the interconnections, the proposed technique uses the folding of the structure designed in a flexible substrate. Thus, the multilayer structure is obtained from a thin printed circuit board that is folded to give the desired 3-D structure. The proposed structure consists of cascaded commensurate transmission line sections (also known as C-sections) coupled at alternative ends. The group delay (GD) characteristic of the C-sections is utilized for encoding. Broad side coupling of the structure is exploited here, which enables large GD with higher frequency selectivity. It is proved that to produce the same amount of delay, linearly cascaded C-sections demands five times more number of C-sections than that of a multilayered structure, which also signifies the factor of miniaturization of the proposed design. A coding capacity of 6 and 12 b is estimated from the simulation, respectively, for single group and multigroup of multilayered C-sections in the allowed industrial, scientific, and medical (ISM) bands. This shows for the first time that frequency domain chipless technology can be compatible with the use of ISM bands. It also allows a coding capacity of 43 b in the ultra-wideband band which is comparable with the EAN 13 barcode.

Permittivity characterization based on Radar Cross measurements

We report in this paper several techniques to make chipless RFID systems more reliable in order to overcome some drawbacks such as detuning effects, unwanted echoes from the surrounding environment as well as the spurious interferences due to concurrent wireless systems in the ISM bands. As a figure of merit, we show through the implementation of signal processing techniques and by using optimized design that reading a chipless tag on water bottles or on a pack of metallic cans is possible and reliable. Such readings are usually not possible by using conventional designs and systems. The various techniques proposed are tested with the help of simulations, and measurements in a practical indoor environment.

RF and THz Identification Using a New Generation of Chipless RFID Tags

In this paper, we show that the chipless RFID tag can be used as a sensor to detect the presence of a user finger on the tag and also to locate the position of the finger on this tag. These results point the way toward new kind of human-computer interactions based on gesture recognition which can be contactless and 3D.

Chipless passive rfid tag

In this paper, classical radar approaches such as the ones recently introduced for chipless RFID identifications are used for nondestructive permittivity characterization of a large variety of materials. A metallic resonant scatterer is placed on the material to be characterized and thanks to the acquisition of its resonant frequency the permittivity can be directly extracted with the use of classical formulas. Simulation and measurement results are presented to show the potential of this characterization technique and to validate the concept.