Factors Affecting the Synthesis of Autonomous Sensors with RFID Interface

Wireless Capacitive Liquid-Level Detection Sensor Based on Zero-Power RFID-Sensing Architecture

In this paper, a new method for the wireless detection of liquid level is proposed by integrating a capacitive IDC-sensing element with a passive three-port RFID-sensing architecture. The sensing element transduces changes in the liquid level to corresponding fringe-capacitance variations, which alters the phase of the RFID backscattered signal. Variation in capacitance also changes the resonance magnitude of the sensing element, which is associated with a high phase transition. This change in the reactive phase is used as a sensing parameter by the RFID architecture for liquid-level detection. Practical measurements were conducted in a real-world scenario by placing the sensor at a distance of approximately 2 m (with a maximum range of about 7 m) from the RFID reader. The results show that the sensor node offers a high sensitivity of 2.15°/mm to the liquid-level variation. Additionally, the sensor can be used within or outside the container for the accurate measurement of conductive- or non-conductive-type liquids due to the use of polyethylene coating on the sensitive element. The proposed sensor increases the reliability of the current level sensors by eliminating the internal power source as well as complex signal-processing circuits, and it offers real-time response, linearity, high sensitivity, and excellent repeatability, which are suitable for widespread deployment of sensor node applications.

The Idea of RFIDtex Transponders Utilization in Household Appliances on the Example of a Washing Machine Demonstrator

Modern textronic RFID transponders offer a lot of new possibilities for household appliances designers. Possibility to implement new functions is most evident in clothes washing and ironing techniques, where the information stored in the memory of the RFID transponder sewn into the textiles can be used to choose the most appropriate ironing program for a given type of fabric or to select the best washing program for different clothes placed in a drum of washing machine. The purpose of the work was to propose, design, and develop a laboratory stand to demonstrate usage of RFIDtex transponders in a washing machine. The developed device enabled simulation of the presence of textiles equipped with RFIDtex transponders in a washing machine drum. A set of measurements of the constructed device readout efficiency of textronic transponders placed in the drum was also performed. The device firmware, which manages multiple data readings from tags inside the drum for the performed by integrated RWD (read/write device), was also prepared and implemented. This allowed the efficiency of the identification of textiles equipped with RFIDtex transponders to be increased. RFIDtex transponders can also be used in the future to provide precise information about textiles to the washing machine. Based on this information, device will be able to reduce power consumption.

RFID Sensors for Monitoring Glazing Units Integrating Photovoltaic Modules

The paper focuses on the synthesis of semi-passive RFID transponders-sensors that are intended to integrate with active glazing units with built-in photovoltaic cells. The main purpose of the designed construction of the UHF RFID device is to provide diagnostic information in the monitoring system of a photovoltaic micro-power plant. Furthermore, the RFID sensor is aimed at being implemented at various stages of the product life cycle: production, distribution, storage, installation, common operation, service/maintenance and disposal. In the presented research work, particular attention is paid to several aspects of the RFID sensor synthesis: use of the energy, generated periodically in the PV cells, to power the monitoring device that has to act permanently; specification of the PV module parameters that have to be monitored in the diagnostic process; implementation of data acquisition and energy management models in an electrical circuit; wireless data transfer to the master unit (monitoring host), even in the absence of power supply (e.g., module damage, blackout), using a standardized communication protocol IEC 18000-63 used in the RFID technology; and the design of the antenna system taking into consideration limitations of electronic technology and the material properties of substrates and glasses used in PV modules and RFID sensors. Based on the results of the investigations, the modular structure of the RFID sensor demonstrator is proposed. Moreover, several diagnostic scenarios are analyzed in detail. On the basis of the provided considerations, it is shown that in order to find a malfunctioning component, it is enough to compare the voltages on the photovoltaic modules that are in the close vicinity.

A Survey on Battery-Less RFID-Based Wireless Sensors

We present a survey on battery-less Radio Frequency Identification (RFID-based wireless sensors that have emerged in the past several years. We discuss the evolution of RFID turning into wireless sensors. Moreover, we talk about different components of these battery-less RFID-based wireless sensors, five main topologies that transform a simple RFID chip into a battery-less wireless sensor, and state-of-the-art implementations of these topologies. In battery-less wireless sensors, the read range is of key importance. Hence, we discuss how each component of the sensor plays its role in determining the read range and how each topology exploits these components to optimize read range, complexity, and/or cost. Additionally, we discuss potential future directions that can help provide improvements in RFID-based wireless sensor technology.

Textronic UHF RFID Transponder

In order to respond the growing interest towards radio frequency identification textile transponders, the authors propose a new approach to design radio frequency identification (RFID) devices by introducing the RFIDtex concept. The coupling system of inductive loops is implemented in the textronic structure with the RFID interface in order to split the transponder into two independently manufactured components. Then both modules can be easily integrated into the RFIDtex tag. The presented simulation and measurement results prove the concept of manufacturing a relatively small antenna in the form of a meandered dipole sewn in with a single thread, and further, that can be connected to the RFID chip through the coupling system without galvanic junctions. The achieved parameters clearly indicate that the tag can correctly communicate with the read/write device as well as the coupling between its both parts works properly, and the impedance matching is possible in this case. The possibility of confectioning products with electronic identification tags at the textile factory site and improved resistance to the impact of environmental conditions are the main advantage of the proposed approach to the RFID devices designing. The RFIDtex transponder idea proposed by the authors was restricted in the patent no PL 231291 B1.

Dynamic RFID Identification in Urban Traffic Management Systems

The paper covers the application of Radio Frequency IDentification (RFID) technology in road traffic management with regard to vehicle identification. Various infrastructure configurations for Automated Vehicle Identification (AVI) have been presented, including configurations that can be used in urban traffic as part of the Smart City concept. In order to describe the behavior of multiple identifications of moving vehicles, an operation model of the dynamic identification using RFID is described. While it extends the definition of the correct work zone, this paper introduces the concept of dividing the zone into sections corresponding to so-called inventory rounds. The system state is described using a set of matrices in which unread, read, and lost transponders are recorded in subsequent rounds and sections. A simplified algorithm of the dynamic object identification system was also proposed. The results of the simulations and lab experiments show that the efficiency of mobile object identification is conditioned by the parameters of the communication protocol, the speed of movement, and the number of objects.

Wireless Power Transfer Techniques for Implantable Medical Devices: A Review

Wireless power transfer (WPT) systems have become increasingly suitable solutions for the electrical powering of advanced multifunctional micro-electronic devices such as those found in current biomedical implants. The design and implementation of high power transfer efficiency WPT systems are, however, challenging. The size of the WPT system, the separation distance between the outside environment and location of the implanted medical device inside the body, the operating frequency and tissue safety due to power dissipation are key parameters to consider in the design of WPT systems. This article provides a systematic review of the wide range of WPT systems that have been investigated over the last two decades to improve overall system performance. The various strategies implemented to transfer wireless power in implantable medical devices (IMDs) were reviewed, which includes capacitive coupling, inductive coupling, magnetic resonance coupling and, more recently, acoustic and optical powering methods. The strengths and limitations of all these techniques are benchmarked against each other and particular emphasis is placed on comparing the implanted receiver size, the WPT distance, power transfer efficiency and tissue safety presented by the resulting systems. Necessary improvements and trends of each WPT techniques are also indicated per specific IMD.

Designing Antennas for RFID Sensors in Monitoring Parameters of Photovoltaic Panels

The importance of the radio-frequency identification (RFID) technology and photovoltaic (PV) systems has been growing systematically in the modern world full of intelligent products connected to the Internet. Monitoring parameters of green energy plants is a crucial issue for efficient conversion of solar radiation, and cheap RFID transponders/sensors can be involved in this process to provide better performance of module supervision in scattered installations. Since many components of PV panels disturb the radio-wave propagation, research in the antenna scope has to be carried out to reach the proposed fusion. The problem with RFID transponders being detuned in close proximity to glass or metal surfaces can be solved on the basis of solutions known from the scientific literature. The authors went further, revealing a new antenna construction that can be fabricated straight on a cover glass of the PV panels. To achieve the established task, they incorporated advantages from the latest advancements in materials technology and low-power electronics and from the progress in understanding radio-wave propagation phenomena. The numerical model of the antenna was elaborated in the Hyper Lynx 3D EM software environment, and test samples were fabricated on the technology line of ML System Company. The convergence of calculated and measured antenna parameters confirms the design correctness. Thus, the studied antenna can be used to elaborate the cheap semipassive RFID transponders/sensors in the PV panel production lines.