RF Energy Harvesting Techniques for Battery-less Wireless Sensing, Industry 4.0 and Internet of Things: A Review

As the Internet of Things (IoT) continues to expand, the demand for the use of energy-efficient circuits and battery-less devices has grown rapidly. Battery-less operation, zero maintenance and sustainability are the desired features of IoT devices in fifth generation (5G) networks and green Industry 4.0 wireless systems. The integration of energy harvesting systems, IoT devices and 5G networks has the potential impact to digitalize and revolutionize various industries such as Industry 4.0, agriculture, food, and healthcare, by enabling real-time data collection and analysis, mitigating maintenance costs, and improving efficiency. Energy harvesting plays a crucial role in envisioning a low-carbon Net Zero future and holds significant political importance. This survey aims at providing a comprehensive review on various energy harvesting techniques including radio frequency (RF), multi-source hybrid and energy harvesting using additive manufacturing technologies. However, special emphasis is given to RF-based energy harvesting methodologies tailored for battery-free wireless sensing, and powering autonomous low-power electronic circuits and IoT devices. The key design challenges and applications of energy harvesting techniques, as well as the future perspective of System on Chip (SoC) implementation, data digitization in Industry 4.0, next-generation IoT devices, and 5G communications are discussed

Multiport sensor RFIDs for wireless passive sensing of objects - Basic theory and early results

A new family of passive sensor radio-frequency identification devices is here proposed for applications in the context of wireless sensor networks. The new tags, working in the ultra-high frequency band, are able to detect the value or the change of some features of the tagged body without using any specific sensor. Such tags are provided with multiple chips embedded either within a cluster of cooperating antennas or in a single multiport antenna, and exploit the natural mismatch of the antenna input impedance caused by the change of the tagged object. A basic theory of multiport sensor tags is formulated with the purpose to describe the possible classification and detection performances in a unitary context. Some numerical examples and a first experiment corroborate the feasibility of the idea

Microstrip Patch Antenna Miniaturization Using Magneto-Dielectric Substrates for Electromagnetic Energy Harvesting

A mathematical modelling, and a derivation of the main parameters of the Magneto – Dielectric materials (substrate) and their effect on microstrip patch antenna design is shown. The Magneto – Dielectric materials (substrate) is shown to miniaturize the antenna size and enhance the bandwidth when used in the design of the microstrip patch antenna. The progression of the foundational modelling starts with laying out the concepts of the ferrimagnetic materials in terms of their permeability and permittivity, the components of antenna miniaturization. First, a ground free elliptical microstrip patch antenna (GFDSEPA) is simulated for miniaturization purposes at the 900MHz cellular band. A size reduction of almost 50% as well as bandwidth enhancement (100%) is achieved by utilizing the GFDSEPA. More size reduction is achieved by employing the magneto – dielectric structure; in this case the commercially available Rogers MAGTREX 555 substrate is used. Other performance parameters show comparable results between the antenna simulated based on dielectric only substrate and the one based on magneto–dielectric substrate. A comparison of the main parameters between the results of this work and other results in the literature is shown. The application of the microstrip patch antenna design in energy harvesting, by using a rectifier circuit, is shown. Layout scenarios of the energy harvester are proposed. The proposed layout of the energy harvester ensures practicality of the proposed design and assures correlation between simulation results and experimental results

A 21 m Operation Range RFID Tag for “Pick to Light” Applications with a Photovoltaic Harvester

In this paper, a novel Radio-Frequency Identification (RFID) tag for “pick to light” applications is presented. The proposed tag architecture shows the implementation of a novel voltage limiter and a supply voltage (VDD) monitoring circuit to guarantee a correct operation between the tag and the reader for the “pick to light” application. The feasibility to power the tag with different photovoltaic cells is also analyzed, showing the influence of the illuminance level (lx), type of source light (fluorescent, LED or halogen) and type of photovoltaic cell (photodiode or solar cell) on the amount of harvested energy. Measurements show that the photodiodes present a power per unit package area for low illuminance levels (500 lx) of around 0.08 µW/mm2 , which is slightly higher than the measured one for a solar cell of 0.06 µW/mm2 . However, solar cells present a more compact design for the same absolute harvested power due to the large number of required photodiodes in parallel. Finally, an RFID tag prototype for “pick to light” applications is implemented, showing an operation range of 3.7 m in fully passive mode. This operation range can be significantly increased to 21 m when the tag is powered by a solar cell with an illuminance level as low as 100 lx and a halogen bulb as source light

Energy Management in RFID-Sensor Networks: Taxonomy and Challenges

Ubiquitous Computing is foreseen to play an important role for data production and network connectivity in the coming decades. The Internet of Things (IoT) research which has the capability to encapsulate identification potential and sensing capabilities, strives towards the objective of developing seamless, interoperable and securely integrated systems which can be achieved by connecting the Internet with computing devices. This gives way for the evolution of wireless energy harvesting and power transmission using computing devices. Radio Frequency (RF) based Energy Management (EM) has become the backbone for providing energy to wireless integrated systems. The two main techniques for EM in RFID Sensor Networks (RSN) are Energy Harvesting (EH) and Energy Transfer (ET). These techniques enable the dynamic energy level maintenance and optimisation as well as ensuring reliable communication which adheres to the goal of increased network performance and lifetime. In this paper, we present an overview of RSN, its types of integration and relative applications. We then provide the state-of-the-art EM techniques and strategies for RSN from August 2009 till date, thereby reviewing the existing EH and ET mechanisms designed for RSN. The taxonomy on various challenges for EM in RSN has also been articulated for open research directives

RFID multiantenna systems for wireless communications and sensing

Many scientific, industrial and medical applications require the measurement of different physical parameters in order to collect information about the spatially distributed status of some process. Very often this information needs to be collected remotely, either due to the spatial dispersion of the measurement points or due to their inaccessibility. A wireless embedded self-powered sensor may be a convenient solution to be placed at these inaccessible locations. This thesis is devoted to study the analytical relation governing the electromagnetic coupling between a reader and a embeddable self-powered sensor, based on radio frequency identification (RFID) technology, which is capable of wirelessly retrieving the status of physical parameters at a remote and inaccessible location. The physical parameter to be sensed may be the electromagnetic (EM) field existing at that location (primary measurement) or the indirect measurement of other parameters such as the temperature, humidity, etc. (secondary measurement). Given the simplicity of the RFID solution (highly embeddable properties, scavenging capabilities, penetration and radio coverage characteristics, etc.) the measurement can be done at a single location, or it can be extended to a set of measuring locations (an array or grid of sensors). The analytical relation is based on a reciprocity formulation studying the modulation of the scattered field by the embedded sensor in relation with the incident field, and allows to define a set of quality parameters of interest for the optimum design of the sensors. Particular attention is given to the scavenging circuitry as well as to the antenna design relevant to the sensing objective. In RFID tags, the existence of an RF harvesting section is an improvement with respect to conventional scattering field probes since it removes the need of DC biasing lines or optical fibers to modulate the sensor. However, this harvesting section introduces non-linearities in the response of the sensor, which requires a proper correction to use them as EM-field probes, although the characterization of the non-linearities of the RFID tag cannot be directly done using a conventional vector network analyzer (VNA), due to the requirements of an RFID protocol excitation. Due to this, this thesis proposes an alternative measurement approach that allows to characterize the different scattering states used for the modulation, in particular its non-linear behavior. In addittion, and taking this characterization as the starting point, this thesis proposes a new measurement setup for EM-field measurements based on the use of multiple tones to enlarge the available dynamic range, which is experimentally demonstrated in the measurement of a radiation pattern, as well as in imaging applications. The RFID-based sensor response is electromagnetically sensitive to the dielectric properties of its close environment. However, the governing formulation for the response of the probe mixes together a set of different contributions, the path-loss, the antenna impedance, the loads impedance, etc. As a consequence, it is not possible to isolate each contribution from the others using the information available with a conventional RFID sensor. This thesis mathematically proposes and experimentally develops a modification of the modulation scheme to introduce a new set of multi-load scattering states that increases the information available in the response and properly isolate each term. Moreover, this thesis goes a step forward and introduces a new scattering state of the probe sensitive to temperature variations that do not depend on the environment characteristics. This new configuration enables robust environmental sensing in addition to EM-field measurements, and sensing variations of the dielectric properties of the environment

A Review on Antenna Technologies for Ambient RF Energy Harvesting and Wireless Power Transfer: Designs, Challenges and Applications

Radio frequency energy harvesting (RFEH) and wireless power transmission (WPT) are two emerging alternative energy technologies that have the potential to offer wireless energy delivery in the future. One of the key components of RFEH or WPT system is the receiving antenna. The receiving antenna's performance has a considerable impact on the power delivery capability of an RFEH or WPT system. This paper provides a well-rounded review of recent advancements of receiving antennas for RFEH and WPT. Antennas discussed in this paper are categorized as low-profile antennas, multi-band antennas, circularly polarized antennas, and array antennas. A number of contemporary antennas from each category are presented, compared, and discussed with particular emphasis on design approach and performance. Current design and fabrication challenges, future development, open research issues of the antennas and visions for RFEH and WPT are also discussed in this review