Internet of things: A survey on enabling technologies, application and standardization

Radio-frequency identification (RFID) sensors are one of the fundamental components of the internet of things that aims at connecting every physical object to the cloud for the exchange of information. In this framework, chipless RFIDs are a breakthrough technology because they remove the cost associated with the chip, being at the same time printable, passive, low-power and suitable for harsh environments. After the important results achieved with multibit chipless tags, there is a clear motivation and interest to extend the chipless sensing functionality to physical, chemical, structural and environmental parameters. These potentialities triggered a strong interest in the scientific and industrial community towards this type of application. Temperature and humidity sensors, as well as localization, proximity, and structural health prototypes, have already been demonstrated, and many other sensing applications are foreseen soon. In this review, both the different architectural approaches available for this technology and the requirements related to the materials employed for sensing are summarized. Then, the state-of-the-art of categories of sensors and their applications are reported and discussed. Finally, an analysis of the current limitations and possible solution strategies for this technology are given, together with an overview of expected future developments.

https://www.mdpi.com/1424-8220/20/7/2135/pdf

Chipless RFID Sensors for the Internet of Things: Challenges and Opportunities

Advancement in the technology of leadless cardiac pacemakers (LCPs) has led to ultracompact designs of implantable antennas. In this study, a small-sized antenna for integration with an LCP, which can be operated in the industrial, scientific, and medical (ISM) band of 2.4 GHz, is developed. The proposed antenna was constructed in a spiral shape to provide superior miniaturization, less sensitivity to body tissue variation, and low specific absorption rate (SAR) values, and avoid fabrication complexities due to its small size. The antenna with a footprint of $3 \times 4\,\,\times0.5$ mm3 was constructed on a high dielectric material, namely, Rogers RT/duroid 6010. To the best of the authors’ knowledge, this is the smallest footprint with enhanced performance when compared to previous reports related to implantable antennas. In addition, the antenna was integrated with a 3-D printed LCP having dummy electronics and experimentally validated in saline solution and minced pork. The antenna sustained good impedance matching at the ISM band with a measured bandwidth of 21.88% and 15.46% with the device and without the device, respectively. Due to the smooth electric field (surface currents) over the patch, the antenna system had 270.28 and 31.04 W/kg peak SAR for 1 and 10 g of tissues, respectively, with a maximum peak gain of −25.95 dBi. We also discussed the effects of a coaxial cable and the antenna orientation on its performance. From the measured received signal strength, a stable biotelemetric link can be established between the implant and external controlling device up to a distance of 2 m.

Ultra-Compact Implantable Antenna With Enhanced Performance for Leadless Cardiac Pacemaker System

Chipless Radio Frequency Identification (RFID) has been used in a variety of remote sensing applications and is currently a hot research topic. To date, there have been a large number of chipless RFID tags developed in both academia and in industry that boast a large variation in design characteristics. This review paper sets out to discuss the various design aspects needed in a chipless RFID sensor. Such aspects include: (1) Addressing strategies to allow for unique identification of the tag, (2) Sensing mechanisms used to allow for impedance-based response signal modulation and (3) Sensing materials to introduce the desired impedance change when under the influence of the target stimulus. From the tabular comparison of the various sensing and addressing techniques, it is concluded that although many sensors provide adequate performance characteristics, more work is needed to ensure that this technology is capable/robust enough to operate in many of the applications it has been earmarked for.

A Review of Chipless Remote Sensing Solutions Based on RFID Technology.

This study presents a multi-band conformal antenna based endoscopic system for robust biotelemetry communications, which covers five important bands, including the MedRadio (401-406 MHz), Industrial, Scientific, and Medical (ISM) (433.1-434.8 MHz, 868-868.6 MHz, 902-928 MHz), and midfield (1200 MHz) bands. These bands are intended for functions such as biotelemetry, power saving, and wireless power transfer (WPT). The proposed antenna is printed on a flexible material Rogers ULTRALAM with a thickness of only 0.1 mm, which can be easily wrapped around the inner wall of a capsule. Owing to the insertion of the via and open-ended meandered slots in the radiator and in the ground plane, the footprints of the suggested antenna reduce considerably. In the flat form, the antenna is 57 mm
 3
 in volume, whereas in the wrapped form, it is only 48.98 mm
 3
 in volume. In a homogeneous muscle phantom, the proposed conformal antenna shows a 27.46% wider bandwidth at 402 MHz,whereas it shows a 13.2% and 5.42% bandwidth at 915 MHz and 1200 MHz, respectively. Furthermore, the specific absorption rate investigation at three resonance frequencies in various implanted locations shows compliance with the IEEE guidelines, thereby guaranteeing human safety. For measurements, a 3D capsule with batteries and circuitry is devised using a 3D printer, and the simulation results are experimentally validated in a box containing minced pork. Finally, the robustness of the communication link is confirmed through the link budget analysis at 1 Mb/s. The conformal design concept, omni-directional radiations, and multi-band functionality with a wider bandwidth in the MedRadio band of the suggested antenna will enhance the diversity of the capsule endoscope and be a good addition to the field of biotelemetry.

/pdf/compacted-conformal-implantable-antenna-with-multitasking-500n72xfvn.pdf

Compacted Conformal Implantable Antenna With Multitasking Capabilities for Ingestible Capsule Endoscope

In this communication, a biotelemetry device for scalp implantation is proposed with an ultraminiaturized and simple-structured implantable antenna that exhibits dual-band characteristics in the industrial, scientific, and medical bands (915 MHz and 2.45 GHz). The proposed system incorporates two batteries and microelectronic components in a total volume of 434.72 mm3. The recommended antenna has a reduced volume of 9.8 mm3 (7 mm $\times7$ mm $\times0.2$ mm), which is the smallest antenna presented so far. In homogeneous and heterogeneous environments, the designed antenna system has peak gain values of −28.04 and −28.94 dBi, respectively, at 915 MHz, and −23.01 and −23.06 dBi, respectively, at 2.45 GHz. For validation, the prototype of the antenna and corresponding system are immersed in a 3-D head phantom (saline solution), and the measured results are found in close agreement with the simulation results. Additionally, the data communication range is analyzed through a link budget calculation at several data rates and an input power of −16 dBm. The radiation of the antenna system in the two principal planes (E and H) are similar to being omni-directional and directed away from the anatomical human body model as mandatory for the telemetry applications. Hence, the proposed antenna system can be employed in scalp implantation, especially for intracranial pressure monitoring.

A Miniaturized Dual-Band Implantable Antenna System for Medical Applications

A miniaturized, polarization insensitive, and fully passive chipless radio frequency identification tag is proposed in this research article. The realized tag is based on slotted elliptical structures in a nested loop fashion with identical lengths and widths of slot resonators. Alteration of data sequence is accomplished by addition and elimination of nested resonators in the geometric structure. The tag is capable to encode 10 bits of data and covers spectral range from 3.6 to 15.6 GHz. The formulated structure demonstrates polarization insensitive characteristic. The data encoding structure is analyzed and optimized for different substrates that are, Rogers RT/duroid/5880, Rogers RT/duroid/5870, and Taconic TLX‐0 over the miniaturized footprint of 22.8 × 16 mm2. The presented tag is robust, novel, compact, and flexible exhibiting a stable response to impinging electromagnetic waves at various angles of incidence.

Elliptical slot based polarization insensitive compact and flexible chipless RFID tag

In this paper, we demonstrate the passive chipless RFID tag having C shaped copper resonators operating in ultra wide band (2.5–5.5 GHz). The efficient bandwidth utilization is performed by using the frequency coding technique. The number of possible unique combinations is 210. Measurements and calculations are performed in frequency domain and the results are shown with the help of radar cross section (RCS) plot. The tag design is optimized and analyzed for three different substrates having same compact geometry of 20 × 40 mm2. The comparative analysis shows that the overall bandwidth of FR4, Rogers RT5880 and Taconic TLX-0 is 2.85 GHz, 2.5 GHz and 2.03 GHz respectively. The proposed tag is a suitable candidate for applications requiring high data capacity with an average tag size and simple resonating structures.

Design and analysis of C shaped chipless RFID tag

A novel and miniaturized semi-elliptical 20-bit fully passive chipless RFID sensor tag is proposed in this article. The realized sensor tag is made up of semi-elliptical shaped open-end slots within the compact size of 25 mm × 17 mm. The multi-substrate analysis of the proposed tag is examined using non-flexible and flexible materials. The articulated tag configuration is capable of monitoring moisture levels when the largest resonator is covered by a heat-resistant sheet of Kapton HN (DuPontTM). The proposed tag functions in the operational frequency band of 4.1 GHz–16 GHz and possesses the overall bit density of 4.70 bit/cm2. The structure is composed of a thin passive substrate layer topped with an active layer of conductive path and is considered as a potential candidate for low-cost identification of the tagged objects. In addition to that, its moisture sensing property and flexible nature make it a reliable smart sensor for conformal applications.

https://www.mdpi.com/2079-9292/8/10/1182/pdf

Data-Dense and Miniature Chipless Moisture Sensor RFID Tag for Internet of Things

A novel microstrip patch antenna with dual band notch operation and coplanar waveguide feed (CPW) is proposed in this paper. The initial antenna design efficiently covers the ultra-wideband (UWB) range from 3.1 GHz to 10.6 GHz with VSWR<2. Afterward, the antenna patch is embedded with slotted structures to introduce notches. The upper WLAN (5.54 GHz to 5.82 GHz) and WiMAX (3.35 GHz to 3.6 GHz) bands are notched in the UWB antenna by introducing two U-shaped slots in opposite directions in the radiating patch. From the simulation results obtained in HFSS, it is clearly shown that the proposed design exhibits good performance. The antenna is capable of suppressing two interfering bands in its UWB operation, and it has omnidirectional radiation patterns with high gain. The current density plots are also presented to show the effective area of the antenna to achieve band suppression. The compact size of the proposed antenna makes it suitable for multiple wireless miniaturized devices.

Asma Ejaz

Papers

A Miniaturized Dual-Band Implantable Antenna System for Medical Applications

Elliptical slot based polarization insensitive compact and flexible chipless RFID tag

Design and analysis of C shaped chipless RFID tag

Data-Dense and Miniature Chipless Moisture Sensor RFID Tag for Internet of Things

Dual Band Notch Planar Patch Antenna for UWB Applications