Near-field Communication Antenna Research Articles

A mechanics and electromagnetic scaling law for highly stretchable radio frequency electronics

Many classes of flexible and stretchable bio-integrated electronic systems rely on mechanically sensitive electromagnetic components, such as various forms of antennas for wireless communication and for harvesting energy through coupling with external power sources. This efficient wireless functionality can be important for body area network technologies and can enable operation without the weight and bulky size of batteries for power supply. Recently, antenna designs have received increased attention because their mechanical and electromagnetic properties significantly influence the wireless performance of bio-integrated electronics, particularly under excessive mechanical loads. These mechanical factors are critical for skin-integrated electronics during human motion, as complex skin deformations can damage the conductive traces of antennas, such as those used for near-field communication (NFC), leading to yield or fracture and affecting their electromagnetic stability. Serpentine interconnects have been proposed as a geometric alternative to in-plane circular or rectangular spiral antenna designs to improve the elastic stretchability of the metallic traces in NFC antennas and prevent mechanical fractures. Despite the use of serpentine interconnects within the physiologically relevant strain range for skin (<20 %), the electromagnetic stability of the antennas decreases. This instability, reflected by shifts in resonance frequency and scattering parameters due to inductance changes, reduces the antennas' wireless power transfer efficiency and readout range. Therefore, maintaining the electromagnetic stability of antennas, specifically NFC antennas, under various mechanical deformations has become a critical challenge in practical wireless skin-integrated applications, such as sensing and physiological monitoring. Here, we establish a new mechanics and electromagnetic scaling law that quantifies the inductance changes under strain in a rectangular-loop serpentine structure typically used for NFC wireless communication in stretchable electronics. We present a systematic analysis of the antenna's geometric parameters, material properties of the antenna and substrate, and the applied strain on the inductance change. Our findings demonstrate that the relative change of inductance is solely influenced by the serpentine structure's width-radius ratio, arc angle, aspect ratio of the NFC antennas, and the applied strain. Additionally, under physiological strain conditions for the skin, the relative change of inductance can be minimized to preserve the NFC antenna's performance and prevent mechanical fracture and electromagnetic stability loss.

Highly stretchable, deformation-stable wireless powering antenna for wearable electronics

Near-field communication (NFC) antennas, which use electromagnetic coupling technology to realize wireless transmission and energy harvesting over short distances, are widely used in wearable and implantable electronics. However, mechanical deformations are inevitable in practical applications, which usually have serious effects on their resonant frequency and quality factor, resulting in communication failure. Here, we report a highly stretchable, deformation-stable NFC antenna (SDNA) based on a spider-web structure and liquid-metal microchannels. Results of the finite element analysis and experimental tests suggest that the proposed antenna is insensitive to tensile loading and has smaller inductance variation and resonance frequency shift. The antenna frequency is only offset by 2.75 MHz with a strain of 300 %. Its robustness and stability are verified under diverse circumstances, including folding (0–170°), bending (2.5–20 mm), twisting (0–270°), rolling (0–360°), overall pressure (1000 kPa), and cyclic stretching (5000 times). Its resonant frequency remains still stable when mounted on a contracting and expanding balloon or the moving knee joints (0–9 km/h). Based on its excellent stretchability and stability, the proposed SDNA is ideal to be used for wearable electronics, such as smart clothing. In summary, the proposed antenna has considerable potential for applications in wearable and implantable electronics.

DESIGN OF NEAR FIELD COMMUNICATION PASSIVE ANTENNA FOR CIRCULAR SHAPED WEARABLE ITEMS

The paper discusses proposed Near Field Communication (NFC) passive antenna design for circular and round shaped wearable items like rings, watches and wristbands. Several NFC passive tags were available in the market, which had different shaped antennas, incorporated into them. However, these tags were designed with specific shape and diameter and could not fit for most of the wearable items like rings, watches and wristbands etc. In order to overcome this problem, a customized NFC antenna for passive tags was designed, which could be suitable for circular shaped wearable items. Moreover, comparative analysis of proposed antenna with vendor made antenna had been performed to show how proposed customized antenna was much more efficient in performance.

25.1: Invited Paper: Novel design and Study of NFC(Near Field Communication) Coil integrated in OLED display Panel and MFPC(Main Flexible Printed Circuit)

In this work, we have successfully developed an integrated NFC antenna in a 1.57 inch panel. We have made NFC coils on both panel edge and MFPC and connected them through bonding process. The novel interface makes it possible for the user to interact directly with digital information through the display panel. NFC recognition on the front surface of the watch display has been achieved and reader recognition distance can be 33mm (NFC Forum Type 2 Tag). The NFC antenna integrated in a FMLOC (Flexible Multi-Layer on Cell)-structured panel has demonstrated premium display performance as well as high touch sensitivity of above 47.512dB SNR(signal noise ratio) for φ10 Copper rods. When the NFC is switched to the reader mode, no obvious flicker can be observed if proper time sequence is adopted. As a result, our NFC-integrated display panel prototype has achieved high sensitivity and stable signal transmission without affecting touch performance and display quality.

Laser‐Scribed Graphene–Polyaniline Microsupercapacitor for Internet‐of‐Things Applications

AbstractThe push toward smart technologies and the Internet‐of‐Things (IoT) demands the development of miniaturized energy storage devices. Herein, a facile and scalable strategy is presented, based on laser reduction of graphene oxide into graphene followed by electrodeposition of polyaniline (PANi), to fabricate a substrate‐free supercapacitor. The fabricated supercapacitor is part of a flexible multifunctional integrated system comprising a thin‐film humidity sensor, a resistor, and a near field communication (NFC) antenna for IoT‐linked wireless communication with a smartphone. The integrated sensory system shares laser‐scribed graphene (LSG) as the same electrode material for all the components (supercapacitor, sensor, resistor, and NFC antenna). The symmetric LSG‐PANi||LSG‐PANi supercapacitor with wireless charging capability exhibits a near record‐high energy density of 0.407 mW h cm−3, and excellent power density of 196 mW cm−3, along with an outstanding rate capability (enduring high rates of over 1 V s−1). As a humidity sensor, the device demonstrates high resistance changes from 2000 kΩ at 0% relative humidity (RH) to 497 kΩ at 100% RH (15 kΩ per RH%) with a sub‐second scale (0.87 s) response time. This research paves the way for limitless applications of IoT across a wide spectrum of fields from healthcare to chip‐based electronics to environmental monitoring.

An ultra-compact and wireless tag for battery-free sweat glucose monitoring

Glucose monitoring before, during, and after exercise is essential for people with diabetes as exercise increases the risk of activity-induced hyper- and hypo-glycemic events. The situation is even more challenging for athletes with diabetes as they have impaired metabolic control compared to sedentary individuals. In this regard, a compact and noninvasive wearable glucose monitoring device that can be easily worn is critical to enabling glucose monitoring. This report presents an ultra-compact glucose tag with a footprint and weight of 1.2 cm2 and 0.13 g, respectively, for sweat analysis. The device comprises a near field communication (NFC) chip, antenna, electrochemical sensor, and microfluidic channels implemented in different material layers. The device has a flexible and conformal structure and can be easily attached to different body parts. The battery-less operation of the device was enabled by NFC-based wireless power transmission and the compact antenna. Femtosecond laser ablation was employed to fabricate a highly compact and flexible NFC antenna. The proposed device demonstrated excellent operating characteristics with a limit of detection (LOD), limit of quantification (LOQ), and sensitivity of 24 μM, 74 μM, and 1.27 μA cm−2 mM−1, respectively. The response of the proposed sensor in sweat glucose detection and quantification was validated by nuclear magnetic resonance spectroscopy (NMR). Also, the device's capability in attachment to the body, sweat collection, and glucose measurement was demonstrated through in vitro and in vivo experiments, and satisfactory results were obtained.

Femtosecond Laser Ablation Assisted NFC Antenna Fabrication for Smart Contact Lenses

AbstractSmart contact lenses (SCLs) have drawn substantial interest for continuous health monitoring applications. Even though most of the reported works utilize near‐field communication (NFC) or inductive coupling for wireless powering and data transmission, developing a scalable and rapid fabrication technique for annular ring antennas confined in a small contact lens area is still an unsolved challenge. Here, femtosecond laser ablation is employed for the first time as a simple, single‐step, and highly precise fabrication technique for NFC antennas using conventional flexible printed circuit board materials. Antenna lines with depth and width of 9 and 35 μm are achieved, respectively. The antenna with a footprint of 19.5 mm2 is characterized in biological solution followed by aging, and bending tests, and a frequency deviation of less than %1 is recorded. A real‐life application is demonstrated by fabricating an SCL embedded with the antenna, an NFC chip, and an electrochemical sensor for wireless monitoring of glucose in artificial tear solution by a smartphone. The device could successfully quantify biologically relevant glucose concentrations ranging from 0.2 to 1 mM with a limit‐of‐detection of 66 μM. In addition, device response to interfering molecules is less than ±1 nA, and the spike‐and‐recovery test is successfully demonstrated.

A Wearable NFC Antenna Sewn on Leather Substrate for Immersive IoT Applications

The Internet of Things (IoT) is considered a promising realm of innovation and revenue generation for the forthcoming years, revolutionizing the way we interact with objects, other people and the world. With an unprecedented but realistic target of trillions of interconnected devices, the IoT calls for technological innovations that lie in the heart of rapid, low-energy and user-friendly communication between people and things. In this respect, the Near Field Communication (NFC) protocol offers advanced efficiency and applicability with low energy consumption, ease of use, flexibility, and increased payload. NFC tags may be embedded in everyday objects, including clothing and apparel, offering an immersive user experience. Wearable NFC antennas and NFC tags embedded in clothing have been presented in the past; nonetheless, in this paper we present, to the best of our knowledge, the first reported development of a NFC antenna on leather substrate. The proposed antenna is sewn using stainless steel thread and operates at the 13.56 MHz frequency range. It may be used alongside with NFC tags in leather apparel like clothing, shoes, accessories, etc., thus extending the possible use cases and applications of the NFC technology and offering an all the more immersive experience for the end user.

OPTIMIZATION OF NFC ANTENNA TO MICROCONTROLLER’S BOARD DIMENSIONS

This paper is focused on Near-Field Communication (NFC), which is one of the most popular wireless communication. Although the NFC was developed in recent years, it is inseparable part of the everyday activities. NFC antenna is the key element for the realization of the NFC. This paper deals with the design of the miniaturized NFC antenna. Basic equations for coil inductance calculation, which are necessary for the NFC antenna design are presented as well. This paper also focuses on the influence of the coil’s aspect ratio to its inductance. The aim of this paper was the optimization of the NFC antenna dimensions. NFC antenna dimensions were calculated according to dimension of microcontroller Printed Circuit Board (PCB), so the antenna can be laminated directly to microcontroller PCB.

Smartphone-Based NFC Potentiostat for Wireless Electrochemical Sensing

Most electrochemical sensing requires affordable, portable and easy-to-use electrochemical devices for use in point-of-care testing and resource-limited settings. This work presents the design and evaluates the analytical performance of a near-field communication (NFC) potentiostat, a flat card-sized electrochemical device containing a microchip for electrical analysis and an NFC antenna for smartphone connection. The NFC interface is a wireless connection between the microchip and smartphone to simplify measuring units and make the potentiostat into a passive operated device, running without a battery. The proposed potentiostat can perform the common electrochemical techniques including cyclic voltammetry and chronoamperometry with a current range and voltage range of ±20 µA and ±0.8 V. The performance of the NFC potentiostat is compared to a commercial benchtop potentiostat using ferricyanide as a standard solution. The results show that the NFC potentiostat is comparable to a commercial benchtop potentiostat for both cyclic voltammetry and chronoamperometry measurements. The application of the proposed potentiostat is demonstrated by measuring ascorbic acid concentration. As described, the NFC potentiostat, which is compatible with a smartphone, is low-cost, small in size and user-friendly. Thus, the device can be developed for on-site measurement to apply in various fields.

An NFC-Connected Coupler Using IPT-CPT-Combined Wireless Charging for Metal-Cover Smartphone Applications

A near field communication (NFC)-connected coupler using inductive power transfer (IPT)-capacitive power transfer (CPT)-combined wireless charging is proposed for metal-cover smartphone applications. To mitigate eddy current loss in the metal cover, CPT is introduced. Compared with traditional CPT, wireless power transfer through a metal cover is realized, and cost and valuable space inside the smartphone are saved. To achieve CPT through a metal cover, the metal cover itself is separated by a cross slot and utilized as receiving plates. To reduce the voltage across the metal cover within a safety range, IPT is applied. The already-existing NFC antenna is first used as the receiving coil for IPT and also performs as the compensated inductance for CPT. By connecting one of its feed lines to the metal cover, only a parallel external capacitor is needed to construct the receiver of the proposed coupler because the metal cover and NFC antenna are components that already exist inside the smartphone, which greatly saves space inside the smartphone and cost for the proposed coupler. Prototypes of the proposed NFC-connected coupler with and without actual smartphone have been built. The wireless power transfer through metal cover by IPT and CPT has been validated via experiment.

Miniaturized On-Chip NFC Antenna versus Screen-Printed Antenna for the Flexible Disposable Sensor Strips

With the ongoing trend toward miniaturization via system-on-chip (SoC), both radio-frequency (RF) SoCs and on-chip multi-sensory systems are gaining significance. This paper compares the inductance of a miniaturized on-chip near field communication (NFC) antenna versus the conventional screen-printed on-substrate ones that have been used for the transfer of sensory data from a chip to a cell phone reader. Furthermore, the transferred power efficiency in a coupled NFC system is calculated for various chip coil geometries and the results are compared. The proposed NFC antenna was fabricated via a lithography process for an application-specific integrated circuit (ASIC) chip. The chip had a small area of 2.4 × 2.4 mm2, therefore a miniaturized NFC antenna was designed, whereas the screen-printed on-substrate antennas had an area of 35 × 51 mm2. This paper investigates the effects of different parameters such as conductor thickness and materials, double layering, and employing ferrite layers with different thicknesses on the performance of the on-chip antennas using full-wave simulations. The presence of a ferrite layer to increase the inductance of the antenna and mitigate the interactions with backplates has proven useful. The best performance was obtained via double-layering of the coils, which was similar to on-substrate antennas, while a size reduction of 99.68% was gained. Consequently, the coupling factors and maximum achievable power transmission efficiency of the on-chip antenna and on-substrate antenna were studied and compared.

Radio Frequency IDentification for Meat Supply-Chain Digitalisation.

Digitalised supply-chain traceability systems can offer wide prospects both for improving safety as well as enhancing perceived quality. However, the coupling between physical goods and information is often difficult for agri-food items. A solution could be the use of RFID (Radio Frequency IDentification) systems. Due to its wide reading range, Ultra-High Frequency (UHF) technology is already widely used in logistics and warehousing, mostly for the identification of batches of items. A growing interest is also emerging in Near Field Communication (NFC), as several smartphones embed an integrated NFC antenna. This paper deals with the automatic identification of meat products at item level, proposing and evaluating the adoption of different RFID technologies. Different UHF and NFC solutions are proposed, which benchmark tag performances in different configurations, including four meat types (fatty beef, lean beef, chicken and pork), by using a specifically designed test bench. As avoiding the application of two different tags could be advantageous, dual frequency devices (UHF and NFC) are also considered. Significant differences in tag performances, which also depend on meat type and packaging, are highlighted. The paper highlights that tag positioning should consider the geometry of the packaging and the relative positioning of tag, meat and reader antenna.

Improving the Efficiency of NFC Systems Through Optimizing the Sintered Ferrite Sheet Thickness Selection

The reduction of embedded portable devices involves a magnetic field interference problem when it integrates near field communication (NFC) due to the presence of conductive surfaces, such as ground planes, batteries, or metallic enclosures. Flexible sintered ferrite sheets (FSFS) represent an interesting shielding solution to prevent electromagnetic interferences problems related to NFC, thanks to their ability to control the magnetic flux. The characterization of FSFS effectiveness is analyzed as a function of the sheet thickness in this contribution. This is performed with the aim of determining which is the optimum thickness value to retune an NFC antenna to its original operation frequency value (13.56 MHz) when it is affected by a near conductive surface. A finite element method simulation model is designed and corroborated with the experimental results to evaluate the performance of different FSFS thicknesses in terms of resonant frequency shift, magnetic field strength, and communication distance. An electromagnetic scanner is also used to determine the ability of the best FSFS thickness to shield an NFC transmitter antenna when a battery is set under it, emulating a usual problem. The results obtained show that the magnetic field strength is significantly attenuated and the communication distance is highly shorted. Therefore, besides selecting a material that provides high reflection and low losses at 13.56 MHz, thickness must be considered to ensure the greatest communication effectiveness. Consequently, the use of a wrong FSFS thickness could lead to shifting the resonance frequency to lower values than expected, detuning the communication.

Smart Textile Integrated Wireless Powered Near Field Communication Body Temperature and Sweat Sensing System

Near field communication (NFC) is a short-range wireless communication technique that has become an attractive device for healthcare and wellbeing monitoring. The work reported here demonstrates the development of a battery free wearable sensing system with temperature and sweat sensors embedded into and powered by a smart textile NFC antenna. The NFC antenna is seamlessly integrated with closed-body garments, and the sensor data can be easily acquired by NFC readers and smart phones in order to achieve real time and wireless monitor of health status in a convenient and nonintrusive way. A Dickson charge pump circuit has been designed and implemented in order to pump up the voltage and ensure a steady voltage supply for the sweat sensor. The maximum read range for accessing sensor data is 6 cm. The on-body measurement accuracy of the temperature sensor and sweat sensor are able to achieve ±0.14 °C and ±0.2%, respectively. The presented system can provide wearable battery-free ubiquitous wireless connectivity for point-of-care and any time healthcare and wellbeing monitoring.

A Useful Methodology to Convert the Smartphone Metal Cover Into an Antenna Booster for NFC Applications

A useful method to transform the smartphone metal cover into an antenna booster for near-field communication (NFC) antenna installed in a full metal cover (FMC) smartphone is proposed. In this proposed work, by properly embedding a series capacitor into a meticulously selected location within the metal cover, strong coupling between the NFC antenna coil and the metal cover will be generated, which mitigates the reverse eddy current induced on the metal cover. Because of that, the performance of the NFC antenna (located below a narrow horizontal slot-loaded metal cover) is substantially improved, as compared to a reference stand-alone NFC antenna in free-space conditions. To verify this proposed methodology, an ordinary single-turn coil reference NFC antenna 1 (ref 1) and a 3-turn coil reference NFC antenna 2 (ref 2) are initially designed via simulation, followed by the conducting of several typical experiments on these two reference antennas. Finally, the two reference prototype NFC antennas that have utilized this method for a single horizontal slot-loaded FMC are also certified by the Europay, MasterCard, and Visa (EMV) test.

Near‐field communication passive medical detection system employing ponded energy strategy

A low-cost and passive medical examination solution based on near-field communication (NFC) technology is presented in this Letter. NFC antenna is responsible for inducing energy from the smartphone and transmitting data. The signal of medical sensor is acquired and calculated by microcontroller; the result is sent to the smartphone by NFC and displayed on Android application. In order to adapt to the low energy induction of NFC, maximum output of 5 mA at 3 V, a ponded energy method based on time control is designed to achieve that higher power consumption at time of signal acquisition. A body temperature detection prototype was fabricated to verify such medical detection system. Experimental results show that the system can work stably.

P‐140: Embedded NFC Antenna Display Design for Contactless EMVCo Application

A series of Near Field Communication (NFC) antenna was design for embedded in LCD display module attempt to pass analogue power transfer at 13.56MHz used for EMV@ (Europay, MasterCard and Visa) contactless payment transaction. However it was found that magnetic fields seems to seriously interfere by the display if antenna located behind the display module although increasing magnetic field strength of transmitter. As gradually built up the understanding of magnetic field interaction with LCD panel we find that is difficult to pass EMV@ contactless specification by antenna optimized design only if there’s no display modification. The antenna structure proposed in this paper has been designed and simulated with frequency solver CST 2018. Finally, we proposed a total solution, an optimized NFC antenna transmitter embedded with a modified LCD structure that can pass EMV@ contactless analogue power transfer criteria within specific testing volume.

NFC-Enabled Far-Field Antenna on PET Flexible Substrate for 3G/4G/LTE Mobile Devices

This research presents a far-field (FF) antenna with near-field communication (NFC) capability for 3G/4G/LTE mobile devices. The integrated farand near-field communication (FNFC) antenna was fabricated using conductive silver ink on polyethylene terephthalate (PET) flexible substrate. The FF segment of the antenna is operable in the frequency range of 1.8-2.1 GHz, and the NFC antenna is of dual loop and operable at 13.56 MHz. In the antenna realization, simulations were performed and, to validate, an antenna prototype was fabricated. The experimental results revealed that the FF antenna achieved an impedance bandwidth of 37% (1.52-2.21 GHz), given |S11| of less than -6 dB, with the minimum and maximum efficiency of 92.1% and 98%. The experimental gains are 1.76-2.08 dBi across the target operating frequency band, with near-omnidirectional radiation pattern. The simulation and experimental results are in good agreement. Moreover, the FNFC antenna achieves strong magnetic field distributions in H x , H y , and H z orientations and holds promising potential for 3G/4G/LTE applications.

IoT-Linked Integrated NFC and Dual Band UHF/2.45 GHz RFID Reader Antenna Scheme

This research proposes a system board of integrated antenna scheme of near-field communication (NFC) and dual band ultra-high frequency (UHF, 920–925 MHz)/2.45 GHz radio frequency identification (RFID) reader antennas for Internet of Things (IoT) applications. The integrated antenna scheme is capable of simultaneous execution of NFC and UHF RFID functions whereby the NFC and UHF RFID modules, which are serially connected to a microcontroller with Wi-Fi module (NodeMCU), read the universal identification (UID) of NFC and UHF RFID tags. The data are then forwarded to a cloud server via Internet of Things (IoT) and are viewable on smartphones using Blynk mobile application via IoT. To realize the optimal antenna design, simulations were carried out using CST Studio Suite. Prototype antennas were subsequently fabricated and integrated into the system board for IoT-linked near- and far-field communication. The simulation and measured results are in good agreement. The NFC reader antenna resonates at 13.56 MHz, and the dual band UHF/2.45 GHz RFID reader antenna achieves the 920–925 MHz and microwave (MW) bands with high isolation. The novelty of the proposed integrated NFC and UHF RFID antenna scheme lies in the use of cloud technology to store real-time and archival data, in place of traditional servers. The integrated antenna scheme could achieve the NFC, UHF, and MW frequency bands, rendering it ideal for IoT applications.