NFC Antenna Research Articles

Long-range over-a-meter NFC link budget with distributed large-area coils

Near-field communication is considered to have a high level of hardware security protection owing to its natural short-range wireless operation, which makes a man-in-the-middle attack impossible. Here we question this statement by demonstrating a several-meter range NFC communication channel, supported by resonance-tuned large-area distributed coils. Typical NFC antenna architectures encompass multi-turn wires, forming flat resonant coils. Being several centimeters across, those devices cannot provide reliable communication between items, situated more than a fraction of a meter apart. An appealing approach to the range extension is to enlarge the coil area, thus spreading the magnetic field over larger distances. However, in this case, the overall length of folded conducting wires becomes wavelength comparable, nevertheless, the overall size of the coil remains electrically small, considering the 13.56 MHz operation frequency. Here we demonstrate several coil designs and establish a reliable NFC channel over several-meter distances. Adaptive impedance matching is implemented to maintain an energy power transfer between resonant coils, thus further extending the communication channel and making it robust to clutter. The ability for long-range NFC communication raises security concerns in sensitive contactless operations like wireless payments, prompting the need for enhanced countermeasures due to potential hardware vulnerabilities.

The enhanced electromagnetic shielding effect in the design and simulation of NFC antenna employing optimized NiCuZn ferrite composition with improved magneto-dielectric properties and low-temperature sintering characteristics

In this study, a novel NiCuZn (Ni0.24Cu0.21Zn0.55BixFe2-xO4 (x = 0,0.025, 0.050, 0.075)) ferrite composition (Ni/Zn molar ratio is 24/55) was successfully prepared by the addition of Bi3+ ion for substitution. It is demonstrated that Bi2O3 served as an effective doping agent to reduce the sintering temperature to 900 °C and enhanced the high-frequency magneto-dielectric properties. Notably, the maximum permeability is ∼118 (@ 13.56 MHz) when x = 0.050 with a cut-off frequency of 47 MHz, which is nearly four times higher than that of the unsubstituted sample. In addition, an NFC antenna employing optimized ferrite as an electromagnetic shield sheet was designed and simulated. The results indicated that the chaotic and weakened magnetic field was recovered, and the biased resonant frequency was restored from 31.87 MHz to 13.68 MHz. These findings hold significant scientific importance and practical value in achieving superior electromagnetic shielding performance and miniaturization in NFC system.

18‐4: Distinguished Paper: TDDI Panel of NFC Integration Driving Method Based on Part‐time Driving Strategy

In this paper, we demonstrated the front NFC card swipe and touch display in TDDI LCD through the technologies shown later. New NFC sampling and noise reduction algorithm was used to reduce the generation of the Ghost Position and Touch Failure. The Time Division Multiplexing was applied to optimize the noise interference when NFC works. Meanwhile, we integrated the NFC antenna in the TDDI LCD, and also added new display signal filter circuit and VCOM driver signal. In the NFC in‐cell demo, front NFC swiping distance of 50mm is achieved.

Near‐field communication integration into in‐cell touch thin‐film‐transistor liquid‐crystal display

AbstractIn this paper, we demonstrated the front NFC card swipe and touch display in Touch and Display Driver Integration (TDDI) liquid crystal display (LCD) through the technologies shown later. A new NFC sampling and noise reduction algorithm was used to reduce the generation of the ghost position and touch failure. The touch/NFC part‐time driving was applied to optimize the noise interference when NFC works. Meanwhile, we integrated the NFC antenna in the TDDI LCD and added a new display signal filter circuit and VCOM driver signal. In the NFC in‐cell demo, front NFC swiping distance of 60 mm is achieved.

70‐2: Modification of Pixel Design for NFC Antenna Integrated in LCD Panel

As a greatly pragmatic function on mobile phones and other mobile terminals, near‐field communication brings extremely convenience to people. The module designed on the back of the mobile phone terminal contains independent antenna coils, matching circuits, driver ICs and other structures. Based on BOE's proposal of a coil structure integrated in the display pixel in 2021 and preliminary verification of the communication effect, this paper proposes a revised design of the pixel coil structure to improve the communication performance of NFC coil.

P‐7.14: Design of Matching Circuit for NFC Antenna Integrated with Display

The key points of NFC Antenna Integrated with LCD display system are to find the optimal design of matching circuit. Mainly, this design of matching circuit study how to achieve maximum RF energy coupling between matching circuit and tag antenna. In order to achieve optimal matching, it is necessary to increase the series resistance before the filter circuit and cancel the series resistance connected to the antenna Finally, this paper optimizes the balance circuit of the traditional matching circuit of the NFC antenna recommended by the NXP chip, and uses ADS software and Smith chart matching simulation to verify the effectiveness of the circuit.

P‐102: Design Approach of NFC Antenna Integration into LCD Panel

A NFC antenna prototype integrated in a 5.65‐inch LCD panel has been developed, to guarantee NFC antenna is compatible with metal cover and improve user interaction experience. Compared with the traditional FPC‐based or PCB‐based NFC antenna, the main advantage of glass‐based NFC antenna is that it can obtain sufficient magnetic flux through a larger coil area, because there is no interference problem of the mechanical structure, benefit from the ferrite which has been added in the backlight. The design approach of NFC antenna integrated in LCD panel was expounded, the key parameters (such as coil area, shape of backlight backcover) of the module was determined by evaluating the magnetic field distribution through simulation platform. Finally, the experiment achieved a detection range of 40mm, which verify the effectiveness of the simulation model and proposed design approach.

Use of Nanocellulose to Produce Water-Based Conductive Inks with Ag NPs for Printed Electronics.

The need for more sustainable printed electronics has emerged in the past years. Due to this, the use of nanocellulose (NC) extracted from cellulose has recently been demonstrated to provide interesting materials such as functional inks and transparent flexible films due to its properties. Its high specific surface area together with the high content of reactive hydroxyl groups provide a highly tailorable surface chemistry with applications in ink formulations as a stabilizing, capping, binding and templating agent. Moreover, NC mechanical, physical and thermal properties (high strength, low porosity and high thermal stability, respectively) provide an excellent alternative for the currently used plastic films. In this work, we present a process for the production of water-based conductive inks that uses NC both as a template for silver nanoparticles (Ag NPs) formation and as an ink additive for ink formulation. The new inks present an electrical conductivity up to 2 × 106 S/m, which is in the range of current commercially available conductive inks. Finally, the new Ag NP/NC-based conductive inks have been tested to fabricate NFC antennas by screen-printing onto NC-coated paper, demonstrating to be operative.

Prevention Method of Electromagnetic Interference by Implementing NFC Radio Active Signal for Touchpad

This paper reviews the patented control method of preventing the electromangnetic interference from NFC antenna to touchpad sense lines efficirntly. The NFC antenna was integrated under the touchpad by implementing NFC_radio_active signal from the NFC module to the touchpad sensor controller IC. The conventional control method required fine-tuning of the touchpad sensor firmware was required to detect and learn the NFC antenna trace in order to prevent this electromagnetic interference.

High-efficiency and compact WPT receiving antenna design using simulation optimization method

In this paper, a high-efficiency and compact wireless power transfer (WPT) receiving antenna using an flexible printed circuits board (FPCB) with high-Q factor is proposed. The proposed high-efficiency and compact WPT receiving antenna consists of a spiral structure, a lumped element and via through the ground structure. In this paper, in order to design a miniaturized high-efficiency WPT receiving antenna, machine learning technology was used to optimally design the antenna pattern that affects the Q factor. The designed receiving antenna has improved wireless power transmission efficiency with high Q characteristics. The power transfer efficiency is above 88% from distance 10 mm and the resonant frequency is 110 MHz. The sizes of the receiving antenna and the NFC antenna are 30 × 40 mm and 20 × 30 mm, respectively. Machine learning was used to design and fabricate the composite module of a WPT receiving antenna and NFC antenna. Comparison of the experimental results of the proposed receiving antenna with a general receiving antenna confirms the improvement in transmission efficiency.

Effects on human body and conductive body over a near field communication antenna

ABSTRACT The paper presents an NFC antenna based on a rectangular spiral examining the effect of the geometry and the addition of a ferrite sheet. Several prototypes are fabricated and tested where the influence of a human wrist and a conducting body close to the antenna are studied.

Electronic-components less fully textile multiple resonant combiners for body-centric near field communication

Smart and e-textiles have nowadays an important increasing place in the garment industry. The rise of embedded telecommunications, especially smartphones in our pocket, enables us to provide a power source and a wireless link for smart textiles. The main issue is to develop garments able to receive power from smartphones and communicate with them without flexibility and comfort constraints bound to embedded solid-state electronic components. Consequently, this article aims to develop a fully textile NFC combiner to transfer data and power between a smartphone and sensors without any electronic components. It precisely describes textile NFC multiple combiners composed of textile NFC antennas linked by two-wire transmission lines. Also, theoretical analysis, simulations, and experiments have been conducted to adapt the resonant frequency of such structures to the NFC technology (13.56 MHz). Finally, our article generalizes textile NFC combiner resonant frequency equations for multiple combiners with any number of antennas.

Versatile fabrication of liquid metal nano-ink based flexible electronic devices

Liquid metal (LM) of eutectic Gallium-Indium (EGaIn) possesses room temperature fluidity and excellent conductivity, allowing for promising potentials in flexible electronics. However, it is a considerable challenge to fabricate LM based circuits due to high surface tension of EGaIn. Here, we present a polyvinylpyrrolidone (PVP) stabilized LM nano-ink with excellent colloidal stability can be employed for constructing flexible devices by versatile fabrication strategies. By direct-writing, the circuits can be fabricated on common paper, followed by mechanical sintered to recover conductivity. The circuits can be then enveloped by temperature-controlled roll laminator for its practical durability. By filtration, LM nanodroplets were sucked into the porous structure of a Nylon film to form conductive membrane, which could restore conductive property by friction sintering. Subsequently, customized conductive pattern readily obtained by laser cutting could be encapsulated in flexible material of Ecoflex, yielding different flexible devices including NFC antenna, capacitor based pressure sensor and bio-electrodes for nerve signal sensing of living mice in vivo. The current work presents versatile fabrication strategies of LM nano-ink based flexible electronics, which hold great possibilities in the field of printed electronics. Furthermore, the LM nano-ink that reconciles stability and biocompatibility provides huge potential for future implanted flexible electronics.

Textile NFC antenna for power and data transmission across clothes

In this article, it is shown how a smartphone can be used together with an e-textile structure, such as smart clothing, or any other smart home textile structure, smart composite, etc, to power it and to send and receive data generated by the e-textile by using the magnetic induction phenomenon through textile materials. This has been achieved using the NFC communication protocol and NFC compatible fully textile antennas without any electronic components such as resistors, inductors or capacitors. Our NFC antennas have been realized by embroidery and geometrical shapes using conductive threads. All the antennas realized have been tested to show their capacity to send the power and to send and receive data from sensors, in particular by testing their resonant frequencies, which are 13.7 MHz and 13.83 MHz, and their quality factor, which are 45 and 55, respectively. The approach used in this work facilitates the design and production of smart textiles and their reliability and washability, as they do not need any more to be equipped with power supplies such as batteries and data acquisition and interface cards, that are not laundering and cleaning friendly and are very difficult to be realized on flexible structures making them textile compatible. Therefore, we believe that in the future, a smartphone placed in specific locations in our clothing (pockets) equipped with our antennas will help the development and the market readiness of future generations of smart textile structures. The realized prototypes will enable to create a sensor network by acting as a current extension transmitting power and data.

An NFC-CPT-Combined Coupler With Series- None Compensation for Metal-Cover Smartphone Applications

A near-field communication capacitive power transfer (NFC-CPT)-combined coupler with a series-none compensation topology is proposed for metal-cover smartphone applications. To achieve capacitive power transfer through metal cover, the metal cover itself is used as the receiving metal plates. To realize NFC through metal cover, the cross slot including a slim horizontal slot and a rectangular slot is embedded on the metal cover, which mitigates the eddy current loss and increases the inductive coupling for the NFC antenna. Besides, the cross slot divides the metal cover into two separate metal plates, which is necessary for capacitive power transfer. Considering the space limitation and safety requirement, no compensation components are integrated inside the smartphone and only a series inductance is integrated on the transmitter side. A prototype of the proposed NFC-CPT-combined coupler has been built. The wireless power transfer and NFC through metal cover have been validated through experiment. The experimental results show that the prototype achieves 5-W output power with a 93.5% circuit efficiency at 6.78 MHz, and the detection range of the NFC antenna is 61 mm.

A Smart Food Label Utilizing Roll-to-Roll Gravure Printed NFC Antenna and Thermistor to Replace Existing “Use-By” Date System

The current system of assessing food quality via “use-by” dates needs to be replaced by a real-time assessment to prevent blind disposal of consumable food products. Time-temperature history (TTH) based wireless food label, which can wirelessly provide real-time food safety information to the consumer via smartphone, is a viable alternative to the “use-by” dates. However, the cost of wireless TTH-food label has been a major bottleneck in their universal application, especially regarding low-cost, large-quantity products. In addition, such labels should be robust enough to combat external debilitating factors associated with the cold chain system. To overcome these issues, a roll-to-roll (R2R) gravure was exploited to continuously print the wireless TTH-food label platform, in which an NFC antenna and thermistor were realized via all-R2R gravure printing. Then, a Si-chip transponder with an inbuilt microcontroller and R2R printed battery were simply bridged. The resulting wireless TTH-food label thus demonstrated a real-time quality assessment by examining the growth level of foodborne pathogens computed via wirelessly transmitted TTH data to the big data server system.

Flexible Microsystems Using Over-molding Technology

Today’s world is full of intelligent electronics and with the development of flexible printed electronics technologies, different integration approaches are of high demand. The combination of electronics with polymer is a new technology platform as it integrates multiple functionalities into plastic products. This work shows preliminary results in the integration of electronic components (e.g. NFC chips and LEDs) using over-molding technology. A significant degree of freedom in product design is obtained resulting in a low-cost fabrication of flexible smart objects. The integration is achieved by using adhesion between flexible circuits and injection molded plastics. In order to check the adhesion performance between the flexible circuit and polymer injected, the polyimide foils with patterned copper cladding were over-molded with different engineering plastics into the form of peel test specimens. The technology was shown by the realization of a demonstrator, in which LEDs are wirelessly powered using an NFC antenna and a chip. The NFC antenna is executed in the copper layer and the LEDs and NFC chip are soldered on the foil. The antenna and NFC chip can harvest the energy from (e.g. a smartphone) in order to power the LEDs. This is a simple example of wireless energy transfer that could be used to power circuits and readout sensor values using NFC without the need of having an integrated battery.

Proving the robustness of a PEDOT:PSS-based thermistor via functionalized graphene oxide-poly(vinylidene fluoride) composite encapsulation for food logistics.

The instability of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) under a humid condition is the major limitation in the practical development of a flexible thermistor. Here, we introduced a functionalized graphene oxide–polyvinylidene fluoride (FGO–PVDF) composite as an encapsulation layer to prove the reliability of PEDOT:PSS thermistors under high-humidity conditions. The FGO–PVDF-encapsulated thermistor exhibited good linearity, a resolution of 1272.57 Ω per °C, a temperature coefficient of resistance equal to −3.95 × 10−3 per °C, stable performance, and an acceptable response time (∼40 s per °C) calibrated in the temperature range between −10 °C and 30 °C, resembling the temperature of a cold chain system. For applications in a food cold chain system, this thermistor was integrated into a roll-to-roll (R2R) gravure-printed NFC antenna, a microcontroller-embedded Si-chip transponder, and a printed battery to work as a smart label to wirelessly monitor the time–temperature history (TTH) of a food package. A proof-of-concept study was demonstrated by attaching an NFC-enabled hybrid TTH logger, a smart label, in a chicken package.

Design of a wearable bio-patch for monitoring patient's temperature.

New communication technologies allow us developing useful and more practical medical applications, in particular for ambulatory monitoring. NFC communication has the advantages of low powering and low influence range area, what makes this technology suitable for health applications. This work presents an explanation of the design process of planar NFC antennas in a wearable biopatch. The problem of optimizing the communication distance is addressed. Design of a biopatch for continuous temperature monitoring and experimental results obtained wearing this biopatch during daily activities are presented.

Impedance Matching for 13.56 MHz NFC Antennas without VNA

This paper introduces a method of impedance matching for 13.56 MHz NFC antennas without Vector Network Analyzer (VNA). A LCR meter is used to measure resistance and inductance of antennas instead. A three components match is adopted to realize 50- antenna impedance. Both antenna on board and external antenna are designed with rectangular planar spiral copper. They are tested and compared with each other. The results show that two antennas can work well. External antenna has better performance than one on board.