The mode of operation of RFID systems is simple. The RFID tag, which contains the identification data of the object to which it is attached, generates a radio frequency signal with said data. This signal can be captured by an RFID reader, which is responsible for reading the information and passing it in digital format to the specific application that uses RFID 666.

An RFID system consists of the following three components:.

Contenido

Las etiquetas RFID pueden ser activas, semipasivas (también conocidos como semiactivos o asistidos por batería) o pasivos. Las etiquetas pasivas no requieren ninguna fuente de alimentación interna y son dispositivos puramente pasivos (solo se activan cuando un lector se encuentra cerca para suministrarles la energía necesaria). Los otros dos tipos necesitan alimentación, típicamente una pila "Pila (electricidad)") pequeña.

La gran mayoría de las etiquetas RFID son pasivas, que son mucho más baratas de fabricar y no necesitan batería. En 2004, estas etiquetas tenían un precio desde 0.40 $, en grandes pedidos, para etiquetas inteligentes, según el formato, y de 0.95 $ para etiquetas rígidas usados frecuentemente en el sector textil encapsulados en PP o epoxi. El mercado de RFID universal de productos individuales será comercialmente viable con volúmenes muy grandes de 10 000 millones de unidades al año, llevando el coste de producción a menos de 0.05 $ según un fabricante. La demanda actual de chips de circuitos integrados con RFID no está cerca de soportar ese coste. Los analistas de las compañías independientes de investigación como Gartner and Forrester Research convienen en que un nivel de precio de menos de 0.10 $ (con un volumen de producción de 1 000 millones de unidades) solo se puede lograr en unos 6 u 8 años,[9]​ lo que limita los planes a corto plazo para una adopción extensa de las etiquetas RFID pasivas. Otros analistas creen que esos precios serían alcanzables dentro de 10 a 15 años.

A pesar de que las ventajas en cuanto al coste de las etiquetas RFID pasivas con respecto a las activas son significativas, otros factores, incluyendo exactitud, funcionamiento en ciertos ambientes como cerca del agua o metal, y fiabilidad, hacen que el uso de etiquetas activas sea muy común hoy en día.

Para comunicarse, las etiquetas responden a peticiones o preguntas generando señales que a su vez no deben interferir con las transmisiones del lector, ya que las señales que llegan de las etiquetas pueden ser muy débiles y han de poder distinguirse. Además de la reflexión o backscatter, puede manipularse el campo magnético del lector por medio de técnicas de modulación de carga"). El backscatter se usa típicamente en el campo lejano") y la modulación de carga en el campo próximo") (a distancias de unas pocas veces la longitud de onda del lector).

Passive tags

Passive tags do not have electrical power. The signal that reaches them from the readers induces a small electrical current sufficient to operate the CMOS integrated circuit of the tag, so that it can generate and transmit a response. Most passive tags use backscatter on the received carrier; That is, the antenna must be designed to obtain the energy necessary to operate at the same time as transmitting the response by backscatter. This response can be any type of information, not just an identifier code. A tag may include non-volatile, possibly writable memory (e.g. EEPROM).

Passive labels usually have distances of practical use between 10 cm (ISO 14443) and reaching up to a few meters (EPC and ISO 18000-6"), depending on the operating frequency and the design and size of the antenna. Due to their conceptual simplicity, they are obtainable through a printing process of the antennas. As they do not require power supply, the device can be very small: they can be included in a sticker or inserted under the skin (low frequency tags).

In 2006, Hitachi developed a passive device called µ-Chip with a size of 0.15 × 0.15 mm without antenna, thinner than a sheet of paper (7.5 µm).[10]​[11]​ SOI (Silicon-on-Insulator) is used to achieve this integration. This chip can transmit a unique 128-bit identifier fixed to it at manufacture, which cannot be modified and confers authenticity to it. It has a maximum reading range of 30 cm. In February 2007 Hitachi presented a device even smaller than 0.05x0.05 mm and thin enough to be embedded in a sheet of paper.[12] These chips have storage capacity and can operate at distances of up to a few hundred meters. Its main drawback is that its antenna must be at least 80 times larger than the chip.

Alien Technology") (Fluidic Self Assembly), SmartCode") (Flexible Area Synchronized Transfer) and Symbol Technologies (PICA) claim to have processes in various stages of development that can further reduce costs through parallel manufacturing processes. These means of production could further reduce costs and drive the economies of scale models of an important sector of silicon manufacturing. This could lead to further expansion of passive tag technology.

There are labels made with polymer-based semiconductors developed by companies around the world. In 2005 PolyIC and Philips introduced simple tags in the 13.56 MHz range that used this technology. If successfully introduced to the market, these labels would be printable like a magazine, with much lower production costs than silicon labels, serving as a fully printed alternative, like current barcodes. However, this requires that they overcome technical and economic aspects, taking into account that silicon is a technology that has been enjoying multimillion-dollar development investments for decades that have resulted in a lower cost than that of conventional printing.

Due to power and cost concerns, the response of a passive RFID tag is necessarily brief, typically just a single identification number (GUID). The lack of its own power source means the device can be quite small: there are commercially available products that can be inserted under the skin. In practice, passive tags have reading distances that vary from about 10 millimeters to about 6 meters, depending on the size of the tag's antenna and the power and frequency at which the reader operates. In 2007, the smallest commercially available device of this type measured 0.05 millimeters × 0.05 millimeters, and thinner than a sheet of paper; These devices are practically invisible.

Active tags

Unlike passive tags, active tags have their own autonomous energy source, which they use to power their integrated circuits and propagate their signal to the reader. These are much more reliable (have fewer errors) than passive ones due to their ability to establish sessions with the reader. Thanks to their energy source, they are capable of transmitting more powerful signals than passive ones, which makes them more efficient in environments that are difficult for radiofrequency such as water (including humans and livestock, mostly made up of water), metal (containers, vehicles). They are also effective at greater distances and can generate clear responses from weak receptions (unlike passive receptions). On the contrary, they tend to be larger and more expensive, and their useful life is generally much shorter.

Many active tags have effective ranges of hundreds of meters and battery life of up to 10 years. Some of them integrate temperature recording sensors and other variables that can be used to monitor food environments or pharmaceutical products. Other sensors associated with RFID include humidity, vibration, light, radiation, temperature, and atmospheric components such as ethylene. In addition to much greater range (500 m), they have greater storage capacities and the ability to store additional information sent by the transceiver.

Currently, the smallest active tags are about the size of a coin. Many active tags have practical ranges of ten meters, and battery life of up to several years.

Characteristics

The main advantage of active RFID tags over passive ones is the high reading range, on the order of tens of meters. As disadvantages, it is worth highlighting the price, which is much higher than the passive ones, and the dependence on battery power. The lifespan of the batteries depends on each label model and also on its activity; it is normally on the order of years. To facilitate battery management, it is common for active RFID tags to send battery level information to the reader, allowing those that are about to run out to be replaced in advance.

These batteries provide the tags with power in standby mode in which the current consumed is very small (generally 3uA) and in operating mode (where 24mA is consumed) these batteries can last from 1 to 10 years, which makes them more robust. The most used are lithium and manganese dioxide such as CR2032 and CR2320. Below are its technical characteristics:

It has the following dimensions according to IEC 60086:.

The discharge performance based on temperature and load resistance is shown in the following graphs:

There are also ultra-thin printed batteries for active packaging design. These batteries are flexible, powerful and less than a millimeter thick, making them ideal for active tags in RFID systems.

Another alternative is paper batteries, which have applications in RFID devices, smart cards and paper LEDs, among others. It is a battery that is made up of thin sheets of chemical compounds embedded in paper, obtaining electrical energy from oxidation-reduction reactions, producing at the terminals a nominal voltage of 1.5 V and a charge of approximately 1.5 mAh.

Semi-passive tags

Semi-passive tags are similar to active tags in that they have their own power supply, although in this case it is mainly used to power the microchip and not to transmit a signal. The energy contained in the radio frequency is reflected towards the reader as in a passive tag. An alternative use for the battery is to store information propagated from the reader to emit a response in the future, typically using backscatter. Batteryless tags must respond by reflecting carrier power from the reader on the fly.

The battery can allow the tag's integrated circuit to be constantly powered and eliminate the need to design an antenna to collect power from an incoming signal. Therefore, antennas can be optimized to use backscattering methods. Semi-passive RFID tags respond faster, so they are stronger in read rate" than passive ones.

This type of tag has a reliability comparable to that of active tags, while being able to maintain the operating range of a passive one. They also tend to last longer than active ones.

What are the differences between barcode and RFID tags?.

One of the essential functions of security seals is to guarantee the correct identification and traceability of the products and merchandise to which they are associated. What are the differences between barcode and RFID tags? The security seal then functions as a vehicle of information thanks to the codes that are integrated into it.

The main differences between identification systems: What are the differences between barcode and RFID tags?

It is interesting to compare more traditional systems such as barcodes against the alternative presented by RFID tags. Let's review the behavior of each one focusing on four main characteristics:.

Information storage capacity.

Versatility and scanning speed.

System cost.

Outstanding advantage.

1. Bar code.

The outstanding advantage of the barcode is its standardization in a multitude of sectors. The simplicity of its use and its correct level of precision make it the most widespread system in the retail or commerce sector and in inventory and logistics management.

However, its information storage capacity is more limited by space: it records up to 20 characters. On the other hand, barcode scanning requires human intervention and direct contact of the reader with the printed information, something that slows down the process.

Regarding cost, barcodes can be printed with simple systems and therefore are not burdensome, but it is true that they are more prone to deterioration in aggressive environments and cannot be modified once they have been printed.

2. RFID tags.

Antenna Types

The type of antenna used in a tag depends on the application for which it is designed and the frequency of operation. Low frequency or LF tags normally use electromagnetic induction. Since the induced voltage is proportional to the frequency, the voltage needed to power an integrated circuit can be produced using a sufficient number of turns. There are compact LF tags (such as those encapsulated in glass, used for human and animal identification) that use an antenna in several levels (three of 100-150 turns each) around a ferrite core "Ferrite (ferromagnetic ceramic)").

At high frequency (HF, 13.56 MHz) a flat spiral with 5 to 7 turns and a form factor similar to that of a credit card is used to achieve distances of tens of centimeters. These antennas are cheaper than LF antennas since they can be produced by means of lithography instead of spiration, although two metal surfaces and one insulator are necessary to make the cross connection from the outer level to the inside of the spiral, where the resonance capacitor and the integrated circuit are located.

Passive ultra-high frequency (UHF) and microwave tags are usually radio-coupled to the reader's antenna and use classic dipole antennas "Dipole (antenna)"). Only one layer of metal is necessary, which reduces cost. Dipole antennas, however, do not fit very well with the characteristics of typical integrated circuits (high input impedance, slightly capacitive). Folded dipoles or short loops can be used as complementary inductive structures to improve power supply. Half-wave dipoles (16 cm at 900 MHz) are too large for most applications (e.g. RFID tags for label use cannot be larger than 10 cm), so antennas must be doubled to meet size needs. Broadband structures can also be used. The gain "Gain (electronic)") of compact antennas is usually lower than that of a dipole (less than 2 dB) and they can be considered isotropic in the plane perpendicular to their axis.

Dipoles undergo coupling with radiation that is polarized on their axes, so the visibility of a tag with a single dipole antenna depends on its orientation. Tags with two octagonal antennas (double dipole tags) are much less dependent on it and the polarization of the reader's antenna, but are typically larger and more expensive than their single counterparts.

Patch antennas can be used to provide service in the vicinity of metal surfaces, although a thickness of 3 to 6 mm is necessary to achieve good bandwidth, in addition to having a ground connection which increases the cost compared to simpler single layer structures.

HF and UHF antennas are usually made of copper or aluminum. Conductive inks have been tested on some antennas, finding problems with adhesion to the integrated circuit and stability of the environment.

Tag association

There are three basic types of labels due to their relationship with the objects they identify: associable, implantable and insertable (attachable, implantable, insertion).[13] In addition to these types of labels, Eastman Kodak has filed two patent applications that deal with monitoring the consumption of medicine in the form of a “digestible” label.[14]​.

Label positioning

Orientation can affect the performance of UHF tags through the air. In general, optimal reader power reception is not necessary to operate passive tags. However, there may be cases in which the distance between both parts is fixed as well as the effective power emitted. In this case, it is necessary to know in which cases you can work optimally with them.

The points called R (resonance spot*), L (live spot*) and D (dead spot*) are defined to specify the location of the tags on a marked object, so that they can still receive the necessary energy based on certain levels of emitted power and distance.[15]​.

Tag environments

The concept of the RFID tag is associated with its ubiquity. This means that readers may require the selection of tags to be explored from among many possible candidates. They may also want to scan tags in their environment to take inventory or, if the tags are associated with sensors and can maintain their values, identify environmental conditions. If an RFID reader tries to work with a set of tags, it must know the devices that are in its area of ​​action and then go through them one by one, or use collision avoidance protocols.

To read the data from the tags, the readers use a singulation algorithm based on tree traversal, resolving any collisions that may occur and sequentially processing the responses. There are blocking tags that can be used to prevent readers from accessing the tags in an area without resorting to suicide commands to disable them. These masquerade as normal labels but have certain specific characteristics; Specifically, they can take any identification code as their own, and can answer any questions they hear, securing the environment by nullifying the usefulness of these questions.

In general, a spurious signal can be emitted if tag activity is detected to block weak tag transmissions. If the labels are expendable or are not needed again, they can be rendered useless by inducing high currents in them that render their circuits useless.

Apart from this, a tag can be promiscuous, if it responds to all requests without exception, or secure, if it requires authentication (this involves the typical aspects of cryptographic and access key management). A tag can be set to activate or deactivate in response to commands from the reader.

Readers in charge of a group of tags in an area can operate in autonomous mode, as opposed to interactive mode. Working this way, they perform periodic identification of all tags in their environment and maintain a presence list with timeouts and control information. If an entry expires, it is removed from the table.

Often a distributed application requires the use of both extreme types of tags. Passive ones cannot perform continuous monitoring tasks, but instead perform tasks on demand when readers request them. They are useful for carrying out regular and well-defined activities with limited storage and security needs. If there are frequent, continuous or unpredictable accesses, or there are real-time or data processing requirements (such as searching internal tables), it is usually convenient to use active tags.

RFID systems are classified depending on the frequency range they use. There are four types of systems: low frequency (LF: 125 or 134.2 kHz); high frequency (HF: 13.56 MHz); ultra-high frequency (UHF: 868 to 956 MHz); and microwave (2.45 gigahertz). UHF systems cannot be used worldwide because there is no single global regulation for their use.

RFID standards address four fundamental areas:

As in other technological areas, standardization in the field of RFID is characterized by the existence of several groups of competing specifications. On the one hand there is ISO, and on the other Auto-ID Center (known since October 2003 as EPCglobal,[16]​ from EPC, Electronic Product Code). Both share the objective of achieving low-cost tags that operate in UHF.

EPC standards for labels are of two kinds:

The classes are not interoperable and are also incompatible with ISO standards. Although EPCglobal") is developing a new generation of EPC standards (called Gen2), with the aim of achieving interoperability with ISO standards, the 8-bit AFI (Application Family Identifier) ​​is still under discussion.

For its part, ISO has developed RFID standards for automatic identification and object management. There are several related standards, such as ISO 10536", ISO 14443 and ISO 15693, but the series of standards strictly related to RFID and the frequencies used in such systems is the 18000 series.

There is no global public corporation that governs the frequencies used for RFID. In principle, each country can set its own rules.

The main corporations that govern the assignment of frequencies for RFID are:

Although the legislation of the radio frequency spectrum is under the sovereignty of each country, there are international organizations that are responsible for establishing uses and recommendations for each band of the electromagnetic spectrum, such as the ITU-R. Most national spectrum legislation bodies are part of the ITU-R regulatory committees and in turn follow the recommendations proposed by this body. You can obtain more information about this body's recommendations regarding RFID systems in its report on the matter.

Low frequency (LF: 125 - 134 kHz and 140 - 148.5 kHz) and high frequency (HF: 13.56 MHz) RFID tags can be used globally without the need for a license. The ultra-high frequency (UHF: 868 - 928 MHz) cannot be used globally, since there is no single global standard. In North America, UHF can be used without a license for frequencies between 908 - 928 MHz, but there are restrictions on transmission power. In Europe ultra-high frequency is under consideration for 865.6 - 867.6 MHz. Its use is license-free only for the range 869.40 - 869.65 MHz, but there are restrictions on transmission power. The US UHF standard (908-928 MHz) is not accepted in France and Italy as it interferes with their military bands. In China and Japan there is no regulation for the use of ultra-high frequency. Each UHF application in these countries requires a license, which must be requested from local authorities, and can be revoked. In Australia and New Zealand the range is 918 - 926 MHz for unlicensed use, but there are restrictions on transmit power.

There are additional regulations related to health and environmental conditions. For example, in Europe, the Waste Electrical and Electronic Equipment regulation does not allow RFID tags to be discarded. This means that RFID tags on cardboard boxes must be removed before disposal. There are also additional regulations regarding health; see electromagnetic field.

Dependiendo de las frecuencias utilizadas en los sistemas RFID, el coste, el alcance y las aplicaciones son diferentes. Los sistemas que emplean frecuencias bajas tienen igualmente costes bajos, pero también baja distancia de uso. Los que emplean frecuencias más altas proporcionan distancias mayores de lectura y velocidades de lectura más rápidas. Así, las de baja frecuencia se utilizan comúnmente para la identificación de animales, seguimiento de barricas de cerveza, o como llave de automóviles con sistema antirrobo"). En ocasiones se insertan en pequeños chips en mascotas, para que puedan ser devueltas a su dueño en caso de pérdida. En los Estados Unidos se utilizan dos frecuencias para RFID: 125 kHz (el estándar original) y 134.5 kHz (el estándar internacional). En Argentina también se utiliza la frecuencia de 125 kHz para las tarjetas plásticas de proximidad de baja frecuencia, aunque también se comercializan modelos de alta frecuencia de 13.56 MHz más versátiles, que permiten operaciones de lectura / escritura y realizar varias aplicaciones al mismo tiempo. Las etiquetas RFID de alta frecuencia se utilizan en bibliotecas y seguimiento de libros, seguimiento de palés, control de acceso en edificios, seguimiento de equipaje en aerolíneas, seguimiento de artículos de ropa y últimamente en pacientes de centros hospitalarios para hacer un seguimiento de su historia clínica. Un uso extendido de las etiquetas de alta frecuencia como identificación de acreditaciones, substituyendo a las anteriores tarjetas de banda magnética. Solo es necesario acercar estas insignias a un lector para autenticar al portador.

Las etiquetas RFID de UHF se utilizan comúnmente de forma comercial en seguimiento de palés y envases, y seguimiento de camiones y remolques en envíos o en sistemas de distribución de uniformidad en hospitales HF(Asturias - España) o incluso en la ropa plana, siempre y cuando la etiqueta sea encapsulada en resina de epoxi, para mayor resistencia al proceso de calandrado y prenda de extracción de agua.

Las etiquetas RFID de microondas se utilizan en el control de acceso en vehículos de gama alta.

Algunas autopistas, como por ejemplo el carril de telepeaje IAVE en las autopistas de CAPUFE en México la FasTrak de California, el sistema I-Pass de Illinois, el telepeaje TAG en las autopistas urbanas en Santiago de Chile, la totalidad de las autopistas pagas argentinas y el E-Pass de Filipinas utilizan etiquetas RFID para recaudación con peaje electrónico"). Las tarjetas son leídas mientras los vehículos pasan; la información se utiliza para cobrar el peaje en una cuenta periódica o descontarla de una cuenta prepago. El sistema ayuda a disminuir el entorpecimiento del tráfico causado por las cabinas de peaje.[18]​.

Sensores como los sísmicos pueden ser leídos empleando transmisores-receptores RFID, simplificando enormemente la recolección de datos remotos.

En enero de 2003, Michelin anunció que había comenzado a probar transmisores-receptores RFID insertados en neumáticos. Después de un período de prueba estimado de 18 meses, el fabricante ofrecerá neumáticos con RFID a los fabricantes de automóviles. Su principal objetivo es el seguimiento de neumáticos en cumplimiento con la United States Transportation, Recall, Enhancement, Accountability and Documentation Act (TREAD).

Las tarjetas con chips RFID integrados se usan ampliamente como dinero electrónico, como por ejemplo la tarjeta Octopus en Hong Kong, tarjeta bip! en Santiago de Chile para el transporte público (Transantiago), la tarjeta SUBE para el transporte de Argentina (metro y buses, especialmente en la Ciudad Autónoma de Buenos Aires), la tarjeta prepago del Sistema Integrado Guatemalteco de Autobuses para uso en el Transurbano y en el Transmetro (Guatemala) "Transmetro (Guatemala)") en Guatemala, Sistema Integrado de Transporte y Transmilenio en Bogotá Colombia, prepago en cinemas Tarjeta Cineco") la tarjeta Cívica en Medellín, y en las tarjetas para el Bus Metropolitano "Metropolitano (Lima)") que opera desde 2010 en Lima, Perú.

Comenzando con el modelo de 2004, está disponible una "llave inteligente" como opción en el Toyota Prius y algunos modelos de Lexus. La llave emplea un circuito de RFID activo que permite que el automóvil reconozca la presencia de la llave a un metro del sensor. El conductor puede abrir las puertas y arrancar el automóvil mientras la llave sigue estando en la cartera o en el bolsillo.

En agosto de 2004, el Departamento de Rehabilitación y Corrección de Ohio (ODRH) aprobó un contrato de 415.000 dólares para ensayar la tecnología de seguimiento con Alanco Technologies"). Los internos tienen unos transmisores del tamaño de un reloj de muñeca que pueden detectar si los presos han estado intentando quitárselas y enviar una alarma a los ordenadores de la prisión. Este proyecto no es el primero que trabaja en el desarrollo de chips de seguimiento en prisiones estadounidenses. Instalaciones en Míchigan, California e Illinois emplean ya esta tecnología.

En abril de 2016 el Club Atlético Tigre de Argentina inició una campaña para que sus hinchas se inyecten un chip con RFID dentro de su cuerpo para controlar su acceso a la cancha. El proyecto de biohacking fue considerado totalmente innovador como extraordinario, generando controversia y desacuerdo por parte de la población, aunque su uso no se piensa como obligatorio sino como alternativo al carnet utilizado usualmente.[19]​.

Libraries

Some libraries use RFID tags to replace barcodes due to their many advantages. These tags can contain information to identify each item within the library and even its usage history. RFID tags can serve as a method of inventory management and also offer self-service to users, so they can return books at any time of the day or night. Book labels can be read while the books are moving on a conveyor belt, reducing staff time. Since RFID tags do not require an optical reader, there is no need to open a book cover or DVD case to scan the item, which is why a stack of books can be read at the same time. Thanks to this, the tags can also serve as a security device with the help of a pair of antennas at the exit of the library. Likewise, with portable readers, library managers can do inventory control on an entire shelf in a matter of seconds.[20]​.

Textile-health sector

Currently, the costs of textile RFID have been significantly reduced, reaching around €0.50 to €0.55. The most resistant are encapsulated in epoxy resin, which are also suitable for automatic garment distribution systems (closets, lockers or hanger systems).[21]​.

These can be inserted into garments very discreetly, inside the hems, heat-sealed or simply sewn.

The ideal is the correct one inserted in the garments, since the position is very important since if it is placed in certain areas, it can cause errors in the reading. The importance of reading quality is fundamental. Having previously selected the hardware, antennas and readers, as well as being located in a non-metallic or properly insulated environment is crucial to achieving 100% reading. Nowadays, thanks to the anti-collision protocol, dozens of garments or objects can be read en masse without the need for direct visibility or without the need to remove the garments from laundry bags, boxes or plastic in just a few seconds.

Thanks to this product in the textile sector, laundry, lingerie and automatic clothing dispensing processes in sectors such as healthcare or fashion, the optimization of human resources and a very important stock reduction of up to 35% in direct inventory and a reduction of up to 50% in the loss, misplacement or theft of garments is achieved. Elements such as reading tunnels are devices that help the user of these systems very precisely, reaching 100% reading.

In Spain, the rise of this technology is clearly growing, although there are very few companies that can offer guarantees of success in the implementation and advice of the devices to use, always HF. In June 2014, the Inditex Group signed an important agreement with Tyco[22]​ to improve inventory processes and reduce unknown loss and theft. With this, the retailer optimizes its investment in inventory and maximizes sales and margins. It is important for a good technological partner in this field to be able to perfectly size the system.[23]​.

In the case of flat clothing, its use is highly conditioned to the selected label, being the most important part to ensure the correct functioning of said garments. Labels encapsulated in epoxy resin have proven to be the only ones resistant to demanding washing processes, where garments are used to extract excess water after the car wash and resistant to calendering, which due to the pressures exerted on the clothes, up to 9 bars, although it is advisable to reduce it to 3 bars (sufficient to secure the fabric), and the high drying temperature up to 180 °C. If its use is required on this clothing, the epoxy encapsulated label is the most recommended, since other flat cotton or plastic label solutions end up breaking or melting, with the consequent detriment to the project. There are several companies that are experts in this type of label, although TagsysRfid is the one that can provide the most experience, due to the large number of references in the textile-health sector. The Fujitsu company has recently developed WT-A522 labels with a non-metallic antenna with the capacity to be used in MRI environments, and to massively read more than 500 garments in just a few seconds, allowing total traceability of all hospital flat clothing.

Logistics[25][26]​

Currently, the most important application of RFID is logistics. The use of this technology would allow any product to be located within the supply chain. In relation to traceability, labels could have great application since they can be recorded, which would allow us to know how long the product was stored, in which locations, etc. In this way, important optimizations can be achieved in the management of products in supply chains based on the same product, and becoming practically independent of the information system.

Due to the size of these two organizations, their RFID mandates have impacted thousands of companies around the world. The deadline has been extended several times because many manufacturers face great difficulties in implementing RFID systems. In practice, successful reading numbers are currently at 80%, due to radio wave attenuation caused by products and packaging. Soon it is expected that even the smallest companies will be able to put RFID tags on their transport.

Since January 2005, Walmart required its top 100 suppliers to apply RFID tags to all of their shipments. In order to meet the requirement, manufacturers use RFID encoders/printers to label boxes and pallets that require EPC labels for Walmart. These smart labels are produced by integrating the RFID into the label material, and printing the barcode and other visible information on the surface of the label.

human implants

Implantable RFID chips, originally designed for animal tagging, are being used and are being considered for humans as well. Applied Digital Solutions" proposes its unique under-the-skin format chip as a solution to identity theft, secure building access, computer access, medical record storage, anti-kidnapping initiatives and a variety of applications. Combined with sensors to monitor various body functions, the Digital Angel device could provide patient monitoring. The Baja Beach Club in Barcelona (Spain) uses an implantable Verichip to identify its VIP customers, who use it to pay for drinks. The Mexico City police department has implanted the Verichip in about 170 of its police officers, to allow access to police databases and to be able to track them if they are kidnapped.

Marketing/Events Sector

Nowadays RFID has been used to control visitors at events and recreational parks. This has made it possible to connect social networks with RFID. Events like CES in Las Vegas, NV and others have brought a lot of attention to potential new industries. RFID is already used as an electronic wallet method to make payments within amusement parks [1]. This shows a great advance of the RFiD system trying to take the use of the magnetic stripe.

Las etiquetas RFID se ven como una alternativa que reemplazará a los códigos de barras UPC o EAN, puesto que tienen un número de ventajas importantes sobre la arcaica tecnología de código de barras. Quizás no logren sustituir en su totalidad a los códigos de barras, debidos en parte a su costo relativamente más alto. Para algunos artículos con un coste más bajo la capacidad de cada etiqueta de ser única se puede considerar exagerado, aunque tendría algunas ventajas tales como una mayor facilidad para llevar a cabo inventarios.

También se debe reconocer que el almacenamiento de los datos asociados al seguimiento de las mercancías a nivel de artículo ocuparía muchos terabytes. Es mucho más probable que las mercancías sean seguidas a nivel de palés usando etiquetas RFID, y a nivel de artículo con producto único, en lugar de códigos de barras únicos por artículo.

Los códigos RFID son tan largos que cada etiqueta RFID puede tener un código único, mientras que los códigos UPC actuales se limitan a un solo código para todos los casos de un producto particular. La unicidad de las etiquetas RFID significa que un producto puede ser seguido individualmente mientras se mueve de lugar en lugar, terminando finalmente en manos del consumidor. Esto puede ayudar a las compañías a combatir el hurto y otras formas de pérdida del producto. También se ha propuesto utilizar RFID para comprobación de almacén desde el punto de venta, y sustituir así al encargado de la caja por un sistema automático que no necesite ninguna captación de códigos de barras. Sin embargo no es probable que esto sea posible sin una reducción significativa en el coste de las etiquetas actuales. Se está llevando a cabo una investigación sobre la tinta que se puede utilizar como etiqueta RFID, que reduciría costes de forma significativa. Sin embargo, faltan todavía algunos años para que esto dé sus frutos.

Gen 2

An organization called EPCglobal is working on an international standard for the use of RFID and EPC in identifying any item in the supply chain for companies in any type of industry, anywhere in the world. The organization's top council includes representatives from EAN International"), Uniform Code Council"), The Gillette Company"), Procter & Gamble, Wal-Mart, Hewlett-Packard, Johnson & Johnson, SATO, and Auto-ID Labs"). Some RFID systems use alternative standards based on the ISO 18000-6 classification.

The EPCglobal gen 2 standard was approved in December 2004, and is likely to form the backbone of RFID tag standards going forward. This was approved after a challenge from Intermec over the possibility that the standard could infringe several of its RFID-related patents. It was decided that the standard itself did not infringe its patents, but that royalties may have to be paid to Intermec if the tag were read in a particular way. EPC Gen2 is the abbreviation of EPCglobal UHF Generation 2.

In June 2006, the ISO adopted the standard under the name ISO/IEC 18000-6C.

Patient identification

In July 2004, the U.S. Food and Drug Administration made public a decision to begin a study process that will determine whether hospitals can use RFID systems to identify patients Hospital La Fe or to allow access by relevant hospital personnel to medical records.") The use of RFID to prevent mixing of sperm and eggs in IVF clinics is also being considered. [2]. Additionally, the FDA recently approved the first U.S. RFID chips that can be implanted in humans. The 134.2 kHz RFID chips, from VeriChip Corp., a subsidiary of Applied Digital Solutions Inc., can incorporate personal medical information and could save lives and limit injuries caused by medical treatment errors, according to the company. disclosed during a conference call with investors. Its application in the home has also been proposed, to allow, for example, a refrigerator to know the expiration dates of the food it contains, but there has been little progress beyond simple prototypes.

Another use in the health sector is the location of clinical records, within a mass environment or decentralized warehouses, that is, in warehouses outside the hospital. Inventory management and location can be greatly improved with incredible results just by putting an RFID chip in them. Furthermore, with mass reading devices, 100% reading of clinical records can be guaranteed and complete traceability can be achieved without problems and in a very simple way.

Traffic and positioning

Another proposed application is the use of RFID for "smart traffic signs" on the road. It is based on the use of RFID transponders buried under the pavement (radio beacons) that are read by an onboard unit (OBU) that filters the various traffic signs and translates them into voice messages or gives a virtual projection using a HUD (Heads-Up Display). Its main advantage compared to satellite-based systems is that Radio beacons do not need digital mapping since they provide the traffic signal symbol and position information by themselves. RFID radio beacons are also useful to complement satellite positioning systems in places such as tunnels or interiors, or in guiding blind people.

El uso de la tecnología RFID ha causado una considerable polémica e incluso boicots de productos. Las cuatro razones principales por las que RFID resulta preocupante en lo que a privacidad se refiere son:.

La mayoría de las preocupaciones giran alrededor del hecho de que las etiquetas RFID puestas en los productos siguen siendo funcionales incluso después de que se hayan comprado los productos y se hayan llevado a casa, y esto puede utilizarse para vigilancia y otros propósitos cuestionables sin relación alguna con sus funciones de inventario en la cadena de suministro. Aunque la intención es emplear etiquetas RFID de corta distancia, estas pueden ser interrogadas a mayores distancias por cualquier persona con una antena de alta ganancia "Ganancia (electrónica)"), permitiendo de forma potencial que el contenido de una casa pueda ser explorado desde cierta distancia. Incluso un escaneado de rango corto es preocupante si todos los artículos detectados aparecen en una base de datos cada vez que una persona pasa un lector, o si se hace de forma malintencionada (por ejemplo, un robo empleando un escáner de mano portátil para obtener una evaluación instantánea de la cantidad de víctimas potenciales). Con números de serie RFID permanentes, un artículo proporciona información inesperada sobre una persona incluso después de su eliminación; por ejemplo, los artículos que se revenden, o se regalan, pueden permitir trazar la red social de una persona.

Otro problema referente a la privacidad es debido al soporte para un protocolo "Protocolo (informática)") de singulation (anticolisión). Esta es la razón por la cual un lector puede enumerar todas las etiquetas que responden a él sin que ellas interfieran entre sí. La estructura de la versión más común de este protocolo es tal que todos los bits del número de serie de la etiqueta salvo el último se pueden deducir por espionaje pasivo a distancia tan solo en la parte del protocolo que afecta al lector. Por esta razón, si las etiquetas RFID están cerca de algún lector, la distancia en la cual la señal de una etiqueta puede ser escuchada es irrelevante. Lo que importa es la distancia a la que un lector de mucho más alcance puede recibir la señal. Independientemente de que esto dependa de la distancia a la que se encuentre el lector y de qué tipo sea, en un caso extremo algunos lectores tienen una salida de energía máxima (4 W) que se podría recibir a diez kilómetros de distancia.

Passports

Several countries have proposed the implementation of RFID devices in new passports, to increase the efficiency of biometric data reading machines. Security expert Bruce Schneier said of these proposals: "It's a clear threat to both personal security and privacy. It's simply a bad idea." Passports with integrated RFID only identify their bearer, and in the proposal being considered, would also include other personal data. This could make some of the abuses of RFID technology just discussed much simpler, and the amount of data could be expanded to include, for example, abuses based on reading a person's nationality. For example, an assault near an airport could target victims who have arrived from wealthy countries, or a terrorist could design a bomb that would work when near people from a particular country.

The United States Department of State initially rejected these hypotheses because they thought that the chips could only be read from a distance of 10 cm, without taking into account more than 2,400 critical comments from security professionals, and a clear demonstration that with special equipment passports can be read from 10 m. [28]​.

Pakistan Passport Authority has started issuing passports with RFID tags.

Driving license

The U.S. state of Virginia has considered putting RFID tags on driver's licenses to make checking faster for police and other officials. The Virginia General Assembly also hopes that by including the tags, it will cost much more to obtain fake IDs. The proposal was first introduced in the Driver's License Modernization Act of 2002, which was not enacted, but in 2004 the concept was still being considered.

The idea was promoted by the fact that several of the 9/11 hijackers had fraudulent Virginia driver's licenses. However, the American Civil Liberties Union said that in addition to being a risk to privacy and freedom, the RFID proposal would not have hindered terrorists, since the false documentation they carried was valid, since they were official documents obtained with another false identification. The weakness of the system is that it does not fail when validating documents at the time, but rather it fails to verify identity before issuing them.

Under the proposal, no information would be stored on the tag except for the number corresponding to the bearer's information in a database, only accessible by authorized personnel. Furthermore, to deter identity fraud") it would only be necessary to wrap a driver's license in aluminum foil. [5].

Faraday shielding as a countermeasure to RFID

A Faraday cage can be used to prevent radio frequency signals from escaping or entering an area, acting as an RF shield.

If an RFID device were surrounded with Faraday shielding, it would have greatly attenuated incoming and outgoing signals, to the point that they would not be usable. A very simple Faraday shield, suitable for most purposes, would be an aluminum foil wrapper. A more effective one would be a copper rectangle around the object. An implanted RFID would be more difficult to neutralize with such shielding, but even a simple aluminum foil covering would attenuate the electric field component of the signals.

Permanently neutralizing the RFID may require a strong alternating electrical current adjacent to the RFID, which overloads the tag and destroys its electronics. In some cases, depending on the composition of the RFID, a strong magnet may serve to mechanically destroy the coil or chip connection by mechanical force exerted on the coil. With the development of RFID technology, other methods may be necessary.

The 125 kHz, 134 kHz (low frequency), and in several cases 13.56 MHz (high frequency) tags are linked by a magnetic field rather than an electric field, called inductive coupling. Since the Faraday cage shields only the electrical component of the electromagnetic field, aluminum foil shielding is ineffective. Any magnetic shielding, such as a thin sheet of iron or steel, encapsulating the tag's antenna coil, will be effective.

The mode of operation of RFID systems is simple. The RFID tag, which contains the identification data of the object to which it is attached, generates a radio frequency signal with said data. This signal can be captured by an RFID reader, which is responsible for reading the information and passing it in digital format to the specific application that uses RFID 666.

An RFID system consists of the following three components:.

Contenido

Las etiquetas RFID pueden ser activas, semipasivas (también conocidos como semiactivos o asistidos por batería) o pasivos. Las etiquetas pasivas no requieren ninguna fuente de alimentación interna y son dispositivos puramente pasivos (solo se activan cuando un lector se encuentra cerca para suministrarles la energía necesaria). Los otros dos tipos necesitan alimentación, típicamente una pila "Pila (electricidad)") pequeña.

La gran mayoría de las etiquetas RFID son pasivas, que son mucho más baratas de fabricar y no necesitan batería. En 2004, estas etiquetas tenían un precio desde 0.40 $, en grandes pedidos, para etiquetas inteligentes, según el formato, y de 0.95 $ para etiquetas rígidas usados frecuentemente en el sector textil encapsulados en PP o epoxi. El mercado de RFID universal de productos individuales será comercialmente viable con volúmenes muy grandes de 10 000 millones de unidades al año, llevando el coste de producción a menos de 0.05 $ según un fabricante. La demanda actual de chips de circuitos integrados con RFID no está cerca de soportar ese coste. Los analistas de las compañías independientes de investigación como Gartner and Forrester Research convienen en que un nivel de precio de menos de 0.10 $ (con un volumen de producción de 1 000 millones de unidades) solo se puede lograr en unos 6 u 8 años,[9]​ lo que limita los planes a corto plazo para una adopción extensa de las etiquetas RFID pasivas. Otros analistas creen que esos precios serían alcanzables dentro de 10 a 15 años.

A pesar de que las ventajas en cuanto al coste de las etiquetas RFID pasivas con respecto a las activas son significativas, otros factores, incluyendo exactitud, funcionamiento en ciertos ambientes como cerca del agua o metal, y fiabilidad, hacen que el uso de etiquetas activas sea muy común hoy en día.

Para comunicarse, las etiquetas responden a peticiones o preguntas generando señales que a su vez no deben interferir con las transmisiones del lector, ya que las señales que llegan de las etiquetas pueden ser muy débiles y han de poder distinguirse. Además de la reflexión o backscatter, puede manipularse el campo magnético del lector por medio de técnicas de modulación de carga"). El backscatter se usa típicamente en el campo lejano") y la modulación de carga en el campo próximo") (a distancias de unas pocas veces la longitud de onda del lector).

Passive tags

Passive tags do not have electrical power. The signal that reaches them from the readers induces a small electrical current sufficient to operate the CMOS integrated circuit of the tag, so that it can generate and transmit a response. Most passive tags use backscatter on the received carrier; That is, the antenna must be designed to obtain the energy necessary to operate at the same time as transmitting the response by backscatter. This response can be any type of information, not just an identifier code. A tag may include non-volatile, possibly writable memory (e.g. EEPROM).

Passive labels usually have distances of practical use between 10 cm (ISO 14443) and reaching up to a few meters (EPC and ISO 18000-6"), depending on the operating frequency and the design and size of the antenna. Due to their conceptual simplicity, they are obtainable through a printing process of the antennas. As they do not require power supply, the device can be very small: they can be included in a sticker or inserted under the skin (low frequency tags).

In 2006, Hitachi developed a passive device called µ-Chip with a size of 0.15 × 0.15 mm without antenna, thinner than a sheet of paper (7.5 µm).[10]​[11]​ SOI (Silicon-on-Insulator) is used to achieve this integration. This chip can transmit a unique 128-bit identifier fixed to it at manufacture, which cannot be modified and confers authenticity to it. It has a maximum reading range of 30 cm. In February 2007 Hitachi presented a device even smaller than 0.05x0.05 mm and thin enough to be embedded in a sheet of paper.[12] These chips have storage capacity and can operate at distances of up to a few hundred meters. Its main drawback is that its antenna must be at least 80 times larger than the chip.

Alien Technology") (Fluidic Self Assembly), SmartCode") (Flexible Area Synchronized Transfer) and Symbol Technologies (PICA) claim to have processes in various stages of development that can further reduce costs through parallel manufacturing processes. These means of production could further reduce costs and drive the economies of scale models of an important sector of silicon manufacturing. This could lead to further expansion of passive tag technology.

There are labels made with polymer-based semiconductors developed by companies around the world. In 2005 PolyIC and Philips introduced simple tags in the 13.56 MHz range that used this technology. If successfully introduced to the market, these labels would be printable like a magazine, with much lower production costs than silicon labels, serving as a fully printed alternative, like current barcodes. However, this requires that they overcome technical and economic aspects, taking into account that silicon is a technology that has been enjoying multimillion-dollar development investments for decades that have resulted in a lower cost than that of conventional printing.

Due to power and cost concerns, the response of a passive RFID tag is necessarily brief, typically just a single identification number (GUID). The lack of its own power source means the device can be quite small: there are commercially available products that can be inserted under the skin. In practice, passive tags have reading distances that vary from about 10 millimeters to about 6 meters, depending on the size of the tag's antenna and the power and frequency at which the reader operates. In 2007, the smallest commercially available device of this type measured 0.05 millimeters × 0.05 millimeters, and thinner than a sheet of paper; These devices are practically invisible.

Active tags

Unlike passive tags, active tags have their own autonomous energy source, which they use to power their integrated circuits and propagate their signal to the reader. These are much more reliable (have fewer errors) than passive ones due to their ability to establish sessions with the reader. Thanks to their energy source, they are capable of transmitting more powerful signals than passive ones, which makes them more efficient in environments that are difficult for radiofrequency such as water (including humans and livestock, mostly made up of water), metal (containers, vehicles). They are also effective at greater distances and can generate clear responses from weak receptions (unlike passive receptions). On the contrary, they tend to be larger and more expensive, and their useful life is generally much shorter.

Many active tags have effective ranges of hundreds of meters and battery life of up to 10 years. Some of them integrate temperature recording sensors and other variables that can be used to monitor food environments or pharmaceutical products. Other sensors associated with RFID include humidity, vibration, light, radiation, temperature, and atmospheric components such as ethylene. In addition to much greater range (500 m), they have greater storage capacities and the ability to store additional information sent by the transceiver.

Currently, the smallest active tags are about the size of a coin. Many active tags have practical ranges of ten meters, and battery life of up to several years.

Characteristics

The main advantage of active RFID tags over passive ones is the high reading range, on the order of tens of meters. As disadvantages, it is worth highlighting the price, which is much higher than the passive ones, and the dependence on battery power. The lifespan of the batteries depends on each label model and also on its activity; it is normally on the order of years. To facilitate battery management, it is common for active RFID tags to send battery level information to the reader, allowing those that are about to run out to be replaced in advance.

These batteries provide the tags with power in standby mode in which the current consumed is very small (generally 3uA) and in operating mode (where 24mA is consumed) these batteries can last from 1 to 10 years, which makes them more robust. The most used are lithium and manganese dioxide such as CR2032 and CR2320. Below are its technical characteristics:

It has the following dimensions according to IEC 60086:.

The discharge performance based on temperature and load resistance is shown in the following graphs:

There are also ultra-thin printed batteries for active packaging design. These batteries are flexible, powerful and less than a millimeter thick, making them ideal for active tags in RFID systems.

Another alternative is paper batteries, which have applications in RFID devices, smart cards and paper LEDs, among others. It is a battery that is made up of thin sheets of chemical compounds embedded in paper, obtaining electrical energy from oxidation-reduction reactions, producing at the terminals a nominal voltage of 1.5 V and a charge of approximately 1.5 mAh.

Semi-passive tags

Semi-passive tags are similar to active tags in that they have their own power supply, although in this case it is mainly used to power the microchip and not to transmit a signal. The energy contained in the radio frequency is reflected towards the reader as in a passive tag. An alternative use for the battery is to store information propagated from the reader to emit a response in the future, typically using backscatter. Batteryless tags must respond by reflecting carrier power from the reader on the fly.

The battery can allow the tag's integrated circuit to be constantly powered and eliminate the need to design an antenna to collect power from an incoming signal. Therefore, antennas can be optimized to use backscattering methods. Semi-passive RFID tags respond faster, so they are stronger in read rate" than passive ones.

This type of tag has a reliability comparable to that of active tags, while being able to maintain the operating range of a passive one. They also tend to last longer than active ones.

What are the differences between barcode and RFID tags?.

One of the essential functions of security seals is to guarantee the correct identification and traceability of the products and merchandise to which they are associated. What are the differences between barcode and RFID tags? The security seal then functions as a vehicle of information thanks to the codes that are integrated into it.

The main differences between identification systems: What are the differences between barcode and RFID tags?

It is interesting to compare more traditional systems such as barcodes against the alternative presented by RFID tags. Let's review the behavior of each one focusing on four main characteristics:.

Information storage capacity.

Versatility and scanning speed.

System cost.

Outstanding advantage.

1. Bar code.

The outstanding advantage of the barcode is its standardization in a multitude of sectors. The simplicity of its use and its correct level of precision make it the most widespread system in the retail or commerce sector and in inventory and logistics management.

However, its information storage capacity is more limited by space: it records up to 20 characters. On the other hand, barcode scanning requires human intervention and direct contact of the reader with the printed information, something that slows down the process.

Regarding cost, barcodes can be printed with simple systems and therefore are not burdensome, but it is true that they are more prone to deterioration in aggressive environments and cannot be modified once they have been printed.

2. RFID tags.

Antenna Types

The type of antenna used in a tag depends on the application for which it is designed and the frequency of operation. Low frequency or LF tags normally use electromagnetic induction. Since the induced voltage is proportional to the frequency, the voltage needed to power an integrated circuit can be produced using a sufficient number of turns. There are compact LF tags (such as those encapsulated in glass, used for human and animal identification) that use an antenna in several levels (three of 100-150 turns each) around a ferrite core "Ferrite (ferromagnetic ceramic)").

At high frequency (HF, 13.56 MHz) a flat spiral with 5 to 7 turns and a form factor similar to that of a credit card is used to achieve distances of tens of centimeters. These antennas are cheaper than LF antennas since they can be produced by means of lithography instead of spiration, although two metal surfaces and one insulator are necessary to make the cross connection from the outer level to the inside of the spiral, where the resonance capacitor and the integrated circuit are located.

Passive ultra-high frequency (UHF) and microwave tags are usually radio-coupled to the reader's antenna and use classic dipole antennas "Dipole (antenna)"). Only one layer of metal is necessary, which reduces cost. Dipole antennas, however, do not fit very well with the characteristics of typical integrated circuits (high input impedance, slightly capacitive). Folded dipoles or short loops can be used as complementary inductive structures to improve power supply. Half-wave dipoles (16 cm at 900 MHz) are too large for most applications (e.g. RFID tags for label use cannot be larger than 10 cm), so antennas must be doubled to meet size needs. Broadband structures can also be used. The gain "Gain (electronic)") of compact antennas is usually lower than that of a dipole (less than 2 dB) and they can be considered isotropic in the plane perpendicular to their axis.

Dipoles undergo coupling with radiation that is polarized on their axes, so the visibility of a tag with a single dipole antenna depends on its orientation. Tags with two octagonal antennas (double dipole tags) are much less dependent on it and the polarization of the reader's antenna, but are typically larger and more expensive than their single counterparts.

Patch antennas can be used to provide service in the vicinity of metal surfaces, although a thickness of 3 to 6 mm is necessary to achieve good bandwidth, in addition to having a ground connection which increases the cost compared to simpler single layer structures.

HF and UHF antennas are usually made of copper or aluminum. Conductive inks have been tested on some antennas, finding problems with adhesion to the integrated circuit and stability of the environment.

Tag association

There are three basic types of labels due to their relationship with the objects they identify: associable, implantable and insertable (attachable, implantable, insertion).[13] In addition to these types of labels, Eastman Kodak has filed two patent applications that deal with monitoring the consumption of medicine in the form of a “digestible” label.[14]​.

Label positioning

Orientation can affect the performance of UHF tags through the air. In general, optimal reader power reception is not necessary to operate passive tags. However, there may be cases in which the distance between both parts is fixed as well as the effective power emitted. In this case, it is necessary to know in which cases you can work optimally with them.

The points called R (resonance spot*), L (live spot*) and D (dead spot*) are defined to specify the location of the tags on a marked object, so that they can still receive the necessary energy based on certain levels of emitted power and distance.[15]​.

Tag environments

The concept of the RFID tag is associated with its ubiquity. This means that readers may require the selection of tags to be explored from among many possible candidates. They may also want to scan tags in their environment to take inventory or, if the tags are associated with sensors and can maintain their values, identify environmental conditions. If an RFID reader tries to work with a set of tags, it must know the devices that are in its area of ​​action and then go through them one by one, or use collision avoidance protocols.

To read the data from the tags, the readers use a singulation algorithm based on tree traversal, resolving any collisions that may occur and sequentially processing the responses. There are blocking tags that can be used to prevent readers from accessing the tags in an area without resorting to suicide commands to disable them. These masquerade as normal labels but have certain specific characteristics; Specifically, they can take any identification code as their own, and can answer any questions they hear, securing the environment by nullifying the usefulness of these questions.

In general, a spurious signal can be emitted if tag activity is detected to block weak tag transmissions. If the labels are expendable or are not needed again, they can be rendered useless by inducing high currents in them that render their circuits useless.

Apart from this, a tag can be promiscuous, if it responds to all requests without exception, or secure, if it requires authentication (this involves the typical aspects of cryptographic and access key management). A tag can be set to activate or deactivate in response to commands from the reader.

Readers in charge of a group of tags in an area can operate in autonomous mode, as opposed to interactive mode. Working this way, they perform periodic identification of all tags in their environment and maintain a presence list with timeouts and control information. If an entry expires, it is removed from the table.

Often a distributed application requires the use of both extreme types of tags. Passive ones cannot perform continuous monitoring tasks, but instead perform tasks on demand when readers request them. They are useful for carrying out regular and well-defined activities with limited storage and security needs. If there are frequent, continuous or unpredictable accesses, or there are real-time or data processing requirements (such as searching internal tables), it is usually convenient to use active tags.

RFID systems are classified depending on the frequency range they use. There are four types of systems: low frequency (LF: 125 or 134.2 kHz); high frequency (HF: 13.56 MHz); ultra-high frequency (UHF: 868 to 956 MHz); and microwave (2.45 gigahertz). UHF systems cannot be used worldwide because there is no single global regulation for their use.

RFID standards address four fundamental areas:

As in other technological areas, standardization in the field of RFID is characterized by the existence of several groups of competing specifications. On the one hand there is ISO, and on the other Auto-ID Center (known since October 2003 as EPCglobal,[16]​ from EPC, Electronic Product Code). Both share the objective of achieving low-cost tags that operate in UHF.

EPC standards for labels are of two kinds:

The classes are not interoperable and are also incompatible with ISO standards. Although EPCglobal") is developing a new generation of EPC standards (called Gen2), with the aim of achieving interoperability with ISO standards, the 8-bit AFI (Application Family Identifier) ​​is still under discussion.

For its part, ISO has developed RFID standards for automatic identification and object management. There are several related standards, such as ISO 10536", ISO 14443 and ISO 15693, but the series of standards strictly related to RFID and the frequencies used in such systems is the 18000 series.

There is no global public corporation that governs the frequencies used for RFID. In principle, each country can set its own rules.

The main corporations that govern the assignment of frequencies for RFID are:

Although the legislation of the radio frequency spectrum is under the sovereignty of each country, there are international organizations that are responsible for establishing uses and recommendations for each band of the electromagnetic spectrum, such as the ITU-R. Most national spectrum legislation bodies are part of the ITU-R regulatory committees and in turn follow the recommendations proposed by this body. You can obtain more information about this body's recommendations regarding RFID systems in its report on the matter.

Low frequency (LF: 125 - 134 kHz and 140 - 148.5 kHz) and high frequency (HF: 13.56 MHz) RFID tags can be used globally without the need for a license. The ultra-high frequency (UHF: 868 - 928 MHz) cannot be used globally, since there is no single global standard. In North America, UHF can be used without a license for frequencies between 908 - 928 MHz, but there are restrictions on transmission power. In Europe ultra-high frequency is under consideration for 865.6 - 867.6 MHz. Its use is license-free only for the range 869.40 - 869.65 MHz, but there are restrictions on transmission power. The US UHF standard (908-928 MHz) is not accepted in France and Italy as it interferes with their military bands. In China and Japan there is no regulation for the use of ultra-high frequency. Each UHF application in these countries requires a license, which must be requested from local authorities, and can be revoked. In Australia and New Zealand the range is 918 - 926 MHz for unlicensed use, but there are restrictions on transmit power.

There are additional regulations related to health and environmental conditions. For example, in Europe, the Waste Electrical and Electronic Equipment regulation does not allow RFID tags to be discarded. This means that RFID tags on cardboard boxes must be removed before disposal. There are also additional regulations regarding health; see electromagnetic field.

Dependiendo de las frecuencias utilizadas en los sistemas RFID, el coste, el alcance y las aplicaciones son diferentes. Los sistemas que emplean frecuencias bajas tienen igualmente costes bajos, pero también baja distancia de uso. Los que emplean frecuencias más altas proporcionan distancias mayores de lectura y velocidades de lectura más rápidas. Así, las de baja frecuencia se utilizan comúnmente para la identificación de animales, seguimiento de barricas de cerveza, o como llave de automóviles con sistema antirrobo"). En ocasiones se insertan en pequeños chips en mascotas, para que puedan ser devueltas a su dueño en caso de pérdida. En los Estados Unidos se utilizan dos frecuencias para RFID: 125 kHz (el estándar original) y 134.5 kHz (el estándar internacional). En Argentina también se utiliza la frecuencia de 125 kHz para las tarjetas plásticas de proximidad de baja frecuencia, aunque también se comercializan modelos de alta frecuencia de 13.56 MHz más versátiles, que permiten operaciones de lectura / escritura y realizar varias aplicaciones al mismo tiempo. Las etiquetas RFID de alta frecuencia se utilizan en bibliotecas y seguimiento de libros, seguimiento de palés, control de acceso en edificios, seguimiento de equipaje en aerolíneas, seguimiento de artículos de ropa y últimamente en pacientes de centros hospitalarios para hacer un seguimiento de su historia clínica. Un uso extendido de las etiquetas de alta frecuencia como identificación de acreditaciones, substituyendo a las anteriores tarjetas de banda magnética. Solo es necesario acercar estas insignias a un lector para autenticar al portador.

Las etiquetas RFID de UHF se utilizan comúnmente de forma comercial en seguimiento de palés y envases, y seguimiento de camiones y remolques en envíos o en sistemas de distribución de uniformidad en hospitales HF(Asturias - España) o incluso en la ropa plana, siempre y cuando la etiqueta sea encapsulada en resina de epoxi, para mayor resistencia al proceso de calandrado y prenda de extracción de agua.

Las etiquetas RFID de microondas se utilizan en el control de acceso en vehículos de gama alta.

Algunas autopistas, como por ejemplo el carril de telepeaje IAVE en las autopistas de CAPUFE en México la FasTrak de California, el sistema I-Pass de Illinois, el telepeaje TAG en las autopistas urbanas en Santiago de Chile, la totalidad de las autopistas pagas argentinas y el E-Pass de Filipinas utilizan etiquetas RFID para recaudación con peaje electrónico"). Las tarjetas son leídas mientras los vehículos pasan; la información se utiliza para cobrar el peaje en una cuenta periódica o descontarla de una cuenta prepago. El sistema ayuda a disminuir el entorpecimiento del tráfico causado por las cabinas de peaje.[18]​.

Sensores como los sísmicos pueden ser leídos empleando transmisores-receptores RFID, simplificando enormemente la recolección de datos remotos.

En enero de 2003, Michelin anunció que había comenzado a probar transmisores-receptores RFID insertados en neumáticos. Después de un período de prueba estimado de 18 meses, el fabricante ofrecerá neumáticos con RFID a los fabricantes de automóviles. Su principal objetivo es el seguimiento de neumáticos en cumplimiento con la United States Transportation, Recall, Enhancement, Accountability and Documentation Act (TREAD).

Las tarjetas con chips RFID integrados se usan ampliamente como dinero electrónico, como por ejemplo la tarjeta Octopus en Hong Kong, tarjeta bip! en Santiago de Chile para el transporte público (Transantiago), la tarjeta SUBE para el transporte de Argentina (metro y buses, especialmente en la Ciudad Autónoma de Buenos Aires), la tarjeta prepago del Sistema Integrado Guatemalteco de Autobuses para uso en el Transurbano y en el Transmetro (Guatemala) "Transmetro (Guatemala)") en Guatemala, Sistema Integrado de Transporte y Transmilenio en Bogotá Colombia, prepago en cinemas Tarjeta Cineco") la tarjeta Cívica en Medellín, y en las tarjetas para el Bus Metropolitano "Metropolitano (Lima)") que opera desde 2010 en Lima, Perú.

Comenzando con el modelo de 2004, está disponible una "llave inteligente" como opción en el Toyota Prius y algunos modelos de Lexus. La llave emplea un circuito de RFID activo que permite que el automóvil reconozca la presencia de la llave a un metro del sensor. El conductor puede abrir las puertas y arrancar el automóvil mientras la llave sigue estando en la cartera o en el bolsillo.

En agosto de 2004, el Departamento de Rehabilitación y Corrección de Ohio (ODRH) aprobó un contrato de 415.000 dólares para ensayar la tecnología de seguimiento con Alanco Technologies"). Los internos tienen unos transmisores del tamaño de un reloj de muñeca que pueden detectar si los presos han estado intentando quitárselas y enviar una alarma a los ordenadores de la prisión. Este proyecto no es el primero que trabaja en el desarrollo de chips de seguimiento en prisiones estadounidenses. Instalaciones en Míchigan, California e Illinois emplean ya esta tecnología.

En abril de 2016 el Club Atlético Tigre de Argentina inició una campaña para que sus hinchas se inyecten un chip con RFID dentro de su cuerpo para controlar su acceso a la cancha. El proyecto de biohacking fue considerado totalmente innovador como extraordinario, generando controversia y desacuerdo por parte de la población, aunque su uso no se piensa como obligatorio sino como alternativo al carnet utilizado usualmente.[19]​.

Libraries

Some libraries use RFID tags to replace barcodes due to their many advantages. These tags can contain information to identify each item within the library and even its usage history. RFID tags can serve as a method of inventory management and also offer self-service to users, so they can return books at any time of the day or night. Book labels can be read while the books are moving on a conveyor belt, reducing staff time. Since RFID tags do not require an optical reader, there is no need to open a book cover or DVD case to scan the item, which is why a stack of books can be read at the same time. Thanks to this, the tags can also serve as a security device with the help of a pair of antennas at the exit of the library. Likewise, with portable readers, library managers can do inventory control on an entire shelf in a matter of seconds.[20]​.

Textile-health sector

Currently, the costs of textile RFID have been significantly reduced, reaching around €0.50 to €0.55. The most resistant are encapsulated in epoxy resin, which are also suitable for automatic garment distribution systems (closets, lockers or hanger systems).[21]​.

These can be inserted into garments very discreetly, inside the hems, heat-sealed or simply sewn.

The ideal is the correct one inserted in the garments, since the position is very important since if it is placed in certain areas, it can cause errors in the reading. The importance of reading quality is fundamental. Having previously selected the hardware, antennas and readers, as well as being located in a non-metallic or properly insulated environment is crucial to achieving 100% reading. Nowadays, thanks to the anti-collision protocol, dozens of garments or objects can be read en masse without the need for direct visibility or without the need to remove the garments from laundry bags, boxes or plastic in just a few seconds.

Thanks to this product in the textile sector, laundry, lingerie and automatic clothing dispensing processes in sectors such as healthcare or fashion, the optimization of human resources and a very important stock reduction of up to 35% in direct inventory and a reduction of up to 50% in the loss, misplacement or theft of garments is achieved. Elements such as reading tunnels are devices that help the user of these systems very precisely, reaching 100% reading.

In Spain, the rise of this technology is clearly growing, although there are very few companies that can offer guarantees of success in the implementation and advice of the devices to use, always HF. In June 2014, the Inditex Group signed an important agreement with Tyco[22]​ to improve inventory processes and reduce unknown loss and theft. With this, the retailer optimizes its investment in inventory and maximizes sales and margins. It is important for a good technological partner in this field to be able to perfectly size the system.[23]​.

In the case of flat clothing, its use is highly conditioned to the selected label, being the most important part to ensure the correct functioning of said garments. Labels encapsulated in epoxy resin have proven to be the only ones resistant to demanding washing processes, where garments are used to extract excess water after the car wash and resistant to calendering, which due to the pressures exerted on the clothes, up to 9 bars, although it is advisable to reduce it to 3 bars (sufficient to secure the fabric), and the high drying temperature up to 180 °C. If its use is required on this clothing, the epoxy encapsulated label is the most recommended, since other flat cotton or plastic label solutions end up breaking or melting, with the consequent detriment to the project. There are several companies that are experts in this type of label, although TagsysRfid is the one that can provide the most experience, due to the large number of references in the textile-health sector. The Fujitsu company has recently developed WT-A522 labels with a non-metallic antenna with the capacity to be used in MRI environments, and to massively read more than 500 garments in just a few seconds, allowing total traceability of all hospital flat clothing.

Logistics[25][26]​

Currently, the most important application of RFID is logistics. The use of this technology would allow any product to be located within the supply chain. In relation to traceability, labels could have great application since they can be recorded, which would allow us to know how long the product was stored, in which locations, etc. In this way, important optimizations can be achieved in the management of products in supply chains based on the same product, and becoming practically independent of the information system.

Due to the size of these two organizations, their RFID mandates have impacted thousands of companies around the world. The deadline has been extended several times because many manufacturers face great difficulties in implementing RFID systems. In practice, successful reading numbers are currently at 80%, due to radio wave attenuation caused by products and packaging. Soon it is expected that even the smallest companies will be able to put RFID tags on their transport.

Since January 2005, Walmart required its top 100 suppliers to apply RFID tags to all of their shipments. In order to meet the requirement, manufacturers use RFID encoders/printers to label boxes and pallets that require EPC labels for Walmart. These smart labels are produced by integrating the RFID into the label material, and printing the barcode and other visible information on the surface of the label.

human implants

Implantable RFID chips, originally designed for animal tagging, are being used and are being considered for humans as well. Applied Digital Solutions" proposes its unique under-the-skin format chip as a solution to identity theft, secure building access, computer access, medical record storage, anti-kidnapping initiatives and a variety of applications. Combined with sensors to monitor various body functions, the Digital Angel device could provide patient monitoring. The Baja Beach Club in Barcelona (Spain) uses an implantable Verichip to identify its VIP customers, who use it to pay for drinks. The Mexico City police department has implanted the Verichip in about 170 of its police officers, to allow access to police databases and to be able to track them if they are kidnapped.

Marketing/Events Sector

Nowadays RFID has been used to control visitors at events and recreational parks. This has made it possible to connect social networks with RFID. Events like CES in Las Vegas, NV and others have brought a lot of attention to potential new industries. RFID is already used as an electronic wallet method to make payments within amusement parks [1]. This shows a great advance of the RFiD system trying to take the use of the magnetic stripe.

Las etiquetas RFID se ven como una alternativa que reemplazará a los códigos de barras UPC o EAN, puesto que tienen un número de ventajas importantes sobre la arcaica tecnología de código de barras. Quizás no logren sustituir en su totalidad a los códigos de barras, debidos en parte a su costo relativamente más alto. Para algunos artículos con un coste más bajo la capacidad de cada etiqueta de ser única se puede considerar exagerado, aunque tendría algunas ventajas tales como una mayor facilidad para llevar a cabo inventarios.

También se debe reconocer que el almacenamiento de los datos asociados al seguimiento de las mercancías a nivel de artículo ocuparía muchos terabytes. Es mucho más probable que las mercancías sean seguidas a nivel de palés usando etiquetas RFID, y a nivel de artículo con producto único, en lugar de códigos de barras únicos por artículo.

Los códigos RFID son tan largos que cada etiqueta RFID puede tener un código único, mientras que los códigos UPC actuales se limitan a un solo código para todos los casos de un producto particular. La unicidad de las etiquetas RFID significa que un producto puede ser seguido individualmente mientras se mueve de lugar en lugar, terminando finalmente en manos del consumidor. Esto puede ayudar a las compañías a combatir el hurto y otras formas de pérdida del producto. También se ha propuesto utilizar RFID para comprobación de almacén desde el punto de venta, y sustituir así al encargado de la caja por un sistema automático que no necesite ninguna captación de códigos de barras. Sin embargo no es probable que esto sea posible sin una reducción significativa en el coste de las etiquetas actuales. Se está llevando a cabo una investigación sobre la tinta que se puede utilizar como etiqueta RFID, que reduciría costes de forma significativa. Sin embargo, faltan todavía algunos años para que esto dé sus frutos.

Gen 2

An organization called EPCglobal is working on an international standard for the use of RFID and EPC in identifying any item in the supply chain for companies in any type of industry, anywhere in the world. The organization's top council includes representatives from EAN International"), Uniform Code Council"), The Gillette Company"), Procter & Gamble, Wal-Mart, Hewlett-Packard, Johnson & Johnson, SATO, and Auto-ID Labs"). Some RFID systems use alternative standards based on the ISO 18000-6 classification.

The EPCglobal gen 2 standard was approved in December 2004, and is likely to form the backbone of RFID tag standards going forward. This was approved after a challenge from Intermec over the possibility that the standard could infringe several of its RFID-related patents. It was decided that the standard itself did not infringe its patents, but that royalties may have to be paid to Intermec if the tag were read in a particular way. EPC Gen2 is the abbreviation of EPCglobal UHF Generation 2.

In June 2006, the ISO adopted the standard under the name ISO/IEC 18000-6C.

Patient identification

In July 2004, the U.S. Food and Drug Administration made public a decision to begin a study process that will determine whether hospitals can use RFID systems to identify patients Hospital La Fe or to allow access by relevant hospital personnel to medical records.") The use of RFID to prevent mixing of sperm and eggs in IVF clinics is also being considered. [2]. Additionally, the FDA recently approved the first U.S. RFID chips that can be implanted in humans. The 134.2 kHz RFID chips, from VeriChip Corp., a subsidiary of Applied Digital Solutions Inc., can incorporate personal medical information and could save lives and limit injuries caused by medical treatment errors, according to the company. disclosed during a conference call with investors. Its application in the home has also been proposed, to allow, for example, a refrigerator to know the expiration dates of the food it contains, but there has been little progress beyond simple prototypes.

Another use in the health sector is the location of clinical records, within a mass environment or decentralized warehouses, that is, in warehouses outside the hospital. Inventory management and location can be greatly improved with incredible results just by putting an RFID chip in them. Furthermore, with mass reading devices, 100% reading of clinical records can be guaranteed and complete traceability can be achieved without problems and in a very simple way.

Traffic and positioning

Another proposed application is the use of RFID for "smart traffic signs" on the road. It is based on the use of RFID transponders buried under the pavement (radio beacons) that are read by an onboard unit (OBU) that filters the various traffic signs and translates them into voice messages or gives a virtual projection using a HUD (Heads-Up Display). Its main advantage compared to satellite-based systems is that Radio beacons do not need digital mapping since they provide the traffic signal symbol and position information by themselves. RFID radio beacons are also useful to complement satellite positioning systems in places such as tunnels or interiors, or in guiding blind people.

El uso de la tecnología RFID ha causado una considerable polémica e incluso boicots de productos. Las cuatro razones principales por las que RFID resulta preocupante en lo que a privacidad se refiere son:.

La mayoría de las preocupaciones giran alrededor del hecho de que las etiquetas RFID puestas en los productos siguen siendo funcionales incluso después de que se hayan comprado los productos y se hayan llevado a casa, y esto puede utilizarse para vigilancia y otros propósitos cuestionables sin relación alguna con sus funciones de inventario en la cadena de suministro. Aunque la intención es emplear etiquetas RFID de corta distancia, estas pueden ser interrogadas a mayores distancias por cualquier persona con una antena de alta ganancia "Ganancia (electrónica)"), permitiendo de forma potencial que el contenido de una casa pueda ser explorado desde cierta distancia. Incluso un escaneado de rango corto es preocupante si todos los artículos detectados aparecen en una base de datos cada vez que una persona pasa un lector, o si se hace de forma malintencionada (por ejemplo, un robo empleando un escáner de mano portátil para obtener una evaluación instantánea de la cantidad de víctimas potenciales). Con números de serie RFID permanentes, un artículo proporciona información inesperada sobre una persona incluso después de su eliminación; por ejemplo, los artículos que se revenden, o se regalan, pueden permitir trazar la red social de una persona.

Otro problema referente a la privacidad es debido al soporte para un protocolo "Protocolo (informática)") de singulation (anticolisión). Esta es la razón por la cual un lector puede enumerar todas las etiquetas que responden a él sin que ellas interfieran entre sí. La estructura de la versión más común de este protocolo es tal que todos los bits del número de serie de la etiqueta salvo el último se pueden deducir por espionaje pasivo a distancia tan solo en la parte del protocolo que afecta al lector. Por esta razón, si las etiquetas RFID están cerca de algún lector, la distancia en la cual la señal de una etiqueta puede ser escuchada es irrelevante. Lo que importa es la distancia a la que un lector de mucho más alcance puede recibir la señal. Independientemente de que esto dependa de la distancia a la que se encuentre el lector y de qué tipo sea, en un caso extremo algunos lectores tienen una salida de energía máxima (4 W) que se podría recibir a diez kilómetros de distancia.

Passports

Several countries have proposed the implementation of RFID devices in new passports, to increase the efficiency of biometric data reading machines. Security expert Bruce Schneier said of these proposals: "It's a clear threat to both personal security and privacy. It's simply a bad idea." Passports with integrated RFID only identify their bearer, and in the proposal being considered, would also include other personal data. This could make some of the abuses of RFID technology just discussed much simpler, and the amount of data could be expanded to include, for example, abuses based on reading a person's nationality. For example, an assault near an airport could target victims who have arrived from wealthy countries, or a terrorist could design a bomb that would work when near people from a particular country.

The United States Department of State initially rejected these hypotheses because they thought that the chips could only be read from a distance of 10 cm, without taking into account more than 2,400 critical comments from security professionals, and a clear demonstration that with special equipment passports can be read from 10 m. [28]​.

Pakistan Passport Authority has started issuing passports with RFID tags.

Driving license

The U.S. state of Virginia has considered putting RFID tags on driver's licenses to make checking faster for police and other officials. The Virginia General Assembly also hopes that by including the tags, it will cost much more to obtain fake IDs. The proposal was first introduced in the Driver's License Modernization Act of 2002, which was not enacted, but in 2004 the concept was still being considered.

The idea was promoted by the fact that several of the 9/11 hijackers had fraudulent Virginia driver's licenses. However, the American Civil Liberties Union said that in addition to being a risk to privacy and freedom, the RFID proposal would not have hindered terrorists, since the false documentation they carried was valid, since they were official documents obtained with another false identification. The weakness of the system is that it does not fail when validating documents at the time, but rather it fails to verify identity before issuing them.

Under the proposal, no information would be stored on the tag except for the number corresponding to the bearer's information in a database, only accessible by authorized personnel. Furthermore, to deter identity fraud") it would only be necessary to wrap a driver's license in aluminum foil. [5].

Faraday shielding as a countermeasure to RFID

A Faraday cage can be used to prevent radio frequency signals from escaping or entering an area, acting as an RF shield.

If an RFID device were surrounded with Faraday shielding, it would have greatly attenuated incoming and outgoing signals, to the point that they would not be usable. A very simple Faraday shield, suitable for most purposes, would be an aluminum foil wrapper. A more effective one would be a copper rectangle around the object. An implanted RFID would be more difficult to neutralize with such shielding, but even a simple aluminum foil covering would attenuate the electric field component of the signals.

Permanently neutralizing the RFID may require a strong alternating electrical current adjacent to the RFID, which overloads the tag and destroys its electronics. In some cases, depending on the composition of the RFID, a strong magnet may serve to mechanically destroy the coil or chip connection by mechanical force exerted on the coil. With the development of RFID technology, other methods may be necessary.

The 125 kHz, 134 kHz (low frequency), and in several cases 13.56 MHz (high frequency) tags are linked by a magnetic field rather than an electric field, called inductive coupling. Since the Faraday cage shields only the electrical component of the electromagnetic field, aluminum foil shielding is ineffective. Any magnetic shielding, such as a thin sheet of iron or steel, encapsulating the tag's antenna coil, will be effective.