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RFID Systems for Enhanced Shopping Experiences

by Walter Reade and Jeff Lindsay

The following article was published Dec. 23, 2003 on as Article 21115D, available at

Related articles at on radiofrequency identification (RFID) technology:

Table of Contents

RFID Systems for Enhanced Shopping Experiences

Walter Reade and Jeff Lindsay
Nov. 10, 2003


RFID (radiofrequency identification) technology offers the ability to provide many new services and conveniences in the retail environment. As has been demonstrated in the Metro Group Future Store in Rheinberg, Germany (Metro AG, with headquarters in Düsseldorf, Germany) described in a series of movies and other files at, shoppers can be guided electronically to find desired products that are tagged with RFID chips and whose locations are tracked by RFID readers in the store (e.g., smart shelves or other reader systems). Smart shopping carts with electronic displays, in communication with a retail computer system, can display a map associated with a shopping list downloaded by a shopper to identify a route to obtain the desired items. The smart cart, also equipped with RFID tags, can also verify the purchase of the items as they are placed in the cart and, if desired, communicate with a billing system to automatically bill the shopper for the purchases.

In addition to the systems that have been demonstrated and widely discussed in the literature, several additional improvements can be expected as RFID technology begins to become more ubiquitous. In general, these concepts can be described in the context of guided shopping experiences for consumers, enhanced by the information flow enabled with RFID technology and other electronic systems.

List Generation and Handling

The guided shopping experience of the future may begin with a list of shopping needs and desires. The list may be created in part by automatic processes, such as an RFID-enabled pantry or refrigerator that detects the need to restock a commonly purchased item or other item that the user has specified should be maintained in some specified quantity. Such systems may create a proposed shopping list that can be edited by the user using a PDA (personal digital assistant), cell phone, a computer, a Web page, and the like. The electronic list may be transmitted in advance to a designated retail store or electronic database accessible by the retail store, or may be stored in memory on a smart card, a writable RFID chip, PDA, or other computer-readable memory. The list in electronic or other form may be carried by the shopper to the retail store, or transmitted electronically by e-mail, over the Internet, and so forth. In one variation, the list is stored in a central database such as on a secure Web site that can be accessed by the user via a plurality of computer systems at various retail stores. Thus, the user can select a store to shop at and then enter a code or provide identification information, including RFID tags, to call up the shopping list information.

Once the list is loaded into a computer system at the retail environment, the list can be interpreted to assist the shopping experience of shopper. The retail computer system can electronically display a check list based upon the shopping list using a display device on a smart cart, a PDA device, cell phone, or other electronic device. Alternatively, display of the list may be executed by a computer system not belonging to the retail store, such as on a cell phone, a PDA owned by the shopper or a third party, and the like, wherein a computer program can communicate with a computer system of the retail store.

The displayed list can be used to guide the shopper and track purchases. To track purchases, a computer program that is associated with the system that control the display of the list or other information to guide the shopper may allow the user to manually check off items on the list when the listed items have been purchased, or RFID readers can detect the placement of the targeted items in a shopping cart to automatically indicate that the items have been selected. The total cost of the items selected at any point can readily be displayed.

To further guide the shopper, a map can be displayed on a display device showing the aisles of the retail environment, with indicia to show where targeted items are. A routine can generate and display to the shopper an optimized route that requires the smallest distance traveled, or optimized routes that fulfill user-specified constraints (e.g., minimize distance traveled with the proviso that frozen goods are picked up last, or in the last 20% of the distance traveled, to prevent premature thawing). In one version, the retailer may have the option to adjust the map to guide the consumer to targeted regions featuring promotions, special displays, free samples, etc. (preferably with the knowledge of the consumer). Alternatively, the map display may have options to allow the user to select alternative routes to achieve objectives such as maximizing exposure to promotions of selected types, or to ensure the all free sample booths in the store are included in the route, or to include access to restrooms or other desired features of a retail environment.

Improved Smart Shelves

An important element of the guided shopping experience is the ability of the retailer to recognize what is on the shelves at any moment in order to keep the shelves properly stocked and to guide the consumer to the proper location of the desired products. Smart shelves can be a valuable tool in achieving this purpose. Some concepts are discussed in PCT publication WO 00/65532, "Storage System," published Nov. 2, 2000, by Kevin Ashton, former Director of the Auto-ID Center. Smart shelf units under the name "SmartShelf" have been manufactured by SAMSys Technologies, Inc. (Ontario, Canada). However, there have been several limitations to such systems. Smart shelves in early demonstration trials in Europe and the United States have been both expensive and cumbersome, with multiple stand-alone readers installed at multiple locations along a single shelf to track items at various stations. The use of coaxial cable for these readers has resulted in cluttered equipment around the shelves. Furthermore, these shelf units may not be suitable for end-aisle display units or for use in the storage area, where items may be stored in boxes or on pallets in a disorderly fashion.

As an improvement, advanced smart shelves have been developed in which a single antenna or single array of interconnected antennas with a single reader can be used to determine the location along a shelf. One such technology is that discussed by D.G. Bauer et al., "Intelligent Station Using Multiple RF Antennae and Inventory Control System and Method Incorporating the Same," US Patent Publication 200030174099-A1, published Sept. 18, 2003, filed as US patent application Serial No. 10/338892, assigned to MeadWestvaco Corporation.

Another technology for smart shelves that is said to eliminate the need for coaxial cable and provide good resolution on a shelf at low cost is the recirculating phase array antenna system of AWID (Applied Wireless Identification Group, Hollister, California) coupled with their fast look-ahead decay sensing system. Such antenna systems can be provided in roll-to-roll form for easy retrofitting of existing shelves, as discussed by AWID President, Jeffrey Jacobsen, "Low Cost, Digitally Amplified Shelf Antennas," Proceedings of the Smart Label Europe 2003 Conference (available on CD-ROM), Cambridge, England, Sept. 29-30, 2003, sponsored by IDTechEx. A film provided with the antennas and conductive leads can be provided for rapid placement on the surface of a shelf where it may be hidden under paper or other materials. Associated with the antenna system are additional electronics for signal reading and processing.

In spite of these advances, there are some situations in which smart shelves are impractical, impossible, or perhaps too expensive for effective object tracking using RFID technology. Alternatives are needed for location the position of targeted objects associated with RFID tags.

Prior Shopping Enhancements Adaptable for RFID-Enabled Shopping Systems

Many other previously proposed systems to improve the retail shopping experience can be adapted to an RFID-enabled shopping system. For example, a system that allows shoppers to be identified in order to receive customized promotional offers was proposed by Peter Abell in "In Store Consumer Targeted Messaging System," PCT Publication WO 98/38589, published Sept. 3, 1998. Such targeted marketing can easily be applied in RFID-enabled environments once the shopper is identified. Shopper identification can be done by reading an RFID tag associated with user ID, by a card swipe system, by biometric techniques, and so forth.

Systems also exist to allow shoppers to verify their bill prior to check out, and this can further be adapted for RFID-enabled systems. For example, US Patent No. 6,308,888, "Arrangement for and Method of Expediting Commercial Product Transactions at a Point-of-Sale Site," issued Oct. 30, 2001 to Swartz teaches systems that can be adapted for this purpose, though the bar-code concepts therein would be replaced with RFID technology. However, instead of the scanning stations of US Patent No. 6,308,888, scanning and summary information can be provided automatically by a smart shopping cart.

Sensors and product life indicators can also be adapted to provide useful information to assist shoppers. For example, products may be associated with time and temperature indicators that provide integrated information about exposure to unsuitable temperatures in order to help predict when a product may no longer be fresh. This information may be converted via wireless or other electronic means. A shopper may enter requirements about desired degrees of freshness, coupled with an option to pay premium for the freshest foods. For example, the shopper's list may indicate that milk must have a shelf life of at least three weeks past the purchase date. Sensors or a supply chain database associated with the milk may indicate that some available milk jugs only have a two week life time, but that a batch of milk with a three-week expected shelf life is available. The user may be required to pay a small fee for the privilege of automatic assistance in selecting the freshest milk, or the freshest milk may be provided at a slightly higher price. One useful tool for tracking freshness of products is the Infratab (Oxnard, California) FreshAlertTM system of electronic tags and sensors, including RFID tags adapted for integration into the supply chain.

Combinations of RFID-based methods with machine vision systems are also contemplated. For example, an RFID-enabled retail environment can further be enhanced with machine vision systems that can identify objects that may not suitable for RFID tag attachment, such as fresh fruit, quantities of peanuts or other nuts, and the like. One useful vision-based system is IBM's "Veggie Vision" system that can identify produce and assist in automatic billing for the quantity selected. For further details, see


Basic aspects of a guided-tour system are shown in Figures 1 and 2. Figure 1 illustrates a high-level block diagram of an RFID system 100 for optimizing the pedestrian route taken by a consumer within a retail establishment. The RFID system 100 includes a manufacturing database 110, an electronic processing center 112, and a retailer database 114 all interconnected via a standard wired or wireless communications link 116 used commonly for computer networking. The manufacturing database 110 resides on a central computer (not shown) that may be associated with a manufacturing location. Various types of product information stored and maintained in the manufacturing database 110 may include product specifications, internal movement within the manufacturing environment, shipment history, sales transactions, and promotional offerings. The electronic processing center 112 is a central computer associated with a distribution center that manages, for example, manufacturing financial accounts, retailer financial accounts, manufacturing promotional offerings, and product specifications. The retailer database 114 resides on a central computer (not shown) associated with a retail location. Various types of product information stored and maintained in the retailer database 114 include product specifications, internal movement within the retail environment, shipment history, sales transactions, and manufacturer/retailer promotional offerings.

Access to the RFID system 100 is accomplished via a plurality of user interfaces 118, which are electrically connected to communications link 116. Examples of a user interface 118 include a host computer, a personal computer (PC), smart shopping cart, multifunctional cell phone, or a PDA. The various user interfaces 118 are located wherever access is required within the RFID system 100, such as in a manufacturing facility, a distribution facility, or a retail facility.

Additionally, the RFID system 100 includes a plurality of retail products 120 each having an associated RFID tag 122. Retail products 120 are representative of any of a wide variety of consumer products, such as food items, clothing, household items, automotive parts, medical goods, and so forth, located anywhere along the supply chain, such as in the manufacturing facility, in the distribution facility, in the retail facility, or in the possession of a consumer. Each individual retail product 120 is identified via an associated RFID tag 122.

Each RFID tag 122 is a well-known electronic product code (EPC) device that provides a unique factory-programmed identification code. Each RFID tag 122 is, for example, a low frequency, battery-free transponder device that is read via radio waves. An example of RFID tag 122 is an RFID tag manufactured by Texas Instruments Inc. (Dallas, TX). Typically, up to 96 bits of information are stored upon each RFID tag 122. These 96 bits provide product information, such as product name, product manufacturer, a 40-bit serial number, and so forth. The RFID tag 122 may be a read-only device, a read/write device that can be programmed, or a device with a challenge/response authentication feature for the highest grade of security.

The factory-programmed identification code (e.g., EPC) contained within each RFID tag 122 may be extracted via a one of several RFID readers 124 located within RFID system 100. Each RFID reader 124 is an electronic device, including an RF transmitter and receiver and an antenna to communicate with RFID transponders, such as RFID tags 122. Each RFID reader 124 may be a stationary or portable (e.g., handheld) device that scans RFID tags 122 via radio waves and passes the information in digital form to RFID system 100 via a reader interface 126. An example of an RFID reader 124 is an RFID reader manufactured by Antenova Ltd. (Cambridge, England) or a Bancolini B30 handheld RFID scanner manufactured by Bancolini (Bologna, Italy). The reader interface 126 may be a digital interface, for example, a standard PC or PDA device that serves as a parallel or serial connection to communications link 116 of the RFID system 100 via a wired or wireless means. The reader interface 126 is representative of one or several interfaces that may be located within the RFID system 100.

For a given retail supply chain, the operation of the RFID system 100 is described as follows. As retail products 120 are manufactured and tagged with an associated RFID tag 122, the factory-programmed identification codes contained in the RFID tag 122 are logged within the manufacturing database 110 of the RFID system 100 on a per retail product 120 basis (other bases may be used, if desired). Subsequently, as retail products 120 are distributed (i.e., transported) from the manufacturer to a given distribution center, the factory-programmed identification codes of each retail product 120 are logged within the electronic processing center 112, which is associated with a distribution center. As retail products 120 are distributed from the distribution center to a given retailer, the factory programmed identification codes of each retail product 120 are logged within the retailer database 114, which is associated with a retail location. Throughout the distribution process, information such as product specifications, shipment history, sales transactions, and promotional offerings follow each retail product 120. Those skilled in the art will recognize that the electronic processing center 112 may be associated with several manufacturing databases 110 as well as several retailer databases 114; however, for simplicity only one manufacturing database 110 and one retailer database 114 are shown in Figure 1.

All data transfer within the RFID system 100 is accomplished via communications link 116. Once retail products 120 arrive at a given retail location, retail products 120 are placed upon shelf units 128 according to the capacity of each shelf unit 128, with any remaining retail products 120 kept in a local stock room (not shown). The location of each retail product 120 within a given retail location is tracked by reading its associated RFID tag 122 and correlating the information therein with a known location within the retail site. Smart shelves (not shown) may be used in this process, or any other system of scanning objects on shelves, including manual scans, scans from long-distance scanners, etc. In one variation, overhead-mounted RFID readers 124 work in combination with a motion control system (not shown) to frequently scan the full inventory of a retail facility and thereby keep the retailer database 114 current at all times. Directional beams with electronic or servo-motor systems to control beam direction may also be used to scan RFID tags at various locations.

The previously mentioned known locations within the retail site include a specific store aisle and shelf unit 128, a specific location in the stock room(s), or product in transition from local stock to a given shelf unit 128 on apparatus such as standard stockroom carts or automatic guided vehicles (AGVs), and so forth. This is accomplished via one or more RFID readers 124 located within the retail location or on these apparatuses. More specifically, via their radio frequency receiver units, one or more RFID readers 124 collect the factory-programmed identification codes from RFID tags 122 and then transmit them via one or more reader interfaces 126 to the retailer database 114, where the management software of RFID system 100 updates the retailer database 114 accordingly.

As an example, one or more RFID readers 124 are mounted within a retail shelf, and the location of both the retail shelf and RFID readers 124 is known to retailer database 114. Thus, any information transmitted to retailer database 114 can be processed and used to log the location of any retail product 120 within the retail environment. An example of such a shelf is a "SmartShelf" manufactured by SAMSys Technologies, Inc. (Ontario, Canada). Using either of the examples above, as retail products 120 are removed from retail shelves or from the stock room, retailer database 114 is updated as to their movement. This information may be accessed by supply chain or retailer personnel at any time via one of the user interfaces 118, thereby allowing retail products 120 to be replenished at the appropriate time and place based upon inventory status.

The RFID system 100 further includes an Internet link 128 and one or more shopper interfaces 130. The Internet link 128 provides a convenient medium for a given retailer, for example, to post store or product information to potential consumers, and likewise provides a convenient medium for consumers to access this retailer information for use in making purchase decisions. Shopper interfaces 130 provide a wired or wireless link to RFID system 100 for consumers once they enter, for example, the physical retail facility. Examples of shopper interfaces 130 include a store kiosk computer, a consumer's PDA device, a voice recognition device, or a shopping cart having built-in electronic interfaces, such as PDA devices or other electronic display devices.

In operation, for a given retailer or retailer type, such as a grocery store or department store, a consumer may enter specific purchasing preferences or a specific shopping list via, for example, a home PC with access to RFID system 100 via Internet link 128 or alternatively within the retail facility itself using shopper interface 130. Software algorithms within RFID system 100 use a predetermined map of the facility to correlate the specific retail products 120 entered by the consumer to a specific location within the retail facility to generate an optimized shopping guide. In this way, RFID system 100 determines an optimum path for the consumer to travel within the retail establishment to find, select and purchase specific retail products 120. RFID system 100 optimizes the consumer's time and walking distance by communicating to the consumer the most efficient route within the retail facility for retrieving the specific retail products 120. This communication maybe accomplished via a printed map, via the display of the in-store shopper interface 130, or via an audio device for emitting an audible voice or tone when the consumer is in close proximity to a specific retail product 120 on his/her list. Hypersonics can also be used to provide a directed audio signal. This is possible due to RFID system 100 keeping a current location-specific inventory record within retailer database 114 for the specific retail facility. In addition, the consumer is informed of products that may be of interest to them, for example acceptable alternatives to out-of-stock items, discounted items, and various purchasing incentives and promotions. Since the RFID system 100 can track the location of the consumer via, for example, the use of a "Smart" cart, these alternative items may be displayed in real time as the consumer encounters these items along his/her shopping path. Tracking of the consumer in the store can be done in a variety of way, including the use of RFID tags associated with the consumer (e.g., in an identity card, a loyalty card, in the shopping cart used by the consumer, or in another object carried by the consumer), video surveillance, etc.

Over time, the software algorithms associated with the RFID system 100 are able to generate a list of favorite retail products 120 for each specific consumer based the consumer's preferences and purchasing history that is being continuously logged in retailer database 114. As a result, a shopping list with its associated optimized purchasing route may be automatically generated for each consumer and available either online or at the store, thereby further optimizing the consumer's time.

Figure 2 shows a flow diagram of a method 200 of providing an optimized purchasing route within a retail establishment based on consumer preferences and potential purchases, including the display of this route, and other pertinent information to the consumer. The method 200 includes the following steps:

Step 210: Entering consumer preferences In this step, for a given retailer or retailer type, such as a grocery store, department store, book store, or automotive parts store, a consumer may enter specific purchasing preferences or a specific shopping list via, for example, a cell phone or a home PC with access to RFID system 100 via Internet link 128 or alternatively within the retail facility itself using a shopper interface 130, such as a PDA, a personal computer with Internet access, a computerized kiosk equipped with a touch-screen, and the like. The purchasing preferences include preferred brands, price range, commonly purchased products and other familiar shopping criterion. The consumer may establish a series of rules, including fuzzy-logic based rules to simulate the normal decision making process of the consumer in light of competing objectives. The method 200 proceeds to step 220.

Step 220: Generating favorites list In this step, software algorithms associated with the RFID system 100 generate a list of favorite retail products 120 for the consumer. This list is derived from consumer purchasing history recorded in retailer database 114 and from the consumer preferences list of step 210. An alternative embodiment may require the consumer to enter a favorites list using shopper interface 130. Other embodiments will use a combination of consumer-defined favorites and favorites generated by RFID system 100. The method 200 proceeds to step 230.

Step 230: Creating consumer-shopping list In this step, the consumer enters a list of desired retail products 120 to be purchased via a shopper interface 130. The list of desired retail products 120 can be either generic or brand-specific, or may include rules to guide in the automated selection of products based on consumer needs and preferences. The method 200 proceeds to step 240.

Step 240: Optimizing shopping route In this step, software algorithms associated with the RFID system 100 determine an optimum path for the consumer to travel within the retail establishment to find, select and purchase the retail products 120. The algorithm creates the optimal shopping route based on consumer preferences entered in step 210, knowledge of the store layout, and the consumer-shopping list created in step 230, among other varied criteria. The method 200 proceeds to step 250.

Step 250: Guiding the consumer through the store In this step, the RFID system 100 displays to the consumer an optimal purchasing route through the retail establishment, as determined in step 240, via a map displayed on the shopper interface 130, or a printed map, or through numerous additional means, such as an audible indication or other visual indications. The method 200 proceeds to step 260.

Step 260: Providing the consumer with additional information In this optional step, the consumer is informed of other products that may be of interest, for example acceptable alternatives to out-of-stock items, discounted items, and various purchasing incentives and promotions. The alternatives may be in response to rules, including fuzzy logic rules, previously entered by the consumer. Communication is accomplished via a shopper interface 130. The method 200 proceeds to step 265.

Step 265: Purchasing retail products In this step, having completed the shopping experience using the optimized shopping route, the consumer purchases retail products 120. Purchase of retail products 120 is by any conventional transaction method. The method 200 ends.

Figure 1. Components of an RFID system.
Figure 1. Components of an RFID-enabled system for optimizing a retail shopping experience.

Figure 2. Steps in the RFID method.
Figure 2. Steps in an RFID-enabled method for optimizing a retail shopping experience.


The rich flow of information enabled by ubiquitous RFID tags associated with products can transform shopping experiences into efficient and economical experiences with many conveniences not currently enjoyed by most shoppers. While concerns over privacy may still need to be addressed, and some technical problems remain for effective and low-cost implementation of RFID on some products, we expect to see the nature of retail shopping gradually make many advances through intelligent information systems such as those based on RFID.

Appendix: RFID Basics

Basic principles of RFID technology are given by Raghu Das, "RFID Explained: An Introduction to RFID and Tagging Technologies," white paper from IDTechEx Ltd. available at, dated 2003, as viewed Aug. 19, 2003. The author defines RFID as follows:
Radio Frequency Identification (RFID) is the use of radio frequencies to read information on a small device known as a tag. . . Radio frequency Identification (RFID) is a term used for any device that can be sensed at a distance by radio frequencies with few problems of obstruction or misorientation. The origins of the term lie in the invention of tags that reflect or retransmit a radio-frequency signal. In its current usage, those working below 300Hz and those working above 300MHz, such as microwave (GHz) tags, are included. For example, one type of chipless tag works at only a few hertz and Inkode chipless taggants operate at around 20-25 GHz. Higher frequencies such as visible and infrared devices are excluded as these systems have very different properties and are frequently sensitive to obscuration, heat, light and orientation.

The term "tag" is used to describe any small device--shapes vary from pendants to beads, nails, labels or microwires and fibres that can be incorporated into paper and even special printed inks on, for example, paper.

Examples of potential applications for smart chips attached to products and wireless communication systems are described by C.R. Schoenberger in "The Internet of Things," Forbes, March 18, 2002, pp. 155-160. Further information on these technologies is provided at and, and more technical information has been provided by MIT's Auto-ID Labs (formerly the Auto-ID Center), Cambridge, Mass. Useful information from the Auto-ID Labs can be accessed from and other information can be obtained at See also "Toward the 5 Tag" by Sanjay Sarma, Auto-ID Center, Nov. 2001, available at, and "Integrating the Electronic Product Code (EPC) and the Global Trade Number (GTIN)," by David L. Brock, Auto-ID Center , Nov. 2001, available at

An overview of the history of RFID is given by Jeremy Landt in "Shrouds of Time: The History of RFID," AIM (Association for Automatic Identification and Data Capture Technologies), Pittsburgh, Pennsylvania, Oct. 1, 2001, available at

RFID chips can be used to track products grouped in various hierarchies: (1) individual items or single packages containing multiple items for consumer purchase; (2) cartons or cases of multiple items; (3) pallets of multiple cartons or cases; and (4) loads (e.g., truckloads, shiploads, or railcar loads) of multiple pallets. The products at each of these levels may be assigned an RFID label that is associated with information pertaining to at least one adjacent hierarchical level. For example, an RFID label on a pallet may be associated in a database with the RFID labels for each carton on the pallet, or may be associated with data pertaining to the RFID label from the truckload.

RFID tags of any known type may be used, including:

While RFID tags typically include a semiconductor chip associated with an electronic code, chipless RFID technologies are also known.

Examples of low-cost technologies for producing chip-based RFID systems listed by Raghu Das (2003) include:

For chipless RFID, Das lists the following as available low-cost RFID technologies:

Transistor-based chipless circuits can include laminar transistor circuits, including polymer film circuits such as those of Plastic Logic, Inc. or Philips Research Laboratories, thin film silicon, bioelectronics, etc. Magnetic wire and fiber systems for chipless RFID can include the products of MXT (Canada), HID (US), British Technology Group (UK), Fuji Electric (Japan), REMOSO Development (Netherlands), and Advanced Coding Systems (Israel). Laminar transistorless circuits can include diode circuits, printed electronics, EM tags of ACS, surface acoustic wave technology such as that of RF SAW, Inc., and LC arrays (swept RF) such as the devices of CWOSRFID (US) and Lintec (Japan), Miyake (Japan), Checkpoint (US), MIT Medialab (US), the rewritable chipless tag of Navitas (Japan). Thin magnetic films for chipless RFID can include conventional magnetics for non-contact reading, or the films of Flying Null (UK), 3M Intelligent Transportation Systems (US), SCipher TSSI (UK), etc. Magnetic assembly can also be used, such as the technologies of Scientific Generics (UK). The self-generation RFID technology of Siemens Roke Manor Research can also be employed.

Any of these chips may be read-only chips, which include a fixed electronic code, or they may be read-write chips, which allow new information to be added. The chips may also be associated with sensors to read sensor information and transmit a signal responsive to the information, such as a value from a biosensor. Exemplary smart labels including RFID technology associated with a sensor are the active labels of KSW Microtec (Dresden, Germany), including TempSens® active smart labels for measuring and recording temperature. KSW Microtec also offers smart labels produced by flip chip assembly methods.

RFID tags can take many physical formats, such as a microchip from 30 to 100 microns thick and from 0.1 to 1 mm across, joined to a minute metal antenna such as the Hitachi 2.45 GHz Mew chip, or they can be in the form of deposited alloys 0.5 to 5 microns thick on a 20 micron polyester ribbon 1 mm across as used in some banknote security ribbons. Another form is the "Coil-on-Chip" system from Maxell (Tokyo, Japan), which is a 2.5 mm square IC with an antenna coil mounted directly on the chip. The chip is a read-write chip with 108 bytes of storage.

In addition, related devices such as the PENI tag of the University of Pittsburgh can also be considered a means for identifying objects wirelessly.

Exemplary RFID vendors include Matrics, Intermec, Alien Technology, Philips Semiconductor, and Texas Instruments. Manufacturing can be done by robotic techniques (e.g., "flip-chip"/"pick and place" techniques), fluidic self-assembly (FSA), the Philips "I-connect" method or the Philips "vibratory assembly" method, the Matrics PICA system (Parallel Integrated Chip Assembly, as described in the news item "New High-Speed RFID Tag Machine," RFID Journal, Sept. 19, 2003, available online for subscribers at or other known processes. (See also L. Frisk, J. Jarvinen, and R. Ristolainen, "Chip on Flex Attachment with Thermoplastic ACF for RFID Applications," Microelectronics Reliability, 42(9-11): 1559-1562 (Sept.-Nov. 2002)). Also of potential use for tracking and finding objects is the "mu-chip" of Hitachi with a built-in antenna on a sub-millimeter chip having a 128-bit serial number, as described by Jonathan Collins, "Hitachi Unveils Integrated RFID Tag," RFID Journal, Sept. 4, 2003, available at Exemplary RFID reader manufacturers include Intermec Technologies, Symbol Technologies, Matrics, AWID (e.g., their multi-protocol reader that can operate at various frequencies), and others. Software systems to support RFID systems are provided by IBM Global Services (which has acquired PriceWaterhouseCoopers), Texas Instruments, Manhattan Associates, and others. Printed RFID labels can be made using equipment from Zebra Technologies and other vendors.

Readers may also be integrated into or added onto a laptop, a PDA device, a cell phone, or other electronic device. Suitable readers may include the readers of AWID or the RFID reader on a compact flash card marketed by Syscan International for reading 13.56 MHz ISO-compliant tags or for other frequencies, as described in the news item, "Get RFID Readers in a Flash (Card)," RFID Journal, April 22, 2003, available online for subscribers at

Chip-based RFID systems need not be limited to silicon chips, but can also include printed electronics, particularly polymer electronics (organic electronics) such as organic field effect transistors (OFETs), and other technologies. Principles of polymer electronics are given by J. M. Shaw and P. F. Seidler, "Organic Electronics: Introduction," IBM Journal of Research and Development, Vol. 45, No. 1, 2001 ( See also PCT publication WO 99/19883, published April 22, 1999 by S. Babinec et al. of Dow Chemical. A representative manufacturer of printed electronics technology is Precisia, LLC (Ann Arbor, Michigan), a business unit launched by Flint Ink (Ann Arbor, Michigan). Precisia, LLC produces printed electronics for RFID systems, including smart packaging, lighting, and displays. Conductive inks manufactured by Precisia, LLC including conductive particles of silver or carbon have been proposed for use in printed RFID antennas. Such inks can be applied by screen printing, flexographic printing, lithographic printing, gravure printing, ink-jet printing, and the like. Plastic Logic (Cambridge, England) is another firm producing printable electronics suitable for RFID applications.

Other components associated with RFID systems can also include polymer electronics or printed electronics. For example, display graphics can include organics LEDs (OLEDs), printed electroluminescent displays, printed organics application specific integrated circuits (organic ASICs), polymer thin film transistors (pTFTs), the light-emitting polymers (LEPs) of Dow Corporation (see and Apply. Phys. Letters, Vol. 77, 2000, p. 406), and the like.

Power sources may include printed batteries, such as those produced by PowerPaper (Einat Israel--see or Cymbet Corp. (Elk River, Minnesota--see, or may rely on energy harvesting techniques that convert RF energy into useful electrical energy.

RFID tags can be assembled using flip chip technology, in which chips from an RFID wafer are inverted and placed in contact with an antenna. Exemplary processes include the Matrics PICA process for chip attachment to the antenna.

The RFID system may follow the systems proposed by the MIT Auto-ID Center, including the use of an electronic product code (EPC); a Savant system to manage the codes being read with a distributed architecture and processes such as data smoothing, reader coordination, data forwarding, data storage, and task management; and Object Name Service (ONS) for matching EPC information to item information, typically using a Domain Name Service (DNS) to route computers to Internet sites; and Physical Markup Language (PML) to describe information about a product.

Other vendors of integrated RFID systems or other tools for RFID include CheckPoint Systems, Tyco Sensormatic, Escort Memory Systems, Psion Teklogix (particularly for software systems to assist in logistics), SAMSys Technologies, Savi Technology, SCS Corporation, TAGSYS, ThingMagic LLC, and others. Supply-chain software can be provided by Crimson Software, Descartes Systems, EXE Technologies, Globe Ranger, Manhattan Associates, IBM Global Services, SAP, and others. RFID readers include those of Alien Technology, Matrics, Intermec, iPico, and AWID (Applied Wireless Identification Group, Hollister, California).

The tag may be provided by the manufacturer, a vendor, or others, and may be embedded in the object, attached to the surface of the object by a label or adhesive means, or be otherwise physically associated with the object. The RFID tag may have a unique electronic product code or other code, or optionally may include more extensive information.

Finally, an alternative to typical low-range readers is to use long-range readers with directional antennas that sweep selected areas to identify objects based on their RFID code. For such systems, highly sensitive electronics can be used to resolve faint signals at larger distances. By using advanced antennas in particular, RFID tags may, in some cases, be read from larger distances than previously recognized. The US military, for example, has developed sensitive electronics to extend the read range of passive RFID tags to large distances, as described in the article, "RFID Sensors: From Battlefield Intelligence To Consumer Protection," RFID Journal, Aug. 12, 2002, available online at Such ultra-sensitive radio frequency receivers rely on filtering systems to separate the RFID signal from background noise.

One antenna technology that may be particularly useful in amplifying weak signals and determining the direction of a radio signal source is smart antenna technology, such as adaptive antenna arrays including a plurality of antennas cooperatively associated with processors that continually readjust the radio signals from each of the antennas to create radio systems with extremely precise directionality and the ability to greatly amplify detected signals. Basic information about such smart antenna systems is provided by Martin Cooper in "Antennas Get Smart," Scientific American, Vol. 289, No. 1, July 2003, pp. 49-55. Further information is given by Martin Cooper and Marc Goulburg, "Intelligent Antennas: Spatial Division Multiple Access," 1996 Annual Review of Communications, pp. 999-1002 (see; in Joseph C. Liberti and T.S. Rappapport, Smart Antennas for Wireless Communications: IS-95 and Third Generation CDMA Applications, New York: Prentice Hall, 1999; and in various papers available at By way of example, manufacturers of adaptive antenna arrays include ArrayComm (San Jose, California) and Lucent Technologies (Murray Hill, New Jersey). Other antenna arrays can also be used, such as switched-beam arrays. Other beam-forming and beam steering technologies can be applied as well, such as the directional steerable antenna systems of Antenova Ltd. (Cambridge, England, see

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