US20140266624A1

US20140266624A1 - Wearable Authentication Device

Info

Publication number: US20140266624A1
Application number: US14/029,155
Authority: US
Inventors: James A Van Bosch; Pavel A. Shostak
Original assignee: Motorola Mobility LLC
Current assignee: Google Technology Holdings LLC
Priority date: 2013-03-15
Filing date: 2013-09-17
Publication date: 2014-09-18
Also published as: US20140263648A1; US9858450B2; EP2974218A1; CN105122768B; CN105122768A; WO2014143965A1; EP2974218B1

Abstract

Conventional Near Field Communication (NFC) authentication devices sometimes waste their users' time by requiring users to repeatedly reorient the devices to an NFC reader to complete authentication. To reduce the need for this reorientation, the present inventors, devised, among other things, an authentication assembly including two or more antennas configured for connection to a single NFC-tag circuit. In some embodiments, the assembly is built into an adjustable ring that can authenticate a user to an NFC-equipped electronic device, for example a smart phone, associated with the ring. In this configuration, each of the antennas generate a magnetic field generally perpendicular to an outer surface of the ring when excited with an appropriate signal, providing the ring with multiple options for establishing an inductive coupling to an NFC sensor in the electronic device without requiring the user to reorient the ring.

Description

RELATED APPLICATION

The present application claims priority to U.S. Provisional Patent Application 61/792,647, entitled WEARABLE AUTHENTICATION DEVICE, which was filed on Mar. 15, 2013, and which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Various embodiments disclosed herein concern wearable authentication devices, such as those incorporating Near Field Communications (NFC) technology.

BACKGROUND

Near Field Communications (NFC) is a short-range wireless communications technology standard that relies on inductive coupling of two devices to transfer information over a short range of 10 centimeters (approximately 4 inches) or less. Recent years have witnessed growing usage of NFC technology in smart phones, key fobs, credit cards, and other devices, not only because of its high convenience and low cost, but also because its extremely short range makes it resistant to interception For example, this technology has been used to enable users to use their NFC equipped smart phones to make electronic payments by touching their phones to an NFC reader, to swap contact information by touching their phones to other NFC-equipped smart phones, or to unlock their phones by touching an NFC tag.
One problem the present inventors have recognized is that some devices incorporating NFC technology require users to try multiple times to get an NFC reader to read or detect the presence of their NFC device. The problem, similar to trying to insert, a key upside down into a conventional door lock, is that many users are presenting their NFC-tagged devices in a backward, sideways, or other incorrect orientation that prevents the devices from being read or recognized, thus requiring these users to repeatedly reorient their devices and re-present them for reading until successful or the users give up.
Not only is this time consuming and potentially frustrating, it is also potentially dangerous for users wanting to call for emergency assistance or to open a ear or house door for personal safety. Moreover, if the NFC-tagged device is actually worn by the user, for example, as a watch, ring, or necklace, its reorientation may require use of two hands, rather than one, presenting additional inconvenience and potential hazards.
Accordingly, the present inventors have identified a need for improved. NFC-enabled devices, particularly wearable ones.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of authentication assemblies, wearable authentication devices, and related kits and/or systems are described below with reference to the following attached figures, none of which are drawn to scale. These figures are annotated with reference numbers for various features and components, and these drawings and numbers are used in the following description as a teaching aid, with like numbers referring to the same or similar features and components.

FIG. 1 is a plan view of an assembly for a wearable authentication device corresponding to one or more claimed embodiments.

FIG. 2 is a cross-sectional view of the FIG. 1 assembly through plane 2-2 and thus also corresponding to one or more embodiments.

FIG. 3 is a perspective view of wearable authentication device incorporating the FIG. 1 assembly and corresponding to one or more embodiments.

FIG. 4 is a cross-sectional end view of a FIG. 3 device taken along plane 4-4 and corresponding to one or more embodiments.

FIG. 5 is a block diagram of a kit or system which corresponds to one or more embodiments.

DETAILED DESCRIPTION

This document, which incorporates the drawings and the appended claims, describes one or more specific embodiments of one or more inventions. These embodiments, offered not to limit but only to exemplify and teach the invention(s), are shown and described in sufficient detail to enable those skilled in the art to implement or practice the invention(s). Thus, where appropriate to avoid obscuring the invention(s), the description may omit certain information known to those of skill in the art.

Overview

To address one or more problems with conventional NFC authentication devices, such as the necessity to reorient authentication devices to an NFC reader or sensor for authentication, the present inventors, devised, among other things, one or more assemblies, devices, systems and kits incorporating NFC authentication technology that promise a higher likelihood of first-time authentication. For example, one embodiment of a wireless authentication assembly includes two or more electrically connected NFC-compliant antennas configured for connection to a single NFC-compliant integrated circuit. In some embodiments, the assembly is configured as adjustable wearable authentication device, such as a ring, that can be worn by a user to authenticate the user to an NFC-equipped electronic device associated with the ring. In this configuration, each of the NFC-compliant antennas, which for example take the form of a planar spiral-wound coil, generates a magnetic field generally transverse or more particularly perpendicular, to an outer surface of the ring when excited with an appropriate RF signal, thereby providing the ring with multiple options for establishing an inductive coupling to the electronic device.

Example Assembly

FIG. 1 shows a plan view of an assembly 100 for a wearable authentication device compatible with one or more NFC, RFID, or other inductive-coupling communication standards. Assembly 100 includes a substrate 110, an antenna conductor 120, and a communications integrated circuit (IC) (or NFC tag IC) 130.
Substrate 110 has a length L of generally 60-80 millimeters and a width W of 7-10 millimeters. In the example embodiment, the substrate includes multiple layers which are shown best in the cross-sectional view of FIG. 2 taken along plane 2-2 in FIG. 1. Specifically, the layers, which are formed sequentially one atop the other using known techniques, such as deposition, or alternately as separate layers that are subsequently adhered or laminated, include a metal base layer 112, a ferrite shield layer 114, and an insulative layer 116.
Metal base layer 112 is approximately 0.4 millimeters thick, consists of a flexible, manually bendable metal, such as tin. Metal base layer 112 is adhered or laminated or otherwise joined to or deposited on ferrite shield layer 114, which has a thickness of approximately 0.1-0.2 millimeters. Ferrite shield layer 114, which in some embodiments comprises an iron-impregnated flexible plastic, such as mylar, provides a magnetic shielding function. Ferrite shield layer 114 supports and is adhered to insulative layer 116. In the example embodiment, insulative layer 116 is approximately 0.1-0.2 millimeters thick and is formed of a molded mylar or other flexible and durable plastic or polymer. Insulative layer 116 supports antenna conductor 120.
Antenna conductor 120 includes inductive coil elements 121, 122, 123 and 124 connected in series between terminal nodes 126 and 127. Inductive coil elements 121, 122, 123 and 124, which are spaced approximately 2-4 millimeters apart, take the form of flat rectangular spirals arranged according to the right-hand rule to produce corresponding magnetic fields transverse, for example substantially perpendicular to the surface of the insulative layer 116 (out of the page of FIG. 1) when conducting an electrical current in a counterclockwise direction as indicated via arrow heads 125. FIG. 2 shows this counterclockwise current flow with conductors 122A having current flow out of the page as indicated via the arrow points in the conductor cross-sections and with current flow into the page as indicated via the+arrow tails. The resulting magnetic field generated by this field is shown to exhibit magnetic field lines 128, which are generally transverse to plane defined by conductors 122A and 122B of coil element 122. The other coil elements behave similarly when excited. In the example embodiment, the series of coil elements is designed to present a total impedance at nodes 126 and 127 that is compatible with a conventional or standard NFC tag IC. In other words, the series of coils appears electrically as a single conventional NFC antenna coil to a standard NFC tag IC. However, some embodiments may use coil geometries and materials that exhibit a non-standard impedance for use with standard or non-standard NFC tag ICs.
In the example embodiment, the rectangular coils, which are substantially identical in geometry, optimized for resonance at 13.56 megahertz, each have an outermost loop that defines a CL by CW rectangle, with 4 progressively smaller and concentric rectangular turns or convolutions. The smallest or innermost turn defines a 0.5CL by 0.75CW mm rectangle. (Some embodiments use oval, circular, or other spiral geometries.) The example geometry uses uniformly wide 0.25-0.5 millimeter gold, silver, copper, aluminum, or non-metallic conductors with 0.25-0.5 millimeter center-to-center spacing. In some embodiments, the coil and insulation layers are formed as a flexible printed circuit, with the coil conductors having thickness in the range of 30-100 microns. In the presence of a changing magnetic field, an antenna signal voltage is induced across terminal nodes 126 and 127, which are coupled to respective contact pads or regions 131 and 132 of communication IC 130.
Communication IC 130, which in the example embodiment takes the form of a commercially available NFC tag IC, includes, among other things, a transceiver circuit 134 and a memory 135. Transceiver circuit 134 is configured not only to recognize 13.56 megahertz signals presented by antenna conductor 120 at contact pads 131 and 132, but also to communicate one or more portions of data stored in memory 135, for example authentication data, as a modulated 13.56 megahertz RF signal through antenna conductor 120 to an adjacent NFC reader, such as an NFC-equipped device (not shown in this figure). Memory 135 stores authentication data or information 136. The data, which may be encrypted in some embodiments, includes a unique device identifier from the TAG IC of the wearable authentication device. The device data that corresponds to the wearable authentication device may also include any other type of user and/or device identifying features, information, and data, such as a ring or wrist size, that is unique to the user who wears or owns a device including the assembly. In the example embodiment, communications IC 130 is positioned at one end or alternatively between two of the inductive elements. Some embodiments may mount the communications IC in the central region of one of the inductive elements.
In various embodiments, communications IC or NFC tag IC 130 is compatible with one or more NFC Forum Type 1, Type 2, Type 3 Type 4 or Type MIFARE Classic Tag standards and/or one or more of the International Standard Organization (ISO) standards: ISO/IEC14443 or with the Japanese Industrial Standard (JIS) X 6419-4. As such, the memory, in the example embodiment, ranges in capacity from 48 bytes to 1 megabyte and the transceiver supports communication speeds from 106 kbits/s to 424 kbits/s. However, other embodiments support alternative forms of inductive coupling and tag memory storage and communications protocols.

Example Device

FIGS. 3 and 4 show an example wearable authentication device 300 which incorporates the teachings of FIG. 1 and takes an annular or ring-like configuration sized for a human finger or other body part. In other embodiments, device 300 takes the form of a watch, a wristband, a chain necklace, a belt and buckle, and/or other type of wearable item.
More specifically, device 300 includes an outer layer or covering 310, assembly 100′ (an annular and extended form of assembly 100 in FIG. 1), transverse magnetic field regions 321-325 and a gap 330.
Outer layer or covering 310, shown best in the cross-sectional view of FIG. 4 taken along plane 4-4 in FIG. 3, serves as an encapsulating layer over the annular-configured assembly 100′, protecting it from environmental dirt, oil, and moisture. In some embodiments, the outer layer also covers the inner surfaces of assembly 100′ and gap 330. In the example embodiment, outer layer 310 is formed of a non-metallic material, such as mylar plastic, silicone, latex, polyurethane, or other suitable material, to permit the passage of wireless signals between the antenna and the associated device. It is envisioned that the outer material could be metallic in areas where the antenna coils need not emit, and non-metallic in areas around the coils.
Assembly 100′, in this ring-like configuration, has five coil elements 121, 122, 123, 124, and 124′ distributed equally and circumferentially underneath covering 310. When the conductors are conducting an electrical current provided by tag IC 130 (not visible in this cross-sectional view), the coils respectively generate, according to the right-hand rule, corresponding local magnetic fields 321, 322, 323, 324, and 325 through and above covering 310. Each of these fields is not only transverse to, but also perpendicular to a corresponding surface portion of covering 310 and to a plane defined by its associated coil element.
Providing more than one magnetic field with this orientation provides multiple opportunities for effective inductive coupling of the ring to an NFC reader in an associated device, thereby increasing the probability of an effective authentication occurring during a given presentation of the ring or wristband to the associated device. This is particularly true where the associated device is a handheld device, such as a smart phone that has an NFC sensor positioned near its back surface, and the authentication device takes the form a ring worn on a finger of a user's hand holding the phone in a conventional manner. In this position, the ring will rest against the back surface of the handheld device and provide sufficiently strong fields that match or nearly match what is desired for peak or optimal inductive coupling to the NFC sensor.
Gap 330, which is formed between two ends of the annular configured assembly 100′, is of an adjustable width, allowing changing the effective outer and inner circumferences of the device 300 and thus enabling the device to fit a range of finger sizes, or in the case of wristband or watchband embodiments to fit a range of wrist sizes. In some embodiments, gap 330 may be defined by overlapping the ends of assembly 100′, such that one end has a greater radial distance from a center of the device than does the other end, assuming a substantially circular configuration.

Example System & Kit

FIG. 5 shows an example kit or system 599, which includes wearable authentication device 300 of FIG. 3 and an electronic device 500. Electronic device 500 is generally representative of a personal computer, desktop computer, laptop computer, tablet computer, workstation, personal digital assistant, smart phone, mobile telephone, handheld navigation device, global positioning receiver, gaming system, media playback device, remote controller, vehicle steering wheel or structure, door handle or knob, joy stick, or any electronic device or assembly having an NFC or similar wireless communication capability and one or more features or functions for which authentication is required or desired as a prerequisite for user operation or access. Specifically, device 500 includes a central bus 501 which interconnects a power module 510, a transceiver module 520, a user interface module 530, a camera module 540, a processor module 550, a memory module 560, and NFC circuitry 570.
Power module 510 includes components and circuitry for providing power to various components of the electronic device 500. In the example embodiment, module 510 includes a power supply, one or more batteries, battery-charging circuitry, and an AC adapter module and plug (none of which are shown separately in the figure).
Transceiver module 520 includes one or more transceivers, transmitters, and/or receiver circuits for enabling communications with external devices, systems, and/or networks via available communications protocols. Some embodiments include circuitry for enabling personal area, local area, wide area, or metropolitan area wireless communications via one or more of the following protocols: CDMA (Code Division Multiple Access), GSM (Global System for Mobile Communications), Bluetooth, WiFi, WiMAX, GPS (Global Positioning System), LTE (Long Term Evolution), and UMTS (Universal Mobile Telecommunications System). Transceiver module 520 may also include one or more antennae 521, which are configured according to any known or developed structures for radiating and/or receiving electromagnetic energy as desired for one or more of the wireless transceivers, transmitters, and/or receiver circuits.
User interface module 530 includes one or more displays, one or more microphones, keyboards, alpha-numeric keyboard, pointing devices, isolated buttons, soft and/or hard keys, touch screens, jog wheel, and/or any other known input device. Additionally, user interface module includes one or more alert elements such as a loudspeaker, electronic display, and/or vibrator for creating audible, visible, and/or tactile alerts.
Camera module 540 includes one or more light or optical sensors, for example in the form of one or more arrays of image sensors. In some embodiments, the multiple image sensors are arranged to collect data from opposite directions, such as on the front and rear major surfaces of an apparatus housing.
Processor module 550 includes one or more processors, processing circuits, or controllers. In the example embodiment, processor module 550 takes any convenient or desirable form.
Memory module 560 takes the example form of one or more electronic, magnetic, or optical data-storage devices that stores code (machine-readable or executable instructions.) Specifically, memory module 560 stores code for operating system module 561, applications module 562, and NFC module 563.
In the example embodiment, operating system module 561 takes the form of a conventional operating system (OS), such as Google Chrome OS, Android OS, Apple OS X, Apple iOS, Microsoft Windows, Microsoft Windows Mobile, or Linux.
Applications module 562 includes one or more applications, such as a banking application or payment application, an email application, a presentation application, a telephony application, a text messaging application, and a game application, one or more of which may require detection of a NFC compliant authentication device prior to providing access to one or more portions of its functionality. As such, one or more of these applications directly and/or indirectly through use of capabilities of operating system 561 or through NFC interface module 563 communicate and/or otherwise collaborate with NFC circuitry 570 to implement the desired NFC authentication. In the exemplary embodiment NFC interface module 563 includes instructions for communicating with and/or programming one or more portions of NFC circuitry 570, such as NFC memory 571.
In addition to NFC memory 571 which stores authentication data 572, NFC circuitry 570 includes an NFC integrated circuit chip 573 and a NFC compliant antenna 575. NFC IC chip 573 includes, among other things, an NFC transceiver 574, which not only senses and decodes induced electrical signals supplied by antenna 575 but also excites antenna 575 with appropriate electrical signals representative of authentication data 572. In one example embodiment, authentication data 572 is factory configured or written to match the authentication data stored on authentication device 300.
In some embodiments, electronic device 500 can be configured, for example at an initial start up or through a set up menu, to generate and store authentication data (within NFC interface module 563) in NFC memory 571 and to direct NFC circuitry 570 to write the generated authentication data to device 300. In some embodiments, device 300 may be preconfigured with authentication data and upon a first reading by NFC circuitry 570, NFC interface module 563 prompts the user with a question of whether she desires to pair the authentication device with the electronic device, or with one or more applications or portions of applications within applications module 562 or with one or more features or functions of operating system 561.

CONCLUSION

This document describes specific embodiments of one or more inventions. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention(s) as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present teachings.
The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The scope of any invention described herein is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.
Moreover in this document, relational terms, such as second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” “has”, “having,” “includes”, “including,” “contains”, “containing” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, has, includes, contains a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by “comprises a”, “has . . . a”, “includes . . . a”, “contains . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises, has, includes, contains the element. The terms “a” and “an” are defined as one or more unless explicitly stated otherwise herein. The terms “substantially”, “essentially”, “approximately”, “about” or any other version thereof, are defined as being close to as understood by one of ordinary skill in the art, and in one non-limiting embodiment the term is defined to be within 10%, in another embodiment within 5%, in another embodiment within 1% and in another embodiment within 0.5%. The term “coupled” as used herein is defined as connected, although not necessarily directly and not necessarily mechanically. A device or structure that is “configured” in a certain way is configured in at least that way, but may also be configured in ways that are not listed.
It will be appreciated that some embodiments may include one or more generic or specialized processors (or “processing devices”) such as microprocessors, digital signal processors, customized processors and field programmable gate arrays (FPGAs) and unique stored program instructions (including both software and firmware) that control the one or more processors to implement, in conjunction with certain non-processor circuits, some, most, or all of the functions of the method and/or apparatus described herein. Alternatively, some or all functions could be implemented by a state machine that has no stored program instructions, or in one or more application specific integrated circuits (ASICs), in which each function or some combinations of certain of the functions are implemented as custom logic. Of course, a combination of the two approaches could be used.
Moreover, some embodiments can be implemented as a computer-readable storage medium having computer readable code stored thereon for programming a computer (e.g., including a processor) to perform a method as described and claimed herein. Likewise, computer-readable storage medium can include a non-transitory machine readable storage device, having stored thereon a computer program that include a plurality of code sections for performing operations, steps or a set of instructions.
Examples of such computer-readable storage mediums include, but are not limited to, a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a ROM (Read Only Memory), a PROM (Programmable Read Only Memory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically Erasable Programmable Read Only Memory) and a Flash memory. Further, it is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs and ICs with minimal experimentation.
The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter

Claims

What is claimed is:

1. An assembly for a wearable authentication device, the assembly comprising:

a substrate having a substrate surface;

first and second contact nodes for connection to an NFC tag component; and

an antenna conductor having first and second terminal nodes coupled to the first and second contact nodes, the antenna conductor including at least first and second inductive coils coupled between the first and second terminal nodes and supported by a corresponding portion of the surface, each coil configured to generate a magnetic field generally transverse to its corresponding portion of the surface in response to a compatible NFC excitation signal.

2. The assembly of claim 1, wherein each of the inductive coils is configured as a planar coil.

3. The assembly of claim 1, wherein the first and second inductive coils are coupled in series between the first and second contact nodes.

4. The assembly of claim 1, wherein each coil is configured to generate a magnetic field generally perpendicular to its corresponding portion of the surface in response to a compatible NFC excitation signal.

5. The assembly of claim 1, further comprising an NFC tag circuit coupled to the first and second contact nodes.

6. The assembly of claim 5, wherein the NFC tag circuit is a passive NFC tag circuit.

7. The assembly of claim 1, wherein the substrate comprises:

an insulative layer containing the antenna conductor;

a base layer for contacting the skin of a user; and

a ferrite layer between the insulative layer and the base layer.

8. The assembly of claim 1, wherein the substrate is configured as a ring-like structure.

9. The assembly of claim 8, wherein the ring-like structure includes a gap defined by first and second ends of the substrate, with the gap being adjustable to change an effective circumference of the ring-like structure.

10. A system comprising:

an electronic device having an NFC sensor, with the NFC sensor having a memory storing a representation of an authentication code; and

a wearable authentication device including:

an NFC tag circuit including a memory storing a representation of the authentication code, and first and second contact nodes; and

an assembly including:

a substrate having a substrate surface;

first and second contact nodes for connection to an NFC tag component; and

11. The system of claim 10, wherein each of the inductive coils is configured as a planar coil and coupled in series between the first and second contact nodes.

12. The system of claim 10, wherein each coil is configured to generate a magnetic field generally perpendicular to its corresponding portion of the surface in response to the NFC excitation signal.

13. The system of claim 10, wherein the NFC tag circuit is a passive NFC tag circuit.

14. The system of claim 10, wherein the substrate comprises:

an insulative layer containing the antenna conductor;

a base layer for contacting the skin of a user; and

a ferrite layer between the insulative layer and the base layer.

15. The system of claim 14, wherein the substrate is configured as a ring-like structure.

16. The system of claim 8, wherein the ring-like structure includes a gap defined by first and second ends of the substrate, with the gap being adjustable to change an effective circumference of the ring-like structure.

17. A wearable authentication device comprising:

an integrated NFC tag circuit having first and second contact nodes; and

first and second planar coil antennas electrically coupled to the first and second contact pads, with each coil antenna configured to generate, in response to an excitation signal from the tag circuit, a magnetic field generally transverse to a plane defined by the coil antenna.

18. The device of claim 17, wherein the magnetic field is substantially perpendicular to the plane defined by the coil antenna.

19. The device of claim 17, wherein the first and second coil antennas are coupled in series between the first and second contact nodes.

20. The device of claim 23, further comprising a substrate configured as a ring-like structure, with the first and second coil antennas attached to the substrate, opposite each other.

21. A method comprising:

exciting a first NFC antenna element with an interrogation signal; and

driving, in response to the interrogation signal, the first NFC antenna element and a second NFC antenna to provide respective first and second responsive magnetic fields, with the first and second NFC antenna elements coupled to an NFC driver circuit.

22. The method of claim 21, wherein the first and second antenna elements are coupled in series between first and second contact nodes of an NFC tag circuit.

23. The method of claim 21, wherein the first and second antenna elements are configured as respective first and second flat spirals and supported by a common substrate.

24. A kit comprising:

an electronic device having an NFC sensor, with the NFC sensor having a first memory storing for a representation of an authentication code; and

a wearable authentication device including:

an NFC tag circuit including a second memory for storing a representation of the authentication code, and first and second contact nodes; and

an assembly including:

a substrate having a substrate surface;

first and second contact nodes coupled to the NFC tag circuit; and

an antenna conductor having first and second terminal nodes coupled to the first and second contact nodes of the NFC tag circuit, the antenna conductor including at least first and second inductive coils coupled between the first and second terminal nodes and supported by a corresponding portion of the surface, each coil configured to generate a magnetic field generally perpendicular to its corresponding portion of the surface in response to an NFC excitation signal generated by the electronic device.

25. The kit of claim 24, wherein each of the inductive coils is configured as a planar coil and coupled in series between the first and second contact nodes.

26. The kit of claim 24, wherein the substrate is configured as a ring-like structure having an adjustable effective circumference and comprising:

an insulative layer containing the antenna conductor;

a base layer for contacting the skin of a user; and

a ferrite layer between the insulative layer and the base layer.

27. The kit of claim 24, wherein the electronic device includes means for programming the first memory and the second memory to include matching authentication codes.