Electronic tag

Abstract

To provide a capacitive coupled tag and a method of operation that overcome conventional problems.SOLUTION: A capacitive coupled radio frequency identification, an RFID, a tag, and a method for reading the tag are provided, the tag comprising a semiconductor substrate having a first planar surface and a second planar surface distal from the first planar surface. A metallic pad is formed on the first planar surface of the semiconductor substrate. A circuit is formed on the semiconductor substrate and electrically connected to the metallic pad and the second planar surface of the semiconductor substrate. The circuit is configured to respond to a radio frequency (RF) input signal by providing a data signal encoded by varying an impedance between the metallic pad and the second planar surface of the semiconductor substrate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a capacitively coupled RFID tag and a method for its operation. [Background technology]

[0002] Capacitively Coupled Tags (CC Tags or CCT) provide reliability and tracking capabilities while offering improved security. This technology is widely used for tracking artifacts where security and reliability are key. However, if the size of CC tags can be reduced and their efficiency increased, then the number of potential applications will increase.

[0003] Other types of RFID tags exist, which may include an antenna to receive RF signals from a reader to power the device and to respond with a signal using the same antenna. However, the use of such antennas may increase the size and manufacturing complexity of the device, thus limiting their applications. Furthermore, such antennas may introduce points of failure, resulting in less robust devices. CC tags do not use antennas, but interact with the RF signal provided by a reader by changing the impedance of the tag, which affects the electric field generated by the reader and is in turn detected by the reader. When such impedance changes are modulated, this modulation may be decoded to provide data (e.g., the CC tag's identifier).

[0004] "0.075 x 0.075 mm 2"Ultra-Small 7.5μm Ultra-Thin RFID-Chip Mounting Technology," Hideyuki Noda and Mitsuo Usami, 978-14244-2231-09 / 08, 2008 IEEE, 2008 Electronic Components and Technology Conference, pp. 360-370, describes the fabrication of small RFID chips including antennas. However, the fabrication of such RFID chips, especially in mass production, presents technical difficulties that can reduce yields and increase failure rates in the manufacturing process.

[0005] "Power RFID Chip Technology", Mitsuo Usami, Hitachi Ltd., 978-1-4244-2342-2 / 08, 2008 IEEE, pp. 1220-1223, describes another small RFID tag and its manufacturing method, which also requires an antenna structure mounted on the RFID chip, which limits the lower tag size.

[0006] "26.6-A 0.05 x 0.05 mm 2 "RFID Chip with Easily Scaled-Down ID-Memory", Mitsuo Usami, Hisao Tanabe, Akira Sato, Isao Sakama, Yukio Maki, Toshiaki Iwamatsu, Takashi Ipposhi, Yasuo Inoue, Hitachi, ISSCC 2007 / SESSION 26 / NON-VOLATILE MEMORIES / 26.6, 1-4244-0852-0 / 07, 2007 IEEE, pp. 482-483, describes an RFID chip that has a unique IP address and uses dual surface electrodes.

[0007] A further requirement is that the RFID tag be able to be read in the presence of other RFID tags, which can be particularly difficult for very small RFID tags that may be embedded in many separate items that are stacked or placed near each other. Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, there is a need for a capacitively coupled tag and method of operation that overcomes these problems. [Means for solving the problem]

[0009] Capacitively coupled RFID tags (CC tags or RFID tags) are provided that are thin (e.g., having a thickness of 100 μm, 50 μm or less) formed on a semiconductor substrate such as silicon, with one surface covered with a metal layer (e.g., gold on aluminum) and the other surface being a bare semiconductor surface, which together act as a tunable impedance. A circuit or chip (e.g., integrated circuit, IC) on or within the semiconductor substrate controls the device and changes its own electrical properties as seen (electrically) by an external reader that applies an electric field through the CC tag, typically using electrodes. The CC tag is powered by an externally applied RF field and responds to its own presence by changing its own electrical properties (in particular its own impedance). The CC tag capacitively couples to the reader, and the IC modulates its own electrical properties to encode a data signal that is decoded by the reader. The electrical properties are changed by changing the impedance between the metal layer and the opposing semiconductor layer.

[0010] When two or more such CC tags, or a stack, are placed within the electric field generated by the reader, only one of the CC tags is configured to respond. In an example implementation, the remaining CC tags can reduce their own impedance (e.g., statically) by, for example, applying a short between a metal surface and an opposing semiconductor surface, so that each CC tag can respond in turn and separately, and provide an output signal by modulating the RF input signal.

[0011] Also provided is a method of manufacturing a capacitively coupled RFID tag by providing a semiconductor substrate (e.g., silicon) having opposing planar surfaces, applying a metallic layer to one of the surfaces, and forming (e.g., using lithographic techniques) circuitry (e.g., CMOS circuitry) as described throughout this specification on or in the other planar surface. Preferably, the thickness (i.e., the distance between the opposing planar surfaces) is 50 μm (or 25 μm, 100 μm, or 150 μm) or less. The substrate can be square, rectangular, or another shape. Preferably, the substrate and resulting device are between 50 and 700 μm in width and / or length.

[0012] Applications of these concepts include, but are not limited to, banknotes, visas, stamps, official documents, holograms, foils, cigarettes and tobacco products of any kind (e.g., standard cigarettes and e-cigarettes), bottles, labels, food, food packaging, tablets, and other pharmaceutical products (including their coatings and packaging materials) and other types of packaging materials requiring such small, micron-thickness solutions. CC tags can be embedded or affixed to such items.

[0013] Against the previously described background, and according to a first aspect, there is provided a capacitively coupled radio frequency identification (RFID) tag (e.g., a CC tag), a semiconductor substrate having a first planar surface and a second planar surface distal to the first planar surface; a metal pad formed on the first planar surface of the semiconductor substrate; a circuit formed on the semiconductor substrate and electrically connected to the metallic pad and the second planar surface of the semiconductor substrate, the circuit configured to respond to a radio frequency (RF) input signal by providing a data signal that is encoded by varying an impedance between the metallic pad and the second planar surface of the semiconductor substrate; and Having one side provided with metal pads and the other side with a semiconductor surface reduces manufacturing complexity (e.g., more than a CC tag that may have metal pads on each side) since the semiconductor surface is provided by the substrate while the opposing surface allows for a capacitance that may be varied by changing the device impedance between the surfaces. The flat surface may be flat or curved (e.g., to accommodate the shape of an object having an attached tag), while not affecting the function of the tag, for example.

[0014] Preferably, the data signal may be encoded by the varying impedance between the metallic pad and the second planar surface of the semiconductor substrate to modulate the RF input signal, allowing the RF input signal to be used both to power the device and to be decoded by a reader.

[0015] Preferably, the RF input signal may be provided by an external reader.

[0016] Advantageously, said circuitry is further adapted to be powered by said RF input signal.

[0017] Advantageously, the circuitry may be further configured to decode a signal encoded within the RF input signal, and the data signal is provided in response to the decoded signal. The circuitry may optionally include a small amount of power storage (e.g. a capacitor) to store power generated by the RF input signal for a short period of time.

[0018] Optionally, the circuitry modulates the RF input signal by varying the frequency, amplitude and / or phase or any other electrical characteristic of the RF input signal.

[0019] Optionally, the circuitry may be formed on or embedded within the second planar surface of the semiconductor substrate.

[0020] Optionally, the circuit may be configured to vary the electrical impedance between the metallic pad and the second planar surface of the semiconductor substrate by applying a short between the metallic pad and the second planar surface of the semiconductor substrate.

[0021] Optionally, the distance between the outer surface of the metallic pad and the second planar surface of the semiconductor substrate is 50 μm or less. This may be described as the thickness of the CC tag. The thickness may alternatively be, for example, 10 μm or less, 25 μm or less, 100 μm or less, or 150 μm or less. The CC tag may have, for example, a substantially square or rectangular cross section.

[0022] Optionally, the circuitry may be further configured to detect the presence of one or more additional capacitively coupled RFID tags (e.g., of the same type) and, in response, cease providing the data signal. This prevents signal collisions and allows multiple CC tags to be read sequentially without having to have only one CC tag in range of the reader at a time.

[0023] Optionally, the circuitry may be configured to cease providing the data signal by applying a short between the metallic pad and the second planar surface of the semiconductor substrate, effectively making the "off" CC tag invisible (electrically) to a reader.

[0024] Optionally, the circuitry may be configured to cease providing the data signal until one or more further capacitively coupled RFID tags have provided their own data signal.

[0025] Optionally, said circuitry may be further configured to cease providing said data signal (ie of its own data signal) in accordance with an anti-collision protocol.

[0026] Optionally, said anti-collision protocol comprises: The one or more capacitively coupled RFID tags may be based on communication between them according to a random number generator or negotiated responses between them according to a predefined sequence of responses. Such anti-collision protocols may not rely on direct communication between the CC tags, but rather they may rely on communication via a reader or no communication at all.

[0027] Optionally, the first planar surface may be parallel to the second planar surface. Other configurations may be used where the surfaces give rise to capacitance.

[0028] Optionally, the capacitively coupled RFID tag is flexible. It can include a bending radius on the order of the width or length of the CC tag. Thus, the CC tag may be embedded or attached to flexible items with low risk of damage.

[0029] Optionally, the capacitively coupled RFID tag may further comprise a metal plate, which allows a reader electrode to be coupled to the side of the tag that does not face the reader, thus avoiding the need for a reader electrode on the opposite side of the tag.

[0030] Optionally, the capacitively coupled RFID tag may further comprise an insulator laminated between the tag and the metallic plate.

[0031] Optionally, the insulator may be laminated to the metallic pad of the tag, possibly by adhesive or another suitable method.

[0032] Optionally, the insulator may be laminated to the second planar surface of the semiconductor substrate.

[0033] Optionally, the metal plate may be curved, so that it can accommodate an article, for example a cylindrical article or a spherical article.

[0034] Optionally, the metallic plate may extend beyond at least one edge of the metallic pad and / or the semiconductor substrate.

[0035] According to a second aspect, there is provided an article having embedded therein the capacitively coupled RFID tag of the previous aspect.

[0036] Optionally, a surface of the article is parallel or substantially parallel to the first planar surface of the capacitively coupled RFID tag, which is useful for flat, planar objects and / or flexible objects.

[0037] Optionally, the article may be formed from paper, from a plastic material, and is a banknote, a passport, an ID card, a tax stamp, a cigarette, an e-cigarette, a label, a tablet (e.g., medicine), a drink capsule, a coffee capsule, a tea capsule, and / or a legal document.

[0038] According to a third aspect, there is provided a method of communicating with a plurality of capacitively coupled RFID tags, the method comprising: applying a radio frequency (RF) input signal to the plurality of capacitively coupled RFID tags; responding to the applied RF input by one of the plurality of capacitively coupled RFID tags by altering an impedance of the capacitively coupled RFID tag, the altering impedance encoding a data signal; detecting a variation in the RF input signal caused by the varying impedance of the one of the plurality of capacitively coupled RFID tags, the variation encoding the data signal; decoding said data signal from said variation of said RF input signal; Including, The non-responsive capacitively coupled RFID tags of the plurality of capacitively coupled RFID tags decrease their impedance while the one capacitively coupled RFID tag changes its impedance. Other methods of reading CC tags as mentioned above may be used.

[0039] Optionally, the variation of the RF input signal may be a variation in frequency, amplitude and / or phase.

[0040] Preferably, the method may further include the step of using an anti-collision protocol to determine which one of the plurality of capacitively coupled RFID tags responds to the radio frequency by changing its own impedance.

[0041] Optionally, the multiple capacitively coupled RFID tags may be stacked one above the other or otherwise placed in close proximity to one another.

[0042] According to a fourth aspect, there is provided a computer program comprising program instructions which, when executed on a computer, cause said computer to carry out the method described above.

[0043] According to a fifth aspect, there is provided a computer readable medium carrying a computer program as described above.

[0044] According to a sixth aspect, Any one or more of the capacitively coupled RFID tags described above; a reader having an RF signal generator and a decoder configured to decode a data signal; A system is provided comprising:

[0045] Optionally, the reader: a first electrode configured to align with the metallic pad and / or semiconductor substrate of the tag; a second electrode configured to align with the metallic pad and / or a portion of the metallic plate that extends beyond at least one edge of the semiconductor substrate; The system may further include, for example, a tag having a metallic plate that extends beyond the substrate and / or metallic pad.

[0046] Optionally, the metal plate may be formed from the metal packaging of a can, a tin can, a coffee capsule, a tea capsule or a beverage capsule, thus simplifying the manufacture of the device and allowing the tag to be more effectively used and applied to metallic articles.

[0047] Optionally, the first electrode and / or the second electrode may be curved, such that the electrodes can accommodate, for example, a cylindrical or spherical object (e.g., a cigarette or an e-cigarette).

[0048] The above described methods may be implemented as a computer program comprising program instructions for operating a computer. The computer program may be stored on a computer readable medium.

[0049] A computer system (e.g., implemented within an integrated circuit) may include one or more processors (e.g., local, virtual or cloud-based), such as a central processing unit (CPU), and / or a single or collection of graphic processing units (GPUs). The processor may execute logic in the form of a software program. A computer system may include memory, including volatile and non-volatile storage media. Computer-readable media may be included for storing logic and program instructions. Different parts of the system may be connected using a network (e.g., wireless and wired networks). A computer system may include one or more interfaces. A computer system may include a suitable operating system, such as, for example, UNIX, Windows (RTM) or Linux.

[0050] It should be noted that any of the features described above may be used in conjunction with any particular aspect or embodiment of the invention.

[0051] The invention can be put into practice in many ways and embodiments will now be described, by way of example only, and with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0052] [Figure 1] FIG. 2 is a schematic diagram of a capacitively coupled RFID tag being read by a reader. [Diagram 2] 2 is a schematic diagram of multiple capacitively coupled RFID tags of FIG. 1 being read by a reader. [Diagram 3] 1 is a schematic diagram of a further capacitively coupled RFID tag being read by a reader. [Figure 4] 1 is a schematic diagram of a further capacitively coupled RFID tag being read by a reader. [Diagram 5]FIG. 5 is a schematic diagram of a system including any of the capacitively coupled RFID tags and readers of FIGS. 1-4 applied to a cigarette or e-cigarette (or other object). [Figure 6a] 6 is a cross-sectional view of the capacitively coupled RFID tag of FIG. 5 when applied to a cigarette or e-cigarette. [Figure 6b] FIG. 6b is a schematic diagram of the cigarette or e-cigarette of FIG. 6a together with a reader electrode. [Figure 7] FIG. 2 is a schematic diagram of a further plurality of capacitively coupled RFID tags (each attached to an item) being read by a reader. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] It should be noted that the figures are illustrated for simplicity and are not necessarily drawn to scale, and similar features are given the same reference numerals.

[0054] According to an exemplary implementation, a capacitively coupled tag (CC tag) is a radio frequency identification system (RDID) based on a single integrated circuit (IC). In a typical application, the integrated circuit is a piece of single crystal silicon having one side functionalized through various steps to incorporate electronic components such as, but not limited to, resistors, capacitors, diodes, transistors, etc., connected via metal layers.

[0055] Due to the small size of these components, electrical connectivity to the integrated circuit is provided using the presence of several "pads" or metal layers large enough to connect with small wires or probes. These "pads" are usually located on the functionalized side of the integrated circuit.

[0056] The backside of an integrated IC is usually connected to a ground reference and is of no particular interest at the electronic level. In the present CC tag, one large metallic pad is placed on the functionalized side of the IC, and a second pad is provided on the backside of the device. This structure allows the device to be positioned freely on a surface without the need for any precise positioning or angular orientation, and the device can function regardless of which side of the surface the CC tag is deposited on. This important feature simplifies the deposition process and reduces the associated costs.

[0057] ICs can be formed using CMOS (complementary metal oxide semiconductor) technology (i.e., silicon-based technology). Due to the presence of both n-type and p-type MOS on the same silicon substrate, a well-known effect known as "latch-up" can occur. This can be caused by a parasitic thyristor inherently present in CMOS structures, which can be triggered by unexpected voltage spikes and create a short conduction between the positive and negative contacts of the device's power supply. This effect is typically reduced by placing a separate ground contact on the substrate. This effect can even be stronger in CC tags due to the presence of radio frequency (RF) signals coming from the backside pad (i.e., semiconductor), which can be connected to the virtual ground of the IC. To avoid this effect, a separate ground contact can be placed near the MOS transistor. Alternatively, other semiconductors can be used, such as, for example, gallium arsenide, graphene, germanium, and silicon carbide.

[0058] In this exemplary CC tag, the backside of the integrated circuit (i.e. the pure semiconductor substrate) is used as a potential electrical pad and is placed near a second larger pad on the top surface (opposite) of the functionalized surface. In this example, the structure takes the form of a thin plate (having a first surface and an opposite surface). The system consists of an integrated circuit with one pad on the top surface and one on the bottom surface (or vice versa depending on any particular orientation), the bottom pad may be used as a capacitor plate from a specially developed reader.

[0059] The reader can communicate with the CC tag via a modulated electric field (capacitive coupling) without requiring electrical continuity between the reader and the tag.

[0060] Standard RFID tags have an input stage consisting of an inductor acting as an antenna and a tuning capacitor tuned at the transmission frequency to optimize signal transfer. In contrast, CC tags only have a capacitor at the input stage. The capacitor exhibits short-circuit behavior at high frequencies, and the cut-off frequency at which this behavior is observed depends on the value of the capacitor itself and the value of the parasitic resistance of the circuit. This approach offers an important advantage, since the coupling capacitor just needs to be "high enough" to exhibit short-circuit behavior without requiring precise tuning of the capacitor itself. This results in a much lower dependence of process parameter fluctuations in the deposition process.

[0061] For the same reason, CC tags can even simultaneously operate at different frequencies, generally the higher the better.The solution shown in the figure (explained in more detail below) offers several advantages. - The tags are extremely simple to manufacture, cheap and very robust: they can be easily manufactured together with standard integrated circuit techniques. - The tag does not require special alignment with the article to be tagged, which in turn reduces manufacturing complexity and costs. - CC tags, when stacked, can also be read when the tags implement an anti-collision protocol for tags and readers.

[0062] The CC tags can be thinned to less than 50 μm, resulting in ultra-thin and flexible tags that can be encapsulated in a variety of applications such as, but not limited to, banknotes, official and government documents, tax stamps, visas, holograms, as well as any packaging material of any item, paper, etc.

[0063] FIG. 1 shows a schematic diagram of a capacitively coupled tag 10 (CC tag) that is powered and read by a tag reader 20. The tag reader 20 includes electrodes 30 that generate a radio frequency (RF) signal to create an electric field 70. This RF signal may be modulated and detected by the capacitively coupled tag 10. As shown in this figure, the upper surface or top side of the capacitively coupled tag 10 has an electrode 40 that is metallic. The opposite surface or bottom side of the capacitively coupled tag 10 is left bare and forms a semiconductor electrode surface 50. Within or on the surface of the semiconductor substrate of the capacitively coupled tag 10 is a circuit (i.e., an integrated circuit) 60 (not shown in detail in this figure). The electric field 70 is illustrated by arrows between the electrodes 30 of the reader 20. The metal may be aluminum, copper, gold, silver, or a combination of separate metal layers (e.g., gold on aluminum). The IC may be fabricated on or within the surface of the CC tag 10 that does not have a metallic pad (i.e., a semiconductor pad surface). Preferably, the surfaces are parallel and flat.

[0064] Figure 2 shows a further schematic diagram of multiple capacitively coupled tags 10 of the same configuration as shown in Figure 1. Again, a reader 20 applies an electric field between the reader's electrodes 30 to read each of the capacitively coupled tags 10. This diagram does not show any articles or substrates attached to each CC tag 10 to simplify the diagram, but this would be present. Figure 7 shows an equivalent arrangement with the article to be tagged attached to each CC tag 10 in the stack. It is noted that it is not necessary for the CC tags 10 to be perfectly aligned in order to be read by the reader.

[0065] When there is more than one CC tag 10 between the electrodes 30 of the reader, all but one CC tag 10 respond to the incident RF input signal by modulating it (i.e. by changing their own impedance to provide a data signal). The remaining CC tags can optionally reduce their own impedance, for example by shorting their own pads (metallic and semiconducting surfaces). This makes the CC tags electrically invisible to the reader. When the first CC tag is provided with its data signal, it stops modulating the input RF signal and shorts its own pads. Then another CC tag responds to the input RF signal by modulating the input RF signal as explained above. The process continues until all CC tags are provided with data. Thus, CC tags can be stacked one after the other without reducing the signal strength.

[0066] Separate CC tags can communicate with each other to determine which one responds to the signal. This can be achieved using an anti-collision algorithm, which can generate a random delay that results in a different time for each tag's transmission. Alternatively, no communication is required, and each CC tag can respond to an incoming RF signal after a different (e.g., random) delay, which substantially reduces the risk of any two CC tags responding simultaneously (the actual transmission time may be short compared to the delay time).

[0067] Shorting the pads may be accomplished, for example, by one or more transistors changing their state from "off" to "saturated" to act as an on / off switch.

[0068] Further alternative implementations may be used that may include any one or more of the following alternatives or advantages. The CC tag 10 can be embedded in or on the surface of ultra-thin structures (such as paper sheets, banknotes, holograms, postage stamps, etc.) without the need for any antennas, alignment or specific positioning. The CC tag 10 does not need a metallic contact with the reader. Radio frequency (RF) signals can travel from the reader to the CC tag 10 even through an insulating layer that is made thin (less than 1 mm). The CC tag 10 can draw power from the reader when the reader is within reading distance. The CC tag 10 can respond by modulating (on / off switching) the impedance between the top and bottom electrodes. · The CC tag 10 is much more robust to manufacturing parameter fluctuations since it does not work at circuit resonance and does not suffer from frequency detuning problems. The CC tag 10 can be read during lamination, either aligned with the laminate or capacitively coupled using a separate metal layer deposited onto the thin structure. · The CC tag 10 may be equipped with an anti-collision solution to prevent two or more tags from communicating with the reader at the same time. When CC tags 10 are stacked and read, they may follow the procedure below: It receives power and data from the reader for a certain period of time (the charging time).

[0069] If the tag is deemed to respond, it can modulate its own impedance to communicate with the reader.

[0070] If a tag is not expected to reply, it may lower the tag's output impedance to a low level (switched on) to allow the reader signal to pass through to tags that are targeted to reply.

[0071] When the CC tags 10 are read while stacked, they are electrically "in series" with each other. This means that the voltage across the stack is divided by the number of elements in the stack. The reader can provide an adaptive voltage to provide sufficient voltage or power to operate each CC tag 10. This may involve, for example, increasing the applied electric field (e.g., voltage and / or power) to a level such that all of the CC tags can be powered. It should be noted that the CC tags 10 may be placed in any orientation between the reader electrodes. For example, the first electrode may be raised or lowered, and the second electrode may be lowered or raised. Different CC tags 10 placed in a stack may be placed in any orientation, which may be different for CC tags 10 in the same stack.

[0072] The previous example describes a CC tag reading technique where a tag or a series of tags is "clamped" between or preferably placed close to two reader electrodes (e.g., parts of a reader). This approach is particularly applicable to articles to be tagged, such as thin structures like paper, bank notes, etc., on which the CC tag 10 is placed (as shown in FIG. 3 ), or in which the CC tag 10 is placed.

[0073] In a further exemplary implementation, a "single-sided" readout can be used. This exemplary implementation avoids the need to place reader electrodes on both sides of the article, and can therefore be used with larger or thicker objects. This is achieved by adding a separate metal layer (e.g., a suitable conductor such as aluminum, copper, silver or gold) behind the CC tag on the article, as shown in FIG. 4. Although FIG. 4 shows the CC tag positioned on the top side of the article, the CC tag can also be positioned on the side or underneath the article. The CC tag used in this exemplary implementation can be the same or substantially similar to those described above.

[0074] The metal layer extends beyond or overlaps the CC tag 10 in at least one direction. Two electrodes are again used with the reader. Electrode #1 is positioned above the CC tag 10 (and part of the metal layer) on the object. Electrode #2 is positioned above or in alignment with another part of the metal layer that substantially avoids the CC tag 10 but is not below or aligned with the CC tag 10. Thus, the electrodes can be positioned on the same side of the article and still allow capacitive coupling with the CC tag 10. In other words, the reader, CC tag and article are positioned with a first reader electrode, then the CC tag 10 (e.g., directly below the first electrode), then the continuous metal layer, then the article to be tagged. The second reader electrode is adjacent to the first electrode with the same metal layer between the second electrode and the article. In an example implementation, the CC tag 10 can be embedded or partially embedded in an insulator layer (e.g., a polymer or other dielectric) disposed on and substantially over a metal layer, as shown in Figure 4. The insulator layer (or a portion thereof) may be directly between the CC tag 10 and the metal layer.

[0075] Some example uses of the CC tag 10 are described above. A further example is the use of the CC tag 10 (of any type described above) in consumables such as electronic or e-cigarettes, beverage capsules, etc. Figure 5 shows an example implementation of this with the CC tag 10 integrated into a part of the e-cigarette (e.g. a replaceable part such as a tobacco plug or stick 510) and a reader (or in the example, a reader electrode 550) placed on another part of the e-cigarette 540. Thus, the reader can verify whether the e-cigarette has the presence of a correct or legal replacement part.

[0076] In this example, the conductive electrodes may be printed or incorporated into the paper, e.g., the outer packaging of the e-cigarette, with the CC tag 10 incorporated into either the hollow acetate tube or the polymer membrane filter. The reader electrode or electrodes 550 may be incorporated into the packaging tip (ejector side) of the e-cigarette. The reader electrode may, for example, be incorporated in the same volume as the existing control electronics of the e-cigarette.

[0077] In the exemplary system of Figure 5, the electrodes 520 may also be located on the tobacco plug 510. However, the CC tag 10 may also operate without such external electrodes. A printed circuit board 505 may be used to mount the various components of the system so that the reader electrodes 550 and associated contacts 530 may be coupled to the reader (e.g., using RF communications). These parts of the system may be housed within a case 580 and may be electrically coupled (e.g., using a USB connector 570) to provide data and power connectivity to a computer or microprocessor 560.

[0078] 6a shows in more detail how such a CC tag 10 can be formed with a cigarette or e-cigarette (or other cylindrical object) 605. This figure illustrates in schematic form how a metal backplane or metal plate 620 fits the curved surface (e.g., cylindrical) of the e-cigarette 605 and an insulating layer 610 that separates this metal plate 620 from the CC tag 10. This figure also shows the reader electrodes 630 surrounding the e-cigarette 605 and the CC tag 10.

[0079] Figure 6b illustrates diagrammatically how such a CC tag 10 (with a metal back electrode or backplane metal layer similar to that shown in Figure 4) can be read within a ring-shaped metal reader electrode (550, 550') that surrounds the cigarette or e-cigarette 605. Such an electrode operates in a similar manner to that described above.

[0080] Such CC tags 10 (i.e., those that can be read by a single-sided or adjacent electrode reader) can be more easily read when applied to articles such as labels, packaging materials, holograms, coatings (e.g., tablet coatings), other pharmaceuticals, and irregular or non-flat articles. Figure 6b shows how the metal plate 620 extends beyond the substrate and / or metal pads of the CC tag 10 such that one reader electrode 550' covers the metal plate 620 but not the rest of the CC tag 10, and the other reader electrode 550 covers the rest of the CC tag 10. The metal plate thus capacitively couples a signal to the far or opposite electrode of the CC tag 10 (i.e., to the other or opposite side relative to the side where the reader electrode is located).

[0081] While Figures 5, 6a and 6b are shown with the particular CC tag 10 described throughout this specification, similar configurations (i.e., electrode configurations) can be used with different capacitively coupled tags.

[0082] In example implementations, the metal plate can instead be formed from part or all of the article or object to be tagged. For example, the object can be a metal or foil capsule, a can, a tin can, or a carton with enclosed products. The article can be, for example, disposable or reusable. It can be a beverage capsule, coffee capsule, or tea capsule with an aluminum body. In these examples, the article itself (or at least the metal container) has the same function as the metal plate and can be capacitively coupled to one of the reader electrodes, avoiding the need for electrodes on both sides of the CC tag 10 and also improving the use of the CC tag 10 when applied to conductive articles.

[0083] The problem to be solved is the incorporation of capacitive tags and electrodes, consisting for example of capacitive chips, into tobacco sticks for mass production.

[0084] The back electrode of the capacitive tag can be incorporated (e.g., by printing or interweaving a metallic conductor) into the paper that is wrapped around the tobacco stick, the capacitive chip can be attached to the top of the electrode (alternatively with additional adhesive for greater holding strength), and the assembly can be rolled with the mouthpiece paper to hold the capacitive chip (CC tag) in place.

[0085] Such an assembly has the advantage of being integrated into current manufacturing processes for cigarettes or e-cigarette tobacco sticks.

[0086] Alternatively, the back electrode can be incorporated into either a hollow acetate tube, a cellulose acetate mouthpiece, or into a polymer membrane filter cooler (see below). A capacitive chip (i.e., any of the CC tags described throughout) can then be affixed to one of the three listed components. The position of the chip will then be maintained by paper wrapped around the tobacco stick.

[0087] Alternatively, and in addition to incorporating one electrode into the hollow acetate tube, the cellulose acetate mouthpiece, the polymer membrane filter cooler and the paper, a second electrode can be incorporated into the paper wrapped around the tobacco stick, the paper for the mouthpiece, respectively, where the second electrode preferably only partially covers the first electrode. In such a configuration, the first electrode is in contact with or close to the back electrode of the capacitive chip (CC tag), and the second electrode is in contact with or close to the top electrode of the capacitive chip, resulting in improved read sensitivity of the capacitive tag (CC tag).

[0088] Those skilled in the art will recognize that details of the above-described embodiments can be changed without departing from the scope of the invention as defined in the appended claims.

[0089] For example, CC tags and readers can operate using standard Industrial, Scientific and Medical (ISM) radio band frequencies (i.e., the frequency of the input RF signal). The frequency of operation can be, for example, 13.56 MHz (or between 10 MHz and 15 MHz). CC tags can operate at a different frequency (i.e., to avoid collision of data signals). Readers can, for example, scan at a different frequency.

[0090] Many combinations, modifications, or variations on the features of the above-described embodiments will be readily apparent to those skilled in the art and form a part of the invention. Any of the features specifically described in connection with one embodiment or example can be used in any other embodiment by making appropriate modifications.

Claims

1. 1. A capacitively coupled radio frequency identification (RFID) tag, comprising: a semiconductor substrate having a first planar surface and a second planar surface distal to the first planar surface; a metal pad formed on the first planar surface of the semiconductor substrate; a circuit formed on the semiconductor substrate and electrically connected to the metallic pad and the second planar surface of the semiconductor substrate, the circuit configured to respond to a radio frequency (RF) input signal by providing an encoded data signal by varying an impedance between the metallic pad and the second planar surface of the semiconductor substrate; and Equipped with the circuitry is further configured to detect the presence of one or more additional capacitively coupled RFID tags, and in response, to cease providing the data signal by reducing the impedance between the metallic pad and the second planar surface of the semiconductor substrate while the detected one or more additional capacitively coupled RFID tags change their own impedance. A capacitively coupled radio frequency identification (RFID) tag comprising:

2. 2. The capacitively coupled RFID tag of claim 1, The RF input signal is provided by an external reader; 1. A capacitively coupled RFID tag comprising:

3. 3. The capacitively coupled RFID tag according to claim 1, the circuitry is further configured to be powered by the RF input signal.

1. A capacitively coupled RFID tag comprising:

4. 4. The capacitively coupled RFID tag according to claim 1, the circuitry is further configured to decode a signal encoded within the RF input signal; the data signal is provided in response to the decoded signal; 1. A capacitively coupled RFID tag comprising:

5. 5. The capacitively coupled RFID tag according to claim 1, the circuit modulates the RF input signal by varying a frequency, an amplitude and / or a phase of the RF input signal; 1. A capacitively coupled RFID tag comprising:

6. 6. A capacitively coupled RFID tag according to claim 1, the circuit is formed on the second planar surface of the semiconductor substrate; 1. A capacitively coupled RFID tag comprising:

7. 7. A capacitively coupled RFID tag according to claim 1, the circuit is configured to vary the electrical impedance between the metallic pad and the second planar surface of the semiconductor substrate by applying a short between the metallic pad and the second planar surface of the semiconductor substrate.

1. A capacitively coupled RFID tag comprising:

8. 8. A capacitively coupled RFID tag according to claim 1, the distance between the outer surface of the metal pad and the second flat surface of the semiconductor substrate is 50 μm or less; 1. A capacitively coupled RFID tag comprising:

9. 2. The capacitively coupled RFID tag of claim 1, the circuit is configured to cease providing the data signal by applying a short between the metallic pad and the second planar surface of the semiconductor substrate.

1. A capacitively coupled RFID tag comprising:

10. 10. The capacitively coupled RFID tag of claim 1 or 9, the circuitry is configured to cease providing the data signal until one or more additional capacitively coupled RFID tags have provided their own data signals.

1. A capacitively coupled RFID tag comprising:

11. 11. A capacitively coupled RFID tag according to claim 1, 9 or 10, the circuitry is further configured to cease providing the data signal in accordance with an anti-collision protocol.

1. A capacitively coupled RFID tag comprising:

12. 12. The capacitively coupled RFID tag of claim 11, the anti-collision protocol is based on a predetermined sequence of responses, negotiated responses between the one or more capacitively coupled RFID tags, or communication between the one or more capacitively coupled RFID tags according to a random number generator; 1. A capacitively coupled RFID tag comprising:

13. 13. A capacitively coupled RFID tag according to any one of claims 1 to 12, the first planar surface is parallel to the second planar surface; 1. A capacitively coupled RFID tag comprising:

14. An article having embedded therein the capacitively coupled RFID tag according to any one of claims 1 to 13.

15. 15. The article of claim 14, a surface of the article is parallel to the first planar surface of the capacitively coupled RFID tag; An article characterized by:

16. 16. The article of claim 14 or 15, The object made of paper or made of plastic material is a banknote, a passport, an ID card, a tax stamp and / or a legal document. An article characterized by:

17. 1. A method for communicating with a plurality of capacitively coupled RFID tags, comprising: applying a radio frequency (RF) input signal to the plurality of capacitively coupled RFID tags by a reader comprising an RF signal generator and a decoder configured to decode a data signal; responding to the applied RF input signal by a capacitively coupled RFID tag of the plurality of capacitively coupled RFID tags by altering an impedance between a metallic pad of the capacitively coupled RFID tag and a flat surface, thereby encoding a data signal; detecting, by the reader, a variation in the RF input signal caused by the varying impedance of the one of the plurality of capacitively coupled RFID tags, the variation encoding the data signal; decoding, by the reader, the data signal from the variations in the RF input signal; Including, a non-responding capacitively coupled RFID tag of the plurality of capacitively coupled RFID tags decreases in impedance while the one capacitively coupled RFID tag changes the impedance of the one capacitively coupled RFID tag; A method comprising:

18. 20. The method of claim 17, one or more of the capacitively coupled RFID tags each operate at a different frequency; A method comprising:

19. 19. The method of claim 17 or 18, The plurality of capacitively coupled RFID tags are stacked one above the other; A method comprising:

20. 20. The method according to any one of claims 17 to 19, comprising: at least some of the plurality of capacitively coupled RFID tags are oriented in different directions; A method comprising:

21. 21. The method according to any one of claims 17 to 20, comprising: after the step of responding to the applied RF input signal; reducing the impedance of the one capacitively coupled RFID tag of the plurality of capacitively coupled RFID tags; changing the impedance of another non-responding capacitively coupled RFID tag of the plurality of capacitively coupled RFID tags; The method further comprising:

22. One or more capacitively coupled RFID tags according to any one of claims 1 to 16; a reader comprising an RF signal generator and a decoder configured to decode a data signal; A system comprising:

Images