Medication tracking system and method using hybrid isolated magnetic dipole probe

Abstract

A system and method for tracking medical articles located in a container includes a hybrid isolated magnetic dipole (“IMD”) probe that provides an activating EM energy RF field having a magnetic near field at least as great as the electric near field, both of which cover the entire interior of the container. The probe comprises a main element having capacitive coupling across at least one slot and spacing above a ground plane to thereby form an isolated electric field and an equally strong or stronger magnetic field that fills the interior of the container to activate RFID tags therein. A dual system is provided for larger containers. A dynamic impedance tuning system controls the probe impedance for increased efficiency in transferring power to the interior of the container. Beam steering is provided with the IMD probe.

Claims

1. A tracking system for tracking medical articles stored in an interior volume of a container, the interior volume of the container having a size selected to receive a plurality of medical articles each of which has a wireless identification device associated therewith that has individual identification data, and each wireless identification device configured to respond with identification data upon receiving activation energy, the interior volume of the container having a resonant frequency that is different from a frequency of operation of the wireless identification device, the system comprising: electromagnetic (“EM”) shielding located about the interior volume of the container configured to shield the interior volume of the container from the passage of EM energy both into and out of the interior volume, whereby the interior volume is isolated to keep activating radio frequency (“RF”) energy within the container so that radio frequency identification (“RFID”) tags located outside the container are not activated and read; an EM energy conducting injection probe located within the EM shielding, the injection probe located and configured to inject activation RF energy into the interior volume having an energy pattern directed to fill the interior volume of the container with an EM field, wherein the injection probe comprises a main conductive element having capacitive coupling across at least one slot of the main conductive element thereby forming an isolated electric field that fills the interior volume of the container, and wherein the main conductive element is spaced apart from a ground plane by a selected distance thereby forming a robust magnetic field that is orthogonal to the electric field and that also fills the interior volume of the container; a parasitic element located at a selected position in relation to the main conductive element of the injection probe, the parasitic element being configured to control the energy pattern of the main conductive element in the interior volume of the container; a receiving antenna located within the EM shielding at a position to receive identification data response signals from activated wireless identification devices located within the interior volume, the receiving antenna providing the received identification data response signals; a signal source producing activation radio frequency (“RF”) energy having a frequency that is different from the resonant frequency of the interior volume of the container, and coupled to the injection probe; and a processor connected with the signal source, the processor being programmed to control the signal source to deliver the activation RF energy to the injection probe for injecting into the interior volume of the container to activate identification devices in the interior volume, the processor further being programmed to stop the signal source from delivering RF energy to the injection probe to allow the receiving antenna to receive identification signals from activated identification devices in the interior volume, and further being programmed to receive the identification data response signals from the receiving antenna.

2. The medical article tracking system of claim 1 wherein the injection probe comprises a hybrid isolated magnetic dipole device in which the electric field and the magnetic field are circularly polarized.

3. The medical article tracking system of claim 1 wherein the injection probe includes a controllable active tuning element connected with the parasitic element to alter the effect of the parasitic element on the main conductive element to controllably change the energy pattern.

4. The medical article tracking system of claim 1 further comprising a dual injection probe circuit in which a plurality of injection probes are co-located and positioned in relation to each other to provide multiple energy patterns into the interior volume.

5. The medical article tracking system of claim 1 further comprising an active tuned impedance matching circuit connected with the injection probe that controls impedance of the injection probe to more closely match the impedance of the interior volume of the container whereby increased efficiency in electromagnetic energy transfer into the interior volume of the container results.

6. A method for tracking medical articles stored in the interior volume of a container, the interior volume of the container having a size selected to receive a plurality of medical articles each of which has a wireless identification device associated therewith that has individual identification data, and each wireless identification device configured to respond with identification data upon receiving activation energy, the interior volume of the container having a resonant frequency that is different from a frequency of operation of the wireless identification device, the method comprising: shielding the interior volume of the container from the passage of electromagnetic (“EM”) energy both into and out of the interior volume, whereby the interior volume is isolated to keep activating radio frequency (“RF”) energy within the container so that radio frequency identification (“RFID”) tags located outside the container are not activated and read; injecting activating RF energy into the interior volume in an energy pattern with an injection probe located within the EM shielding to fill the interior volume with an EM field, wherein the injection probe that comprises a main conductive element having capacitive coupling across at least one slot of the main conductive element thereby forming an isolated electric field that fills the interior volume of the container, and wherein the main conductive element is spaced apart from a ground plane by a selected distance thereby forming a robust magnetic field that is orthogonal to the electric field and that also fills the interior volume of the container; controlling the energy pattern in the interior volume with a parasitic element located at a selected position in relation to the main conductive element of the injection probe; delivering activating RF energy to the injection probe from a signal source, the activating RF energy having a frequency that is different from the resonant frequency of the interior volume of the container; receiving within the EM shielding identification data response signals from activated wireless identification devices located within the interior volume, the receiving antenna providing the received identification data response signals; and controlling the signal source to deliver the activating energy to the injection probe for injection into the interior volume, and controlling the signal source to stop delivering activating energy to the injection probe so that the injection probe may then receive responsive identification signals from activated identification devices, and receiving the identification data response signals from the receiving antenna.

7. The method of claim 6 wherein the step of injecting activating RF energy into the interior volume in the energy pattern with the injection probe comprises using an injection probe that comprises a hybrid isolated magnetic dipole device in which the electric field and the magnetic field are circularly polarized.

8. The method of claim 6 wherein the step of injecting activating RF energy into the interior volume in the energy pattern with the injection probe comprises using an injection probe that comprises a controllable active tuning element connected with the parasitic element to alter the effect of the parasitic element on the main conductive element to controllably change the energy pattern.

9. The method of claim 6 wherein the step of injecting activating RF energy into the interior volume in an energy pattern with an injection probe comprises using an injection probe that comprises a dual injection probe circuit in which a plurality of injection probes are co-located and positioned in relation to each other to provide multiple radiation patterns into the interior volume.

10. The method of claim 6 wherein the step of injecting activating RF energy into the interior volume in the energy pattern with the injection probe comprises using an injection probe having an active tuned impedance matching circuit that is configured to control impedance of the injection probe to more closely match the impedance of the interior volume of the container whereby increased efficiency in electromagnetic energy transfer into the interior volume of the container results.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a view of an automated dispensing cabinet (“ADC”) having multiple drawers in which articles are stored, the ADC having an article tracking system and a built-in computer configured for tracking the stored articles by processing data regarding articles put into the ADC and removed from the ADC, and communicating over one or more networks;

(2) FIG. 2 is a view of a 2.3 ft.sup.3 refrigerated cabinet in which medical articles are stored, and tracked, the cabinet in this case having a keypad and a display on the front door for interfacing with the programming of a processor in the cabinet;

(3) FIG. 3 is a view of a medication vial having a commonly-used RFID “flag tag” attached thereto, the flag tag in this diagram has a relatively large size that makes the vial bulky and can interfere with the handling of articles and storing the articles in a container;

(4) FIG. 4 is a view of the same medication vial of FIG. 3 but in this figure, a compact RFID flag tag is attached, the compact flag tag being much smaller than that of the previous figure due to the smaller size of the RF energy coupling device used in the RFID tag mounted thereon;

(5) FIG. 5 is a schematic block diagram of an RFID tracking system comprising an RFID reader positioned for scanning the interior of an article storage container, and having two separate RF energy conducting devices acting in one mode as RF probes for injecting activating RF energy into the container, and operating in a second mode as RF probes for receiving the RF responses of the activated RFID tags attached to articles stored in the container, the RF probes connected to conduct the RFID tag responses through a receiver to extract data and then to the processor of the RFID reader for further processing; the processor of the reader also programmed for frequency control over the signal generator for providing frequency hopping and timing control of the activating RF energy injected into the storage container by the RF probes;

(6) FIG. 6 is a perspective view of a larger refrigerated cabinet, in this case a 12 ft.sup.3 cabinet, with the front door open showing an embodiment of the placement of multiple RF probes in the cabinet for tracking medical articles put into, stored, and taken out of or removed from the cabinet;

(7) FIG. 7 is a top view of a hybrid isolated magnetic dipole (“IMD”) probe used for injecting activating RF energy into a container to activate RFID tags stored therein to respond with their individual identification data, the hybrid IMD probe having a single main element conductor located parallel to and distanced away from a circuit board with at least one slot in the single conductor for capacitive coupling that establishes a robust, but isolated, electric field in a container, and the spacing of the single main element above the circuit board to also establish a robust magnetic field in a container, a dynamic impedance matching device is shown located next to the main element and connected thereto for matching the impedance of the main element to the impedance of the container, and two parasitic elements;

(8) FIG. 8 is a perspective view of the hybrid IMD probe of FIG. 7 depicting the electric near field and the magnetic near field created by the probe, further showing the relative locations of the parasitic elements in relation to the main conducting element of the probe, wherein the parasitic element located beside the main element functions to steer the radiation pattern of the probe,

(9) FIG. 9 is a perspective view of a hybrid IMD probe having two parasitic elements each with an active tuning element and a third active tuning element under the main conductive element of the probe, wherein the first and second parasitic elements and all three active tuning elements are usable to control the energy pattern, or beam, of the main IMD element in the internal storage area of the storage container;

(10) FIG. 10 is a perspective view of a hybrid IMD probe similar to that of FIGS. 7 and 8 but lacking a parasitic element under the main conducting slotted element of the probe;

(11) FIG. 11 is a top view of a dual hybrid IMD probe circuit board with two hybrid IMD probes located at ninety degrees from each other, to establish eight separate and selectable radiation patterns or beams for providing activating RF energy to a container to activate RFID tags locate on articles in the container;

(12) FIG. 12 is another embodiment of a hybrid IMD device having the same main conductive element as the IMD devices above, but being mounted orthogonally to the circuit board;

(13) FIG. 13 is a perspective view of another embodiment of a hybrid IMD probe in which the main conducting element has two slots for capacitive coupling, and also showing a parasitic element with an associated active tuning element for providing selectable beams from the probe;

(14) FIG. 14 is a block diagram of the control over a hybrid IMD probe including its parasitic elements in injecting RF activating energy into a cavity or container to activate RFID tags in the container;

(15) FIG. 15 is a perspective view of a code tray showing a single level of various medical articles, each of which has an attached RFID tag, and showing a paper with an expiration date printed thereon indicating the earliest date of expiration when one or more of the stored medical articles in the tray expires, the tray being sealed with transparent plastic material; and

(16) FIG. 16 is a system for reading the RFID tags of the medical articles in the tray of the FIG. 15 comprising a box which provides electromagnetic shielding around the tray, and an RFID reader as well as a hybrid IMD probe for activating and reading RFID tags that are within the tray.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(17) Referring now in more detail to the exemplary drawings for purposes of illustrating embodiments of the invention, wherein like reference numerals designate corresponding or like elements among the several views, there is shown in FIG. 1 a representative medical dispensing cabinet 40 also known as an automated dispensing cabinet (“ADC”) 40. The ADC comprises a plurality of movable drawers 42. In this embodiment, there are five drawers that slide outwardly from the cabinet to provide access to the contents of the drawers. Each drawer may be thought of as a container having an interior volume in which medical articles may be stored. The cabinet also comprises an integral computer 44 that may be used to control access to the drawers and to generate data concerning access to and contents of the drawers, and to communicate with other systems. In this embodiment, the computer generates data concerning the number and type of items in the drawers, the names of the patients for whom they have been prescribed, the prescribed medications and their prescribed administration dates and times, as well as other information.

(18) In an embodiment, the ADC 40 comprises an RFID tracking system that tracks the contents of the drawers by activating RFID tags attached to the contents. The computer 44 may receive unique identification numbers from the RFID tags attached to the stored items and pass those identification numbers to an inventory control computer that has access to a database for matching the identification numbers to item descriptions, or perform those steps itself. The ADC of FIG. 1 also includes a user interface comprising a display 46, a typing keyboard 48, and a keypad 50. In another embodiment, the computer 44 contains a database and is capable of displaying the name of the medical article, the dose, the patient name for which it was prepared, and other data/information on the display and may accept commands from the user interface.

(19) As used in regard to the embodiments herein, “tag” is meant to refer to an RFID transponder. Such tags typically have a coupling element, such as an antenna, and an electronic microchip, also referred to as an integrated circuit (“IC”). The IC includes data storage, also referred to as memory.

(20) A cabinet exemplified by the ADC 40 of FIG. 1 may be located at a nursing station on a particular floor of a health care institution and may contain prescriptions for the patients of that floor. As prescriptions are prepared for the patients of that floor, they are delivered and placed into the cabinet 40. They are logged into the integral computer 44, which may notify the pharmacy of their receipt at the cabinet. A drawer 42 may also contain non-prescription medical supplies or items for dispensing to the patients as determined by the nursing staff or physicians. At the appropriate time, a nurse would access the drawer in which the medical items are stored through the use of the computer 44, remove a particular patient's prescriptions and any needed non-prescription items, and then close the drawer so that it is secured. In order to access the cabinet, the nurse may need to provide various information and may need a secure access code. The drawers 42 may be locked or unlocked as conditions require.

(21) In another embodiment, the drawers may be unlocked and accessible at any time by any one as desired. In another embodiment, one or more drawers may contain controlled substances, such as narcotics, and must be locked. In a further embodiment, all drawers, or no drawers, or only select drawers may be refrigerated.

(22) The computer 44 in some cases may be in communication with other facilities of the institution. For example, the computer 44 may notify the pharmacy of the health care institution that a patient's prescription has been removed from the cabinet 40 for administration at a particular day and time. The computer may also notify the finance department of the health care institution, and/or other entities, of the removal of prescriptions and other medical items for administration to a particular patient. This medication may then be applied to the patient's account. Further, the computer 44 may communicate to the institution's administration department for the purpose of updating a patient's Medication Administration Record (MAR), or e-MAR. The computer 44 of the medication cabinet 40 may be wirelessly connected to other computers of the health care institution or may have a wired connection. The cabinet may be mounted on wheels and may be moved about as needed or may be stationary.

(23) Although not shown, each of the five drawers of the ADC 40 contains a door, or drawer, sensor that detects when the respective drawer is opened. A door-open signal is generated and received by the integral computer 44 of the ADC. The signal is stored in a database along with the time of receipt for possible future reference. The same sensor or a different sensor may detect when the drawer is closed and generates a door-closed signal.

(24) FIG. 2 presents a different type of cabinet container 60. In this embodiment, the cabinet is a refrigerator having a small size, such as 2.3 cubic ft (ft.sup.3). In this embodiment, the front door 62 includes a keypad 64 and a display 66, as well as a handle to control whether the door is open or closed. The lower section 68 includes a processor, the RFID electronics, as well as communication electronics, power control, and any additional processors that may be needed. Although this embodiment shows a small refrigerator having a display and keypad, they are not necessary to the invention. The refrigerator 60 may have no user interface and the RFID tracking system of the refrigerator may automatically track the contents of the refrigerator and automatically communicate the results to a remote computer, or smartphone, or other device.

(25) FIGS. 3 and 4 present views of different RFID “flag-tags” 72 and 73 in use today. Both are attached to medical vials 70 that have the same size. The medical vial in both figures also have the same label 71 attached to the vial, on which is written various information about the contents of the vial, such as the name of the drug in the vial, the dose, the quantity, the expiration date, the manufacturer, the prescribing physician, and possibly more information or less information. The “flag tags” of FIGS. 3 and 4 are given this name because they include a length of paper 74 and 75 respectively or a “flag” portion upon which an RFID tag 76 and 77 respectively is mounted, and a mounting portion comprising a length of a clear attachment strip 78 and 79, having a clear adhesive, that is placed over the vial's label 71 to attach the flag tag to the vial 70. The mounting portion comprising the attachment strip and adhesive may be a tape material and are clear so that any information written on the label 71 of the vial 70 can be read through the mounting portion even though the respective flag tag is attached.

(26) In FIG. 3, the RFID flag-tag 72 is a typical size in use today as discussed previously, which is relatively large. The reason for the large size of the flag-tag is so that it can mount an RFID tag 76 that has a large coupling element 81 or antenna. The coupling element must be large enough to receive and collect an operational amount of activation RF energy to activate the RFID integrated circuit 82 of the RFID tag 80. Such large RFID tags are used on medical articles that are to be stored in containers having RFID tracking systems that do not provide a robust RF energy activation field. This field may also be referred to herein as an interrogation field or a reading field. Thus the coupling element 81 for RFID tags used in an environment such as this must be larger to collect more RF energy to activate the RFID tag 76.

(27) On the other hand, the RFID flag-tag 73 of FIG. 4 is much smaller than that of FIG. 3. This is due to the coupling element 83 or antenna of the RFID tag 77 of FIG. 4 being much smaller. The integrated circuit 84 of the RFID tag of FIG. 4 is approximately the same size as the integrated circuit 82 of the RFID tag 80 of FIG. 3. With an RFID tag 77 of the type of FIG. 4, a much stronger RF activating energy field must surround the RFID tag to activate it. RFID tracking systems that are designed with more efficient energy transfer, such as provided by the present invention, can successfully operate with the smaller sized RFID tags as shown in FIG. 4 and still produce a one-hundred percent read rate (also referred to as “interrogation rate,” “activation rate,” “detection rate,” and possibly other names). The advantage of using the smaller tags of FIG. 4 is that they take less room in a container, do not visibly obscure the existence of other medical articles, so not interfere with each other, and are easier to handle.

(28) FIG. 5 provides an RFID tracking system 130 in accordance with aspects of the invention in which an RFID reader 132 provides activating RF energy with a signal generator 92 to two RF energy conduction devices 134 and 136 that both operate in one mode as RF energy injection probes that provide activating RF energy to a container 96 interior 98. This activating energy activates RFID tags in the interior of the container which then respond with RF identification data. In this embodiment, the same EM energy conduction devices 134 and 136 also operate in a second mode as receiving probes that receive the responses of the activated RFID tags that are present in the container and that have been activated by the activating RF energy. The receiving probes 134 and 136 communicate those responses 102 to the RFID reader's receiver 106. The receiver is shown broken in this figure for the purpose of clarity in the figure. In this embodiment, it is a single receiver that extracts the identification data from the RF response signals of the activated RFID tags in the interior 98 of the container 96 and communicates that identification data to the processor 104. In another embodiment, multiple receivers may be used. Thus in this embodiment, the RF energy probes 134 and 136 operate wirelessly as both an energy injection probe and as a receiving probe.

(29) The system of FIG. 5 also comprises an RF energy conduction device switch 138 for selectively switching the RF probes 134 and 136 to either injection mode or receive mode as desired. Also, the processor 104 of the RFID reader 132 has been programmed for frequency control over the signal generator 92 for providing frequency hopping of the activating RF energy injected into the storage container 96.

(30) The term “probes” has been adopted for the energy transfer devices in this disclosure, as opposed to the word “antenna,” because the energy transfer device or devices are injecting and receiving EM energy from a cavity, which in this disclosure has been termed a “container.”

(31) FIG. 6 is a view of a much larger storage container 140, in this case a 12 ft.sup.3 refrigerated cabinet. Although not shown in the figure, medical articles may be stored in this refrigerator. Shelves have also been removed for clarity of the figure. A total of four RF probes 134, 136, 142, and 144 are mounted in the refrigerator interior 146 to scan the entire interior volume of the cabinet. FIG. 6 shows the particular placement of multiple probes in a 12 ft.sup.3 refrigerator; however, in another embodiment more or fewer such devices may be used depending on the circumstances and they may be placed in different locations. In this case, the four devices are mounted with two 134 and 136 on the back wall and two 142 and 144 on the left wall. The location of the RF energy conduction devices may also vary depending on particular circumstances of the container shape, size, and the type of RFID tags used.

(32) The performance of RFID tags will vary from one design to another. “Read performance” can be defined by a variety of RFID tag characteristics: read distance of a single tag in free space, probe polarization (linear or circular), sensitivity to adjacent tags, sensitivity to metal in close proximity, sensitivity to liquids in close proximity, sensitivity to detuning from packaging materials, location of the RFID tag in the enclosure, but also the orientation of the RFID tag, proximity of the tag to the enclosure walls and the drawer material (surfaces), among others. All of the above performance characteristics affect the statistical probability that a tag can be identified in an RF-enabled enclosure with multiple probes. In addition to variations in performance between differing tag designs, performance can also vary from one tag to another of the same design. Variations in the tag assembly process, the tag antenna material, and possibly the integrated circuit (“IC”) characteristics can result in performance variation within a group of one tag type/design.

(33) What has been needed, but not available, is an RF energy injection probe that can overcome the above sensitivities and performance-degrading conditions so that all RFID tags in the interior of a container are activated. A device satisfying this need has been found to be a hybrid isolated magnetic dipole (“IMD”) probe. The hybrid IMD probe has been found to provide superior efficiency, isolation, and selectivity characteristics and has a relatively small size due to the configuration of the elements used. The hybrid IMD probe excites a magnetic dipole mode from a metal structure in such a fashion as to minimize the fringing fields typically generated between a probe element and an adjacent ground plane. A current is induced on the probe structure and a strong electric field is generated on the structure in the plane of the IMD element instead of a strong fringing field to the ground plane. By minimizing the coupled fields to the ground plane, with the circuit board of a wireless device taking the place of the ground plane, improved efficiency and isolation can be obtained. Single and multi-resonant elements can be created to address a wide range of frequency bands.

(34) The hybrid IMD probe confines current flow on the probe main conductive element and thereby optimizes the isolation. Near-field emissions are controlled. Other probe designs have strong current flows radiating out onto their ground plane board and lose large amounts of energy resulting in lower probe efficiency. The hybrid IMD probe design provides a solution for accurately and repeatedly identifying RFID tags attached to both large and small medication form factors in small non-resonant RF-enabled enclosures. RFID tag interrogation performance in a non-resonant cavity can be improved by using the hybrid IMD probes disclosed here instead of electric probes or magnetic loops or half loops. The near-field magnetic properties along with high cross polarization characteristics of the hybrid IMD probe main element provide unique capabilities when the hybrid IMD probe is used as an energy injection probe in the cavity. The improvement from using hybrid IMD probes as injection probes in the non-resonant cavity compared to typical electric or magnetic probes is due to the ability of the hybrid IMD probe to act as a magnetic and electric field probe simultaneously as a result of the high cross polarization of the IMD main element.

(35) The hybrid IMD probe is formed by coupling one element to another in a manner that forms a capacitively-loaded inductive loop, setting up a magnetic dipole mode. This magnetic dipole mode provides a single resonance and forms a probe that is efficient and well isolated from the surrounding structure. This is, in effect, a self-resonant structure that is decoupled from the local environment.

(36) The hybrid IMD probe involves placing a conductor in close proximity to a slot or conductive regions of an IMD probe to create a reactive section capable of increasing the bandwidth of the IMD probe. The conductor can be capacitively coupled to the IMD probe or can be connected to a portion of the IMD probe. Lumped reactance in the form of capacitors and/or inductors can be incorporated into the probe structure, to both the driven element and/or the coupled element, to provide additional adjustment to the frequency response. Increases in both efficiency and bandwidth have been documented from this technique which more efficiently utilizes the volume that the probe occupies.

(37) A first type of hybrid IMD probe (Type 1) 160 as shown in the top view of FIG. 7 comprises a pair of conductors 162 and 164 placed in close proximity to each other with portions of each conductor positioned in parallel with each other. One conductor 162 is connected to a signal source 166 and a second conductor 164 is grounded 168 on one end. The overall structure of the main element 170 can be considered as a capacitively-loaded inductive loop. The capacitance is formed by the coupling between two parallel conductors 162 and 164 with the inductive loop formed by connecting the second element 164 to ground 168. The length of the overlap region between the two conductors along with the separation 172 between conductors is used to adjust the resonant frequency of the probe 160. A wider bandwidth can be obtained by increasing the separation between the conductors, with an increase in overlap region used to compensate for the frequency shift that results from the increased separation. This type of hybrid IMD probe requires a ground plane 174 for operation. With a ground plane 174 coupled to the IMD probe 170, this hybrid IMD probe can be considered a half-loop radiator, providing a strong magnetic field component in the near-field of the probe as well as a strong electric field.

(38) Also shown in FIG. 7 is an active impedance matching circuit 188 in block form. The main element 170 of the IMD probe 160 is connected with the matching circuit to vary the impedance of the IMD probe to a value as close to the impedance of the container with which it is associated as possible so that energy is efficiently transferred between the two. Such impedance matching circuits are known in the art. See U.S. Pat. No. 8,384,545 to Hussain et al., incorporated herein by reference, for a description of such a circuit usable here.

(39) FIG. 8 shows a perspective view of the IMD probe 160 of FIG. 7 and further shows the magnetic field “H” 180 and the electric field “E” 182 created by the IMD probe. It will be noted that the electric field “E” is in the X plane while the magnetic field “H” is in the orthogonal Y plane. Both fields are robust and fill the entire interior of a container 60 such as that shown in FIG. 2.

(40) An advantage of this hybrid IMD type of probe structure is the method in which the probe is fed or excited. This leaves great flexibility for reduced-space integration. The probe size reduction is obtained by the capacitive loading that is equivalent to using a low loss, high dielectric constant material. At resonance a cylindrical current going back and forth around the loop is formed. This generates a magnetic field “H” 180 along the axis of the loop which is the main mechanism of radiation. The electrical field “E” 182 remains highly confined between the two elements 162 and 164. This reduces the interaction with surrounding metallic objects and obtains high isolation.

(41) In accordance with one aspect of the invention, the hybrid IMD probe 160 of FIGS. 7 and 8 provides high energy efficiency. The hybrid IMD probe comprises a capacitively-coupled inductive loop 170 where multiple components of a part of the loop are capacitively coupled together to create a robust electric field and the inductive coupling of the components to the ground plane create an equally robust magnetic field. FIG. 8 provides a perspective view of an IMD main element 170 situated above a ground plane 174. The ground plane 174 may include an impedance matching circuit 188 incorporated therein. The main element of the probe 170 consists of a slot region 172 and prong type feed and ground legs 184. A current is induced around the U-shaped probe structure 170 through a feed port and ground of the wireless device. The current is induced in order to generate a strong electric field in the slot region, in the plane of the IMD element 170 instead of a strong fringing field to the ground plane 174 below it. This minimizes the coupled fields to the ground plane 174. With a circuit board of a wireless device acting as the ground plane, an improved efficiency and isolation may be obtained. Different configurations of these resonant elements may be made in order to address a wide range of frequency bands.

(42) The length of the IMD element 170 may be modified to be longer or shorter dependent on the frequency desired. For instance, longer IMD elements 170 show improved lower frequency ranges. In addition the center slot capacitive region 172 may be wide or narrow. In addition multiple slot regions may be formed, as is provided in FIG. 13. The height of the IMD element 170 above the ground plane 174 also affects the frequency range functionality of the probe. By displacing the portions of the structure in three dimensions, the IMD element can be optimized at various frequency regions. Lower frequencies will be more efficient when implemented with increased height, such as 6 mm, while higher frequencies will be more efficient with lower heights, such as 4 mm. As well, the height above the ground plane for optimal efficiency varies as probe operation varies from 1800 MHz to 2200 MHz. Discrete steps in height are applicable, as well as variable and continuous increases or decreases in element height as a function of element length. For further details on modifying an IMD probe, refer to U.S. Pat. No. 7,777,686, incorporated herein by reference.

(43) The embodiment of a hybrid IMD probe shown in FIGS. 7 and 8 comprises an isolated main probe element 170, a first parasitic element 210, and a first active tuning element 212. The first parasitic element 210 and its associated first active tuning element 212 are positioned to one side of the main probe element. In one embodiment, the first active tuning element is adapted to provide a split resonant frequency characteristic associated with the probe 170. The first active tuning element may be adapted to rotate the radiation pattern associated with the IMD probe 160. This rotation may be effected by controlling the current flow through the parasitic element 210. In one embodiment, the first parasitic element 210 is positioned on a substrate 174. This configuration may become particularly important in applications where space is the critical constraint. In one embodiment, the parasitic element is positioned at a predetermined angle with respect to the main probe element 170. For example, the first parasitic element 210 may be positioned parallel to the main probe element 170, or it may be positioned perpendicular to the main probe element. The parasitic element may further comprise multiple parasitic sections.

(44) In one embodiment of the present invention, the first active tuning element 212 comprises at least one of the following: voltage controlled tunable capacitors, voltage controlled tunable phase shifters, FETs, and switches.

(45) In another embodiment of the present invention, the probe 160 further comprises a plurality of parasitic elements, and a plurality of active tuning elements, as is shown in FIGS. 7 and 8. In this embodiment, the probe 160 includes a first parasitic element 210 and a first active tuning element 212 associated with the first parasitic element, wherein the first parasitic element and the first active element 212 are positioned to one side of the main probe element 170. The embodiment also includes a second parasitic element 232 and a second active tuning element 234 associated with the second parasitic element. The second parasitic element and the second active tuning element are positioned below the main probe element 170. In this case, the second parasitic and active tuning elements are used to tune the frequency characteristic of the probe 160, and in another embodiment, the first parasitic and active tuning elements are used to provide beam steering capability for the probe.

(46) In one embodiment of the present invention, the radiation pattern associated with the probe is rotated in accordance with the first parasitic and active tuning elements. In some embodiments, this rotation may be ninety degrees.

(47) In another embodiment of the present invention shown in FIG. 9, the probe 230 further includes a third active tuning element 240 associated with the main probe element 192. This third active tuning element is adapted to tune the frequency characteristics associated with the probe.

(48) Referring now to FIG. 10, a different embodiment of a hybrid IMD probe 244 is shown. In this embodiment, the hybrid IMD probe 244 includes a first parasitic element 210 and associated first active tuning element 212 but does not include the second parasitic element located under the main element 170 as shown in FIGS. 7, 8, and 9. The embodiment therefore has fewer parts, less programming in that a second active tuning element does not need to be controlled, nor is there a third active tuning element that needs to be controlled (see FIG. 9 for the first, second, and third active tuning elements 212, 232, and 240).

(49) Referring now to FIG. 11, a further embodiment is shown having dual hybrid IMD probes. In particular, two hybrid IMD probes 246 and 248 are located on the same circuit board 249. Each probe 246 and 248 includes a main conducting element 280 and 282 respectively, and a first parasitic element 284 and 286 with an active tuning element associated with both 288 and 290. It will be noted that these two co-located dual hybrid IMD probes are oriented so that they are ninety degrees from each other in this embodiment. The first parasitic element of each permits four separate radiation patterns or “beams” for each probe resulting in a total of eight radiation patterns 249 for the entire circuit board 249 of dual hybrid IMD probes. Because the two probes are oriented at a particular angle to each other, the eight radiation patterns do not overlap in this embodiment. However, in other embodiments, overlap may be desired and different orientations of the probes in relation to each other may be implemented. This embodiment is particularly applicable for use in larger containers, but may also be used in smaller containers as well.

(50) FIG. 12 presents a perspective view of a hybrid IMD probe 300 in which the main conducting element 302 is mounted orthogonally on the circuit board 304. Similar performance can be obtained with this configuration as described above.

(51) A second type of hybrid IMD probe 190 is shown in FIG. 13 and provides two resonances for use in dual frequency band or multi-band applications. This second type of hybrid IMD structure is composed of a planar main element 192 positioned above a ground plane 194. Two slots 196 and 198 are formed in one section of the planar conductor. The probe is excited in such a way that there are strong electric fields in the slot regions, with the slots being dimensioned to resonate at two different frequencies. The strong electric fields in the slot regions is a result of opposing currents flowing on two portions of a planar conductor that are parallel to one another. The two opposing currents on the conductor provide a magnetic field distribution similar to the fields formed by a half loop element above a ground plane, as is shown in FIG. 8. The result is a probe that has reduced fringing electric fields between the probe conductor and the ground plane, and a magnetic field distribution that is similar to a loop. A good mix of electric and magnetic fields are present in the near-field. The planar conductor 200 forming the probe is typically positioned above and in parallel to a ground plane 194. A conductor forming a feed leg 202 and a conductor forming a ground leg 204 are positioned orthogonal to the plane of the planar conductor. In this configuration the IMD probe forms a volume encompassed by the planar conductor and the ground plane, which determines the frequency bandwidth.

(52) The parasitic element 206 and its associated active tuning element 208 result in multiple selectable radiation patterns or beams from the probe.

(53) The planar slot configuration shown in the conductor shown in FIG. 13 provides equivalent radiated field performance as a pair of capacitive loops, one large loop and one small loop. The fields are equivalent due to the orientation of the slot configuration and the direction of current flow on individual portions or conductive sides of the slot.

(54) Unlike other probes, such as the Planar Inverted F-Style Antenna (PIFA), the hybrid IMD probe 190 has an underlying advantage in that its properties depend mainly on the probe structure itself and not the surrounding area. In the hybrid IMD probe 190, the electrical currents are strongly localized to the probe region and do not propagate on the ground 194. This is an important feature as any probe employed for identifying RFID tags in metallized or shielded enclosures will by definition be in close proximity to large metal areas.

(55) For further details on selecting or “steering” probe radiation patterns or beams, refer to U.S. Pat. No. 7,911,402, which is incorporated herein by reference.

(56) Referring now to FIG. 14, In regard to the hybrid probes shown and described above having a parasitic element that provides for beam steering or radiation pattern selection, a main processor 252 signals the IMD parasitic controller 254 to select a particular beam of the probe 256 to activate. The parasitic controller then controls the various parasitic elements 258 and active tuning elements associated therewith to set the particular beam with which the probe will operate. The main processor 252 then controls the RFID reader 260 to provide activating RF energy to the main IMD element 262 through a signal generator 264. The probe 256 operates to inject activating RF energy to activate all RFID tags in the beam selected. The probe 256 is then controlled, in one embodiment, to receive the responsive signals from activated RFID tags in the container of interest, and forward the received responsive signals 266 to the RFID reader 260. Also shown is an active impedance matching control 268 to increase energy transfer between the probe 256 and a container.

(57) In one case, the beam steering may be dynamic, in that the processor has the hybrid IMD probe change beams periodically. In another case, the beam selected for use by the probe is selected based on the location of the probe in the container, and that beam is fixed in that the probe only operates on that beam, or mode, for the entire life of the container. In one embodiment, the probe had four “beams” or “modes” at which the probe could be set.

(58) Referring now to FIG. 15, another type of container or storage system is commonly known as a tray or code tray, and may have other names. The code is typically used to identify the medical purpose of the tray, such as a “code blue” tray to resuscitate a person undergoing cardiac arrest. Such a tray may be formed of non-metallic material such as composites or plastics. The tray holds all of the medications, tools, and equipment that are expected to be required to complete a medical procedure or to handle a particular medical event.

(59) A tray is typically laid out and displayed in an easily recognizable fashion. Color may be used also to assist in managing the inventory of the tray. This allows an assistant to retrieve the correct medication or instrument without delay. In the event that a surgeon is looking for the optimum tool or medication, a quick glance at the surgical tray will allow the identification of all available tools at his or her disposal. Labels are often placed on the tray also that specify what is in the pockets of the tray.

(60) An example of such a medical “tray” is shown in FIG. 15. The tray 320 is a single layer and includes various pharmaceuticals 322 and other medical articles, such as pre-loaded syringes 324 (epinephrine syringe, lidocaine syringe, and an atropine syringe). The entire tray is sealed with clear plastic wrap 326 and an inventory list 328 is contained just under the plastic seal so that it is visible and readable without breaking the seal. The Required Inventory list in this case identifies the name of the tray, such as “Childbirth Tray,” lists the contents of the tray, and includes other information such as the first expiration date of any of the articles contained in the tray. The Required Inventory list may also contain a plan layout of the tray showing which articles should be stored where. It may have multiple pages or only a single page.

(61) The tray 320 has been prepared by a pharmacist at the pharmacy because it has prescription medications in it (oxycontin for example). The Required Inventory list may also include brand names as well as generic names, and National Drug Codes (“NDCs”) or Universal Product Codes (“UPCs”) as part of the inventory. State regulations typically allow a hospital or other facility to define the contents of its trays, and therefore they can be selected based on particular “community” standards and requirements. State regulations, typically require that the hospital have specific procedures to ensure accuracy of tray contents. Such procedures include inventory and restocking procedures, as well as detection of expired and recalled medical articles. In the example of FIG. 14, the tray is relatively small. However for other purposes, a tray can be much larger with many more medical articles. Some trays may include additional layers that may or may not include additional items not contained in the top layer.

(62) If the seal is broken, regardless of whether any of the contents were removed, an inventory will likely be required. Existing processes require that this be done manually. Each of the articles in the tray is examined to determine if it is expired or recalled, and is compared against the Required Inventory list to determine if it should be in the tray. The Required Inventory list is also referenced for checking that all required articles are in the tray and that extra articles are not in the tray. Once it has been restocked, the tray 320 is resealed 326 and may be placed on the floor again for medical use. Such examination and restocking can take significant amounts of time and if a pharmacist is required to perform some of the inventory process, that pharmacist will be unavailable to perform other duties. In such a manual procedure, mistakes can be made. Thus, a need has been identified to provide a more efficient and accurate system and method to restock such carts and trays.

(63) Crash carts and trays must be resupplied periodically to replace expired or recalled items, and if a cart or a tray was actually used, to replace consumed articles. As mentioned, such processes are typically performed manually at a significant cost in time. Missing key medical articles in a tray could be devastating in an emergency situation. Therefore accuracy in the resupply is mandatory. Often, trays that have articles that are just nearing expiration must be returned to the pharmacy for resupply in advance of expiration due to the time it takes to process the tray. Any recalled articles must also be removed and substitutions made. It is also possible that items foreign to the crash cart or tray have been added while they were in the field, and these foreign articles must be found and removed.

(64) Unfortunately, the above procedures tend to suffer from significant shortcomings. For instance, manual inspections can result in errors as can resupply. Creating records of what was done is also generally time consuming and error prone, all of which drive up the cost of creating and resupplying the carts and trays. There has therefore been recognized a need for improvement in managing such crash carts and trays.

(65) Furthermore, under the current system, the pharmacy is unable to create individualized carts for patients. For example, certain patients may be provided a patient-specific cocktail of drugs (this may be a mixed vial or a combination of drugs). Because these are non-standard drugs or drug combinations, a pharmacist has to double check a drug list or a prescription list when creating a cocktail drug or filling a personalized cart with medical items.

(66) FIG. 16 shows an embodiment of an inventory management system 340 according to aspects of the invention. An enclosure 342 is shown, which in this case creates an EM energy shielded cage in that all the walls and top and bottom are electrically shielded to isolate the enclosure by preventing (or significantly attenuating) EM from entering or escaping the enclosure. The enclosure is fitted with a reader 344 configured to interrogate RFID tags located within the enclosure. One or more hybrid IMD probes are locate within the enclosure 342 and are connected to the reader 344.

(67) The reader 344 is connected to a computer 346 through a connection 348. The connection 348 may be a wired connection, wireless connection, or any other suitable connection for data transfer. In one embodiment, the physical body of the computing system may be attached to the enclosure 342. The computing system 346 has a non-volatile memory 354 in which is stored at least one database (“db”) which may be a local database, or other. The non-volatile memory 354 comprises one or more computer readable media within the computer system 346 and may be located within the computer itself or external to the computer. The memory is shown here as being outside the computer only for clarity of illustration in the discussion and is not meant to limit the invention in any way. In another embodiment, part or all of the local database may be held on a server 360. The computing system 346 is also connected to the remote database 360 at which is located a first remote database 362 and a second remote database 364. As in the local computer, these remote databases may be stored on a memory that is internal to the server or that is external to the server. Further, the server 360 may be located nearby the local computer 346 or may be remote therefrom. By remote, it is meant that it may be in the same room, or in the same wing, or in the same facility, or may be in the cloud. Connection 366 to the server 360 may likewise be a wired connection, wireless connection, or any other suitable connection for data transfer.

(68) In one embodiment, the data held on the local database 352 may depend on the location/specialty/facility using computer system 346. For example, if the computer system 346 were stationed in an emergency room (“ER”), the local database 352 may hold only information or data regarding medical articles, medical containers, and other inventory most used in an ER. In one embodiment, the remote database 362 at the server 360 may serve as a main database and contain data for all medical articles, medical containers, and other inventory for all medical locations/facilities/specialties. The local database 352 may maintain a copy of the portion of data held on the remote database 362 that is most relevant to the computer system 346, but can access the remote database 362 when encountering medical items, medical containers, or other inventory for different facilities/specialties/locations.

(69) The enclosure 342 has an opening 370 through which a tray 372 may be slid into the enclosure. The tray is placed completely within the enclosure so that the front door 374 can be closed over the opening 370 to complete the Faraday cage of the enclosure 342. The tray includes a number of medical items 376 with each one having an RFID tag 378 attached. As discussed previously, each RFID tag has a stored different identification number comprising a few bytes with a check digit. The error codes are not stored in the tag memory. They are generated on the fly. Manufacturers guarantee that each serial number is used only once. Some RFID tags have more complex codes for identifying the RFID tag. In this case, the tray 372 also has an RFID tag 280 attached to its outer surface 382. The reader 344 will read those identification numbers from the tags, communicate them to the computer which will compare them against one or more databases either locally 352 or remotely through a server 362 and/or 364. The process of using the identification numbers of the tags is discussed below.

(70) Medical item information may include information such as name, lot code, date of manufacture, expiration date, dosage, weight, color, and an image of the medical article. In one embodiment, the identification (“ID”) data may be partially made of drug codes that identify the drugs. As an example and not by way of limitation, the identification data may use the National Drug Code (“NDC”) as part of its data allowing for easy identification of the attached medical item. Identification data may also have other identifying codes that establish the manufacturer, lot code, dosage, drug type, expiration date, etc.

(71) Shown in FIG. 16 is an enclosure 342 formed in accordance with aspects of the invention by which it is much smaller than an enclosure sized to be resonant at the operating frequency of RFID yet the EM field within the enclosure 342 is highly robust and effective at exciting and reading all RFID tags located therein due to the use of a hybrid IMD probe or probes. Because inventive aspects are incorporated, the enclosure is much smaller than other enclosures and is therefore highly desirable in areas where space is limited, such as a pharmacy in a healthcare facility. Although not shown, the front door 374 includes latching hardware to retain it in a closed when it is rotated upwards and put in use. A handle 384 assists in managing the configuration of the front door. The enclosure is formed of a metallic mesh or other EM shielding material to provide an EM shielded cage about trays that are slid within it for scanning and inventorying. The front door in this embodiment is also formed of an RF shielding material. An RFID reader 344 is shown in dashed lines which may also contain a hybrid IMD probe or probes, the electronics, and a battery 388 for the enclosure. The electronics include a processor, communications, wired and wireless connections, and a local power source. In another embodiment, an AC adapter may be included for using wall power. Communications ability over networks is provided.

(72) The approximate volume for a resonant enclosure at an RFID operating frequency of 900 MHz is 3 ft.×3 ft.×3 ft. for a total of 27 cubic feet. In one embodiment, the enclosure 342 had the dimensions of 2.25 ft. wide by 1.6 ft. long by 0.88 ft. high for an approximate volume of 3.15 cubic feet, and with the use of a hybrid IMD probe or probes, achieved equally effective electric and magnetic fields within the enclosure at exciting and reading all RFID tags located therein. The difference in sizes of the two enclosures makes one formed in accordance with the invention more attractive in many situations where space is limited.

(73) The above may also be combined with a frequency hopping arrangement and a Return Signal Sensitivity Indicator arrangement for increasing the likelihood of activating all RFID tags in a particular container. For further details on such arrangements, see U.S. Patent Application Publication No. 2014/0184391, application Ser. No. 14/142,749, now U.S. Pat. No. 9,349,030 which is incorporated herein by reference.

(74) The invention is intended to provide a read process that ensures the highest statistical probability of identifying all RFID tags contained in the RF-enabled enclosure.

(75) Although shown and described in the embodiment of a medical article tracking system and method, the invention can have application to other fields of tracking outside the medical field.

(76) A Faraday cage is mentioned; however, this device is also known as a Faraday shield and Faraday screen. In addition, other EM shielding is usable. Different EM shielding can produce the desired isolation of keeping activating RF energy within the container so that RFID tags located outside the container are not activated and read. Mistakenly reading RFID tags that are located outside the container can cause errors since the tracking system of the container will not be able to determine that the RFID tag is outside the container and will return a result showing that it is in the container.

(77) Although RFID tags are used herein as an embodiment, other data carriers that communicate through electromagnetic energy may also be usable.

(78) Unless the context requires otherwise, throughout the specification and claims that follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense, which is as “including, but not limited to.”

(79) Although RFID tags are used herein as an embodiment, other data carriers that communicate through electromagnetic energy may also be usable.

(80) Unless the context requires otherwise, throughout the specification and claims that follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense, which is as “including, but not limited to.”

(81) While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments and elements, but, to the contrary, is intended to cover various modifications, combinations of features, equivalent arrangements, and equivalent elements included within the spirit and scope of the appended claims.