Patent Application
20240148269
This disclosure relates generally to interrogation and detection systems for radio-frequency (RF) tags, and more particularly, interrogation, detection and inventory systems for radio-frequency (RF) tags for use within surgical sites.
It is often useful to determine whether objects associated with a surgery are present in a patient's body before completion of the surgery. Such objects may take a variety of forms. For example, the objects may take the form of instruments, for instance, scalpels, scissors, forceps, hemostats, and/or clamps. Also, for example, the objects may take the form of related accessories and/or disposable objects, for instance, surgical sponges, gauzes, and/or pads. Failure to locate an object before closing the patient may require additional surgery, and in some instances, may have unintended medical consequences.
Accordingly, there is a need for a technology that is capable of providing both presence detection and tagged surgical item/implement identification functionality in the medical setting, as well as inventory controls of the tagged items/implements. Specifically, detecting the presence of, identifying, and maintaining inventory of tagged surgical items and materials that are used during the execution of a medical procedure. Technologies exist that enable these functions both individually as well as in conjunction with each other, but the methods and packaging of the discrete solutions used are not ideal for the application. More specifically, the components attached or affixed to the items being tracked are either too large physically and present nuisances or obstacles in the execution of the procedure, or the detection and identification performance of the solution may degrade rapidly in the presence of variable and uncontrolled dielectric or conductive materials.
Accordingly, there are needs for improvements in presence detection, tagged item identification, and inventory functionality in the medical setting.
This disclosure relates to systems for detection of surgical objects and devices used in body cavities during surgery, specifically antennae to be inserted directly into a surgical site.
In accordance with aspects of the disclosure, an interrogation and detection system for detection of surgical implements within a patient's body is presented. The system includes an RFID tag configured to transmit a return signal when energized, a signal generator configured to generate an energizing signal for the RFID tag, and a coil antenna operably coupled to the signal generator, the antenna configured to receive a return signal transmitted by the RFID tag. The coil antenna includes a primary coil, a secondary coil, and a core configured to couple electromagnetic energy from the secondary coil to the primary coil. The core includes a non-magnetic insulating material. The secondary coil is configured to receive the return signal. The primary coil is configured to couple electromagnetic energy from the secondary coil. The RFID tag affixed to a surgical implement.
In an aspect of the present disclosure, a “turns ratio” between the primary coil and the secondary coil may be greater than or equal to 1:1. The “turns ratio” is a ratio between a first quantity of turns of the primary coil and a second quantity of turns of the secondary coil.
In another aspect of the present disclosure, the secondary coil may include a resonant frequency within 10% of an operating frequency of the return signal.
In yet another aspect of the present disclosure, the secondary coil may include an inductance greater than or equal to 2.5 uH.
In a further aspect of the present disclosure, the coil antenna may further include a first matching network electrically connected to the primary coil. The first matching network is configured to match an input impedance of the primary coil to an output impedance of the generator.
In yet a further aspect of the present disclosure, the coil antenna may further include a second matching network electrically connected to the secondary coil. The second matching network is configured to match an input impedance of the secondary coil to an output impedance of the primary coil.
In an aspect of the present disclosure, the primary coil may be a first planar coil.
In another aspect of the present disclosure, the secondary coil may be a second planar coil.
In yet another aspect of the present disclosure, the primary coil may include a first turn and a second turn.
In a further aspect of the present disclosure, the first turn of the primary coil and the second turn of the primary coil may be arranged in an offset manner in a vertical and a horizontal orientation.
In yet a further aspect of the present disclosure, the secondary coil may include a first turn and a second turn.
In an aspect of the present disclosure, the first turn of the primary coil and the second turn of the primary coil may be arranged in an offset manner in a vertical and a horizontal orientation.
In accordance with aspects of the disclosure, a coil antenna configured to receive a return signal transmitted by the RFID tag is presented. The coil antenna includes a primary coil, a secondary coil, and a core configured to couple electromagnetic energy from the secondary coil to the primary coil. The core includes a non-magnetic insulating material. The secondary coil is configured to receive the return signal. The primary coil is configured to couple electromagnetic energy from the secondary coil.
In another aspect of the present disclosure, the primary coil and the secondary coil may each be planar coils.
In yet another aspect of the present disclosure, the primary coil may include a conductor.
In a further aspect of the present disclosure, the conductor of the primary coil includes a conductor that may have a configuration including coaxial, planar, a “C” shaped transverse cross-sectional shape, and/or tube-shaped transverse cross-sectional shape.
In yet a further aspect of the present disclosure, a “turns ratio” between the primary coil and the secondary coil may be greater than or equal to 1:1. The “turns ratio” is a ratio between a first quantity of turns of the primary coil and a second quantity of turns of the secondary coil.
In an aspect of the present disclosure, the secondary coil may include a resonant frequency within 10% of an operating frequency of the return signal.
In accordance with aspects of the disclosure, a method for inventory control of tagged items is presented. The method includes transmitting an energizing signal by a coil antenna operably coupled to a signal generator, the coil antenna including a primary coil, a secondary coil, and a core configured to magnetically couple the secondary coil to the primary coil, the energizing signal configured to energize an RFID tag affixed to an item and configured to transmit a return signal when energized and receiving a return signal, by a primary coil of the coil antenna.
In yet a further aspect of the present disclosure, the method further may include detecting and/or identifying the item based on the return signal. The item may include a surgical implement.
In accordance with aspects of the disclosure, a coil configured to receive a return signal transmitted by an RFID tag, includes a first turn conductor and a second turn conductor electrically connected to the first turn conductor.
In an aspect, the first turn conductor may be located in parallel relation and an offset manner to the second turn conductor.
In an aspect of the present disclosure, the first turn conductor may include a first inner edge and a first outer edge. The second turn conductor may include a second inner edge and a second outer edge.
In another aspect of the present disclosure, the coil may be arranged in a circular, square, rectangular, or oblong configuration.
In yet another aspect of the present disclosure, the first turn conductor may overlap the second turn conductor of the staggered coil, where a substantial portion of the second turn conductor is not overlapped by the first turn conductor.
In accordance with aspects of the disclosure, coil antenna configured to receive a return signal transmitted by an RFID tag, includes a primary coil and a secondary coil. The secondary coil includes a first turn conductor and a second turn conductor electrically connected to the first turn conductor. The secondary coil is configured to receive the return signal. The primary coil is configured to couple electromagnetic energy from the secondary coil.
In a further aspect of the present disclosure, the coil antenna may further include a core configured to couple electromagnetic energy to and from the secondary coil to the primary coil The core includes a non-magnetic insulating material.
In yet a further aspect of the present disclosure, the first turn conductor may be located in parallel relation and an offset manner to the second turn conductor.
In yet a further aspect of the present disclosure, a “turns ratio” between the primary coil and the secondary coil may be greater than or equal to 1:1. The “turns ratio” is a ratio between a first quantity of turns of the primary coil and a second quantity of turns of the secondary coil.
In an aspect of the present disclosure, the secondary coil may include a resonant frequency within 10% of an operating frequency of the return signal.
In another aspect of the present disclosure, the secondary coil may include an inductance greater than or equal to 2.5 uH.
In yet another aspect of the present disclosure, the coil antenna may further include a first matching network electrically connected to the primary coil. The first matching network may be configured to match an input impedance of the primary coil to an output impedance of the signal generator.
In accordance with aspects of the disclosure, an interrogation and detection system for the detection of surgical implements within a patient's body is presented. The interrogation and detection system includes an RFID tag configured to transmit a return signal when energized, a signal generator configured to generate an energizing signal for the RFID tag, and a coil antenna operably coupled to the signal generator, the antenna configured to receive a return signal transmitted by the RFID tag. The RFID tag is affixed to a surgical implement within the patient's body. The coil antenna includes a primary coil and a secondary coil. The secondary coil includes a first turn conductor and a second turn conductor electrically connected to the first turn conductor. The first turn conductor may be located in parallel relation and an offset manner to the second turn conductor. The secondary coil is configured to receive the return signal. The primary coil is configured to couple electromagnetic energy from the secondary coil.
In a further aspect of the present disclosure, the secondary coil may be air-core coupled to the primary coil.
In yet a further aspect of the present disclosure, a “turns ratio” between the primary coil to the secondary coil may be greater than or equal to 1:1. The “turns ratio” is a ratio between a first quantity of turns of the primary coil and a second quantity of turns of the secondary coil.
In accordance with aspects of the disclosure, the secondary coil may include an inductance greater than or equal to 2.5 uH.
In an aspect of the present disclosure, the coil antenna may further include a first matching network electrically connected to the primary coil.
In another aspect of the present disclosure, the coil antenna may further include a second matching network electrically connected to the secondary coil.
In yet another aspect of the present disclosure, the primary coil may be a first planar coil.
In a further aspect of the present disclosure, the secondary coil may be a second planar coil.
In yet a further aspect of the present disclosure, the primary coil may include two or more turns.
In an aspect of the present disclosure, the secondary coil may include two or more turns.
In accordance with aspects of the disclosure, an interrogation and detection system for detection of surgical implements within a patient's body, is presented. The interrogation and detection system includes an RFID tag configured to transmit a return signal when energized, a signal generator configured to generate an energizing signal for the RFID tag, and a coil antenna operably coupled to the signal generator, the antenna configured to receive a return signal transmitted by the RFID tag, the coil antenna including a coil array. The RFID tag affixed to a surgical implement within the patient's body.
In another aspect of the present disclosure, the coil array may be configured to generate a magnetic flux and steer a direction of the magnetic flux and/or a magnitude of the magnetic flux based on the energizing signal.
In yet another aspect of the present disclosure, the coil array includes a first coil and a second coil. The energizing signal may include a first current and a second current. The first coil and the second coil may be configured to independently be energized by the first current and the second current, respectively.
In a further aspect of the present disclosure, the second coil may be oriented 0, 90, 180, and/or 270 degrees relative to the first coil.
In yet a further aspect of the present disclosure, the first coil of the coil array may be energized with the first current in a clockwise direction and/or a counter-clockwise direction. The second coil of the coil array is energized with the second current in a clockwise direction and/or a counter-clockwise direction.
In accordance with aspects of the disclosure, each coil of the coil array may be arranged in a circular, square, rectangular, and/or oblong configuration.
In an aspect of the present disclosure, each of the first coil and the second coil may be planar coils.
In another aspect of the present disclosure, each of the first coil and the second coil may include one or more turns.
In yet another aspect of the present disclosure, each of the coils of the coil array may include a primary coil and a secondary coil. Each of the coils of the coil array may further include a “turns ratio” between the primary coil to the secondary coil greater than or equal to 1:1. The “turns ratio” is a ratio between a first quantity of turns of the primary coil and a second quantity of turns of the secondary coil.
In accordance with aspects of the disclosure, a coil array configured to receive a return signal transmitted by an RFID tag, includes a first coil configured to generate a first magnetic field and a second coil configured to generate a second magnetic field. The coil array is configured to generate a magnetic flux and steer a direction of the magnetic flux and/or a magnitude of the magnetic flux based on an energizing signal from a signal generator.
In a further aspect of the present disclosure, the energizing signal may include a first current and a second current. The first coil and the second coil may be configured to independently be energized by the first current and the second current, respectively.
In yet a further aspect of the present disclosure, the second coil may be oriented 0, 90, 180, and/or 270 degrees relative to the first coil.
In an aspect of the present disclosure, the first coil of the coil array may be energized with the first current in a clockwise direction and/or a counter-clockwise direction. The second coil of the coil array may be energized with the second current in a clockwise direction and/or a counter-clockwise direction.
In another aspect of the present disclosure, each coil of the coil array may be arranged in a circular, square, rectangular, and/or oblong configuration.
In yet another aspect of the present disclosure, each of the first coil and the second coil may be planar coils.
In a further aspect of the present disclosure, each of the first coil and the second coil may include one or more turns.
In yet a further aspect of the present disclosure, each of the coils of the coil array may include a primary coil and a secondary coil. Each of the coils of the coil array may further include a “turns ratio” between the primary coil to the secondary coil greater than or equal to 1:1. The “turns ratio” is a ratio between a first quantity of turns of the primary coil and a second quantity of turns of the secondary coil.
In accordance with aspects of the disclosure, each of the coils of the coil array may include an inductance greater than or equal to 2.5 uH.
In an aspect of the present disclosure, a method for interrogation and detection of surgical implements within a patient's body is presented. The method includes transmitting an energizing signal by a coil antenna operably coupled to a signal generator, the antenna configured to receive a return signal transmitted by an RFID tag, the coil antenna including a coil array, and receiving a return signal, by the coil array. The coil array is configured to generate a magnetic flux and steer a direction of the magnetic flux and/or a magnitude of the magnetic flux based on the energizing signal.
In another aspect of the present disclosure, the energizing signal may include a first current and a second current. The method may further include energizing, by the signal generator, a first coil of the coil array is energized by the first current in a clockwise direction and/or a counter-clockwise direction, and energizing, by the signal generator, a second coil of the coil array by the second current in a clockwise direction and/or a counter-clockwise direction.
In accordance with aspects of the disclosure, a system for dynamically configuring a secondary air-core coupled coil and exciting magnetic fields is presented. The system includes an RFID tag configured to transmit a return signal when energized, the RFID tag affixed to a surgical implement within a patient's body, a signal generator configured to generate an energizing signal for the RFID tag, and a coil antenna operably coupled to the signal generator, the antenna configured to receive a return signal transmitted by the RFID tag, the coil antenna configured to excite a magnetic field in multiple directions based on the energizing signal.
In yet another aspect of the present disclosure, the coil antenna may include a coil array including a plurality of coils. Each coil of the coil array may include a primary coil and a secondary coil.
In a further aspect of the present disclosure, the coil antenna may further include a coil tuning network configured to tune a quality factor “Q” and/or an operating frequency of the primary coil.
In yet a further aspect of the present disclosure, the tuning network may include a real part match detection network configured to detect the real part of the energizing signal, an imaginary part match detection network configured to detect the imaginary part of the energizing signal, a dynamic matching network configured to tune a quality factor “Q” and/or a first resonant frequency of the primary coil, a processor, and a memory with instructions stored thereon, which when executed by the processor cause the system to detect a real part of the energizing signal, by the real part match detection network, detect a real part of the energizing signal, by the imaginary part match detection network, determine a second resonant frequency for the primary coil, based on the detected real part and detected imaginary part of the energizing signal, and tune, by the dynamic matching network, the primary coil to the second resonant frequency, based on the determination.
In an aspect of the present disclosure, tuning network may further include a power detection network configured to detect a power level from the energizing signal.
In another aspect of the present disclosure, the instructions, when executed, may further cause the system to detect, power detection network, the power level of the energizing signal, determine a third resonant frequency for the primary coil, and tune, by the dynamic matching network, the primary coil to the third resonant frequency, based on the determination.
In yet another aspect of the present disclosure, the coil antenna may further include a termination network configured to enable or disable discrete secondary coils of the coil array.
In a further aspect of the present disclosure, the termination network may include an impedance sensor configured to sense the impedance of each of the secondary coils of the coil array, a step down transformer configured to step down the impedance of each of the secondary coils of the coil array, a dynamic capacitive bank configured to provide a plurality of loads to each of the secondary coils of the coil array via the step down transformer, a processor, and a memory with instructions stored thereon, which when executed by the processor cause the system to determine, by the impedance sensor, the impedance of the return signal, and set the dynamic capacitive bank to one of the plurality of loads based on the determination.
In yet a further aspect of the present disclosure, the secondary coil may be a configurable secondary coil, including a plurality of configurable secondary coil sections. The configurable secondary coil may have a plurality of secondary coil configurations.
In accordance with aspects of the disclosure, the coil antenna may further include a steering network configured to enable at least one of the plurality of secondary coil configurations.
In an aspect of the present disclosure, the system may include a surgical table. The coil antenna may be embedded into the surgical table.
In another aspect of the present disclosure, the coil array may include a first coil and a second coil. The energizing signal may include a first current and a second current. The first coil and the second coil may be configured to independently be energized by the first current and the second current, respectively.
In yet another aspect of the present disclosure, the first coil of the coil array may be energized with the first current in a clockwise direction and/or a counter-clockwise direction. The second coil of the coil array may be energized with the second current in a clockwise direction and/or a counter-clockwise direction.
In accordance with aspects of the disclosure, a coil antenna includes a coil array configured to receive a return signal transmitted by an RFID tag. The coil array includes a first coil configured to generate a first magnetic field and a second coil configured to generate a second magnetic field. The coil array including a plurality of coils configured to generate a magnetic flux and steer a direction of the magnetic flux and/or a magnitude of the magnetic flux based on an energizing signal from a signal generator. Each coil of the coil array includes a primary coil and a secondary coil.
In yet a further aspect of the present disclosure, the coil antenna may further include a coil tuning network configured to tune a quality factor “Q” and/or an operating frequency of each primary coil.
In an aspect of the present disclosure, the tuning network may include a real part match detection network configured to detect the real part of an energizing signal, an imaginary part match detection network configured to detect the imaginary part of the energizing signal, a dynamic matching network configured to tune a quality factor “Q” and/or a first operating frequency of the primary coil, a processor, and a memory. The memory includes instructions stored thereon, which when executed by the processor cause the coil antenna to detect a real part of the energizing signal, by the real part match detection network, detect a real part of the energizing signal, by the imaginary part match detection network, determine a second operating frequency for the primary coil, based on the detected real part and detected imaginary part of the energizing signal, and tune, by the dynamic matching network, the primary coil to the second operating frequency, based on the determination.
In another aspect of the present disclosure, the coil antenna may further include a termination network configured to enable or disable discrete secondary coils of the coil array.
In yet another aspect of the present disclosure, the termination network may include a sensor configured to sense an impedance, a voltage, and/or a current of each of the secondary coils of the coil array.
In a further aspect of the present disclosure, the secondary coil may be a configurable secondary coil, including a plurality of configurable secondary coil sections. The configurable secondary coil having a plurality of secondary coil configurations.
In accordance with aspects of the disclosure, a method for interrogation and detection of surgical implements within a patient's body, includes transmitting an energizing signal by a coil antenna operably coupled to a signal generator, the antenna configured to receive a return signal transmitted by an RFID tag, the coil antenna including a coil array, receiving a return signal, by the coil array. The coil array is configured to generate a magnetic flux and steer a direction of the magnetic flux and/or a magnitude of the magnetic flux based on the energizing signal. The method further includes detecting a real part of the energizing signal, by a real part match detection network; detecting a real part of the energizing signal, by an imaginary part match detection network; determining a second operating frequency for the primary coil, based on the detected real part and detected imaginary part of the energizing signal; and tuning, by a dynamic matching network, the primary coil to the second operating frequency, based on the determination.
In accordance with aspects of the disclosure, a system for real-time dynamically tuning an impedance match between an antenna coil and a signal generator, includes an RFID tag configured to transmit a return signal when energized, the RFID tag affixed to a surgical implement within a patient's body, a signal generator configured to generate an energizing signal for the RFID tag, a coil antenna operably coupled to the signal generator, the antenna configured to receive a return signal transmitted by the RFID tag, and a real-time tuning network configured to dynamically tune the impedance match between the signal generator and the coil antenna.
In yet a further aspect of the present disclosure, the real-time tuning network may include a tuning discriminator configured to determine a real part of the energizing signal and/or an imaginary part of the energizing signal, a phase compensation network configured to dynamically tune a phase of the matching impedance based on the determined imaginary part of the energizing signal, and a magnitude compensation network configured to dynamically tune a magnitude of the matching impedance based on the determined real part of the energizing signal. The imaginary part includes a capacitive signal, an inductive signal and/or a composite signal. The real part includes an energizing signal current and/or an energizing signal voltage.
In an aspect of the present disclosure, the real-time tuning discriminator may include an impedance transform network configured to transform the energizing signal from the signal generator for identification of the real part and the imaginary part of the energizing signal, a rectifier configured to rectify the impedance transformed signal, and a low pass filter configured to filter the rectified signal.
In another aspect of the present disclosure, the real-time tuning network may further include a power detector configured to detect the energizing signal current and/or the energizing signal voltage.
In yet another aspect of the present disclosure, the phase compensation network may include a dynamic capacitive element configured to select a frequency range for the phase of the matching impedance and a transformer configured to reduce a voltage across the dynamic capacitance element.
In a further aspect of the present disclosure, the magnitude compensation network may include a dynamic capacitive element configured to select a frequency range of the magnitude of matching impedance and a transformer configured to reduce a voltage across the dynamic capacitance element.
In yet a further aspect of the present disclosure, the system may further include a processor and a memory, including instructions stored thereon, which, when executed, cause the system to determine an imaginary part of the energizing signal and dynamically tune the phase of the matching impedance based on the determined imaginary part of the energizing signal by the phase compensation network.
In an aspect of the present disclosure, instructions when executed may further cause the system to determine a real part of the energizing signal and dynamically tune, by the magnitude compensation network, the magnitude of the matching impedance based on the determined real part of the energizing signal of the energizing signal.
In another aspect of the present disclosure, the coil antenna may include a primary coil and a secondary coil.
In yet another aspect of the present disclosure, the tuning network may be disposed between the primary coil and the signal generator. The tuning network may be configured to tune a quality factor “Q” and/or an operating frequency of the primary coil.
In a further aspect of the present disclosure, the system may further include a second tuning network electrically coupled to the secondary coil and configured to tune a quality factor “Q” and/or an operating frequency of the secondary coil.
In accordance with aspects of the disclosure, a method for real-time dynamically tuning an impedance match between an antenna coil and a signal generator, includes determining a real part of an energizing signal of the signal generator and/or an imaginary part of an energizing signal of the signal generator and dynamically tuning, by a phase compensation network, a phase of the matching impedance based on the determined imaginary part of the energizing signal.
In yet a further aspect of the present disclosure, the method may further include determining a real part of the energizing signal and dynamically tuning, by a magnitude compensation network, a magnitude of the matching impedance based on the determined real part of the energizing signal of the energizing signal.
In accordance with aspects of the disclosure, a real-time tuning network configured to dynamically tune an impedance match between a signal generator and an antenna, is presented. The real-time tuning network including a real-time tuning discriminator configured to determine a real part of an energizing signal from the signal generator and/or an imaginary part of the energizing signal, a phase compensation network configured to dynamically tune a phase of the matching impedance based on the determined imaginary part of the energizing signal, and a magnitude compensation network configured to dynamically tune a magnitude of the matching impedance based on the determined real part of the energizing signal. The imaginary part includes a capacitive signal, an inductive signal, and/or a composite signal. The real part includes an energizing signal current and/or an energizing signal voltage.
In an aspect of the present disclosure, the real-time tuning discriminator may include an impedance transform network configured to transform the energizing signal from the signal generator for identification of the real part and the imaginary part of the energizing signal, a rectifier configured to rectify the impedance transformed signal, and a low pass filter configured to filter the rectified signal.
In another aspect of the present disclosure, the real-time tuning network may further include a power detector configured to detect the energizing signal current and/or the energizing signal voltage.
In yet another aspect of the present disclosure, the phase compensation network may include a dynamic capacitive element configured to select a frequency range for the phase of the matching impedance and transformer configured to reduce a voltage across the dynamic capacitance element.
In a further aspect of the present disclosure, the magnitude compensation network may include a dynamic capacitive element configured to select a frequency range of the magnitude of matching impedance and a transformer configured to reduce a voltage across the dynamic capacitance element.
In yet a further aspect of the present disclosure, the coil antenna may include a primary coil and a secondary coil.
In an aspect of the present disclosure, the tuning network may be disposed between the primary coil and the signal generator. The tuning network is configured to tune a quality factor “Q” and/or an operating frequency of the primary coil.
In accordance with aspects of the disclosure, a system for matching an impedance between an antenna and a signal generator, includes an RFID tag configured to transmit a return signal when energized, the signal generator configured to generate an energizing signal for the RFID tag, a coil antenna operably coupled to the signal generator, the antenna configured to receive a return signal transmitted by the RFID tag, and a first transformer configured to match the impedance between the signal generator and the antenna. The RFID tag is affixed to a surgical implement within a patient's body.
In another aspect of the present disclosure, the first transformer may include a primary winding and a secondary winding. The system further comprises a capacitor disposed in parallel to the primary winding of the first transformer, the capacitor is configured to match the impedance between the signal generator and the antenna.
In yet another aspect of the present disclosure, the system may further include a matching network disposed between the first transformer and the antenna. The matching network may be configured to match the impedance between the signal generator and the antenna.
In a further aspect of the present disclosure, the matching network may include a fixed matching network and/or a dynamic matching network. The dynamic matching network is configured to dynamically match the impedance between the signal generator and the antenna based on a parameter of the energizing signal.
In yet a further aspect of the present disclosure, the parameter of the energizing signal may include a power level, a frequency, a bandwidth, a voltage, and/or a current.
In accordance with aspects of the disclosure, may further include a second transformer configured to transform an impedance match between the matching network and the antenna. The second transformer may be disposed between the matching network and the antenna.
In an aspect of the present disclosure, the second transformer may be a step up transformer.
In another aspect of the present disclosure, the system may further include a dynamic capacitive element configured to tune the impedance. The dynamic capacitive element may disposed across the primary winding of the second transformer.
In yet another aspect of the present disclosure, the system may further include a sensor configured to sense a signal indicative of a parameter of the energizing signal, a processor, and a memory. The memory includes instructions stored thereon, which when executed cause the system to sense the signal indicative of a parameter of the energizing signal, determine parameter of the energizing signal based on the sensed signal, and dynamically tune the dynamic capacitive element based on the determined parameter of the energizing signal.
In a further aspect of the present disclosure, the second transformer may include a primary winding and a secondary winding. The system further comprises a bulk capacitance disposed across the secondary winding of the second transformer.
In yet a further aspect of the present disclosure, the second transformer may include a step down transformer.
In accordance with aspects of the disclosure, a system for matching an impedance between an antenna and a signal generator, includes an RFID tag configured to transmit a return signal when energized, the signal generator configured to generate an energizing signal for the RFID tag, the antenna operably coupled to the signal generator, the antenna configured to receive a return signal transmitted by the RFID tag, a transformer configured to match the impedance between the signal generator and the antenna, and a dynamic capacitive element configured to tune the impedance, the dynamic capacitive element is disposed across the primary winding of the transformer. The RFID tag affixed to a surgical implement within a patient's body.
In an aspect of the present disclosure, the system may further include a sensor configured to sense a signal indicative of a parameter of the energizing signal, a processor, and a memory. The memory includes instructions stored thereon, which when executed cause the system to sense the signal indicative of a parameter of the energizing signal, determine parameter of the energizing signal based on the sensed signal, and dynamically tune the dynamic capacitive element based on the determined parameter of the energizing signal.
In another aspect of the present disclosure, the parameter of the energizing signal may include a power level, a frequency, a bandwidth, a voltage, and/or a current.
In yet another aspect of the present disclosure, the transformer may include a primary winding and a secondary winding. The system may further include a bulk capacitance disposed across the secondary winding of the transformer.
In a further aspect of the present disclosure, the transformer may be a step down transformer.
In yet a further aspect of the present disclosure, the system may further include a matching network disposed between the transformer and the antenna, and the matching network is configured to match the impedance between the signal generator and the antenna.
In an aspect of the present disclosure, the matching network may include a fixed matching network and/or a dynamic matching network. The dynamic matching network is configured to dynamically match the impedance between the signal generator and the antenna based on a parameter of the energizing signal.
In accordance with aspects of the disclosure, a method for tuning an impedance match between an antenna and a signal generator, the method includes sensing, by a sensor, a signal indicative of a parameter of an energizing signal, determining parameter of the energizing signal based on the sensed signal, and dynamically tuning a dynamic capacitive element based on the determined parameter of the energizing signal. The dynamic capacitive element is disposed across a primary of a transformer disposed between the signal generator and the antenna.
In yet another aspect of the present disclosure, the parameter of the energizing signal may include a power level, a frequency, a bandwidth, a voltage, and/or a current.
In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not drawn to scale, and some of these elements are arbitrarily enlarged or shrunk and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn are not intended to convey any information regarding the actual shape of the particular elements and have been solely selected for ease of recognition in the drawings.
Various aspects of the presently disclosed antennae, RF tags, and articles containing them are described hereinbelow with reference to the drawings.
In the following description, certain specific details are set forth in order to provide a thorough understanding of disclosed aspects. However, one skilled in the relevant art will recognize that aspects may be practiced without one or more of these specific details or with other methods, components, materials, etc. In other instances, well-known structures associated with transmitters, receivers, or transceivers have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the aspects.
Reference throughout this specification to “one aspect” or “an aspect” means that a particular feature, structure, or characteristic described in connection with the aspect is included in at least one aspect. Thus, the appearances of the phrases “in one aspect” or “in an aspect” in various places throughout this specification are not necessarily all referring to the same aspect. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more aspects.
The object 100a may take a variety of forms, for example, instruments, accessories, and/or disposable objects useful in performing surgical procedures. For instance, the object 100a may take the form of scalpels, scissors, forceps, hemostats, and/or clamps. Also, for example, the objects 100a may take the form of surgical sponges, gauze, and/or padding. The object 100a is tagged, carrying, attached, or otherwise coupled to an RFID tag 100. Aspects of the interrogation and detection system 10 disclosed herein are particularly suited to operate with one or more RFID tags 100, which are not accurately tuned to a chosen or selected resonant frequency. Consequently, the RFID tags 100 do not require high manufacturing tolerances or expensive materials and thus may be inexpensive to manufacture.
In use, the medical provider 12 may position the wand 300a approximate the patient 18 in order to detect the presence or absence of the one or more RFID tags 100 and hence an object 100a. The medical provider 12 may, in some aspects, move the wand 300a along and/or across the body of the patient 18. For a detailed description of an exemplary interrogation and detection system, reference may be made to commonly owned U.S. Patent Application Publication No. 2004/0250819 to Blair et al., titled “Apparatus and Method for Detecting Objects Using Tags And Wideband Detection Device,” filed Mar. 29, 2004, the entire contents of which is hereby incorporated by reference herein.
Referring now to
In one aspect of interrogation and detection system 10, the antenna 300 is an antenna 300 configured to be waved over the surgical site 15, e.g., over the body of patient 18. For example, the antenna 300 may be held over the body of the patient 18 at the height of about four or about five inches while attempting to detect an RFID tag so that the user may detect confirm the presence of objects 100a within the body of patient 18.
The term “read range,” as used in this disclosure, includes the distance from an antenna 300 (e.g., a reader coil) of an interrogation and detection system 10 and the geometric center of the RFID tag 100 (
For a hand-held accessory, the physical size is important. The accessory needs to be constructed using a form factor that is conducive to use in the intended application. For typical RFID applications, where communication between an interrogation and detection system 10 and an RFID tag 100 (
One of the limiting factors in terms of interrogation and detection system 10 performance in the field of RFID relates to the optimal loading conditions an antenna coil may present to signal generator 200 (
Frequently, generators 200 of RFID systems are intended to interface to a 50-ohm characteristic impedance antenna. This convention allows developers to abstract the development of reader solutions from the coil or antenna solutions. A typical antenna coil presents a predominantly reactive (inductive, Z=Im{ }) load impedance at the coil terminals. A matching network is used to interface a predominantly real generator (e.g., reader) output impedance to a predominantly reactive coil input impedance. This is usually done in two steps, with one aspect of the matching network being used to accommodate the real part of the target load and another aspect of the matching network canceling out the reactive part of the coil load. The end result is an optimal transmission of the RF energy to and from the generator and antenna 300 elements. In practical applications, the acceptable range of the complex part of the load impedance in the antenna coil is limited due to the topologies and component values required to construct an effective matching network. As a rule of thumb, the coil inductance may nominally be between about 0.5 uH and about 2.5 uH for practical matching networks. Coils with reactive impedances outside of this range may be difficult to match using conventional methods and susceptible to component tolerance and drift.
A coil's inductive impedance component is largely a function of two main characteristics. The coil area, and the number of turns in the coil. Magnetic field vector magnitude, and thus the ability to energize and communicate with a passive tag for a given coil current is a direct function of both the coil area and the number of turns in the coil. In other words, as the coil area and/or the number of turns in the coil increase, the read range increases. Unfortunately, for coils intended to be used in long-range wireless magnetic-based communications, the inductance due to the coil area quickly eliminates the option of adding turns to the coil due to the increase in the inductive component of the impedance. Inductance is based on the square of the number of turns. Ultimately, the ability to maximize the performance of an antenna coil directly through physical characteristics is limited by the amount of inductive load the coil presents to the matching network. A method that allows for increasing the coil inductance while maintaining a practical matching load impedance is of interest. The disclosed technologies leverage non-traditional methods that enable either an increase in coil area or an increase in the number of coil turns may achieve improved read range and/or sensitivity to antenna 300/RFID tag 100 orientation.
In addition to the limitations relating to the allowed range of reactive impedance described above, is a limitation in the ability to tune an antenna to operate at resonance. Resonance in this context is a scenario where an inductive coil is loaded with an equal and opposite capacitive load (either in series or in parallel). The resultant circuit in the ideal case is capable of sustaining an oscillation at the resonance frequency indefinitely. According to the present disclosure, resonant circuit techniques are used to improve coil-type antenna performance by providing a dimension of performance gain, frequently referred to as a quality factor (Q). The quality factor “Q” of an antenna is a way of describing the ratio of the reactive part of the impedance to the real part of the impedance (Im{ }/Re{ }). The reactive part of impedance is theoretically a lossless impedance, and the real part of the impedance is theoretically totally lossy. In other words, the energy imparted to a resonant coil antenna oscillates with an efficiency that is described by the ratio of the lossless impedance to the lossy impedance. As the inductive and capacitive components are tuned to be equal to each other at the target operating frequency, the quality factor increases, and the ratio of energy in the lossless components of the impedance is increased when compared to the energy dissipated in the lossy part of the impedance. Maximizing the quality factor “Q” is, in essence, a way of realizing free “gain” in a wireless communications channel. There are limitations in the allowed magnitude of the quality factor in conventional communications channels, but the limitation we are specifically addressing with this solution relates to the ability to match a generator output channel to an antenna 300 a resonant coil input.
For ideal parallel resonant circuits, the magnitude of the impedance approaches infinity (open circuit), and the voltage across the coil element is maximized. For ideal serial resonant circuits, the impedance approaches zero “0” (short circuit), and the current through the coil element is maximized. Reader technologies are not designed to drive open or short circuit loads, so we are forced to de-tune (tune away from resonance) the resonant properties in order to match a reader to a coil from a practical perspective. This results in a reduction of the free gain that may be realized via the quality factor “Q.” Furthermore, changes in the dielectric properties of the space around the antenna coils will shift the resonant frequency of the coil or degrade the coil performance due to an increase in the real part of the coil impedance.
With reference to
The transformer 310 generally includes a primary coil 302, a secondary coil 304, and a core 306 made of a non-magnetic insulating material (e.g., an air-core and/or a polymer). Air has a dielectric constant of one “1” and a loss tangent of about zero “0.” It is contemplated that other materials may be used for the core that have sufficiently low loss tangents at and/or around the frequency of operation of the antenna 300 (e.g., polyimide, Polytetrafluoroethylene “PTFE,” etc.). The primary coil 302 and secondary coil 304 may be mounted to an insulating material. The first matching network 410 is configured to match an input impedance of the primary coil 302 to an output impedance of the generator 200 (
Each of the primary coil 302 and the secondary coil 304 include one or more turns. In aspects, the primary coil 302 and the secondary coil 304 may have the same or a different number of turns than each other. For example, the primary coil 302 may have one turn, and the secondary coil 304 may have two turns for a “turns ratio” of 1:1. A “turns ratio” is the ratio of a transformer's primary and secondary windings with respect to each other. The primary coil 302 and/or the secondary coil 304 may be but is not limited to, any suitable shape, for example, spiral, square, elliptical, and/or circular. In aspects, primary coil 302 and/or the secondary coil 304 may have any suitable cross-section. For example, the cross-section of the primary coil 302 and/or the secondary coil 304 may be, but is not limited to, coaxial, planar, “C” shaped, and/or tube-shaped. The primary coil 302 and the secondary coil 304 may be any suitable width.
The air-core 306 is configured to provide a path for a magnetic field to flow around to induce a voltage between the primary coil 302 and the secondary coil 304. By adding an air-core 306 coupled secondary coil 304 to a traditional coil antenna, the challenges associated with both of the points discussed above are reduced. It is possible to incorporate several turns (two or more) on the secondary coil 304 while maintaining a reasonable matching impedance as presented at the primary coil 302 input terminals. This is due to the construction of a relatively weakly coupled transformer 310 with “turns ratio” 1:N, where “N” is the number of turns on the secondary coil 304. The transformer 310 acts as an impedance transformer, essentially stepping down the load (reactance) by a ratio of 1/N2. The net result is that the inductance measured at the primary coil 302 terminals increases at a rate less than N2, allowing for secondary coil 304 inductance values in excess of about 2.5 uH while maintaining primary coil 302 reactance components that can be reasonably matched from a practical perspective. Additionally, the secondary coil 304 can be tuned to a resonance closer to the target frequency of operation. As the load reflects through the air-core coupled transformer 310, it is reduced (parallel resonance), and the parasitic impedances that are inherent to the circuit shift the resonance as seen by the primary coil 302, further allowing a practical tuning situation.
The primary matching network 410 is configured to match the impedance between the primary coil 302 and the signal generator 200 to minimize mismatches that can cause the RF energy to be reflected back into the signal generator 200 instead of propagating into the primary coil 302. The secondary matching network 420 is configured to match the impedance between the secondary coil 304 and the primary coil 302, and between the secondary coil 304 and the tag coil (not shown) to minimize mismatches that can cause the RF energy to be reflected back into the signal generator 200 instead of propagating into the tag coil.
Referring to
Referring to
Referring to
Large multi-turn magnetic field coil antennas have inherently low self-resonant frequencies due to parasitic capacitances. When designing a near field radio frequency identification reader antenna, it is desirable to use a coil design that is primarily inductive in order to ensure that the current circulating through the coil conducts through the entire coil. Doing so results in maximized field strengths for a given coil current. As the parasitic capacitance increases, the currents in the coil begin to return to the source through undesirable paths, thus reducing the effectiveness of the coil. Adding to the challenge is the competing objective of designing for high coil factor “Q” (the ratio of the reactive impedance to the real impedance). A high factor “Q” coil is a coil where the ohmic real part of the resistance is minimized while the coil inductance is maximized. In aspects, increasing quality factor “Q” may be performed by increasing the conductor thickness (to compensate for skin-depth) and/or conductor surface area (or width in the case of a flat conductor). However, the parasitic capacitance between two conductors is a function of the conductor area as well as the distance between the conductors. As such, increasing the width of the conductor results in a corresponding decrease in the self-resonant frequency. For an inductive coil, increasing the separation between adjacent coil windings reaches a point of diminishing returns as the coupling efficiency between the individual coils reduces when the distance between the coils is increased.
Referring to
A first turn conductor 902 of staggered coil 900 is located in a parallel relation and in an offset manner to the second turn conductor 904 of staggered coil 900, and in vertical and/or horizontal relation to one another in an X, Y, Z coordinate system. The first turn conductor 902 and second turn conductor 904 have a core 906 between them. The core 906 may be air or other dielectric material suitable as an insulator. Although two turns are shown, any suitable number of turns (e.g., conductive layers) may be used by offsetting the additional turns in vertical and/or horizontal relation to the previous turn conductor. For example, the staggered coil 900 may include three turns, where the third turn is offset from the second turn conductor 904 in a similar manner to how the second turn conductor 904 is offset from the first turn conductor 902.
The first turn conductor 902 includes an inner edge 902a and an outer edge 902b. The second turn conductor 904 includes an inner edge 904a and an outer edge 904b. The first turn conductor 902 may overlap the second turn conductor 904 of the staggered coil 900, where a substantial portion (e.g., about >50%) of the second turn conductor 904 is not overlapped by the first turn conductor 902.
The first turn conductor 902 and/or the second turn conductor 904 may be but are not limited to, any suitable shape, for example, spiral, square, elliptical, and/or circular. In aspects, first turn conductor 902 and/or the second turn conductor 904 may have any suitable cross-section. For example, the cross-section of the first turn conductor 902 and/or the second turn conductor 904 may be, but is not limited to, coaxial, planar, “C” shaped, and/or tube-shaped. The first turn conductor 902 and/or the second turn conductor 904 may be any suitable width (for example, approximately 1 cm wide copper). It is contemplated that the first turn conductor 902 and/or the second turn conductor 904 are monolithic, or each turn of the coil may be a single piece, electrically connected to the next turn.
This staggered coil 900 configuration combines optimized conductor width and an optimized coil-to-coil configuration with a staggered individual coil element design. In aspects, this staggered coil 900 configuration may be packaged into a thin mattress-like coil array intended for use as a scanning accessory in the real-time detection of tagged surgical items in an operating room environment. The staggered coil 900 configuration has advantages over other implementations, such as a traditional planar coil due to the preservation of the coil area, which is a dominant characteristic of the coil performance in terms of field strength. Furthermore, the staggered configuration has the added advantage of improving radiolucency when compared to a traditional coaxial coil design due to the reduced number of coexistent x-y plane conductive layers in multi-turn coils. The staggered coil 900 configuration is effective in applications where a single coil is driven directly, as well as applications where an air-core coupled secondary is utilized. For example, in a staggered coil 900 configuration, the reduction in parasitic capacitance and subsequent increase in self-resonant frequency may be highly beneficial, where maximizing coil inductance or improving coil efficiency are advantageous.
Referring to
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Referring to
For near-field RFID communications systems, the reader antenna coil (e.g., antenna 300 of
For scenarios where the tag is able to be oriented in any direction over a fixed reader coil/reader coil array, every point in space above the coil/array will have a magnetic field “H” vector that is optimal to a specific RFID tag 100 (
With reference to
Referring to
For example, in
For example, in
For example, in
It is contemplated that the current “I” magnitude for each of the individual coils 1702-1708 may include a positive or negative value, and the current “I” direction for each of the individual coils may vary in a clockwise or counterclockwise manner, in order to enable the steering of the magnetic flux “B” direction and/or magnitude to suit the application.
Referring to
For applications that provide both detection and identification of tagged surgical items, it may be desirable to implement a larger static antenna array 1300 (
For typical RFID applications, where communication between an antenna 300 (
As mentioned previously, this disclosure combines the advantages of the air-core coupled secondary construction (
Referring to
The controller 2240 is configured to receive signals from the real part match detection network 2210, the imaginary part match detection network 2220, the power detection network 2230, and control the dynamic matching network 2250 based on the detected signals. The controller 2240 includes a processor and memory, and is configured to execute instructions stored on the memory.
The dynamic matching network 2250 is configured to tune the quality factor “Q” and/or resonant frequency of the primary coil 1702a, 1704a, 1706a, 1708a of the coil array 1700 (
The coil termination network 2300 is configured to enable or disable discrete secondary coils 1702b, 1704b, 1706b, 1708b of the coil array 1700. The coil termination network 2300 may eliminate a resonant network (open circuit), it may short a coil element, or it may terminate the coil based on a loading condition (by switching in different value capacitors) that shifts the resonant characteristics to a region in the frequency domain that makes it appear to be out-of-circuit from a magnetic field perspective and/or from the loading it presents to the detection system 10 (
Referring to
With reference to
For example, the system 3300 may include four (2×2) primary coils 3304a, 3304b, 3304c, 3304d, and a configurable air-core coupled secondary coil 3306. Each primary coil 3304a, 3304b, 3304c, 3304d has an associated coil tuning network 2200. The configurable air-core coupled secondary coil 3306 generally includes a first section 3306a, a second section 3306b, a third section 3306c, and a fourth section 3306d. It is contemplated that any suitable number of sections 3306a, 3306b, 3306c, 3306d may be used. The configurable air-core coupled secondary coil 3306 has a configurable coil termination network 2300.
The steering network 2040 is used to configure the configurable air-core coupled secondary coil 3306 configuration best suited to excite an RFID tag 100 in a given orientation. The configurable termination 2200 and steering networks 2040 are controlled by the controller 2240. The steering networks 2040 may be located in the middle of and/or between the various sections of the configurable air-core coupled secondary coil 3306 to enable the switching in and out of various sections 3306a, 3306b, 3306c, 3306d of the configurable air-core coupled secondary coil 3306.
Referring to
Typically, autotuning is conducted as a discrete step or state in the system operation. Autotuning is done relatively infrequently and generally requires disabling the RFID communications channel. In surgical applications, that is an unacceptable scenario, as the antenna loading is potentially changing constantly based on tissue properties, and it would be impractical to require a re-tuning step multiple times during a scanning sequence, especially for hand-held scanning accessories.
For applications that provide both detection and identification of tagged surgical items, unique technology implementations, and tuning methods are required to adapt the dynamic loading conditions presented in the operating room surgical setting. Specifically, for RFID applications, a load presented to an antenna 300 or an antenna array 1700 (
For optimal power transfer into the field, the interface between the generator 200 and the antenna 300 needs to be tuned in real-time or near real-time in order to compensate for a continuously variable loading state.
Referring to
Referring to
The Z-transform network 3810 is configured to analyze the energizing signal from the signal generator 200 for identification of the imaginary part of the energizing signal. This frequency domain representation of the energizing signal is then communicated to the rectifier 3822a, 3822b for rectification. The rectifier 3822a, 3822b may include one or more diodes which convert the alternating current signal (AC) of the energizing signal to a direct current (DC) signal (with some AC artifacts). This DC signal is then filtered by the LPF 3824a, 3824b to remove any residual AC artifacts (e.g., ripple and/or the fundamental frequency of the energizing signal). The LPF 3824a, 3824b, may include a passive (e.g., an R/C network) or an active configuration (e.g., an integrator). The output of the LPF 3824a, 3824b, includes the capacitive signal, the inductive signal, and/or the energizing signal current. The capacitive signal and the inductive signal may be combined into the composite signal by a differential to single-ended converter (e.g., a difference amplifier). The composite signal may be used by the controller 2240 for tuning the impedance magnitude provided to the antenna 300.
The power detector 2230 detects the power level of the energizing signal (e.g., about 1 W to about 10 W typically) by sampling the energizing signal (e.g., by a coupler), rectifying the sampled signal (e.g., by a diode), and processing the signal by adding gain before communicating it to the controller 2240 as the energizing signal voltage.
The controller 2240 is configured to determine the optimal impedance match for the antenna 300 based on the capacitive signal, the inductive signal, the energizing signal current, the energizing signal voltage, and/or the composite signal. The controller 2240 automatically tunes the impedance phase and impedance magnitude of the antenna 300 in real-time based on the determined optimal impedance match. In aspects, the controller 2240 may include multiple independent control loops or may be comprised of several nested control loops for improved stability. The nesting order may be determined by the loop time-constant and may be arranged in multiple ways that optimize the total system response.
With reference to
The magnitude compensation network 3850 is configured to tune the magnitude of impedance match provided to the antenna 300, in real-time. The magnitude compensation network 3850 generally includes one or more resistors, one or more diodes, and a voltage-controlled dynamic capacitance element 3856 configured to be controlled by the range select signal from the controller 2240. The magnitude adjust signal is communicated from the controller 2240 to the magnitude compensation network 3850 and causes the magnitude compensation network 3850 to increase or decrease the magnitude of the impedance match. In aspects, the magnitude compensation network 3850 may include one or more transformers 3852 (e.g., a magnetic-based transformer) in order to reduce the voltage across the dynamic capacitance element 3856. In aspects, the magnitude compensation network 3850 may be used for the tuning networks 410 and 420 of
For the case of an air-core coupled secondary coil 420 (e.g.,
The field strength at a specific distance or “read range” from the antenna 300 is a function of several physical parameters. These parameters may include the air gap that exists between the antenna 300 (
Referring to
An additional advantage to measuring the antenna coil quality factor “Q” for use in the determination of the required output power needed to achieve a target field strength at a target distance from the antenna 300 relates to the information it provides in terms of the scanning technique for hand-held scanning accessories. The controller 2240 can be programmed with target limits for the quality factor “Q,” where the physical proximity characteristics of the scanning accessory with respect to the patient tissue can be established. These limits may be used to provide real-time feedback to the operator in order to improve the scanning efficiency and effectiveness. Specifically, the quality factor “Q” may be interpreted to indicate whether or not the antenna 300 is too close (air gap) to the patient, it can indicate if the antenna 300 is too far away, and the system 3800 can indicate if the tissue load on the accessory is outside of the acceptable range. Furthermore, it is possible that the quality factor “Q” in conjunction with the coil inductance (the phase) and coil magnitude may indicate the presence of interfering objects in the field, like metal instrumentation.
In aspects, the system 3800 may utilize a single voltage or current sensor alone, with the compensation routine adjusting a resonance of a secondary coil of the antenna 300 in order to maximize the sensed parameter. The simplified routine may incorporate a simple set-point dither technique, where the antenna 300 resonant frequency and/or Q-factor is adjusted using binary reduction based on the polarity of the sensed parameter (voltage and/or current) delta.
Referring to
Referring to
Referring now to
Initially, at step 4402, the signal generator 4402 transmits an energizing signal to an antenna 300, to which it is operably coupled. The energizing signal is configured to energize an RFID tag 100 (
Next, at step 4404, the controller 2240 determines a real part and/or an imaginary part of the energizing signal by a tuning discriminator 3802 of the system 3800, which is configured to generate signals used for determining the real part (e.g., a current and/or a voltage) and/or imaginary part (e.g., a phase) of the energizing signal. For example, the real part of the energizing signal may be about 10.2 V.
Next, at step 4406, the controller 2240 dynamically tunes a phase of a matching impedance based on the determined imaginary part of the energizing signal. The controller 2240 may tune the phase of the matching impedance based on a phase compensation network 3840.
Next, at step 4408, the controller 2240 dynamically tunes a magnitude of a matching impedance based on the determined real part of the energizing signal. The controller 2240 may tune the magnitude of the matching impedance based on a magnitude compensation network 3840.
Referring to
Referring to
Where “Lloop” is the loop inductance, “D” is the inner diameter of the loop, “d” is the width of the loop conductor, “ur” is the relative permeability, and “uo” is the permeability of free space.
For example, in a case where an antenna inductance is approximately 1.174 uH, using the loop inductance equation, then for a 1 cm wide copper conductor, the diameter of the antenna would calculate out to be about 47.5 cm. This is a fairly large antenna. However, it may be desirable to have an even larger antenna or to have one with more turns. This could lead to antennas with inductances about ten times or twenty times the value that gives a 50 ohm matched load. Generally, the use of a matching network with this large an inductance may result in unusable component values or simply not be possible.
As the inductance of the antenna increases, the smaller the capacitance that is used in the matching network. Thus, making the loop antenna increasingly difficult to manufacture, and the effectiveness of the antenna may be reduced. For example, for a matching network for a 5.87 uH antenna, the matching network is approximately a 6.9 pF capacitor in parallel with the loop antenna. Thus, at this low a level of capacitance, it is entirely possible the manufacturing process may result in a parasitic capacitance that is greater than this value without even adding a discrete component (e.g., a discrete capacitor). This could be the result of cable parasitics or the parasitic capacitance present in the turns of a multi-turn antenna.
This disclosed technology addresses this issue through the use of a transformer. Adding a transformer element between the tuning network and the reader (e.g., the generator output) will allow the development of a higher impedance matching network that can then be transformed down to the 50 ohms that the reader is expecting. In aspects, the transformer will change the impedance of the matching network by the square root of the “turns ratio.”
Z
p
Z
s
/n
2
For example, in the case of the matching network above, the impedance of the matching network transforms down to 50 ohms. In a case where the impedance on the primary of the transformer is 50 and on the secondary the impedance is 500 ohms, then a transformer with a “turns ratio” (N) of √{square root over (10)} or 3.16 is required.
Although, typically represented as an ideal circuit that simply translates voltages, currents, and impedances to other levels, practical transformers have additional parasitic components that can play a real role in the way a circuit works. At a minimum, these parasitics must be accounted for, while in a well-designed circuit, the parasitic components can be used as part of the impedance matching network.
Impedance matching networks come in many different topologies. They can have series inductances, parallel inductances, or parallel capacitances or other configurations. Transformers can be used to replace the discrete impedance matching network components if they are carefully designed.
Referring to
Referring to
The equation for reflecting a capacitance through a transformer is: Cpri=n2Csec. This means that any capacitance placed on the secondary winding 4702b of the transformer 4702 will get multiplied by the “turns ratio” squared (N2) on the primary. In the case of the previous example, N2=10, where the “turns ratio” N is 3.16. Thus, a relatively small capacitance of 10.3 pF on the primary is needed to achieve our matching network component. For example, a capacitance of 10.3 pF could be realized by a discrete component and/or by embedded printed circuit board capacitance. A benefit of this approach is that leakage inductance and magnetizing inductance will be reduced as they are reflected through the transformer 4702.
Referring to
In aspects, the system 4900 enables dynamically tuning of an antenna resonance 410 (
Referring to
The dynamic capacitive element 5004 is configured to provide a “trimming” capacitance to help fine tune the antenna resonance 300. The dynamic capacitive element 5004 is an element that acts as a capacitive reactance and is tunable by an analog and/or digital signal. The dynamic capacitive element 5004 may include a varactor. For example, if the dynamic capacitive element 5004 is on the primary winding 4702a of the transformer 4702, then the value of the dynamic capacitive element 5004 will be reduced by “turns ratio” squared (N2) as it gets reflected through the transformer 4702. For example, if the dynamic capacitive element 5004 was to have a capacitance range of about 200 pF and “turns ratio” squared (N2)=10, then on the secondary winding, the range would only be 20 pF. If our turning requirements called for 100 pF, then this dynamic capacitive element 5004 would not be able to tune the circuit. If instead an approximately 90 pF high voltage bulk capacitance was used on the secondary winding 4702b, then the tunable range of the circuit would be about 90 pF to about 110 pF.
In aspects, the controller 2240 may be configured to control the value of the dynamic capacitive element 5004. For example, the controller 2240 may control a tuning voltage of the dynamic capacitive element 5004 to tune the resonance of the antenna 300.
Referring to
The first transformer 5104 may be configured to transform the typical 50 ohm impedance of the generator 200 to an impedance other than 50 ohms. In aspects, the first transformer 5104 may include a step-up transformer or a step-down transformer. Careful design will allow the use of transformer parasitics to be part of the matching network. For example, if the parasitic capacitor 4704 was to have a capacitance of about 20 pF and the first transformer 5104 has a N2=10, then on the secondary winding 5104b the capacitance would be about 200 pF which may be an appropriate value for the matching network.
The matching network 5102, may include a fixed matching network (e.g., fixed capacitor and/or inductor values) and/or may include a dynamic matching network 2250 (
The dynamic capacitive element 5004 is disposed on a primary winding 4702a of the second transformer 4702. The dynamic capacitive element 5004 is configured to provide a tunable capacitance for the antenna resonance whose voltage exposure is limited by the transformer. The controller 2240 may be configured to generate a signal for tuning the capacitance value of the dynamic capacitive element 5004.
The second transformer 4702 is configured to transform the impedance of the dynamic capacitive element 5102 to create the appropriate antenna resonance 300. In aspects, the system may further include a bulk capacitance 5002 configured to adjust the tuning range of the dynamic capacitive element 5004.
The antenna 300 may include a coil antenna, a loop antenna, an antenna array, and/or any other suitable antenna arrangement. For example, the system 5100, may be used to match a dipole antenna to a signal generator 200. In aspects, the second transformer may be a step-down transformer.
Further Aspects of the present disclosure include the following examples:
Example 1. An interrogation and detection system for detection of surgical implements within a body of a patient, the interrogation and detection system comprising:
Example 2. The system of Example 1, wherein a “turns ratio” between the primary coil and the secondary coil is greater than or equal to 1:1, wherein the “turns ratio” is a ratio between a first quantity of turns of the primary coil and a second quantity of turns of the secondary coil.
Example 3. The system of Example 1, wherein the secondary coil includes a resonant frequency within 10% of an operating frequency of the return signal.
Example 4. The system of Example 1, wherein the secondary coil includes an inductance greater than or equal to 2.5 uH.
Example 5. The system of Example 1, wherein the coil antenna further includes a first matching network electrically connected to the primary coil, wherein the first matching network is configured to match an input impedance of the primary coil to an output impedance of the signal generator.
Example 6. The system of Example 1, wherein the coil antenna further includes a second matching network electrically connected to the secondary coil, wherein the second matching network is configured to match an input impedance of the secondary coil to an output impedance of the primary coil.
Example 7. The system of Example 1, wherein the primary coil is a first planar coil.
Example 8. The system of Example 7, wherein the secondary coil is a second planar coil.
Example 9. The system of Example 7, wherein the primary coil includes a first turn and a second turn.
Example 10. The system of Example 9, wherein the first turn of the primary coil and the second turn of the primary coil are arranged in an offset manner in a vertical and a horizontal orientation.
Example 11. The system of Example 8, wherein the secondary coil includes a first turn and a second turn.
Example 12. The system of Example 11, wherein the first turn of the primary coil and the second turn of the primary coil are arranged in an offset manner in a vertical and a horizontal orientation.
Example 13. A coil antenna configured to receive a return signal transmitted by an RFID tag, the coil antenna comprising:
Example 14. The coil antenna of Example 13, wherein the primary coil and the secondary coil are each planar coils.
Example 15. The coil antenna of Example 13, wherein the primary coil includes a conductor.
Example 16. The coil antenna of Example 15, wherein the conductor of the primary coil includes a conductor having a configuration including at least one of coaxial, planar, a “C” shaped transverse cross-sectional shape, or tube shaped transverse cross-sectional shape.
Example 17. The coil antenna of Example 13, wherein a “turns ratio” between the primary coil and the secondary coil is greater than or equal to 1:1, wherein the “turns ratio” is a ratio between a first quantity of turns of the primary coil and a second quantity of turns of the secondary coil.
Example 18. The coil antenna of Example 13, wherein the secondary coil includes a resonant frequency within 10% of an operating frequency of the return signal.
Example 19. A method for inventory control of tagged items, the method comprising:
Example 20. The method of Example 19, further comprising:
Example 21. A coil configured to receive a return signal transmitted by an RFID tag, the coil comprising:
Example 22. The coil of Example 21, wherein the first turn conductor is located in parallel relation and an offset manner to the second turn conductor,
Example 23. The coil of Example 21, wherein the coil is arranged in at least one of a circular, square, rectangular, or oblong configuration.
Example 24. The coil of Example 21, wherein the first turn conductor overlaps the second turn conductor of the staggered coil, where a substantial portion of the second turn conductor is not overlapped by the first turn conductor.
Example 25. A coil antenna configured to receive a return signal transmitted by an RFID tag, the coil antenna comprising:
Example 26. The coil antenna of Example 25, further comprising a core configured to couple electromagnetic energy from the secondary coil to and from the primary coil, wherein the core includes a non-magnetic insulating material,
Example 27. The coil antenna of Example 25, wherein a “turns ratio” between the primary coil and the secondary coil is greater than or equal to 1:1, wherein the “turns ratio” is a ratio between a first quantity of turns of the primary coil and a second quantity of turns of the secondary coil.
Example 28. The coil antenna of Example 25, wherein the secondary coil includes a resonant frequency within 10% of an operating frequency of the return signal.
Example 29. The coil antenna of Example 25, wherein the secondary coil includes an inductance greater than or equal to 2.5 uH.
Example 30. The coil antenna of Example 25, wherein the coil antenna further includes a first matching network electrically connected to the primary coil, wherein the first matching network is configured to match an input impedance of the primary coil to an output impedance of the signal generator.
Example 31. An interrogation and detection system for detection of surgical implements within a patient's body, the interrogation and detection system comprising:
Example 32. The system of Example 31, wherein the secondary coil is air-core coupled to the primary coil.
Example 33. The system of Example 31, wherein a “turns ratio” between the primary coil to the secondary coil is greater than or equal to 1:1, wherein the “turns ratio” is a ratio between a first quantity of turns of the primary coil and a second quantity of turns of the secondary coil.
Example 34. The system of Example 31, wherein the secondary coil includes an inductance greater than or equal to 2.5 uH.
Example 35. The system of Example 31, wherein the coil antenna further includes a first matching network electrically connected to the primary coil.
Example 36. The system of Example 31, wherein the coil antenna further includes a second matching network electrically connected to the secondary coil.
Example 37. The system of Example 31, wherein the primary coil is a first planar coil.
Example 38. The system of Example 31, wherein the secondary coil is a second planar coil.
Example 39. The system of Example 37, wherein the primary coil includes one or more turns.
Example 40. The system of Example 38, wherein the secondary coil includes one or more turns.
Example 41. An interrogation and detection system for detection of surgical implements within a patient's body, the interrogation and detection system comprising:
Example 42. The system of Example 41, wherein the coil array is configured to generate a magnetic flux and steer at least one of a direction of the magnetic flux or a magnitude of the magnetic flux based on the energizing signal.
Example 43. The system of Example 41, wherein the coil array includes a first coil and a second coil,
Example 44. The system of Example 43, wherein the second coil is oriented at least one of 0, 90, 180, or 270 degrees relative to the first coil.
Example 45. The system of Example 44, wherein the first coil of the coil array is energized with the first current in at least one of a clockwise direction or a counter-clockwise direction, and
Example 46. The system of Example 43, wherein each coil of the coil array is arranged in at least one of a circular, square, rectangular, or oblong configuration.
Example 47. The system of Example 43, wherein each of the first coil and the second coil are planar coils.
Example 48. The system of Example 43, wherein each of the first coil and the second coil include one or more turns.
Example 49. The system of Example 41, wherein each of the coils of the coil array include a primary coil and a secondary coil,
Example 50. A coil array configured to receive a return signal transmitted by an RFID tag, the coil array comprising:
Example 51. The coil array of Example 50, wherein the energizing signal includes a first current and a second current, and
Example 52. The coil array of Example 50, wherein the second coil is oriented at least one of 0, 90, 180, or 270 degrees relative to the first coil.
Example 53. The coil array of Example 52, wherein the first coil of the coil array is energized with the first current in at least one of a clockwise direction or a counter-clockwise direction, and
Example 54. The coil array of Example 51, wherein each coil of the coil array is arranged in at least one of a circular, square, rectangular, or oblong configuration.
Example 55. The coil array of Example 51, wherein each of the first coil and the second coil are planar coils.
Example 56. The coil array of Example 51, wherein each of the first coil and the second coil include one or more turns.
Example 57. The coil array of Example 50, wherein each of the coils of the coil array include a primary coil and a secondary coil,
Example 58. The coil array of Example 50, wherein each of the coils of the coil array includes an inductance greater than or equal to 2.5 uH.
Example 59. A method for interrogation and detection of surgical implements within a patient's body, the method comprising:
Example 60. The method of Example 59, wherein the energizing signal includes a first current and a second current, and
Example 61. A system for matching an impedance between an antenna and a signal generator, the system comprising:
Example 62. The system of Example 61, wherein the first transformer includes a primary winding and a secondary winding,
Example 63. The system of Example 61, further comprising a matching network disposed between the first transformer and the antenna, and the matching network is configured to match the impedance between the signal generator and the antenna.
Example 64. The system of Example 63, wherein the matching network includes at least one of a fixed matching network or a dynamic matching network, wherein the dynamic matching network is configured to dynamically match the impedance between the signal generator and the antenna based on a parameter of the energizing signal.
Example 65. The system of Example 64, wherein the parameter of the energizing signal includes at least one of a power level, a frequency, a bandwidth, a voltage, or a current.
Example 66. The system of Example 63, further comprising a second transformer configured to transform an impedance match between the matching network and the antenna, the second transformer is disposed between the matching network and the antenna.
Example 67. The system of Example 66, wherein the second transformer is a step up transformer.
Example 68. The system of Example 67, further comprising a dynamic capacitive element configured to tune the impedance, the dynamic capacitive element is disposed across the primary winding of the second transformer.
Example 69. The system of Example 68, further comprising:
Example 70. The system of Example 66, wherein the second transformer includes a primary winding and a secondary winding, and
Example 71. The system of Example 66, wherein the second transformer is a step down transformer.
Example 72. A system for matching an impedance between an antenna and a signal generator, the system comprising:
Example 73. The system of Example 72, further comprising:
Example 74. The system of Example 73, wherein the parameter of the energizing signal includes at least one of a power level, a frequency, a bandwidth, a voltage, or a current.
Example 75. The system of Example 73, wherein the transformer includes a primary winding and a secondary winding, and
Example 76. The system of Example 72, wherein the transformer is a step down transformer.
Example 77. The system of Example 72, further comprising a matching network disposed between the transformer and the antenna, and the matching network is configured to match the impedance between the signal generator and the antenna.
Example 78. The system of Example 77, wherein the matching network includes at least one of a fixed matching network or a dynamic matching network, wherein the dynamic matching network is configured to dynamically match the impedance between the signal generator and the antenna based on a parameter of the energizing signal.
Example 79. A method for tuning an impedance match between an antenna and a signal generator, the method comprising:
Example 80. The method of Example 79, wherein the parameter of the energizing signal includes at least one of a power level, a frequency, a bandwidth, a voltage, or a current.
Example 81. A system for real-time dynamically tuning an impedance match between an antenna and a signal generator, the system comprising:
Example 82. The system of Example 81, wherein the real-time tuning network includes:
Example 83. The system of Example 82, wherein the real-time tuning discriminator includes:
Example 84. The system of Example 82, wherein the real-time tuning network further includes a power detector configured to detect at least one of the energizing signal current or the energizing signal voltage.
Example 85. The system of Example 82, wherein the phase compensation network includes:
Example 86. The system of Example 82, wherein the magnitude compensation network includes:
Example 87. The system of Example 83, further comprising:
Example 88. The system of Example 87, wherein the instructions when executed further cause the system to:
Example 89. The system of Example 82, wherein the coil antenna includes:
Example 90. The system of Example 88, wherein the tuning network is disposed between the primary coil and the signal generator, and
Example 91. The system of Example 89, further comprising a second tuning network electrically coupled to the secondary coil and configured to tune at least one of a quality factor “Q” or an operating frequency of the secondary coil.
Example 92. A method for real-time dynamically tuning an impedance match between an antenna coil and a signal generator, the method comprising:
Example 93. The method of Example 92, further comprising:
Example 94. A real-time tuning network configured to dynamically tune an impedance match between a signal generator and an antenna, the real-time tuning network comprising:
Example 95. The real-time tuning network of Example 94, wherein the real-time tuning discriminator includes:
Example 96. The real-time tuning network of Example 95, wherein the real-time tuning network further includes a power detector configured to detect at least one of the energizing signal current or the energizing signal voltage.
Example 97. The real-time tuning network of Example 95, wherein the phase compensation network includes:
Example 98. The real-time tuning network of Example 94, wherein the magnitude compensation network includes:
Example 99. The real-time tuning network of Example 95, wherein the coil antenna includes:
Example 100. The real-time tuning network of Example 98, wherein the tuning network is disposed between the primary coil and the signal generator,
Example 101. A system for dynamically configuring a secondary air-core coupled coil and exciting magnetic fields, the system comprising:
Example 102. The system of Example 101, wherein the coil antenna includes:
Example 103. The system of Example 102, wherein the coil antenna further includes a coil tuning network configured to tune at least one of a quality factor “Q” or an operating frequency of the primary coil.
Example 104. The system of Example 103, wherein tuning network includes:
Example 105. The system of Example 104, wherein tuning network further includes a power detection network configured to detect a power level from the energizing signal.
Example 106. The system of Example 105, wherein the instructions when executed further cause the system to:
Example 107. The system of Example 102, wherein the coil antenna further includes a termination network configured to enable or disable discrete secondary coils of the coil array.
Example 108. The system of Example 107, wherein the termination network includes:
Example 109. The system of Example 102, wherein the secondary coil is a configurable air-core coupled secondary coil, including a plurality of configurable secondary coil sections, the configurable air-core coupled secondary coil having a plurality of secondary coil configurations.
Example 110. The system of Example 109, wherein the coil antenna further includes a steering network configured to enable at least one of the plurality of secondary coil configurations.
Example 111. The system of Example 101, further including a surgical table, wherein the coil antenna is embedded into the surgical table.
Example 112. The system of Example 102, wherein the coil array includes a first coil and a second coil,
Example 113. The system of Example 112, wherein the first coil of the coil array is energized with the first current in at least one of a clockwise direction or a counter-clockwise direction, and
Example 114. A coil antenna, comprising:
Example 115. The coil antenna of Example 114, wherein the coil antenna further includes a coil tuning network configured to tune at least one of a quality factor “Q” or an operating frequency of each primary coil.
Example 116. The coil antenna of Example 114, wherein tuning network includes:
Example 117. The coil antenna of Example 114, wherein the coil antenna further includes a termination network configured to enable or disable discrete secondary coils of the coil array.
Example 118. The coil antenna of Example 117, wherein the termination network includes:
Example 119. The coil antenna of Example 114, wherein the secondary coil is a configurable air-core coupled secondary coil, including a plurality of configurable secondary coil sections, the configurable air-core coupled secondary coil having a plurality of secondary coil configurations.
Example 120. A method for interrogation and detection of surgical implements within a patient's body, the method comprising:
While aspects of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular aspects. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.
The present application is a U.S. National Stage Application filed under 35 U.S.C. § 371(a) of International Patent Application No. PCT/US2022/013482, filed on Jan. 26, 2022, which claims benefit of and priority to each of U.S. Provisional Patent Application Nos. 63/157,044 filed on Mar. 5, 2021, 63/157,050 filed on Mar. 5, 2021, 63/157,054 filed on Mar. 5, 2021, 63/157,058 filed on Mar. 5, 2021, 63/157,063 filed on Mar. 5, 2021 and 63/157,065 filed on Mar. 5, 2021. The entire disclosures of the foregoing applications are incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/013842 | 1/26/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63157044 | Mar 2021 | US | |
| 63157050 | Mar 2021 | US | |
| 63157054 | Mar 2021 | US | |
| 63157058 | Mar 2021 | US | |
| 63157063 | Mar 2021 | US | |
| 63157065 | Mar 2021 | US |
