Abstract:
A transducer for noninvasively determining an internal temperature of a location of interest in a body of a subject may be configured to receive native temperature signals originating from the location of interest without substantially receiving interfering signals. Such a transducer may include one or more shielding features for preventing interference. In addition, such a transducer may include a dielectric cavity configured or positioned to increase the native temperature signals sensed, or received, by the antenna. A transducer may be configured to multiplex signals that are indicative of a temperature of a location of interest within the body of a subject and reference temperature signals. Such a transducer may include a connector that facilitates the communication of a multiplexed signal, such as a connector for a coaxial cable. The connector of a transducer may be configured to swivel relative to an end of a cable that has been coupled thereto. Systems including such a transducer are also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    A claim for the benefit of priority to the Sep. 28, 2013 filing date of U.S. Provisional Patent Application No. 61/883,980, titled APPARATUSES FOR NON-INVASIVELY SENSING INTERNAL TEMPERATURE (“the &#39;980 Provisional Application”), is hereby made pursuant to 35 U.S.C. §119(e). The entire disclosure of the &#39;980 Application is hereby incorporated herein. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates generally to apparatuses for determining a temperature of at least a portion of a body of a subject and, more specifically, to apparatuses for noninvasively determining body temperature. More specifically, the disclosed subject matter relates to apparatuses for noninvasively determining a temperature within a body of a subject, such as brain temperature. 
       SUMMARY 
       [0003]    An apparatus according to this disclosure, which is also referred to as a “transducer,” noninvasively senses an indicator of a temperature within a body of a subject; i.e., an indicator of an internal temperature, or a “native temperature signal.” The transducer may be configured to be positioned against a portion of the body of the subject that is adjacent to or near a location for which a temperature measurement is to be obtained, or a “location of interest” within the subject&#39;s body. To enable such noninvasive sensing, the transducer may be configured to be positioned against or adjacent to an exterior surface of the subject&#39;s body, or against or adjacent to a portion of the subject&#39;s body that is readily accessible from the exterior of the subject&#39;s body. 
         [0004]    A transducer for noninvasively sensing an indicator of internal temperature may be configured as a low profile apparatus with a sensor that is configured to receive the indicator of internal temperature from the location of interest. A contact side of the transducer is the side of the transducer that is configured to face the location of interest, while an outside of the transducer is configured to face away from the location of interest. 
         [0005]    The contact side of the transducer may comprise a receiving aperture, through which an indicator of internal temperature may pass, or be transmitted, to the sensor. The receiving aperture may comprise an opening in the contact side of the transducer or it may comprise a solid material through which the indicator of internal temperature may pass. 
         [0006]    The transducer may be configured to receive the indicator of internal temperature from the location of interest without substantial interference. In this regard, the transducer may include one or more shielding features for preventing interference between the indicator of internal temperature and external factors that compete with the indicator, which external factors are also referred to herein as “noise” and as “interference.” In a specific, but non-limiting embodiment, the sensor of the transducer may comprise an antenna for receiving microwaves, which are an indicator of temperature within the body of the subject, that originate from the location of interest and the one or more shielding features be configured to prevent microwaves from other sources from reaching the sensor. More specifically, the one or more shielding features may comprise a conductive coating or conductive film. The one or more shielding features may be located on portions of the transducer that will face away from the body of the subject or, even more specifically, away from the location of interest, upon positioning the transducer in a manner that will enable it to sense microwaves that originate from the location of interest. Optionally, one or more shielding features may be located on portions of the contact side of the transducer; for example, around a periphery of the contact side. 
         [0007]    The transducer may include a dielectric cavity between the one or more shielding features and a back side of the sensor. The dielectric cavity may prevent electrical shorting between the one or more shielding features and the sensor. Accordingly, the dielectric cavity may be formed from an electrically insulative, or dielectric, material (i.e., a material with a low dielectric constant, K), including solid materials, porous materials and gases. In a specific, but non-limiting embodiment, the dielectric cavity may have a thickness (i.e., the distance between the back side of the sensor and an inner surface of a shielding feature, of about fifty thousandths (0.050) of an inch (e.g., 0.040 inch, 0.060 inch, etc.). The dielectric cavity may function in conjunction with one or more shielding features to prevent noise or interference from reaching the back side of the sensor and, thus, the back side of the antenna. 
         [0008]    In some embodiments, a transducer may include a communication element for transmitting internal temperature signals, which are also referred to herein as “intermediate temperature signals,” from the sensor to a monitor (e.g., a radiometer in embodiments where the sensor is configured to receive microwaves or other frequencies of electromagnetic radiation, etc). The communication element may comprise a connector for a cable. In some embodiments, the communication element may be configured to enable one or both of the transducer and an end of the cable to swivel relative to one another, which may accommodate movement by a subject while sensing an indicator of an internal temperature of the subject. In some embodiments, a coaxial cable connector (and a coaxial cable) may enable an end of a cable to swivel relative to the transducer while intermediate temperature signals are being transmitted from the sensor of the transducer to a separate monitor. 
         [0009]    The transducer may also include a reference temperature sensor. Such a transducer may be configured to multiplex intermediate temperature signals from the sensor and reference temperature signals from the reference temperature sensor. The multiplexed signals may be conveyed through a communication element, such as a cable connector, of the transducer, to a complementary communication element of a monitor, which may be configured to demultiplex the signals (if they were multiplexed by the transducer) and process signals from the transducer. 
         [0010]    Other aspects, as well as features and advantages of various aspects, of the disclosed subject matter will become apparent to those of ordinary skill in the art through consideration of the ensuing description, the accompanying drawings and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    In the drawings: 
           [0012]      FIGS. 1A and 1B  illustrates an embodiment of an apparatus, or transducer, for non-invasively sensing an internal temperature of a potion of a body of a subject; 
           [0013]      FIG. 2  is a cross-sectional representation of the embodiment of transducer shown in  FIGS. 1A and 1B ; 
           [0014]      FIG. 3  depicts an embodiment of use of a transducer according to this disclosure; and 
           [0015]      FIG. 4  is a schematic representation of an embodiment of an electrical circuit of an embodiment of transducer according to this disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    As shown in  FIGS. 1A through 3 , a transducer  10  according to this disclosure comprises a low profile apparatus that is configured to noninvasively sense an indicator of an internal temperature within a portion of a body of a subject. Thus, the transducer  10  may include a sensor  20  and a communication element  50  for conveying signals from the sensor  20  to an external monitor  60  (see  FIG. 3 ). In addition, a housing  30  of the transducer  10  may carry the sensor  20 . 
         [0017]    The transducer  10  includes a contact side  12  and an outside  16 . The contact side  12  of the transducer  10  may be configured to face a location of interest L ( FIG. 3 ) within the body B of a subject, while the outside  16  of the transducer  10  may be configured to face away from the location of interest L. At its contact side  12 , the transducer  10  may include a receiving aperture  13 , through which an indicator of internal temperature, or a native temperature signal S N , may pass, or be transmitted, to the sensor  20 . The receiving aperture  13  may comprise an opening in the contact side  12  of the transducer  10  or a solid material (e.g., one or more of a dielectric material, an adhesive material, etc.). 
         [0018]    The sensor  20 , which is depicted by  FIG. 2 , is configured to receive one or more native temperature signals S N  from the location of interest L within the body B of the subject. In some embodiments, the sensor  20  may include one or more antennas from receiving native temperature signals S N  that comprise electromagnetic radiation in the so-called “microwave” portion of the electromagnetic spectrum. Without limitation, in a specific embodiment, the range of frequencies of microwave radiation that may be received by the sensor  20  may include native temperature signals S N  having frequencies in the range of about 4 GHz±200 MHz. Specific embodiments of such a sensor  20 , which comprise electrically conductive features of a printed circuit board (PCB), are disclosed by PCT International Publication No. WO 2013/090047 A2 of Meridian Medical Systems, LLC, which was published on Jun. 20, 2013, the entire disclosure of which is hereby incorporated herein. Such a sensor  20  may receive, and sense, signals that impinge either side—a front side  22  or a back side  26 —thereof. 
         [0019]    The front side  22  of the sensor faces the contact side  12  of the transducer  10  and, thus, is located adjacent to the receiving aperture  13 . The back side  26  of the sensor  20  faces the opposite direction, toward the outside  16  of the transducer  10 . When the transducer  10  is positioned on the body B of a subject, the front side  22  of the sensor  20  faces the location of interest L, while its back side  26  faces away from the location of interest L. 
         [0020]    In some embodiments, a dielectric cavity  28  may be located over, or even directly adjacent to, the back side  26  of the sensor  20 . The dielectric cavity  28  may provide electrical insulation over the back side  26 . Without limitation, the dielectric cavity  28  may comprise a dielectric material, which, in some embodiments, may comprise a foam or otherwise include voids (e.g., microspheres, microcapsules, etc.; an open-celled material; a close-celled material; etc.). Alternatively, the dielectric cavity  28  may comprise a void over the back side  26 . Such a void may include a gas (e.g., an inert gas, such as argon; nitrogen; etc.), a mixture of gases (e.g., air, etc.) or a vacuum. 
         [0021]    One or more shielding features  36  of the transducer  10  may be located over the back side  26  of the sensor  20  to prevent interfering signals S X  (e.g., microwaves, etc.) from sources other than the location of interest L from reaching the back side  26  of the sensor  20  and, thus, from interfering with (e.g., appearing to the sensor  20  to be) native temperature signals S N  from the location of interest L. In embodiments where the transducer  10  includes a dielectric cavity  28 , the shielding feature(s)  36  may be positioned over the dielectric cavity  28  or, in embodiments where the dielectric cavity  28  comprises a void, even define a boundary of the dielectric cavity  28 . 
         [0022]    In various embodiments, the shielding feature(s)  36  may comprise a low resistance electrically conductive material, such as a metal. Such a shielding feature  36  may comprise a film (e.g., plating, a deposited film, etc.), a foil or another structure or group of structures. In some embodiments, shielding features  36  may also be positioned and/or configured to prevent the interfering signals S X  from reaching the front side  22  of the sensor  20 . 
         [0023]    The receiving aperture  13 , the sensor  20 , the dielectric cavity  28  (if any) and the shielding features  36  may be defined by and/or carried by a housing  30  of the transducer  10 . With continued reference to  FIG. 2 , the transducer  10  may include a housing  30  that carries the sensor  20  and orients and positions the sensor  20  in a manner that will enable the sensor  20  to receive, or sense, native temperature signals S N  originating from a location of interest L within the body B of a subject ( FIG. 3 ). 
         [0024]    In the illustrated embodiment, the housing  30  comprises a rigid structure (e.g., a structure that is molded, pressed, machined, etc.). Alternatively, the housing  30  may comprise a conformal coating (e.g., a film, such as a shrink-wrap film, a deposited polymeric coating, etc.). The housing  30  may define the outside  16  of the transducer  10 , toward which the back side  26  of the sensor  20  is oriented. The housing  30  may carry the sensor  20  in a manner that orients the front side  22  of the sensor  20  toward the receiving aperture  13  and the contact side  12  of the transducer  10 . In embodiments where a dielectric cavity  28  is located adjacent to, or over, the back side  26  of the sensor  20  and between the back side  26  of the sensor  20  and the outside  16  of the transducer  10 , the housing  30  and the back side  26  of the sensor  20  may define the boundaries  29  of the dielectric cavity  28 . In some embodiments, a housing  30  may also define at least a portion of the contact side  12  of the transducer  10 . As an example, the housing  30  may define at least a portion of the receiving aperture  13 . 
         [0025]    The housing  30  also carries one or more shielding features  36  of the transducer  10 . In the illustrated embodiment, the shielding feature(s)  36  cover(s) the back side  26  of the sensor  20 , as well as a periphery  24  of the sensor  20  and a periphery  14  of the receiving aperture  13 . As illustrated, the shielding feature(s)  36  may be carried by an interior surface  32  of the housing  30 . As an alternative, or in addition, to carrying one or more shielding features  36  on its interior surface  32 , the housing  30  may carry one or more shielding features  36  on its exterior surface  34 . 
         [0026]    The transducer  10  may also include an adhesive material  38  on at least portions of its contact side  12 . The adhesive material  38  may be located adjacent to a periphery  12   p  of the contact side  12  of the transducer  10  and surround a more centrally located portion  12   c  of the contact side  12 . Alternatively, the adhesive material  38  may comprise or substantially cover the contact side  12  of the transducer  10 . In such an embodiment, the adhesive material  38  may form a part of or all of the receiving aperture  13  of the transducer  10 . In any event, the adhesive material  38  may prevent interfering signals S X  from passing between the contact side  12  of the transducer  10  and a surface against which the contact side  12  is positioned and into the receiving aperture  13  of the transducer  10 . The adhesive material  38  may be configured to secure the transducer  10  in place on or over the body of a subject. 
         [0027]    When a sensor  20  of a transducer  10  senses, or receives, native temperature signals S N , those signals may be converted to electrical signals, which are referred to herein as “intermediate temperature signals.” The transducer  10  may be configured to transmit the intermediate temperature signals to a separate, external monitor  60 . Accordingly, the transducer  10  may include a communication element  50 , which is in communication with the sensor  20  and is configured to communicate with a corresponding element of the external monitor  60 . The communication element  50  may be configured to couple with an end  56  of a cable  55  in a manner that enables the one or both of the end  56  and the communication element  50  to swivel relative to the other of the communication element  50  and the end  56  of the cable  55 . In some embodiments, the communication element  50  and the end  56  of the cable  50  may comprise coaxial connectors, as depicted by  FIGS. 1A through 3 . 
         [0028]    In some embodiments, the transducer  10  may also include a reference temperature sensor  45 . The reference temperature sensor  45  may be configured to obtain a measurement of a reference temperature, such as a temperature of skin at or adjacent to a location where the transducer  10  is positioned on the body B of a subject. In a specific, but non-limiting embodiment, the reference temperature sensor  45  may comprise a thermistor, a resistance temperature detector (RTD), a thermocouple, an infrared (IR) temperature sensor or the like. 
         [0029]    The transducer  10  may include one or more components (e.g., circuitry, etc.), which may be carried by the sensor  20  (e.g., by a circuit board that defines the sensor, etc.), configured to multiplex intermediate temperature signals and reference temperature signals from the reference temperature sensor  45 . Turning now to  FIG. 4 , a schematic representation of an embodiment of an electrical circuit that enables such multiplexing is depicted. Specifically,  FIG. 4  illustrates the sensor  20 , a capacitor  25  including a conductor in communication with sensor  20 , a reference temperature sensor  45  in communication with an opposite conductor of the capacitor  25 , and a communication element  50  (e.g., a cable connector, etc.) in series with the reference temperature sensor  45 . This arrangement may enable multiplexing of the intermediate temperature signal from the sensor  20  and the reference temperature signal from the reference temperature sensor  45 . 
         [0030]    With continued reference to  FIG. 4 , the communication element  50  of a transducer  10  may be configured to enable intermediate temperature signals from the sensor  20  to be communicated to a monitor  60 , as disclosed previously. Optionally, in embodiments where a transducer includes a reference temperature sensor  45 , the communication element  50  may also enable the communication of reference temperature signals to the monitor  60 . 
         [0031]    The monitor  60  may include a communication element  62  for receiving signals from the communication element  50  of the transducer  10 . Accordingly, the communication element  62  of the monitor  60  may be configured in a manner that complements a configuration of the communication element  50  of the transducer  10 . In a non-limiting example, where the communication element  50  comprises a coaxial cable connector and the cable  55  comprises a coaxial cable, the communication element  62  of the monitor  60  may also comprise a coaxial cable connector. 
         [0032]    Signals that are received by the communication element  62  of the monitor  60  are conducted to a first capacitor  64  and to an inductor  68 , which are in parallel with one another. Signals that cross the first capacitor  64  are conducted to one or more radiometers  66 , which convert each received signal to a voltage. Signals that pass through the inductor  68  are conducted to a thermistor output  70  or to a second capacitor  72 , which are in parallel with one another. The second capacitor  72  is connected to a ground  74 . This arrangement enables demultiplexing of the intermediate temperature signals from the reference temperature signals and, optionally, one or more other signals. More specifically, the first capacitor  64  ensures that only the intermediate temperature signal is conveyed to the radiometer(s)  66 , while the second capacitor  72  and ground  74  ensure that only the reference temperature signal is conveyed to the thermistor output  70 . 
         [0033]    The monitor  60  may be configured to process the signals in a manner that provides a desired output. 
         [0034]    Although the foregoing description sets forth many specifics, these should not be construed as limiting the scope of any of the claims, but merely as providing illustrations of some embodiments and variations of elements or features of the disclosed subject matter. Other embodiments of the disclosed subject matter may be devised which do not depart from the spirit or scope of any of the claims. Features from different embodiments may be employed in combination. Accordingly, the scope of each claim is limited only by its plain language and the legal equivalents thereto.