Coil System and Method for Obtaining Volumetric Physiological Measurements

Abstract

A coil device is provided having a member adapted to extend around and conform to an outer surface of a subject and a conductor adapted to extend only once around a first portion of the subject. The coil device can be positioned about the subject in order to measure a volume of the subject. When placed about the subject in the presence of a relatively homogeneous magnetic field, the conductor can generate a signal indicative of a volume of the first portion of the subject. The coil device may also include two or more conductors separately generating signals indicating volumes of two or more corresponding portions of the subject. In some cases the coil device includes associated authorization data that can limit use of the coil device. Systems and methods incorporating the coil device are also provided.

1 . A coil device for use in measuring a volume of a subject's abdomen and/or chest, the coil device comprising:
 a first member adapted to extend around an outer surface of a first portion of the subject's abdomen and/or chest and conform to the outer surface despite changes in a contour of the outer surface,   the first member comprising a first conductor adapted to extend only once around the subject's abdomen and/or chest,   the first conductor adapted to generate, in the presence of a relatively homogeneous magnetic field produced by an energized electromagnet, a signal indicative of a volume of the first portion of the subject's abdomen and/or chest.   
     
     
         2 . The coil device of  claim 1 , wherein the first member comprises
 (i) first and second opposed edges, with the first edge being nearer the subject's head, and   (ii) first and second opposed end sections adapted to be positioned proximate to one another and secured to conform the first member to the outer surface, and wherein   the first conductor comprises a plurality of angled segments extending between the first and second opposed edges at multiple points between the first and second opposed end sections.   
     
     
         3 . The coil device of  claim 2 , wherein the plurality of angled segments form a zigzag configuration. 
     
     
         4 . The coil device of  claim 2 , wherein a cross-sectional area of the subject's abdomen and/or chest varies between the first and second opposed edges of the first member and the signal generated by the first conductor corresponds to an average cross-sectional area of the first portion of the subject's abdomen and/or chest. 
     
     
         5 . The coil device of  claim 4 , wherein the signal generated by the first conductor is generally proportional to the volume of the first portion of the subject's abdomen and/or chest, with an approximate proportionality constant of a distance between the first and second opposed edges of the first member. 
     
     
         6 . The coil device of  claim 1 , further comprising a second member adapted to extend around an outer surface of a second portion of the subject's abdomen and/or chest and conform to the outer surface of the second portion despite changes in a contour of the outer surface of the second portion, the second member comprising a second conductor adapted to extend only once around the subject's abdomen and/or chest, the second conductor adapted to generate, in the presence of a relatively homogeneous magnetic field produced by an energized electromagnet, a signal indicative of a volume of the second portion of the subject's abdomen and/or chest. 
     
     
         7 . The coil device of  claim 6 , wherein the first portion is at least part of the subject's abdomen and not part of the subject's chest, and wherein the second portion is at least part of the subject's chest and not part of the subject's abdomen. 
     
     
         8 . The coil device of  claim 1 , further comprising an elastic substrate carrying the first member. 
     
     
         9 . The coil device of  claim 8 , further comprising a second member carried by the elastic substrate, the second member adapted to extend around an outer surface of a second portion of the subject's abdomen and/or chest and conform to the outer surface of the second portion despite changes in a contour of the outer surface of the second portion, the second member comprising a second conductor adapted to extend only once around the subject's abdomen and/or chest, the second conductor adapted to generate, in the presence of a relatively homogeneous magnetic field produced by an energized electromagnet, a signal indicative of a volume of the second portion of the subject's abdomen and/or chest. 
     
     
         10 . The coil device of  claim 9 , wherein the first portion is at least part of the subject's abdomen and not part of the subject's chest, and wherein the second portion is at least part of the subject's chest and not part of the subject's abdomen. 
     
     
         11 . The coil device of  claim 9 , wherein the elastic substrate comprises
 (i) first and second opposed edges, with the first edge being nearer the subject's head, and   (ii) first and second opposed end sections adapted to be positioned proximate to one another and secured to conform the elastic substrate to the outer surface, wherein the first and second conductors extend between the first and second end sections, and further comprising a common third conductor extending between the first and second end sections, wherein the first and second conductors are electrically coupled to the third conductor proximate the second end section of the elastic substrate.   
     
     
         12 . The coil device of  claim 11 , wherein the first, second, and third conductors exit the substrate at a common area proximate the first end section of the substrate. 
     
     
         13 . The coil device of  claim 11 , wherein the third conductor is adapted to extend around an outer surface of a third portion of the subject, the third portion having a relatively constant volume. 
     
     
         14 . The coil device of  claim 13 , wherein the third conductor is carried by the elastic substrate adjacent to the second edge of the elastic substrate. 
     
     
         15 . The coil device of  claim 8 , wherein the first conductor is plastic welded, glued, or stitched to the elastic substrate. 
     
     
         16 . The coil device of  claim 8 , wherein the elastic substrate comprises
 (i) first and second opposed edges, with the first edge being nearer the subject's head, and   (ii) first and second opposed end sections adapted to be positioned proximate to one another and secured to conform the elastic substrate to the outer surface, wherein the first and second end sections are secured by a fastener selected from the group consisting of hook-and-loop fasteners, adhesive tape, buttons, staples, and zippers.   
     
     
         17 . The coil device of  claim 1 , further comprising an elastic substrate carrying the first member, wherein the elastic substrate comprises a sleeve adapted to fit around the first portion of the subject's abdomen and/or chest. 
     
     
         18 . The coil device of  claim 1 , further comprising an electronic memory storing authorization data for determining whether use of the coil device is authorized. 
     
     
         19 . A coil device for use in measuring a volume of a subject's abdomen and/or chest, the coil device comprising:
 a first member adapted to extend around an outer surface of a first portion of the subject's abdomen and/or chest, the first member comprising
 (a) first conforming means for conforming the first member to the outer surface of the first portion despite changes in a contour of the outer surface of the first portion, and 
 (b) first conducting means for generating, in the presence of a relatively homogeneous magnetic field produced by an energized electromagnet, a signal indicative of a volume of the first portion of the subject's abdomen and/or chest. 
   
     
     
         20 . The coil device of  claim 19 , wherein the first conducting means comprises a single conductor adapted to extend only once around the subject's abdomen and/or chest. 
     
     
         21 . The coil device of  claim 20 , wherein the first conforming means comprises an elastic substrate carrying the first member. 
     
     
         22 . The coil device of  claim 19 , further comprising:
 a second member adapted to extend around an outer surface of a second portion of the subject's abdomen and/or chest, the second member comprising
 (a) second conforming means for conforming the second member to the outer surface of the second portion despite changes in a contour of the outer surface of the second portion, and 
 (b) second conducting means for generating, in the presence of a relatively homogeneous magnetic field produced by an energized electromagnet, a signal indicative of a volume of the second portion of the subject's abdomen and/or chest. 
   
     
     
         23 . The coil device of  claim 22 , wherein the first portion is at least part of the subject's abdomen and not part of the subject's chest, and wherein the second portion is at least part of the subject's chest and not part of the subject's abdomen. 
     
     
         24 . The coil device of  claim 22 , further comprising an elastic substrate carrying the first and second members, wherein both the first and second conforming means comprise the elastic substrate. 
     
     
         25 . The coil device of  claim 24 , wherein the elastic substrate comprises
 (i) first and second opposed edges, with the first edge being nearer the subject's head, and   (ii) first and second opposed end sections adapted to be positioned proximate to one another and secured to conform the elastic substrate to the outer surface, wherein the first and second conducting means extend between the first and second end sections, and further comprising a common third conducting means extending between the first and second end sections, wherein the first and second conducting means are electrically coupled to the third conducting means proximate the second end section of the elastic substrate.   
     
     
         26 . The coil device of  claim 25 , further comprising connecting means, wherein the first, second, and third conducting means are electrically coupled to the connecting means, and wherein the first, second, and third conducting means exit the substrate at a common area proximate the first end section of the substrate. 
     
     
         27 . The coil device of  claim 19 , further comprising authorization means for determining whether use of the coil device is authorized. 
     
     
         28 . The coil device of  claim 27 , further comprising an electronic memory, wherein the authorization means comprises authorization data stored in the electronic memory. 
     
     
         29 . A method for measuring a volume of a subject's abdomen and/or chest, comprising:
 providing a coil device comprising a first member, the first member comprising a first conductor;   extending the first member around an outer surface of a first portion of the subject's abdomen and/or chest, thereby conforming the first member to the outer surface despite changes in a contour of the outer surface and extending the first conductor only once around the subject's abdomen and/or chest;   generating with an electromagnet a relatively homogeneous magnetic field throughout a predefined spatial volume;   positioning the first portion of the subject's abdomen and/or chest within the spatial volume;   measuring a signal induced in the first conductor by the relatively homogeneous magnetic field; and   estimating a volume of the first portion of the subject's abdomen and/or chest based on the signal measured in the first conductor.   
     
     
         30 . The method of  claim 29 , wherein the coil device further comprises a second member comprising a second conductor, and further comprising:
 extending the second member around an outer surface of a second portion of the subject's abdomen and/or chest, thereby conforming the second member to the outer surface of the second portion despite changes in a contour of the outer surface of the second portion and extending the second conductor only once around the subject's abdomen and/or chest;   positioning the second portion of the subject's abdomen and/or chest within the spatial volume;   measuring a signal induced in the second conductor by the relatively homogeneous magnetic field; and   estimating a volume of the second portion of the subject's abdomen and/or chest based on the signal measured in the second conductor.   
     
     
         31 . The method of  claim 30 , wherein the first portion is at least part of the subject's abdomen and not part of the subject's chest, and wherein the second portion is at least part of the subject's chest and not part of the subject's abdomen. 
     
     
         32 . The method of  claim 29 , wherein the signal measured in the first conductor corresponds to an average cross-sectional area of the first portion of the subject's abdomen and/or chest, wherein the first member has first and second opposed edges, with the first edge being nearer the subject's head, and further wherein estimating the volume of the first portion comprises multiplying the average cross-sectional area by a distance between the first and second opposed edges of the first member. 
     
     
         33 . The method of  claim 29 , further comprising enabling use of the coil device only if use of the coil device is authorized. 
     
     
         34 . A method for measuring a volume of a subject's abdomen and/or chest, comprising:
 providing a coil device comprising an electronic memory storing authorization data;   positioning the coil device around an outer surface of a first portion of the subject's abdomen and/or chest;   reading the authorization data from the electronic memory;   determining from the authorization data whether use of the coil device is authorized;   generating with an electromagnet a relatively homogeneous magnetic field throughout a predefined spatial volume;   positioning the first portion of the subject's abdomen and/or chest within the spatial volume;   and   if use of the coil device is authorized, estimating a volume of the first portion of the subject's abdomen and/or chest, based on a signal induced in the first conductor by the relatively homogeneous magnetic field.   
     
     
         35 . The method of  claim 34 , further comprising measuring the signal induced in the first conductor only if use of the coil device is authorized. 
     
     
         36 . The method of  claim 34 , wherein the coil device further comprises a first member comprising a first conductor, and wherein positioning the coil device comprises extending the first member around the outer surface of the first portion of the subject's abdomen and/or chest, thereby conforming the first member to the outer surface despite changes in a contour of the outer surface and extending the first conductor only once around the subject's abdomen and/or chest. 
     
     
         37 . The method of  claim 34 , wherein determining whether use of the coil device is authorized comprises determining whether the coil device has exceeded a maximum number of authorized uses. 
     
     
         38 . The method of  claim 37 , wherein the authorization data comprises a maximum count corresponding to the maximum number of authorized uses and a current count corresponding to an actual number of uses of the coil device, and wherein determining whether use of the coil device is authorized comprises comparing the current count with the maximum count. 
     
     
         39 . The method of  claim 38 , further comprising incrementing the current count after a use of the coil device. 
     
     
         40 . The method of  claim 34 , further comprising assigning a subject identifier to the subject and storing the subject identifier in the electronic memory as a stored identifier, and wherein determining from the authorization data whether use of the coil device is authorized comprises comparing the subject identifier with the stored identifier. 
     
     
         41 . The method of  claim 34 , wherein the electronic memory further comprises a proportionality constant corresponding to the coil device, and further comprising estimating the volume of the first portion of the subject's abdomen and/or chest based on the induced signal and the proportionality constant. 
     
     
         42 . A system for measuring a volume of a subject's abdomen and/or chest, comprising:
 an electromagnet adapted to generate a relatively homogeneous magnetic field within a predefined spatial volume;   a coil device comprising an electronic memory storing authorization data, the coil device adapted to conform to an outer surface of a first portion of the subject's abdomen and/or chest and generate, in the presence of the relatively homogeneous magnetic field produced by the electromagnet, a signal indicative of a volume of the first portion of the subject's abdomen and/or chest; and   a control system electrically coupled to the coil device, the control system adapted to read the authorization data from the electronic memory, determine from the authorization data whether use of the coil device is authorized, measure the signal generated by the first conductor, and if use of the coil device is authorized, estimate the volume of the first portion of the subject based on the signal received from the first conductor.   
     
     
         43 . The system of  claim 42 , wherein the coil device further comprises a first member adapted to extend around the outer surface and conform to the outer surface despite changes in a contour of the outer surface, the first member comprising a first conductor adapted to extend only once around the subject's abdomen and/or chest. 
     
     
         44 . The system of  claim 42 , wherein the control system measures the signal generated by the coil device only if use of the coil device is authorized. 
     
     
         45 . The system of  claim 42 , wherein the authorization data comprises a maximum count corresponding to a maximum number of authorized uses of the coil device and a current count corresponding to an actual number of uses of the coil device, and wherein control system is adapted to compare the current count with the maximum count. 
     
     
         46 . The system of  claim 45 , wherein the control system is adapted to increment the current count after a use of the coil device. 
     
     
         47 . The system of  claim 42 , wherein the authorization data comprises a stored identifier and the control system is adapted to compare the stored identifier with a subject identifier assigned to the subject. 
     
     
         48 . The system of  claim 42 , wherein the electronic memory further comprises a proportionality constant corresponding to the coil device, and wherein the control system is adapted to estimate the volume of the first portion of the subject additionally based on the proportionality constant.