# US 8,542,017 B2 · System and method for measuring the shape of an organ of a patient using a magnetic induction radio sensor integrated in a stretchable strap > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,017 B2 - Document ID: US8542017B2 - Status: Granted - Kind: B2 - Application number: 12/643,985 - Filed: 2009-12-21 - Published: 2011-06-23 - Granted: 2013-09-24 - Earliest claimed: 2009-12-21 - Assignees: NXP B.V. - Applicants: Steven Aerts - Inventors: Steven Aerts - Web page: https://patentgrep.com/patent/US8542017B2 ## CPC - G01B 7/28: for measuring contours or curvatures - A61B 5/05: Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves (measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24) - A61B 5/0806: {by whole-body plethysmography} - A61B 5/1135: {by monitoring thoracic expansion} - A61B 2560/0219: of externally powered implanted units - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract A system and method for measuring the shape of an object using a magnetic induction radio sensor involves at least partially enclosing the object with a magnetic loop antenna of the magnetic induction radio sensor, where the inductance of the magnetic loop antenna depends on the shape of the object, and providing a particular capacitance at an antenna matching circuit coupled to the magnetic loop antenna in response to the inductance of the magnetic loop antenna such that the magnetic loop antenna and the antenna matching circuit form a resonant circuit and the resonant circuit has a fixed resonant frequency, where the particular capacitance is used to measure the shape of the object. ## Claims ### Claim 1 A magnetic induction radio sensor configured for measuring the shape of an object, the magnetic induction radio sensor comprising: a magnetic loop antenna configured to at least partially enclose the object, wherein the inductance of the magnetic loop antenna depends on the shape of the object, wherein the magnetic loop antenna is configured to deform as a result of expansion and/or contraction of the object; an antenna matching circuit coupled to the magnetic loop antenna, wherein the antenna matching circuit comprises an adjustable capacitance module configured to provide a particular capacitance such that the magnetic loop antenna and the antenna matching circuit form a resonant circuit and the resonant circuit has a fixed resonant frequency; and a measuring unit configured to generate a measurement value using the particular capacitance of the adjustable capacitance module, the measurement value representing a measurement of the shape of the object, wherein the object is an organ of a patient, and wherein the magnetic loop antenna is integrated in a stretchable strap that at least partially encloses the organ of the patient. ### Claim 2 (depends on 1) The magnetic induction radio sensor of claim 1, wherein the adjustable capacitance module comprises an array of switchable capacitors in order to provide the particular capacitance. ### Claim 3 (depends on 2) The magnetic induction radio sensor of claim 2, wherein the array of switchable capacitors comprises capacitor branches that are connected in parallel with the magnetic loop antenna, and wherein each of the capacitor branches comprises a switch and a capacitor. ### Claim 4 (depends on 3) The magnetic induction radio sensor of claim 3, wherein capacitances of the capacitors in the capacitor branches have a numeric relationship of factors of two. ### Claim 5 (depends on 2) The magnetic induction radio sensor of claim 2, wherein capacitances of the capacitors in the capacitor branches are equal. ### Claim 6 (depends on 1) The magnetic induction radio sensor of claim 1, comprising multiple magnetic loop antennas configured to at least partially enclose the object, wherein the inductances of the magnetic loop antennas depend on the shape of the object, the magnetic induction radio sensor further comprising an array of switches configured for selecting the magnetic loop antennas. ### Claim 7 (depends on 1) The magnetic induction radio sensor of claim 1 further comprising a transmitter configured to transmit the generated measurement value to a remote device using the magnetic loop antenna. ### Claim 8 (depends on 7) The magnetic induction radio sensor of claim 7 further comprising a scheduling unit configured to repetitively schedule measurement of the shape of the object and transmission of the generated measurement value to the remote device according to predefined slots in a time division multiplexing scheme. ### Claim 9 (depends on 8) The magnetic induction radio sensor of claim 8, wherein the scheduling unit is further configured to schedule the measurement of the shape of the object after reception of a synchronization word from the remote device. ### Claim 10 (depends on 1) The magnetic induction radio sensor of claim 1 further comprising: an inductive charging circuit; and a rechargeable battery, wherein the rechargeable battery is charged when the magnetic loop antenna is placed in a magnetic field generated by the inductive charging circuit; or the magnetic loop antenna is further configured to receive direct inductive power such that the magnetic induction radio sensor of claim 1 is configured to operate without a battery using the received direct inductive power. ### Claim 11 (depends on 1) The magnetic induction radio sensor of claim 1 further comprising contact electrodes integrated in the stretchable strap and configured to measure bio-potentials of the patient. ### Claim 12 (depends on 11) The magnetic induction radio sensor of claim 11, wherein the organ is a lung of the patient, and wherein the stretchable strap wraps around the chest and/or abdomen of the patient in order to measure expansion and/or contraction of the torso of the patient to measure respiration of the patient. ### Claim 13 (depends on 11) The magnetic induction radio sensor of claim 11, wherein the organ is a limb of the patient, and wherein the stretchable strap wraps around the limb of the patient in order to measure expansion and/or contraction of muscles of the limb. ### Claim 14 A method of measuring the shape of an object using a magnetic induction radio sensor, the method comprising: at least partially enclosing the object with a magnetic loop antenna of the magnetic induction radio sensor, wherein the inductance of the magnetic loop antenna depends on the shape of the object; providing a particular capacitance at an antenna matching circuit coupled to the magnetic loop antenna such that the magnetic loop antenna and the antenna matching circuit form a resonant circuit and the resonant circuit has a fixed resonant frequency; and generating a measurement value using the particular capacitance, the measurement value representing a measurement of the shape of the object, wherein the object is an organ of a patient and wherein the magnetic loop antenna is integrated in a stretchable strap that at least partially encloses the organ of the patient. ### Claim 15 (depends on 14) The method of claim 14 further comprising adjusting the particular capacitance in response to a deformation of the magnetic loop antenna as a result of expansion and/or contraction of the object such that the resonant circuit still has the fixed resonant frequency. ### Claim 16 (depends on 15) The method of claim 15, wherein the providing the particular capacitance comprises providing the particular capacitance using an array of switchable capacitors, wherein the array of switchable capacitors comprises capacitor branches that are connected in parallel with the magnetic loop antenna, and wherein each of the capacitor branches comprises a switch and a capacitor. ### Claim 17 A magnetic induction radio system configured for measuring the shape of an object, the magnetic induction radio system comprising: a magnetic induction radio sensor comprising: a magnetic loop antenna configured to at least partially enclose the object, wherein the inductance of the magnetic loop antenna depends on the shape of the object; an antenna matching circuit coupled to the magnetic loop antenna, wherein the antenna matching circuit comprises an adjustable capacitance module configured to provide a particular capacitance such that the magnetic loop antenna and the antenna matching circuit form a resonant circuit and the resonant circuit has a fixed resonant frequency; a measuring unit configured to generate a measurement value using the particular capacitance of the adjustable capacitance module, the measurement value representing a measurement of the shape of the object; and a transmitter configured to transmit the generated measurement value using the magnetic loop antenna; and a remote device configured to receive the transmitted measurement value from the transmitter of the magnetic induction radio sensor, wherein the object is an organ of a patient and wherein the magnetic loop antenna is integrated in a stretchable strap that at least partially encloses the organ of the patient. ### Claim 18 (depends on 17) The magnetic induction radio system of claim 17, wherein the adjustable capacitance module comprises an array of switchable capacitors in order to provide the particular capacitance.