Remote magneto-elastic analyte, viscosity and temperature sensing apparatus and associated methods of sensing
First Claim
1. An analyte sensing apparatus for operative arrangement within a time-varying magnetic field, comprising:
- a sensor having an outer surface of a material that is chemically responsive to the analyte, said material being adhered to a base magnetostrictive element, said sensor having a magneto-elastic resonant frequency;
a receiver to measure a first and second value for magneto-elastic emission intensity of said sensor taken at, respectively, a first and second interrogation frequency; and
a unit to identify a change in mass of said sensor using a ratio of said first and second values.
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Abstract
An analyte, viscosity, or temperature sensing apparatus for operative arrangement within a time-varying magnetic field, including a sensor with an outer surface that is chemically, frictionally, or thermally responsive and adhered to a base magnetostrictive element, and a receiver to measure a first and second value for magneto-elastic emission intensity of the sensor taken at, respectively, a first and second interrogation frequency. A change in mass or a change in material stiffness of the sensor due to the responsiveness, the viscosity and mass density of a fluid therearound, or the temperature, can be identified. The receiver, alternatively, measures a plurality of successive values for magneto-elastic emission intensity of the sensor taken over an operating range of successive interrogation frequencies to identify a value for the sensor'"'"'s magneto-elastic resonant frequency (a fundamental frequency or harmonic thereof). Several sensors in an ordered array will provide a “package” of information.
150 Citations
30 Claims
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1. An analyte sensing apparatus for operative arrangement within a time-varying magnetic field, comprising:
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a sensor having an outer surface of a material that is chemically responsive to the analyte, said material being adhered to a base magnetostrictive element, said sensor having a magneto-elastic resonant frequency;
a receiver to measure a first and second value for magneto-elastic emission intensity of said sensor taken at, respectively, a first and second interrogation frequency; and
a unit to identify a change in mass of said sensor using a ratio of said first and second values. - View Dependent Claims (2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14)
said first interrogation frequency is less than said magneto-elastic resonant frequency by an interval, Δ
f, said second interrogation frequency is greater than said magneto-elastic resonant frequency by approximately said interval, Δ
f, said interval being a value between 0.001% and 40% of said magneto-elastic resonant frequency; and
said receiver is an electromagnetic pick-up coil, said magneto-elastic emission is an electromagnetic emission, and said magneto-elastic resonant frequency is a harmonic of a fundamental resonant frequency of said sensor.
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13. The apparatus of claim 12 wherein:
- said chemically responsive material is a chemically receptive polymer layer having a plurality of microspheres which is adhered over a substantial portion of said base magnetostrictive element;
said chemical responsiveness comprises swelling of said microspheres as a function of the analyte moisture content; and
said sensor is incorporated within an array of magnetostrictive elements comprising a viscosity sensing element.
- said chemically responsive material is a chemically receptive polymer layer having a plurality of microspheres which is adhered over a substantial portion of said base magnetostrictive element;
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14. The apparatus of claim 1 further comprising a second sensor having a second resonant frequency different from said magneto-elastic resonant frequency, said second sensor for sensing a viscosity of a fluid therearound;
- and wherein said receiver is used to measure a third and fourth value for magneto-elastic emission intensity of said second sensor taken at, respectively, a third and fourth interrogation frequency.
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7. An analyte sensing apparatus for operative arrangement within a time-varying magnetic field, comprising:
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a sensor having an outer surface of a material that is chemically responsive to the analyte, said material being adhered to a base magnetostrictive element, said sensor having a magneto-elastic resonant frequency;
a receiver to measure a first and second value for magneto-elastic emission intensity of said sensor taken at, respectively, a first and second interrogation frequency, and a unit to identify a change in material stiffness of said sensor using a ratio of said first and second values;
wherein said magneto-elastic resonance frequency is a harmonic of a fundamental resonant frequency of the sensor; and
a pre-correlation made between a series of emission intensity ratio values taken for said sensor and a corresponding series of material stiffness values is used for said identification of said change in material stiffness.
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15. An analyte sensing apparatus for operative arrangement within a time-varying magnetic field, comprising:
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a sensor having an outer surface of a material that is chemically responsive to the analyte, said material being adhered to a base magnetostrictive element;
a receiver to measure a plurality of successive values for magneto-elastic emission intensity of said sensor taken over an operating range of successive interrogation frequencies to identify a magneto-elastic resonant frequency value for said sensor; and
a unit to identify a change in mass of said sensor using said identified magneto-elastic resonant frequency value. - View Dependent Claims (16, 17, 18, 19, 20)
said magneto-elastic emission is an acoustic emission, and said receiver is an electroacoustic device containing a transducer;
said chemically responsive material is a polymer layer having swellable gel membrane complexes, said chemical responsiveness comprising diffusion of selected ion species of the analyte into said polymer layer to sense glucose concentration; and
a pre-correlation made between a series of acoustic resonant frequency values for said sensor and a corresponding series of mass change values for said sensor is used for said identification of said change in mass.
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19. The apparatus of claim 15 wherein said receiver is an electromagnetic pick-up coil, said magneto-elastic emission is an electromagnetic emission, said magnetostrictive element is elongated in shape, and further comprising, in proximity to said sensor, a magnetizable magnetically hard element for generating a DC bias field.
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20. The apparatus of claim 15 further comprising a second sensor for sensing temperature, both said sensors extending from a support member;
- said receiver to further measure a second plurality of successive values for magneto-elastic emission intensity of said second sensor taken over a second operating range of successive interrogation frequencies to identify a magneto-elastic resonant frequency value for said second sensor.
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21. A method of sensing an analyte with a sensor having a chemically responsive material adhered to a base magnetostrictive element, the sensor having a magneto-elastic resonant frequency, comprising the steps of:
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applying a time-varying magnetic field;
measuring a first and second value for magneto-elastic emission intensity of the sensor with a receiver operating at, respectively, a first and second interrogation frequency; and
using a ratio of said first and second values to identify a change in mass, of the sensor due to the chemical responsiveness of said sensor to said analyte. - View Dependent Claims (22, 23, 24, 25, 26)
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27. A method of sensing an analyte with a sensor having a chemically responsive material adhered to a base magnetostrictive element, comprising the steps of:
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applying a time-varying magnetic field;
measuring a plurality of successive values for magneto-elastic emission intensity of the sensor with a receiver operating over a range of successive interrogation frequencies to identify a magneto-elastic resonant frequency value for the sensor;
pre-correlating a series of resonant frequency values taken for the sensor and a corresponding series of mass values for the sensor; and
using said identified magneto-elastic resonant frequency value and said step of pre-correlating to identify a change in mass, of the sensor. - View Dependent Claims (28, 30)
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29. A method of sensing an analyte with a sensor having a chemically responsive material adhered to a base magnetostrictive element comprising the steps of:
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applying a time-varying magnetic field;
applying a DC bias magnetic field;
measuring a plurality of successive values for magneto-elastic emission intensity of the sensor with a receiver operating over a range of successive interrogation frequencies to identify a magneto-elastic resonant frequency value for the sensor;
pre-correlating a series of resonant frequency values taken for the sensor and a corresponding series of material stiffness values for the sensor; and
using said identified magneto-elastic resonant frequency value and said step of pre-correlating to identify a change in material stiffness of the sensor;
wherein said receiver is an electromagnetic pick-up coil and said element is made of an alloy that remains generally unchanged over a preselected range of temperatures.
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Specification