Remote magneto-elastic analyte, viscosity and temperature sensing apparatus and associated methods of sensing

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 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.

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;
• 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.

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:

• 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.

A method of sensing an analyte with a sensor having a chemically responsive material adhered to a base magnetostrictive element, comprising the steps of:

• 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.

A method of sensing an analyte with a sensor having a chemically responsive material adhered to a base magnetostrictive element comprising the steps of:

• 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.