Apparatus for measuring a sorbate dispersed in a fluid stream

• US 4,055,072 A
• Filed: 09/19/1975
• Issued: 10/25/1977
• Est. Priority Date: 09/19/1975
• Status: Expired due to Term

• Current Assignee: Fletcher James C Administrator of The National Aeronautics and Space Administration With Respect To An Invention of, Otis L. Updike
• Original Assignee: Fletcher James C Administrator of The National Aeronautics and Space Administration With Respect To An Invention of, Otis L. Updike
• Inventors: Fletcher, James C. Administrator of the National Aeronautics and Space Administration, with respect to an invention of, Updike, Otis L.
• Primary Examiner(s): Myracle, Jerry W.
• Assistant Examiner(s): Kreitman, Stephen A.
• Application Number:
  US05/615,030
• Time in Patent Office: 767 Days
• Field of Search: 73/23, 73/67, 73/67.2, 73/DIG. 2, 357/26.25, 357/232 R, 357/232 E, 357/254 R, 357/254 E, 333/30 R
• US Class Current: 73/24.01
• CPC Class Codes: G01N 2291/012 Phase angle
• CPC Class Codes: G01N 2291/015 Attenuation, scattering
• CPC Class Codes: G01N 2291/0256 Adsorption, desorption, surface mass change, e.g. on biosensors
• CPC Class Codes: G01N 2291/0422 Shear waves, transverse waves, horizontally polarised waves
• CPC Class Codes: G01N 2291/0423 Surface waves, e.g. Rayleigh waves, Love waves
• CPC Class Codes: G01N 2291/0426 Bulk waves, e.g. quartz crystal microbalance, torsional waves
• CPC Class Codes: G01N 29/022 Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices microdevices per se B81B
• CPC Class Codes: G01N 30/00 Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation G01N3/00, G01N5/00, G01N7/00, G01N9/00, G01N11/00, G01N13/00, G01N15/00, G01N17/00, G01N19/00, G01N21/00, G01N22/00, G01N23/00, G01N24/00, G01N25/00, G01N27/00, G01N29/00 take precedence

Abstract

An apparatus for measuring a sorbate dispersed or dissolved in a fluid stream and comprising an oscillator for generating a first alternating-current signal, an acoustic transmission line for disposition in the fluid stream and including an elongated body having a surface capable of sorbing an amount of the sorbate to be measured representative of the concentration thereof in the fluid stream, the body being capable of propagating acoustic energy along its length from one end portion to another end portion, the propagated acoustic energy being damped in amplitude and shifted in phase such that the change in amplitude or phase is proportional to the amount of sorbate sorbed by the surface, a first transducer for converting the alternating current signal to acoustic energy and for applying the acoustic energy to the one end portion, a second transducer for converting the acoustic energy propagated to the other end portion to a corresponding electrical signal, and a comparator for comparing the electrical signal to the alternating-current signal for developing an output signal corresponding to a difference therebetween, the output signal being indicative of the concentration of the sorbate in the fluid stream.

Claims

1. Apparatus for measuring a sorbate dispersed in a fluid stream comprising:

a signal source means for generating an alternating-current signal;

acoustic transmission line means for disposition in the fluid stream and including an elongated body having a surface capable of sorbing an amount of a first sorbate to be measured representative of the concentration thereof in the fluid stream, said body being capable of propagating acoustic energy along its length from one end portion to another end portion, the propagated acoustic energy being damped in amplitude and shifted in phase such that the change in amplitude or phase is proportional to the amount of sorbate sorbed by said surface;

first transducing means for converting said alternating current signal to acoustic energy and for applying said acoustic energy to said one end portion;

second transducing means for converting the acoustic energy propagated to said other end portion to a corresponding first electrical signal; and

comparator means for comparing said first electrical signal to said alternating current signal and for developing an output signal corresponding to a difference therebetween, said output signal being indicative of the concentration of the sorbate in the fluid stream.

2. Apparatus for measuring a sorbate dispersed in a fluid stream as recited in claim 1 wherein said comparator means is a phase comparator.

3. Apparatus for measuring a sorbate dispersed in a fluid stream as recited in claim 1 wherein said comparator means is an amplitude comparator.

4. Apparatus for measuring a sorbate dispersed in a fluid stream as recited in claim 1 and further including means for attenuating said alternating current signal to an amplitude appropriate for comparison with said electrical signal.

5. Apparatus for measuring a sorbate dispersed in a fluid stream as recited in claim 1 and further including means for accumulating the output signal over a period of time and means responsive to the cumulative output signal and operative to provide an indication when said cumulative output signal exceeds a predetermined level.

6. Apparatus for measuring a sorbate dispersed in a fluid stream as recited in claim 1 wherein said surface is formed by an absorbent film disposed in covering relationship over said body, said film serving to absorb said sorbate.

7. Apparatus for measuring a sorbate dispersed in a fluid stream as recited in claim 1 wherein said body is formed from a material having a low temperature coefficient of propagation velocity and said first and second transducing means are interdigital transducer arrays formed on said surface.

8. Apparatus for measuring a sorbate dispersed in a fluid stream as recited in claim 1 wherein said elongated body is a block of material having a low temperature coefficient of propagation velocity, and wherein said first and second transducing means are crystals, when energized by said alternating current signal, said first crystal serves to periodically move and induce shear wave motion in said body, said second crystal being operative to respond to the wave motion propagated through said body and to produce said electrical signal.

9. Apparatus for measuring a sorbate dispersed in a fluid stream as recited in claim 8 wherein said body and said first and second transducing means are formed from a unitary block of piezoelectric material.

10. Apparatus for measuring a sorbate dispersed in a fluid stream as recited in claim 1 and further comprising:

second acoustic transmission line means for disposition in the fluid stream and including a second elongated body having a second surface capable of sorbing an amount of a second sorbate to be measured representative of the concentration thereof in the fluid stream, said second body being capable of propagating acoustic energy along its length from one end portion to another end portion, the propagated acoustic energy being damped in amplitude and shifted in phase such that the change in amplitude or phase is proportional to the amount of the second sorbate sorbed by said second surface;

third transducing means for converting said alternating-current signal to acoustic energy and for applying the acoustic energy to said one end portion of said second body; and

fourth transducing means for converting the acoustic energy propagated to said other end portion of said second body to a corresponding second electrical signal for input to said comparator means, said comparator means serving to compare said first electrical signal and said second electrical signal and to develop an output signal corresponding to the difference in concentrations of the first and second sorbates in the fluid stream.

11. Apparatus for measuring a sorbate dispersed in a fluid stream as recited in claim 1 and further comprising:

second acoustic transmission line means for disposition in a second fluid stream and including a second elongated body having a second surface capable to sorbing an amount of said sorbate to be measured representative of the concentration thereof in said second fluid stream, said second body being capable of propagating acoustic energy along its length from one end portion to another end portion, the propagated acoustic energy being damped in amplitude and shifted in phase such that the change in amplitude or phase is proportional to the amount of said sorbate sorbed by said second surface;

third transducing means for converting said alternating-current signal to acoustic energy and for applying the acoustic energy to said one end portion of said second body; and

fourth transducing means for converting the acoustic energy propagated to said other end portion of said second body to a corresponding second electrical signal for input to said comparator means, said comparator means serving to compare said first electrical signal and said second electrical signal and to develop an output signal corresponding to the difference in concentrations of said sorbate in said first and second fluid streams.

12. Apparatus for measuring first and second sorbates dispersed in a fluid stream comprising:

signal source means for generating an alternating-current signal;

acoustic transmission line means for disposition in the fluid stream and including an elongated body having a first surface capable of sorbing an amount of a first sorbate to be measured representative of the concentration thereof in the fluid stream, said body being capable of propagating acoustic energy along its length from a central portion to a first end portion, the propagated acoustic energy being damped in amplitude and shifted in phase such that the change in amplitude or phase is proportional to the amount of said first sorbate sorbed by said first surface, and having a second surface capable of sorbing an amount of a second sorbate to be measured representative of the concentration thereof in the fluid stream, said body being capable of propagating acoustic energy along its length from said central portion to a second end portion, such propagated energy being damped in amplitude and shifted in phase such that the change in amplitude or phase is proportional to the amount of said second sorbate sorbed by said second surface;

first transducing means for converting said alternating-current signal to acoustic energy and for applying said acoustic energy to said central portion;

second transducing means for converting the acoustic energy propagated to said first end portion to a corresponding first electrical signal;

third transducing means for converting the acoustic energy propagated to said second end portion to a corresponding second electrical signal;

first comparator means for comparing said first electrical signal to said alternating-current signal and for developing a first output signal corresponding to a difference therebetween, said first output signal being indicative of the concentration of said first sorbate in the fluid stream; and

second comparator means for comparing said second electrical signal to said alternating-current signal and for developing a second output signal corresponding to a difference therebetween, said second output signal being indicative of the concentration of said second sorbate in the fluid stream.

13. Apparatus for measuring a sorbate dispersed in a fluid stream comprising:

signal source means for generating an alternating-current signal;

acoustic transmission line means for disposition in the fluid stream and including an elongated body having a surface capable of sorbing an amount of a first sorbate to be measured representative of the concentration thereof in the fluid stream, said body being capable of propagating acoustic energy along its length from one end portion to another end portion, the propagated acoustic energy being damped in amplitude and shifted in phase such that the change in amplitude or phase is proportional to the amount of sorbate sorbed by said surface;

first transducing means for converting said alternating current signal to acoustic energy and for applying said acoustic energy to said one end portion;

second transducing means for converting the acoustic energy propagated to said other end portion to a corresponding first electrical signal;

comparator means for comparing said first electrical signal to said alternating current signal and for developing an output signal corresponding to a difference therebetween, said output signal being indicative of the concentration of the sorbate in the fluid stream;

said body including a length of wire; and

said first and second transducing means being magnetostrictive devices disposed around said wire at respective end portions thereof, said first magnetostrictive device serving to torsionally vibrate said wire and said second magnetostrictive device serving to convert the torsional vibrations propagated through said wire to said other end portion to a corresponding electrical signal.