Method and apparatus for characterizing materials by using a mechanical resonator

• US 6,336,353 B2
• Filed: 03/07/2001
• Issued: 01/08/2002
• Est. Priority Date: 10/08/1997
• Status: Expired due to Term

• Current Assignee: Meas France
• Original Assignee: Symyx Technologies Incorporated (Dassault Systemes SA)
• Inventors: Bennett, James, Matsiev, Leonid, McFarland, Eric
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): MILLER, ROSE MARY
• Application Number:
  US09/801,165
• Publication Number:
  US 20010010174A1
• Time in Patent Office: 307 Days
• Field of Search: 73/240.1, 73/240.3, 73/240.4, 73/240.5, 73/240.6, 73/300.1, 73/300.4, 73/310.1, 73/310.2, 73/310.3, 73/310.5, 73/310.6, 73/32.A, 73/32.R, 73/530.1, 73/540.1, 73/540.2, 73/542.3, 73/544.1, 73/614.5, 73/617.5, 73/617.9, 735/79, 310/360, 310/316, 310/320, 422/68.1, 422/75, 422/98
• US Class Current: 73/24.06
• CPC Class Codes: B01J 2219/00704 integrated with the reactor apparatus
• CPC Class Codes: G01H 13/00 Measuring resonant frequency
• CPC Class Codes: G01N 11/16 by measuring damping effect upon oscillatory body
• CPC Class Codes: G01N 2009/006 vibrating tube, tuning fork
• CPC Class Codes: G01N 2291/014 Resonance or resonant frequency
• CPC Class Codes: G01N 2291/0224 Mixtures of three or more liquids
• CPC Class Codes: G01N 2291/0255 (Bio)chemical reactions, e.g. on biosensors
• CPC Class Codes: G01N 2291/02818 Density, viscosity
• CPC Class Codes: G01N 2291/02863 Electric or magnetic parameters
• 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 2291/0427 Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
• 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 29/036 by measuring frequency or resonance of acoustic waves
• CPC Class Codes: G01N 29/348 with frequency characteristics, e.g. single frequency signals, chirp signals measuring frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04; measuring frequency or analysing frequency spectra G01R23/00
• CPC Class Codes: G01N 29/42 by frequency filtering or by tuning to resonant frequency
• CPC Class Codes: G01N 29/4418 with a model, e.g. best-fit, regression analysis
• CPC Class Codes: G01N 5/04 by removing a component, e.g. by evaporation, and weighing the remainder
• CPC Class Codes: G01N 9/002 using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis G01N9/34 takes precedence

Abstract

A method and apparatus for measuring properties of a fluid composition includes a mechanical resonator connected to a measurement circuit. The measurement circuit provides a variable frequency input signal to the mechanical resonator, causing the mechanical resonator to oscillate. To test the properties of a liquid composition, the mechanical resonator is placed inside a sample well containing a small amount of the fluid. The input signal is then sent to the mechanical resonator and swept over a selected frequency range. The mechanical resonator'"'"'s response over the frequency range depends on various characteristics of the fluid being tested, such as the temperature, viscosity, and other physical properties. The invention is particularly suitable for combinatorial chemistry applications, which require rapid analysis of chemical properties for screening.

Claims

1. A method for monitoring a change in a property of a fluid composition, the method comprising:

placing the mechanical resonator in the fluid composition such that at least a portion of the mechanical resonator is submerged in the fluid composition;

applying a variable frequency input signal to a measurement circuit coupled with the mechanical resonator to oscillate the mechanical resonator;

varying the frequency of the variable frequency input signal over a predetermined frequency range to obtain a frequency-dependent resonator response of the mechanical resonator;

determining the property of the fluid composition based on the mechanical resonator response;

repeating the applying, varying, and determining steps over time; and

monitoring over time a change in the mechanical resonator response reflecting the change in property of the fluid composition.

2. The method of claim 1, the change monitored in the monitoring step is a physical change in the fluid composition.

3. The method of claim 2, wherein the physical change in the fluid composition is a liquid-to-solid, liquid to liquid, liquid to vapor, or vapor to liquid state transformation of the fluid composition.

4. The method of claim 1, wherein the change monitored in the monitoring step is a chemical transformation of the fluid composition.

5. The method of claim 4, wherein the chemical transformation monitored in the monitoring step is a polymerization reaction.

6. The method of claim 1, wherein said method measures a property selected from the group consisting of specific weight, viscosity, temperature, dielectric constant and conductivity of the fluid composition.

7. The method of claim 6, wherein the method measures the property over time.

8. The method of claim 6, wherein said method simultaneously measures at least two properties selected from the group consisting of specific weight, viscosity, temperature, dielectric constant and conductivity of the fluid composition.

9. The method of claim 8, wherein the method measures said at least two properties over time.

10. The method of claim 1, further comprising the step of coating the mechanical resonator with a coating material.

11. The method of claim 10, wherein the material used in said coating step is a functionality designed to change the resonator response of the mechanical resonator if a selected substance is present in the fluid composition.

12. The method of claim 11, wherein said functionality used in the coating step contains receptor molecules for attracting molecules of the selected substance in the fluid composition to change the resonator response.

13. The method of claim 1, wherein the placing step includes placing a plurality of mechanical resonators in the fluid composition.

14. The method of claim 13, wherein each of said plurality of mechanical resonators has a different resonator response characteristic, and wherein the varying step varies the frequency of the variable input signal over a plurality of frequency dependent resonator responses from the plurality of mechanical resonators.

15. The method of claim 1, wherein the mechanical resonator placed in the placing step is a multiple-mode resonator that can be operated in more than one mechanical mode, and wherein the varying step comprises varying the frequency of the variable frequency input signal to obtain a plurality of frequency-dependent resonator responses corresponding to said more than one mechanical mode.

16. The method of claim 1, wherein the mechanical resonator is a unimorph/bimorph resonator.