Method and apparatus for characterizing materials by using a mechanical resonator
First Claim
1. A method for measuring a property of a plurality of liquid compositions using a plurality of tuning fork resonators, the method comprising:
- providing an array of sample wells;
placing each of said plurality of liquid compositions in a separate sample well;
placing one of said plurality of tuning fork resonators in a first of said plurality of liquid compositions such that at least a portion of said one of said plurality of tuning fork resonators is surrounded by said first of said plurality of liquid compositions;
placing another of said plurality of tuning fork resonators in a second of said plurality of liquid compositions such that at least a portion of said another of said plurality of tuning fork resonators is surrounded by said second of said plurality of liquid compositions;
applying a variable frequency input signal to a measurement circuit coupled with said one of said plurality of tuning fork resonators to oscillate said one of said plurality of tuning fork resonators;
applying a variable frequency input signal to a measurement circuit coupled with said another of said plurality of tuning fork resonators to oscillate said another of said plurality of tuning fork resonators wherein the measurement circuit coupled to said one of said plurality of tuning fork resonators and the measurement circuit coupled to said another of said plurality of tuning fork resonators may be the same circuit or two separate circuits;
varying a frequency of the variable frequency input signal associated with said one of said plurality of tuning fork resonators over a predetermined frequency range to obtain a frequency-dependent resonator response of said one of said plurality of tuning fork resonators;
varying a frequency of the variable frequency input signal associated with said another of said plurality of tuning fork resonators over a predetermined frequency range to obtain a frequency-dependent resonator response of said another of said plurality of tuning fork resonators; and
analyzing the resonator responses of said one of said plurality of tuning fork resonators and said another of said plurality of tuning fork resonators to measure said property of said first of said plurality of liquid compositions and said second of said plurality of liquid compositions.
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Abstract
A method and apparatus for measuring properties of a liquid composition includes a mechanical resonator, such as a thickness shear mode resonator or a tuning fork resonator, connected to a measurement circuit. The measurement circuit provides a variable frequency input signal to the tuning fork, 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 liquid. The input signal is then sent to the mechanical resonator and swept over a selected frequency range, preferably less than 1 MHz to prevent the liquid being tested from exhibiting gel-like characteristics and causing false readings. The mechanical resonator'"'"'s response over the frequency range depends on various characteristics of the liquid being tested, such as the temperature, viscosity, and other physical properties. Particular mechanical resonators, such as tuning fork resonators, can also be used to measure a liquid composition'"'"'s electrical properties, such as the dielectric constant and conductivity, because the tuning fork'"'"'s structure allows a high degree of electrical coupling between the tuning fork and the surrounding liquid. The mechanical resonator can be covered with a coating to impart additional special detection properties to the resonator, and multiple resonators can be attached together as a single sensor to obtain multiple frequency responses. The invention is particularly suitable for combinatorial chemistry applications, which require rapid analysis of chemical properties for screening.
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Citations
19 Claims
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1. A method for measuring a property of a plurality of liquid compositions using a plurality of tuning fork resonators, the method comprising:
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providing an array of sample wells;
placing each of said plurality of liquid compositions in a separate sample well;
placing one of said plurality of tuning fork resonators in a first of said plurality of liquid compositions such that at least a portion of said one of said plurality of tuning fork resonators is surrounded by said first of said plurality of liquid compositions;
placing another of said plurality of tuning fork resonators in a second of said plurality of liquid compositions such that at least a portion of said another of said plurality of tuning fork resonators is surrounded by said second of said plurality of liquid compositions;
applying a variable frequency input signal to a measurement circuit coupled with said one of said plurality of tuning fork resonators to oscillate said one of said plurality of tuning fork resonators;
applying a variable frequency input signal to a measurement circuit coupled with said another of said plurality of tuning fork resonators to oscillate said another of said plurality of tuning fork resonators wherein the measurement circuit coupled to said one of said plurality of tuning fork resonators and the measurement circuit coupled to said another of said plurality of tuning fork resonators may be the same circuit or two separate circuits;
varying a frequency of the variable frequency input signal associated with said one of said plurality of tuning fork resonators over a predetermined frequency range to obtain a frequency-dependent resonator response of said one of said plurality of tuning fork resonators;
varying a frequency of the variable frequency input signal associated with said another of said plurality of tuning fork resonators over a predetermined frequency range to obtain a frequency-dependent resonator response of said another of said plurality of tuning fork resonators; and
analyzing the resonator responses of said one of said plurality of tuning fork resonators and said another of said plurality of tuning fork resonators to measure said property of said first of said plurality of liquid compositions and said second of said plurality of liquid compositions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus for measuring a property of a plurality of liquid compositions, comprising:
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an array of tuning fork resonators;
an array of sample wells for holding said plurality of liquid compositions;
a measurement circuit coupled with said array of tuning fork resonators, said measurement circuit having a signal generator for generating a variable frequency input signal to cause said array of tuning fork resonators to oscillate; and
a receiver coupled to the measurement circuit to output a frequency response of said array of tuning fork resonators;
wherein said measurement circuit and said receiver are coupled with said array of tuning fork resonators to obtain a frequency response associated with each of said plurality of liquid compositions. - View Dependent Claims (13, 14, 15, 16, 17)
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18. An apparatus for measuring a property of a fluid composition, comprising:
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a plurality of tuning fork resonators, each tuning fork resonator having a different resonator response characteristic;
means for containing the fluid composition;
a measurement circuit coupled with said plurality of tuning fork resonators, said measurement circuit having a signal generator for generating a variable frequency input signal to cause at least one of said plurality of tuning fork resonators to oscillate; and
a receiver coupled to the measurement circuit to output a frequency response of said plurality of tuning fork resonators. - View Dependent Claims (19)
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Specification