Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Electrical signal parameter measurement system
Reexamination Certificate
2001-07-03
2003-11-04
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Electrical signal parameter measurement system
C435S006120, C435S007210, C702S127000
Reexamination Certificate
active
06643593
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for determining at least one property of a test substance, a device for determining at least one property of a test substance, the use of this device and a computer-readable memory containing a computer program for determining at least one property of a test substance.
2. Description of the Related Art
Emulsions are disperse systems of two liquids, or phases, that are immiscible or only partially miscible with one another, one of which is finely divided in the other. Accordingly, they comprise an inner, or disperse, phase and an outer, or continuous, phase, with the inner phase being the fraction of the system that is typically present in small droplets. The term suspensions is used to mean disperse systems in which a solid substance is finely divided in a liquid substance. The term foam is used to mean a disperse distribution of gas-filled bubbles in a liquid and/or solid medium, which is created e.g. by vigorous impact, shaking, spraying, stirring and/or chemical reactions. Emulsions and suspensions, as well as foams, are very important in many fields of industrial, health and household technology, for example for food, cosmetics, pharmaceuticals and dyes. Owing to this, there is significant interest in methods and devices for the quality control and characterization of emulsions and suspensions. Particularly important properties of emulsions, which are directly related to their quality, are the volume ratio of the two phases as well as the drop size, or the drop size distribution, of the drops in the disperse phase of the emulsion.
To determine the volume ratios of the disperse and continuous phases of emulsions, it is customary to use the density of the emulsion. Furthermore, the volume ratio can also be obtained from final drying of the emulsion. However, such determination of the volume ratio by measuring the density of the components that are used is successful only if two pure components are present, or if the precise composition of the respective components is known at any time. The same limitations with respect to the possible compositions of the emulsions also exist for said method involving final drying and weighing of the emulsions. Drying analysis is also time-consuming, and cannot therefore be used as an in-situ, or in-line, method during the emulsification process. In order to determine the drop size, or the drop size distribution, of the disperse phase, it is customary to use laser diffraction spectrometry or ultrasound extinction experiments. For in-line monitoring, fiber optic sensors are used. In this case, however, the drop size determination is restricted to low-concentration emulsions. Furthermore, said fiber optic sensors can only be used to determine the specific surface area of the disperse phase, and therefore merely an average drop size—but not the drop size distribution.
It is an object of the invention to provide a simple, cost-effective and fast method for determining properties of emulsions and/or suspensions and/or foams, which can preferably also be used as an in-line method during the production of the emulsion and/or suspension or immediately following its production. It is also an object of the invention to provide a corresponding device and a corresponding computer-readable storage medium having a computer program stored thereon for determining properties of emulsions and/or suspensions and/or foams.
SUMMARY OF THE INVENTION
According to the method according to the invention, properties of test substances, which comprise test emulsions and/or test suspensions and/or test foams, are determined insofar as these properties have an influence on the dielectric properties of the test substance. In this case, the term emulsions is used to mean disperse systems of two liquids, or phases, that are immiscible or only partially miscible with one another, one of which is finely divided in the other. An emulsion therefore comprises an inner, or disperse, phase and an outer, or continuous, phase, with the inner phase being the fraction of the system that is typically present in small droplets. Conversely, the term suspensions is used to mean disperse systems in which a solid substance is finely divided in a liquid substance. The term foam, or spumoid, is used to mean a disperse distribution of gas-filled bubbles or pores or cells in a liquid and/or solid medium, which is created e.g. by vigorous impact, shaking, spraying, stirring and/or chemical reactions. Furthermore, the property in question should not be the same as the dielectric properties of the test substance, but should merely represent a property that influences the dielectric properties, i.e. is not independent of them. Surprisingly, such properties of a test substance can be determined from its dielectric properties. In this case, the real or imaginary part of the complex dielectric constant of the test substance is sufficient, said part being established at one frequency, typically by a measurement. An advantageous, in particular redundant, determination is possible if both the real part and the imaginary part of the dielectric constant are established. It is also conceivable to establish the dielectric constant of the test substance by means of an impedance measurement.
According to the invention, the real and/or imaginary part(s) of the dielectric constant of the test substance is established at a plurality of frequencies, i.e. at two or more. Accordingly, an (optionally complex) dielectric spectrum of the test substance is used, although just the real or the imaginary part of the dielectric constant is typically sufficient for determining the test substance property in question. An advantageous, in particular redundant, determination is possible if both the real part and the imaginary part of the dielectric constant is spectroscopically recorded.
According to a preferred embodiment of the invention, the test substance properties to be determined are determined with the assistance of at least one real and/or imaginary part of the dielectric constant of at least one reference emulsion and/or of at least one reference suspension and/or of at least one reference foam as at least one reference substance, in which the at least one property to be determined is known. The reference suspension, which may be a reference emulsion and/or a reference suspension, is typically a substance that is very similar to or corresponds to the test substance, but in which the property in question, i.e. the material parameter in question, is known. From the real and/or imaginary part(s) of the dielectric constant of such a reference substance, in conjunction with the aforementioned method, it is possible to determine the test substance property in question. Typically, the real and/or imaginary part(s) of the dielectric constant of the reference substance at that frequency or those frequencies at which the real and/or imaginary part(s) of the dielectric constant of the test substance has been established, is used for the determination.
According to another embodiment, the method according to the invention comprises the further steps of preparing the at least one reference substance; and establishing the real and/or imaginary part(s) of the dielectric constant of the reference substance at at least one or a plurality of frequencies.
This makes it possible, even without the assistance of, for example, collections of material properties or data sheets, to use reference substances whose property in question—but not its dielectric constant—is known. The steps of establishing the real and/or imaginary part(s) of the dielectric constant of the reference substance are therefore used to compile reference data that are preferably used to calibrate the actual method of determining the property of the test substance.
Preferably, the real and/or imaginary part(s) of the dielectric constants of the at least one reference substance is established at a plurality of frequencies (two or more), i.e. a spectrum of the (complex) dielectric constan
Danner Thomas
Regier Marc
Schubert Helmar
Barlow John
Casella Anthony J.
Hespos Gerald E.
Le John
Universitat Karlsruhe
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