Electrolysis: processes – compositions used therein – and methods – Electrolytic analysis or testing
Reexamination Certificate
1999-11-22
2001-09-18
Tung, T. (Department: 1743)
Electrolysis: processes, compositions used therein, and methods
Electrolytic analysis or testing
C205S777500, C205S789000, C205S793500, C204S400000, C204S403060, C204S412000, C204S416000, C204S418000, C422S067000, C422S068100
Reexamination Certificate
active
06290838
ABSTRACT:
The present invention relates to methods and to apparatuses which are intended for characterising liquids, i.e. methods and apparatuses which are capable of generating data which characterise a sample of liquid which is provided to them. The invention especially relates to methods and to apparatuses which aim to distinguish liquid products from one another and/or to identify liquids. The invention enables, inter alia, an ultra-rapid quality control of liquid matrices.
It is often necessary to characterise samples of liquid, for example for the quality control of liquid matrices such as water, milk, wine, etc., and in fields as varied as agri-foodstuffs, cosmetics, the environment and the medical field. The classical techniques used to this end are liquid chromatography, GC/MS (gas chromatography+mass spectrometry) or capillary electrophoresis or analysis carried out which uses ion-selective electrodes. Such methods characterise the samples whilst at the same time determine the chemical composition of these or, at least, the content, in the sample, of a particular compound.
Such methods are long and costly to implement. The average analysis time in liquid chromatography, for example, is situated between 10 and 20 minutes. Furthermore, most of the time, a preparation of the sample is necessary.
In the aim of reducing the time necessary for characterising liquids, certain researchers have proposed adopting an approach based not upon the identification of the components making a part of the liquid, but upon an overall characterisation of the liquid. This approach consists of using sensors which are sensitive to multiple components at the same time, which generate representative signals from the liquid, and in the use of techniques of recognition of units in order to create, from these signals, <<an impression>> of the liquid (i.e. data characterising the liquid). For example, in the article: <<Tasting of beverages using an electronic tongue based on potentiometric sensor array>> by Legin et al (Eurosensors X, Leuven, Belgium, 8
th
-11
th
September 1996), an apparatus is described which is intended for a use in the quality control of drinks, this apparatus comprising a group of chemical sensors in the solid state. The characterisation of foods is treated in the book <<Characterisation of Food: emerging methods>> (ed. A. G. Gaonkar, Elsevier Science, 1995), in the sixteenth chapter of which liquid sensors are proposed the voltage change of which varies in the presence of liquids having different gustative characteristics.
However, up to the present day, no apparatus of detection by impression in liquid matrices has resulted from the various theoretical propositions. One of the reasons which would explain this lack consists in this fact that in practice, any apparatus for characterising liquids must have a high discrimination capacity from which a high enough capacity to differentiate various liquids. It has been discovered that the sensors must be non-specific or not very specific, the detection of a given compound originates therefore from crossed factors of sensors. In the devices which have been proposed up to now, the sensors are too selective and specific to enable the rapid detection of a given compound.
The aim of the present invention is a method and an apparatus for characterising liquids having a high resolution and which are capable of arriving rapidly at a reliable characterisation of a sample of liquid, and this by the development of non-selective sensors, of large specificity, and the crossing of sensors of different types of technologies. In the case in which from the group of sensors employed there exists a plurality of sensors of a same type of technology, it can prove to be advantageous to manufacture the latter in using various depositing means so as to obtain various thicknesses of coating or of sensitive element and, therefore, sensors the specificity of which varies.
More particularly, the present invention provides a method and an apparatus according to which at least one measuring electrode intended to be soaked in a sample of liquid to be characterised is (are) equipped with sensors of at least two different types of technology, i.e., sensors which have respective physical or chemical reactions of different nature during the immersion of the sensor concerned in a liquid. The output signals from these sensors used in the apparatus according to the invention are captured and processed in order to determine an impression for the liquid concerned.
One of the main advantages of the present invention consists of its high capacities of resolution and of discrimination obtained by virtue of the use of signals originating from liquid sensors of several types of technology.
Preferably, the sensors of different types of technology are selected from the group consisting of lipid sensors, quartz microbalances, surface acoustic wave device sensors, also known under the name of SAW devices, ion-selective sensors, biosensors, and chemical microsensors. The sensors of the technologies of this group are non-selective or not very selective, i.e. that instead of reacting with one sole component of the sample or with one sole main gustative principle (sweet, salty, etc.), they react in an overall manner with the <<taste>> of the liquid. In other terms, each sensor reacts with several of the main gustative qualities. (This group could be enlarged in case of development of sensors according to a new type of technology). When these sensors are soaked in a liquid, their electrical or piezoelectrical properties change, for example, the voltage, the electrical resistance, the frequency of oscillation, etc.
The samples of liquids interact with the sensors of different types of technology according to the chemical or physical processes of different nature. The output signals from the respective sensors of different technologies therefore reflect the different properties of the samples of liquids and/or of the components of these. The use of several technologies leads, during the analysis of various liquids, to an increase in the variability of the signals and therefore increases the capacity of discrimination of the apparatus.
In certain applications, it could prove to be useful to associate sensors of different types of technology with sensors of one sole type of technology comprising layers deposited according to different procedures. Preferably, in these sensors of the same type of technology, the thickness or the composition of at least one respective sensitive layer of these sensors varies. This enables increasing the capacity of discrimination of the system even further.
It can also prove to be interesting to associate, with the signals originating from the main sensors, additional data of classical chemical analysis such as the pH, the oxygen content, the CO
2
content, the chlorine content, the measurement of a specific compound or finally the colour.
The method and the apparatus according to the present invention give, in a few seconds, a result which is equivalent to that given after 10 to 20 minutes by a chromatography system. Further, according to the present invention, no preparation of the sample is necessary.
The instruments according to the preferred embodiments of the invention enable having an impression which characterises a sample of liquid and enable comparing it to a learning base or database so as to detect or to identify the liquid concerned. This learning base or database is established during a learning phase of the system. Once the learning phase of the system is accomplished, the system can be used by a person who has no training in the field of analysis.
The instruments according to the preferred embodiments of the invention enable an ultra-rapid characterisation of liquids. They offer a very wide variety of applications in fields such as the quality control of liquid matrices, as well as in many other fields a few examples of which are set forth at the end of the description. These instruments enable qu
Lucas Quitterie
Mifsud Jean-Christophe
Alpha M.O.S.
Noguerola Alex
Tung T.
Weingarten, Schurgin Gagnebin & Hayes LLP
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