GB2248301A - Apparatus and method for the detection of changes in the composition of a material - Google Patents
Apparatus and method for the detection of changes in the composition of a material Download PDFInfo
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- GB2248301A GB2248301A GB9019980A GB9019980A GB2248301A GB 2248301 A GB2248301 A GB 2248301A GB 9019980 A GB9019980 A GB 9019980A GB 9019980 A GB9019980 A GB 9019980A GB 2248301 A GB2248301 A GB 2248301A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/028—Circuits therefor
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- General Health & Medical Sciences (AREA)
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- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
Changes in the composition of a material are detected by placing it between electrical terminals and applying a potential difference across the terminals. A resulting signal, which depends on the impedence properties of the material, gives an indication of composition. <IMAGE>
Description
Method of Detection of ChanRes of COmPOSitiOn of Materials and Apparatus therefor
This invention relates to a method of detection Of changes of composition of materials and apparatus therefor.
In detecting substances and especially in monitoring the composition of materials with reference to the quantity of a substance in it, it is known to take samples for analysis. If such materials are enclosed in a vessel, for example a conduit or tank in a chemical plant or an analytical instrument the construction of the vessel may be complicated by a need to remove samples, material is lost and delay in securing results may be encountered. It has been proposed to use probes, for example electrodes located in such vessels to give instantaneous results but this also complicates construction of the vessel and may require regular replacement of the probes and cause changes in the materials to be tested for example due to electrolysis.
This invention provides a method of detection of changes in composition of materials which does not require the taking of samples and in which the sample may be detected from outside the wall of any such vessel, thus avoiding complications in construction.
The invention comprises apparatus for the detection of changes in the composition of a material which comprises a first electrical terminal which, in use, is inductively coupled to a second electrical terminal through a zone to which a material to be tested can be introduced, means substantially to prevent inductive coupling of the terminals other than through the said zone, means to apply a potential to the first terminal, means to vary the said potential and means to detect, directly or indirectly, an electrical signal of the second terminal related to the composition of a material in the said zone.
The invention also comprises a method of detection of changes in the composition of a material which comprises introducing the material to a zone between a first and second electrical terminal, applying a potential to the first terminal thereby inducing an electrical signal at the second terminal related to the composition of the material in the said zone and detecting, directly or indirectly, the electrical signal induced at the second terminal.
The potential may be applied to the first terminal before, during or after the material is introduced to the zone.
The two terminals, means for holding the material in the said zone and the means to substantially prevent coupling other than via the zone are hereinafter referred to as 'the cell'. When in use, the elements which constitute the cell are preferably located in a fixed relationship to each other by any suitable means for example the cell may be set in a block of insulating material for example epoxy resin, thereby to substantially prevent movement of the elements relative to each other.
The material to be tested may comprise a plurality of components which may be ionic, polar or non-polar, solid, liquid or gas. Suitably the material to be tested comprises a two component composition in which the components form a single phase material for example a solution.
Other materials which may be detected are those in which the components form multi-phase mixtures, for example slurries, suspensions and immiscible layers.
The zone may be bounded by a vessel for example a pipe or a tank, which is made of a substance which provides minimal coupling between the terminals, for example a plastics material or inorganic material for example glass, PTFE or fused silica.
It is preferred that the zone between the terminals be substantially completely filled with the material to be tested.
The terminals, inter alia, determine the level of sensitivity and resolution of the apparatus. The surface area of the part of the terminals which, in use, faces the zone determines the sensitivity and resolution of the apparatus. There is no theoretical limitation to the arrangement, relative orientation or size of the terminals so long as, in use, the terminals are located at a position sufficiently close to the zone to provide a detectable induced potential at the second terminal.
The terminals comprise an electrically conducting material and each independently of the other, may be made of, or coated with said material which may be for example, carbon or a metallic material, preferably copper or aluminium. In use, the first terminal is suitably coupled to the means to apply and the means to vary the potential applied to tne first terminal and the second terminal is suitably coupled to the detection means by any conventional means, for example, a wire.
When the zone is bounded by a vessel, the terminals suitably comprise elements having faces which, in use, face the vessel and which preferably have a similar contour to that part of the vessel adjacent to the respective terminal. It is preferred that each of the terminals extends around a different substantial part of the vessel and more preferably each extends completely around a different part of the vessel.
For example, if the vessel is cylindrical, the face of the terminal is preferably profiled similarly to at least part of the vessel but is of somewhat increased radius. Preferably the face of the terminal subtends an angle of 45 to 3600, more preferably 90 to 3600 and especially 3600. If the face of the terminal subtends an angle of 3600, the terminal is suitably cylindrical.
It is preferred that the terminals are arranged as close as possible to the vessel and more preferably are in physical contact with the vessel. It is especially preferred that the terminals have a face which is shaped to conform to the contours of the vessel.
The terminals suitably have a face having length and width of from 0.1 to 25, preferably 0.1 to 10 and more preferably 0.5 to 10 times the width of the vessel nearest to the respective terminal. It is preferred that the length of the terminals is from 0.05 to 20, preferably from 0.1 to 10 and more preferably 0.2 to 5 times the width of the terminals.
References to the length or width of the face of a terminal refer to the dimensions of the terminal face when arranged for use, the length being the dimension which is parallel to the longitudinal axis of the vessel and the width being the dimension perpendicular to the length.
Thus, where a terminal comprises a hollow cylinder, the length of the face is equivalent to the height of the cylinder and the width is equivalent to the internal circumference of the cylinder.
The separation between the terminals in use is not critical and will depend on the particular application but it is suitably from 0.01 to 50, preferably from 0.01 to 10 and more preferably from 0.1 to 10 times the width of the vessel.
For example when using the apparatus as a high pressure liquid chromatography detector the separation between the first and second terminal is typically about 100 microns to 10 centimetres. For larger scale applications the separation of the terminals may be appropriately increased and practical factors such as the amount of power required to provide sufficient sensitivity may provide limitations as regards the maximum separation of the terminals.
Where a solid material is to be tested, and the zone is not bounded by a vessel, the shape of the terminals conform to the shape of the solid similarly as they conform to the shape of the vessel in cases where a vessel is used.
The means to prevent coupling of the terminals other than through the zone suitably comprise an electrically earthed barrier made of an electrically conducting material for example carbon or a metallic material, preferably copper or aluminium.
A preferred embodiment of the cell comprises a vessel of circular cross-section which passes through an aperture in a barrier which comprises a sheet, the aperture being preferably of diameter substantially equal to the outside diameter of the vessel. The terminals preferably comprise, for each terminal, a tubular element with an internal diameter substantially equal to the outer diameter of the vessel and length of from 1 to 10 times the outer diameter of the vessel, the terminals being separated by the barrier which is suitably made of copper.
The means to apply and the means to vary a potential applied to the first terminal (the first potential) suitably comprise an alternating potential source or a feed-back circuit. It is preferred that the alternating potential source has a frequency of 10Hz to 1000MHz, preferably 100Hz to 100MHz and more preferably lkHz to 10MHz.
A suitable feed-back circuit may comprise means to feed an electrical signal induced at the second terminal (the second potential) to an amplifier supplying the said first potential whereby the first potential is varied in response to the said second potential. In such an arrangement, a resonant system is established in which the resonant frequency is determined by the composition of the material in the zone and the amplitude of the resonant frequency is a function of the energy transfer characteristics of the material in the zone. This mode of operation is known as 'free running' and the resonant frequency of the circuit and/or amplitude of the induced electrical signal compared with that applied to the first terminal, varies with any changes in the composition of the material in the zone.
In order to provide for greater sensitivity of detection a conventional "Impedance Bridge" comprising two parallel impedance branches, each branch comprising two impedances in series may be used in an arrangement where an alternating potential source is used. One impedance comprises the cell and another comprises a variable impedance.
In use, the bridge is balanced using the variable impedance thereby providing a zero output to the detection means. A change in composition of the material in the cell will change the impedance thereof, unbalancing the bridge and thereby providing an electrical signal at the detection means related to the change in composition of the material in the cell.
The means to detect an electrical signal induced at the second terminal (detection means) are suitably capable of measuring any one or more of the characteristics of the induced electrical signal for example the amplitude or phase of the second potential in comparison with that of the first potential, the absolute amplitude thereof or the resonant frequency of the circuit.
To measure the amplitude of the second potential in an arrangement where an alternating potential source is used, the detection means is coupled to the second terminal by conventional means and suitably detects directly an electrical signal induced at the second terminal.
The detection means suitably comprises a stable wide band amplifier which is coupled to a rectifier circuit and a direct current (d.c.) amplifier.
In order to measure phase changes, the detection means suitably comprises a phase sensitive amplifier having both an input from the second terminal and a reference input of the first potential which amplifier is coupled to a rectifier circuit and a d.c. amplifier. For arrangements which have an "Impedance Bridge", the detection means suitably comprises a rectifier circuit which is coupled to a direct current (d.c.) amplifier. The output of the d.c. amplifier provides a measure of the amplitude of the second potential.
A cathode ray oscilloscope may be used to give direct measurement of the induced potential andlor the applied potential.
In a 'free running' arrangement the resonant frequency of the circuit is suitably measured by coupling the detection means to the circuit at any point. This is an example of indirect detection of an electrical signal at the second terminal since the frequency of the electrical signal at the second terminal will be the same as that at any other point in the resonant circuit. In this case the detection means suitably comprises a stable wide band amplifier coupled to a frequency to voltage converter which is coupled to a d.c amplifier. The output of the d.c. amplifier provides a measure of the resonant frequency of the circuit.
In order to increase the sensitivity of the apparatus, the cell may be located in an electrically earthed housing which suitably comprises an electrically conducting material, for example a metal, preferably a die-cast metal and which optionally comprises an inlet port and an outlet port through which a vessel may pass thereby providing for the material to be tested to pass through and be analysed in the housing.
Conveniently, the housing also comprises electrical connectors insulated from the housing to allow the terminals located therein to be connected to the rest of the electrical circuit apparatus which may be located outside the housing.
The apparatus and method of the invention may be used either quantitatively, with suitable calibration, or qualitatively for the determination of changes in the composition of the material, such as variations in concentration andlor type of material present in the said zone.
To measure amplitude changes due to changes in the composition of a material in arrangements where an alternating potential source is used, the alternating potential source is held at a particular frequency thereby applying a potential to the first terminal and inducing a potential at the second terminal which is related to the composition of the material in the zone between the terminals. The potential induced at the second terminal provides a signal which is converted to a d c.
output which may vary as the composition of the material changes. This gives an indication of the energy transfer characteristics of the composition of the material in the zone.
An alternative arrangement whereby a reference signal from an alternating potential source is inputted to the detection means for comparison with the second potential, (the second potential being induced by the first potential which is provided by the alternating potential source), may give a direct indication of the magnitude of a change in amplitude due to the material in the zone.
For quantitative measurements of any changes in the composition of a material, calibration of the apparatus with a material of known composition (and all other factors which may affect the induced potential are unchanged) is required prior to use with the unknown material.
Qualitative measurements do not require prior calibration of the apparatus. Suitably, for such measurements, the frequency of the alternating potential source is varied until the d.c. output signal is maximised, the alternating potential source is then held at that particular frequency for the duration of the analysis (unless a 'free running' arrangement is used in which case the system establishes its own resonant frequency according to the composition of the material in the zone) and any significant changes in composition of the material present in the system are detected as a change in the d.c. output signal.
This type of analysis is useful in applications where it is required that the composition of the material be monitored for any qualitative change for example in water supply pipelines where the apparatus may be set up to provide a particular value output signal for water having an acceptable level of purity and deviation from that particular composition will be immediately detectable as a variation in the output signal thereby alerting to the possibility of contamination of the water supply.
Specific embodiments of the invention will now be described with reference to the accompanying drawings in which;
FIGURE 1 shows a schematic representation of a detection apparatus for 'free running' operation.
FIGURE 2 shows a schematic representation of a detection apparatus having an "Impedance Bridge" arrangement.
FIGURE 3 shows a schematic representation of detection apparatus having an alternating potential source.
FIGURE 4 shows a schematic representation of the detection apparatus of FIGURE 3 with a reference input to the radio frequency amplifier.
FIGURE 5 shows a section view of a cell.
FIGURE 6 shows a section view of a cell in a housing, the cell being set in an insulating block.
The apparatus of FIGURE 1 comprises, a cell (1), a vessel (11) which passes through the cell (1) and contains the material to be tested, means (2a) (broad range amplifier) to apply a potential to a first terminal located in the cell (1) via coupling means (7), coupling means (8) by which the potential induced in the second terminal located in cell (1) is fed back to the broad range amplifier (2a) thereby forming a complete feed-back circuit and detection means coupled to the circuit (and hence indirectly to the second terminal located in the cell (1)), which comprises a stable wide band amplifier (3) a frequency to voltage converter (4) to provide an electrical signal dependent on the frequency of the circuit and a d.c. amplifier (6).
The feed-back circuit constitutes the means of varying the potential applied to the first terminal since it varies the frequency of the circuit until the resonant frequency thereof is reached.
In use, the amplification factor on the broad range amplifier (2a) is set st a value which provides an electrical signal at the second terminal in the cell (1) and thus also in the coupling means (8) thereby providing a feed-back input to the broad range amplifier (2a) in response to the second potential, thereby establishing a resonant system. The electrical signal at the second terminal provides a signal in the detection means thereby providing a signal at the d.c. amplifier (6) which is related to the composition of the material in the vessel (11).
The apparatus of FIGURE 2 comprises, a cell (1), a vessel (11) which passes through the cell (1) and contains the material to be analysed means (2) (alternating potential source) to apply and to vary A potential supplied to a first terminal located in the cell (1) via coupling means (7) and (10), means (8) to couple the second terminal in the cell (1) to the detection means which comprises a rectifier (5) and a d.c. amplifier (6).
In use, the alternating potential source (2) is held at a particular frequency for the duration of the analysis and the bImpedance Bridge" is balanced using the variable impedance (18) to give a zero output signal at the d.c. amplifier (6). A change in the composition of the material in the vessel (11) will alter the impedance of the cell (1) and hence the balance point of the bridge and provide an output signal thus indicating a change in the composition of the material.
The apparatus shown in FIGURE 3 comprises a cell (1), a vessel (11) which passes through the cell (1) and contains the material to be tested, means (2) (alternating potential source) to apply and to vary a potential supplied to a first terminal in the cell (1) via coupling means (7), means (8) to couple the second terminal in the cell (1) to the detection means which comprises a radio frequency amplifier (3), a rectifier (5), a d.c. amplifier (6).
In use, the alternating potential source (2) is held at a particular frequency thereby applying a potential to the first terminal and inducing a potential in the second terminal which provides an output signal in the detection means related to the composition of the material in the vessel (11). A change in the composition will change the impedance of the cell (1) and provide a change in the induced potential hence providing a variation in the output signal related to the change in the composition.
The apparatus shown in FIGURE 4 comprises the same features as that shown in FIGURE 3 with the additional feature of a reference signal input (9) into the radio frequency amplifier (3) from the alternating potential source (2) to provide a direct comparison of the amplitude of the potential applied to the first terminal with that of the induced potential. On substitution of the radio frequency amplifier (3) for a phase sensitive amplifier the phase of the second potential relative to the phase of the first potential may be measured.
The cell (1) shown in FIGURE 5 comprises a vessel (11), a first tubular terminal (12) in contact with the vessel (11), a second tubular terminal (13) in contact with the vessel, both terminals (12) and (13) having an arcuate inner face which conforms to the contours of the vessel (11), means (17) (barrier) to substantially prevent coupling of the terminals (12) and (13) other than through the zone bounded by the vessel (11) located between the first terminal (12) and the second terminal (13) and coupling means (7) and (8) for coupling the cell (1) to suitable circuitry.
The cell (1) shown in FIGURE 6 comprises the same features as that shown in FIGURE 5 with the additional features of an electrically earthed housing (15) enclosing the cell (1) and a block of insulating material (16) which is formed around a portion of the vessel (11), the terminals (12) and (13) and a part of the barrier (17) to provide a stable arrangement of those features.
A cell as shown in FIGURES 5 and 6 may be used in any suitable circuit as hereinbefore described especially in any of those shown in
FIGURES 1 to 4. The material to be analysed is passed through the vessel (11), a potential is applied to the first terminal (12) thus inducing a potential in the second terminal (13) which provides an electrical signal related to the composition of the material in the vessel (11), the induced electrical signal is then detected by the detection means.
The invention will now be illustrated by the following non-limiting examples.
Example 1 Frequency Resnonse of Different Topes of Snecies
Apparatus as illustrated in FIGURE 1 with a cell as illustrated in
FIGURE 6 was used to measure the resonant frequency of the circuit with different types of material present in the cell at 250C. All compounds used were of analytical grade.
The cell comprised a PTFE pipe of inside diameter 20 microns and outside diameter 1 millimetre, two tubular copper terminals having a length of about 0.5 cm and an internal diameter substantially equal to the outside diameter of the pipe, (the arcuate inner face of the terminals conforming to the contours of the vessel), located approximately one centimetre apart through which the pipe passed and an electrically earthed copper barrier located between the two terminals to act as an isolator all of which were set in a block of epoxy resin to provide a stable arrangement thereof.
This arrangement was located in a cuboidal die-cast steel electrically earthed housing of approximate dimensions 7cm x 4cm x 4cm having a port in each end face to allow the pipe to pass therethrough and a BNC insulated electrical connector located in each of two opposite sides of the housing to allow the terminals to be connected to the rest of the apparatus located outside the housing. The copper barrier was in contact with the housing.
Methanol was passed through the cell, the amplifier was switched on and the amplification factor was altered until a signal was detected.
This was achieved with an amplification factor of about 35 decibels. The circuit established its own resonant frequency which was dependent on the contents of the vessel.
Several compounds were passed through the cell and the resonant frequency of the circuit was measured for each compound. The results are shown in TABLE 1.
TABLE 1
Compound Resonance in MHz at 250C
Methanol 1.299
Ethanol 1.332
Propan-2-ol 1.349
Butan-l-ol 1.260
Acetone 1.318
Hexane 1.074
Dodecane 1.080
Tap water (River Tees) 0.861
Demineralised water 1.284
Purified demineralised water 1.288 (purity of 16 Asiemens) The results listed in TABLE 1 show that a wide variety of materials may be detected and distinguished on the basis of their effect on the resonant frequency of the circuit using the method of detection and apparatus of the invention.
Example 2 Detection of Concentrations of Species bv Frequency Response
The apparatus used in Example 1 was employed in this Example.
Solutions of sodium chloride in demineralised water and acetic acid in demineralised water of different concentration were passed through the cell (all percentages are weight percentages) and the resonant frequency of the circuit recorded. The results are shown in TABLE 2.
TABLE 2
Solution Resonance (MHz) at 250C
NaCl 1Z 0.495
NaCl 0.1Z 0.554
NaCl 0.01Z 0.857
NaCl 0.001Z 1.219
NaCl 0.0001Z 1.290
CH3C02H 1Z 0.646
CH3C02H 0.1Z 0.867
CH3C02H 0.01Z 0.983
CH3C02H 0.001Z 1.202
The results listed in TABLE 2 show that ionic and polar materials may be detected and that the concentration of a solution of the material may be determined over a wide concentration range on the basis of its effect on the resonant frequency of the circuit. The concentration of a material in solution may be determined by measuring the resonant frequency of solutions of the material of known concentration and plotting a calibration graph.
The resonant frequency of the unknown will then, from the graph, provide an indication of the concentration of the material in solution provided all other factors remain unchanged.
Example 3 Detection of Concentrations of Aqueous Methanol Solutions by
Amplitude Response
Apparatus as illustrated in FIGURE 3 was used to detect the concentration of the material present in the cell at 250C.
The cell used in the apparatus was similar to that illustrated in FIGURE 6.
Methanol was passed through the cell, the alternating potential source was switched on, the frequency was set at 1.299 MHz and the d.c. amplifier offset control was adjusted to give a reading of 0.000.
Several solutions of methanol in water were passed through the cell and the alternating potential was maintained at a constant frequency of 1.299
MHz. The output of the d.c. amplifier was recorded for each solution and the results are shown in TABLE 3.
TABLE 3
Solution Amplitude Response (millivolts) CH3OH 100X 0.0 (reference value) CH3OH 50.or 54.0 CH3OH 25.or 126.6 CH3OH 12.5Z 148.6 CH3OH 6.0t 160.0
Example 4
Detection of Concentrations of Aqueous Sodium Chloride Solutions bv Amplitude Response
The apparatus used in Example 3 was used to detect the concentration of the material present in the cell at 250C.
An aqueous solution of sodium chloride was passed through the cell, the alternating potential source was switched on, the frequency was set at 0.554 MHz.
Several aqueous sodium chloride solutions were passed through the cell and the alternating potential was maintained at a constant frequency of 0.554 MHz. The output of the d.c. amplifier was recorded for each solution and the results are shown in TABLE 4.
TABLE 4
Solution Amplitude Response (millivolts)
NaCl 0.1% 0.554
NaCl 0.01Z 0.417
NaCl 0.001% 0.202
NaCl 0.0001% -0.013
NaCl 0.00001% -0.033
Examples 3 and 4 show that the concentration of polar and ionic materials in solution may be determined on the basis of the energy transfer characteristics of the solution (amplitude being an indication of energy transfer) using the method and apparatus of the invention.
The concentration of a material in solution may be determined by measuring the amplitude response of solutions of the material of known concentration and plotting a calibration graph. The amplitude response of the unknown will then, from the graph, provide an indication of the concentration of the material in solution provided that all other factors are unchanged.
Claims (2)
1. Apparatus for the detection of changes in the composition of a material which comprises a first electrical terminal which, in use, is inductively coupled to a second electrical terminal through a zone to which a material to be tested can be introduced, means substantially to prevent inductive coupling of the terminals other than through the said zone, means to apply a potential to the first terminal, means to vary the said potential and means to detect, directly or indirectly, an electrical signal of the second terminal related to the composition of a material in the said zone.
2. Method of detection of changes in the composition of a material which comprises introducing the material to a zone between a first and second electrical terminal, applying a potential to the first terminal thereby inducing an electrical signal at the second terminal related to the composition of the material in the said zone and detecting, directly or indirectly, the electrical signal induced at the second terminal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9019980A GB2248301A (en) | 1990-09-12 | 1990-09-12 | Apparatus and method for the detection of changes in the composition of a material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9019980A GB2248301A (en) | 1990-09-12 | 1990-09-12 | Apparatus and method for the detection of changes in the composition of a material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9019980D0 GB9019980D0 (en) | 1990-10-24 |
| GB2248301A true GB2248301A (en) | 1992-04-01 |
Family
ID=10682114
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9019980A Withdrawn GB2248301A (en) | 1990-09-12 | 1990-09-12 | Apparatus and method for the detection of changes in the composition of a material |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2248301A (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1993018395A1 (en) * | 1992-03-10 | 1993-09-16 | Christopher Barnes | Apparatus for determining the physical and/or chemical properties of a sample, particularly of blood |
| US5583432A (en) * | 1994-04-11 | 1996-12-10 | Sci-Nostics Limited | Electrical method and apparatus for non-contact determination of physical and/or chemical properties of a sample, particularly of blood |
| WO1997032039A1 (en) * | 1996-02-29 | 1997-09-04 | Molecular Sensors Limited | Method for quantitative determination of a nucleic acid in solution by measurement of the electrical conductivity and apparatus therefor |
| WO1999010530A1 (en) * | 1997-08-22 | 1999-03-04 | Molecular Sensors Limited | Estimation of nucleic acid |
| WO2001059154A2 (en) * | 2000-02-08 | 2001-08-16 | Molecular Sensing Plc | Process for characterising nucleic acids in solution |
| US7128259B2 (en) | 2003-01-08 | 2006-10-31 | Ncr Corporation | Detector |
| WO2009124731A1 (en) * | 2008-04-10 | 2009-10-15 | Robert Seuffer Gmbh & Co. Kg | Method and device for determining a property of a dielectric medium |
| EP2708879A1 (en) * | 2012-09-14 | 2014-03-19 | Baumer Electric AG | Measuring assembly for determining a measuring capacity of a measuring sample |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1993018395A1 (en) * | 1992-03-10 | 1993-09-16 | Christopher Barnes | Apparatus for determining the physical and/or chemical properties of a sample, particularly of blood |
| US5583432A (en) * | 1994-04-11 | 1996-12-10 | Sci-Nostics Limited | Electrical method and apparatus for non-contact determination of physical and/or chemical properties of a sample, particularly of blood |
| WO1997032039A1 (en) * | 1996-02-29 | 1997-09-04 | Molecular Sensors Limited | Method for quantitative determination of a nucleic acid in solution by measurement of the electrical conductivity and apparatus therefor |
| WO1999010530A1 (en) * | 1997-08-22 | 1999-03-04 | Molecular Sensors Limited | Estimation of nucleic acid |
| WO2001059154A2 (en) * | 2000-02-08 | 2001-08-16 | Molecular Sensing Plc | Process for characterising nucleic acids in solution |
| WO2001059154A3 (en) * | 2000-02-08 | 2002-03-21 | Molecular Sensing Plc | Process for characterising nucleic acids in solution |
| US7128259B2 (en) | 2003-01-08 | 2006-10-31 | Ncr Corporation | Detector |
| WO2009124731A1 (en) * | 2008-04-10 | 2009-10-15 | Robert Seuffer Gmbh & Co. Kg | Method and device for determining a property of a dielectric medium |
| EP2708879A1 (en) * | 2012-09-14 | 2014-03-19 | Baumer Electric AG | Measuring assembly for determining a measuring capacity of a measuring sample |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9019980D0 (en) | 1990-10-24 |
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| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |