GB2260407A - Contactless measurement of physical parameters of samples - Google Patents

Abstract

Capacitative and inductive methods and apparatus for determining properties of liquids, particularly blood are described. Capacitative embodiments may comprise three electrodes 3, 4, 5, with the centre electrode earthed, arranged along a tube in which the sample may be static or flow. Preferably five electrodes are used as shown with two different AC frequencies (f1, f2) being fed to the first two electrodes 2, 3 and the output signals taken from electrodes 5, 6. An equivalent inductive embodiment (figure 3) uses two input coils fed with f1 and f2 respectively and two resonant output coils. Alternative circuits vary the frequency of a crystal oscillator (figure 4) or connect a tapped or linked coil in an in-line reflectometer or voltage standing wave meter circuit (figure 5). The cell may comprise two out concentric tubes (figure 5) and the apparatus may compare the sample with a reference sample (figure 9). If the sample is whole blood with suitable preservative, its physical or chemical state may be changed by external influence, e.g. addition of chemical or blood coagulant, by syringe, pipette or similar. <IMAGE>

Description

METHODS AND DEVICES FOR A.C. MEASUREMENTS ON ALL ELECTROMAGNETICALLY PERMEABLE MATTER, PREFERABLY LIQUID BLOOD.

This invention relates to four methods to ascertain certain physical and /or chemical properties of samples of electomagnetically permeable (electrically and/or magnetically permeable) matter of all types, states and phases, static or in transition,but preferably liquid whole blood or blood components, with or without suitable preservative and by use of single, double or multiple a.c. frequencies for excitation/ interogation without direct contact . "Properties of matter" includes the concept of detection of one phase or type of matter within another,e.g. biomass in water etc.

Most matter is electrically and magnetically permeable to varying extents, the property of which influences electric fields or the electric field vector of electromagnetic waves (radiation) is the permitivity or relative dielectric constant , while that with magnetic effect is the (magnetic) permeabilityo=.

Generally there are many more materials of lowland a range of , the so called dielectrics, then there are magnetic materials of high . In dielectrics laboratories, electrical properties of matter , especially liquids , are measured by bridge apparatus in which linear a.c. electric fields are employed and direct contact with metal electrodes is usually Inade. Alternatively time domain pulse reflectometry is employed where the sample is housed in a metal cavity to form the termination impedance of a coaxial feed-line.

These are standard techniques of so-called dielectric measurement. The parameters obtained by such measurement are the frequency dependent dielectric parameters E , "and tan 6 . These are often obtained for the sake of pure Scientific research. Alternatively they may be mathematically or empirically related to, or are indeed charactecised by, the physical and/or chemical state/properties of the sample.

For instance if the sample is a liquid containirlg particles in suspension , the size and number density of these may be hypothetically related to the dielectric parameters. In some liquids ,blood for example, the particle suspension is described as colloidal. The haematological parameters of blood are manifold and complicated, in brief being related to the chemical and biochemical composition of the blood electrolytes and plasma and to the sizes and number densities of red and white cells and to the electrical charge states of their membrane surfaces and walls.Properties of blood and other cells are traditionally determined by Coulter apparatus in which individual cells are manipulated into a counting/sizing gate which takes the form of a narrow orifice of micron sized dimension, manipulation and measurement often involving hydrodynamic focousing and the application of pulsed non-linear electric field gradients.

Coulter apparatus is extremely expensive, yet because of medical demand, is widely exploited. On the other hand a system not in current commercial exploitation is dielectric measurement of pathological blood samples to yield haematological paramaters . Although academics have attempted to assess the dielectric properties of blood in the laboratory , it would seem according to Scientific literature that they have always employed pooled samples of cells of various mammalian species separated into individual red and white fractions , often suspended in artificial electrolyte media and always in contact with metal and employing the standard techniques described above.

Although there is a moderate amouxlt of scientific literature on this type of approach , there is no really consistent agreement on the observed relaxation frequencies or mechanisms pertaining thereto. Indeed serious errors of measurement can be introduced in test vessels where a liquid sample is contained in contact with metal for the purpose of dielectric measurement due to electrical double layer formation and electrode polarisation at the liquid-metal interface and due to chemical reaction with agressive chemical media such as for example whole blood or blood fractions.

Recently some new but relatively simple methods have been described for applying fixed frequency non-contacting dielectric (capacitive) measurements to flowing solids, e.g. fly- ash, as in UK patent application GB 2 115 933A published on 14 September 1983. Similar techniques with vertically positioned essentially parallel external electrodes forming part of a resonant LC circuit have been applied to the case of flowing fluids e.g European patent application EP 0309 085 A2 , published 29th March 1989. However such simple capacitive techniques effectively only measure the electrical permitivity in simple form, ,and only at a single frequency and not in complex frequency dependent form as referred to above, where, #*(#) = #'(#) - j #'(#).

Because of this complex form, single frequency methods are strongly influenced by factors such as the D.C. ionic conductivity of liquid samples and/or the pos1ion(s) in frequency space , relative to the measurement frequency, of the dielectric loss maximum or maxima, and are thus not wholly satisfactory if a sample exhibits single or multiple dielectric dispersion It has also been recently recognised that the flow of electromagnetically permeable samples in tubes may be monitored by wrapping a non-contacting inductor around the tube and connecting it to essentially free running oscillator circuits, in such a way that either the self- resonant frequency of the inductor or resonant frequency of the inductor in series or parallel combination with a capacitor, crudely determines the oscillation frequency of the oscillator.

Alternatively some inventors have driven the cbil wit a.c. voltage in the region of parallel resonance and effectively measured the Q-curve by measuring the voltage across the coil . For dielectric samples,this procedure effectively measures non-complex ,single frequency permitivity by its effect of dielectric loading and lowering of the Q of the coil, thus the above restrictions of two capacitor plate methods also apply. Indeed some inventors have probably capitalised on these very restrictions themselves, with or without realising it , particularly with respect to low frequency dispersions or d.c. conductivity involving ionic conduction and device the use of these methods for detection of ion concentration in a liquid, see U.S. patent specification 4,590,424.

Similar inductive techniques have been applied to flowing particles where the predominant change in the coil is that of inductance rather than Q , the former being brought about by the particles' significant magnetic permeability rather than simply dielectric constant alone. The example is European patent application 0 157 496 A2, published 9/10/85. The present inventor sees these wholly free rujjtji ng methods of ocil.latiorl as adequate for the purposes for which they have been employed but idiot stable enough or sensitive enough for haematological purposes .A method confirring the stability of a quartz crystal or other high Q mechanical resonator on the non-contacting coil type of measurement will be described later below. A method which considers power reflection from such a coil will also be described.

The Inaterial which is of prime concern in this current rjpecification is of course blood which has the potenL ial to behave both as a dielectric and be magnetically permeable via the iron in the haemoglobin molecule. A U.K. patent specification GB 1 574 681 , granted to Labora Mannheim and published 10th September 1980 exists, concerning one haematological aspect, namely time-dependent erythrocyte sedinlerltation. It employs either two-electrode capacitive techniques or inductive LC techniques.Although a retuning mechanism is employed ill assessing the sedimen tat ion rate, the technique is still essentially a single freqency one, or at least the device operates within a single relatively narrow band of resonance frequencies about some mean which is not explicitly specified. As with academic literature , a recent search of patent literature seems to indicate that no attempts have been made to apply non-contacting dielectric methods for commercial exploitation in the haematological field for determination of standard haematological parameters other than time -dependent erythrocyte sedimentation rate. The other common hitherto dilectrically unexploited parameters such as cell number density ,size and haemoglobin concentration, are usually referred to as R.B.C. ,m.c.v.

and Hb respectively. The present inventor suggests that these restrictions on previous exploitation, could be due to the general limitations of single two plate capacitor and single inductor methods as outlined above, particularly with respect to finite variations found with pathological blood specimens in plasma and electrolyte conductivity and due to the multiple dielectric loss mechanisms and maxima to be expected as arising from blood cell size , shape and molecular motions of the haemoglobin molecule and other protein and other molecules haemoglobin molecule and other protein and other molecules present in such pathological blood samples.It will be appreciated by those with knowledge in these fields, that other fluids and materials both in vitro and in vivo could fall into this "restricted" category, i:e subject to the same or similar limitations.

According to the present invention there are provided alternative non-contacting, bridgeless methods which utilise concentric multi-electrode or multi-coil structures for capacitive and inductive measurement on samples of matter without contact together with the use of multiple-frequency excitations to separate out or reduce effects of ionic conductivity and/or multiple dielectric dispersion in samples, from any such dispersion or frequency region of interest, in order to yield physical or chemical properties of the sample*.

Thus if the sample is blood, use of the methods, measuring cells and devices associated with the present invention renders possible probably for the first time, by noncontacting dielectric techniques, measurement of haematological parameters other than time-dependent erythrocyte sedimentation.

* Includes presence of one phase of matter within another, e.g. biomass in water etc.

Further according to the present invention there are provided two single frequency inductive techniques, for non-contacting measurement on electrically and/or magnetically permeable samples. The first of these methods employs as an essential feature a quartz crystal in series with a coil. Thus it is the crystal frequency itself which is altered when a sample is inserted into or passed through the core of the coil, rather than that of a free running oscillator as used by previous inventors. Quartz crystal oscillators and variable crystal oscillators of which this technique is a hitherto unemployed variant, have both excellent amplitude and frequency stability, thus this technique is sensitive enough to measure changes as low as 1Hz due to subtle sample by sample differences or temporal variations in any one sample.

Furthermore, this technique should not be confused with that of the Fisher Scintific company, European patent application 0 309 085 A2 published 29/03/89, where a sample effectively tunes an LC circuit which forms the source load of a transconductance device (field-effect-transistor) and determines simply straight forward on-off oscillation of a quartz crystal depending on how close to parallel resonace is the parallel tuned LC circuit. Niether should it be confused with other techniques where a parallel LC circuit with the coil or capacitor surrounding the sample is signal fed with a fixed frequency crystal stabilised source, but where the voltage measurement is across the parallel tuned circuit after direct rectification, without or with the use of a differential reference as in United States patent no.

4,590,424.

The second single frequency method in this present invention employs a coil fed with power through a tap or link at resonance, subtle variations in the resonance causing subtle variations in the reflected power from the coil, which is easily measured by a reflectometer or voltage standing wave meter, provided with extra d.c. amplification if necessary.

Returnit o to the subject of erythrocyte sedimentation rate if) blood. This parameter , traditiollally measured manually in a period of 1 hour, depends on the surface electrical charge state of the cells and the amount of protein (mainly fibrinogen) in the surrounding plasma. The present inventor has found in private research that these parameters also influence the complex perlnitivity of blood samples instantly at certain frequencies with their precise weightitlg also depending on haemoglobin levels and varying from frequency to frequency.

Thus further according to this invention there is provided a device which employs either one frequency and external haemoglobin value exit ray or two appropriately chosen frequencies and internal compu tat ion to measure a new parameter that the present iiiventor chooses to call instant sedimentation rate, I.S.R.

A first specific embodiment of the inveitiori in relation to a group of measurement methods and noii-contactitig measurement cells for measurement on samples of all kinds of electromagnetically permeable matter is now described by way of reference to the accompanying drawing in which::- Figure 1 shows the three electrode measuring cell; Figure 2 shows the five electrode two frequency cell; Figure 3 shows the four coil ,two frequency inductive cell and method; Figure 4 shows the variable crystal oscillator measurement cell and method;and Figure 5 shows tile contactless continuous wave reflectometry cell and method capable of use at all radio frequencies.

Those skilled in the art will appreciate that the geometry of the receptacle cells described below can be altered to make them into probes which could be -pushed or dipped into the sample. Referring to the drawing , figure 1, three concentric electrodes 2-4 are arranged around ati iiisulating former and sample holder 1. Electrode 3 is grounded. Alternating current input is passed in through 2 and 1 to the sample and after interaction with the sample is passed back out in an attenuated form through 1 and 4. The grounded electrode 3 minimises stray capacity coupling between 2 and 4 along the outer surface of 1.Also the concentric arrangement is particularly suited to detecting temporal evolution of vertical zonal changes in the sample such as for instance precipitate formation or sedimentation. This is as distinct from the case of vertical planar or curved but essentially parallel electrodes as ucd by previous invel1tors where the received output signal is more likely to take oti the characteristics of a smoothed average as a function of time.

The three electrode cell shown is capable of use over a wide range of a.c. frequencies from a few tens of Hertz to several hundred Megahertz. A device employing such a cell will be described later below in a further embodiment of the invention.

An important variant of the three electrode cell is the five electrode two frequency cell shown iii figure 2, where 1 is again the former/sample holder and where 9-6 are again concerltric electrode strips or bands or rings.

Electrode 3 is grouiided. The advantage of providing five electrodes is that excitation of the sample can be made at two frequecies, f, and Fe simultaneously. Also that real-time tiathematical manipulation of detected voltages relating to f and 7 allows virtual eliminatioti of ionic conductivity effects and/or allows for the separation of information contained in one dielectric loss peak from that of another in frequency space on the basis of difference in slopes of the individual permitivity versus frequency, Q ,curves.As such, division of one respective voltage by tie other (after rectification) is often employed. Electrodes 4 and 6 are coupled to detectors to provide the rectification function. Even though due to capacitive and field strength considerations, a stronger element of voltage at frequency , should be present at electrode 4 and of frequency i at electrode 6 for fj close to tL , it is often necessary to employ high Q filtering between 4 and 6 and their respective detector circuitry.

Such filter may take the form of either quartz or other mechanical devices or LC circuits. The choice of two frequencies f, and factually employed and degree of filtering required, will be discussed in a later embodiment of this invention concerning devices. Furthermore in relation to this cell and method, it will be appreciated by those skilled in Electronics, that an alternative to simultaneous two frequency application and real time computation, is swept or sequentially stepped frequency application with sample and hold techniques being employed after the detectors and prior to mathelllatical processing.It will also be appreciated that the technique could be furthei extended by adding extra pairs of electrodes and extra frequencies,agairl applied either silnullaneously or sequentially. It would also be appreciated that the two frequency system will work with as well as without contact, by those skilled in the art.

Further within the embodiment on melhods and measuring cells, figure 3 is next referred to. This cell ad method essentially represents the inductive variant of the five electrode method just described. 1 now doubles as a coil former and holder for samples or samples in additional tubes.

7 and 8 are input link or coupling coils whose natural resonances lay well removed from the drive frequencies f, and fz and they are operated with one earthy end and driven by oscillators of both stable lrequelley and amplitude i:e crystal controlled or similar synthesis method 9 and 10 are the two output coils which are initially brought to a fixed high Q parallel resonai-ice lXy cdpaci tors fixed or variable , 11 atid 12 , at tlle two respective drive frequencies with either the sample holder empty or containing a calibrating electrolyte solution.The cell responds to permit ivity of samples or permeabl ity or both.

Introcluction of a sample, or sample Within a second insulating tube into 1 causes changes in the stray capacitance between all four coils, the Q of each coil and if the sample is magnetically active, i:e liars large permeability, then there will also be signifieant changes in the mutual coupling between the input and output coils. [3.C. output voltages are available for subsequent mathematical mallipulation , after the detectors, 13 and 14.This method is again applicable to a wide range of a.c. frqtiencies by appropriate selection of component values and those skilled in the field will appreciate that similar modifications to those suggested as feasible with lie five electrode cell in respect of number and type of frequency appli(:ation may also be possible in the case of the inductive variant.

Those skilled in the art will realise that can be frequency dependent as well as Also within this first embodiment, a new and very stable variable crystal oscillator single frequeticy method is shown in figure 4. Electromagnetically permeable samples cause changes in the coil,15, Q and/or mutual inductance, which in turn causes changes in the reactive loading on the quartz crystal 16 whose crystal oscillation frequency and output amplitude will vary slightly as a result, but whose stability will remain high allowing for much more refined atid accurate measurement than has hitherto proved possible with free running resonanceshift methods.Those skilled in electronics will appreciate that 16 may be replaced by any other form of high Q mechanical resonator or that coil 15 may be replaced by capacitor plates or that even a coil and capacitor plates may surround the sample simultaneously in series or parallel, this series or parallel combination itself standing in series or parallel with 16. Also they will appreciate that additional reactance not surrounding tiie sample may be introduced into the circuit between 15 and 16 so as to greatly enhance the frequency shift measured at the output of 17, however possibly with some sacrifice in overall frequency stability. To reiterate this method has the very great advantage that a high stability, close to that of an individual oscillating quartz crystal is confirred upon the measurement parameters.As mentioned earlier, it should not be confused with other techniques.

The final measurement method and cell in this first specific embodiment is that described by way of reference to Figure 5.

Where 1 is an insulating sample holder or tube and where 18 is a coil former of dimension suitable to take the tube 1 as a snug push fit. The r.f exciter 23 drives a signal through a reflectometer 22 and an optional coaxial link 21 into a lumptuned circuit consisting of linked or tapped inductor 19 and capacitor 20, the resonant characteristics of which are modified by the former 18 and addition of 1 with or without its sample. The degree of modification being greater when the sample is present. This modification is sensed by changes in the reflection or complex reflection coefficient at 22 which may be provided with an in-line offset or differential amplifier or both if the changes to be sensed are small or very small. Furthermore changes in reflection coefficient may then be mathematically or empirically related to to the properties of the sample in 1.

In relation to all the above methods and measuring cells in this first embodiment concerning such, the sample may be static or in motion, in vitro or in vivo, sedimenting or precipitating, or matter undergoing change of state or phase i:e physical and/or chemical reaction. In relation to the 5 electrode method in this embodiment, it is NOT to be confused with 4 point probe methods where current flows between two electrodes and voltage appears across the other two and where only one frequency or one swept frequency is employed.

A second specific embodiment of the invention now deals with measurement devices based on some, all or any of the aforegoing methods and cells. Whilst primarily these devices are suitable for use with whole blood in preservative, their use* for detection and measurement purposes with other dielectric and/or electromagnetically permeable samples is not ruled out. This embodiment is now further described by way of example with further reference to the accompanying drawing in which: - Figure 6 shows the block diagram of a device suitable for mean cell volume or haemoglobin calculation in blood samples.

Which of these two parameters is obtained depends on choice of cell structure 24 and precise choice of the two operating frequencies (see text); * footnote: for detection and measurement purposes.

Figure 7 shows the block diagram of a measurement device for I.S.R. calculation when the haemoglobin content of a blood sample is known in advance or alternatively it may be used to estimate a haemoglobin value when the traditional one hour erythrocyte sedimentation value is known in advance;and Figure 8 shows the block diagram of a device for simultaneous automatic haemoglobin and I.S.R. measurement, device can work without or with contact with blood.

Referring to the drawing, figure 6 shows how the cells and methods described previously with reference to figures 2 and 3 , may be employed to form a device to calculate without any contact, the erythrocyte mean cell volume,m.c.v., or haemoglobin concentration of a blood sample, preferably though not necessarily exclusively , within a citrated vacutainer. In the case of m.c.v. , vacutainer is inserted into orifice formed by former/measuring cell 24 which has four separate coils and works as described by method and figure 3 as it appears in the first embodiment above. In this case the specific frequencies chosen are f, =2.45MHz and for f; =1.742MHz, although other pairs of frequencies in the range 100 KHz -4 MHz are not ruled out. 25 and 26 are narrow band band-pass filters ,centred on f, and fz respectively.Detectors 13 and 14 feed a real-time computational circuit which performs a division function, f, /fX in turn driving an analogue or digital display module 28.

The blood m.c.v. value is outputed at this module. The would be constructor of such technology should be made aware that a relatively wide number of precise component options exist for all te structures in the block and so precise electronic circuitry and coil winding and filter data have not been provided explicitly. They should note also that initial calibration of such systems when designed and implemented from first principles is dependent on sequential insertion of a range of known pathological samples measured previously by another independent technique.

However once the device is built and working, other calibration media such as known electrolyte samples may be employed.

Those very skilled in electronics and microprocessor technology will realise that such a device lends itself for automation, self-checking routines and auto-calibration functions. The same is to be said of the other devices in this particular embodiment. Returning to the aspect of two frequencies, these are employed primarily in the case of blood m.c.v.

in order to eliminate d.c. conductivity effects which will be cancelled in the division function, as will tend also to be, all lower and higher frequency dispersions away from the one of interest ,i:e that closest f, and frown the basis of their lower slopes in terms of their own individual components of versus frequency relative to the mean frequency window established by fl and fi Furthermore in the m.c.v. case, the precise choice of fl and f and their window in frequency space specifically helps reduce contributions from the the higher low frequency haemoglobin dispersion ,the dielectric loss per wavelength of which at least for pathological blood samples in citrated vacutainers appears to peak in the region 5-15 MHz (established during private research of the present inventor).

In the case of using this device,figure 6, for haemoglobin calculation, similar principles to those established above for m.c.v. apply except the two frequencies fl and f; are chosen well beyond the m.c.v. dispersion and inbetween the l.f. and h.f. haemoglobin dispersions. In the specific case of the invention as currently constructed by the present inventor, frequencies of 28 MHz and 40 MHz are employed, but once again the choice of other nearby frequency pairs is not ruled out. Also for haemoglobin, 24 becomes the five electrode measuring cell. With 24 in this configuration, multipole quartz crystal or mechanical filters are best employed at 25 and 26 with pass frequencies of 28 MHz and 40 MHz .The haemoglobin value is then obtained by division of the d.c. signal from detctor/rectifier 14 by that equivalent d.c. signal from 13 in real-time computational circuit 27. The output may be either analogue or digital but included in the output module drive circuitry are range d.c. offset and gain/range expansion features in order that 28 can output Hb in internationally recognised units. Similar features in respect of gain and offset are also provided in the m.c.v case above. Those skilled in the art will appreciate that the 40/28 MHz two frequency system will also work with electrodes in contact with the blood if blocking capacitors are employed.

Haemoglobin can also be estimated in a simple manner without the use of two frequency methods/devices, if the traditional one hour erythrocyte sedimentation rate is known, this estimation is made by a device such as that outlined in figure 7, where the single frequency tree electrode measurement cell (figure 1 and aforegoing embodiment) is employed. Here the operation frequency is not too critical and most single frequencies in the range 40-200MHz may be employed. Operation is as follows:- the pathological sample in its vacutainer is inserted into the hollow former 1. The manually obtained erythrocyte sedimentation rate (E.S.R.) is entered into the device in numerical form by a scale calibrated knob affixed to the shaft of potentiometer 30 (this is shown as an analogue entry method ,but those skilled in Electronics will appreciate digital methods are not to be ruled out). The device then makes a differential calculation in 31 and the Hb is outputed in conventional form at the analog or digital display 28. The further background to these devices lies in private research of the present inventor , who has shown that the frequency dependent capacitance of blood in a vacutainer with citrate depends on fluctuating weightings of the E.S.R. and the haemoglobin concentration across the frequency range 20MHz to some 600MHz .The partial dependence on the E.S.R. is thought by the inventor to have its origins in the electrical charge state of the cell membranes, bulk and surface, the plasma conductivity and underlying plasma proteins particularly fibrinogen and any other snlaller molecules that may contribute to the sample dielectric loss in these frequency ranges. Consequently a simple device of the type outlined in figure 7 can effectively be used in reverse to provide an instant estimate of the E.S.R. or sedimentation state of the sample or more correctly to provide an output of the new parameter , described by the present inventor as the instant sedimentation rate or l.S.R.. It cannot be overstressed that this parameter is truly instant and that the speed of its appearance at the output depends only on the response time of the computational circuitry and output display device.In order to obtain the I.S.K. from a simple device such as that in figure 7 , 30 is arranged to accept entry of analogue Hb value, digital entry not ruled out, as obtained from someoutside source say for example from an optical lysis measurement.

31 and 28 are then arranged to output the I.S.R.voltage, which has no other units as such, but by appropriate scaling can be arranged to be made numerically similar both in absolute value and dynamic range of values for pathological states as per traditional E.S.R. values, particularly so for samples from healthy individuals or those with no significant haematological disturbances. Thus this simple device could find applications amongst others as a "good -health indicator" or for following the slow temporal progress of known pathological conditions of particular individuals, after first noting the " day one" I.S.R. starting value, of blood from a selected individual, progress then being monitored by taking new blood samples from the individual as often as requir,ed. Those skilled in the art will appreciate that the comments on making contact above also apply here.

Further reference to the drawing, figure 8, and noting all of the above, indicates that there is a device tat can calculate both Hb and I.S.R. simultaneously, without the need to extract data from other methods! In essence the bulk of the operation of this device is as that discussed earlier for Hb alone,i:e the device in figure 6.

The Hb is calculated in exactly the same way as before but may be electronically routed by switch 32a and 32b between either the display or a further differential circuit 33 which compares it with the d.c. voltage from the 40 MHz detector and thus produces an I.S.R. output in a manner not unlike that of the manual entry device above. The display 28 may be toggled freely between Hb and I.S.R., alternativelytwo simultaneous displays may be utilised. Those skilled in the art will appreciate the system can work by making contact as well as without contact.It will be appreciated by those skilled in the çrt that use of higher frequencies in the range 200 MHZ-10 GHz in relation to the above two embodiments is not ruled out, but obviously is technologically more challenging. All comments made in respect of elecronic variants to the cells and methods in the first embodiment of the invention also apply where those cells and methods are utilised in devices of the second embodiment.

The final specific embodiment of the present invention relates to use of the methods and devices in the first two specific embodiments in differential modes and to other specific haematological or medical or uses not adequately covered above. This final embodiment is now described by way of reference to the drawing in which: Figure 9 shows simplified block diagram of the differential mode; and Figure 10 shows essential additional accessory features for blood coagulation and/ or typing studies or for similar inducement of more general chemical reaction to be monitored.

Referring to the drawing , figure 9, the differential method is suitable for any system in which stirring a sample (reference) might highlight any differerices between this and an unstirred version, labelled "sample" in the figure. Such diffferences might be expected to occur as a result of physical or chemical reaction such as change of state or phase, sedimentation of suspendates in a liquid, formation of crystallites or precipitates from a liquid.or when one liquid contains biomass etc. Alternatively,the stirrer could be removed and the reference and sample cells held under different ambient physical conditions, as might be required to examine say the influence of temperature or pressure etc. upon a sample in real-time.In the operation of the system shown in figure 9, 34 is the sample container, 35 the test cell former, 36 is the former assembly, which although indicated as a single coil for simplicity, is in reality any of the former assemblies discussed in the first embodiment of this invention. 37 -is the whole of the measurement electronics associated with the sample and 38 is the whole of the measurement electronics associated with the reference. 37 and 38 are nominally identical units. Finally 39 is a difference amplifier, capable of driving an appropriate display.Those skilled in the art will appreciate that in vivo applications of this differential method may exist and be very useful, such as for instance assessing blood properties or blood flow whilst inside the digit(s) or limb(s) of any mammalian or of the human species ,where one or more limbs/digits is inserted into the core of 34, with or without tournequets being applied.

Again referring to the drawing ,figure 10 shows the essential accessory features required to bring about purposeful physical and /or chemical change in a sample by external (chemical)intervention. This technique may be applied to the aforegoing differential mode or to any of the measuring methods or devices referred to in the first two embodiments of the invention. In figure 10, 40 is a syringe, pipette or other suitable applicator, 41 is an open or sealed electrically insulating sample tube, glass or plastic etc.

and 42 is the chemical ,biochemical or biological sample.41 is inserted into the core or former of any of the aforegoing measurement cells or devices within the various embodiments of the present invention, for measurement at a fixed instant or as a function of time. A specific haematological use of the accessory as described is in coagulation clotting or blood typing operations where the agglutin etc. is injected directly into the sample by 40 whilst it were in situ and being electrically monitored.

Alternatively blood stasis , clotting and drying can be monitored without the use of preservative.

Furthermore those skilled in the art of biochemistry will appreciate that 40/41 could be arranged to contain enzyme -substrate or antibody-antigen components that may work in conjunction also with any pathological specimen or biofluid contained in either 40 or 41. Indeed they will further appreciate that 41 could contain a fixed ,sealed, preserved and predetermined quantity of bioreactant if necessary in a separate readily rupturable pouch,package, or vial , the contents of which are designed to spill out and mix with the biofluid in 42 or same biofluid or different biofluid injected by 40.Further they will appreciate that such bioreactant can he arranged to to be pre-adsorbed either physically or chemically bound to the walls of 41. The overall effect oi such bioreactions being by natural consequence or design , the release of ions or other dielectrically active entites or molecules, that can thus be detected without contact, or where the overall dielectric dispersion state of the bioreactive medium is altered in such a way that it can be detected without contact by multy frequency excitation methods outlined in earlier embodiments of this invention.

Finally it should he pointed out that there are probably many industrial and commercial processes other than medicine that can benefit from the new technologies disclosed in all three embodiments of this invention and that this invention is directly relevant to.

Claims (14)

1. Five methods and measuring cells for measuring certain physical and/or chemical (where physical includes certain electrical) properties of electromagnetically permeable matter, prefereably whole blood by a.c measurement without contact. Where the first such method employs a measuring cell with three electrodes, being concentric and arranged in line, with central electrode grounded.

Where the second such method and cell has similar electrodes but which are five in number, again with the central one earthed and where signal drive is applied to the top two at two distinct a.c frequencies and where attenuated signals are present at these frequencies after passage through the cell walls and sample and any additional sample container walls and where division of the detected received amplitude at one of these frequencies by that at the other can be used in order to home-in on any one specific dielectric loss peak in frequency space related to the sample in order to extract physical or chemical data concerning the sample that would not be possible using a single frequency technique and where such a sample exhibits single or multiple dielectric dispersion.Where the third method has two frequency excitation but is the inductive analog or variant of the second method and employs four coils or inductors, evenly or not evenly spaced and lying in line, where two of them form non-resonant input links and where the other two form resonant receiving coils, being brought to resonance by additional capacitors. Where the fourth method/cell controls the frequency of a variable crystal oscillator by means of inductance, capacitance or both and where the fifth and final method/cell employs a tapped or linked coil connected to an in-line reflectometer or voltage standing wave-meter. Where the methods/cells can also detect one phase within another, e.g. biomass in water. Where the cells could be made into probes.

2. Three methods for measurement as in Claim 1 above where the measurement methods and cells are those referred to as the third, fourth and fifth methods in Claim 1 above in that these are the methods containing inductive circuit elements and are thus able to respond to samples of electromagnetically permeable matter where magnetic permeability is an important feature, or will be expected to produce response over and above that due to the sample electrical permitivity. Where the methods/cells could detect one phase within another e.g biomass in water.

Where the cells could be made into probes.

3. A device based on the methods/cells in Claims 1 and/or 2 above to measure the mean cell volume (m.c.v.) of blood erythrocytes.

4. A device based on Claims 1 and/or 2 above to measure blood haemoglobin levels, knowing in advance the value of the erythrocyte sedimentation rate. Device can work with or without direct contact.

5. A device based on claims 1 and/or 2 above to measure blood haemoglobin levels without prior knowledge or other information. Device can work with or without direct contact.

6. A device similar to that in claim 5 but that can also measure and output a new haematological parameter referred to by the present inventor as the instant sedimentation rate or I.S.R. Device can work with or without direct contact.

7. A device similar to that in claim 4 except which measures the sample I.S.R. on the basis on externally entered information concerning the sample haemoglobin level, device operates in the megahertz frequency range, device can also be arranged for investigation of plasma proteins, device can work with or without direct contact.

8. Combined devices based on any of the devices referred to in claims 3 to 7, for haematological investigations.

9. Devices based on claim 1 for use with measurements of and/or detection of dielectric matter other than blood.

10. Devices based on claim 2 for use with measurements of an/or detection of magnetically permeable matter other than blood.

11. Devices based on claims 1-10 above which have any of the following uses/application areas; medical practice and/or research, and other commercial and industrial applications.

12. Devices as in claims 3-11, but that can operate in a differential mode, i:e pair of identical or near identical devices or measuring cells drives difference amplifier in order to extract data concerning or accentuating difference between two initially nominally identical samples, one stirred or otherwise exposed to different ambient physical and/or chemical conditions to the other so that temporal evolution of difference can be followed, as for instance in precipitate formation or sedimentation or crystallisation.

13. Devices as differential device in claim 12, specially adapted to operate with insertion of one or more mammalian (includes human) limbs or digits, with or without the use of applied tournequets, into core or cores of sample cells of devices in order to facilitate blood flow studies or check aspects of haematological condition of blood or condition of other bodily fluids without use of invasive technique.

Mammal in vivo.

14. Devices as in all claims 3-12 but where accessory apparatus such as a syringe/ pipette and/ or special sample tubes with coatings or sachets or easily broken vials etc. are employed in order to bring about physical change and/or chemical and/or biochemical reactions in the samples the products or progress of which can be monitored electrically and/or magnetically without contact by the devices. Examples of reactions of interest being blood stasis and clotting ,blood agglutination and typing and bioreaction such as enzyme-substrate or antibody-antigen and general chemical reactions of interest to industry.

14. Devices as in all claims 3-12 but where accessory apparatus such as a syringe/ pipette and/ or special sample tubes with coatings or sachets or easily broken vials etc. are employed in order to bring about physical change and/or chemical and/or biochemical reactions in the samples the products or progress of which can be monitored electrically and/or magnetically without contact by the devices. Examples of reactions of interest being blood stasis and clotting ,blood agglutination and typing and bioreaction such as enzyme-substrate or antibody-antigen and general chemical reactions of interest to industry.

Amendments to the claims have been filed as follows 1. A group of methods to ascertain certain physical and/or chemical properties of samples of electromagnetically permeable matter , preferably whole blood without contact and without the use of a bridge by utilising five different measuring cells in various configurations where the geometry of the cell is such that it usually forms a sample holding tube with orifice for sample entry, but where the cell can also form a probe; in either of these configurations the cell is usually in the form of an insulating former with various multi- electrode or inductor structures surrounding it , the form, number and structure of these structures being more thoroughly described below and where a. c frequencies in tlie k}iz to GHz range relay be applied through these structues to the sample within its orifice and where these frequencies are one, two or more than two in number , being simultaneously or sequentially applied in tile cases where they are more than one in number and where the first such measuring cell structure has three concentric electrodes surrounding it with the central one grounded to minimse stray capacity along the outer surface of the former atid through which a single frequency is applied to the upper electrode and received iri attenuated form at Ilie electrode furthest from tliis,after passages through tlie folder wall and a passage through tie sample;; the second form of measuring cell being a five electrode variant of the former, but where two frequencies are applied atid received sittiul taneously or sequentially to and from separate adjacent elect rode-s and wllere the specific advantage of two frequency excitation is in allowing real-time mathematical manipulation of the de tee ted received amplitudes at each frecuency after passage through the sample to allow for better separation of information contained iii otie dielectric loss peak when another may be very close it frequency space, atid/or to virtually eliminate ionic conductivity effects ; this technique being capable of extension by adding additional frequetic jes and electrode pairs one extra such pair for each extra frequency and wjiether extended or not, where high Q filtering plays an important role in the data recovery, and where the third measuring cell structure is an inductive analog of the five electrode cell also being used for two frequency application where four coaxial coils or inductors evenly or not evenly spaced along the former are employed in place of electrodes and where two of the four inductors form non-resonant input links to send the two frequencies itito the sample, each frequency sent in by a separate coil,and where the other two coils form resonant receiving coils to receive the two frequencies after passage through the sample, the resonance of these receiving coils being brought about by additional capacitors and where mathel latical manipulation takes place upon d.c. voltages obtained from detectors connected to the receiving coils, alternatively in order to form the fourth measuring cell structure , a single inductor is used or pair of capacitor plates or both in series or parallel , connecting to a variable crystal oscillator in order to control its output frequency and amplitude and the fifth and final cell structure has a single inductor which forms part of a resotiaiit lump-tuned circuit being linked or tapped and connected to an in-line ref lectome ter or voltage standing wavemeter through which an r.f. exciter drives in power via an optional coaxial link, furthermore, changes in the reflection coefficient are related mathematically or empirically to the propoerties of the sample in the cell.

2. A device based on claim 1 above to measure the mean cell volume (m.c.v.) of blood erythrocytes.

3. A device based on claim 1 above to measure blood haemoglobin levels , knowing in advance the erythrocyte sedimentation rate; device can also work with direct contact.

A A device based on claim 1 above to measure blood haemoglobin levels without prior knowledge of other inforination ,more than one measurement frequency being used; device can also work with direct contact.

5. A device also based on claim 1 but similar to that in claim 4 that in addition to haemoglobin concentration, can also output a new parameter referred to by the inventor as the instant sedimentation rate or I.S.R.; device can also work with contact.

6. Device based on principles of claim 1 that can output I.S.R.

if blood haemoglobin content is externally entered; device can also work with contact.

7. Combined devices based on one or more of the devices referred to in claims 2 to 6.

8. Devices for measurement of properties of and /or detection of electromagnetically permeable material other than blood, devices based on claim 1 above.

9. Devices based on claims 1 -8 above which have uses/application areas in medical practice ,research and other commercial and industrial applications.

10. Pairs of identical or near identical devices as in claims 2-9 operating in differential mode , i:e pair of identical or near identical measuring cells drive difference amplifier in order to extract data or accentuate difference between two samples 11. Devices as in claim 10 above specifically adapted to monitor non-invasively blood flow or condition, digit or limb etc. inserted into orifice of one or two sample holders.

12. Devices as in all claims 2-10 above but where accessory apparatus such as syringe/pippette and/o sample tubes with coatings or containing easily broken sacitets or vials etc; being employed to bring about physical or chemical and/or biochemical cahnge /reaction in sample (s) the products and/or progress of which being monitored by the devices, examples of such reactions being blood stasis alld clotting, blood agglutination and typing , bioreaction such as enzyme substrate or antibody -antigerl types and general chemical and physical reactions of interest to industry.

13. Devices as differential device in claim 12 ,specially adapted to operate with insertion of one or more mammalian (includes human) limbs or digits, with or without the use of applied tournequets , into core or cores of sample cells of devices in order to facilitate blood flow studies or check aspects of haematological condition of blood or condition of other bodily fluids without use of invasive technique.

Mammal in vivo.