Detection device and method, and computer program for detecting a blood image parameter

Abstract

The present invention relates to a detecting device for detecting a blood count parameter in a blood vessel. The detecting device comprises a signal generator, which is designed to generate a calibration measurement signal, wherein the calibration measurement signal comprises a superimposition of a first excitation signal and a second excitation signal, wherein the first excitation signal has a higher frequency than the second excitation signal and/or the second excitation signal is a direct signal and/or wherein the second excitation signal has a higher power than the first excitation signal; a transceiver arrangement which is designed to emit the calibration measurement signal towards the blood vessel and to receive a first system response signal in response to the emission of the calibration signal; wherein the transceiver arrangement is designed to emit a third excitation signal directed towards the blood vessel and to receive a second system response signal in response to the emission of the third excitation signal; and a processor which is designed to link the first system response signal and the second system response signal in order to obtain a measurement signal for determining the blood count parameter.

Claims

1. A detecting device for detecting a blood count parameter in a blood vessel having: a signal generator which is designed to generate a calibration measurement signal, wherein the calibration measurement signal comprises a superimposition of a first excitation signal and a second excitation signal, wherein the first excitation signal has a higher frequency than the second excitation signal and/or the second excitation signal is a direct signal and/or wherein the second excitation signal has a higher power than the first excitation signal; a transceiver arrangement which is designed to emit the calibration measurement signal towards the blood vessel and to receive a first system response signal in response to the emission of the calibration signal; wherein the transceiver arrangement is designed to emit a third excitation signal directed towards the blood vessel and to receive a second system response signal in response to the emission of the third excitation signal; and a processor which is designed to link the first system response signal and the second system response signal in order to obtain a measurement signal for determining the blood count parameter.

2. The detecting device according to claim 1, wherein the transceiver arrangement comprises an antenna arrangement which is designed to emit the electromagnetic field of the calibration measurement signal or of the third excitation signal.

3. The detecting device according to claim 2, wherein the antenna arrangement comprises an electrical line arrangement or a semi-open waveguide, in particular a slotted waveguide, or a microstrip line.

4. The detecting device according to claim 1, with a bracelet, wherein at least the transceiver arrangement or the detecting device is integrated in the bracelet.

5. The detecting device according to claim 1, wherein the processor is designed to form a difference between the first system response signal and the second system response signal in order to obtain the measurement signal.

6. The detecting device according to claim 1, wherein the signal generator is designed to generate the first excitation signal as a small-signal and the second excitation signal as a large-signal.

7. The detecting device according to claim 1, wherein the signal generator is designed to generate the first excitation signal as a high-frequency signal and the second excitation signal as a low-frequency signal, in particular as a direct signal.

8. The detecting device according to claim 1, wherein the signal generator is designed to generate the first excitation signal with a frequency up to 100 GHz.

9. The detecting device according to claim 8, wherein the signal generator is designed to generate the first excitation signal with a frequency between 1 MHz to 100 GHz.

10. The detecting device according to claim 1, wherein the signal generator is designed to superimpose the first excitation signal on the second excitation signal to generate the calibration measurement signal.

11. The detecting device according to claim 1, wherein the transceiver arrangement is designed to detect the first system response signal and the second system response signal using an S-parameter measurement.

12. The detecting device according to claim 11, wherein the signal generator is designed to determine the first system response signal and the second system response signal based on a measurement of a forward transmission factor and/or on a measurement of an input reflection factor.

13. The detecting device according to claim 11, wherein the S-parameter measurement is a transmission measurement and/or a reflection measurement.

14. The detecting device according to claim 1, wherein the processor is designed to determine the blood count parameter based on the measurement signal.

15. The detecting device according to claim 1, wherein the processor or the transceiver arrangement is designed to determine a complex dielectric constant ε for the determination of the blood count parameter, wherein a real part ε′ of the complex dielectric constant ε substantially depicts a polarizability of a substance in the blood, and an imaginary part ε″ of the complex dielectric constant ε depicts its losses.

16. The detecting device according to claim 15, wherein the processor or the transceiver arrangement is designed to calculate a relaxation time constant (τ), for the determination of the blood count parameter, based on the formula: $τ = \frac{1}{2 π f_{A}},$ wherein f.sub.A denotes a relaxation frequency at which the imaginary part ε″ of the complex dielectric constant is maximal, and wherein the processor or the transceiver arrangement is designed to determine the blood count parameter depending on the determined relaxation time constant τ.

17. The detecting device according to claim 16, wherein the determined blood count parameter is a glucose concentration in the blood.

18. The detecting device according to any one of the claim 1, wherein the signal generator is designed to generate a clear signal for clearing a polarization of dipoles in the blood vessel caused by the calibration signal, wherein the transceiver arrangement is designed to emit the clear signal towards the blood vessel.

19. The detecting device according to claim 18, wherein the transceiver arrangement is designed to emit the clear signal prior to or after emitting the calibration measurement signal or after emitting the third excitation signal.

20. A method for detecting a blood count parameter in a blood vessel according to an embodiment, wherein the method encompasses the following steps: generating a calibration measurement signal, wherein the calibration measurement signal comprises a superimposition of a first excitation signal and a second excitation signal, wherein the first excitation signal has a higher frequency than the second excitation signal and/or wherein the second excitation signal is a direct signal and/or wherein the second excitation signal has a higher power than the first electrical excitation signal; emitting the calibration measurement signal towards the blood vessel; receiving a first system response signal in response to the emission of the calibration signal; emitting a third excitation signal in towards the blood vessel; receiving a second system response signal in response to the emission of the third excitation signal; linking the first system response signal and the second system response signal; and obtaining a measurement signal for determining the blood count parameter.

21. The method according to claim 20, wherein the method further encompasses the following step: emitting a clear signal prior to and/or after emitting the calibration measurement signal and/or after emitting the third excitation signal, for clearing a polarization of dipoles in the blood vessel.

22. A non-transitory digital storage medium with electronically readable control signals, configured for configuring a detecting device to a detecting device according to claim 1.

23. The non-transitory digital storage medium of claim 22 comprising a disk, CD, DVD, or EPROM.

24. A computer program product with a program code saved on a non-transitory machine-readable carrier for configuring a detecting device to a detecting device according to claim 1.

25. A non-transitory computer program with a program code for configuring a detecting device to a detecting device according to claim 1.

Description

DESCRIPTION OF THE FIGURES

(1) Further exemplary embodiments are explained in more detail with reference to the enclosed figures:

(2) FIG. 1 shows a schematic illustration of a detecting device for detecting a blood count parameter in a blood vessel according to an embodiment;

(3) FIG. 2 shows a schematic illustration of a detecting device for detecting a blood count parameter in a blood vessel according to an embodiment;

(4) FIG. 3a shows a schematic illustration of a reflection/transmission measurement for detecting a change of the electromagnetic field in a blood vessel by using a detecting device according to an embodiment;

(5) FIG. 3b shows a schematic illustration of a reflection/transmission measurement for detecting a change of the electromagnetic field in a blood vessel by using a detecting device according to an embodiment;

(6) FIG. 4 shows an S-parameter illustration of a coupling of an antenna arrangement or a line arrangement of a detecting device having a blood vessel according to an embodiment;

(7) FIG. 5 shows a diagram illustrating a real dielectric constant ε′ and a complex dielectric constant ε″ depending on a frequency determined by the detecting device according to an embodiment;

(8) FIG. 6 shows a schematic illustration of a method for detecting a blood count parameter in a blood vessel according to an embodiment; and

(9) FIG. 7 is a schematic illustration of a diagram for canceling a polarization of dipoles in a blood vessel caused by a calibration signal which is generated by a detecting device according to an embodiment.

DETAILED DESCRIPTION OF THE FIGURES

(10) In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which there is shown, by way of illustration, specific embodiments in which the invention may be embodied. It should be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the concept of the present invention. The following detailed description is therefore not to be understood in a limiting sense. Further, it should be understood that the features of the various embodiments described herein may be combined with each other unless specifically stated otherwise.

(11) Aspects and embodiments are described with reference to the drawings, wherein same reference numerals generally refer to the same elements. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects of the invention. However, it may be apparent to a person skilled in the art that one or more aspects or embodiments may be executed with a lesser degree of specific details. In other instances, well-known structures and elements are shown in schematic form to facilitate describing one or more aspects or embodiments. It is understood that other embodiments may be utilized and structural or logical changes may be made without departing from the concept of the present invention.

(12) Furthermore, while a particular feature or aspect of an embodiment may have been disclosed concerning only one of several implementations, such feature or aspect may be combined with one or several other features or aspects of the other implementations, as may be desirable and advantageous for a given or particular application. Furthermore, to the extent in which the expressions “contain”, “have”, “with” or other variants thereof are used in either the detailed description or in the claims, such terms should be included in a way similar to the expression “encompass”. The terms “coupled” and “connected” may have been used along with derivatives thereof. It should be understood that such terms are used to indicate that two elements cooperate or interact with each other, independent of whether they are in direct physical or electrical contact or are not in direct contact with each other. In addition, the term “exemplary” is to be considered as an example only and not as a designation for the best or the optimum. The following description is therefore not intended to be understood in a limiting sense.

(13) FIG. 1 shows a schematic illustration of a detecting device 100 for detecting a blood count parameter in a blood vessel 102 according to an embodiment.

(14) The detecting device 100 comprises a signal generator 104 which is designed to generate a calibration measurement signal, wherein the calibration measurement signal comprises a superimposition of a first electrical excitation signal and a second excitation signal, wherein the first electrical excitation signal has a higher frequency than the second excitation signal, and wherein the second excitation signal has a higher electrical power or capacity than the first electrical excitation signal.

(15) The detecting device 100 further comprises a transceiver arrangement 106 which is designed to emit the calibration measurement signal towards the blood vessel 102 and to receive a first system response signal in response to the emission of the calibration signal, wherein the transceiver arrangement 106 is designed to emit a third excitation signal towards the blood vessel 102 and to receive a second system response signal in response to the emission of the third excitation signal.

(16) Furthermore, the detecting device 100 comprises a processor 108 which is designed to link the first system response signal and the second system response signal in order to obtain a measurement signal for determining the blood count parameter.

(17) The signal generator 104 may be configured to generate the first electrical excitation signal as a small-signal and the second excitation signal as a large-signal. The large signal behavior of a “material under test” (MUT), e.g. of the blood, is not identical to the small-signal behavior. This happens because the small-signal, e.g. a microwave signal, can be superimposed by the large-signal. This large-signal could be e.g. a DC voltage or a DC field or a low-frequency alternating voltage or a low-frequency alternating field.

(18) With the superimposition of the large-signal and the small-signal, it is advantageously achieved that the calibration signal or a reference curve may be determined so that all insufficiencies and variations of the analog measuring circuit and the high-frequency (HF) lines are included. Therefore, a calibration compensates by the calibration signal, for example, variations in the analog circuit technique.

(19) Furthermore, by using the detecting device 100 according to the first aspect, for example, the technical advantage is achieved which is that a calibration measurement signal may be generated which requires no reference liquids, which may be generated shortly before the actual glucose measurement in the blood and which does not require any major interaction by the patient. Furthermore, therethrough the advantage is achieved that the measurement signal for determining the blood count parameter may be obtained non-invasively.

(20) FIG. 2 shows a schematic illustration of a detecting device 100 for detecting a blood count parameter in a blood vessel 102 according to an embodiment.

(21) In this embodiment of the detecting device 100, the signal generator 104 comprises a bias-T 112, which is designed to superimpose a large-signal of several volts on a weak small-signal, e.g. on a microwave signal in the mV range. The signal generator 104 may further comprise a switch 104a, wherein the switch 104a is configured to switch the superimposition of the large signal on or off. Furthermore, the detecting device 100 comprises two capacitors 110 and 110a, which operate in an AC circuit of the detecting device 100 as an AC resistance having a frequency-dependent impedance value.

(22) The switch 104a may further be configured to apply an alternating signal (AC).

(23) Further, the detecting device 100 may comprise an antenna arrangement (coupling arrangement) 200 which is attached to an arm 202 of the human body and that may be configured to focus the electromagnetic energy of the excitation signals in a vein 202a. In this embodiment, the antenna arrangement 200 comprises an electrical line arrangement 204, which may be designed as microstrip line, so that a line strip serves as exciter for coupling in microwave energy and another line strip as receiver for receiving the microwave energy. The antenna arrangement 200 may comprise a microstrip line being dielectrically loaded by the vein 202a, which microstrip line has two electric gates 114, 114a. The transceiver arrangement 106 may further comprise a network analyzer (NWA) 106a which is connected to the two electric gates 114, 114a and configured to measure the scattering parameters (S-parameters), i.e. to measure the wave size of the reflection (in particular a forward reflection factor S.sub.11) and the transmission (in particular a forward transmission factor S.sub.21) on electric gates 114, 114a as a function of the frequency.

(24) According to an embodiment, the electric line arrangement 204 comprises a length in the range of approximately 1 mm to approximately 20 mm. Reference measurements have shown that the longer the line is, the more accurate the blood pressure parameter can be determined. With long lines, more microwave energy may be coupled into the blood vessel, whereby the change of the electromagnetic field caused by the load by the blood vessel 102 is more pronounced. However, a compromise between the line length and the manageability of the electric line arrangement 204 should be made. For example, if the electrical line arrangement 204 is to be pressed onto the skin by a compression sleeve, the space for the electrical line arrangement 204 is limited. Furthermore, the blood vessels 102 do not always run straight through the body, so that for longer lengths, not the entire line length can act on the blood vessel 102. A length in a range of approximately 1 mm to approximately 20 mm or 30 mm has been found to be advantageous in terms of manageability. This also allows a good integrability in a bracelet.

(25) According to an embodiment, the microstrip line consists of a conductive strip which is separated from a conductive surface by a dielectric substrate. The microstrip line may consist of a non-conductive substrate or a printed circuit board, which is completely metallized on the underside, so that the metallization serves as a ground plane. On the upper side, a conductor in the form of a strip or a conductor track, i.e. with a defined conductor track width and conductor track length, can be arranged. This strip may usually be made by machining the top metallization by etching or milling. As substrate, various dielectrics, for example, glass fiber reinforced PTFE (polytetrafluoroethylene), alumina, or other ceramic material may be used. The signal radiated from the electric line arrangement 204 propagates on the one hand in the space between the strip conductor and the ground plane, on the other, the field lines also enter the free space above the strip conductor, which is usually filled with air, but in this case is formed by the blood vessel and its environment. A waveguide may be disposed over the strip line to excite the electric line arrangement 204.

(26) As already mentioned above, the microstrip line can consist of a non-conductive substrate, which is metallized on the underside and which has a conductor in the form of a strip on the upper side. The microwave energy emitted by the transceiver arrangement 106 propagates on the one hand in the space between the strip conductor and the metallization, on the other field lines enter also the free space over the strip line. By applying the strip conductor onto the skin, the microwave energy may emerge from the strip conductor via the field lines, enter the blood vessel 102 and couple back into the electrical line arrangement 204. As already mentioned above, the blood vessel 102 forms a resistance to the microwave energy, which loads the electrical line arrangement 204 and thus influences the arrangement of the field lines. Instead of a microwave line a slotted waveguide may be used, which causes the same effect, as described above. While microstrip lines are particularly suitable for use in the frequency range between a few hundred megahertz and about 20 gigahertz, waveguides are particularly suitable for use in the centimeter wave range and below, i.e. from about 3 GHz to about 200 GHz. At frequencies up to about 20 GHz, the microstrip line may thus be preferably used, which is simple and handy to manufacture, while for the use of frequencies above about 20 GHz, preferably a waveguide structure may be used, which allows a very precise measurement.

(27) According to an embodiment, the slotted waveguide comprises a rectangular waveguide having a plurality of circular slots or having one rectangular slot, in particular having a rectangular slot of 1 mm width and 20 mm length.

(28) Rectangular waveguides are particularly suitable for use in the centimeter wave range and below, i.e. from about 3 GHz to about 200 GHz, thus allowing a very accurate detection of the blood count parameter. As already explained above, reference measurements have shown that the longer the line is, the more accurate the blood count parameter may be determined. With slotted waveguides, these statements apply accordingly to the length of the slot through which the microwave energy is coupled out. With longer slots, more microwave energy can be coupled into the blood vessel 102, thereby the change in the electromagnetic field due to the load by the blood vessel is more pronounced. However, a compromise between slot length and manageability of the electrical line arrangement 204 should be made. Since waveguides can be very bulky, the slot length should preferably be limited. A length in a range of about 1 mm to about 20 or 30 mm has proven to be advantageous in terms of its manageability.

(29) According to an embodiment, the microstrip line comprises a coplanar microstrip line, in particular a ground-isolated coplanar microstrip line having a slot width in the range of about 0.1 mm to about 0.9 mm. Reference measurements have shown that the effect of the field change in this slot width range is particularly pronounced.

(30) According to an embodiment, the coupling of the electric line arrangement 204 to the blood vessel may be carried out by a non-invasive attaching of the electrical line arrangement 204 onto a skin surface of a human or animal body.

(31) Said attaching onto the skin surface may be a mere placing or positioning on the skin, for example, when using a thin microstrip line, which conforms to the unevenness of the skin surface. Preferably, however, a fastening device is used for attaching, in order to provide a suitable contact pressure, so that the measurements have the required accuracy. For example, a pressure sleeve may be used, as used in sphygmomanometers, to avoid an air gap. According to a design of the embodiment, the detecting device 100 comprises a bracelet attachable to an arm 202.

(32) The detecting device 100 may also be referred to as an in-situ detecting device because the detecting device 100 may remain on the body for both the determination of the calibration signal or the reference curve and for the determination of the measurement signal itself. There are no reference liquids necessary.

(33) There is hardly any time between the reference measurement and the actual measurement (in the dimension of a second). Thus, a drift of the analog circuit between the reference measurement and the actual measurement may be excluded.

(34) In addition, a further advantage is that it can also be assumed that the detecting device 100 does not slip between the reference measurement and the actual measurement. The antenna arrangement 200 sees the identical dielectric environment. Therefore, the detecting device 100 can, using the large signal, simultaneously eliminate variations in the glucose measurement due to a drift of the analog circuitry as well as due to a non-reproducible coupling to the body.

(35) Particularly the variation in the electromagnetic coupling to the body, since for example the bracelet slips again and again, represents a major problem. This is also solved by the detecting device 100. For this purpose, only a large signal in the form of a DC signal or a low-frequency AC signal is to be superimposed on the microwave signal for measuring the scattering parameters (typically 15, . . . , 25 GHz) via the Bias-T 112. The large signal is then to be switched on and off in order to switch between the measurement of the reference curve and the actual measurement.

(36) By the superimposed large signal, the calibration signal or a reference curve may be determined, in which all deficiencies and variations of the analog measuring circuit and of the high-frequency (RF) lines are included. This gives the advantage that the antenna arrangement 200 may be used on the body in the same way for both the small-signal and large-signal. Thus, the calibration compensates both variations in the analog circuit technology and in the coupling technology.

(37) FIG. 3a and FIG. 3b show a schematic illustration of a reflection measurement 300a/transmission measurement 300b for detecting a change in the electromagnetic field in a blood vessel 102 according to an embodiment.

(38) The blood vessel 102 can be characterized by a complex dielectric constant ε, wherein the real part ε′ of the complex dielectric constant ε essentially reflects the polarizability of a substance in the blood, and the imaginary part ε″ depicts the losses thereof. In particular, the real part ε′ of the complex dielectric constant ε describes the dielectric conductivity, also called permittivity or ε.sub.r2, of the blood vessel 102, since the dielectric constant ε is defined as the dimensionless ratio of the permittivity of the material to the permittivity of the vacuum.

(39) In addition to its dielectric conductivity ε.sub.r2, the blood vessel 102 may also be characterized by its magnetic conductivity μ.sub.r2. These parameters differ from the dielectric conductivity ε.sub.r1 and the magnetic conductivity μ.sub.r1 outside the blood vessel 102. Furthermore, the blood vessel 102 can be modeled as a two-gate and measured by the scattering parameter measurements.

(40) In the reflection measurement 300a, an incident wave a.sub.1 302a is emitted in the direction of the blood vessel 102 at the first port T1 114. When an electromagnetic wave a.sub.1 302a hits the wall of the blood vessel 102, the wave is reflected by the blood vessel 102 due to the differences between the electric and the magnetic conductivities and can be measured as a reflected wave b1 302b at the gate T1 114. There is no activity at gate T2 114a.

(41) In the transmission measurement 300b, the incident wave a.sub.1 302a is emitted in the direction of the blood vessel 102 at the first port T1 114. When an electromagnetic wave a.sub.1 302a hits the wall of the blood vessel 102, the wave is partially reflected by the blood vessel 102 due to differences in electrical and magnetic conductivities. Part of the energy is reflected as a reflected wave b.sub.1 302b at the gate T1 and can be measured there. A further part of the energy penetrates the blood vessel 102 and may be measured as transmitted wave b.sub.2 302c at gate T2 114a.

(42) In the modeling of the blood vessel 102 by a two-gate representation, the S-parameters include the elements S.sub.11, S.sub.12, S.sub.21 and S.sub.22:

(43) $(\begin{matrix} b_{1} \\ b_{2} \end{matrix}) = (\begin{matrix} S_{11} & S_{12} \\ S_{21} & S_{22} \end{matrix}) (\begin{matrix} a_{1} \\ a_{2} \end{matrix}) .$

(44) In this: a.sub.1 corresponds to the wave 302a entering at gate T1 114, a.sub.2 corresponds to the wave entering at gate T2 114a, b.sub.1 corresponds to the wave 302c leaving from the entrance (gate T1, 114) and b.sub.2 corresponds to the wave leaving from the exit (gate T2, 114a).

(45) The meaning of the elements S.sub.11, S.sub.12, S.sub.21 and S.sub.22 of the S-parameter is explained in detail in the following.

(46) The entrance reflection factor S.sub.11:

(47) $S_{11} = \frac{b_{1}}{a_{1}} {.Math.}_{a_{2} = 0}$
represents the reflection at the entrance without the wave impression at gate T1 114.

(48) The exit reflection factor S.sub.22:

(49) $S_{22} = \frac{b_{2}}{a_{2}} {.Math.}_{a_{1} = 0}$
represents the reflection at gate T2 114a without excitation at gate T1 114.

(50) The forward transmission factor S.sub.21:

(51) $S_{21} = \frac{b_{2}}{a_{1}} {.Math.}_{a_{2} = 0}$
represents the forward transmission without excitation at gate T2 114a.

(52) The backward transmission factor S.sub.12:

(53) $S_{12} = \frac{b_{1}}{a_{2}} {.Math.}_{a_{1} = 0}$
represents the backward transmission without excitation at gate T1 114.

(54) The network analyzer 106a shown in FIG. 2 may comprise a tunable oscillator in order to measure |S.sub.21|.

(55) According to a further exemplary embodiment, the accuracy in determining the loss values may be further increased by a further measurement of an amount of the measurement parameter of S.sub.11. The loss values may for example be determined based on the following formula:
P.sub.Verlust=1−|S.sub.11|.sup.2−|S.sub.21|.sup.2,
wherein P.sub.Verlust denotes each loss size, and wherein S.sub.11 denotes the entrance-reflection factor and S.sub.21 denotes the forward transmission factor.

(56) FIG. 4 shows an illustration of an S-parameter 400 of the coupling of the electrical line arrangement 204 having a blood vessel 102 according to an embodiment.

(57) In this, the electrical line arrangement 204 is excited with microwave energy at the two gates T1 114 and T2 114a. The transceiver arrangement 106 may be configured to excite the electrical line arrangement 204 and detect the change in the electromagnetic field by the gates T1 114 and T2 114a.

(58) The two impedances Z.sub.L.sub.1 left 402 and right 402a of the two gates T1 114 and T2 114a represent, for example, internal resistances of the transceiver arrangement 106 or of the detecting device 100, while the impedance Z.sub.L(ϵ.sub.r,MUT,μ.sub.r,MUT) between the two gates T1 114 and T2 114a denotes the wave resistance of the electrical line arrangement 204 which is loaded by the blood vessel 102. The blood vessel 102 is also specified here by the term “MUT, Material Under Test”. With the propagation of electromagnetic waves 408 on the electrical line arrangement 204, a reflection occurs at the end of the line when the circuit, being connected there, possesses an entrance impedance Z.sub.L(ε.sub.r2,μ.sub.r2) deviating from the value of the wave impedance Z.sub.L(ε.sub.r1,μ.sub.r1) of the unloaded electrical line arrangement 204. The ratio of the reflected voltage wave to the incoming voltage wave is referred to as reflection factor and is calculated according to the following equation:

(59) $r = \frac{{\overset{.fwdarw.}{E}}_{2 \tan}^{-}}{{\overset{.fwdarw.}{E}}_{1 \tan}^{+}} = \frac{Z_{2} (ϵ_{r 2}, μ_{r 2}) - Z_{1} (ϵ_{r 1}, μ_{r 1})}{Z_{2} (ϵ_{r 2}, μ_{r 2}) + Z_{1} (ϵ_{r 1}, μ_{r 1})},$
wherein:
Z.sub.L(ϵ.sub.r1,μ.sub.r1) corresponds to the wave impedance of the unloaded electric line arrangement 204;
Z.sub.L(ϵ.sub.r2,μ.sub.r2) corresponds to the entrance resistance of the blood vessel 102 coupled to the electrical line arrangement 204;
E.sub.1 tan: corresponds to the field strength of the incoming wave 302a; and
E.sub.2 tan: corresponds to the field strength of the outgoing wave 302b.

(60) For Z.sub.L(ε.sub.r2,μ.sub.r1)=Z.sub.L(ε.sub.r2, μ.sub.r2), the reflection factor becomes zero. This state is sought, since then the maximal power is transmitted and the resolution of measured values is greatest, in order to determine the blood count parameter. One speaks of impedance matching or power adjustment.

(61) FIG. 5 shows a diagram for illustrating a real dielectric constant ε′ and a complex dielectric constant ε″ depending on the frequency, which is determined by the detecting device 100, according to an embodiment.

(62) According to an embodiment, the processor 108 or the transceiver arrangement 106 is designed to determine a complex dielectric constant ε in order the blood count parameter, wherein the real part ε′ of the complex dielectric constant ε essentially depicts or reflects the polarizability of a substance in the blood, and the imaginary part ε″ depicts the losses thereof.

(63) Usually, relaxation phenomena in the dielectric spectroscopy on which the detecting device 100 is based are described by Cole-Cole relaxations. A Cole-Cole relaxation curve describes the complex dielectric constant:
ε=ε′+jε″
as a function of frequency. The Cole-Cole relaxation is a superposition of many Debye relaxations.

(64) As described above, the real part ε′ of the complex dielectric constant ε essentially depicts the polarizability of a substance and the imaginary part ε″ depicts the losses thereof. A relaxation frequency is associated with a maximum of the imaginary part ε″. At the same time, the real part ε′ drops by one step in the relaxation frequency f.sub.A. The behavior of the complex dielectric constant or dielectric constant ε is then accompanied by a maximum of the transmission loss of the scattering parameters. Thus, if one finds in the scattering parameter measurement a frequency at which high losses occur, then, one has found a relaxation frequency f.sub.A, since here the imaginary part ε″ is maximum. This increase in losses is also referred to in spectroscopy as a relaxation mechanism. The effect that can be used here is that the frequency at which the excess of losses—see local maximum of ε″—occurs, shifts with the concentration of the sugar content.

(65) For example, 80% of the human body is water. The water has a relaxation mechanism e.g. at about 20 GHz. Their detuning can be determined and depicted to the sugar content. The detuning of the resonance frequency f.sub.A at ε″ is easier to detect than the plateau change of ε′. In particular, variations in the coupling advantageously do not shift the frequency of the maximum of ε″. Thus, a determination of the sugar concentration from the observation of ε″ is much less error-prone than the observation of ε′ or of its level changes.

(66) However, the theory of the Cole-Cole relaxation is a linear theory, which means that the course of the complex dielectric constant ε″ as a function of the frequency is independent of the strength of the electromagnetic fields. In this case however, it is an approximation in the model. In reality, the course depends on the field strength and shows nonlinear behavior. In the case of the Cole-Cole model, as is customary in linearization methods, one assumes a small-signal modulation of the fields and thus nonlinear effects are ignored.

(67) The transceiver arrangement 106 may further be configured to determine a relaxation time constant τ of the blood count parameter depending on the frequency having the larger or the maximum loss value. Furthermore, the transceiver arrangement 106 may be configured to determine the blood count parameter, such as the glucose concentration in the blood, depending on the determined relaxation time constant τ.

(68) According to an embodiment, the transceiver arrangement 106 is particularly designed to calculate the relaxation time constant τ on the basis of the formula:

(69) $τ = \frac{1}{2 π f_{A}},$
wherein f.sub.A denotes the relaxation frequency, at which the determined loss value is maximum.

(70) Advantageously, then the transceiver arrangement 106 may be configured for determining the relaxation frequency, at which the imaginary part ε″ of the complex dielectric constant is maximum, and the relaxation time constant τ is to be determined depending on the determined frequency. The processor 108 may then use the determined relaxation frequency f.sub.A to determine the blood count parameter, for example the glucose concentration.

(71) FIG. 6 shows a schematic illustration of a method 600 for detecting a blood count parameter in a blood vessel 102 according to an embodiment.

(72) The method 600 encompasses the following steps:

(73) Generating 602 a calibration measurement signal, wherein the calibration measurement signal comprises a superimposition of a first electrical excitation signal and a second excitation signal, wherein the first electrical excitation signal has a higher frequency than the second excitation signal, and wherein the second excitation signal has a higher electrical power than the first electrical excitation signal;

(74) Emitting 604 the calibration measurement signal directed to the blood vessel (102);

(75) Receiving 606 a first system response signal in response to the emission 604 of the calibration signal;

(76) Emitting 608 a third excitation signal in the direction of the blood vessel 102;

(77) Receiving 610 a second system response signal in response to the emission 608 of the third excitation signal;

(78) Linking 612 the first system response signal and the second system response signal; and

(79) Obtaining 614 a measurement signal for determining the blood count parameter.

(80) According to an embodiment, the method 600 may encompass the following steps:

(81) Step 1: Placing the detecting device 100 on the body, e.g. an antenna arrangement 200 is disposed at the wrist on a vein lying close;

(82) Step 2: Determining a reference curve on the basis of a microwave measurement with superimposed large-signal. As a result, the relaxation is blocked/switched off;

(83) Step 3: Clearing the polarization, which was generated for example by a large-signal, by an alternating signal;

(84) Step 4: Measuring the actual microwave signal without large-signal;

(85) Step 5: Calculating the measurement signal by subtracting the reference curve of step 2 from the measurement curve of step 4;

(86) Step 6: Determining the maxima and minima in the transmission measurement and reading the relaxation frequencies; and

(87) Step 7: Converting the relaxation frequencies with knowledge of the temperature of the MUT to the glucose concentration.

(88) FIG. 7 shows a schematic illustration of a diagram for clearing polarization of dipoles in the blood vessel 102 caused by the calibration signal generated by the detecting device 100 according to an embodiment.

(89) According to an embodiment, the signal generator 104 is configured to generate the clear signal 700, in particular as a stationary or fading alternating signal. The transceiver arrangement 106 may be configured to emit the clear signal 700 in direction of the blood vessel 102. Furthermore, the transceiver arrangement 106 may be configured to emit the clear signal 700 prior to the emission of the calibration measurement signal or after the emission of the third excitation signal.

(90) FIG. 7 shows the behavior of the electric flux density D in the blood as a function of the electrical field strength E of a large-signal, e.g. a DC-signal.

(91) When the large-signal 706 is switched on, the electrical dipole moments of the MUT, e.g. of the blood in the blood vessel 102, are aligned in the electrical field generated by the large-signal. As the electrical field strength increases, more and more of these so-called electrical dipole moments align themselves parallel in the electrical field (electrical polarization). Due to the orientation itself, the external field is amplified. This leads to a strong increase in the electric flux density and in the electric field in the vicinity of the MUT. This process only takes place until all existing electrical dipole moments are aligned. As soon as this has happened, saturation is reached, as shown in FIG. 7 by a saturation point 704.

(92) According to an embodiment, the transceiver arrangement 106 designed to emit the third excitation signal in direction of the blood vessel 102 when the saturation point 704 is reached.

(93) Furthermore, the transceiver arrangement 106 may be configured to switch off 708 the large-signal after receiving the second system response signal. After switching off 708 the large-signal, the MUT may comprise residual effects of electrical polarization or remanence 712, i.e. switching on 706 or switching off 708 the large DC signal does not represent a perfect reversible process. Therefore, in order to cancel 714 the memory of the large DC signal or to disorder the order of the electrical dipole moments caused or brought or created by the large DC signal, the signal generator 104 may be designed to generate a subsiding signal or the clear signal 700. The deletion signal 700 may e.g. be an AC signal.

(94) The clearing of the identical orientation of the dipole moments in the blood vessel 102 corresponds to the origin 702 in the flux density D-E diagram, which is schematically connected to the saturation point 704 by a new curve 710.

(95) Furthermore, the transceiver arrangement 106 may be designed to emit the clear signal in the direction of the blood vessel 102 and to receive a system response signal in response to the emission of the clear signal 700.

(96) Further, the processor 108 may be designed to generate another calibration signal based on the system response signal. This additional calibration signal may correspond to a 0 dB reference curve, i.e. the reference curve is determined when no large-signal is present.

LIST OF REFERENCE NUMERALS

(97) 100 detecting device 102 blood vessel 104 signal generator 104a switch 106 transceiver arrangement or transmitter-receiver arrangement 106a network analyzer 108 processor 110 condenser or capacitor 110a condenser or capacitor 112 bias-T 114 gate 114a gate 200 antenna arrangement or array/coupling device 202 arm 202a vein 204 line arrangement 300a reflection measurement 300b transmission measurement 302a wave 302b wave 302c wave 400 illustration 402 impedance 402a impedance 408 waves 600 method 602 generating 604 emitting 606 receiving 608 emitting 610 receiving 612 linking 614 obtaining 700 clear signal 702 origin 704 saturation point 706 switch-on 708 switch-off 710 new curve 712 remanence 714 clear

Detection device and method, and computer program for detecting a blood image parameter

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Cpc classification

Classification Explorer

A61B5/145

HUMAN NECESSITIES

Classification Explorer

A61B5/6824

HUMAN NECESSITIES

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A61B5/14532

HUMAN NECESSITIES

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A61B5/681

HUMAN NECESSITIES

Classification Explorer

A61B5/7203

HUMAN NECESSITIES

Classification Explorer

A61B2560/0223

HUMAN NECESSITIES

Classification Explorer

A61B5/0507

HUMAN NECESSITIES

International classification

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A61B5/145

HUMAN NECESSITIES

Abstract

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