DE4314835A1 - Method and device for analysing glucose in a biological matrix - Google Patents

Abstract

Method for determining the concentration of glucose in a biological matrix, comprising at least two detection measurements, in each of which light is injected into the biological matrix as primary light, the light is propagated in the biological matrix along a light path and a light intensity emerging as secondary light is measured, and an evaluation step in which the glucose concentration is derived from the measured intensity values of the detection measurements by means of an evaluation algorithm and a calibration. Good analysis accuracy is achieved with simple means in that a first detection measurement is a spatially resolved scattered-light measurement, in which the primary light is injected at a defined injection location into the biological matrix, the intensity of the secondary light emerging from the biological matrix at a defined detection location is measured and the detection location is arranged relative to the injection location such that light multiply scattered at scattering centres in the biological matrix is detected, the intensity of which light is characteristic of the concentration of glucose, and the light path is different in a second detection measurement from that in the first detection measurement.

Description

The invention relates to a method and a device for the analysis of glucose in a biological matrix.

The term "biological matrix" refers to a body liquid or tissue of a living organism. Biological matrices to which the invention relates are optically heterogeneous, i. H. they contain a variety from scattering centers, where irradiated light is scattered becomes. In the case of biological tissue, in particular Skin tissues become the scattering centers of the cell walls and other components contained in the fabric forms.

Body fluids, especially blood, are also a problem heterogeneous biological matrix because they ent particles hold on which the primary radiation is widely scattered becomes. Milk and others in food chemistry too investigating liquids often contain a high level  Concentration of scattering centers, for example in form of emulsified fat droplets.

For qualitative and quantitative analytical determinations components of such biological matrices generally reagents or reagent systems sets, their reaction with the respective component a physically detectable change, for example a change in the color of the reaction solution that can be measured as a measurand. By calibration with Standard samples of known concentration become a correla tion between those at different concentrations measured values of the measurand and the respective concentrations tration determined.

Although these methods enable high-Ge analyzes accuracy and sensitivity, however, make it necessary Lich, a liquid sample, especially a blood sample to be taken from the body for analysis ("invasive analysis"). This sampling is uncomfortable and painful leads to a certain risk of infection.

This is especially true if an illness is very common Requires analysis. Probably the most important example is diabetes. To serious complications and critical Avoiding the patient's This disease requires the blood's glucose content to be determined very frequently or even continuously.

There are therefore a large number of processes and Devices have been proposed to reduce glucose in blood, Tissues or other biological matrices in vivo and to be determined non-invasively.  

The invention relates to a subset of such Processes in which light passes through the biological Ma trix limiting interface as primary light in the bio logical matrix is irradiated, and the intensity of the after interaction with the biological matrix from the ser is measured as secondary light emerging light. Such a measurement is referred to here as a "detection measurement" draws. Often used to determine a glucose concentration of several detection measurements, mostly at un different wavelengths. From the at the intensity measurements determined using the detection measurements a measurand of the secondary light is derived, the (without using reagents) a measure of the concentration tration of the analyte in the biological matrix. The Wavelengths of light that are discu are generally between about 300 nm and several thousand nm, i.e. in the spectral range between the near UV and infrared light. The term "light" is allowed not as a limitation to the visible spectrum be understood in the realm of light.

An overview of physicochemical (reagent-free) Determinations of glucose in vivo are given in: J.D. Kruse-Jarres "Physicochemical Determinations of Glucose in vivo ", J. Clin. Chem. Clin. Biochem. 26 (1988), 201-208. As a non-invasive procedure among other things the nuclear magnetic resonance (NMR, nuclear magnetic resonance), electron spin resonance (ESR, electron spin resonance) and infrared spectroscopy called. However, none of these procedures have so far can gain practical importance. Are partial extremely large and complex equipment required for routine analysis or even the self-control of the Patients (home monitoring) are completely unsuitable. in the Case with the analysis of glucose and other analytes  IR spectroscopy is used to measure the accuracy solution - even when monitoring progress over a relatively short period Periods - at the current state of development and sufficient. This is likely due to the numerous Disturbances due to absorbing foreign substances to be led.

The invention has for its object a method for the analytical determination of glucose in a bio to provide a logical matrix, which with simple means, reagent-free and non-invasive works and good analytical accuracy, for example for monitoring the change in analyte concentration (Follow-up) over a sufficient period of time possible.

The task is solved by a procedure for determining measurement of the concentration of glucose in a biological Matrix, comprising at least two detection measurements, each of which has light through a biological matrix limiting interface as primary light in the biolo The matrix is irradiated, the light in the biolo propagated matrix along a light path and a from the biological matrix by limiting it Interface emerging as the light intensity emerging from secondary light is measured, and an evaluation step in which the Intensity measurements of the detection measurements using an evaluation algorithm and a calibration the Glu cos concentration is derived, at which a first Detection measurement a spatially resolving scattered light measurement is, in which the primary light at a defined on radiation site irradiated into the biological matrix will, the intensity of the detection at a defined location secondary emerging from the biological matrix light is measured and the detection location relative to that  Irradiation site is arranged so that at scattering centers light scattered by the biological matrix tiert, whose intensity for the concentration of Glucose is characteristic, and the light path at one second detection measurement from that of the first detection measurement is different.

The invention further relates to a device to determine the concentration of glucose in a biological matrix, in particular to carry out the Method according to one of the preceding claims, with one for application to an interface of the biological Matrix provided light transmission area, single beam agents for irradiating light into the biological Matrix through an interface that delimits this, Detekti on means for measuring the intensity of from the biolo matic matrix through an interface that delimits this emerging light and evaluation means for converting the measured intensity in one of the glucose concentration corresponding signal in which the irradiation with tel for the targeted lighting of a defined single beam Are trained location and the detection means for targeted measurement of the at a defined detection location emerging secondary light are formed, the Detection location so arranged relative to the irradiation location net is that at scattering centers of the biological matrix scattered light is detected, its intensity characteristic of the concentration of glucose is.

An essential feature of the invention is that the Measurement of the secondary light with at least one detective onsection not on a beam direction or a win kelbereich of the passing through the measurement object Light or the light reflected from the measurement object  relates, but to a defined sub-area of a the boundary delimiting the biological matrix, called Detection site is called. The radiation of the Primary light occurs in a defined area ei ner interface of the biological matrix, which as an radiation location is designated. Such a measurement will referred to as "spatially resolving detection measurement".

The terms "irradiation site" and "detection site" are (roughly in the sense of the English term "site") geome to understand trically, namely as the geometric place the light rays that are present in the respective detection measurement are determining for the intensity measurement, by an interface bounding the biological matrix step through. As a collective term for the place of entry and the detection site is therefore also the Be drawing "place of passage" used.

As far as below information about distances between through steps are made, they relate to each other to the center of the irradiation site or the detection location. The center is in a circular design from the center, with an elongated design of the center line, it being assumed that elongated detection sites in uniform intervals stood from the respective irradiation location, d. H. their center line runs at an even distance from the Center point or the center line of the respective irradiation location.

It is also essential for the invention that at least at least one of the detection measurements, its intensity Use measured values to determine the glucose concentration the places of passage (i.e. the irradiation location and the detection location) relative to each other  are net that at scattering centers of the biological matrix scattered light is detected, its intensity characteristic of the concentration of glucose is. To guarantee this "multiple scatter condition" The following should be taken into account.

The mean free path of photons in tissue or the body fluids mentioned is of the wavelength and the respective density of the existing scattering centers dependent. It is typically between about 0.01 mm and 0.1 mm. On the light path in the biological matrix from the radiation site to the detection site at least about 10, preferably at least about 100 Scattering processes take place. The light path within the biological matrix is always longer (in many cases even it considerably longer) than the direct connection between on radiation location and detection location. As a practical rule However, it can be stated that the distance between A Radiation site and detection site of at least the ten times, preferably twenty times, especially be preferably 50 times the mean free path of the Photons in the respective biological matrix at the correspond to the respective wavelength of the primary light should.

The maximum distance between the radiation site and the detection site is also from the middle free one Path length depends on the photons. Above one in single If the limit to be determined experimentally is dependent accuracy of the measured intensity of the glucose concentrations tration back so that the signal / noise ratio gets bad. Preferably the distance between Radiation site and detection site less than 25 mm, be preferably less than 15 mm. To exclusively Scattering centers of the biological matrix widely scattered  To capture light must also be careful Shielding the primary light from the detector with which the secondary light is measured.

The multiple scattering leads to that at the detection site emerging light has a largely diffuse character, d. H. its intensity is largely independent of the end step angle at which it is detected. If that's primary is light coherent and / or polarized, these go Properties lost due to multiple scattering. Also this can be used to test whether the required for the invention Such "multiple scatter condition" is met.

It is clear that the Ge viewpoints "spatially resolving detection measurement" and "Multiple scatter condition" are linked together. A detection measurement in which both characteristics are met are, as "spatially resolving scattered light measurement" be draws.

The spatially resolving litter is preferably located light measurement of the detection site at the same interface che like the irradiation site, d. H. it becomes "in reflection" measured. So far two opposite borders areas of the biological matrix are accessible but can also be measured "in transmission", whereby the irradiation site and the detection site on opposite lying interfaces of the biological matrix. The terms "transmission" and "reflection" with regard to the diffuse character of the detec location of the emerging light is of course not so understood that the secondary light with a strong domi preferred direction emerges from the matrix.  

The radiation site and the detection site can be at spatially resolving scattered light measurement very different Have dimensions and geometrical shapes. Essential Lich is only that by the spatially resolving scattered light information about the intensity of the secondary depending on the relative position of the Irradiation site and the detection site (not in Dependence on the detection angle) is obtained. Several such spatially resolving scattered light measurements, in which the respective detection location a different Ab has stood from the respective irradiation location information I (r) about the functional dependency the intensity I from the distance r.

In the preferred case the reflection measurement is located the detection site is preferably in a detection area that includes the portion of the interface that a distance of at least 0.2 mm and at most 25 mm from the center of the irradiation site. in case of an point or circular irradiation site is the De tection area in which the detection location is located a circular ring with an inner diameter of 0.2 mm and an outer diameter of 25 mm. In the event of of an elongated irradiation site defines the The above condition as the detection area is the on closed ring area surrounding the radiation site with a shape deviating from the circular shape.

In the most general case, the irradiation location and before especially the detection location with the spatially resolving litter light measurement have relatively large dimensions. In the event of the reflection measurement, for example, the entire De tection area with a spatially resolving scattered light measurement solution can be detected as a detection location. The quality of the However, spatial resolution is improved if the through  place of kick in the direction of the respective irradiation location and detection location connecting distance a ver relatively small dimension, preferably less have than 2 mm, particularly preferably less than 1 mm. In particular, the places of passage (in particular the Detection location) advantageously elongated and narrow be educated. Such a place of passage is called a through entry field (radiation field or detection field) draws. The smaller dimension of a passage area is preferably less than 2 mm, especially before pulls less than 1 mm.

In the invention, the intensity measurements of min least two detection measurements used to in one Evaluation step of the method by means of an evaluation al gorithmus and a calibration the glucose concentration to determine ("to derive"). At least a first one of these Detection measurements must have a spatially resolving scattered light be measurement. A second detection measurement can in principle, another method is also used the. However, at least two are particularly preferred spatially resolving scattered light measurements carried out from de the intensity measured the glucose concentration is leading.

The at least two detection measurements are preferably carried out solutions simultaneously or in a sufficiently short time Distance. A temporal is considered to be sufficiently short Understand the distance at which between the measurements that to derive a concentration value of glucose ver be used, none impairing the measuring accuracy Change in the biological matrix takes place. Appara tiv this is preferably realized in that switchable radiation means and / or detection means are provided to adjust without moving parts  different pairs of passageways chen.

In any case, it is important that the light path of the sufficiently differentiates the detection measurements. At two spatially resolving scattered light measurements, this Be condition preferably by different measuring distances between the respective radiation site and the respective guaranteed location of detection. Preferably different which the measuring distances are preferred by at least 30% at least 50%, particularly preferably at least 70% of the shorter distance between the irradiation site and the detective onsort.

Different measuring distances between the respective on leave the radiation location and the respective detection location can be practically realized in different ways. Preferably, the radiation is kept constant location of the assigned detection location varies. It is however also possible with a constant detection location by varying the irradiation location to form pairs of passageways or both Vary detection location as well as the irradiation location.

However, a different light path cannot only be done a different length of the measuring distance results ren. It is also possible that the radiation location and the location of detection so that their Distances in the two detection measurements are the same are the tissue structures on the two light paths themselves but clearly differentiate.

With a spatially resolving scattered light measurement, the Be grabbed "Lichtweg" because of the multiple scatter in the biolo of course not a geometric matrix  strictly limited partial volume of the biological matrix (as with a classic transmission spectroscopy ei ner non-scattering liquid in a cuvette) stand. Nevertheless, it makes sense to use the term "light path" to use, for example as that part volume of the biological matrix can be understood in which a certain percentage (e.g. 70%) based on a specific irradiation location arriving at a certain detection location, in the Ma trix light that is widely scattered.

For the purposes of the present invention, the Condition that the light paths of the two become determinants Detection measurements used to measure the concentration must distinguish sufficiently strongly, defi kidneys that the dependence of the intensity I of the gemes its secondary light from the glucose concentration C. the two detection measurements are not linear with each other may be knotted. In other words, the two may Functions I₁ (C) and I₂ (C) for the two difference light paths are not linearly dependent on one another. The one caused by the different light paths Difference in intensity of the secondary light (related to an equal area of the detection site and with the same intensity of the incident primary light) should be at least a factor of 3, preferably at least a factor of 5, particularly preferably at least one factor identify gate 10.

It is characteristic of the invention that one for the Glucose concentration characteristic measured variable without measurement solution of several wavelengths can only be determined by this can that two detection measurements (with preferential same measuring wavelength) with different light paths take place with at least one of the detection measurements  is a spatially resolving scattered light measurement. In the opposite sentence on known spectroscopic methods (ins special NIR spectroscopy) is not the point the optical absorption to be a measure of the glucose vote. The wavelength is preferably even in one Spectral range chosen in which the absorption of the Glucose is relatively low. Those are preferred Wavebands between about 750 and 825 nm and between between 1150 and 1350 nm.

The primary light should preferably be monochromatic. "Monochromatic" is here in a practical sense to understand that the majority of the Intensi emitted in a relatively narrow wavelength range becomes. The full width at half maximum should be less than 100 nm preferably less than 20 nm and particularly preferably less than 5 nm.

It is sufficient if the at least two detection measurements at a single wavelength leads. Have within the range mentioned wavelengths between 800 and 805 nm are special proven suitable. This can be attributed to that HbO₂ and Hb be an isosbestic point at 802 nm sit at which the measured intensity is independent of is the ratio of Hb to HbO₂. This also applies in egg wide isosbestic range between 1200 and 1300 nm. In addition, the absorption is in this range of hemoglobin and water about the same size. Thereby he there is a better independence of the measured In intensity of the ratio of Hb, HbO₂ and H₂O.

Although measurements at one wavelength are sufficient, it will of course be useful for others to measure additional wavelengths, in particular in order to  To be able to eliminate disturbances better. About this sturgeon sizes include possible changes in the Scattering centers, as well as water absorption and Hemoglobin absorption, which in turn is directly affected by the blood volume in the examined biological matrix depends. This is related to the fact that the intensity of the secondary light from the blood pulse and the Body temperature is affected. Let these influences control yourself. With regard to the blood pulse, ent neither over a sufficient number of pulse periods averaged or pulse-synchronous. The variation body temperature can be recorded and used to compensate tion can be used. Alternatively, the detection area empire in which the passage fields are located thermostated. Because with such a temperature control a relatively high energy consumption is connected in a preferred device within the scope of the invention for in-vivo analysis of the measuring range carefully thermal isolated.

According to the current state of knowledge, the inventor lets the effect on which the invention is based, such as explain as follows.

The change in the glucose concentration leads to a change change in the refractive index of the in the biological matrix contained liquid in which the glucose is dissolved. The change in the refractive index leads to a change the light scatter on the scatter contained in the matrix centers. However, this change is for each individual scattering process extremely small. Calculations have shown that the change in refractive index per mmol is only about Is 0.002%. In the context of the invention was festge makes this extremely small effect for analysis of glucose can be used practically if you have the Streupro  Processes of many photons that are similar to one another ha light path in the biological matrix ben, recorded. It has been found that this can be done with the help of the spatially resolving scattered light measurement is possible.

In the invention, the measuring method is thus designed that ideally the scatter dependent on the refractive index behavior of the space surrounding the scattering centers half of the biological matrix is determined. As part of the Invention, it has been found that this mechanism is very is sensitive, d. H. the measured signals at ver relatively small changes in glucose concentration change greatly. An essential characteristic of the Er invention is that the at a suitable Detek location under the conditions of spatially resolving litter light measurement measured change in the intensity of the second därlichts with a defined change in glucose concentration much larger than with an absorption measurement solution.

The absorption of glucose in human tissue is at Waves applicable in the context of the present invention length very small. It can be quantitatively estimated that for the change in the intensity attributable to absorption I per glucose concentration unit in the wavelength range from 700 to 2000 nm applies:

dI / dC 10 ^-5 dl / mg.

In other words, the change when the glucose concentration changes by 100 mg / dl is only about 10 ^-3 absorption units.

In the present invention, for example, a change in the concentration of glucose from 5 mmol / l to approximately 20 mmol / l intensity changes in the secondary light was observed with a spatially resolving scattered light measurement of approximately 20%. This corresponds to a value for dI / dC of more than 10 ^-2 . This astonishing effect can be explained by the multiple scattering which is made available for the analysis of glucose in the context of the present invention. The measurement technique according to the invention can therefore also be referred to as multiple scatter amplified glucose detection (MSAGD). It is characteristic of the invention that the change in the intensity dI / dC of the secondary light in a spatially resolved scattered light measurement according to the invention is at least ten times, preferably at least 50 times as large as the dI / dC value when the absorption is only taken into account.

Distinguished by the need for multiple scattering the MSAGD is fundamentally different from the previous approaches for non-invasive analysis. Especially with infrared spectroscopy based on the measurement of the wavelengths dependence of the absorption is based on the optical Scattering is bothersome. As a result, after Possibility body parts selected that one if possible cause little scattering of light. For example has been proposed to make NIR spectroscopic determinations the antechamber of the eye to perform a ver relatively clear and therefore non-scattering liquid contains (U.S. Patent 4,014,321).

In European patent specification 0 074 428 a Ver drive and a device for quantitative determination of glucose described by laser light scattering. Here it is assumed that the glucose molecules have a scatter light beam transmitted through the solution and that the glucose concentration can be derived from this.  

According to this theory, the previously known The measurement procedure is based on the fact that the Infor tion about the glucose concentration from the solid angle distribution from a test cuvette or a examined body part emerging transmitted Light is available. In particular, the intensity of the transmitted light in an angular range, in which the change depending on the glucose concentration tration is as large as possible, measured and in relation to the one on the central beam, which is the sample in a straight line Direction penetrates, measured intensity set.

A spatially resolving scattered light measurement and an in-vivo Analysis in which the irradiation location and the detec location on the same side of the biological matrix are not described in the reference. Rather, only one is used for in vivo analysis Transmission measurement with laser light on the earlobe emp foal. The special advantages of laser light, namely Coherence and polarization are without Be in the invention interpretation because these properties of the primary light without lost due to multiple scattering.

According to the theoretical basis of EP-B-0 074 428 is assumed in this reference gene that the scatter with increasing glucose concentration tion increases, d. H. the intensity of the out of the direction of the primary beam scattered in transmission ge measured light should increase with increasing glucose concentrations tration get bigger. This would correspond to one in reflection Increase in at a detection site in the sense of the present intensity measured with increasing invention Glucose concentration. Within the scope of the present inven However, it was found that the diffuse reflect with light in the vicinity of the irradiation site  increasing glucose concentration decreases. This is true the explanation given above. The one with the Increase in glucose concentration related change the refractive index leads to a change in light scatter, and here to increase the depth of penetration in the biological matrix and to reduce the Intensity in the vicinity of the irradiation site.

In the device described in U.S. Patent 5,028,787 device for in vivo analysis of glucose is the distance of the Irradiation site and the detection site does. Irradiation and detection means each closely above the body part to be examined (especially one running under the skin surface Vein) at a defined distance l. The Ana lysis is based on the optical absorption by the glu cose. The length l is needed to measure from the Intensity I be the value log I / I of the optical density to be able to vote. There are detection measurements for several ren different wavelengths provided. The Ab stood between the irradiation site and the detection site and thus the optical path remains unchanged.

U.S. Patent 5,057,695 discloses a method and an Device described, with the "inner information" ei ner substance to be determined. All examples relate to the determination of the oxygenation state of the blood, so the relation of Hb and HbO₂. Even though it is said that in this analysis the light scatter is used, the calculation of the con centers on the determination of the molecular absorpti on coefficients of Hb and HbO₂. The light scatter bil det here only the transport mechanism the light radiated into the skin by two under different irradiation sites to a detection site  or from one irradiation site to two different ones Detection sites is transported. Accordingly It was important that the two irradiation sites or the two detection sites were as close as possible so that the "inner information" of the substance only in the immediate vicinity of the irradiation points or the detection points deviate from each other. The meas distance between the irradiation site and the detection location is at least 3 cm and preferably at least 4 cm. A measurement of glucose according to the present invention, at such large ab would not be possible. The reference also contains no reference to the analysis of glucose.

Also from WO 91/17 697 and EP-A-0 286 142 Devices or methods for determining oxygenia condition of the blood in human tissue a measurement of light reflected from the tissue knows, the apparatus described there a spatially resolved detection of the tissue emerging Enable light. The evaluation is also based on the sem case on absorption by that for oxygenia essential components of the blood. A Indicates ways to analyze glucose not to be found in these references either.

Order in the evaluation step from the intensity measurements the glucose concentration of the detection measurements is an evaluation algorithm and a calibration conducive. The invention differs in this respect not significantly from known analytical methods that also - as explained above - a calibration is required to measure the measured variable (for example, the color envelope for colorimetric tests) of the respective con assign center.  

In the simplest case, the algorithm contains the before lying invention a simple predetermined math matic function to derive from the intensity measurements I Detection measurements to determine an intermediate size that can be referred to as measurement variable R. Proven well in practice has a simple quotient formation between the In intensity measurements of the first and second detection measurements solution. By calibration with at least two, preferably but several standard samples of known glucose concentrations tion can then be measured variable R in a known manner link the concentration C of glucose.

In recent times, analytical technology has become increasingly popular mathematically more sophisticated methods used to make the Correlation between the measured values and the ge sought concentration (and thus the accuracy of analysis) to improve. This includes exponential or log arithmetic calculations and iterative procedures for optimal description of the assignment. For improvement the accuracy of the analysis can also be advantageous be influencing factors, in addition to the glucose concentration affect the measured intensity (such as in particular the temperature at the measuring location and the pulse) with the help of Cor to compensate for the relations procedure. To capture a Many influencing factors can be multilinear and not linear mathematical algorithms when evaluating Analysis measurements are used. This is also the case with the present invention possible and can be advantageous especially when a variety of detection measurements with different pairings of places of passage is carried out and the analysis is based. In the This can also be the case with the use of systems capable of learning (neural networks) may be advantageous.

The invention is described below with reference to the figures schematically illustrated embodiments he closer purifies; it shows

Fig. 1 is a perspective schematic representation of a first embodiment of the invention;

Fig. 2 is a perspective schematic diagram of a second embodiment of the invention;

Fig. 3 is a perspective schematic diagram of a third embodiment of the invention;

Fig. 4 is a perspective schematic diagram of a fourth embodiment of the invention;

Fig. 5 is a schematic diagram of the Einstrahlungsfel and a detection field in a plan view in a fifth embodiment of the invention;

Fig. 6 is a sectional view of a practical embodiment of a measuring head suitable for the invention;

FIG. 7 shows a view of the measuring head according to FIG. 6 from the side which is contacted with the biological matrix;

FIG. 8 shows an enlarged detail from FIG. 7;

Fig. 9 is a graphical comparison of the manure with the OF INVENTION and obtained using a reference method analysis results;

FIG. 10 is a side gate-sectional view of a measuring device for analysis on a finger;

Fig. 11 is a plan sectional view of the embodiment of Fig. 10;

Figure 12 is a plan view of the measuring apparatus in one embodiment according to Figures 10 and 11..;

Fig. 13 is a block diagram of an electronic circuit suitable for the invention.

In Figs. 1 to 4, an optically heterogeneous biolo gical matrix 10 is symbolically represented as a cube. It is limited by an upper interface 11 a and a lower interface 11 b. Specifically, the biological matrix can be blood, for example, in which case the interfaces run along the inner walls of an optically transparent vessel (cuvette) in which the blood is for analytical in-vitro analysis. If the biological matrix is a tissue, the interface is formed by the surface of the tissue.

Figs. 1 to 5 illustrate different Vari distinctive possible arrangements of one or more radiation-A or 12 or one or more detection locations 14 on a biological matrix 10 in a spatially resolved measurement of scattered light according to the invention. The irradiation locations 12 are each designed as narrow, elongated radiation fields 12 a- 12 f and the detection locations as elongated, narrow detection fields 14 a- 14 i. Insofar as it is not a question of the special features of the elongated shape, similar considerations also apply in the event that at least the one radiation site is point-shaped or circular.

In the embodiment shown in Fig. 1, the primary light 15 is irradiated by an irradiation field 12 a in the Ma trix 10 and the secondary light 17 is detected, which extends from two at different measuring distances D1 and D2 to the irradiation field 12 a detection fields 14 a and 14 b exits.

Also in the embodiment shown in FIG. 2 embodiment, the primary light passes 15 through a radiation field 12 b in the biological matrix 10 and the secondary light 17 by two detection fields 14 c and 14 d out of this, wherein the detection fields in different lateral measurement distances D1 and D2 are arranged from the irradiation field 12 b. The detection fields 14 c and 14 d are in this embodiment, however, on the interface 11 b, which is opposite to the interface 11 a through which the primary light 15 is radiated. In such an embodiment, the entry field and exit field are preferably arranged such that the surface of the exit field is not crossed by at least two pairs of measuring fields, the line of the radiation field perpendicular to the surface does not intersect. In other words, the detection field should not be arranged exactly opposite the radiation field, but should always be laterally offset from it.

One can speak of a measurement “in reflection” in the arrangement according to FIG. 1 and a measurement “in transmission” in FIG. 2, these terms being understood in the sense discussed above.

If the biological matrix is a tissue, in particular skin tissue, only an interface delimiting the matrix (namely the surface of the skin) is accessible in an in vivo analysis as a rule. This applies in particular to the parts preferred in the context of the invention, namely the fingertip, the upper abdominal wall, the nail bed, the sclera or the inner upper arm of the man. In these cases, only the - in the context of the present invention preferred anyway - measurement in the reflection method is possible, in which the irradiation of the primary light and the detection of the secondary light takes place at the same interface of the matrix. In exception cases, for example in the earlobe, lip or tongue, but are also available for the in vivo analysis of skin tissue two opposite boundary surfaces 11 a, 11 b is available.

In the embodiment shown in FIG. 3, the primary light is radiated into the biological matrix 10 through two irradiation fields 12 c, 12 d and the secondary light 17 emerging from the detection field 14 e is detected. The irradiation fields 12 d and 12 c are arranged at different measuring distances D1 and D2 from the detection field 14 e, so that in this embodiment there is also the possibility of the secondary light emerging from the detection field 14 e depending on the measuring distance from the respective one To measure the radiation field 12 c or 12 d in order to derive a measurement variable from the two measured values which is a measure of the concentration of the analyte in the biological matrix.

In this embodiment, the secondary light components that result from the primary light of the two different radiation fields must of course be separated from one another. This can expediently take place by irradiation separated in time, but the irradiation must take place at a sufficiently narrow time interval in the sense of the definition given above. Alternatively, it is also possible to use differently (for example with two different frequencies) modulated light for the irradiation into the two radiation fields 12 c and 12 d and the resulting secondary light components by means of a corresponding modulation-dependent (frequency-dependent) detection, for example with the help of a lock-in amplifier.

In all of the embodiments of FIGS. 1 to 3, the maximum measuring distance D2 between an irradiation location and a detection location of a spatially resolved scattered light measurement is 25 mm. The shorter distance D1 should be at least 0.5 mm, preferably at least 1 mm. In other words, in one embodiment according to FIG. 1 with a fixed irradiation location 12 and different detection locations 14, the detection locations should be in one (shown in dashed lines in the figure) ) Detection area 16 , which includes the part of the interface 11 a, which has a distance of at least 0.2 mm, preferably at least 0.5 mm, particularly preferably at least 1 mm and at most 25 mm from the center of the radiation location 12 . In an embodiment according to FIG. 3 with a fixed detection location 14 and different irradiation locations 12 , the corresponding values apply to the irradiation region 18 shown in broken lines there.

Fig. 4 shows an embodiment in which on the interface 11 a within a detection area 22 a plurality of different detection fields 14 f are adjustable, which run at different distances from an irradiation field 12 e. In the illustrated case, this is achieved in that the detection area 22 is imaged by an optical imaging system symbolized as a lens 23 in an image plane 24 in which there is a two-dimensional arrangement 26 photosensitive elements, which are preferably CCDs 25 (charge coupled device) are realized.

Due to the optical imaging, a certain detection field corresponds to a certain partial area of the CCD matrix 25 . For example, the field 14 f is mapped to the row 25 f and the field 14 g to the row 25 g of the CCD matrix 25 . A specific detection field can be set in a simple manner by the fact that the intensity measurement signals are processed further by those light-sensitive elements to derive the concentration to which the desired detection field is mapped.

On the basis of this embodiment, it is clear that the terms “radiation field” and “detection field” or “radiation location” and “detection location” are to be understood geometrically. It is not necessary for any components of the analysis device to touch the interface of the biological matrix, for example the surface of the skin, and to be in contact with the radiation site or the detection site. All that is required is that the irradiation location and the detection location are defined for each measuring distance, that is, the primary light is irradiated at a certain and limited irradiation location and the secondary light is detected locally in such a way that it is known from which specific delimited partial area of the interface (detection location ) the secondary light has escaped, the intensity of which is detected in each case. Such a measurement process must take place with at least two different light paths between a radiation location and the detection location in order to derive the measurement variable characteristic of the analysis from the intensity measurement values measured therefrom. If - as in the embodiment according to FIG. 4 - a plurality of different distances between the irradiation site and the detection site can be set, the course of the measured intensity I is expediently determined as a function of the measuring distance D between the respective detection site and the irradiation site. If a large number of closely adjacent detection locations can be set, the result is a practically continuous curve profile I (D) which represents the profile of the detected secondary light as a function of the distance between the respective irradiation location and the respective detection location. In this case, a suitable regression algorithm known for such purposes can be used to derive the measured variable characteristic for the analysis (for example PLS).

The embodiment with a detection area in which a large number of different partial areas can be set as detection fields can of course also be implemented without the optical imaging system 23 shown in FIG. 4. In particular, it is possible to position a two-dimensional arrangement of light-sensitive elements directly above the interface 11 a, with care being taken with the aid of suitable means, such as, for example, screens, light guides or the like, that each light-sensitive element is made up of a specific, delimited part rich the interface 11 a emerging secondary light he summarizes.

It is important for the invention that the dependence of the intensity of the secondary light I on the distance D between the irradiation site and the detection site is detected with good spatial resolution. Therefore, both the radiation site 12 and the detection site 14 should have a small dimension, preferably less than 2 mm, in the direction of the straight line connecting the two fields. It is particularly preferred, in particular in the case of the detection location 14 , the illustrated shape of an elongated, narrow field. This allows a good spatial resolution to be combined with a relatively high signal intensity. The length of a detection field should be at least three times, preferably at least ten times and particularly preferably at least thirty times as large as its width. The average width of the radiation field is preferably less than 2 mm, particularly preferably less than 1 mm. The same preferred dimensions also apply to the detection field. The different detection fields and / or irradiation fields, by means of which the different measuring distances are realized, are preferably spatially separated (not overlapping).

An embodiment in which a large number of different detection locations can be detected by means of a two-dimensional arrangement of photosensitive elements (as in FIG. 4) additionally enables improved reproducibility of an always identical measuring position on a skin surface. For this purpose, a marking (for example by means of a tattoo that is invisible in normal light but contrasting in NIR light) can be applied to the skin at the measuring position provided for a particular patient. This is recognized and localized by the two-dimensional arrangement of light-sensitive elements. By this location measurement, it is possible either to bring the measuring head of the device according to the Invention into a certain always constant position in relation to the marking or to select the detection fields within the two-dimensional arrangement of photosensitive elements in always the same spatial assignment to the marking.

Fig. 5 illustrates that the narrow, elongated shape of the fields does not necessarily have to be straight (as in Figs. 1 to 4). A radiation field 12 f in the form of a section of a circular ring is shown in a view of an interface. Two detection fields 14 h and 14 i also run in the form of circular sections cut at different distances from the radiation field 12 f. The circular rings are concentric, so that the detection fields 14 h and 14 i were at a uniform distance from the radiation field 12 f.

A good spatial resolution is achieved when the light is on a narrowly limited (punctiform) jet Radiation site is irradiated and the detection site Circle or segment of a circle around this irradiation site det. Basically, it can also be reversed with a circle shaped radiation site and one in the center of this Circle arranged point-shaped detection site tet, where the signal intensity is lower.

If - as shown in FIGS . 1 to 4 - radiation fields and detection fields run straight and parallel to one another, the spatial resolution is lower because, of course, light components are measured at every point of an elongated detection location, not only from the directly opposite section of the radiation field , but also from sections of the radiation field offset in the longitudinal direction. In the practical testing of the invention, however, it was found that a satisfactory location resolution can still be achieved with a relatively high signal intensity with an arrangement in which both the irradiation site and the detection site has an elongated shape. The execution form according to FIG. 5 in that illustrates an intermediate solution, as here, the spatial resolution is better than in the straight shape of the fields shown in FIGS. 1 to 4 because of the curved concentric shape.

Other curved shapes are also possible, although the general condition that the passage fields (measured from center to center) run at a uniform distance D1, D2 should be observed. Insofar as the radiation site and the detection site are on the same interface of the biological matrix, the radiation site and the detection site should always be separated by a strip 47 ( FIG. 5) of essentially uniform width. The dimension of the detection field in the direction of the shortest connection to the radiation field (ie in the direction of the distance arrows D1, D2) should be less than 2 mm, preferably less than 1 mm.

FIGS. 6 to 8 show a practical execution of a form suitable for the invention the measuring head 30 which is particularly suitable for in vivo determination of glucose in men Schlichem tissue.

The measuring head 30 has an approximately circular disk-shaped skin contact part 31 , which is attached to a measuring head housing 32 . The skin contact part 31 is placed in use on the surface of the skin 33 and pressed lightly. At its center is a square light transmission area 34 , which is shown enlarged in FIG. 8. It contains five rows 35 to 39 of optical fibers 29 , which, in the example shown, each consist of thirty-two fibers, each with a diameter of 0.25 mm. The optical fibers 29 are each arranged in the light transmission region 34 such that their end faces lie flush in a common flat contact surface 42 and are in direct contact with the skin when the skin contact part 31 is placed on the skin 33 .

The series 35 of optical fibers defines a radiation site. For this purpose, the optical fibers 29 of this series are connected by a cable 40 to a central unit, not shown, in which there is a preferably monochromatic light source, for example a laser or a laser diode, the light of which is radiated into the optical fibers 29 . The optical fibers 29 form together with the light source (not shown) (for example a light-emitting diode, the light of which is coupled in the usual way into the optical fibers) light irradiation means 27 for selectively illuminating a defined irradiation site on a skin surface.

A part of the optical fibers of the row 35 is preferably used to control the constancy of the light source. In a concrete experiment, sixteen of the thirty-two fibers were used to irradiate the light and the other sixteen fibers to control the light intensity, the latter being combined separately from the former and fed to a photosensitive element.

As a measuring receiver, for example, photodiodes can be used, which are arranged in the measuring head 30 . Since it is useful for each row 36 to 39 of optical fibers 29 , each defining a possible detection location, to see a common measuring receiver. The optical fibers of these rows are thus summarized to a respective measuring receiver at which the light emerging from these optical fibers is detected. The rows 36 to 39 of the optical fibers 29 form together with the measuring receiver, not shown, each detection means 28 for targeted measurement of the secondary light emerging at a defined detection location.

The end faces of the optical fibers of the rows 35 to 39 each terminate flush with the skin contact surface 42, which delimits the light emission region 34 downward, or protrude slightly therefrom. This prevents ver that light along the surface of the skin can get directly from the irradiation location defined by the row 35 to one of the detection locations defined by the rows 36 to 39 . Of course, within the measuring head 30, the glass fibers are optically carefully separated from one another under different rows, so that no transmission of primary light to the detection means can take place.

The measuring head 30 is intended in particular for monitoring the blood glucose level of diabetics. For this purpose, it is attached to a suitable location, in particular on the upper abdominal wall on the skin. This can be done for example with the help of an adhesive tape or by vacuum suction. The contact surface 42 should be pressed with sufficiently firm and even pressure.

In order to keep out extraneous light, the skin contact part 31 has a ring 31 a, the diameter of which is considerably larger than that of the light transmission region 34 . It consists of an opaque material and closes with its edge 31 b on the skin and also keeps out extraneous light. Alternatively or additionally, the primary light can be modulated with a certain frequency and can be selectively detected in a narrow-band manner depending on the frequency (for example with the aid of a lock-in amplifier) in order to reduce the effects of stray light.

The light emission region 34 is surrounded by an annular heating surface 41 , in which a surface resistance heater is arranged. This can be regulated to a predetermined temperature, for example 37 °, with the aid of an NTC resistor and a PD controller.

FIG. 9 shows analysis results which were achieved on the one hand with a reference method and on the other hand with a device according to the invention (embodiment according to FIGS. 6 to 8). The concentration C is plotted in mmol / l over the time t in minutes. The solid line 45 marks the results of an enzymatic analysis used as a reference method, while the rectangular markings are 46 measuring points with the device according to the invention.

In the example according to the invention, the following were Measurement conditions met.

It has a measuring head is shown in FIGS. 6 to 8 is wherein the light from a light emitting diode with 1 mW Lei stungen and a wavelength of 805 nm through the light leitfaser series 35 into the skin of irradiated and detected by the rows 38 and 39 . The distance between rows 38 and 39 from row 35 (and consequently the distance of the detection fields from the irradiation field) was 3 mm and 5 mm, respectively.

To derive a characteristic variable R for the concentration, the quotient between the intensity I1 of the row 39 and the intensity I2 of the light measured on the row 38 was formed. This measured variable R = I1 / I2 was linearly calibrated according to the formula

C = a _* R + b.

The result shown in Fig. 9 shows an excellent agreement between the conventional and he measured values over a period of five and a half hours.

FIGS. 10 and 11 show a Meßhalterung 50 for the determina tion of the glucose concentration in a fingers 51. The finger 51 is inserted into a precisely fitting channel 52 which is formed in a mounting block 53 . The mounting block 53 is made of aluminum or another good heat-conducting material, which is set with a heating and Thermostatisierungseinrich device, not shown, to a defined temperature, which is preferably slightly above the normal body temperature (above 37 ° C).

The wall element 54 which laterally delimits the channel 52 can be displaced such that the width of the channel 52 can be adapted to the finger 51 of the respective patient. To fix the finger 51 from above Fixie tion elements 55 are provided, which are slidably held in the direction of the fin ger 51 and pressed with a spring not shown Darge against the finger 51 .

The mounting block 53, the wall elements 54 and the Fi xierungselemente 55 together form a channel 52 defining in the insertion stop 56 total fixing means by which the fingers 51 in an AS POSSIBLE accurately reproducible position with respect to the designated overall by 58 measuring means is positioned .

In the measuring device 58 , light irradiation means 27 are formed by a light-emitting diode (not shown) and by a light guide channel 59 , through which primary light is directed to a circular irradiation site of approximately 1 mm in diameter on the underside of the tip of the finger 51 . In a detection area 16, three detection sites 14 are provided, which m the irradiation site 12 concentrically surrounded than semicircular detection fields 14 k- fourteenth The detection means 28 consist, as can be seen more clearly in FIG. 12, again of a row of light guide fibers 29 arranged close to one another, the end faces of which surround the light guide channel 59 in the skin contact area 42 in a semicircular manner and a photo receiver for the light from each of the detection locations 14 k, 14 l, 14 m. The light irradiation means 27 are carefully shielded from the detection means 28 by a partition 62 .

An infrared temperature sensor 60 is directed to a temperature measurement location 61 , which should be as close as possible to the detection region 16 .

In the practical testing of the invention, it has proven to be important that the contact pressure between the respective body part and the skin contact surface of the measuring device is sufficiently high and reproducible. In the embodiment shown in FIGS. 10 and 11, this is done with the aid of a pressure stamp 63 , which presses from above onto the foremost member of the finger. A pressure force of approximately 300 p (pond) has proven to be suitable.

Fig. 13 shows an example of the block diagram of an electronic circuit 65, which is suitable as evaluation of an inventive measuring device. A voltage-current converter 67 is driven by an oscillator 66 and feeds the light-emitting diode 68 , which serves as a light source. The temperature of the light-emitting diode 68 can optionally be monitored by an NTC 69 in order to improve the constancy of the intensity of the emitted light.

The output signals of the measuring receivers (photodiodes) 70 a- 70 c are each via a preamplifier circuit 71 a- 71 c to lock-in amplifiers 72 a- 72 c, to which the signal of the oscillator 66 is also fed as a reference. The output signals of the lock-in amplifier 72 a- 72 c are digitized in an A / D converter unit 73 and fed to a microcomputer central unit 74 . The microcomputer central processing unit also receives the signals from the NTC 69 (amplified by a preamplifier 69 a) and a temperature sensor 75 (amplified by a preamplifier 75 a) for measuring the temperature in the detection range, which preferably (like the IR Sensor 60 of the embodiment according to FIG. 10) operates contactlessly.

Claims (40)

1. A method for determining the concentration of glucose in a biological matrix ( 10 ), comprising
at least two detection measurements, in which each weils light is irradiated by the biological matrix (10) boundary surface (11 a) as the primary light (15) into the biological matrix (10), the light in the biological matrix (10) along an optical path propagates and a light intensity emerging from the biological matrix ( 10 ) through an interface ( 11 a, 11 b) delimiting it as secondary light ( 17 ) is measured, and
an evaluation step in which the glucose concentration is derived from the intensity measurement values of the detection measurements by means of an evaluation algorithm and a calibration,
in which
a first detection measurement is a spatially resolving scattered light measurement, in which the primary light ( 15 ) is irradiated into the biological matrix at a defined irradiation location ( 12 ), the intensity of the secondary light ( 17 ) emerging from the biological matrix at a defined detection location ( 14 ) is measured and the detection site ( 14 ) is arranged relative to the radiation site ( 12 ) so that at scattering centers ( 19 ) of the biological matrix ( 10 ) many times scattered light is detected, the intensity of which is characteristic of the concentration of glucose, and
the light path in a second detection measurement is different from that of the first detection measurement. 2. The method according to claim 1, in which the second detection measurement is a spatially resolving scattered light measurement, in which the primary light ( 15 ) is irradiated into a defined irradiation site in the biological matrix, the intensity of the at a defined detection site ( 14 ) from the biological matrix emerging secondary light ( 17 ) is measured and the detection location ( 14 ) relative to the irradiation location ( 12 ) is arranged so that scattered light is detected at scattering centers ( 19 ) of the biological matrix ( 10 ), the intensity of which for the con concentration of glucose is characteristic. 3. The method according to claim 1 or 2, wherein the biological matrix ( 10 ) is a biological liquid, in particular blood. 4. The method of claim 1 or 2, wherein the biological matrix ( 10 ) is a biological tissue. 5. The method of claim 4, wherein the biolo Tissue tissue Skin tissue, especially on the fingers berry, the upper abdominal wall, the nail bed, the lip, the tongue, the sclera or the inner upper arm of the Is people. 6. The method according to any one of the preceding claims, wherein the primary light ( 15 ) is monochromatic with a half width of less than 100 nm, before given less than 20 nm, particularly preferably less than 5 nm. 7. The method according to any one of the preceding claims, wherein in the at least one spatially resolving scattered light measurement, the distance (D) between the center of the irradiation site and the center of the detection site is at least 10 times the free path length of the photons in the biological matrix ( 10 ) is. 8. The method according to any one of the preceding claims, in which at least one spatially resolving Scattered light measurement the distance between the center of the Irradiation location and the center of the detection location is at most 25 mm, preferably at most 15 mm and particularly preferably at most 10 mm. 9. The method according to any one of the preceding claims, wherein the detection location ( 14 ) is designed as a narrow, elongated, straight or curved detection field ( 14 a - 14 m). 10. The method according to claim 9, wherein the dimension of the detection field ( 14 a- 14 m) in the spatial direction defined by the shortest connection to the radiation site ( 12 ) is less than 2 mm on average. 11. The method according to any one of the preceding claims, wherein the irradiation site ( 12 ) is designed as a narrow, long irradiation field ( 12 a- 12 f). 12. The method according to claim 11, wherein the dimension of the radiation field ( 12 a- 12 f) in the spatial direction defined by the shortest connection to the detection field ( 12 ) is less than 2 mm on average. 13. The method according to any one of the preceding claims, wherein the irradiation site ( 12 ) and the Detek tion site ( 14 ) on opposite interfaces ( 11 a, 11 b) of the biological matrix ( 10 ) are arranged. 14. The method according to claim 13, wherein the detection location ( 14 ) is not crossed by any straight line crossing the surface of the irradiation location ( 12 ). 15. The method according to any one of the preceding claims, wherein the irradiation site ( 12 ) and the Detek tion site ( 14 ) at the same interface ( 11 a) of the biological matrix are arranged to measure diffusely reflected radiation from the Ma trix ( 10 ) . 16. The method of claim 15, wherein the detecti onsort lies in a detection area, which is the part of the interface, which is a distance of at least 0.2 mm, preferably at least 0.5 mm, be particularly preferably at least 1 mm and at most 25 mm, preferably at most 15 mm, particularly preferred at most 10 mm from the center of the irradiation site has, and the intensity of the secondary light in minde decreases at least part of the detection range, when the glucose concentration increases. 17. The method according to any one of claims 15 or 16, wherein the irradiation site ( 12 ) and the detection site ( 14 ) are separated by a strip ( 47 ) of substantially uniform width. 18. The method according to any one of claims 2 to 17, in which chem the irradiation site ( 12 ) and the detection site ( 14 ) in the first and the second spatially resolving scattered light measurement have different measuring distances (D1, D2) from each other. 19. The method of claim 18, wherein the sub the measuring distances (D1, D2) at the first and second spatially resolving scattered light measurement at least 30%, preferably at least 50%, particularly preferred is at least 70% of the shorter measuring distance. 20. The method according to any one of claims 2 to 19, in which chem the detection location ( 14 ) matches in the first and the second spatially resolving scattered light measurement. 21. The method according to any one of claims 2 to 20, in which chem the irradiation location ( 12 ) in the first and the second spatially resolving scattered light measurement matches. 22. The method according to any one of the preceding claims, wherein the detection site (14) Part of a size ren detection area (22) on which a plurality onsorte of different sub-areas as Detekti (14) can be adjusted to the Inten intensity of at a plurality of detection sites ( 14 ) emerging secondary light ( 17 ) as a function of the distance from an irradiation site ( 12 ) to measure. 23. The method according to claim 22, in which the light intensity emerging in the detection area ( 22 ) from the biological matrix ( 10 ) is detected by a two-dimensional arrangement ( 26 ) of photosensitive elements ( 25 ) and the signals of the photosensitive elements of an image processing device be fed. 24. The method according to any one of the preceding claims, at which the wavelength of the primary light between Is 400 nm and 2500 nm. 25. The method of claim 24, wherein the waves length of the primary light between 780 and 825 nm is preferably between 800 and 805 nm. 26. The method of claim 24, wherein the waves length of the primary light between 1150 and 1350 nm, preferably between 1200 and 1300 nm. 27. The method according to any one of the preceding claims, in which primary light having a plurality of different wavelengths is radiated into the biological matrix ( 10 ) and the wavelength-dependent intensity of the secondary light ( 17 ) measured at at least one detection location ( 14 ) is detected and is derived device is used. 28. The method according to any one of the preceding claims, wherein the temperature at the detection location ( 14 ) is preferably measured without contact and is taken into account in the evaluation algorithm. 29. The method according to any one of the preceding claims, wherein the temperature at the detection site ( 14 ) is kept stable. 30. Device for determining the concentration of glucose in a biological matrix, in particular for carrying out the method according to one of the preceding claims, with
a light transmission region ( 34 ) provided for application to an interface of the biological matrix,
Irradiation means ( 27 ) for irradiating light into the biological matrix ( 10 ) through an interface ( 11 a, 11 b) bordering it,
Detection means ( 28 ) for measuring the intensity of light emerging from the biological matrix ( 10 ) through an interface ( 11 a, 11 b) delimiting it and
Evaluation means for converting the measured intensity into a signal corresponding to the glucose concentration,
in which
the irradiation means ( 27 ) are designed to specifically illuminate a defined irradiation location ( 12 ) and the detection means ( 28 ) are designed to specifically measure the secondary light emerging from a defined detection location ( 14 ), the detection location ( 14 ) being relative to the irradiation location ( 12 ) is arranged so that scattered light is detected at scattering centers ( 19 ) of the biological matrix ( 10 ), the intensity of which is characteristic of the concentration of glucose. 31. The device according to claim 30, wherein at least two light irradiation means ( 27 ) are provided, which are designed for the targeted illumination of different, spatially non-overlapping irradiation locations. 32. Apparatus according to claim 30, in which at least two detection means ( 28 ) are provided, which are designed for targeted measurement of the secondary light emerging from the biological matrix at two different, spatially non-overlapping detection locations. 33. Device according to one of claims 30 to 32, wherein the irradiation means ( 27 ) include optical fibers ( 29 ). 34. Apparatus according to claim 33, wherein the light irradiation means ( 27 ) include a plurality of optical fibers ( 29 ) which are arranged in the light transmission area as a row ( 35 ) next to one another to form a narrow, elongated radiation field ( 12 a - 12 f) specifically illuminate the irradiation site ( 12 ). 35. Apparatus according to claim 33, wherein the light irradiation means ( 27 ) include a plurality of optical fibers ( 29 ) which are arranged closely adjacent in the light transmission region ( 34 ), a first part of the optical fibers ( 29 ) for feeding the Primary light serves for the biological matrix ( 10 ) and a second part of the optical fibers ( 29 ) is connected to a detector for checking the intensity of the primary light. 36. Device according to one of claims 30 to 35, wherein the detection means ( 28 ) include optical fibers ( 29 ). 37. Apparatus according to claim 36, wherein the detection means include a plurality of optical fibers, which are arranged next to one another in the light transmission region ( 34 ) as a row ( 36-39 ) in such a way that they consist of an elongated, narrow detection field ( 14 a - 14 m) trained detection location ( 14 ) leaking secondary light ( 17 ) capture target. 38. Device according to one of claims 30 to 37, wherein the optical fibers in the light transmission area ( 34 ) are arranged so that their end faces are flush in a common skin contact surface ( 42 ) so that they are in direct contact with the interface ( 11 a) of the biological matrix ( 10 ) stand when the device with the light transmission region ( 34 ) is placed on the interface ( 11 a). 39. Device according to one of claims 30 to 38, wherein the detection means include a two-dimensional arrangement ( 26 ) of photosensitive elements ( 25 ), in particular a CCD array. 40. Device according to one of claims 30 to 39, which light shielding means are provided, which the Transmission of primary light from the light beam means for the detection means on another prevent pathways than through the biological matrix.