Method, computer program product, radiometer and system for determining glucose concentration in tissue

Abstract

The method for non-invasive determination of blood glucose concentration in a patient's tissue based on a wireless noise signal received using an antenna close to the patient's skin according to the present invention comprises measuring the wireless noise signal using a passive radiometer and in addition the method comprises the steps of: obtaining transform coefficients, measuring the temperature of the tissue surface, measuring the temperature of the active elements of the receiver chain of the radiometer, measuring the current consumed by the active elements of the receiver chain of the radiometer, measuring the power of the wireless noise signal originating from the tissue, and determining the blood glucose concentration based on the above values. The present invention also relates to a computer program, a radiometer and a device for determining glucose concentration.

Description

Technical Field

[0001] The present invention relates to a method for determining glucose concentration in tissues (particularly blood), a computer program product, a radiometer, and a system for determining glucose concentration in tissues. Background Technology

[0002] Determining blood glucose concentration (i.e., blood sugar) is important because it is necessary to monitor glucose levels that are relevant to the treatment and prevention of diabetes.

[0003] Blood tests can provide accurate results for diagnosing diabetes. However, this is associated with negative stimuli for patients (i.e., pain associated with invasive procedures), so work on alternative solutions is ongoing. This is especially true for mobile devices. Various technologies are being used, including iontophoresis, ultrasound, respiratory biomarker detection, temperature measurement, examining tissues with electromagnetic waves and light, and examining radiation reflected from tissues.

[0004] In the field of measurement using microwave radiometer technology, there are many radiometer system schemes used to measure the temperature inside tissues for cancer diagnosis, core temperature measurement, vesicoureteral reflux diagnosis, brain temperature measurement, etc. Passive radiometers have no transmitter and are devices that measure the radiant flux (power) of electromagnetic radiation, especially noise. Therefore, they are suitable for indirect temperature measurement, as described in the MDPI and ACS Style Guide, Park W. and Jeong J.; "Total Power Radiometer for Medical Sensor Applications Using Matched and Mismatched Noise Sources"; Sensors 2017, Vol. 17, p. 2105, https: / / doi.org / 10.3390 / s17092105. A total power radiometer is a simple construction with cascaded amplifiers in the receiver chain and detector for directly measuring the power of the input (noise) signal. The power is usually converted to temperature units, i.e., so-called luminance temperature. Total power radiometers can be used in more complex receiver configurations, including switches and devices for reference measurements. Advanced constructions, including passive total power radiometers, include the Dicke radiometer and the correlated radiometer K. These constructions are based on using a reference from a normalized reference noise source. The Dicke radiometer uses a chain of switched receivers to measure the input signal and the reference source sequentially. The correlated radiometer contains two identical receiver chains, each based on a full power radiometer. Other constructions of passive radiometers based on one or more passive radiometers also exist.

[0005] European patent application EP1949084 discloses a device for minimally invasive measurement of the concentration of components contained in biological tissue structures. This device includes a microwave energy source generating a microwave frequency range, a first antenna connected to the microwave energy source and adapted to transmit at least a portion of the microwave energy to the tissue structure, a second antenna adapted to receive at least a portion of the microwave energy transmitted through the tissue structure, a signal processor adapted to determine the resonant frequency of the received microwave energy, and a data processor adapted to provide an output of the concentration of components in the biological tissue structure based on the determined resonant frequency. US2016051171 discloses a device for probing human skin using tight coupling between a millimeter-wave transmitter and receiver. It uses a method of evaluating the amplitude and / or phase changes of the emitted millimeter waves to estimate blood glucose concentration. DE102006055691 discloses a device having a diagnostic measurement unit for generating measurement signals and an evaluation unit for determining physiological parameters by processing the measurement signals. The measurement unit is integrated into the keyboard of a computer (e.g., a laptop computer). The measurement unit is an optical measurement unit used to generate blood oxygenation and / or plethysmography measurement signals. An evaluation unit is provided to determine local metabolic parameters, such as local oxygen consumption, from the signals from the optical measurement unit. Document WO2019147582 specifically discusses systems and methods for compensating for the effects of temperature on sensors (e.g., analyte sensors). An example method may include: receiving a temperature signal indicating a temperature parameter of an external component, receiving a glucose signal indicating an in vivo glucose concentration level, and determining a compensated glucose concentration level based on the glucose signal, the temperature signal, and a delay parameter, thereby determining a temperature-compensated glucose concentration level.

[0006] CN110074790 discloses a method for non-invasively determining blood glucose concentration based on the blood layer in the earlobe using time-domain processed microwave signals. The method includes the following steps: creating an earlobe model; preparing test solutions with different glucose concentrations to simulate blood glucose concentrations; placing two antennas on both sides of the earlobe model, wherein the transmitting antenna transmits a high-frequency sinusoidal signal, and the receiving antenna receives a sinusoidal signal passing through the simulated earlobe tissue. Calibration coefficients can be determined by using glucose solutions of different concentrations during measurement and signal reception. The received signal (i.e., the received signal) is analyzed in the time domain, wherein this analysis includes filtering noise in the signal using a wavelet transform algorithm, analyzing the trend of the filtered received signal with changes in glucose concentration, and obtaining the functional relationship between the amplitude of the energy density spectrum of the noise-filtered signal and the glucose concentration value.

[0007] Protocols based on exposing patients to radiation (infrared, light, or radio waves) or ultrasound have drawbacks, namely that they are not always harmless to patients. This is especially true for children under 2 years old and pregnant women. Occasional exposure may not have a significant impact on patients, but continuous exposure (such as when using wearable devices to measure blood glucose levels) may not be insignificant, and long-term studies are needed to validate the consequences of such exposure.

[0008] European patent application EP1224905 discloses the use of a total power radiometer in temperature measurement, wherein the radiometer operates in a 400 MHz or 100 MHz band with a center frequency of 1.5 GHz or 3.5 GHz, and analyzes the noise radiation generated by the tissue to determine the temperature.

[0009] In her 2006 MSc paper at Baylor University, "A Microwave Radiometer System for Use in Biomedical Applications," Laura Ballew proposed using a microwave radiometer to determine blood glucose levels. This approach is highly complex and requires a precise noise source with a stable temperature to achieve the desired result for the Dicke-configured radiometer.

[0010] Various radiometer designs are commonly used: total power radiometer (TPR), Dicke radiometer, and correlation radiometer.

[0011] The disadvantage of TPR is that its gain is sensitive to temperature changes. Its advantages include simple structure—basically a cascaded amplifier with a detector at the end. Its advantage is simplicity, but its disadvantage is susceptibility to changes in noise characteristics caused by gain variations and component temperature variations. This is problematic because temperature variations depend not only on the environment but also on the heat released in the components of the receiver chain due to bias power dissipation.

[0012] Dicke radiometers require additional noise sources with precise, stable temperatures, as well as microwave components (circulator and switch types) to achieve gain control. In the Dicke construction, a single total power radiometer switches between two input signals: the measurement signal and reference noise. This design reduces sensitivity to gain and temperature variations. An example of a Dicke radiometer can be found in the paper "A novel Dicke microwave radiometer without temperature control for reference matchload" by Yan Li, Liang Lang, Qingxia Li, Siyuan Liu, and Liangqi Gui, published in the proceedings of the IEEE International Conference on Microwave and Millimeter Wave Technology (ICMMT) held in Beijing, China in 2016, pp. 880-882, doi:10.1109 / ICMMT.2016.7762473. Another example can be found in the works of J. Lee, G.S. Botello, R. Streeter, K. Hall, and Z. Popovi. The co-authored paper, “A Hybrid Correlation-Dicke Radiometer for Internal Body Thermometry,” is included in the proceedings of the 52nd European Microwave Conference (EuMC) held in Milan, Italy in 2022, pp. 464-467, doi: 10.23919 / EuMC54642.2022.9924276.

[0013] Correlated radiometers require two total power radiometers and additional components in the form of microwave couplers, several detectors (2 to 8), and a reference noise source. This design ensures insensitivity to gain variations. An example of a correlated radiometer is disclosed in "Applications of the Pseudo-Correlation Microwave Radiometer" by Tanner, J. Bosch-Lluis, and P. Kangaslahti, presented at the IGARSS 2022 - IEEE International Symposium on Earth Sciences and Remote Sensing in Kuala Lumpur, Malaysia, pp. 7241-7244, doi:10.1109 / IGARSS46834.2022.9883145.

[0014] Problems to be solved The challenge is to find a passive and non-invasive method for determining glucose concentration in tissues based on measurements that involve a simple device that allows for miniaturization and is compatible with simple electronic circuitry—not only portable but also wearable. Summary of the Invention

[0015] The computer-implemented method according to the invention is used for non-invasively determining glucose concentration in patient tissue based on wireless noise signals (particularly microwave noise signals) received using an antenna close to the patient's skin. The difference lies in the use of a passive radiometer to receive the wireless noise signals, advantageously a total power passive radiometer. The passive radiometer does not require a transmitter or signal source but is adapted to measure low-power noise signals emitted by the object. Furthermore, the method includes the following steps: obtaining a transformation coefficient; measuring the tissue surface temperature; measuring the temperature of the active element of the radiometer receiving chain; measuring the current consumed by the active element of the radiometer receiving chain; measuring the power of the wireless noise signal originating from the tissue; and determining the glucose concentration in the tissue based on the transformation coefficient, the temperature value of the tissue surface, the temperature of the active element of the radiometer receiving chain, the consumed current, and the power of the wireless noise signal originating from the tissue. The total power radiometer is simple in design and easy to miniaturize. Determining glucose concentration based on noise power requires determining the transformation coefficient to establish the relationship between the noise power generated by the tissue and the effect of glucose concentration on antenna mismatch. Glucose concentration affects the impedance of the tissue and therefore the impedance matching of the antenna. The coefficient can be determined in a reference measurement. In benchmark measurements, the transformation coefficient of the receiver chain can be determined by measuring the temperature and current consumption of its components. This allows for simpler, miniaturized designs. This method is also applicable to improving the measurement accuracy of different types of radiometers.

[0016] Advantageously, the method is implemented in a computer, and in the step of obtaining the transformation coefficients, predefined transformation coefficients are loaded from computer memory or downloaded from an external server.

[0017] Advantageously, the transformation coefficient is determined based on a series of measurements performed on a set of tissues or phantoms with known glucose concentrations at different temperatures.

[0018] Advantageously, the transformation coefficients are determined in a multiple regression process, which involves minimizing the error in matching a glucose concentration baseline value to a value calculated from the transient characteristics of the radiometer, where the variables are: the temperature of the tissue surface, the temperature of the active elements of the radiometer receiver chain, the current consumed by the active elements of the radiometer receiver chain, and the power of the wireless noise signal. The simplest approach is to use a mean squared error criterion.

[0019] Advantageously, converting the measured value and transformation coefficient into a blood glucose concentration includes the following steps: determining the power of the noise received by the antenna based on the transformation coefficient, the power measured using the radiometer, the temperature of the active element of the receiver chain, and the current consumed by the active element of the radiometer's receiver chain. Next, using the previously determined power of the noise received by the antenna, the transformation coefficient, and the measured tissue surface temperature, determining the power of the noise originating from the tissue and reaching the antenna, as well as the reflection coefficient at the junction between the antenna and the tissue. Finally, using the determined reflection coefficient at the junction between the antenna and the tissue, and the determined power of the noise originating from the tissue and reaching the antenna, determining the glucose concentration.

[0020] Advantageously, the transform coefficients are the weight coefficients of the neural network that processes the dataset, which includes the measured temperature, the current consumed by the active elements of the radiometer receiver chain, and the power of the wireless noise signal originating from the tissue.

[0021] Advantageously, measurements of wireless noise signals are performed in a frequency band from 800 MHz to 24 GHz. Measurements within this frequency range are reliable and have proven to be repeatable.

[0022] Advantageously, measurements are performed in a frequency band with a bandwidth of 200 MHz or greater, and even more advantageously in a frequency band with a bandwidth of 500 MHz or greater. This allows for faster measurement execution and eliminates the influence of patient movement.

[0023] A computer program product adapted to receive measurement data according to the present invention includes instructions that cause the method according to the present invention to be executed.

[0024] The radiometer according to the invention includes an antenna and a wireless receiving chain with detectors. The antenna is adapted to be applied to a patient's skin and to receive wireless noise signals from subcutaneous tissue. The radiometer is a passive radiometer adapted to measure the power of the noise signals originating from the tissue. The radiometer is equipped with sensors for the temperature of the active elements of the receiving chain, a sensor for the patient's temperature placed on the antenna, and a sensor for the current consumed by the active elements of the radiometer's receiving chain.

[0025] Advantageously, the antenna's bandwidth is at least 20% wider than the receiver chain's bandwidth. For this reason, the device is resistant to drift in the skin's propagation parameters and related shifts in the antenna's operating bandwidth.

[0026] Advantageously, the radiometer's receiver chain includes a cascade of amplifiers separated by isolators.

[0027] Advantageously, the receiver chain comprises a cascade of amplifiers separated by attenuators, with a rated attenuation of less than 3 dB.

[0028] The system for determining glucose concentration based on wireless signals according to the present invention includes a processing system and a radiometer having an antenna adapted to be applied to a patient's skin. The difference lies in that the radiometer is a radiometer according to the present invention, and the processing system is connected to: a sensor for the temperature of the active element of the radiometer receiver chain, a sensor for the temperature of the tissue surface placed on the antenna, and a current measurement module for measuring the current consumed by the active element of the radiometer receiver chain. The processing system is adapted to perform the method according to the present invention. This system can be miniaturized and used as a wearable system while ensuring high accuracy. Attached Figure Description

[0029] The subject matter of the invention is described in the embodiments shown in the accompanying drawings, wherein... Figure 1 A block diagram of a system for determining glucose concentration according to the present invention is shown. Detailed Implementation

[0030] According to the present invention, a passive approach is used. No signal is transmitted to the tissue; instead, a total power radiometer measures the noise signal from the tissue.

[0031] A total power radiometer is a wireless receiver that includes an antenna and a wireless receiving chain with detectors, such as... Figure 1 The block diagram is shown. Antenna 2 is adapted to be applied to the patient's skin 1 and receives wireless noise signals from subcutaneous tissue.

[0032] This antenna is a broadband antenna with an operating bandwidth of approximately 1 GHz, which is wider than the operating bandwidth of the radiometer chain, equivalent to 300 MHz in this example. Therefore, the entire system can function even with antenna bandwidth drift caused by changes in electrodermal parameters, primarily due to changes in skin moisture caused by sweating or TEWL (transdermal water loss). In this embodiment, antenna 2 is fabricated using asymmetric stripe (so-called microstrip) technology, with the substrate size and dielectric constant chosen to receive radiation originating from skin 1. The advantage of microstripes is that the antenna structure itself shields against interfering signals not originating from the patient's skin. Other antenna designs that ensure signal reception from tissue can also be used by those skilled in the art.

[0033] Antenna 2 is directly connected to a radiometer chain comprising a cascade of the following components: four amplifiers 3, 5, 7, and 9 with a gain of approximately 20 dB; a bandpass filter 10 with a bandwidth of 300 MHz; and a diode detector 11 located at the end of the cascade. The output of detector 11 is the voltage across its terminals, representing the measured noise signal power. Those skilled in the art can also use other detectors to ensure the determination of signal strength.

[0034] Preferably, microwave isolators 4, 6, and 8 are placed between the amplifiers. Isolators with an insertion loss of 0.2 dB and isolation of 20 dB are used. This design makes it easier to protect the receiver chain from unwanted oscillations.

[0035] The above design is typical of a full-power radiometer and suffers from its typical drawbacks: dependence on temperature and operating conditions. These factors are too significant to allow for the determination of glucose concentration with sufficient accuracy in measuring tissue radiation without additional improvements.

[0036] The isolator can be replaced with a low-attenuation microwave attenuator (e.g., 2-3 dB). This approach is less efficient and may even increase the impact of chain noise, but it is advantageous for miniaturization.

[0037] In this invention, the effects of temperature and operating conditions are addressed digitally. It has been found that glucose concentration in the tissue affects both the noise generated by the tissue and the tissue's electrical parameters, which in turn affect the reflectivity at the connection between the tissue and antenna 2, as well as the tissue temperature. During measurement, the temperature reached by the antenna is essentially equal to the temperature of the tissue surface. This latter condition adds interference in the form of antenna intrinsic noise. Furthermore, noise interference from the receiver chain elements is measured using detector 11, which depends on their temperature and the current they consume. It has been demonstrated that the effects of the receiver chain's operating conditions (temperature and current) on the received noise signal power can be modeled well, just as blood glucose affects noise power. This can be accomplished in one step.

[0038] To address the impact of temperature variations on the gain of the radiometer chain, and the effect of these variations on the readings of the power detector 11, a contact temperature sensor (thermocouple) is provided at the following location in the receiver chain: - Antenna - On the grounded metallized side, on the patient temperature sensor 12, - Amplifiers 3, 5, 7, and 9 are on the housing, and on temperature sensors 13, 15, 18, and 20, respectively.

[0039] In addition, sensors 14, 16, 19, and 21 are provided for the power supply current of each of the amplifiers 3, 5, 7, and 9.

[0040] The signal outputs of sensors 12, 13, 15, 18, 20, 14, 16, 19, and 21, and the output of the power detector, are wired to processing system 17, which includes an analog-to-digital converter and a microprocessor for processing measurement data. Power is supplied to the radiometer chain elements, sensors, and acquisition module by a dedicated power module containing a lithium-ion battery and a set of voltage converters.

[0041] Those skilled in the art can readily propose various alternatives to the processing system 17, including the use of microprocessors, digital signal processors (DSPs), field-programmable gate arrays (FPGAs), and application-specific integrated circuits (ASICs) for specific signal processing tasks. Furthermore, system-on-a-chip (SoC) solutions can be employed; Raspberry Pi or single-board computers, Arduino-based microcontrollers, RISC-V processors, and ARM Cortex-M series microcontrollers have been tested to meet specific computational requirements. Specifically, factors considered include low-power microcontrollers for battery-powered applications. A distributed approach can also be used, sending sensor and detector signals to a remote cloud server for processing, thereby improving scalability, availability, and data management capabilities.

[0042] In this embodiment, processing system 17 acquires output signals from sensors 12, 13, 14, 15, 16, 18, 19, 20, 21 and detector 11, and converts the output signals into glucose concentration values ​​using a multivariate regression method and predefined transformation coefficients. A key observation is that the proposed set of coefficients allows for the differentiation of glucose concentration from other variable parameters affecting the total power of noise signals originating from tissue but measured using a passive radiometer—even with a simple total power radiometer structure. This set of coefficients primarily includes: the power of the noise signal, the power contribution introduced by impedance mismatch between the antenna and tissue, the thermal noise contribution of the antenna itself, the noise introduced by the receiver active elements (primarily shot noise caused by bias current), and the gain variation caused by the temperature of the active elements in the radiometer receiver chain. The noise introduced by the active elements is related to their respective temperatures and the current flowing through the semiconductor structure (primarily semiconductor junctions). The gain of the active elements is related to their operating point and depends on temperature. The temperature of the active elements (measured by a temperature sensor) is needed to model the gain variation, and the current is needed to model the noise generated by the active elements. The impedance of the tissue depends on the glucose concentration. Noise power originating from tissue is related to the surface temperature of the skin covering the tissue (tissue surface temperature) and the temperature of deeper tissues.

[0043] The transformation coefficients are determined by performing a series of measurements on a phantom with a known glucose concentration at various phantoms and ambient temperatures while varying the operating conditions of the receiver chain. These coefficients can also be determined by examining a group of patients under different conditions, or even examining a single patient for an extended period, while varying the operating conditions and adjusting the glucose concentration and verifying the glucose concentration in another measurement.

[0044] Alternatively, a known artificial model corresponding to the patient can be used as the basis for determining the coefficients. A tabular approach is also acceptable, where blood glucose values ​​in tissue 1 are determined based on the model employed during baseline measurements.

[0045] Blood glucose measurements should be performed prior to baseline measurements and model coefficient determination. This can be accomplished in a manner known in the art by measuring on phantom tissues with varying glucose concentrations, or by another method by simultaneously performing baseline measurements on the patient. Measurements performed on many patients or phantoms allow for averaging and determination of universal transformation coefficients. Measurements performed on a single patient can be used to obtain person-specific transformation coefficients and may yield more accurate results.

[0046] Importantly, the dataset obtained from the sensor makes it possible to "extract" the influence of glucose concentration from other factors affecting noise power and determine the transformation coefficients. This enables the determination of blood glucose in measurements that include not only noise power but also the temperature of the tissue surface, the temperature of the receiver chain elements, and the current consumed by the active elements of the receiver chain. This can be accomplished using multiple regression, or by employing a specific chain model, or even by using benchmark data to train a neural network running on the processing system 17, which receives the dataset from the sensor and detector and outputs the blood glucose measurement results. In this case, the transformation coefficients are the weighting coefficients of the neural network.

[0047] This invention can even be implemented by creating a lookup table containing glucose concentration values ​​corresponding to a specific set of measurement parameters. The entries in this table constitute the transformation coefficients.

[0048] The method according to the invention can be implemented in a general-purpose computer for input data or in the processing unit of a medical device. It should be emphasized that those skilled in the art, after studying the teachings of this specification, can routinely adapt it to various existing technologies, implementing it in digital devices integrated with radiometers, or, for example, running it remotely on a remote server. The method according to the invention can be implemented in existing digital devices (e.g., computers, microcomputers, or microcontrollers). Based on the teachings described above, those skilled in the art can routinely devise various hardware, software, or hybrid solutions.

[0049] The above embodiments have been discussed with reference to a simple total power radiometer; however, those skilled in the art will recognize that the present invention can be used with any passive radiometer including a total power radiometer, such as a Dicke radiometer and a correlated radiometer. While Dicke radiometers and correlated radiometers are more complex and more difficult to miniaturize, they allow for reduction of the influence of ambient temperature and conditions on the measurement results.

[0050] The computer program product according to the invention can be contained on a tangible data carrier, such as a CD, DVD, hard disk, or flash memory, on which data representing the computer program is recorded. Alternatively, the program can be stored in the "cloud" or intangible media such as a computer network connection.

[0051] The computer program includes instructions that, when executed by a computer, implement at least a portion of the methods described in any of the foregoing embodiments. The computer program may include various elements such as subroutines, functions, programs, object methods, object implementations, executable applications, applets, service applets, source code, object code, shared libraries, dynamically loaded libraries, and / or any other sequence of instructions intended to execute on a computer system.

[0052] It is important to emphasize that the above embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art will readily recognize that various alternative embodiments can be devised without departing from the scope of protection defined by the claims.

[0053] In the claims, reference numerals should not be considered as limiting the scope of the claims. The use of the verb "comprising" and its variations does not exclude the inclusion of additional elements or steps beyond those expressly mentioned in the claims. Similarly, the indefinite articles "a" or "an" preceding an element do not exclude the presence of a plurality of such elements. The method according to the invention can be implemented using computer hardware comprising multiple different components or by a single suitably programmed computer.

[0054] Industrial Applicability and Advantages of the Invention As a result of using the solution according to the present invention, additional advantages are obtained: - No additional microwave components, such as input circulators and directional couplers, are required, which facilitates miniaturization. - Single-chain replaces double-chain. - No additional reference noise source is required, and it typically has the necessary temperature stability. - No need to use input switches to continuously switch the input of the amplifier chain to the antenna output and noise source.

[0055] The device according to the present invention, which implements the method described herein, can be integrated into clothing and comes into contact with the skin of the subject. It is completely passive and does not emit any measurement signals to the patient's tissues. Therefore, it is completely safe, and the measurement system and method according to the present invention can be used for the prevention and treatment of diabetes, especially for pregnant women and children under 2 years of age.

Claims

1. A non-invasive, computer-implemented method for determining blood glucose concentration in patient tissue, the method being based on receiving wireless noise signals using an antenna held near the patient's skin, characterized in that... The wireless noise signal is received using a passive radiometer, and the method further includes the following steps: The steps to obtain the transform coefficients, The steps for measuring tissue surface temperature The step of measuring the temperature of the active element in the receiver chain of the radiometer. The step of measuring the current consumed by the active element of the receiver chain of the radiometer. The step of measuring the power of the wireless noise signal originating from the organization. The steps for determining the blood glucose concentration in the tissue are based on the following: The transformation coefficients, The measured tissue surface temperature value, The temperature of the active element in the receiver chain of the radiometer. The current consumed by the active element of the receiver chain of the radiometer, and The power of the wireless noise signal originating from the organization.

2. The method according to claim 1, wherein the method is implemented in a computer, and in the step of obtaining the transformation coefficients, predefined transformation coefficients are loaded from computer memory or downloaded from an external server.

3. The method of claim 1, wherein the transformation coefficient is determined based on a series of measurements performed on a set of tissues or phantoms with known glucose concentrations, the measurements being performed at different temperatures.

4. The method of claim 3, wherein the transformation coefficients are determined in a multivariate regression process, the multivariate regression process comprising minimizing the error in matching a glucose concentration baseline value with a value calculated from the transient characteristics of the radiometer, wherein the variables are: the tissue surface temperature, the temperature of the active element of the receiver chain of the radiometer, the current consumed by the active element of the receiver chain of the radiometer, and the power of the wireless noise signal.

5. The method according to any one of claims 1 to 4, wherein converting the measured value and transformation coefficient into blood glucose concentration comprises the following steps: Based on the transformation coefficient, the power measured using the radiometer, the temperature of the active element of the radiometer's receiving chain, and the current consumed by the active element of the radiometer's receiving chain, the power of the noise received by the antenna is determined. Based on the power of the noise received by the antenna, the transformation coefficient, and the tissue surface temperature, the power of the noise originating from the tissue and reaching the antenna, and the reflection coefficient at the junction between the antenna and the tissue, are determined. The glucose concentration is determined based on the determined reflection coefficient at the connection between the antenna and the tissue and the determined power of the noise originating from the tissue and reaching the antenna.

6. The method according to claim 1, 2, or 3, wherein the transformation coefficients are weight coefficients of a neural network processing a dataset, the dataset comprising: The measured surface temperature of the tissue, The temperature of the active element in the receiver chain of the radiometer. The current consumed by the active element of the receiver chain of the radiometer, and The power of the wireless noise signal originating from the organization.

7. The method according to any one of claims 1 to 6, wherein, The wireless noise signal was measured in the frequency band from 800 MHz to 24 GHz.

8. The method according to any one of claims 1 to 7, wherein, The measurements are performed in a frequency band with a width greater than or equal to 200 MHz.

9. The method according to claim 8, wherein, Measurements were performed in a frequency band with a width greater than or equal to 500 MHz.

10. A computer program product, running on a computer adapted to receive measurement data, characterized in that, The computer program product includes instructions that cause the method of any one of claims 1 to 9 to be executed.

11. A radiometer comprising an antenna (2) and a wireless receiving chain (3, 4, 5, 6, 7, 8, 9, 10) having a detector (11), said antenna (2) being adapted to be applied to the skin (1) of a patient and to receive wireless noise signals from subcutaneous tissue, characterized in that: The radiometer is a passive radiometer adapted to measure the power of noise signals originating from the tissue, and is equipped with: Regarding the temperature sensors (13, 15, 18, 20) of the active elements of the receiver chain of the radiometer, A sensor (12) located on the antenna (2) to measure the temperature of the tissue surface. And sensors (14, 16, 19, 21) regarding the current consumed by the active elements of the receiver chain of the radiometer.

12. The radiometer of claim 11, wherein the bandwidth of the antenna is at least 20% wider than the bandwidth of the receiver chain.

13. The radiometer of claim 11, wherein the receiver chain comprises a cascade of amplifiers (3, 5, 7, 9) separated by isolators (4, 6, 8).

14. The radiometer of claim 11, wherein the receiver chain comprises a cascade of amplifiers (3, 5, 7, 9) separated by attenuators, the attenuators having a rated attenuation of less than 3 dB.

15. A system for determining glucose concentration based on wireless signals, comprising a processing system (17) and a radiometer having an antenna (2) adapted to be applied to tissue, characterized in that: The radiometer is the radiometer according to any one of claims 11 to 14. Furthermore, the processing system (17) has been connected to the following components: Regarding the temperature sensors (13, 15, 18, 20) of the active elements of the receiver chain of the radiometer, A sensor (12) for the temperature of the tissue surface is placed on the antenna (2). The current measurement modules (14, 16, 19, 21) measure the current consumed by the active elements of the receiver chain of the radiometer. The processing system (17) is adapted to perform the method as described in any one of claims 1 to 9.

Images