Method for calibrating a biological value in a biological information measurement system according to the presence or absence of stabilization of the biological value

Abstract

The present invention provides a method for accurately calculating a calibration factor based on whether the user's biological value is unstable by determining the presence or absence of stability of the biological value from the difference between the blood biological value and the body fluid biological value. 【Solution means】 The present invention relates to a method for calibrating a user's biological value in a biological information measurement system. More specifically, when calculating a calibration factor using a reference biological value, if the stability of the biological value is determined from the difference between the blood biological value and the body fluid biological value and the biological value is unstable, instead of directly using the calibration factor calculated from the reference biological value, a corrected calibration factor with a weighted value is used to accurately determine the user's calibrated biological value from the biological value measured by the sensor. The present invention relates to a method for calibrating a biological value.

Description

Technical Field

[0001] The present invention relates to a method for calibrating a user's biological value in a biological information measurement system. More specifically, when calculating a calibration factor using a reference biological value, the presence or absence of stability of the biological value is determined from the difference between the blood biological value and the body fluid biological value. When the biological value is unstable, instead of directly using the calibration factor calculated from the reference biological value, a corrected calibration factor with a weighted value is used to accurately determine the user's calibrated biological value from the biological value measured by the sensor. The present invention relates to a method for calibrating a biological value.

Background Art

[0002] Diabetes is a chronic disease that frequently occurs in modern people. In the case of [country name], it has reached more than 2 million people, accounting for 5% of the total population.

[0003] Diabetes is caused by various factors such as obesity, stress, incorrect eating habits, and congenital inheritance. Insulin produced by the pancreas is absolutely or relatively insufficient, and the balance of sugar in the blood cannot be corrected, resulting in an absolute increase in sugar components in the blood and the onset of the disease.

[0004] Normally, blood contains a certain concentration of glucose, and tissue cells obtain energy from it.

[0005] However, when glucose increases more than necessary, it cannot be properly stored in the liver, muscles, or fat cells and accumulates in the blood. As a result, diabetic patients maintain much higher blood sugar levels than healthy people. Excessive blood sugar passes through tissues and is excreted as urine, resulting in a deficiency of sugars absolutely necessary for each tissue of the body and causing abnormalities in each tissue of the body.

[0006] Diabetes is characterized by few symptoms in the early stage. However, as the disease progresses, specific symptoms such as excessive thirst, excessive hunger, polyuria, weight loss, general fatigue, skin itching, and persistent non-healing wounds on the hands and feet may appear. If the disease progresses further, complications such as vision impairment, hypertension, kidney disease, stroke, periodontal disease, muscle spasms, neuralgia, and gangrene may occur.

[0007] In order to diagnose such diabetes and manage it so that it does not progress to complications, systematic blood glucose measurement and treatment must be carried out in parallel.

[0008] For the management of diabetes, it is necessary to steadily measure blood glucose. The demand for devices related to blood glucose measurement is steadily increasing. Through various studies, it has been confirmed that when diabetes patients strictly regulate their blood glucose, the occurrence of diabetes complications is significantly reduced. Therefore, it is very important for diabetes patients to regularly measure their blood glucose for blood glucose regulation.

[0009] For the blood glucose management of diabetes patients, a blood sampling type blood glucose meter (finger prick method) is generally mainly used. Although such a blood sampling type blood glucose meter is useful for the blood glucose management of diabetes patients, since only the result at the time of measurement appears, there is a problem that it is difficult to accurately grasp the frequently changing blood glucose values. In addition, since the blood sampling type blood glucose meter requires blood sampling each time for measuring blood glucose at any time of the day, there is a problem that the burden on diabetes patients for blood sampling is large.

[0010] To overcome the limitations of such blood sampling type blood glucose meters, a continuous blood glucose monitoring system (CGMS) that is inserted into the human body and measures blood glucose at intervals of moisture has been developed, and it can be used to easily manage diabetes patients and handle emergencies.

[0011] A continuous blood glucose measurement system includes a sensor transmitter that adheres to a user's body and measures biological values from interstitial fluid (ISF), and a communication terminal that outputs information regarding the transmitted biological values to the user. The sensor transmitter is equipped with a continuous blood glucose measurement sensor that is partially inserted into the human body. The sensor is inserted into the human body for a certain period of use, for example, approximately 15 days, and continuously measures biological values. The sensor transmitter periodically measures biological values from the body fluid, and a biological management application is installed on the communication terminal to periodically receive the biological values from the sensor transmitter and output information regarding the received biological values to the user.

[0012] The sensor of the sensor transmitter is continuously inserted into the skin during the period of use. However, the sensitivity of the sensor may vary depending on the body part where the sensor is inserted. Even if the sensor insertion position on the body part is the same, the sensitivity of the sensor will change over time. The biological values measured by the sensor transmitter will have an error from the user's actual biological values due to the change in sensitivity. In order to overcome such an error, a calibration factor must be applied to the measured biological values to calibrate the user's biological values.

[0013] In order to provide accurate biological values to the user, the biological values received from the sensor transmitter must be initially calibrated, and then continuously calibrated at regular calibration intervals during the period of use of the sensor transmitter. More specifically, during the period of use of the sensor transmitter, a calibration factor is calculated using the reference biological values measured through a separate measuring instrument and the biological values received from the sensor transmitter at each calibration interval, and the biological values received from the sensor transmitter are calibrated by applying the calibration factor until the next calibration interval arrives.

[0014] The biological value calibrated in this way is a biological value of body fluid measured from the user's interstitial fluid (ISF), and there is a time delay between the biological value of body fluid measured from the body fluid and the biological value of blood measured from blood (blood or plasma).

[0015] Figure 1 is a drawing for explaining the delay model between the biological value of body fluid and the biological value of blood. As shown in Figure 1, the blood vessel and the body fluid are separated by the capillary barrier, and a time delay occurs for glucose to diffuse from the blood vessel to the body fluid by diffusion. Interstitial fluid blood glucose value (I glu ) is calculated as shown in the following mathematical formula (1).

[0016] Mathematical formula (1)

Number

[0017] Here, I sig is the normal current value as the sensor signal indicating the biological value measured by the sensor, α is the calibration factor, and b means the offset.

[0018] The final blood biological value is calculated using the delay model between the body fluid biological value and the blood biological value as shown in the following mathematical formula (2) and the state transition matrix of the Kalman filter as shown in the mathematical formula (3).

[0019] Mathematical formula (2)

Number

[0020] Here, B is the final blood biological value, and τ means the time delay.

[0021] Mathematical formula (3)

Number

[0022] In addition to the time delay related to the delay model between such body fluid biological values and blood biological values, time delays such as the delay due to the physical structure of the sensor itself and the calculation delay required to calculate the body fluid biological value from the sensor signal occur.

[0023] Therefore, a calibration factor is calculated from a sensor signal that is time-delayed, for example, by 1 minute to 15 minutes, from the time when the reference biological value and the reference biological value were measured. When calculating the calibration factor, in a state where the biological value is stable, there is no significant difference between the reference biological value and the sensor signal that is time-delayed and mapped to the reference biological value. However, the time delay of the sensor signal varies depending on the type of sensor or the user. In a state where the biological value is unstable, the sensor signal that is time-delayed and mapped to the reference biological value is not stable. Therefore, there is a problem that the calibration factor cannot be accurately calculated using the reference biological value measured in a state where the biological value is unstable.

[0024] On the other hand, after the sensor is inserted into the body, it takes a certain amount of time for the sensor to stabilize. Before the sensor stabilizes, the reliability of the biological value measured is relatively low. After that, as the sensor stabilizes, the reliability of the biological value measured by the sensor relatively increases. Therefore, when calculating the calibration factor using the reference biological value measured while the user's biological value is unstable, it is necessary to calculate the calibration factor differently considering the degree of stabilization of the sensor. Summary of the Invention Problems to be Solved by the Invention

[0025] The present invention is for solving the problems of the conventional calibration factor calculation method described above. The object to be achieved by the present invention is to provide a method for accurately calculating the calibration factor by determining the presence or absence of stability of the biological value from the difference between the blood biological value and the body fluid biological value, depending on whether the user's biological value is unstable or not.

[0026] Another object to be achieved by the present invention is to provide a method for accurately calculating a calibration factor by dividing the entire usage period of a sensor into a number of calibration intervals when calculating the calibration factor using a reference biological value, and considering the degree of stabilization of the sensor according to the calibration interval.

Means for Solving the Problems

[0027] To achieve the object of the present invention, a method for calibrating a biological signal according to the present invention includes: determining whether a reference biological value is input; calculating a first biological parameter and a second biological parameter at the time when the reference biological value is input; determining whether a correction condition is satisfied based on the first biological parameter and the second biological parameter; calculating a corrected calibration factor according to whether the correction condition is satisfied, and calculating a calibrated biological value from the biological signal measured by the sensor using the corrected calibration factor.

[0028] The method for calibrating a biological signal according to the present invention is characterized in that when the correction condition is not satisfied, the current calibration factor is calculated from the input reference biological value, and the calibrated biological value is calculated from the biological signal using the current calibration factor until the next reference biological value is input.

[0029] Preferably, the step of calculating the blood calibrated biological value according to an embodiment of the present invention includes: when the correction condition is satisfied, calculating the current calibration factor from the input reference biological value; determining the calibration interval to which the time point when the reference biological value is input belongs; calculating a corrected calibration factor from the current calibration factor so as to be different according to the calibration interval to which the time point when the reference biological value is input belongs based on the determined calibration interval; calculating a body fluid calibrated biological value in the body fluid using the biological signal measured by the sensor and the corrected calibration factor until the next reference biological value is input; and calculating a blood calibrated biological value by applying the body fluid calibrated biological value to a conversion model.

[0030] In the method for calibrating a biological signal according to the present invention, the calibration interval is characterized in that the entire usage period of the sensor is divided into a first interval, a second interval, and a third interval according to the passage of time based on the time point when the sensor is inserted into the body.

[0031] In the method for calibrating a biological signal according to the present invention, when the time point at which the reference biological value is input belongs to the first section, the current calibration factor is calculated as the corrected calibration factor.

[0032] In the method for calibrating a biological signal according to the present invention, when the time point at which the reference biological value is input belongs to the second section, the corrected calibration factor is calculated by applying a first weighting value to the current calibration factor.

[0033] In the method for calibrating a biological signal according to the present invention, when the time point at which the reference biological value is input belongs to the third section, the corrected calibration factor is calculated by applying a second weighting value to the current calibration factor.

[0034] In the method for calibrating a biological signal according to the present invention, the first biological parameter is the interstitial fluid (ISF) blood glucose value, and the second biological parameter is the blood (blood or plasma) blood glucose value.

[0035] Preferably, the method for calibrating a biological signal according to the present invention further includes calculating an average value of previous corrected calibration factors calculated in the third section based on the time point at which the reference biological value is input, and recorrecting the corrected calibration factor based on the average value.

[0036] Preferably, the step of recorrecting the corrected calibration factor according to an embodiment of the present invention includes calculating a correction critical range based on the average value, determining whether the corrected calibration factor is outside the correction critical range, and recorrecting the corrected calibration factor according to whether the corrected calibration factor is outside the correction critical range to determine the final calibration factor, and calculating a calibrated biological value using the final calibration factor.

[0037] In the method for calibrating a biological signal according to the present invention, when the corrected calibration factor is outside the correction critical range, the corrected calibration factor is recorrected to the correction critical range to determine the final calibration factor.

[0038] In the method for calibrating a biological signal according to the present invention, when the corrected calibration factor is within the corrected critical range, the corrected calibration factor is determined as the final calibration factor.

[0039] Preferably, in one embodiment of the present invention, the step of re-correcting the corrected calibration factor includes calculating the difference between the corrected calibration factor and the average value, calculating a compensation value from the difference between the corrected calibration factor and the average value, and re-correcting the corrected calibration factor with the compensation value to calculate the final calibration factor, and calculating a calibrated biological value using the final calibration factor.

Effect of the Invention

[0040] In the method for calibrating a biological signal according to the present invention, when calculating a calibration factor using a reference biological value, the presence or absence of stability of the biological value is determined from the difference between the blood biological value and the body fluid biological value. When the biological value is unstable, the calibration factor calculated from the reference biological value is not used as it is, and by giving a weighting value to the calibration factor, the user's biological value can be accurately determined from the biological signal.

[0041] Further, in the method for calibrating a biological signal according to the present invention, when calculating a calibration factor using a reference biological value, the entire usage period of the sensor is divided into a number of calibration intervals, and the calibration factor is corrected in consideration of the degree of stabilization of the sensor according to the calibration interval to which the time point when the reference biological value is input belongs, so that the user's biological value can be accurately calculated from the biological signal of the sensor.

[0042] Further, in the method for calibrating a biological signal according to the present invention, the average value of the calibration factors in the section where the sensor is stabilized is calculated, and the calibration factor is re-corrected in consideration of the difference between the corrected calibration factor and the average value, so that the user's biological value can be accurately calculated from the biological signal of the sensor in the section where the sensor is stabilized.

Brief Description of the Drawings

[0043]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0044] It should be noted that the technical terms used in the present invention are merely used to explain specific embodiments and are not intended to limit the present invention. Also, the technical terms used in the present invention should be interpreted in the meaning generally understood by those with ordinary knowledge in the technical field to which the present invention belongs, unless otherwise defined specifically in the present invention, and should not be interpreted in an overly comprehensive meaning or an overly narrowed meaning. Further, when the technical terms used in the present invention are incorrect technical terms that cannot accurately represent the idea of the present invention, they should be understood as being replaced by technical terms that can be correctly understood by those skilled in the art.

[0045] In addition, the singular expressions used in the present invention include plural expressions unless the context clearly indicates otherwise. In the present invention, terms such as "composed of" or "including" should not be construed as necessarily including all of the plurality of components or steps described in the invention. Some of the components or steps may not be included, or it should be construed that additional components or steps can be further included.

[0046] It should also be noted that the attached drawings are only for facilitating the understanding of the idea of the present invention, and the idea of the present invention should not be construed as being limited by the attached drawings.

[0047] With reference to the attached drawings below, a method for calibrating a biological signal according to the degree of stabilization of a biological value according to the present invention will be considered more specifically.

[0048] FIG. 2 is a schematic diagram illustrating a biological value measurement system according to an embodiment of the present invention.

[0049] Hereinafter, blood glucose level will be described as an example of a biological value, and reference blood glucose level will be described as an example of a reference biological value. However, various biological values other than blood glucose level can be measured depending on the field to which the present invention is applied.

[0050] Referring to FIG. 2, a biological value measurement system 1 according to an embodiment of the present invention includes a sensor transmitter 10 and a communication terminal 30.

[0051] The sensor transmitter 10 adheres to the body. When the sensor transmitter 10 adheres to the body, one end of the sensor of the sensor transmitter 10 is inserted into the skin to measure a biological signal indicating the blood glucose level, that is, a blood glucose signal, periodically from the body fluid of the human body.

[0052] The communication terminal 30 receives a blood glucose signal from the sensor transmitter 10, calibrates the received blood glucose signal with a calibration factor to perform unit conversion to a body fluid blood glucose value, and then calculates a blood glucose value from the body fluid blood glucose value using a delay model between the body fluid blood glucose value and the blood blood glucose value, and can display the blood glucose value to the user. A terminal capable of communicating with the sensor transmitter 10, such as a smartphone, a tablet PC, or a notebook computer, can be used. Of course, the communication terminal 30 is not limited to these, and any type of terminal can be used as long as it is a terminal on which programs and applications can be installed including a communication function.

[0053] In the present invention, a blood glucose value obtained by applying a calibration factor to a blood glucose signal measured by the sensor transmitter 10 and performing unit conversion is referred to as a body fluid blood glucose value, and a blood glucose value calculated from the body fluid blood glucose value using a delay model between the body fluid blood glucose value and the blood blood glucose value is referred to as a blood blood glucose value. On the other hand, the body fluid blood glucose value or the blood blood glucose value calculated by applying a calibration factor to the blood glucose signal is collectively referred to as a calibrated blood glucose value. On the other hand, the blood glucose signal received from the sensor transmitter is also referred to as a measured blood glucose value.

[0054] The sensor transmitter 10 transmits a blood glucose signal to the communication terminal 30 periodically at the request of the communication terminal 30 or at set times. However, between the sensor transmitter 10 and the communication terminal 30, for data communication, the sensor transmitter 10 and the communication terminal 30 can be communicatively connected to each other by wire using a USB cable or the like, or can be communicatively connected by a wireless communication method such as infrared communication, NFC communication, Bluetooth (registered trademark).

[0055] When communication is connected between the sensor transmitter 10 and the communication terminal 30, after the initial stabilization of the sensor transmitter 10, an initial calibration factor is calculated using a reference blood glucose value measured through a separate blood glucose meter (not shown), and initial calibration of the blood glucose signal is performed using the initial calibration factor. Thereafter, the communication terminal 30 calibrates the blood glucose signal received from the sensor transmitter 10 with the initial calibration factor and outputs and provides the calibrated blood glucose value to the user.

[0056] Here, the initial stabilization can be determined to be initially stabilized after a certain period of time after the sensor is inserted into the body, for example, after 2 hours have elapsed, or the presence or absence of initial stabilization can be determined based on the blood glucose signal. Here, the initial stabilization is the minimum stabilization time and conditions necessary to notify the user of the calibrated blood glucose value as soon as possible after the sensor is inserted into the body. Actually, until the sensor is actually stabilized, additional time, for example, a time period of about 1 day to 10 days may be required.

[0057] After the initial stabilization, in order to accurately calibrate the blood glucose signal in the sensor transmitter 10, the communication terminal 30 calculates a new calibration factor using the reference blood glucose value measured through a separate blood glucose meter at each calibration cycle during the usage period of the sensor transmitter 10, and calibrates the blood glucose signal received from the sensor transmitter using the new calibration factor.

[0058] Preferably, the calibration cycle can be changed according to the progress of stabilization. For example, after the initial stabilization, calibration is performed at 12-hour intervals, and thereafter, calibration can be performed at 24-hour or 48-hour intervals according to the progress of stabilization.

[0059] FIG. 3 is a functional block diagram for explaining the calibration device for biological signals according to the present invention.

[0060] The calibration device for the corresponding blood glucose signal is implemented by a communication terminal such as a smart terminal that communicates with the sensor transmitter and notifies the user of the calibrated blood glucose value, or can be implemented through a separate receiving device.

[0061] Referring to FIG. 3 for more specific consideration, when the calibration cycle arrives according to the calibration cycle stored in the storage unit 150, the calibration notification unit 130 provides a calibration notification to the user through the user interface unit 110.

[0062] Preferably, when the calibration period arrives, the calibration notification unit 130 extracts the biological parameters stored in the storage unit 150, compares the extracted biological parameters with the calibration limit conditions, and if the calibration limit conditions are met, does not provide a calibration notification to the user interface unit 110 or can deactivate the calibration icon through which a calibration command can be input to the user interface unit 110. Here, the biological parameters are the body fluid blood glucose level, the blood blood glucose level, the change rate of the blood glucose level, the change speed of the blood glucose level, etc., and the calibration limit conditions can be whether the blood glucose level exceeds the critical limit blood glucose level or whether the change rate of the calibration blood glucose level exceeds the critical limit change rate.

[0063] When the calibration limit conditions are not met and a reference blood glucose level is input through the user interface unit 110, the calibration unit 170 determines the calibration interval to which the time point at which the reference blood glucose level is input belongs, or determines whether the correction condition of the calibration factor is satisfied based on the biological parameters at the time point when the reference blood glucose level was input. The calibration unit 170 calculates a calibration factor based on whether the correction condition of the calibration factor is satisfied and the calibration interval to which the time point at which the reference blood glucose level is input belongs, and calculates a calibrated blood glucose level using the calculated calibration factor.

[0064] When a reference blood glucose level is input to calculate a calibration factor, the calibration unit 170 determines the measured blood glucose value corresponding to the input time of the reference blood glucose level among the measured blood glucose values received through the transceiver unit 190, and generates a calibration pair consisting of the reference blood glucose level and the corresponding measured blood glucose value. The calibration unit 170 calculates a calibration factor using the calibration pair. Depending on the field to which the present invention is applied, the calibration unit 170 can calculate a calibration factor using the current calibration pair consisting of the input reference blood glucose level and the measured blood glucose value corresponding to the reference blood glucose level, but in order to calculate an accurate calibration factor, the calibration factor can be calculated in a regressive manner using the current calibration pair and past calibration pairs.

[0065] When the reference blood glucose value is input, the calibration unit 170 can determine whether the correction condition of the calibration factor is satisfied, and can use the calibration factor calculated based on the calibration interval to which the time point when the reference blood glucose value is input belongs as it is, or can correct the calculated calibration factor.

[0066] After the reference blood glucose value is input, the calibration unit 170 calibrates the measured blood glucose value received using the calibration factor to calculate a calibrated blood glucose value, and provides the calculated calibrated blood glucose value to the user through the user interface unit 110.

[0067] FIG. 4 is a functional block diagram for explaining the calibration unit according to the present invention.

[0068] More specifically, referring to FIG. 4, when the reference blood glucose value is input, the calibration interval determination unit 173 determines the calibration interval to which the time point when the reference blood glucose value is input belongs based on the time point when the reference blood glucose value is input.

[0069] On the other hand, the calibration condition determination unit 175 determines the first biological parameter and the second biological parameter at the time when the reference blood glucose value is input, and determines whether the correction condition of the calibration factor is satisfied from the first biological parameter and the second biological parameter. The calibration factor calculation unit 177 calculates the current calibration factor from the current calibration pair or the past calibration pair.

[0070] Based on the calibration interval to which the time point when the reference blood glucose value is input belongs, and whether the correction condition of the calibration factor is satisfied from the first biological parameter and the second biological parameter at the time when the reference blood glucose value is input, the calibration factor determination unit 171 determines the current calibration factor calculated by the calibration factor calculation unit 177 as the calibration factor as it is, or causes the calibration factor correction unit 178 to correct the current calibration factor, and determines the corrected calibration factor as the calibration factor.

[0071] When the calibration factor determination unit 171 satisfies the calibration factor correction condition at the time when the reference blood glucose value is input, it requests the calibration factor correction unit 178 to correct the current calibration factor. When the calibration factor correction unit 178 receives the correction request for the current calibration factor, it gives a weighting value to the current calibration factor according to the calibration interval to which the time point when the reference blood glucose value is input belongs, and calculates the corrected calibration factor.

[0072] Depending on the degree of progress of stabilization, when the degree of stabilization of the sensor is high, it is necessary to maintain the calibration factor so that it does not change significantly. However, when it is determined that the time point when the reference blood glucose value is input is a calibration interval with high sensor stabilization, the calibration factor correction unit 178 can re-correct the corrected calibration factor based on the average value of the previous calibration factors in the calibration interval with high sensor stabilization calculated by the average value calculation unit 179.

[0073] In this way, when the calibration factor determination unit 171 does not satisfy the correction condition based on whether the correction condition of the calibration factor is satisfied at the time when the reference blood glucose value is input, it uses the calculated current calibration factor as it is. However, when the correction condition of the calibration factor is satisfied at the time when the reference blood glucose value is input, the calibration factor is corrected by giving different weighting values to the current calibration factor according to the calibration interval to which the time point when the reference blood glucose value is input belongs, or the corrected calibration factor can be re-corrected based on the average value of the previous calibration factors in the calibration interval with high sensor stabilization.

[0074] FIG. 5 is a flowchart for explaining the calibration method of the blood glucose signal according to the present invention.

[0075] More specifically, referring to FIG. 5, it is determined whether the calibration cycle arrives or whether the reference blood glucose value is input at the request of the user regardless of the calibration cycle (S110).

[0076] When a reference blood glucose value is input, it is determined which calibration period the time point at which the reference blood glucose value is input during the entire usage period of the sensor belongs to (S130). Here, the calibration period can divide the entire usage period of the sensor into a first period, a second period, and a third period according to the passage of time based on the time point when the sensor is inserted into the body. The first period is a period in which the degree of stabilization of the sensor after insertion is low, the second period is a period in which the degree of stabilization of the sensor after the first period has elapsed has further progressed, and the third period means a period in which the degree of stabilization of the sensor after the second period has elapsed is higher than that of the second period. Depending on the field to which the present invention is applied, the entire usage period of the sensor can be divided into various and numerous calibration periods, which fall within the scope of the present invention.

[0077] Based on the calibration period to which the time point at which the reference blood glucose value is input belongs, a calibration factor is calculated (S150), the measured blood glucose value is calibrated using the calculated calibration factor to calculate a calibrated blood glucose value, and the calculated calibrated blood glucose value is provided to the user (S170).

[0078] In the calibration period to which the time point at which the reference blood glucose value is input belongs, the calibration factor can be calculated differently depending on whether the correction condition of the calibration factor is satisfied at the time point when the reference blood glucose value is input.

[0079] FIG. 6 is a drawing for explaining an example of inputting calibration information according to a calibration cycle. Here, the calibration information is the reference blood glucose value of the user measured with a test strip through a separate blood glucose meter.

[0080] Referring to FIG. 6, at time point t when the sensor of the sensor transmitter is initially stabilized 1 initial calibration information is input to the communication terminal. Here, the initial calibration information can be input multiple times in order to accurately calculate the calibration factor. The communication terminal calculates an initial calibration factor using the initial calibration information and the blood glucose value measured by the sensor transmitter, and calibrates the measured blood glucose value received from the sensor transmitter using the initial calibration factor to calculate the calibrated blood glucose value of the user.

[0081] After the sensor of the sensor transmitter is initially stabilized, new calibration information is periodically input into the communication terminal until the end of the service life of the sensor transmitter, preferably at calibration intervals such as 12 hours or 24 hours. After the sensor of the sensor transmitter is initially stabilized, the sensor is, for a certain period of time, at a first calibration interval T of 12 hours 1 at which new calibration information is input, and thereafter, new calibration information may be input at a second calibration interval T of 24 hours, 48 hours, etc. for the sensor of the sensor transmitter. 2

[0082] When the sensor is in the same environment and conditions, during manufacturing, after being inserted into the body, the sensor will have a certain sensitivity drift characteristic. Based on such sensitivity drift characteristics, the calibration intervals can be set to be different from each other according to the manufacturing environment of the sensor.

[0083] FIG. 7 illustrates an example of a calibration interval that divides the entire service life of the sensor according to the present invention.

[0084] Referring to FIG. 7 for consideration, the first interval T is is a section where the stabilization degree of the sensor after initial stabilization is low, and the second interval T fs is a section where the stabilization information of the sensor after the first interval has passed is intermediate, and the third interval T es is a section where the stabilization degree of the sensor after the second interval has passed is higher than that of the second interval.

[0085] Depending on the field to which the present invention is applied, the first interval can be set from 0.5 day to 1 day from the time when the sensor is inserted into the body, the second interval can be set from 3 days to 5 days from the time when the first interval ends, and the third interval can be set to the remaining service life of the sensor from the time when the second interval ends. Depending on the field to which the present invention is applied, the first interval, the second interval, and the third interval can be set to different times, which belongs to the scope of the present invention.

[0086] ​FIG. 8 is a flowchart for explaining an example of a method for calculating a calibration factor in the present invention.

[0087] Referring to FIG. 8 for more specific consideration, it is determined whether the calibration section to which the time point when the reference blood glucose value is input belongs is the first section (S171). When the calibration section to which the time point when the reference blood glucose value is input belongs is the first section, the current calibration factor calculated from the reference blood glucose value and the measured blood glucose value corresponding to the time point when the reference blood glucose value is input is calculated as the corrected calibration factor (S179).

[0088] On the other hand, when the calibration section to which the time point when the reference blood glucose value is input belongs is not the first section, it is determined whether the calibration section to which the time point when the reference blood glucose value is input belongs is the second section (S173). When the calibration section to which the time point when the reference blood glucose value is input belongs is the second section, it is determined whether the correction condition of the calibration factor is satisfied at the time point when the reference blood glucose value is input (S175). When the calibration section to which the time point when the reference blood glucose value is input belongs is the second section and the correction condition of the calibration condition is not satisfied at that time, the current calibration factor is calculated as the corrected calibration factor (S179). However, when the calibration section to which the time point when the reference blood glucose value is input belongs is the second section and the correction condition of the calibration condition is satisfied at that time, a first weighting value is given to the current calibration factor to calculate the corrected calibration factor (S176), (S179).

[0089] For example, when the calibration section to which the time point when the reference blood glucose value is input belongs is the second section and the correction condition of the calibration condition is satisfied at this time, the corrected calibration factor can be calculated as in the following mathematical formula (1).

[0090] Mathematical formula (1)

Equation

[0091] Here, CF R , CF C , CF P , α 1 mean the corrected calibration factor, the current calibration factor, the previous calibration factor, and the first weighting value, respectively.

[0092] Here, the first weighting value can be set to be from 0.3 to 0.6. Here, the first weighting value can be calculated in proportion to the difference value between the first biological parameter and the second biological parameter within the range of the already set first weighting value.

[0093] On the other hand, when the calibration interval to which the time point at which the reference blood glucose value is input belongs is not the second interval, it is determined that the calibration interval to which the time point at which the reference blood glucose value is input belongs is the third interval, and it is determined whether the correction condition of the calibration factor is satisfied at the time point at which the reference blood glucose value is input (S177). When the calibration interval to which the time point at which the reference blood glucose value is input belongs is the third interval and the correction condition of the calibration factor is not satisfied at that time, the current calibration factor is calculated as the corrected calibration factor (S179). However, when the calibration interval to which the time point at which the reference blood glucose value is input belongs is the third interval and the correction condition of the calibration factor is satisfied at that time, the second weighting value is given to the current calibration factor to calculate the corrected calibration factor (S178), (S179).

[0094] For example, when the calibration interval to which the time point at which the reference blood glucose value is input belongs is the third interval and the calibration parameter satisfies the calibration condition at this time, the corrected calibration factor can be calculated as in the following mathematical formula (2).

[0095] Mathematical formula (2)

Equation

[0096] Here, CF R 、CF C 、CF P 、α 2 respectively mean the corrected calibration factor, the current calibration factor, the previous calibration factor, and the second weighting value.

[0097] Here, the second weighting value can be set to be from 0.6 to 0.9. Here, the second weighting value can be calculated in proportion to the difference value between the first biological parameter and the second biological parameter within the range of the already set second weighting value.

[0098] Here, the correction conditions can be set to be different or the same depending on the calibration interval as conditions for determining whether the user's biological value is unstable.

[0099] For example, an example of the correction conditions is as follows. 1) When the reference blood glucose value exceeds the upper critical blood glucose value and at the same time the current calibration factor is larger than the previous calibration factor 2) When the reference blood glucose value is smaller than the lower critical blood glucose value and the previous calibration factor is larger than the current calibration factor 3) When the difference value between the first biological parameter and the second biological parameter exceeds the critical value

[0100] In the present invention, the first biological parameter can be the blood glucose value, and the second biological parameter can be the body fluid glucose value, but the blood glucose value can be calculated through the delay model between the aforementioned blood glucose value and the body fluid glucose value.

[0101] In a state where the user's biological value is stable, the difference between the blood glucose value and the body fluid glucose value is not large, but it can be confirmed that there is a significant difference between the blood glucose value and the body fluid glucose value in a state where the user's biological value is unstable. Therefore, when the difference between the blood glucose value and the body fluid glucose value exceeds the critical value, it can be determined that the user's biological value is in an unstable state.

[0102] FIG. 9 is a flowchart for explaining an example of the stage of re - correcting the corrected calibration factor in the present invention.

[0103] When the calibration interval to which the time point when the reference blood glucose value is input belongs is the third interval, in the third interval, since the degree of stabilization of the sensor is high, it is necessary to maintain the calibration factor so that it does not change significantly. For this purpose, the corrected calibration factor can be re - corrected to follow the average value of the calibration factors calculated in the third interval.

[0104] Considering more specifically with reference to FIG. 9, the average value of the previous correction factors in the third interval is calculated based on the time point when the reference blood glucose value is input (S211), and the correction critical range is calculated based on the calculated average value (S213). Here, the previous correction factors are the correction factors obtained previously based on the time point when the reference blood glucose value is input.

[0105] It is determined whether the correction factor is outside the correction critical range (S215), and the correction factor is re-corrected according to whether the correction factor is outside the correction critical range to determine the final correction factor (S217).

[0106] That is, when the correction factor exists within the correction critical range, the correction factor is determined as the final correction factor. However, when the correction factor is outside the correction critical range, the correction factor is re-corrected to the correction critical range to determine the final correction factor (S219). When the final correction factor is determined, the calibrated blood glucose value is calculated using the final correction factor.

[0107] For example, when the correction factor exceeds the upper limit line of the correction critical range, the correction factor is re-corrected to the upper limit line of the correction critical range, and when the correction factor exceeds the lower limit line of the correction critical range, the correction factor is re-corrected to the lower limit line of the correction critical range.

[0108] FIG. 10 is a flowchart for explaining another example of the stage of re-correcting the correction factor in the present invention.

[0109] Considering more specifically with reference to FIG. 10, the average value of the previous correction factors in the third interval is calculated based on the time point when the reference blood glucose value is input (S221), and a compensation value is calculated based on the calculated average value (S223).

[0110] Here, the compensation value can be calculated considering the difference between the correction factor and the average value so that the correction factor follows the average value, and the compensation value can be calculated as shown in the following mathematical formula (4).

[0111] Mathematical formula (4)

Number

[0112] Here, CF R2 、CF R 、CF M 、α 3 respectively represent the final calibration factor, the correction calibration factor, the average value, and the third weighting value, and the following formula represents the compensation value.

[0113]

Number

[0114] Here, the third weighting value can be set to 0.7 to 0.9.

[0115] For example, when the third weighting value is set to 0.8, the correction calibration factor is 10, and the average value is 8, the final correction factor can be re-corrected to follow the average value as the following formula.

[0116]

Number

[0117] On the other hand, the above-described embodiments of the present invention can be created as a program executable by a computer and can be embodied in a general-purpose digital computer that operates the program using a computer-readable recording medium.

[0118] The computer-readable recording medium includes storage media such as magnetic storage media (e.g., ROM, floppy disk, hard disk, etc.), optical reading media (e.g., CD-ROM, DVD, etc.), and carrier waves (e.g., transmission through the Internet).

[0119] The present invention has been described with reference to the embodiments illustrated in the drawings, which are merely exemplary, and those having ordinary knowledge in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical idea of the appended claims for registration.

Claims

1. A step of determining whether a reference biological value is input, A step of acquiring a first biological parameter and a second biological parameter when the reference biological value is input, A step of determining whether a correction condition is satisfied based on the first biological parameter and the second biological parameter, A step of obtaining a correction calibration factor according to whether the correction condition is satisfied, and obtaining a calibrated biological value from a biological signal using the correction calibration factor, A method for calibrating a biological signal, characterized by including the above steps.

2. The step of obtaining a calibrated biological value from the biological signal is, When the correction condition is not satisfied, Calculating a current calibration factor from the input reference biological value, The method for calibrating a biological signal according to claim 1, including the step of obtaining the calibrated biological value from the biological signal based on the current calibration factor.

3. The step of obtaining a calibrated biological value from the biological signal is, When the correction condition is satisfied, A step of obtaining a current calibration factor from the input reference biological value, A step of determining a calibration interval to which the time point when the reference biological value is input belongs, A step of obtaining a correction calibration factor from the current calibration factor based on the determined calibration interval, A step of measuring the biological signal using a sensor, A step of obtaining a body fluid calibrated biological value based on the biological signal and the correction calibration factor, A step of obtaining a blood calibrated biological value based on the body fluid calibrated biological value, The method for calibrating a biological signal according to claim 1, including the above steps.

4. The calibration interval is divided into a first interval, a second interval after the first interval, and a third interval after the second interval. The method for calibrating a biological signal according to claim 3.

5. When the time point when the reference biological value is input belongs to the first interval, The correction calibration factor is the current calibration factor. The method for calibrating a biological signal according to claim 4.

6. When the time point when the reference biological value is input belongs to the second interval, The step of obtaining the correction calibration factor from the current calibration factor is, The method for calibrating a biological signal according to claim 4, including the step of applying a first weighting value to the current calibration factor.

7. When the time point when the reference biological value is input belongs to the third interval, The step of obtaining the correction calibration factor from the current calibration factor is, The method for calibrating a biological signal according to claim 4, including the step of applying a second weighting value to the current calibration factor.

8. The calibration method of the biological signal according to claims 1 to 7, wherein the first biological parameter is the interstitial fluid (ISF) blood glucose value, and the second biological parameter is the blood (blood or plasma) blood glucose value.

9. When the time point at which the reference biological value is input belongs to the third interval, obtaining at least one or more previous corrected calibration factors; obtaining an average value of the previous corrected calibration factors; further comprising re-correcting the corrected calibration factor based on the average value, the calibration method of the biological signal according to claim 4.

10. The step of re-correcting the corrected calibration factor obtaining a correction critical range based on the average value; determining whether the corrected calibration factor is outside the correction critical range; re-correcting the corrected calibration factor according to whether the corrected calibration factor is outside the correction critical range; including obtaining a final calibration factor based on the re-corrected corrected calibration factor; further comprising calculating the calibrated biological value based on the final calibration factor, the calibration method of the biological signal according to claim 9.

11. When the corrected calibration factor is outside the correction critical range, the calibration method of the biological signal according to claim 10, further comprising re-correcting the corrected calibration factor so that the corrected calibration factor belongs to the correction critical range.

12. When the corrected calibration factor is within the correction critical range, the corrected calibration factor is the final calibration factor, the calibration method of the biological signal according to claim 10.

13. The step of re-correcting the corrected calibration factor obtaining a difference between the corrected calibration factor and the average value; obtaining a compensation value based on the difference between the corrected calibration factor and the average value; re-correcting the corrected calibration factor based on the compensation value; including obtaining a final calibration factor based on the re-corrected corrected calibration factor; obtaining the calibrated biological value based on the final calibration factor; further comprising, the calibration method of the biological signal according to claim 9.

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