Calibration Method and System for a Blood Oxygen Simulator to Adapt to Different Blood Oxygen Meters

Abstract

This application belongs to the field of blood oxygen saturation detection, and particularly relates to a calibration method and system for a blood oxygen simulator to adapt to different blood oxygen meters. This application obtains the blood oxygen detection parameter signal output by the blood oxygen meter, extracts the first signal and the second signal based on the obtained blood oxygen detection parameter signal. The blood oxygen simulator outputs the third signal and the fourth signal according to the received first signal and second signal. The blood oxygen meter receives the third signal and the fourth signal to detect the blood oxygen saturation. By using the method of segmental calibration of the blood oxygen saturation, the measured blood oxygen saturation is segmentally calibrated. This calibration method is not limited by the blood oxygen curve, and is simple to operate, and can quickly make the blood oxygen simulator adapt to the blood oxygen meter.

Description

Technical Field

[0001] This application relates to the field of blood oxygen saturation detection, and particularly to a calibration method and system for a blood oxygen simulator to adapt to different blood oxygen meters. Background Art

[0002] With the development of medical simulation technology, medical simulation case teaching has become more realistic. In medical simulation case teaching, real detection devices are often used to detect vital sign parameters, such as sphygmomanometers, electrocardiogram monitors, blood oxygen meters, etc. A blood oxygen meter is a detection device for detecting the blood oxygen saturation of the human body. Blood oxygen saturation reflects the concentration of blood oxygen in the blood and is an important physiological parameter of the respiratory and circulatory systems. Many clinical diseases can lead to insufficient oxygen supply, affecting cell metabolism, and even endangering life in severe cases. Therefore, the accuracy of blood oxygen saturation detection is crucial for the diagnosis and treatment of diseases.

[0003] On a medical model, a blood oxygen simulator is usually set up to detect the blood oxygen saturation of a simulated person with a real blood oxygen meter. However, since the blood oxygen detection parameter outputs of blood oxygen meters from different manufacturers and models are different, there is a deviation between the detected values and the blood oxygen saturation truly reflected by the case. To ensure the detection accuracy, it is necessary to calibrate the blood oxygen simulator to adapt to different blood oxygen meters. Summary of the Invention

[0004] The invention objective of this application is to solve the problems in the background art, and provide a calibration method and system for a blood oxygen simulator to adapt to different blood oxygen meters, so as to ensure the accuracy of using different blood oxygen meters to detect the blood oxygen saturation of the blood oxygen simulator set on a medical model.

[0005] This application is implemented through the following technical solutions:

[0006] A calibration method for a blood oxygen simulator to adapt to different blood oxygen meters includes the following steps:

[0007] S1. Obtain the blood oxygen detection parameter signal output by the blood oxygen meter, extract the first signal and the second signal based on the obtained blood oxygen detection parameter signal. The blood oxygen simulator outputs the third signal and the fourth signal according to the received first signal and second signal. Among them, the first signal is the timing signal of the blood oxygen meter emitting light, the second signal is the amplitude signal of the blood oxygen meter emitting light, that is, the signal of the change frequency of the light emission intensity of red light and infrared light. The third signal is the timing signal of the blood oxygen simulator emitting light, and the fourth signal is the signal of the change frequency of the light emission intensity of red light and infrared light of the blood oxygen simulator. Adjust the fourth signal by adjusting four driving voltages to synchronize it with the second signal;

[0008] S2. The blood oxygen meter obtains the third signal and the fourth signal output by the blood oxygen simulator to measure the blood oxygen saturation;

[0009] S3. Calibrate the blood oxygen saturation detected by the pulse oximeter. The specific calibration steps are as follows:

[0010] S31. Divide the blood oxygen saturation into multiple segment points and determine the corresponding relationship between the blood oxygen saturation of each segment point and the four driving voltage components. The steps include:

[0011] S311. Determine the relationship between the blood oxygen saturation and the four driving voltage components;

[0012] S312. Determine the driving voltage change component that is linearly related to the blood oxygen saturation between every two segment points;

[0013] S313. Adjust the values of the other three driving voltage components so that the four driving voltage components correspond to the blood oxygen saturation of the two segment points;

[0014] S32. Based on the corresponding relationship between the blood oxygen saturation of each segment point and the four driving voltage components in step S31, adjust the driving voltage change component of this segment point to calibrate the blood oxygen saturation detected by the pulse oximeter. The calibration formula is as (1):

[0015] (1)

[0016] Wherein, is the driving voltage value component corresponding to a blood oxygen saturation of 100; is the blood oxygen value of the calibration point, with a value range of 0-99, ; is the voltage value to be changed for each calibration point compared to the previous calibration point. The sum of the voltage values changed in each segment and the previous segment is the driving voltage value component of this calibration point;

[0017] If the blood oxygen saturation detected by the pulse oximeter is the same as the set value, the calibration of the blood oxygen simulator is completed; if not, adjust the magnitude of the driving voltage change component until the blood oxygen saturation detected by the pulse oximeter is the same as the set value.

[0018] Furthermore, the four driving voltage components include a red light DC driving voltage, a red light AC driving voltage, an infrared light DC driving voltage, and an infrared light AC driving voltage.

[0019] Furthermore, the specific steps to adjust the fourth signal to be synchronized with the second signal are as follows: that is, adjust the change frequencies of the emission intensities of the red light and infrared light output by the blood oxygen simulator to be synchronized with the change frequencies of the emission intensities of the red light and infrared light in the detected pulse wave output by the pulse oximeter according to the heart rate;

[0020] S11. Obtain the number of times the red light AC driving voltage changes in one pulsation. The calculation formula is as (2):

[0021] (2)

[0022] Wherein, is the number of times of change of the red light AC driving voltage, is the time interval between two heartbeats, is the set red light change interval;

[0023] Obtain the number of times of change of the infrared light AC driving voltage in one pulsation. The calculation formula is as in (3):

[0024] (3)

[0025] Wherein, is the number of times of change of the infrared light AC driving voltage, is the time interval between two heartbeats, is the set infrared light change interval;

[0026] S12. Obtain the number of times of rise and fall of the red light AC driving voltage in one pulsation. The number of times of rise and fall of this red light AC driving voltage is the number of times of change of the red light intensity in one pulsation. The calculation formulas are as in (4) and (5):

[0027] (4)

[0028] (5)

[0029] Wherein, is the number of times of rise of the red light AC driving voltage, is the number of times of fall of the red light AC driving voltage, is the time ratio of the rising section of the red light AC driving voltage, is the time ratio of the falling section of the red light AC driving voltage;

[0030] Obtain the number of times of rise and fall of the infrared light AC driving voltage in one pulsation. The number of times of rise and fall of this infrared light AC driving voltage is the number of times of change of the infrared light intensity in one pulsation. The calculation formulas are as in (6) and (7):

[0031] (6)

[0032] (7)

[0033] Wherein, is the number of times of rise of the infrared light AC driving voltage, is the number of times of fall of the infrared light AC driving voltage, is the time ratio of the rising section of the infrared light AC driving voltage, is the time ratio of the falling section of the infrared light AC driving voltage;

[0034] Among them, the number of times the red light AC drive voltage rises and the number of times the red light AC drive voltage drops are the change frequencies of the red light intensity; the number of times the infrared light AC drive voltage rises and the number of times the infrared light AC drive voltage drops are the change frequencies of the infrared light intensity.

[0035] S13. By adjusting the ratio of the red light AC drive voltage rise time and fall time and the infrared light AC drive voltage rise time and fall time until a stable pulse wave waveform appears on the oximeter, it can be determined that the fourth signal is synchronized with the second signal.

[0036] Further, in one pulsation, the time ratio of the rising section of the red light AC drive voltage is set to 15% - 30%, and the time ratio of the falling section of the red light AC drive voltage is set to 70% - 85%; the time ratio of the rising section of the infrared light AC drive voltage is set to 70% - 85%, and the time ratio of the falling section of the infrared light AC drive voltage is set to 15% - 30%.

[0037] Further, the linear relationship between the blood oxygen saturation at each two segmentation points and the change voltage component can be a direct proportional relationship or an inverse proportional relationship.

[0038] Further, step S312 specifically includes the following steps:

[0039] S3121. Determine the primary change ranges of the red light DC drive voltage and the infrared light DC drive voltage;

[0040] S3122. Determine the primary change ranges of the red light AC drive voltage and the infrared light AC drive voltage;

[0041] S3123. Further determine the secondary voltage change ranges of the four drive voltages based on the primary change ranges of the red light DC drive voltage, the infrared light DC drive primary change range, the red light AC drive voltage primary change range, and the infrared light AC drive voltage primary change range determined in steps S3121 - S3122;

[0042] S3124. Keep the midpoint values of the secondary voltage change ranges of any three drive voltage components unchanged, adjust within the secondary voltage change range of the remaining one drive voltage, and determine whether it can control a large change in blood oxygen saturation. If so, it can be determined that this drive voltage component is the change voltage component linearly related to the blood oxygen saturation at this segmentation point. If not, re - select the changing drive voltage component and determine whether it can control a large change in blood oxygen saturation.

[0043] Further, step S3121 specifically includes the following steps:

[0044] S31211. Set the initial values of the red light AC driving voltage and the infrared light AC driving voltage to any integer value within 50 - 100 mV, and set the initial values of the red light DC driving voltage and the infrared light DC driving voltage to 0 mV;

[0045] S31212. Increase the red light DC driving voltage and the infrared light DC driving voltage step by step at a step size of 50 mV or 100 mV within the range of 0 mV - 3200 mV respectively, and obtain the first voltage range and the second voltage range where waveforms appear on the pulse oximeter. Among them, the first voltage range is the primary change range of the red light DC driving voltage, and the second voltage range is the primary change range of the infrared light DC driving voltage.

[0046] Further, the specific method of step S3122 is: Take the midpoint values of the primary voltage ranges of the red light DC driving voltage and the infrared light DC driving voltage determined in step S3121 as the red light DC driving voltage and the infrared light DC driving voltage respectively, set the value of the infrared light AC driving voltage to a fixed value, increase the value of the red light AC driving voltage from 0 mV step by step at a step size of 10 mV, and record the voltage range where waveforms appear on the pulse oximeter, which is the primary voltage change range of the red light AC driving voltage. In this way, the primary change range of the infrared light AC driving voltage can be obtained.

[0047] Further, the specific method of step S3123 is:

[0048] Based on the primary voltage change ranges of the four driving voltages determined in steps S3121 - 3122, set any three driving voltages to the midpoint values of their primary voltage change ranges, adjust the remaining one driving voltage within its primary voltage change range, and successively determine the voltage ranges where the adjacent blood oxygen saturations within the range of 0 - 99 have the same linear relationship with it. Then this voltage change range is the secondary voltage change range, and the blood oxygen saturations corresponding to the two endpoints of this secondary voltage change range are the blood oxygen saturations at the two endpoints of the segment.

[0049] A system for a blood oxygen simulator to adapt to different pulse oximeters, including a blood oxygen simulator, a pulse oximeter, and a computer, where:

[0050] The blood oxygen simulator includes a simulated finger and a control module. A blood oxygen simulation circuit board is arranged inside the simulated finger, and a photosensitive triode and a lamp bead are arranged on the blood oxygen simulation circuit board. A light signal receiving circuit, a DAC voltage regulating circuit, a switch control circuit, and a processor lamp bead are arranged on the control module;

[0051] The described photosensitive triode receives the blood oxygen detection parameter signal emitted by the blood oxygen meter, converts this signal into an electrical signal and transmits it to the optical signal receiving circuit. The electrical signal is processed and adjusted in the optical signal receiving circuit to form a first signal and a second signal, which are sent to the control module. After receiving the signals, the control module issues an instruction to the DAC voltage regulation circuit. The DAC voltage regulation circuit sends a signal to the switch control circuit, and according to the instructions of the first signal and the second signal, it starts the lamp beads to emit light and outputs a third signal and a fourth signal;

[0052] The blood oxygen meter receives the third signal and the fourth signal to detect the simulated blood oxygen saturation;

[0053] The computer is connected to the blood oxygen simulator in a wired or wireless manner. A calibration formula and a data storage module are set in the computer. The calibration formula is used to calibrate the blood oxygen saturation detected by the blood oxygen meter, and the data storage module is used to store the calibration formula and calibration data.

[0054] Furthermore, the photosensitive triode includes a red light photosensitive triode and an infrared light photosensitive triode, and the lamp beads include red light lamp beads and infrared light lamp beads.

[0055] Furthermore, two N-MOS transistors are arranged on the optical signal receiving circuit. The first N-MOS transistor is used to perform voltage waveform stabilization processing on the received signal and convert it into a pure high and low level. Then, the second N-MOS transistor performs an inverting process on the converted pure level to ensure that the output signal is in phase with the received signal.

[0056] Furthermore, a voltage follower is arranged on the DAC voltage regulation circuit to improve the driving ability of the output voltage optical signal. The DAC voltage regulation circuit can output four driving voltage components, including a red light DC driving voltage, a red light AC driving voltage, an infrared light DC driving voltage, and an infrared light AC driving voltage, which are used to adjust and control the light emission intensity and frequency of the red light lamp beads and the infrared light lamp beads.

[0057] Furthermore, a transparent window is arranged at the front end of the simulated finger to receive the red light and infrared light emitted by the blood oxygen meter, and a transparent window is arranged at the rear end of the simulated finger to transmit the light waves emitted by the red light lamp beads and the infrared light lamp beads to the blood oxygen meter.

[0058] The beneficial effects of this application are:

[0059] This application calibrates the blood oxygen simulator by adjusting the simulated optical signal output on the blood oxygen simulator to synchronize with the optical signal output by the blood oxygen meter and calibrating the blood oxygen saturation detected by the blood oxygen meter, so that it is applicable to blood oxygen simulators of different manufacturers and different models for detecting simulated blood oxygen saturation; linear calibration is performed using the proportional relationship between the blood oxygen saturation at each segmentation point and the driving voltage component. During the calibration process, only the driving voltage change component linearly related to each segmentation point needs to be adjusted to adjust the simulated optical signal output by the blood oxygen simulator, so that the blood oxygen saturation detected by the blood oxygen meter is the same as the value set by the computer. This calibration method is simple and easy to operate and is not limited by the blood oxygen curve. Description of the Drawings

[0060] Figure 1 It is a schematic flowchart of the calibration method of this application;

[0061] Figure 2 It is a schematic flowchart for adjusting the fourth signal to synchronize with the second signal;

[0062] Figure 3 It is a schematic flowchart of the blood oxygen saturation calibration steps;

[0063] Figure 4 It is a schematic flowchart for determining the corresponding relationship between the blood oxygen saturation at the segmentation points and the four driving voltages;

[0064] Figure 5 It is a schematic flowchart for determining the driving voltage change component linearly related to the blood oxygen saturation at each segmentation point;

[0065] Figure 6 It is a schematic flowchart for determining the primary change range of the driving voltages of red light and infrared light;

[0066] Figure 7 It is a calibration display interface diagram;

[0067] Figure 8 It is a schematic structural diagram of this calibration device;

[0068] Figure 9 It is a circuit diagram of the optical signal receiver;

[0069] Figure 10 It is a circuit diagram of the DAC voltage regulation;

[0070] Figure 11 It is a circuit diagram of the switch control. Detailed Description of the Preferred Embodiment

[0071] To more clearly illustrate the relationship between the technical problems, technical solutions, and technical effects to be achieved in this application, the following detailed description is given in combination with specific embodiments.

[0072] In this embodiment, in combination withFigures 1 to 4 As shown in Figures 1 to 4 , a calibration method for a blood oxygen simulator to adapt to different blood oxygen meters is based on a blood oxygen meter and a blood oxygen simulator. The blood oxygen meter is a real blood oxygen meter of any manufacturer and any model purchased on the market. The specific calibration steps are as follows:

[0073] S1. Obtain the blood oxygen detection parameter signal output by the blood oxygen meter, extract the first signal and the second signal based on the obtained blood oxygen detection parameter signal, and the blood oxygen simulator outputs the third signal and the fourth signal according to the received first signal and second signal. Among them, the first signal is the timing signal of the blood oxygen meter emitting light, the second signal is the amplitude signal, that is, the signal of the changing frequency of the light emission intensity of red light and infrared light in the pulse wave received when the blood oxygen meter is actually used. The third signal is the timing signal of the blood oxygen simulator emitting light, and the fourth signal is the signal of the light emission intensity frequency of red light and infrared light of the blood oxygen simulator. Adjust the fourth signal by adjusting four driving voltages to synchronize with the second signal;

[0074] The signal of the light emission intensity frequency of red light and infrared light is the light signal that shows a periodic change of strong and weak pulse when the light emitted by the blood oxygen meter is absorbed by the measured finger during the actual measurement of blood oxygen saturation of a real person by the blood oxygen meter. It is composed of the waveforms of two components, red light and infrared light. Both waveforms are composed of a constant DC component and an AC component that changes with the pulse, that is, the DC component of red light, the AC component of red light, the DC component of infrared light, and the AC component of infrared light. Since the DC components of red light and infrared light are constants, the change of the AC component will cause the change of light intensity. Therefore, in this embodiment, the output magnitudes of the red light driving voltage and the infrared light driving voltage in the blood oxygen simulator are changed with the heart rate to simulate the continuous AC component in the waveform. The specific steps are as follows:

[0075] S11. Obtain the number of times the red light AC driving voltage changes during one pulsation. The calculation formula is as (2):

[0076] (2)

[0077] Among them, is the number of times the red light AC driving voltage changes, is the time interval between two heartbeats, is the set red light change interval;

[0078] Obtain the number of times the infrared light AC driving voltage changes during one pulsation. The calculation formula is as (3):

[0079] (3)

[0080] Among them, is the number of times the infrared light AC driving voltage changes, is the time interval between two heartbeats, is the set infrared light change interval;

[0081] In this embodiment, the number of times the red light AC drive voltage changes is the same as the number of times the infrared light AC drive voltage changes, where is the time interval between two heartbeats, that is, the heart rate is the reciprocal of = 60000 / , in this embodiment, the red light and infrared light change intervals are set to 1 ms, so the number of times the red light AC drive voltage and the infrared light AC drive voltage change are calculated by formula (3-1):

[0082] (3-1)

[0083] After determining the number of times the red light AC drive voltage and the infrared light AC drive voltage change in one pulsation, it is necessary to determine the number of times the red light and infrared light AC drive voltages rise and fall in one pulsation. The number of times the red light and infrared light AC drive voltages rise is fitted into the rising section from the trough to the peak, and the number of times the red light and infrared light AC drive voltages fall is fitted into the falling section from the peak to the trough. Another purpose of determining the number of times the red light and infrared light AC drive voltages rise and fall here is to determine the waveform that can be detected by the pulse oximeter and ensure the smoothness of the waveform, so as to ensure the accuracy of the pulse oximeter in detecting the simulated blood oxygen saturation. The specific calculation formulas are as (4), (5),

[0084] (4)

[0085] (5)

[0086] Where is the number of times the red light AC drive voltage rises, is the number of times the red light AC drive voltage falls, is the time ratio of the rising section of the red light AC drive voltage, is the time ratio of the falling section of the red light AC drive voltage;

[0087] Obtain the number of times the infrared light AC drive voltage rises and falls in one pulsation. The number of times the infrared light AC drive voltage rises and falls is the number of times the infrared light intensity changes in one pulsation. The calculation formulas are as (6), (7):

[0088] (6)

[0089] (7)

[0090] Where is the number of times the infrared light AC drive voltage rises, is the number of times the AC drive voltage of the infrared light drops is the proportion of the rising time of the AC drive voltage of the infrared light, is the proportion of the falling time of the AC drive voltage of the infrared light;

[0091] Among them, the number of times the red light AC drive voltage rises and the number of times the red light AC drive voltage drops are the change frequencies of the red light intensity; the number of times the infrared light AC drive voltage rises and the number of times the infrared light AC drive voltage drops are the change frequencies of the infrared light intensity;

[0092] In this embodiment, the proportion of the rising time of the red light AC drive voltage is set to 20%, the proportion of the falling time is set to 80%, the proportion of the rising time of the infrared light AC drive voltage is set to 80%, and the proportion of the falling time is set to 20%. In some other embodiments, the proportion of the rising time of the red light AC drive voltage can be set to 15%, the proportion of the falling time can be set to 85%, the proportion of the rising time of the infrared light AC drive voltage can be set to 85%, and the proportion of the falling time can be set to 15%. By adjusting the proportion of the rising and falling times of the red light and infrared light AC drive voltages, the change frequencies of the red light and infrared light emission intensities are adjusted to adapt to different models of pulse oximeters from different manufacturers.

[0093] S13. Adjust the rising time and falling time of the red light AC drive voltage, and the ratio of the rising time and falling time of the infrared light AC drive voltage until a stable pulse wave waveform appears on the pulse oximeter, then it can be determined that the fourth signal is synchronized with the second signal.

[0094] Proceed to step S2: The pulse oximeter obtains the third signal and the fourth signal output by the blood oxygen simulator for the determination of blood oxygen saturation.

[0095] Calibrate the blood oxygen saturation measured by the pulse oximeter in step S2 through step S3:

[0096] The specific steps are as follows:

[0097] S31. Divide the blood oxygen saturation into multiple segment points, and determine the corresponding relationship between the blood oxygen saturation of each segment point and the four drive voltage components. The steps include:

[0098] S311. Determine the relationship between the blood oxygen saturation and the four drive voltage components;

[0099] The pulse oximeter calculates the blood oxygen saturation according to the ratio of the four components in the pulse wave signal. In this application, the four drive voltages corresponding to the four components in the pulse wave signal are used for the determination of blood oxygen saturation. The four drive voltages are respectively the red light DC drive voltage, denoted as the red light AC drive voltage, denoted as the infrared light DC drive voltage, denoted as , the infrared light AC driving voltage, denoted as , so the blood oxygen saturation has the relationship formula (8) with the four driving voltage components as follows:

[0100] (8)

[0101] S312. Determine the driving voltage change components that are linearly related to the blood oxygen saturation at every two segmentation points, such as Figure 5 shown. The steps include:

[0102] S3121. Determine the primary change ranges of the red light DC driving voltage and the infrared light DC driving voltage, and set the driving voltage values of the red light DC driving voltage and the infrared light DC driving voltage as the midpoint values of their primary change ranges;

[0103] S3122. Determine the primary change ranges of the red light AC driving voltage and the infrared light AC driving voltage, and set the midpoint values of the primary change ranges of the red light AC driving voltage and the infrared light AC driving voltage as the values of the red light AC driving voltage and the infrared light AC driving voltage;

[0104] S3123. Further determine the secondary voltage change ranges of the four driving voltages based on the primary change ranges of the red light DC driving voltage, the infrared light DC driving primary change range, the red light AC driving voltage primary change range, and the infrared light AC driving voltage primary change range determined in steps S3121 - S3122;

[0105] S3124. Based on steps S3121 - S3123, according to formula (8), select the midpoint values of the secondary voltage change ranges of any three driving voltage components to remain unchanged, and adjust within the secondary voltage change range of the remaining one driving voltage. Determine whether it can control a large change in blood oxygen saturation. If so, determine this driving voltage component as the change voltage component that is linearly related to the blood oxygen saturation at this segmentation point. If not, re - select the three voltage components with unchanged driving voltage values, adjust the values of the re - selected driving voltage change component, and judge its relationship with the blood oxygen saturation at the two segmentation points. Multiple selections and adjustments can be made until the driving voltage change component that is linearly related to the blood oxygen saturation at the two segmentation points is determined.

[0106] S313. After step S312, within the secondary voltage change range, adjust the values of the other three driving voltages, so as to determine the corresponding relationship between the segmentation point blood oxygen saturation and the four driving voltage components.

[0107] Determine the corresponding relationships between the blood oxygen saturations at other segmentation points and the four driving voltage components in turn according to this method.

[0108] After determining the correspondence between the blood oxygen saturation and the four driving voltage components, it can be known that the blood oxygen saturation at the segmentation point and the driving voltage showing a linear relationship with it can be in a direct proportion relationship or an inverse proportion relationship.

[0109] As Figure 6 shown, the specific method for determining the primary change range of the red light DC driving voltage determined in step S3121 is as follows:

[0110] S31211. Set the initial values of both the red light AC driving voltage and the infrared light AC driving voltage to 50 mV, and set the value of the infrared light DC driving voltage to 0 mV;

[0111] S31212. Record the voltage range where waveforms appear on the pulse oximeter when the red light DC driving voltage ranges from 0 mV to 3200 mV. The adjustment of the red light DC driving voltage can be incremented in steps of 50 mV or 100 mV. After testing, during the process of increasing the red light DC driving voltage within the range of 0 mV to 3200 mV, the first voltage range where waveforms appear on the pulse oximeter is 1600 mV to 2200 mV. Then this first voltage range is the primary change range of the red light DC driving voltage.

[0112] Using this method, set the initial values of the red light AC driving voltage and the infrared light AC driving voltage to 50 mV, and set the value of the red light DC driving voltage to 0 mV. The obtained second voltage range is 1100 mV to 1500 mV, which is the primary change range of the infrared light DC driving voltage.

[0113] In this embodiment, the value of the red light DC driving voltage is the midpoint value of the primary change range, which can be 1800 mV, and the value of the infrared light DC driving voltage is also selected as the midpoint value of the primary change range, which can be 1300 mV.

[0114] The method for determining the primary change range of the red light and infrared light AC driving voltages in step S3122 is to set the values of the red light DC driving voltage and the infrared DC driving voltage to the midpoint values of the primary change ranges. Within the range of 0 mV to 1600 mV, increase the red light AC driving voltage from 0 mV in steps of 10 mV, and record the third voltage range where waveforms appear on the pulse oximeter, which is the primary change range of the red light AC driving voltage. After testing, it is 10 mV to 60 mV. After setting the red light AC driving voltage to the midpoint 35 mV of the primary change range, the obtained fourth voltage range using this method is the primary voltage change range of the infrared light, which is 5 mV to 50 mV, and its midpoint of the primary change range is 30 mV.

[0115] Further, the method for determining the secondary change ranges of the four driving voltage components in step S3123 is as follows: According to the relationship between blood oxygen saturation and the four driving voltage components, after setting any three driving voltage components to the midpoints of their primary voltage change ranges, adjust the remaining one driving voltage within its primary voltage change range, observe the values on the blood oxygen meter, and use the voltage range that has a linear relationship with the adjacent blood oxygen saturations as the secondary voltage change range of the adjacent blood oxygen saturations. This adjacent blood oxygen saturation is the blood oxygen saturation at both endpoints of the corresponding segment. According to this method, the secondary voltage change ranges of the other driving voltages corresponding to each segmentation point can be determined. In this embodiment, the segmented range of the blood oxygen saturation is set to 0-99.

[0116] After determining the secondary voltage change ranges of the red light DC driving voltage, infrared light DC driving voltage, red light AC driving voltage, and infrared light AC driving voltage, according to formula (8), any three driving voltages can be selected to keep their midpoint values in the interval unchanged, and the change value of the remaining one driving voltage is adjusted within the secondary voltage change range. The voltage component with a larger change in blood oxygen value is set as the voltage component used for calibration.

[0117] Based on the corresponding relationships between the blood oxygen saturations at each segmentation point and the four driving voltage components determined in the above steps, within the secondary change ranges of the four driving voltages, adjust the driving voltage change components to calibrate the blood oxygen saturation detected by the blood oxygen meter, and then enter step S32. The specific calibration formula is as follows (1):

[0118] (1)

[0119] Wherein, is the driving voltage value component corresponding to a blood oxygen saturation of 100; is the blood oxygen value at the calibration point, and the value range is 0-99, ; is the voltage value that needs to be changed for each calibration point compared to the previous calibration point. The sum of the voltage values changed in each segment and the previous segment is the driving voltage value component of this calibration point.

[0120] The specific adjustment and calibration method is as follows: Place the blood oxygen meter correctly on the simulated finger, turn on the computer, and display the calibration interface as Figure 7 shown:

[0121] Click on any calibration point , view the blood oxygen saturation obtained on the blood oxygen meter, and compare it with . If they are the same, complete the calibration of the point. If they are different, adjust according to the direct or inverse proportional relationship between the calibration point and the driving voltage change component. If it is a direct proportional relationship, when the blood oxygen saturation detected by the blood oxygen meter is higher than If the value is small, increase the value of the driving voltage change component until the blood oxygen saturation detected by the pulse oximeter is the same as the value. If it is inversely proportional, adjust the value of the driving voltage change component in the reverse direction.

[0122] After completing the calibration of one calibration point, perform the calibration of other calibration points in the same way. After completing the calibration of all calibration points, save the parameters to the computer to complete the calibration of the blood oxygen simulator, that is, complete the adaptation to the pulse oximeter.

[0123] As Figure 8 shown, a system for a blood oxygen simulator to adapt to different pulse oximeters can implement a calibration method for a blood oxygen simulator to adapt to different pulse oximeters. It includes a blood oxygen simulator, a pulse oximeter, and a computer, where:

[0124] The blood oxygen simulator includes a simulated finger and a control module. A blood oxygen simulation circuit board is arranged inside the simulated finger. A photosensitive triode, an optical signal receiving circuit, a DAC voltage regulating circuit, and a lamp bead are arranged on the blood oxygen simulation circuit board and are electrically connected. The photosensitive triode receives the blood oxygen parameter detection signal emitted by the pulse oximeter, and converts the blood oxygen detection signal into an electrical signal and transmits it to the optical signal receiving circuit. The electrical signal is processed and adjusted in the optical signal receiving circuit to form a first signal and a second signal, and is sent to the control module. After receiving the first signal and the second signal, the control module issues an instruction to the DAC voltage regulating circuit. The DAC voltage regulating circuit sends a signal to the signal terminal of the switch control circuit to jointly control the lamp bead to emit light, and obtain a third signal and a fourth signal. The pulse oximeter receives the third signal and the fourth signal to detect the blood oxygen saturation. The computer is connected to the blood oxygen simulator in a wired or wireless manner. A calibration formula and a data storage module are arranged in the computer. The calibration formula is used to calibrate the blood oxygen saturation detected by the pulse oximeter. If the blood oxygen saturation detected by the pulse oximeter is the same as the value set in the computer, no calibration is required. If not, according to the calibration formula, the control module adjusts the voltage value of the DAC voltage regulating circuit to drive the lamp bead to emit light, obtains the adjusted third signal and fourth signal, and re-detects the blood oxygen saturation. The data storage module is used to store the calibration formula and the calibrated data.

[0125] Specifically, the first signal is the timing signal of the light emission of the oximeter, the second signal is the amplitude signal of the oximeter, i.e., the light emission intensity and frequency signals of red light and infrared light, the third signal is the timing signal of the light emission of the blood oxygen simulator, and the fourth signal is the light emission intensity and frequency signals of red light and infrared light of the blood oxygen simulator; the photosensitive triode includes a red-light photosensitive triode and an infrared-light photosensitive triode, and the lamp beads include red-light lamp beads and infrared-light lamp beads; the DAC voltage regulating circuit is used to adjust the light emission intensity and change frequency of the red-light lamp beads and infrared-light lamp beads to achieve the calibration of the blood oxygen simulator and make it compatible with the oximeter.

[0126] Specifically, the optical signal receiving circuit receives the signals transmitted by the photosensitive triodes. The photosensitive triodes are divided into a red-light photosensitive triode and an infrared-light photosensitive triode, which respectively receive red-light signals and infrared-light signals and process the received red-light signals and infrared-light signals. As Figure 9 shown, two N-MOS transistors are provided in the optical signal receiving circuit. The first N-MOS transistor is used to perform voltage waveform stabilization processing on the received red-light signal and / or red-light signal and convert it into pure high and low levels. Then, after the second N-MOS transistor performs an inversion process on the received signal, the first signal and the second signal are obtained, which are used as the signal instruction basis for the control module to control the DAC voltage regulating circuit to drive the lamp beads to emit light, so as to obtain the third signal and the fourth signal.

[0127] As Figure 10 shown, a voltage follower is provided on the DAC voltage regulating circuit to improve the driving ability of the output voltage optical signal. The two-way driving voltages that the DAC voltage regulating circuit can output include four driving voltage components, including red-light DC driving voltage, red-light AC driving voltage, infrared-light DC driving voltage, and infrared-light AC driving voltage, which are used to adjust and control the light emission intensity and frequency of the red-light lamp beads and infrared-light lamp beads. After receiving the signal from the processor control module, the DAC voltage regulating circuit sends a signal to the switch control circuit. As Figure 11 shown, the common terminal COM of the switch control circuit is connected to the lamp beads, the normally closed terminal NC is connected to the power supply voltage to keep the lamp beads in an off state, the normally open terminal NO is connected to the output of the DAC voltage regulating circuit, and the control terminal IN is connected to the output of the optical signal receiving circuit to control the conduction between the common terminal and the normally open terminal. In this system, the light emission of the lamp beads is controlled by applying an analog switch to form a switch control circuit, which shortens the response time of the system.

[0128] A transparent window is provided at the front end of the simulated finger to receive the red light and infrared light emitted by the oximeter, and a transparent window is provided at the rear end of the simulated finger to transmit the light waves emitted by the red-light lamp beads and infrared-light lamp beads to the oximeter.

Claims

1. A calibration method for a blood oxygen simulator to adapt to different blood oxygen meters, characterized in that, It includes the following steps: S1. Obtain the blood oxygen detection parameter signal output by the pulse oximeter, extract the first signal and the second signal based on the obtained blood oxygen detection parameter signal. The blood oxygen simulator outputs the third signal and the fourth signal according to the received first signal and second signal. Wherein, the first signal is the timing signal of the light emission of the pulse oximeter, the second signal is the amplitude signal of the light emission of the pulse oximeter, that is, the light emission intensity and frequency signal of red light and infrared light, the third signal is the timing signal of the light emission of the blood oxygen simulator, and the fourth signal is the light emission intensity and frequency signal of red light and infrared light of the blood oxygen simulator. The fourth signal synchronizes the second signal by adjusting four driving voltages; S2. The pulse oximeter obtains the third signal and the fourth signal output by the blood oxygen simulator to measure the blood oxygen saturation; S3. Calibrate the blood oxygen saturation detected by the pulse oximeter. The specific calibration steps are as follows: S31. Divide the blood oxygen saturation into multiple segment points, and determine the corresponding relationship between the blood oxygen saturation of each segment point and the four driving voltage components. The steps include: S311. Determine the relationship between the blood oxygen saturation and the four driving voltage components; S312. Determine the driving voltage change component that is linearly related to the blood oxygen saturation between every two segment points. The specific steps include: S3121. Determine the primary change range of the red light DC driving voltage and the infrared light DC driving voltage; S3122. Determine the primary voltage range of the red light AC driving voltage and the infrared light AC driving voltage; S3123. Further determine the secondary voltage change range of the four driving voltages at each segment point according to the primary change range of the red light DC driving voltage, the primary change range of the infrared light DC driving voltage, the primary change range of the red light AC driving voltage, and the primary change range of the infrared light AC driving voltage determined in steps S3121 - S3122; S3124. Keep the midpoint value of the secondary voltage change range of any three driving voltage components unchanged, and adjust within the secondary voltage change range of the remaining one driving voltage to determine whether it can control a large change in blood oxygen saturation. If so, it can be determined that this driving voltage component is the change voltage component linearly related to the blood oxygen saturation at this segment point. If not, re - select the changing driving voltage component and determine whether it can control a large change in blood oxygen saturation; S313. Within the secondary voltage change range, adjust the values of the remaining three driving voltage components so that the four driving voltage components correspond to the blood oxygen saturation of the two segment points; S32. Based on the corresponding relationship between the blood oxygen saturation of each segment point and the four driving voltage components in step S31, within the secondary voltage change range, adjust the driving voltage change component linearly related to this segment point to calibrate the blood oxygen saturation detected by the pulse oximeter. The calibration formula is as (1): （1） Among them, is the component of the drive voltage value corresponding to a blood oxygen saturation of 100; is the blood oxygen value at the calibration point, with a value range of 0 to 99, ; is the voltage value that needs to be changed for each calibration point compared to the previous calibration point. The sum of the voltage values changed in each segment and the previous segment is the component of the drive voltage value at this calibration point; If the blood oxygen saturation detected by the pulse oximeter is consistent with the set value, the calibration of the blood oxygen simulator is completed; if not, adjust the magnitude of the driving voltage change component until the blood oxygen saturation detected by the pulse oximeter is consistent with the set value.

2. The calibration method for a blood oxygen simulator to adapt to different blood oxygen meters according to claim 1, wherein, The four driving voltage components described above include a red light DC driving voltage, a red light AC driving voltage, an infrared light DC driving voltage, and an infrared light AC driving voltage.

3. A calibration method for a blood oxygen simulator to adapt to different blood oxygen meters according to claim 1, characterized in that The specific steps for adjusting the fourth signal to be synchronous with the second signal are as follows: S11. Obtain the number of times the red light AC driving voltage changes in one pulse. The calculation formula is as shown in (2): （2） Among them, is the number of times the red light AC driving voltage changes, is the time interval between two heartbeats, is the set red light change interval; Obtain the number of times the infrared light AC driving voltage changes in one pulse. The calculation formula is as shown in (3): （3） Among them, is the number of times of the AC driving voltage change of the infrared light, is the time interval between two heartbeats, is the set infrared light change interval; S12. Obtain the number of times the red light AC driving voltage rises and falls in one pulse. The number of times the red light AC driving voltage rises and falls is the number of times the red light intensity changes in one pulse. The calculation formulas are as shown in (4) and (5): （4） （5） Among them, is the number of times the red light AC driving voltage rises, is the number of times the red light AC driving voltage drops, is the time ratio of the rising section of the red light AC driving voltage, is the time ratio of the falling section of the red light AC driving voltage; Obtain the number of times the infrared light AC driving voltage rises and falls in one pulse. The number of times the infrared light AC driving voltage rises and falls is the number of times the infrared light intensity changes in one pulse. The calculation formulas are as shown in (6) and (7): （6） （7） Wherein, is the number of times the AC driving voltage of the infrared light rises, is the number of times the AC driving voltage of the infrared light drops, is the time ratio of the rising section of the AC driving voltage of the infrared light, is the time ratio of the dropping section of the AC driving voltage of the infrared light; Among them, the number of times the red light AC driving voltage rises and the number of times the red light AC driving voltage falls are the red light intensity change frequencies; the number of times the infrared light AC driving voltage rises and the number of times the infrared light AC driving voltage falls are the infrared light intensity change frequencies; S13. Adjust the ratio of the rising time and falling time of the red light AC driving voltage and the rising time and falling time of the infrared light AC driving voltage until a stable pulse wave waveform appears on the pulse oximeter, and then it can be determined that the fourth signal is synchronous with the second signal.

4. A calibration method for a blood oxygen simulator to adapt to different blood oxygen meters according to claim 3, characterized in that, In one pulse, the time ratio of the rising section of the red light AC driving voltage is set to 15% - 30%, and the time ratio of the falling section of the red light AC driving voltage is set to 70% - 85%; the time ratio of the rising section of the infrared light AC driving voltage is set to 70% - 85%, and the time ratio of the falling section of the infrared light AC driving voltage is set to 15% - 30%.

5. A calibration method for a blood oxygen simulator to adapt to different blood oxygen meters according to claim 1, characterized in that, Step S3121 specifically includes the following steps: S31211. Set the initial values of the red light AC driving voltage and the infrared light AC driving voltage to any integer value within 50 - 100 mV, and set the initial values of the red light DC driving voltage and the infrared light DC driving voltage to 0 mV; S31212. Respectively increment the red light DC driving voltage and the infrared light DC driving voltage within the change range of 0 mV - 3200 mV with a step size of 50 mV or 100 mV, and respectively obtain the first voltage range and the second voltage range where waveforms appear on the pulse oximeter. Among them, the first voltage range is the primary change range of the red light DC driving voltage, and the second voltage range is the primary change range of the infrared light DC driving voltage.

6. The calibration method for a blood oxygen simulator to adapt to different blood oxygen meters according to claim 1, characterized in that, Step S3122 specifically includes the following steps: Respectively take the midpoint values of the primary voltage ranges of the red light DC driving voltage and the infrared light DC driving voltage determined in step S3121 as the red light DC driving voltage and the infrared light DC driving voltage, set the value of the infrared light AC driving voltage to a fixed value, increment the value of the red light AC driving voltage from 0 mV with a step size of 10 mV, and record the voltage range where waveforms appear on the pulse oximeter, which is the primary voltage change range of the red light AC driving voltage. In this way, the primary change range of the infrared light AC driving voltage can be obtained.

7. A calibration method for a blood oxygen simulator to adapt to different blood oxygen meters according to claim 1, characterized in that, The specific method of step S3123 is as follows: Set any three driving voltage components to the midpoint values within their primary voltage change ranges, and adjust the remaining one driving voltage within its primary voltage change range. Then, successively determine the voltage ranges corresponding to adjacent blood oxygen saturations within the range of 0 to 99 that have the same linear relationship with it. This voltage change range is the secondary voltage change range, and at the same time, the segmentation points of blood oxygen saturation are determined.

8. A calibration system for a blood oxygen simulator to adapt to different blood oxygen meters, which is used to implement the calibration method described in any one of claims 1 to 7, and is characterized in that, It includes a blood oxygen simulator, a blood oxygen meter, and a computer, where: The blood oxygen simulator includes an analog finger and a control module. Inside the analog finger, there is a blood oxygen simulation circuit board. On the blood oxygen simulation circuit board, there are a photosensitive triode, an optical signal receiving circuit, a DAC voltage regulating circuit, and a lamp bead. The photosensitive triode receives the optical signal emitted by the blood oxygen meter and converts the optical signal into an electrical signal, which is transmitted to the optical signal receiving circuit. The electrical signal is processed and adjusted in the optical signal receiving circuit to form a first signal and a second signal, which are sent to the control module. After receiving the signals, the control module issues an instruction to the DAC voltage regulating circuit. The DAC voltage regulating circuit sends a signal to the switch control circuit, and according to the instructions of the first signal and the second signal, it starts the lamp bead to emit light and output a third signal and a fourth signal. The blood oxygen meter receives the third signal and the fourth signal to detect the simulated blood oxygen saturation. The computer is connected to the blood oxygen simulator either wired or wirelessly. Inside the computer, there is a calibration formula and a data storage module. The calibration formula is used to calibrate the blood oxygen saturation detected by the blood oxygen meter, and the data storage module is used to store the calibration formula and calibration data.

9. The calibration system for a blood oxygen simulator adapted to different blood oxygen meters according to claim 8, characterized in that, The photosensitive triode includes a red light photosensitive triode and an infrared light photosensitive triode, and the lamp bead includes a red light lamp bead and an infrared light lamp bead.

10. A calibration system for a blood oxygen simulator to adapt to different blood oxygen meters according to claim 8, characterized in that, There are two N-MOS transistors on the optical signal receiving circuit. The first N-MOS transistor is used to stabilize the voltage waveform of the received signal and convert it into a pure level, and then the second N-MOS transistor performs an inverting process on the converted pure level to ensure that the output signal is in phase with the received signal.

11. A calibration system for a blood oxygen simulator adapted to different blood oxygen meters according to claim 8, characterized in that, There is a voltage follower on the DAC voltage regulating circuit to enhance the driving force of the output optical signal. The DAC voltage regulating circuit can output four driving voltage components, including a red light DC driving voltage, a red light AC driving voltage, an infrared light DC driving voltage, and an infrared light AC driving voltage.

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