Calibration circuit and method of continuous glucometer

Abstract

The invention relates to the technical field of glucometer calibration, and particularly discloses a calibration circuit and method for a continuous glucometer, and the calibration circuit comprises a control unit which is electrically connected with a counter electrode and a reference electrode of an electrochemical sensor; the acquisition unit comprises a transconductance operational amplifier and an analog-to-digital converter, the inverted input end of the transconductance operational amplifier is electrically connected with the working electrode of the electrochemical sensor, the in-phase input end of the transconductance operational amplifier is electrically connected with the reference level, and the output end of the transconductance operational amplifier is electrically connected with the input end of the analog-to-digital converter; the calibration unit comprises a resistor, a capacitor and an analog switch, the capacitor is connected with the analog switch in series and then connected with the resistor in parallel to form a resistance-capacitance network, and the resistance-capacitance network is bridged between the inverted input end and the output end of the transconductance operational amplifier; and the MCU is electrically connected with the control unit, the output end of the analog-to-digital converter and the control end of the analog switch. According to the invention, the MCU is used for controlling the analog switch to realize the connection or disconnection of the capacitor and the connection of the resistor, so that the rapid calibration in the production process can be realized, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of blood glucose meter calibration, and in particular to a calibration circuit and method for a continuous blood glucose meter. Background Art

[0002] Current continuous blood glucose meter products can monitor the patient's blood glucose level in real time. They are easy to wear and widely accepted by patients. The industry predicts that the market demand will grow by 30% annually by 2030. In order to improve the accuracy and stability of current continuous blood glucose meters during use, the speed of system analog signal acquisition is set very low. Therefore, the time required for the calibration of continuous blood glucose meters during production is also limited and cannot be accelerated. This mainly limits the output efficiency of such products and also affects the cost of the products.

[0003] When patients use continuous blood glucose meters, there may be various external interference sources, and these interference signals are easily coupled to the input signal of the sensor. The interference signal may be power frequency interference or other alternating signals. The blood glucose concentration signal sensed by the continuous blood glucose meter is a very slowly changing signal, such as tens of seconds or minutes. Generally, a low-pass filter with a very low cutoff frequency can be used to filter out the interference signal. The cutoff frequency of the low-pass filter is generally set to less than 1Hz. The blood glucose meter needs to perform a calibration process during the production process to calibrate the zero-point error and gain error introduced by the circuit in the system to improve accuracy. Considering the system accuracy requirements, the calibration process will take several seconds or even more than ten seconds. This will greatly reduce production efficiency.

[0004] Based on this technical background, the present invention studies a calibration circuit and method for a continuous blood glucose meter. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention proposes a calibration circuit and method for a continuous blood glucose meter. The calibration circuit forms a resistor-capacitor network by connecting a capacitor in series with an analog switch and then connecting the capacitor in parallel with a resistor. The resistor-capacitor network is bridged between the inverting input and output terminals of a transconductance amplifier. The analog switch is controlled by an MCU to connect or disconnect the capacitor from the resistor, thereby achieving rapid calibration during the production process. While improving production efficiency and measurement accuracy, the high reliability of the continuous blood glucose meter during use by patients can be maintained.

[0006] In order to achieve the above-mentioned object, the present invention provides, in a first aspect, a calibration circuit for a continuous blood glucose meter, a control unit, which is electrically connected to a counter electrode and a reference electrode of an electrochemical sensor; The acquisition unit includes a transconductance amplifier and an analog-to-digital converter, wherein the inverting input terminal of the transconductance amplifier is electrically connected to the working electrode of the electrochemical sensor, the non-inverting input terminal is electrically connected to the reference level, and the output terminal is electrically connected to the input terminal of the analog-to-digital converter; A calibration unit, comprising a resistor, a capacitor and one or two analog switches, wherein one end of the resistor is electrically connected to the inverting input end of the transconductance amplifier, and the other end is electrically connected to the output end of the transconductance amplifier, the capacitor and one or two analog switches are connected in series to form a capacitor switch branch, and the capacitor switch branch is connected in parallel with the resistor; The MCU is electrically connected to the control unit, the output end of the analog-to-digital converter and the control end of the analog switch respectively.

[0007] A second aspect of the present invention provides a method for calibrating a continuous blood glucose meter in the above-mentioned calibration circuit, comprising: During the calibration process, the MCU sends a control instruction to control the analog switch to disconnect the resistor and the capacitor, so as to calibrate the zero point and gain of the continuous blood glucose meter; After the calibration is completed, the MCU sends a control instruction to control the analog switch to close, the resistor and the capacitor are reconnected, the low-pass filter composed of the transconductance amplifier, the resistor and the capacitor starts to work, and the continuous blood glucose meter performs blood glucose detection.

[0008] The beneficial effects of the present invention include: The calibration circuit of the continuous blood glucose meter proposed in the present invention forms a resistor-capacitor network by connecting a capacitor in series with an analog switch and then connecting the capacitor in parallel with a resistor. The resistor-capacitor network is bridged between the inverting input terminal and the output terminal of a transconductance operational amplifier. The analog switch is controlled by an MCU to connect or disconnect the capacitor from the resistor, thereby realizing rapid calibration in the production process, improving production efficiency and measurement accuracy while still maintaining high reliability of the continuous blood glucose meter during patient use.

[0009] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0011] Figure 1 It is a structural schematic diagram of a specific implementation of the calibration circuit of the continuous blood glucose meter proposed by the present invention.

[0012] Figure 2 This is a schematic structural diagram of another specific implementation of the calibration circuit of the continuous blood glucose meter proposed by the present invention.

[0013] Figure 3 This is a schematic structural diagram of a third specific implementation manner of the calibration circuit of the continuous blood glucose meter proposed by the present invention.

[0014] Figure 4 This is a schematic diagram of the calibration test circuit structure of the third specific implementation mode of the calibration circuit of the continuous blood glucose meter proposed by the present invention.

[0015] Figure 5 This is a schematic diagram of a calibration test curve of a third specific implementation of the calibration circuit of the continuous blood glucose meter proposed by the present invention.

[0016] Figure 6 A schematic diagram of a calibration test curve of an existing calibration circuit.

[0017] Figure 7 The figure is a flow chart of a specific implementation of the method for calibrating a continuous blood glucose meter proposed in the present invention. DETAILED DESCRIPTION

[0018] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0019] In the present invention, unless otherwise specified, the directional words used, such as "upper and lower", generally refer to the upper and lower parts of the device in normal use, and "inside and outside" refer to the outline of the device. In addition, the terms "first, second, third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first, second, third" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0020] The present invention provides a calibration circuit for a continuous blood glucose meter, such as Figure 1 As shown, including: a control unit, electrically connected to a counter electrode and a reference electrode of the electrochemical sensor; The acquisition unit includes a transconductance amplifier and an analog-to-digital converter, wherein the inverting input terminal of the transconductance amplifier is electrically connected to the working electrode of the electrochemical sensor, the non-inverting input terminal is electrically connected to the reference level, and the output terminal is electrically connected to the input terminal of the analog-to-digital converter; The calibration unit includes a resistor, a capacitor and one or two analog switches, one end of the resistor is electrically connected to the inverting input terminal of the transconductance amplifier, and the other end is electrically connected to the output terminal of the transconductance amplifier, the capacitor and one or two analog switches are connected in series to form a capacitor switch branch, and the capacitor switch branch is connected in parallel with the resistor; The MCU is electrically connected to the control unit, the output end of the analog-to-digital converter and the control end of the analog switch respectively.

[0021] In the present invention, a capacitor is connected in series with an analog switch and then connected in parallel with a resistor to form a resistor-capacitor network, and the resistor-capacitor network is connected between the inverting input terminal and the output terminal of the transconductance amplifier. The analog switch is controlled by an MCU to connect or disconnect the capacitor from the resistor, thereby achieving rapid calibration in the production process, improving production efficiency and measurement accuracy while still maintaining high reliability of the continuous blood glucose meter during patient use.

[0022] According to the present invention, the capacitor switch branch is formed by connecting the analog switch and the capacitor in series, or, It is formed by connecting capacitors and analog switches in series, or The analog switch, the capacitor and the analog switch are connected in series in sequence.

[0023] According to the present invention, it also includes: A voltage reference is electrically connected to the reference input terminals of the digital-to-analog converter and the analog-to-digital converter, respectively, and is used to provide a reference operating voltage for the digital-to-analog converter and the analog-to-digital converter; The control unit includes: A digital-to-analog converter, the input end of which is electrically connected to the MCU; The operational amplifier has a non-inverting input terminal electrically connected to the output terminal of the digital-to-analog converter, an inverting output terminal electrically connected to the reference electrode, and an output terminal electrically connected to the counter electrode.

[0024] According to the present invention, during the calibration process, the calibration circuit sends a control instruction through the MCU to control the analog switch to disconnect the connection between the resistor and the capacitor, and then calibrates the zero point and gain of the continuous blood glucose meter. After the calibration is completed, the MCU sends a control instruction to control the analog switch to close, the resistor and the capacitor are reconnected, and the low-pass filter composed of the transconductance operational amplifier, the resistor and the capacitor starts to work, and the continuous blood glucose meter performs blood glucose detection.

[0025] According to the present invention, if an abnormality occurs in the calibration circuit during the calibration process, the abnormality processing is performed, and after the abnormality processing is completed, the calibration is restarted.

[0026] The present invention also provides a calibration method for a continuous blood glucose meter performed in the above calibration circuit, comprising: During the calibration process, the MCU sends a control instruction to control the analog switch to disconnect the resistor and capacitor, so as to calibrate the zero point and gain of the continuous blood glucose meter; When the calibration is completed, the MCU sends a control instruction to control the analog switch to close, the resistor and capacitor are reconnected, and the low-pass filter composed of the transconductance amplifier, resistor and capacitor starts working, and the continuous blood glucose meter performs blood glucose testing.

[0027] According to the present invention, it also includes: If an exception occurs during the calibration process, execute exception handling, and restart the calibration after the exception handling is completed.

[0028] According to the present invention, during the calibration and blood glucose testing of the continuous blood glucose meter, the MCU sends control instructions to the digital-to-analog converter, receives data collected by the analog-to-digital converter and performs relevant calculations.

[0029] The present invention will be described in more detail below through specific embodiments. Example

[0030] like Figure 1 As shown, this embodiment provides a calibration circuit for a continuous blood glucose meter, including: a control unit, electrically connected to a counter electrode and a reference electrode of the electrochemical sensor; The acquisition unit includes a transconductance amplifier and an analog-to-digital converter, wherein the inverting input terminal of the transconductance amplifier is electrically connected to the working electrode of the electrochemical sensor, the non-inverting input terminal is electrically connected to the reference level, and the output terminal is electrically connected to the input terminal of the analog-to-digital converter; The calibration unit includes a resistor, a capacitor and an analog switch, one end of the resistor and an input end of the analog switch are electrically connected to the inverting input end of the transconductance amplifier at the same time, the other end of the resistor is electrically connected to the output end of the transconductance amplifier, the analog switch and the capacitor are connected in series in sequence to form a capacitor switch branch, and the capacitor switch branch is connected in parallel with the resistor; The MCU is electrically connected to the control unit, the output end of the analog-to-digital converter and the control end of the analog switch respectively; In this embodiment, the calibration circuit further includes: A voltage reference is electrically connected to the reference input terminals of the digital-to-analog converter and the analog-to-digital converter, respectively, and is used to provide a reference operating voltage for the digital-to-analog converter and the analog-to-digital converter; The control unit includes: A digital-to-analog converter, the input end of which is electrically connected to the MCU; an operational amplifier, wherein a non-inverting input terminal is electrically connected to an output terminal of the digital-to-analog converter, an inverting output terminal is electrically connected to a reference electrode, and an output terminal is electrically connected to a counter electrode; In this embodiment, during the calibration process, the calibration circuit controls the analog switch to disconnect the resistor and the capacitor through the MCU, and then calibrates the zero point and gain of the continuous blood glucose meter. After the calibration is completed, the MCU controls the analog switch to close, and the resistor and the capacitor are reconnected. The low-pass filter composed of the transconductance operational amplifier, the resistor and the capacitor starts to work, and the continuous blood glucose meter performs blood glucose detection. If an abnormality occurs in the calibration circuit during the calibration process, the abnormality processing is performed, and the calibration is restarted after the abnormality processing is completed; This embodiment provides a calibration method for a continuous blood glucose meter, such as Figure 7 As shown, including: During the calibration process, the MCU sends a control instruction to control the analog switch to disconnect the resistor and capacitor, so as to calibrate the zero point and gain of the continuous blood glucose meter; When the calibration is completed, the MCU sends a control command to control the analog switch to close, the resistor and capacitor are reconnected, and the low-pass filter composed of the transconductance amplifier, resistor and capacitor starts to work, and the continuous blood glucose meter performs blood glucose detection; If an exception occurs during the calibration process, execute the exception handling, and restart the calibration after the exception handling is completed; In this embodiment, during the calibration and blood glucose testing of the continuous blood glucose meter, the MCU sends control instructions to the digital-to-analog converter, receives data collected by the analog-to-digital converter and performs relevant calculations. Example

[0031] The rest of this embodiment is the same as that of Embodiment 1, except that the capacitor and the analog switch are sequentially connected in series to form a capacitor switch branch, such as Figure 2 shown. Example

[0032] The rest of this embodiment is the same as that of Embodiment 1, except that the calibration unit includes two analog switches, and the analog switch, the capacitor, and the analog switch are sequentially connected in series to form a capacitor switch branch, such as Figure 3 shown.

[0033] The calibration circuit of the continuous blood glucose meter of this embodiment adopts the following method: Figure 4 The calibration test circuit structure shown in FIG. 1 is simulated and verified. The counter electrode and the reference electrode of the electrochemical sensor are electrically connected, and the two electrodes are electrically disconnected from the working electrode. The working electrode is connected to a step current source Iin to simulate the step current generated during the two-point calibration of the line. The initial current is 0nA and the step current rises to 50nA. The resistance is set to 5MOHM and the capacitance is set to 100nF in the simulation circuit. The output voltage Vout of the transconductance amplifier is monitored in the simulation program, and the process of Vout stabilizing over time is read. Through data processing, the curve of the change of the Vout output error over time is obtained, as shown in FIG. Figure 5 It can be seen that by adopting the calibration circuit and calibration method of the present application, the analog switch is disconnected from the capacitor and the resistor, the waiting time is almost 0s, and Vout can be accurately stabilized to an accuracy of one thousandth, thereby achieving precise calibration.

[0034] Using the same RC parameters, step current and output voltage monitoring point, the existing circuit is simulated and verified to obtain the curve of Vout output error changing with time, as shown in Figure 6 It can be seen that the existing calibration method needs to wait for about 10 seconds, and Vout is accurately stabilized to an accuracy of one thousandth to achieve accurate calibration of the system error.

[0035] The calibration circuit of the continuous blood glucose meter proposed in the embodiment of the present invention forms a resistor-capacitor network by connecting a capacitor in series with an analog switch and then connecting the capacitor in parallel with a resistor. The resistor-capacitor network is bridged between the inverting input and output terminals of a transconductance operational amplifier. The analog switch is controlled by an MCU to connect or disconnect the capacitor from the resistor, thereby realizing rapid calibration during the production process, improving production efficiency and measurement accuracy while still maintaining high reliability of the continuous blood glucose meter during use by patients.

[0036] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A calibration circuit for a continuous blood glucose meter, characterized in that: include: a control unit, electrically connected to a counter electrode and a reference electrode of the electrochemical sensor; The acquisition unit includes a transconductance amplifier and an analog-to-digital converter, wherein the inverting input terminal of the transconductance amplifier is electrically connected to the working electrode of the electrochemical sensor, the non-inverting input terminal is electrically connected to the reference level, and the output terminal is electrically connected to the input terminal of the analog-to-digital converter; A calibration unit, comprising a resistor, a capacitor and one or two analog switches, wherein one end of the resistor is electrically connected to the inverting input end of the transconductance amplifier, and the other end is electrically connected to the output end of the transconductance amplifier, the capacitor and one or two analog switches are connected in series to form a capacitor switch branch, and the capacitor switch branch is connected in parallel with the resistor; The MCU is electrically connected to the control unit, the output end of the analog-to-digital converter and the control end of the analog switch respectively.

2. The calibration circuit according to claim 1, characterized in that: The capacitor switch branch is formed by connecting an analog switch and a capacitor in series, or, It is formed by connecting capacitors and analog switches in series, or The analog switch, the capacitor and the analog switch are connected in series in sequence.

3. The calibration circuit according to claim 2, characterized in that: Also includes: A voltage reference, electrically connected to the reference input terminals of the digital-to-analog converter and the analog-to-digital converter, respectively, for providing a reference operating voltage for the digital-to-analog converter and the analog-to-digital converter; The control unit comprises: A digital-to-analog converter, an input end of which is electrically connected to the MCU; An operational amplifier has a non-inverting input terminal electrically connected to the output terminal of the digital-to-analog converter, an inverting output terminal electrically connected to the reference electrode, and an output terminal electrically connected to the counter electrode.

4. The calibration circuit according to claim 1, characterized in that: During the calibration process, the calibration circuit sends a control instruction through the MCU to control the analog switch to disconnect the connection between the resistor and the capacitor, and then calibrates the zero point and gain of the continuous blood glucose meter. After the calibration is completed, the MCU sends a control instruction to control the analog switch to close, the resistor and the capacitor are reconnected, and the low-pass filter composed of the transconductance operational amplifier, the resistor and the capacitor starts to work, and the continuous blood glucose meter performs blood glucose detection.

5. The calibration circuit according to claim 4, characterized in that: If an abnormality occurs in the calibration circuit during the calibration process, the abnormality processing is performed, and the calibration is restarted after the abnormality processing is completed.

6. A method for calibrating a continuous blood glucose meter performed in the calibration circuit according to any one of claims 1 to 5, characterized in that: include: During the calibration process, the MCU sends a control instruction to control the analog switch to disconnect the resistor and the capacitor, so as to calibrate the zero point and gain of the continuous blood glucose meter; After the calibration is completed, the MCU sends a control instruction to control the analog switch to close, the resistor and the capacitor are reconnected, the low-pass filter composed of the transconductance amplifier, the resistor and the capacitor starts to work, and the continuous blood glucose meter performs blood glucose detection.

7. The method according to claim 6, characterized in that Also includes: If an abnormality occurs during the calibration process, the abnormality processing is performed, and the calibration is restarted after the abnormality processing is completed.

8. The method according to claim 7, characterized in that During the calibration and blood glucose testing process of the continuous blood glucose meter, the MCU sends control instructions to the digital-to-analog converter, receives data collected by the analog-to-digital converter and performs relevant calculations.

Images