Calibration circuit and method for continuous blood glucose meter

Abstract

The present invention relates to the technical field of blood glucose meter calibration, and specifically discloses a calibration circuit and method for a continuous blood glucose meter. The calibration circuit includes: a control unit electrically connected to a counter electrode and a reference electrode of an electrochemical sensor; an acquisition unit including a transconductance amplifier and an analog-to-digital converter, wherein the inverting input of the transconductance amplifier is electrically connected to the working electrode of the electrochemical sensor, the non-inverting input is electrically connected to a reference level, and the output is electrically connected to the input of the analog-to-digital converter; a calibration unit including a resistor, a capacitor, and an analog switch, wherein the capacitor and the analog switch are connected in series and in parallel with the resistor to form a resistor-capacitor network, and the resistor-capacitor network is connected across the inverting input and output of the transconductance amplifier; and an MCU electrically connected to the control unit, the output of the analog-to-digital converter, and the control end of the analog switch, respectively. The present invention controls the analog switch by the MCU to connect or disconnect the capacitor from the resistor, thereby achieving rapid calibration during the production process and improving production efficiency.

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 meters (CGMs) enable real-time monitoring of blood glucose levels. They are convenient to wear and widely accepted by patients, with industry forecasts predicting a 30% annual growth rate in market demand by 2030. However, to improve accuracy and stability during use, current CGMs utilize very low analog signal acquisition speeds. Consequently, calibration time during manufacturing is limited, hindering productivity and impacting product costs.

[0003] When a patient uses a continuous blood glucose meter, various external interference sources may occur, and these interference signals can easily couple into the sensor's input signal. Interference signals may be power frequency interference or other alternating signals. The blood glucose concentration signal sensed by a continuous blood glucose meter changes very slowly, such as on the order of tens of seconds or minutes. This interference signal can generally be filtered out using a low-pass filter with a very low cutoff frequency. This low-pass filter cutoff frequency is typically set to less than 1Hz. During the production process, blood glucose meters require a calibration process to correct the zero-point error and gain error introduced by the system's circuitry to improve accuracy. Given the system's high accuracy requirements, the calibration process can take several seconds or even more than ten seconds, significantly reducing 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 response to the shortcomings of the existing technology, 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 in parallel with a resistor. The resistor-capacitor network is connected 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 achieving rapid calibration during the production process. While improving production efficiency and measurement accuracy, the high reliability of the continuous blood glucose meter during patient use can still be maintained.

[0006] To achieve the above objectives, the present invention provides, in a first aspect, a calibration circuit for a continuous blood glucose meter, a control unit electrically connected to a counter electrode and a reference electrode of an electrochemical sensor;

[0007] An acquisition unit, comprising a transconductance operational amplifier and an analog-to-digital converter, wherein the inverting input terminal of the transconductance operational 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;

[0008] 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 terminal of the transconductance amplifier, and the other end is electrically connected to the output terminal of the transconductance amplifier, the capacitor and the 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;

[0009] 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.

[0010] A second aspect of the present invention provides a method for calibrating a continuous blood glucose meter performed in the above-mentioned calibration circuit, comprising:

[0011] During the calibration process, the MCU sends a control instruction to control the analog switch to disconnect the resistor and the capacitor, thereby calibrating the zero point and gain of the continuous blood glucose meter;

[0012] After the calibration is completed, the MCU sends a control instruction to control the analog switch to close, the resistor and capacitor are reconnected, 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.

[0013] The beneficial effects of the present invention include:

[0014] 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 in parallel with a resistor. The resistor-capacitor network is connected between the inverting input and output of a transconductance operational 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, it still maintains the high reliability of the continuous blood glucose meter during patient use.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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 with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0017] Figure 1 This is a structural diagram of a specific embodiment of the calibration circuit of the continuous blood glucose meter proposed by the present invention.

[0018] Figure 2 This is a structural schematic diagram of another specific embodiment of the calibration circuit of the continuous blood glucose meter proposed by the present invention.

[0019] Figure 3 This is a schematic structural diagram of a third specific embodiment of the calibration circuit of the continuous blood glucose meter proposed in the present invention.

[0020] Figure 4 This is a schematic structural diagram of a calibration test circuit of a third specific embodiment of the calibration circuit of the continuous blood glucose meter proposed by the present invention.

[0021] Figure 5 This is a schematic diagram of a calibration test curve of a third specific embodiment of the calibration circuit of the continuous blood glucose meter proposed by the present invention.

[0022] Figure 6 A schematic diagram of a calibration test curve of an existing calibration circuit.

[0023] Figure 7 The figure is a flow chart of a specific embodiment of the calibration method of the continuous blood glucose meter proposed in the present invention. DETAILED DESCRIPTION

[0024] 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.

[0025] In the present invention, unless otherwise specified, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of a device in normal use, and "inner" and "outer" refer to positions relative to the device's outline. Furthermore, the terms "first, second, and third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Therefore, features defined as "first, second, and third" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise explicitly and specifically defined.

[0026] The present invention provides a calibration circuit for a continuous blood glucose meter, such as Figure 1 Shown, including:

[0027] a control unit electrically connected to the counter electrode and the reference electrode of the electrochemical sensor;

[0028] The acquisition unit includes a transconductance operational amplifier and an analog-to-digital converter, wherein the inverting input terminal of the transconductance operational 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;

[0029] A calibration unit includes a resistor, a capacitor, and one or two analog switches, wherein one end of the resistor is electrically connected to the inverting input terminal of the transconductance operational amplifier, and the other end is electrically connected to the output terminal of the transconductance operational amplifier, the capacitor and the 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;

[0030] 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.

[0031] 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. The resistor-capacitor network is connected 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 achieving rapid calibration during the production process. While improving production efficiency and measurement accuracy, the high reliability of the continuous blood glucose meter during patient use can still be maintained.

[0032] According to the present invention, the capacitor switch branch is formed by sequentially connecting an analog switch and a capacitor in series, or,

[0033] It is formed by connecting capacitors and analog switches in series, or

[0034] The analog switch, the capacitor and the analog switch are connected in series in sequence.

[0035] According to the present invention, it also includes:

[0036] A voltage reference is 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;

[0037] The control unit includes:

[0038] A digital-to-analog converter, the input end of which is electrically connected to the MCU;

[0039] 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.

[0040] 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.

[0041] 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.

[0042] The present invention also provides a method for calibrating a continuous blood glucose meter performed in the above-mentioned calibration circuit, comprising:

[0043] During the calibration process, the MCU sends a control instruction to control the analog switch to disconnect the resistor and capacitor to calibrate the zero point and gain of the continuous blood glucose meter;

[0044] After 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.

[0045] According to the present invention, it also includes:

[0046] If an exception occurs during the calibration process, perform exception handling, and restart the calibration after the exception handling is completed.

[0047] According to the present invention, 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.

[0048] The present invention will be described in more detail below through specific examples. Example

[0049] like Figure 1 As shown, this embodiment provides a calibration circuit for a continuous blood glucose meter, comprising:

[0050] a control unit electrically connected to the counter electrode and the reference electrode of the electrochemical sensor;

[0051] The acquisition unit includes a transconductance operational amplifier and an analog-to-digital converter, wherein the inverting input terminal of the transconductance operational 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;

[0052] A calibration unit includes a resistor, a capacitor, and an analog switch, wherein 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, the other end of the resistor is electrically connected to the output end of the transconductance amplifier, the analog switch and the capacitor are sequentially connected in series to form a capacitor switch branch, and the capacitor switch branch is connected in parallel with the resistor;

[0053] 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;

[0054] In this embodiment, the calibration circuit further includes:

[0055] A voltage reference is 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;

[0056] The control unit includes:

[0057] A digital-to-analog converter, the input end of which is electrically connected to the MCU;

[0058] an operational amplifier having 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;

[0059] In this embodiment, during the calibration process, the calibration circuit calibrates the zero point and gain of the continuous blood glucose meter by sending a control instruction through the MCU to control the analog switch to disconnect the resistor and capacitor. After the calibration is completed, the MCU sends a control instruction to control the analog switch to close, reconnecting the resistor and capacitor. The low-pass filter composed of the transconductance operational amplifier, resistor, and capacitor starts to operate, and the continuous blood glucose meter performs blood glucose detection.

[0060] 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;

[0061] This embodiment provides a calibration method for a continuous blood glucose meter, such as Figure 7 Shown, including:

[0062] During the calibration process, the MCU sends a control instruction to control the analog switch to disconnect the resistor and capacitor to calibrate the zero point and gain of the continuous blood glucose meter;

[0063] After 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 working, and the continuous blood glucose meter performs blood glucose testing;

[0064] If an exception occurs during the calibration process, execute the exception handling, and restart the calibration after the exception handling is completed;

[0065] In this embodiment, 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. Example

[0066] 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

[0067] 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 switches, capacitors, and analog switches are sequentially connected in series to form a capacitor switch branch, such as Figure 3 shown.

[0068] 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 is simulated and verified. The counter electrode and 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 method. 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 operational 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 Vout output error over time is obtained, as shown in FIG. Figure 5 It can be seen that by using 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.

[0069] Using the same resistance and capacitance parameters, step current and the same 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 requires waiting for about 10 seconds for Vout to stabilize accurately to an accuracy of one thousandth in order to achieve accurate calibration of the system error.

[0070] The calibration circuit of the continuous blood glucose meter proposed in an embodiment of the present invention forms a resistor-capacitor network by connecting a capacitor in series with an analog switch and then in parallel with a resistor. The resistor-capacitor network is connected between the inverting input and output of a transconductance operational 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, improving production efficiency and measurement accuracy while still maintaining the high reliability of the continuous blood glucose meter during patient use.

[0071] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations 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 the counter electrode and the reference electrode of the electrochemical sensor; An acquisition unit, comprising a transconductance operational amplifier and an analog-to-digital converter, wherein the inverting input terminal of the transconductance operational 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 terminal of the transconductance amplifier, and the other end is electrically connected to the output terminal of the transconductance amplifier, the capacitor and the 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; MCU, electrically connected to the control unit, the output end of the analog-to-digital converter and the control end of the analog switch respectively; The capacitor switch branch is formed by sequentially 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.

2. The calibration circuit according to claim 1, wherein: 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.

3. The calibration circuit according to claim 1, wherein: During the calibration process, the calibration circuit calibrates the zero point and gain of the continuous blood glucose meter after the MCU issues a control instruction to control the analog switch to disconnect the resistor and capacitor. After the calibration is completed, the MCU issues 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 operational amplifier, resistor and capacitor starts to work, and the continuous blood glucose meter performs blood glucose detection.

4. The calibration circuit according to claim 3, wherein: If an abnormality occurs in the calibration circuit during the calibration process, abnormality processing is performed, and after the abnormality processing is completed, the calibration is restarted.

5. A method for calibrating a continuous blood glucose meter performed in the calibration circuit according to any one of claims 1 to 4, 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, thereby calibrating 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 capacitor are reconnected, 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.

6. The method according to claim 5, characterized in that Also includes: If an exception occurs during the calibration process, the exception handling is performed, and after the exception handling is completed, the calibration is restarted.

7. The method according to claim 6, 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.

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