Method for configuring parameters in disposable electrocardio-electrode glue-to-glue alternating current impedance test

Abstract

A parameter configuration method in a disposable electrocardio-electrode glue-to-glue alternating current impedance test comprises the following steps: (1) selecting a voltage source with an adjustable sine excitation amplitude, preparing a reference resistor R0 with an adjustable resistance value, and preparing a glue-to-glue disposable electrocardio-electrode pair as a test object; (2) connecting the selected and prepared adjustable voltage source, a reference resistor R0 and an electrode pair to be tested in series to form a test circuit; (3) repeatedly testing the alternating current impedance spectrum of the to-be-tested electrode pair for multiple times according to the pairing of one amplitude of sine excitation of the given voltage source and one resistance value of the reference resistor R0, and calculating a repeatability index; (4) changing pairs of the sine excitation amplitude of enough voltage sources and the resistance value of the reference resistor R0, repeatedly testing the alternating-current impedance spectrum of the electrode pair for multiple times under each pair, and calculating a repeatability index value of the alternating-current impedance spectrum; and (5) comparing the repeatability index values to obtain optimal pairing.

Description

Technical Field

[0001] The present application relates to a method for parameter configuration in the testing of the glue-to-glue AC impedance of a disposable electrocardiogram electrode.

[0002] Disposable electrocardiogram electrodes, also known as electrode patches, are widely used in electrocardiogram devices, especially electrocardiogram monitoring devices. The most important performance of a disposable electrocardiogram electrode is reflected in the magnitude of the contact impedance when measuring an electrocardiogram. The smaller the contact impedance, the better. Industry standard YY / T0196-2005 states that under the condition of strict skin treatment, the magnitude of the contact impedance of a disposable electrocardiogram electrode when measuring an electrocardiogram is positively correlated with the magnitude of the glue-to-glue AC impedance of a pair of electrode patches. The glue-to-glue AC impedance test of a disposable electrocardiogram electrode is the primary test stipulated by its industry standard.

[0003] To test the glue-to-glue AC impedance of a disposable electrocardiogram electrode, it can be achieved by connecting a sinusoidal voltage source in series with a reference resistor R0 and the gel electrode pair to be tested, as Figure 1 shown. The principle is: synchronously record the sinusoidal voltages and across R0 and the impedance of the electrode pair to be tested, then the complex impedance to be tested can be calculated, including the real part resistance and the imaginary part reactance.

[0004] When testing the glue-to-glue AC impedance of a disposable electrocardiogram electrode by the above method, it is necessary to configure the amplitude of the sinusoidal wave excited by the voltage source and the magnitude of the series reference resistor R0. Background Art

[0005] Industry standard YY / T0196-2005 stipulates that when testing the AC impedance of a glue-to-glue connected disposable electrocardiogram electrode at 10 Hz, the peak-to-peak value of the test current should not exceed 100 μA. It is recommended that a sinusoidal signal voltage source and a resistor of 1 MΩ or larger (i.e., R0) be connected in series with the electrode pair to be tested to generate the test current.

[0006] In fact, if the peak-to-peak value of the sinusoidal voltage applied by the voltage source is 2 V and the series reference resistor R0 is 1 MΩ or larger, then the peak-to-peak value of the test current is less than 2 μA, much less than 100 μA. One consideration for the industry standard to recommend using a conservative and relatively large reference resistor is to prevent the test current from being too large and affecting the charged state of the electrode pair, thereby affecting the stability of the electrode AC impedance.

[0007] However, under normal circumstances, the AC impedance value of the gel electrode pair is not very large, generally around 1 kΩ. An overly large reference resistor R0 will result in too small a voltage division across the two ends of the electrode pair to be tested, increasing the quantization error during the analog-to-digital conversion of the detection circuit, thereby affecting the estimation accuracy of the AC impedance to be tested.

[0008] There has been no literature discussing the optimization of the configuration of the amplitude of the sinusoidal excitation of the voltage source and the resistance value of the reference resistor R0 when testing the AC impedance value of a gel electrode by a sinusoidal voltage source in series with a reference resistor R0. A good optimized configuration scheme should be a scheme with good repeatability of the measured AC impedance spectrum of the electrode pair. Summary of the Invention

[0009] Object of the Invention

[0010] A parameter configuration scheme for testing the AC impedance of a gel electrode pair by a sinusoidal voltage source in series with a reference resistor R0 is proposed, including the optimal configuration scheme of the amplitude of the excitation sine wave and the size parameter of the reference resistor R0, aiming at having high repeatability of the measured AC impedance spectrum of the electrode pair under this parameter configuration.

[0011] Technical Solution

[0012] A method for parameter configuration in the AC impedance test of a disposable electrocardiogram electrode from gel to gel, characterized by including the following steps: (1) Select a voltage source with adjustable sinusoidal excitation amplitude, prepare a reference resistor R0 with adjustable resistance value, and prepare a disposable electrocardiogram electrode pair from gel to gel as the test object; (2) Use the selected and prepared adjustable voltage source, reference resistor R0 and the electrode pair to be tested to form a test circuit in series, as Figure 1 shown; (3) For each pairing of the amplitude of the sinusoidal excitation of the voltage source and the resistance value of the reference resistor R0, repeat the test of the AC impedance spectrum of the electrode pair to be tested multiple times and calculate the repeatability index; (4) Change the pairing of the amplitude of the sinusoidal excitation of the voltage source and the resistance value of the reference resistor R0, and then repeat the test of the AC impedance spectrum of the electrode pair to be tested multiple times and calculate the corresponding repeatability index, and continue until enough pairings of the amplitude of the sinusoidal excitation and the resistance value of the reference resistor R0 are changed. For each pairing, repeat the test of the AC impedance spectrum of the electrode pair multiple times and calculate its repeatability index value; (5) Compare the magnitudes of the repeatability index values of the AC impedance spectra of the electrode pairs under all the calculated pairings, and determine the pairing of the excitation voltage amplitude and the value of the reference resistor R0 corresponding to the best repeatability index value as the optimal pairing.

[0013] According to the above method for parameter configuration in the AC impedance test of a disposable electrocardiogram electrode from gel to gel, when changing the pairing of the amplitude of the sinusoidal excitation of the voltage source and the resistance value of the reference resistor R0 in step (4) to search for the optimal pairing, a strategy for simplifying the search can be considered. Its feature is that the resistance value of R0 can be first determined to be a value similar to it according to the prior knowledge of the magnitude of the AC impedance of the electrode pair, such as set to 10 kΩ, and then only change the amplitude of the sinusoidal excitation of the voltage source to form one pairing after another, and then repeat the test of the AC impedance spectrum of the electrode pair multiple times for each pairing situation and calculate its repeatability index value.

[0014] According to the above method for parameter configuration in the glue-to-glue AC impedance test of a disposable electrocardiogram electrode, when searching for the optimal pairing by changing the pairing of the sinusoidal excitation amplitude of the voltage source and the resistance value of the reference resistor R0 in step (4), a strategy for simplifying the search can be considered. It is characterized in that: (a) According to the prior knowledge of the AC impedance of the electrode pair, the resistance value of R0 can be first determined as a value similar to it, such as set to 10 kΩ. Then, only change the sinusoidal excitation amplitude of the voltage source to form pairs one by one, and then repeat the measurement of the AC impedance spectrum of the electrode pair multiple times for each pair and calculate its repeatability index value; (b) Determine the sinusoidal excitation amplitude of the voltage source with the best repeatability index in step (a). Then, only change the size of the reference resistor R0 to form pairs one by one, and then repeat the measurement of the AC impedance spectrum of the electrode pair multiple times for each pairing situation, and calculate its corresponding repeatability index value, so as to finally determine the reference resistor R0 based on the best value of the repeatability index.

[0015] According to the above method for parameter configuration in the glue-to-glue AC impedance test of a disposable electrocardiogram electrode, the repeatability index needs to be calculated. Its characteristic is that the repeatability index uses the average correlation coefficient, and it can be calculated as follows:

[0016] If m complex impedance spectra are monitored under a certain parameter configuration, and each complex impedance spectrum records the complex impedance at n frequency points. Assuming that one of the complex impedance spectra is X and the average complex impedance spectrum of the m complex impedance spectra is Y, then both X and Y are complex vectors containing n elements. The Pearson correlation coefficient between them is defined as follows.

[0017]

[0018] Among them, is the mean value of the complex impedance spectrum X, is the mean value of the average complex impedance spectrum Y; in this way, the Pearson correlation coefficients r1, r2,... r m of the m monitored complex impedance spectra and the average complex impedance spectrum Y can be calculated in total. Thus, the repeatability index is defined as the average correlation coefficient r:

[0019]

[0020] Beneficial effects

[0021] The optimized parameter configuration scheme obtained according to this solution has the highest repeatability when measuring the glue-to-glue AC impedance of a disposable electrocardiogram electrode. As can be seen from Tables 1 and 2, when the excitation voltage amplitude is 1280 mV and the reference resistor R0 is 10 kΩ, the average correlation coefficient of 10 measurements can reach 0.9998, which is significantly better than other parameter combinations.

[0022] Table 1 Repeatability of electrode patch glue-to-glue measurement with a 10 kΩ reference resistor at different test voltages

[0023]

[0024] Table 2 Repeatability of measurements of electrode adhesive pairs with a test voltage of 1280 mV and different reference resistances

[0025] Description of the Drawings

[0026] Figure 1 Measurement equivalent circuit diagram

[0027] Figure 2 Schematic diagram of the instrument for measuring the AC impedance spectrum of the test electrode pair in the test of the solution of this application

[0028] Figure 3 Schematic diagram of the results of 10 measurements of the AC impedance spectrum of the electrode adhesive pair under an excitation voltage of 80 mV when a 10 kΩ reference resistance is selected. The horizontal axes of the upper and lower figures are both frequency f, with the unit of Hz; the upper figure is the real part resistance spectrum, and the vertical axis is resistance, with the unit of ohm; the lower figure is the imaginary part reactance spectrum, and the vertical axis is reactance, with the unit of ohm.

[0029] Figure 4 Schematic diagram of 10 measurements of the AC impedance spectrum of the electrode adhesive pair under an excitation voltage of 320 mV when a 10 kΩ reference resistance is selected. The horizontal axes of the upper and lower figures are both frequency f, with the unit of Hz; the upper figure is the real part resistance spectrum, and the vertical axis is resistance, with the unit of ohm; the lower figure is the imaginary part reactance spectrum, and the vertical axis is reactance, with the unit of ohm.

[0030] Figure 5 Schematic diagram of 10 measurements of the AC impedance spectrum of the electrode adhesive pair under an excitation voltage of 1280 mV when a 10 kΩ reference resistance is selected. The horizontal axes of the upper and lower figures are both frequency f, with the unit of Hz; the upper figure is the real part resistance spectrum, and the vertical axis is resistance, with the unit of ohm; the lower figure is the imaginary part reactance spectrum, and the vertical axis is reactance, with the unit of ohm.

[0031] Figure 6 Schematic diagram of 10 measurements of the AC impedance spectrum of the electrode adhesive pair with a 100 Ω series resistance selected under an excitation voltage of 1280 mV. The horizontal axes of the upper and lower figures are both frequency f, with the unit of Hz; the upper figure is the real part resistance spectrum, and the vertical axis is resistance, with the unit of ohm; the lower figure is the imaginary part reactance spectrum, and the vertical axis is reactance, with the unit of ohm.

[0032] Figure 7, Schematic diagram of 10 - time measurement of the AC impedance spectrum of electrode glue - to - glue with a 10kΩ reference resistor under a 1280mV excitation voltage. The horizontal axes of the upper and lower figures are both frequency f, with the unit of Hz; the upper figure is the real - part resistance spectrum, and the vertical axis is resistance, with the unit of ohm; the lower figure is the imaginary - part reactance spectrum, and the vertical axis is reactance, with the unit of ohm.

[0033] Figure 8 , Schematic diagram of 10 - time measurement of the AC impedance spectrum of electrode glue - to - glue with a 1MΩ reference resistor under a 1280mV excitation voltage. The horizontal axes of the upper and lower figures are both frequency f, with the unit of Hz; the upper figure is the real - part resistance spectrum, and the vertical axis is resistance, with the unit of ohm; the lower figure is the imaginary - part reactance spectrum, and the vertical axis is reactance, with the unit of ohm.

[0034] Figure 9 , Schematic diagram of a certain brand of electrode patch used in the embodiment. Specific implementation manner

[0035] Example. Prepare 1 pair of electrodes of a certain brand, which is the Schindler brand, as Figure 9 shown; prepare a qualified low - frequency impedance spectrum analyzer, as Figure 2 shown, which includes a voltage source with an adjustable sinusoidal excitation amplitude and an adjustable reference resistor. Measure the AC impedance spectrum data of the electrode pair in the range of 0.1Hz - 100Hz. The specific implementation steps are as follows:

[0036] (1) Use a constant - voltage type low - frequency impedance spectrum analyzer with the principle as Figure 1 shown to paste the pair of electrode patches glue - to - glue;

[0037] (2) Each time when measuring the impedance spectrum, select 20 frequency points of 0.10Hz, 0.14Hz, 0.21Hz, 0.30Hz, 0.43Hz, 0.61Hz, 0.89Hz, 1.27Hz, 1.83Hz, 2.64Hz, 3.80Hz, 5.45Hz, 7.85Hz, 11.29Hz, 16.24Hz, 23.36Hz, 33.60Hz, 48.33Hz, 69.52Hz, 100.00Hz within the frequency band of 0.1Hz - 100Hz, and record their complex impedances;

[0038] (3) When the reference resistor is 10kΩ, test the AC impedance spectrum of the same electrode patch glue - to - glue 10 times respectively under the conditions that the excitation sinusoidal voltage amplitudes are 80mV, 320mV, and 1280mV. The interval between each test is 30 seconds. Calculate the average correlation coefficient of the 10 measurements under the same set of parameter configurations, as shown in Table 1, and draw the 10 - time test situations of each excitation voltage in the same figure, as Figures 3 - 5 shown. From Table 1 and Figures 3 - 5Look, when measuring the AC impedance of the electrode adhesive to the glue, with a reference resistance of 10 kΩ, the greater the amplitude of the sinusoidal excitation voltage, the closer the average correlation coefficient of 10 measurements is to 1, and the higher the repeatability of the measurement;

[0039] (4) When the excitation voltage amplitude is 1280 mV, the AC impedance spectra of the same electrode adhesive to the glue are tested 10 times respectively under the conditions of reference resistances of 100 Ω, 10 kΩ, and 1 MΩ, with an interval of 30 seconds between each test. Calculate the average correlation coefficient of 10 measurements under the same set of parameter configurations, as shown in Table 2, and draw the 10 test cases of each series resistance in the same graph, as Figures 6 - 8 shown. From Table 2 and Figures 6 - 8 look, when measuring the AC impedance of the electrode adhesive to the glue, the repeatability of using a reference resistance of 10 kΩ for 10 measurements is the highest.

Claims

1. A method for parameter configuration in a disposable ECG electrode gel-to-gel AC impedance test, the characteristics of which are: The method comprises the following steps: (1) selecting a voltage source with adjustable sinusoidal excitation amplitude, preparing a reference resistor R0 with adjustable resistance value, and preparing a pair of disposable ECG electrodes as a test object; (2) connecting the selected and prepared adjustable voltage source, the reference resistor R0 and the electrode pair to be tested in series to form a test circuit; (3) For each pairing of a given voltage source sinusoidal excitation amplitude and a reference resistor R0 resistance value, repeatedly test the AC impedance spectrum of the electrode pair to be tested multiple times, and calculate the repeatability index; (4) Change the pairing of the voltage source sinusoidal excitation amplitude and the reference resistor R0 resistance value, and then repeatedly test the AC impedance spectrum of the electrode pair to be tested multiple times and calculate the corresponding repeatability index, and continue until enough sinusoidal excitation amplitudes and reference resistor R0 pairs are changed, and the AC impedance spectrum of the electrode pair is repeatedly tested multiple times under each pairing and its repeatability index value is calculated; (5) Compare the values ​​of the repeatability index of the AC impedance spectra of all electrode pairs under the calculation, and determine the pairing of the excitation voltage amplitude and the reference resistance R0 value corresponding to the best repeatability index value as the optimal pairing.

2. According to the method for parameter configuration in the disposable ECG electrode gel-to-gel AC impedance test of claim 1, when changing the pairing of the voltage source sinusoidal excitation amplitude and the reference resistor R0 resistance value to search for the optimal pairing in step (4), a strategy of simplifying the search can be considered, wherein: Based on the prior knowledge of the AC impedance of the electrode pair, the R0 resistance can be determined to be a similar value, such as 10kΩ. Then, only the sinusoidal excitation amplitude of the voltage source is changed to form pairs. The AC impedance spectrum of the electrode pair is tested repeatedly for each pairing and its repeatability index value is calculated.

3. According to the method for parameter configuration in the disposable ECG electrode gel-to-gel AC impedance test of claim 1, when changing the pairing of the voltage source sinusoidal excitation amplitude and the reference resistor R0 resistance value to search for the optimal pairing in step (4), a simplified search strategy can be considered, characterized in that: (a) Based on the prior knowledge of the AC impedance of the electrode pair, the R0 resistance can be determined to be a similar value, such as 10 kΩ. Then, only the voltage source sinusoidal excitation amplitude is changed to form pairs, and the AC impedance spectrum of the electrode pair is tested repeatedly for each pair and its repeatability index value is calculated. (b) Determine the voltage source sinusoidal excitation amplitude with the best repeatability index in step (a), then only change the reference resistance R0 to form pairs, and then repeat the electrode pair AC impedance spectrum test for each pairing multiple times, and calculate the corresponding repeatability index value, so as to finally determine the reference resistance R0 based on the best repeatability index value.

4. According to the method for parameter configuration in the disposable ECG electrode gel-to-gel AC impedance test of claim 1, it is necessary to calculate the repeatability index, which is characterized by: The repeatability index uses the average correlation coefficient, which can be calculated as follows: If m complex impedance spectra are monitored under a certain parameter configuration, each complex impedance spectrum records the complex impedance of n frequency points. Assuming that one of the complex impedance spectra is X and the average complex impedance spectrum of m complex impedance spectra is Y, then X and Y are both complex vectors containing n elements, and the Pearson correlation coefficient between them is defined as follows: in, is the mean value of the complex impedance spectrum X, is the mean of the average complex impedance spectrum Y; in this way, the Pearson correlation coefficients r1, r2, ..., r between the monitored m complex impedance spectra and the average complex impedance spectrum Y can be calculated. m , thus defining the repeatability index as the average correlation coefficient

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