System for measuring electrode contact impedance and impedance measurement method

Abstract

This application discloses a system and method for measuring electrode contact impedance. The system includes at least two measuring electrodes, at least two AC excitation sources, a driving electrode, and a controller. The at least two measuring electrodes are connected to the skin of a subject to measure physiological parameters, forming at least two sets of measuring electrodes. The at least two AC excitation sources are respectively connected to the at least two measuring electrodes, wherein the AC excitation sources connected to the measuring electrodes of different sets of measuring electrodes operate at different frequencies. The driving electrode is connected to the skin of the subject and provides a common-mode potential to the measuring electrodes. The controller acquires the voltage and current at the measuring electrodes and calculates the contact impedance between each measuring electrode and the skin of the subject based on the acquired voltage and current. This application can acquire the contact impedance of the measuring electrodes during physiological parameter measurement, thus providing an indication of the quality of the physiological signal.

Description

Technical Field

[0001] This application relates to the field of medical measurement, and in particular to a system and method for measuring the electrode contact impedance between human skin and an electrode attached to human skin. Background Technology

[0002] The measurement of human electrophysiological signals is widely used in clinical practice. The measured signals include electrocardiogram (ECG), electroencephalogram (EEG), and electromyography (EMG), primarily used for patient diagnosis and routine monitoring. The electrophysiological signals generated by the human body are typically very weak; for example, ECG and EMG signals have amplitudes in the mV range, while EEG signals have amplitudes in the μV range. These weak electrophysiological signals are easily affected by interference from the measurement system and the external environment. To obtain good physiological signal quality, it is necessary to monitor the state of the measurement system and prevent changes in the system from affecting the accurate measurement of physiological signals.

[0003] Typically, the measurement of human electrophysiological signals is achieved by connecting measuring electrodes to the body non-invasively or invasively. Non-invasive methods involve attaching electrode pads or conductive gel to the skin surface and then connecting the body and the measurement system via the measuring electrodes. Invasive methods involve inserting needle electrodes under the skin and then connecting them to the skin via cables. Because needle electrodes are invasive, non-invasive electrode pads, such as self-adhesive electrode pads or electrode pads fixed to the body surface with conductive gel, are more commonly used clinically. There is contact impedance between the measuring electrodes and the skin. The magnitude of this contact impedance reflects the quality of the connection between the physiological signal measurement system and the body, directly affecting the measurement quality of the current physiological signal, and potentially influencing the analysis and interpretation of the measured physiological signal by medical personnel.

[0004] Therefore, it is necessary to provide an accurate and synchronous method for monitoring electrode contact impedance, so that when the electrode contact impedance is too high and affects the quality of the measured physiological signal, medical staff can be promptly alerted to intervene. Summary of the Invention

[0005] This application provides a system and method for measuring electrode contact impedance, which can accurately and synchronously monitor the contact impedance of electrodes when measuring human electrophysiological signals, thereby providing a reference for the signal quality of human electrophysiological signals.

[0006] On one hand, embodiments of this application provide a system for measuring electrode contact impedance. The system includes at least two measuring electrodes, at least two AC excitation sources, a driving electrode, and a controller. The at least two measuring electrodes are connected to the skin of a subject to measure physiological parameters, wherein the at least two measuring electrodes form at least two groups of measuring electrodes. The current output terminals of the at least two AC excitation sources are respectively connected to the at least two measuring electrodes, wherein the operating frequencies of the AC excitation sources connected to the measuring electrodes of different groups of measuring electrodes are different. The driving electrode is connected to the skin of the subject to provide a common-mode potential for the at least two measuring electrodes. The controller is coupled to each measuring electrode to acquire the voltage and current at each measuring electrode and calculate the contact impedance between each measuring electrode and the skin of the subject based on the voltage and current at each measuring electrode.

[0007] On the other hand, embodiments of this application provide an impedance measurement method, the method comprising: connecting at least two measuring electrodes to the skin of a subject, wherein the at least two measuring electrodes form at least two measuring electrode groups; providing current to the at least two measuring electrodes respectively through at least two AC excitation sources, wherein the current output terminals of the at least two AC excitation sources are respectively connected to the two measuring electrodes, and the operating frequencies of the AC excitation sources connected to the measuring electrodes of different measuring electrode groups are different; acquiring the voltage and current at each measuring electrode, and calculating the contact impedance between each measuring electrode and the skin of the subject based on the voltage and current at each measuring electrode.

[0008] Furthermore, a system for measuring electrode contact impedance is also provided. The system includes at least one measuring electrode, at least one AC excitation source, a driving electrode, and a controller. The at least one measuring electrode is used to connect to the skin of a subject for measuring physiological parameters, wherein the at least one measuring electrode forms at least one group of measuring electrodes. The current output terminal of the at least one AC excitation source is connected to each of the at least one measuring electrode, wherein the operating frequencies of the AC excitation sources connected to the measuring electrodes of different groups of measuring electrodes are different. The driving electrode is used to connect to the skin of the subject and provide a common-mode potential for the plurality of measuring electrodes. The controller is coupled to the current output terminal of each AC excitation source and each measuring electrode, and is used to acquire the voltage and current at each measuring electrode, and calculate the contact impedance between each measuring electrode and the skin of the subject based on the voltage and current at each measuring electrode.

[0009] Furthermore, an impedance measurement method is also provided, applied in a system for measuring electrode contact impedance. The method includes: connecting at least one measuring electrode to the skin of a subject, wherein the at least one measuring electrode forms at least one measuring electrode group; providing current to the at least one measuring electrode through at least one AC excitation source, wherein the current output terminal of the at least one AC excitation source is connected to the at least one measuring electrode, and the operating frequencies of the AC excitation sources connected to the measuring electrodes of different measuring electrode groups are different; acquiring the voltage and current at each measuring electrode, and calculating the contact impedance between each measuring electrode and the skin of the subject based on the voltage and current at each measuring electrode.

[0010] In this application, an AC excitation source provides AC power to the measuring electrodes, which does not interfere with physiological signals. This allows for the simultaneous measurement / monitoring of physiological parameters by the measuring electrodes, while also acquiring the contact impedance between each measuring electrode and the subject's skin, thus providing an indication of the quality of the physiological signals measured. Furthermore, the AC excitation sources connected to different measuring electrode groups operate at different frequencies, ensuring that each measuring electrode group does not affect the measurement of contact impedance in other groups, improving accuracy and synchronization. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of a system for measuring electrode contact impedance according to an embodiment of this application.

[0015] Figure 2This is a diagram of the internal module architecture of the controller in one embodiment of this application.

[0016] Figure 3 This is a schematic diagram of a monitoring device for applying a system for measuring electrode contact impedance according to an embodiment of this application.

[0017] Figure 4 This is a schematic diagram showing the measurement signal waveform and contact impedance indication in one embodiment of this application.

[0018] Figure 5 This is a schematic diagram showing the measurement signal waveform and contact impedance indication in another embodiment of this application.

[0019] Figure 6 This is a schematic diagram of a system for measuring electrode contact impedance according to another embodiment of this application.

[0020] Figure 7 This is a flowchart of an impedance measurement method according to an embodiment of this application.

[0021] Figure 8 This is a flowchart of an impedance measurement method according to another embodiment of this application.

[0022] Figure 9 This is a flowchart of an impedance measurement method in another embodiment of this application. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] In this application, "connection" or "coupling" includes both direct connection and indirect connection.

[0025] Please refer to the following: Figure 1 This is a schematic diagram of a system 100 for measuring electrode contact impedance according to an embodiment of this application. The system 100 includes at least two measuring electrodes 1, at least two AC excitation sources 2, a driving electrode 3, and a controller 4.

[0026] The at least two measuring electrodes 1 are used to connect to the skin 101 of the subject for measuring physiological parameters, wherein the at least two measuring electrodes 1 form at least two measuring electrode groups 10. Each AC excitation source 2 includes an AC output terminal 21, and the at least two AC excitation sources 2 are respectively connected to the at least two measuring electrodes 1, that is, the current output terminals 21 of the at least two AC excitation sources are respectively connected to each measuring electrode in the at least two measuring electrode groups 10, wherein the operating frequencies of the AC excitation sources 2 connected to the measuring electrodes 1 of different measuring electrode groups 10 are different. The driving electrode 3 is used to connect to the skin 101 of the subject and provide a common-mode potential for the at least two measuring electrodes 1. The controller 4 is coupled to the current output terminal 21 of each AC excitation source 2 and each measuring electrode 1, and is used to acquire the voltage and current at each measuring electrode 1, and calculate the contact impedance between each measuring electrode 1 and the skin 101 of the subject based on the voltage and current at each measuring electrode 1.

[0027] Therefore, in this application, the AC excitation source 2 provides AC power to the measuring electrode 1, which does not interfere with the physiological signals. This allows for the simultaneous measurement / monitoring of physiological parameters by the measuring electrode 1, while also acquiring the contact impedance between each measuring electrode 1 and the subject's skin 101, thus providing an indication of the quality of the physiological signals measured by the measuring electrode 1. Furthermore, the AC excitation sources 2 connected to the measuring electrodes 1 of different measuring electrode groups 10 operate at different frequencies. Therefore, each measuring electrode group does not affect the measurement of the contact impedance of the measuring electrodes 1 of other measuring electrode groups 10, improving accuracy and achieving synchronization.

[0028] The contact impedance between each measuring electrode 1 and the skin 101 of the subject is the electrode contact impedance between the subject and the electrode attached to the subject. The operating frequency of the AC excitation source 2 is the frequency of the current supplied by the AC excitation source 2.

[0029] It should be understood that, as described above, in some embodiments, when a measurement electrode group 10 includes two measurement electrodes 1, the AC excitation sources 2 connected to the measurement electrodes 1 of the measurement electrode group 10 have the same operating frequency and amplitude, but opposite phase. In other embodiments, when a measurement electrode group 10 includes two measurement electrodes 1, the operating frequency and amplitude of the AC excitation sources 2 connected to the measurement electrodes 1 of the measurement electrode group 10 may be different. That is, the operating frequencies of the AC excitation sources 2 connected to the measurement electrodes 1 of different measurement electrode groups 10 are different from each other, while the operating frequencies and amplitudes of the AC excitation sources connected to the measurement electrodes 1 of the same measurement electrode group 10 may be the same or different.

[0030] The system 100 further includes an inverting amplifier 5, the input terminal 51 of which is coupled to the at least two measuring electrodes 1, and the output terminal 52 of which is connected to the driving electrode 3. The inverting amplifier 5 is used to invert the voltage of the at least two measuring electrodes 1 and apply it to the skin 101 of the subject through the driving electrode 3, thereby providing a common-mode potential for the multiple measuring electrodes 1.

[0031] Since the skin 101 of the test subject, i.e. human skin, generally has bioelectricity, and its potential is not in the same system potential as that of the system 100, the driving electrode 3 can drive the potential of the system 100 and the skin 101 of the test subject to the same system potential, i.e., the aforementioned common mode potential, after the measuring electrode 1 and the driving electrode 3 come into contact with the skin 101 of the test subject.

[0032] Among them, such as Figure 1 As shown, a resistor R is also connected between the output terminal 52 of the inverting amplifier 5 and the driving electrode 3, and the output terminal 52 of the inverting amplifier 5 is connected to the driving electrode 3 through the resistor R.

[0033] like Figure 1 As shown, the system 100 further includes a computational circuit 6, which is connected between the at least two measuring electrodes 1 and the input terminal 51 of the inverting amplifier 5. The computational circuit 6 is used to calculate the voltage of all measuring electrodes 1 to obtain a computational voltage and output it to the input terminal 51 of the inverting amplifier 5. Specifically, the inverting amplifier 5 is used to invert the computational voltage and apply it to the skin 101 of the subject through the driving electrode 3, thereby providing a common-mode potential for the multiple measuring electrodes 1.

[0034] That is, in some embodiments, the inverting amplifier 5 inverts the voltage of the at least two measuring electrodes 1 by: firstly, performing calculations on the voltage of all measuring electrodes 1 through the operational circuit 6 to obtain an operational voltage, and then the inverting amplifier 5 inverts the operational voltage.

[0035] The operational circuit 6 calculates the average value of the voltages of all measuring electrodes 1 to obtain the operational voltage. This average value calculation may include, but is not limited to, geometric mean calculation and arithmetic mean calculation.

[0036] In this embodiment, the number of the at least two AC excitation sources 2 is equal to the number of the at least two measuring electrodes 1, and the current output terminals 21 of the at least two AC excitation sources 2 are connected to the at least two measuring electrodes 1 in a one-to-one correspondence.

[0037] In each measuring electrode group 10, the measuring electrode 1 receives a current of a corresponding frequency from the current output terminal of the corresponding AC excitation source. A small portion of the current of the corresponding frequency is diverted to other measuring electrode groups 10. During the measurement of the contact impedance of a certain measuring electrode, the controller 4 can acquire a first target voltage of a corresponding frequency in the measuring electrode group 10 and acquire a second target voltage of the same frequency from other measuring electrodes 1 that are not in the same measuring electrode group 10 as the measuring electrode. Then, the contact impedance of the corresponding measuring electrode 1 is obtained based on the first target voltage, the second target voltage, and the current of the corresponding frequency.

[0038] Specifically, the controller 4 can calculate the difference between the first target voltage and the second target voltage, and then divide the difference by the current at the corresponding frequency to obtain the contact impedance of the corresponding measuring electrode 1.

[0039] Among them, such as Figure 1 As shown, in one embodiment, every two measuring electrodes constitute a measuring electrode group 10. The currents generated by the two AC excitation sources 2 connected to the two measuring electrodes 1 in the measuring electrode group 10 have the same magnitude and frequency but opposite phase. Thus, for each measuring electrode group 10 including measuring electrodes 1, the current of the corresponding frequency generated by the corresponding AC excitation source 2 flows into one measuring electrode 1 in the measuring electrode group 10. The current of the corresponding frequency generated by the corresponding AC excitation source 2 flows out from the other measuring electrode 1 in the measuring electrode group 10 after passing through the skin 101 of the subject, while a small portion is diverted to the measuring electrodes in other measuring electrode groups 10. Typically, the current diverted to other measuring electrode groups 10 is extremely small, for example, 1 / 100 of the current generated by the AC excitation source 2, etc. It should be understood that every two measuring electrodes 1 selected for use as the same measuring electrode group 10 in the various embodiments of this application can be two adjacent measuring electrodes or any two non-adjacent measuring electrodes, without particular limitation.

[0040] In other embodiments, each measuring electrode group 10 may include one, three, or other measuring electrodes 1.

[0041] In some embodiments, the controller 4 includes at least two signal input terminals 41, each signal input terminal 41 being coupled to a current output terminal of a corresponding AC excitation source 2 and connected to a corresponding measuring electrode 1. The signal input terminal 41 of the controller 4 is electrically coupled to the measuring electrode 1, the voltage received by the signal input terminal 41 is equal to the voltage of the measuring electrode 1, and the current flowing through the measuring electrode 1 is the current provided by the AC excitation source 2 connected to the measuring electrode 1. The controller 4 can thus receive the voltage of the measuring electrode 1 from the signal input terminal 41, and can also obtain the current provided by the AC excitation source 2 connected to the measuring electrode 1.

[0042] In some embodiments, the current provided by each AC excitation source 2 corresponds to the signal input terminal 41 of the controller 4, and the controller 4 determines the current provided by the AC excitation source 2 connected to each signal input terminal 41 according to the correspondence.

[0043] That is, in this application, the current output terminal 21 of the corresponding AC excitation source 2 coupled to each signal input terminal 41 of the controller 4 can be determined in advance according to the hardware connection relationship. Then, the current provided by the AC excitation source 2 and the signal input terminal 41 are associated to obtain the correspondence. Each signal input terminal 41 of the controller 4 has a unique port number. The current provided by each AC excitation source 2 and the corresponding port number of the signal input terminal 41 can be associated and bound to obtain the correspondence between the current provided by each AC excitation source 2 and the signal input terminal 41 of the controller 4.

[0044] In other embodiments, the system 100 may include a current detection circuit (not shown), through which the controller 4 can detect and acquire the current of each measuring electrode 1.

[0045] That is, in other embodiments, the current of each measuring electrode 1 is directly detected by a current detection circuit.

[0046] In some embodiments, when at least two measuring electrodes 1 are attached to the skin 101 of the subject to measure physiological signals, at least two AC excitation sources 2 simultaneously generate current to the corresponding measuring electrodes 1, thereby realizing the measurement of the contact impedance between each measuring electrode 1 and the skin 101 of the subject.

[0047] However, since at least two AC excitation sources 2 simultaneously generate current to the corresponding measuring electrodes 1, although, as mentioned earlier, for example, two measuring electrodes 1 in the same measuring electrode group 10 form a current loop, and the current mainly flows in from one measuring electrode 1 in the measuring electrode group, passes through the subject's skin 101, and flows out from the other measuring electrode 1 in the measuring electrode group 10, in reality, to a greater or lesser extent, the current generated by each AC excitation source 2 also flows to other measuring electrodes 1 and the drive motor 3. Therefore, the voltage received by each signal input terminal 41 of the controller 4 actually includes multiple voltages generated by the current from multiple AC excitation sources 2 flowing to the measuring electrodes 1, and each of these multiple voltages has the same frequency as the operating frequency of the corresponding AC excitation source 2.

[0048] Therefore, in some embodiments, the controller 4 also filters the voltage collected by each signal input terminal 41 to extract the target voltage with the corresponding frequency.

[0049] Specifically, for any voltage collected at signal input terminal 41, the controller 4 filters the voltage collected at signal input terminal 41 according to the operating frequency of the AC excitation source 2 connected to signal input terminal 41, and extracts a first target voltage with the operating frequency of the AC excitation source 2 connected to signal input terminal 41. Then, based on the extracted first target voltage and the current flowing through the corresponding measuring electrode 1, the contact impedance between the corresponding measuring electrode 1 and the skin 101 of the subject is calculated.

[0050] Wherein, the first target voltage having the operating frequency of the AC excitation source 2 connected to the signal input terminal 41 is the voltage generated by the AC excitation source 2 connected to the signal input terminal 41 flowing through the corresponding measuring electrode. For each measuring electrode connected to the signal input terminal 41, the controller 4 mainly calculates the contact impedance of the measuring electrode connected to the signal input terminal 41 based on the voltage generated by the AC excitation source 2 connected to the signal input terminal 41 flowing through the corresponding measuring electrode and the current provided by the AC excitation source 2 connected to the signal input terminal 41.

[0051] Furthermore, during the measurement of the contact impedance of a certain measuring electrode 1 connected to a certain signal input terminal 41, the controller also acquires a second target voltage that has the same frequency as the current provided by the AC excitation source 2 connected to the certain measuring electrode 1, obtained by filtering the voltage of the signal input terminal 41 connected to other measuring electrodes 1 that are not in the same measuring electrode group 10 as the certain measuring electrode 1.

[0052] In this application, for any voltage collected by signal input terminal 41, the controller 4 is further configured to filter the voltage collected by the signal input terminal 41 again, and extract a second target voltage with a different operating frequency than the AC excitation source 2 connected to the signal input terminal 41. The voltage collected by each signal input terminal 41 can be filtered again to obtain multiple second target voltages. The multiple second target voltages are the voltages generated by other AC excitation sources 2 with other operating frequencies flowing through the measuring electrode 1 connected to the signal input terminal 41.

[0053] Therefore, during the measurement of the contact impedance of a certain measuring electrode 1 connected to a certain signal input terminal 41, the controller can obtain a second target voltage that has the same frequency as the current provided by the AC excitation source 2 connected to the measuring electrode 1, obtained by filtering the signal input terminal 41 of other measuring electrodes 1 that are not in the same measuring electrode group 10 as the measuring electrode 1.

[0054] Specifically, the aforementioned calculation of the contact impedance between the corresponding measuring electrode 1 and the subject's skin 101 based on the extracted first target voltage and the current flowing through the corresponding measuring electrode 1 includes: calculating the contact impedance between the corresponding measuring electrode 1 and the subject's skin 101 based on the extracted first target voltage, second target voltage, and the current flowing through the corresponding measuring electrode 1.

[0055] Specifically, let V1 be the first target voltage obtained by extracting the voltage of a certain signal input terminal, V2 be the second target voltage, and I be the current flowing through the corresponding measuring electrode 1. Then, the contact impedance between the corresponding measuring electrode 1 and the skin 101 of the subject can be calculated according to the formula (V1-V2) / I.

[0056] Specifically, the voltage difference between the first target voltage and the second target voltage is first calculated, and then the ratio of the voltage difference to the current flowing through the corresponding measuring electrode 1 is calculated to obtain the contact impedance between the corresponding measuring electrode 1 and the skin 101 of the subject.

[0057] For example, such as Figure 1As shown, there are four measuring electrodes 1, which are designated as measuring electrodes 1a, 1b, 1c, and 1d. Measuring electrodes 1a and 1b form a measuring electrode group 10, and measuring electrodes 1c and 1d form another measuring electrode group 10. The contact points between the four measuring electrodes 1a, 1b, 1c, and 1d and the skin 101 of the subject are a, b, c, and d, respectively. The signal input terminals 41 of the controller 4 connected to the four measuring electrodes 1a, 1b, 1c, and 1d are signal input terminals 41a, 41b, 41c, and 41d, respectively. The voltages received by the four signal input terminals 41a, 41b, 41c, and 41d are Va, Vb, Vc, and Vd, respectively.

[0058] Suppose that the current supplied by the AC excitation source 2 connected to the four measuring electrodes 1a, 1b, 1c, and 1d is I... ω1 -I ω1 I ω2 and -I ω2 The operating frequencies are ω1, ω1, ω2 and ω2, respectively. That is, measuring electrodes 1a and 1b constitute measuring electrode group 10, and the currents provided by the two AC excitation sources 2 connected to them have the same frequency and opposite phase. Measuring electrodes 1c and 1d also constitute measuring electrode group 10, and the currents provided by the two AC excitation sources 2 connected to them have the same frequency and opposite phase.

[0059] Therefore, for the measurement of the contact impedance between the measuring electrode 1a and the skin 101 of the subject, since the operating frequency of the AC excitation source 2 connected to the measuring electrode 1a is ω1, the supplied current is I. ω1 Therefore, the controller 4 filters the voltage Va received by the signal input terminal 4a connected to the measuring electrode 1a and extracts the voltage Va(ω1) with frequency ω1 as the first target voltage. At this time, for the measuring electrode 1a, the measuring electrodes 1c and 1d are the measuring electrodes in another measuring electrode group 10. At this time, the controller 4 can also obtain the voltage Vc(ω1) or Vd(ω1) with the same frequency as the current provided by the AC excitation source 2 connected to the measuring electrode 1a, obtained by filtering the signal input terminal 41c or 41d connected to the measuring electrode 1c or 1d, as the second target voltage.

[0060] Therefore, the contact impedance Z1 between the measuring electrode 1a and the skin 101 of the subject can be determined based on the voltage Va(ω1), Vc(ω1), and the current I. ω1 It can be calculated, or based on voltage Va(ω1), Vd(ω1) and current I. ω1 The calculation yielded the result.

[0061] That is, the contact resistance Z1 between the measuring electrode 1a and the skin 101 of the subject is Z1 = (Va(ω1) - Vc(ω1)) / Iω1 =(Va(ω1)-Vd(ω1)) / I ω1 .

[0062] Among them, such as Figure 1 As shown, the contact impedance Z1 between the measuring electrode 1a and the skin 101 of the subject is assumed to be equivalent to a resistor, and the AC excitation source 2 connected to the measuring electrode 1a provides I... ω1 After flowing into the measuring electrode 1a, the current mainly flows out from the measuring electrode 1b or the driving electrode 3, but a small amount flows out from the measuring electrodes 1c and 1d and is received by the signal input terminals 41c or 41d. At this time, the I provided by the AC excitation source 2... ω1 The voltage generated at the end where the contact impedance Z1 is connected to the signal input terminal 4a is the voltage Va(ω1), while the voltage I, which flows out from the measuring electrodes 1c and 1d and is received by the signal input terminal 41c or 41d, is... ω1 The current component is very small; therefore, the voltage difference formed by the contact resistance between the measuring electrodes 1c and 1d and the skin 101 of the subject is very small. Therefore, the I provided by the AC excitation source 2... ω1 The voltage generated at the other end of the contact impedance Z1 can be considered equal to the voltage Vc(ω1) or Vd(ω1) obtained by filtering at the signal input terminals 41c or 41d connected to the measuring electrodes 1c or 1d. Therefore, the voltage difference between voltage Va(ω1) and voltage Vc(ω1), or the voltage difference between voltage Va(ω1) and voltage Vd(ω1), can be considered as the voltage difference across the contact impedance Z1 between the measuring electrode 1a and the skin 101 of the subject. Thus, the voltage difference and current I can be calculated using the aforementioned calculation formula. ω1 The contact impedance Z1 can be obtained from the ratio of the two values.

[0063] For example, in measuring the contact impedance between the measuring electrode 1c and the skin 101 of the subject, since the AC excitation source 2 connected to the measuring electrode 1c operates at a frequency of ω2, the supplied current is I. ω,2 Therefore, the controller 4 filters the voltage Vc received by the signal input terminal 4c connected to the measuring electrode 1c, and extracts the voltage Vc(ω2) with a frequency of ω2 as the first target voltage. At this time, for the measuring electrode 1c, the measuring electrodes 1a and 1b are measuring electrodes in another measuring electrode group 10. At this time, the controller 4 can also obtain the voltage Va(ω2) or Vb(ω2) with the same frequency as the current provided by the AC excitation source 2 connected to the measuring electrode 1c, obtained by filtering the signal input terminal 41a or 41b connected to the measuring electrode 1a or 1b, as the second target voltage.

[0064] Therefore, the contact impedance Z3 between the measuring electrode 1c and the skin 101 of the subject can be determined based on the voltage Vc(ω2), Va(ω2), and the current I.ω2 It can be calculated, or based on voltage Vc(ω2), Vb(ω2) and current I. ω2 The calculation yielded the result.

[0065] That is, the contact resistance Z3 between the measuring electrode 1c and the skin 101 of the subject is Z3 = (Vc(ω2) - Va(ω2)) / I ω2 =(Vc(ω2)-Vb(ω2)) / I ω2 .

[0066] For the same reasons mentioned above, the voltage difference between voltage Vc(ω2) and voltage Va(ω2), or the voltage difference between voltage Vc(ω2) and voltage Vb(ω2), can be regarded as the voltage difference across the contact impedance Z3 between the measuring electrode 1c and the skin 101 of the subject. Therefore, the voltage difference and current I can be calculated using the aforementioned formula. ω2 The contact impedance Z3 can be obtained from the ratio of the two values.

[0067] The contact impedance Z2 between measuring electrode 1b and the skin 101 of the subject, and the contact impedance Z4 between measuring electrode 1d and the skin 101 of the subject, can be obtained in the same way as the measurement method of the contact impedance between measuring electrodes 1a and 1c and the skin 101 of the subject, and will not be described in detail here.

[0068] The controller 4 may include multiple filters 44 (such as...) Figure 2 As shown, the plurality of filters 44 are used to filter voltages of different frequencies. For example, the plurality of filters can be multiple bandpass filters, each bandpass filter having a frequency range corresponding to the current frequency of only one AC excitation source 2. Therefore, voltages of other frequencies can be filtered through the bandpass filter to obtain a voltage with the same frequency as the current of the corresponding AC excitation source 2.

[0069] like Figure 2 As shown, the controller 4 further includes an analog-to-digital converter 42 and a processing unit 43. The analog-to-digital converter 42 is connected to both signal input terminals 41 and is used to convert the analog voltage received by the signal input terminals 41 into a digital voltage. The processing unit 43 calculates the contact impedance between the measuring electrode 1 and the skin 101 of the subject based on the digital voltage and the current flowing through the measuring electrode 1. Specifically, the analog-to-digital converter 42 of the controller 4 performs analog-to-digital conversion to obtain a digital voltage, and the processing unit 43 performs the aforementioned functions of the controller 4, such as calculating the contact impedance.

[0070] That is, after the aforementioned signal input terminals 41a, 41b, 41c, and 41d receive voltages Va, Vb, Vc, and Vd in analog form, they are converted into digital form by the analog-to-digital converter 42. Then, the processing unit 43 calculates the contact impedance between each measuring electrode 1 and the skin 101 of the subject using the aforementioned calculation method.

[0071] The analog-to-digital converter 42 can be a single unit, including multiple inputs and multiple outputs corresponding one-to-one with the inputs. Each input is connected to a corresponding signal input terminal 41, and each output is connected to a corresponding pin of the processing unit 43. The pins of the processing unit 43 correspond one-to-one with the signal input terminals 41 through the inputs and outputs of the analog-to-digital converter 42. Therefore, when the pins of the processing unit 43 receive a voltage, they can identify which signal input terminal is collecting the voltage. Thus, based on the aforementioned correspondence between the current provided by the AC excitation source 2 and the signal input terminal 41, the current flowing through the corresponding measuring electrode 1 can be determined.

[0072] In other embodiments, the analog-to-digital converter 42 may be a component independent of the controller 4. For example, the analog-to-digital converter 42 may be connected between each measuring electrode 1, driving electrode 3 and the signal input terminal 41 of the controller 4. The signal input terminal 41 of the controller 4 receives the digital form of voltage obtained by the analog-to-digital converter 42 after analog-to-digital conversion.

[0073] When the analog-to-digital converter 42 is a component independent of the controller 4, it can be a single converter including multiple inputs and multiple outputs corresponding one-to-one with each input. Each input is connected to a measuring electrode 1 or a driving electrode 3, and each output is connected to the signal input terminal 41 of the controller 4. Thus, the signal input terminal 41 can correspond one-to-one with the measuring electrode 1 and its connected AC excitation source 2, or with the driving electrode 3, through the inputs and outputs of the analog-to-digital converter 42. Therefore, a one-to-one correspondence still exists between the signal input terminal 41 and the AC excitation source 2, forming the aforementioned correspondence between the current provided by the AC excitation source 2 and the signal input terminal 41.

[0074] Obviously, in other embodiments, there may be multiple analog-to-digital converters 42. Regardless of whether the analog-to-digital converters 42 are integrated into the controller 4, each signal input terminal 41 can be connected to an analog-to-digital converter 42 and perform analog-to-digital conversion independently.

[0075] Please see Figure 2 This is an internal module architecture diagram of the controller 4 in one embodiment. When the controller 4 includes multiple filters 44, the multiple filters 44 may be located between the analog-to-digital converter 42 and the processing unit 43.

[0076] The analog-to-digital converter 42 is described as having one input, including multiple inputs 421 and outputs 422 corresponding to each input. The analog-to-digital converter 42 is used to convert the voltage at a corresponding measurement electrode 1 received from each input into a digital form, and then send it to the processing unit 43 for calculation. Each output 422 of the analog-to-digital converter 42 and the processing unit 43 may include the multiple filters to achieve the extraction of voltages at multiple frequencies.

[0077] In some embodiments, multiple filters 44 are connected in parallel between an output 422 of the analog-to-digital converter 42 and the processing unit 43, and each filter 44 is also connected in series with a switch 45. The multiple parallel filters 44 and the switches 45 connected in series with the filters 44 form a filter group 440. Each output 422 of the analog-to-digital converter 42 and the processing unit 43 are provided with the filter group 440. The processing unit 43 is connected to the switch 45 of each filter group 440. By controlling the corresponding switch 45 to be turned on, the corresponding filter 44 is enabled and filtered, thereby extracting the voltage of the corresponding frequency.

[0078] For example, when it is necessary to filter the voltage received at signal input terminal 41a to obtain a voltage with frequency ω1, the switch 45 connected to the filter 44 of the filter bank 440 coupled to the signal input terminal 41a for filtering voltages other than the frequency ω1 can be turned on, while the switch 45 connected to the other filter 44 coupled to the signal input terminal 41a can be turned off. Thus, the voltage received at the signal input terminal 41a is filtered by the filter 44 for filtering voltages other than the frequency ω1, filtering out voltages of other frequencies and leaving only the voltage with frequency ω1, thereby extracting the voltage V(ω1) with frequency ω1.

[0079] The filter bank 440 coupled to the signal input terminal 41a refers to the output 422 of the analog-to-digital converter 42 to which the filter bank 440 is connected, which corresponds to the input connected to the signal input terminal 41a. It should be understood that the filter bank 440 shown in the figure is a hardware implementation. In some other embodiments, the hardware-implemented filter bank can be omitted, and the filtering function can be implemented in software. That is, in other embodiments, a software filter can be integrated into the controller 4 to implement the above-mentioned filtering function.

[0080] The switch 45 can be a switching transistor such as MOSFET, BJT, or IGBT.

[0081] like Figure 1As shown, the system 100 further includes at least two signal buffers 7, each signal buffer 7 being connected between a signal input terminal 41 of the controller 4 and the corresponding AC excitation source 2 / measuring electrode 1. The signal buffer 7 is used to buffer the voltage at the measuring electrode 1. As mentioned above, the signal input terminal 41 of the controller 4 obtains the voltage at the measuring electrode 1 through electrical coupling.

[0082] In some embodiments, a signal buffer 7 is also connected between the driving electrode 3 and the corresponding signal input terminal 41 of the controller 4. The signal buffer 7 connected between the driving electrode 3 and the corresponding signal input terminal 41 is used to isolate the voltage at the driving electrode 3. The signal input terminal 41 of the controller 4 obtains the voltage at the driving electrode 3 through electrical coupling.

[0083] When the analog-to-digital converter 42 is a component independent of the controller 4, each signal buffer 7 may be located between each measuring electrode 1 or driving electrode 3 and the analog-to-digital converter 42.

[0084] In some embodiments, the controller 4 is further configured to control the output of an alarm signal to trigger an alarm when the calculated contact impedance between any of the measuring electrodes 1 and the skin 101 of the subject exceeds a preset threshold.

[0085] That is, the controller 4 also compares the calculated contact impedance between any measuring electrode 1 and the skin 101 of the subject with the preset threshold, and when the contact impedance exceeds the preset threshold, it controls the output of an alarm signal to provide an alarm prompt.

[0086] The preset threshold is defined as the threshold at which the quality of physiological signals will exceed the allowable value when the contact impedance exceeds this value.

[0087] In some embodiments, the alarm signal includes at least one of text, pattern, and video. The controller 4 is also connected to a display 200. When the calculated contact impedance between any measuring electrode and the skin 101 of the subject exceeds a preset threshold, the controller 4 controls the display 200 to display the alarm signal.

[0088] The alarm signal can specifically indicate which measuring electrode is malfunctioning. For example, the alarm signal can be a text message stating "The contact impedance of measuring electrode XX is abnormal, please check," or it can be a pattern including several measuring electrodes 1, where the measuring electrode whose release resistance exceeds a preset threshold is prominently displayed, for example, by highlighting it or marking it with a conspicuous color, such as red or yellow. When the alarm signal is a video, the location of the measuring electrode 1 exceeding the preset threshold can also be displayed via video, while simultaneously providing an audio announcement, such as "The contact impedance of measuring electrode XX is abnormal, please check."

[0089] The display 200 can be a standalone display or an electronic device with a screen, such as a mobile phone, tablet computer, or laptop computer. The display 200 can be connected to the controller 4 via wired or wireless means, and can receive and display alarm signals sent by the controller 4.

[0090] The display 200 may be a component independent of the system 100; for example, a user may temporarily connect to the display 200. Obviously, the display 200 may also be a component included in the system 100. For example, at least two AC excitation sources 2, drive electrodes 3, controller 4, inverting amplifier 5, and operational circuit 6 of the system 100 may be integrated into a single device, and the display 200 may serve as the display screen of that device.

[0091] In some embodiments, the system 100 further includes an alarm circuit 8, which is used to output an audible and visual alarm signal. When the calculated contact impedance between any measuring electrode and the skin 101 of the subject exceeds a preset threshold, the controller 4 controls the alarm circuit 8 to output an audible and visual alarm signal.

[0092] The audible and visual alarm signal includes at least one of a light signal and a sound signal. The alarm circuit 8 may include at least one of an LED light, a speaker, or other structures, and can output the audible and visual alarm signal. Specifically, the audible and visual alarm signal may be at least one of the following: a flashing light signal, a light signal that is constantly lit in a specific color, a continuously emitted beeping sound, or a sound signal with voice content such as "The contact impedance of the XX measuring electrode is abnormal, please check".

[0093] Therefore, by outputting an alarm signal, users can be promptly reminded, such as medical staff, to check whether the contact of measuring electrode 1 is intact, and to promptly reattach measuring electrode 1 with poor contact, so as to avoid affecting the measurement of physiological parameters.

[0094] Obviously, in some embodiments, the controller 4 may not need to compare the contact impedance with the preset threshold, and the alarm circuit may not be required. The controller 4 can directly output the contact impedance, so that medical staff can judge whether there is an abnormality based on the contact impedance.

[0095] In some embodiments, the system 100 may further include a memory 9, in which the correspondence between the current provided by each of the aforementioned AC excitation sources 2 and the signal input terminal 41 of the controller 4 can be stored. The memory 9 may be an SD card, a solid-state memory, etc.

[0096] The controller 4 can be a central processing unit (CPU), a microcontroller, a digital signal processor (DSP), etc. Specifically, when the controller 4 includes a digital-to-analog converter (DAC) 42 and a processing unit 43, the controller 4 can be a CPU, a microcontroller, a DSP, etc., with integrated analog-to-digital conversion circuitry; the processing unit 43 is the processing circuitry portion of the controller 4. When the DAC 42 is located outside the processing unit 43, the processing unit 43 can be a CPU, a microcontroller, a DSP, etc.

[0097] Please see Figures 4-5 This is a schematic diagram showing the measurement signal waveform and contact impedance indication in one embodiment of this application. The controller 4 is connected to the aforementioned display 200, and the controller 4 is also used to control the display 200 to display the physiological signal waveform measured by the measuring electrodes and the contact impedance indication of the measuring electrodes. The contact impedance indication is used to indicate the magnitude of the contact impedance of the corresponding measuring electrode. Figure 1 In the system 100 of the illustrated embodiment, there are four measuring electrodes 1a-1b. Typically, any two or more electrodes can be used to jointly measure one physiological signal waveform. For example, measuring electrodes 1a and 1b measure a first physiological signal waveform, denoted as S1-2, and measuring electrodes 1c and 1d measure a second physiological signal waveform, denoted as S3-4. In other embodiments, measuring electrode 1d can be used as a common terminal, and measuring electrodes 1a, 1b, and 1c can be used together with measuring electrode 1d as the common terminal to jointly measure three physiological signal waveforms (not shown).

[0098] Near each physiological signal waveform, the contact impedance between each measuring electrode and human skin can be displayed accordingly, such as... Figure 4 As shown; it can also correspondingly display the common contact impedance between the two or more electrodes used to measure the physiological waveform signal and the human skin, such as Figure 5 As shown. Specifically, as Figure 4As shown, below the physiological signal waveform S1-2 jointly measured by measuring electrodes 1a and 1b, the contact impedance indicators J1 and J2 of each measuring electrode 1a and 1b with human skin, corresponding to the physiological signal waveform S1-2, are displayed respectively. The physiological signal waveform S3-4 is measured by measuring electrodes 1c and 1d, and the contact impedance indicators J3 and J4 of each measuring electrode 1c and 1d with human skin, corresponding to this physiological signal waveform, are displayed below it. The physiological signal waveform S1-2, the corresponding contact impedance indicators J1 and J2, the physiological signal waveform S3-4, and the corresponding contact impedance indicators J3 and J4 are arranged sequentially. The interval between the contact impedance indicators J1 and J2 and the physiological signal waveform S1-2 is smaller than the interval between the contact impedance indicators J1 and J2 and the physiological signal waveform S3-4. That is, in some embodiments, the interval between the contact impedance indicators J1 and J2 and the corresponding physiological signal waveform S1-2 is smaller than the interval between the contact impedance indicators J1 and J2 and other physiological signal waveforms S3-4 measured by other measuring electrodes. Obviously, the controller 4 can control the display 200 to display the physiological signal waveforms measured by all measuring electrodes and the corresponding contact impedance indications.

[0099] The contact impedance indicators J1 and J2 can be displayed below the corresponding physiological signal waveforms S1-2.

[0100] The contact impedance indicators J1 and J2 continuously indicate the magnitude of the contact impedance of the corresponding measuring electrodes 1a and 1b throughout the duration of the physiological signal waveform S1-2. Specifically, the contact impedance indicator J1 is used to indicate the contact impedance of the measuring electrodes 1a and 1b used to measure the physiological signal waveform S1-2 at various times, thereby further indicating the signal quality of the physiological signal waveform S1-2 at the corresponding times.

[0101] When the contact impedance is too high, it indicates poor contact or detachment of measuring electrodes 1a and / or 1b. Therefore, the signal quality is poor, meaning the acquired physiological signal may have excessive noise interference and low reliability. Conversely, when the contact impedance is low, it indicates good contact between measuring electrodes 1a and / or 1b. Therefore, the signal quality is good, meaning the acquired physiological signal will not be mixed with other interference signals due to poor contact, and its reliability is high. Therefore, by using the contact impedance indicators J1 and J2 to indicate the contact impedance at each moment, the signal quality of the physiological signal waveform S1-2 at the corresponding moment can be reflected.

[0102] The impedance display of measuring electrodes 1c and 1d is similar to that of measuring electrodes 1a and 1b, and will not be repeated here.

[0103] Since a physiological signal is obtained by measuring at least two electrodes, the quality of that physiological signal is determined by both electrodes. Therefore, in some embodiments, it is not necessary to display the individual contact impedance between each electrode and the skin separately; instead, the "combined impedance" of the two electrodes and the skin can be displayed, i.e., the combined contact impedance of the equivalent electrodes 1a and 1b with the skin. For example, in... Figure 5 In the illustrated embodiment, the common contact impedance value J1-2 between the measuring electrodes 1a and 1b for measuring the physiological signal and the skin is displayed below the physiological signal waveform S1-2; the common contact impedance value J3-4 between the measuring electrodes 1c and 1d for measuring the physiological signal is displayed below the physiological signal waveform S3-4.

[0104] The physiological signals measured by the measuring electrodes include at least one of electrocardiogram (ECG), electroencephalogram (EEG), and electromyography (EMG).

[0105] That is, the measuring electrode can be an electrode pad that is attached to the skin of the human chest to measure electrocardiogram signals, or an electrode pad that is attached to the head to measure electroencephalogram signals, or an electrode pad that is attached to the skin of the muscle to be tested to measure electromyogram signals.

[0106] In some embodiments, the contact impedance indicator includes at least one of color and pattern, and the contact impedance indicator varies depending on the impedance range in which the magnitude of the contact impedance falls.

[0107] That is, in some embodiments, the contact impedance indicator may be a color indicator, with different colors indicating different levels of contact impedance; or, the contact impedance indicator may be a pattern, with different patterns indicating different levels of contact impedance. The different patterns may include patterns with different content, patterns with different shapes, and so on. In some embodiments, the contact impedance indicator may be a combination of pattern and color, with different patterns and colors indicating different levels of contact impedance.

[0108] In some embodiments, the impedance range includes a first impedance range, a second impedance range, and a third impedance range. The first impedance range, the second impedance range, and the third impedance range can be set according to the contact impedance range corresponding to good contact, poor contact, and complete detachment of the measuring electrode, respectively. The first impedance range is smaller than the second impedance range, and the second impedance range is smaller than the third impedance range.

[0109] That is, the first impedance range is the range of contact impedance of the measuring electrode when the measuring electrode is in good contact, the second impedance range is the range of contact impedance of the measuring electrode when the measuring electrode is in contact but not in good contact, and the third impedance range is the range of contact impedance of the measuring electrode when the measuring electrode is completely detached.

[0110] The controller 4 can calculate the contact impedance between one or more measuring electrodes and the skin 101 of the subject at various times, determine the corresponding contact impedance indication based on the impedance range of the contact impedance calculated at each time, and then control the display 200 to display the physiological signal waveform measured by the measuring electrodes and the determined corresponding contact impedance indication.

[0111] For example, such as Figure 4 As shown in this application, the contact impedance indicator J1 can be a color indicator. When the controller 4 determines that the contact impedance of the measuring electrode 1a is within a first impedance range at a certain moment or within a certain period of time, it controls the contact impedance indicator J1 to display a first color Y1. When the controller 4 determines that the contact impedance of the measuring electrode 1a is within a second impedance range at a certain moment or within a certain period of time, it controls the contact impedance indicator J1 to display a second color Y2. And when the controller 4 determines that the contact impedance of the measuring electrode 1a is within a third impedance range at a certain moment or within a certain period of time, it controls the contact impedance indicator J1 to display a third color Y3.

[0112] In this embodiment, the first color Y1 can be green, the second color Y2 can be yellow, and the third color Y3 can be red. Obviously, in other embodiments, the first color Y1, the second color Y2, and the third color Y3 can be other colors.

[0113] Obviously, in other embodiments, the contact impedance indicator J1 can be a pattern indicator, for example, a pattern indicator of different shapes. Specifically, when the controller 4 determines that the contact impedance of the measuring electrode 1a is within a first impedance range at a certain moment or within a certain period of time, it controls the contact impedance indicator J1 to be a straight line; when the controller 4 determines that the contact impedance of the measuring electrode 1a is within a second impedance range at a certain moment or within a certain period of time, it controls the contact impedance indicator J1 to be a wave shape; and when the controller 4 determines that the contact impedance of the measuring electrode 1a is within a third impedance range at a certain moment or within a certain period of time, it controls the contact impedance indicator J1 to be a sawtooth wave shape, and so on.

[0114] Therefore, in this application, the controller 4 can control the display 200 to display the physiological signal waveforms measured by each measuring electrode, and can also synchronously display the contact impedance indicator corresponding to the measuring electrode to indicate the magnitude of the contact impedance of each measuring electrode at each time, thereby reflecting the signal quality of the corresponding physiological signal waveform at each time. This provides a reference for subsequent analysis of the physiological signal; for example, when the contact impedance is high and the signal quality is poor, that segment of the physiological signal waveform should be discarded and not analyzed. Alternatively, the contact impedance indicator can also prompt medical personnel to check the contact status of the corresponding measuring electrode 1, and reattach any measuring electrodes that have fallen off or have poor contact.

[0115] Please see Figure 6 This is a schematic diagram of a system for measuring electrode contact impedance according to another embodiment of this application. In other embodiments, the system 100 may also include at least one measuring electrode 1, at least one AC excitation source 2, a driving electrode 3, and a controller 4. The at least one measuring electrode 1 is used to connect to the skin 101 of the subject to measure physiological parameters, wherein the at least one measuring electrode 1 forms at least one measuring electrode group 10. Each AC excitation source 2 includes an AC output terminal 21, and the at least one AC excitation source 2 is respectively connected to the at least one measuring electrode 1, that is, the current output terminal 21 of the at least one AC excitation source is respectively connected to each measuring electrode in the at least one measuring electrode group 10, wherein the operating frequencies of the AC excitation sources 2 connected to the measuring electrodes 1 of different measuring electrode groups 10 are different. The driving electrode 3 is used to connect to the skin 101 of the subject and provide a common-mode potential for the plurality of measuring electrodes 1. The controller 4 is coupled to the current output terminal 21 of each AC excitation source 2 and each measuring electrode 1, and is used to acquire the voltage and current at each measuring electrode 1, and calculate the contact impedance between each measuring electrode 1 and the skin 101 of the subject based on the voltage and current at each measuring electrode 1.

[0116] That is, in some other embodiments, the system 100 may include at least one measuring electrode group 10, and when physiological signals are measured by one measuring electrode group 1, the contact impedance of each measuring electrode 1 is also measured.

[0117] The number of the at least one measuring electrode 1 can be odd or even, and every two measuring electrodes 1 form a pair to constitute a measuring electrode group 10.

[0118] When the number of the at least one measuring electrode 1 is even, every two measuring electrodes 1 form a pair to constitute a measuring electrode group 10, so that the at least one measuring electrode 1 can be paired in pairs to form several measuring electrode groups. The same measuring electrode group 10 can form a current loop on its own for measuring contact impedance.

[0119] Among them, such as Figure 6 The number of the at least one measuring electrode 1 can be odd. When the number of the at least one measuring electrode 1 is odd, in addition to each pair of measuring electrodes 1 forming a measuring electrode group 10, and each measuring electrode group 10 forming a current loop L1 independently, the remaining independent measuring electrode 1 forms a separate measuring electrode group 10 and forms a loop L2 with the driving electrode 3. For a measuring electrode group 10 including two measuring electrodes 1, current flows in from one measuring electrode 1 in the measuring electrode group 10, passes through the skin 101 of the subject, and flows out from the other measuring electrode 1 in the measuring electrode group 10. For the remaining independent measuring electrode 1, current flows in from the independent measuring electrode 1, passes through the skin 101 of the subject, and flows out from the driving electrode 3.

[0120] That is, in another embodiment, when the number of the at least one measuring electrode 1 is odd, after every two measuring electrodes 1 form a pair to constitute a measuring electrode group 10, there will be one extra measuring electrode 1. This extra measuring electrode 1 can form a current loop L2 with the driving electrode 3 to measure the contact impedance at the measuring electrode 1. Therefore, when the number of the at least one measuring electrode 1 is odd, the driving electrode 3, in addition to providing the common-mode potential, is also used to form a current loop with the extra measuring electrode 1 to measure the contact impedance at the measuring electrode 1.

[0121] When the number of the at least one measuring electrode 1 is one, the one measuring electrode 1 can form a current loop L2 with the driving electrode 3 to realize the measurement of the contact impedance at the measuring electrode 1. Therefore, even if there is only one measuring electrode 1, the contact impedance at the measuring electrode 1 can be measured.

[0122] Therefore, regardless of whether the number of measuring electrodes 1 is odd or even, accurate measurement of the contact impedance between each measuring electrode 1 and the skin 101 of the subject can be achieved.

[0123] In some embodiments, when one measuring electrode 1 in a measuring electrode group 10 has poor contact with the skin 101 of the subject, another measuring electrode 1 in the measuring electrode group 10 forms a circuit with the driving electrode 3, and current flows in from the other measuring electrode 1, passes through the skin 101 of the subject, and flows out from the driving electrode 3.

[0124] That is, in some embodiments, when two measuring electrodes 1 constitute a measuring electrode group 10, and one measuring electrode 1 experiences a poor contact or other abnormality, making it impossible to form a current loop with the other measuring electrode 1 in the measuring electrode group 10, the other measuring electrode 1 with better contact can form a loop with the driving electrode 3. Current flows in from the other measuring electrode 1, passes through the subject's skin 101, and flows out from the driving electrode 3. In this case, the contact impedance between the measuring electrode 1 and the subject's skin 101 can still be measured.

[0125] In some embodiments, when there is an abnormal measuring electrode 1 in multiple measuring electrode groups 10 that cannot form a current loop with another measuring electrode 1 in the same measuring electrode group 10, the other measuring electrode 1 in multiple measuring electrode groups 10 can each form a loop with the driving electrode 3, and the measurement of the contact impedance between the measuring electrode 1 that has not malfunctioned and the subject's skin 101 can still be guaranteed.

[0126] As mentioned above, the AC excitation sources 2 connected to the measuring electrodes 1 of different measuring electrode groups 10 have different operating frequencies. Therefore, even if another measuring electrode 1 in multiple measuring electrode groups 10 forms a circuit with the driving electrode 3, and the current flows from each other measuring electrode 1 through the skin 101 of the subject and then flows out from the driving electrode 3, they can be distinguished one by one without interfering with each other because the frequency of the current flowing through each measuring electrode 1 and the driving electrode 3 is different.

[0127] like Figure 6 As shown, the driving electrode 3 is also coupled to a signal input terminal 41 of the controller 4. Figure 6 As shown, let e be the contact position between the driving electrode 3 and the skin 101 of the test subject, and let 41 be the signal input terminal 41 of the controller 4 coupled to the driving electrode 3. In this case, a small amount of current provided by each AC excitation source 2 will also flow to the driving electrode 3, and after passing through the contact impedance Z5 between the driving electrode 3 and the skin 101 of the test subject, a voltage Ve will be formed and received by the signal input terminal 41e coupled to the driving electrode 3.

[0128] The aforementioned second target voltage can also be a voltage obtained by filtering the voltage of the signal input terminal 41 connected to the driving electrode 3, and having the same frequency as the current provided by the AC excitation source 2 connected to the measuring electrode 1.

[0129] That is, during the measurement of the contact impedance of a certain measuring electrode 1 connected to a certain signal input terminal 41, the controller 4 may also obtain a second target voltage that has the same frequency as the current provided by the AC excitation source 2 connected to the certain measuring electrode 1, obtained by filtering the voltage of other measuring electrodes 1 or driving electrodes 3 connected to the signal input terminal 41 that are not in the same measuring electrode group 10 as the certain measuring electrode 1.

[0130] For example, for measuring the contact impedance between the measuring electrode 1a and the skin 101 of the subject, the controller 4 can also obtain the voltage Ve(ω1) filtered from the signal input terminal 412 connected to the drive electrode 3, which has the same frequency as the current provided by the AC excitation source 2 connected to the measuring electrode 1a, as the second target voltage.

[0131] Therefore, the contact impedance Z1 between the measuring electrode 1a and the skin 101 of the subject can also be determined based on the voltage Va(ω1), Ve(ω1), and the current I. ω1 The calculation yielded the result.

[0132] That is, the contact resistance Z1 between the measuring electrode 1a and the skin 101 of the subject is Z1 = (Va(ω1) - Vc(ω1)) / I ω1 =(Va(ω1)-Vd(ω1)) / I ω1 =(Va(ω1)-Ve(ω1)) / I ω1 .

[0133] For measuring the contact impedance between the measuring electrode 1c and the skin 101 of the subject, the controller 4 can also obtain the voltage Ve(ω2) obtained by filtering in the signal input terminal 412 connected to the drive electrode 3, which has the same frequency as the current provided by the AC excitation source 2 connected to the measuring electrode 1a, as the second target voltage.

[0134] Therefore, the contact impedance Z3 between the measuring electrode 1c and the skin 101 of the subject can also be determined based on the voltage Vc(ω2), Ve(ω2), and the current I. ω2 The calculation yielded the result.

[0135] That is, the contact resistance Z3 between the measuring electrode 1c and the skin 101 of the subject can also be equal to (Vc(ω2)-Ve(ω2)) / I ω2 .

[0136] Therefore, the driving electrode 3 can also be used as an auxiliary electrode to measure the contact impedance between each measuring electrode 1 and the skin 101 of the subject, thereby realizing the measurement of the contact impedance between each measuring electrode 1 and the skin 101 of the subject.

[0137] in, Figure 6 The system 100 shown is Figure 1The main difference of the system 100 shown is that the driving electrode 3 can also be used as an auxiliary electrode to measure the contact impedance between each measuring electrode 1 and the skin 101 of the subject, thereby realizing the measurement of the contact impedance between each measuring electrode 1 and the skin 101 of the subject. Thus, even when there is only one measuring electrode group 10 or when a measuring electrode 1 in a certain measuring electrode group 10 has poor contact or falls off, the contact impedance measurement can still be realized.

[0138] in, Figure 6 The specific structure or function of the components included in the system 100 shown can be found in the foregoing descriptions, for example, as... Figure 2 As shown, the controller 4 may include multiple filters 44, which are used to filter voltages of different frequencies. For example, these multiple filters may be multiple bandpass filters, each bandpass filter having a frequency range corresponding to the current frequency of only one AC excitation source 2. Therefore, voltages of other frequencies can be filtered through these bandpass filters to obtain a voltage with the same frequency as the current of the corresponding AC excitation source 2. As another example, the controller 4 may also include an analog-to-digital converter 42 and a processing unit 43. The analog-to-digital converter 42 is connected to at least one signal input terminal 41 and is used to convert the analog voltage received by the signal input terminal 41 into a digital voltage. The processing unit 43 calculates the contact impedance between the measuring electrode 1 and the skin 101 of the subject based on the digital voltage and the current flowing through the measuring electrode 1, and so on.

[0139] For a more detailed description, please refer to the preceding description, which will not be repeated here.

[0140] Please see Figure 3 The diagram shows a monitoring device 300 module. In some embodiments, the monitoring device 300 may include the aforementioned system 100. Therefore, the monitoring device 300 can simultaneously monitor the contact impedance between each measuring electrode and the skin of the human body while measuring human physiological signals, thereby providing an effective reference for the quality of physiological signals.

[0141] In other embodiments, the components of the system 100 may be partially located within the monitoring device 300 and partially independent of the monitoring device 300. For example, the controller 4 may be located within the monitoring device 300, while the measuring electrode 1, the AC excitation source 2, etc., may be located outside the monitoring device 300.

[0142] The monitoring device 300 may be a bedside monitor, a wearable monitor, a handheld monitor, etc.

[0143] The monitoring device 300 further includes a monitoring component 301, which is connected to the plurality of measuring electrodes 1 and is used to acquire physiological signals through the measuring electrodes 1 for monitoring physiological signs. While the monitoring component 301 acquires physiological signals through the measuring electrodes 1 for monitoring physiological signs, the system 100 can simultaneously measure the contact impedance between the measuring electrodes 1 and the skin 101 of the subject, providing a reference for the quality of the physiological signals.

[0144] Please see Figure 7 This is a flowchart of an impedance measurement method according to an embodiment of this application. The method can be applied to the aforementioned system 100, and the method includes:

[0145] At least two measuring electrodes are respectively connected to the skin of the subject, wherein the plurality of measuring electrodes form at least two measuring electrode groups (S601).

[0146] At least two AC excitation sources provide current to the at least two measuring electrodes respectively, wherein the current output terminals of the at least two AC excitation sources are respectively connected to each measuring electrode in the measuring electrode group, and the operating frequencies of the AC excitation sources connected to the measuring electrodes of different measuring electrode groups are different (S603).

[0147] The voltage and current at each measuring electrode are obtained, and the contact impedance between each measuring electrode and the subject's skin is calculated based on the voltage and current at each measuring electrode (S605).

[0148] In some embodiments, the number of the at least two AC excitation sources is equal to the number of the at least two measuring electrodes, and the current output terminals of the at least two AC excitation sources are connected one-to-one with the at least two measuring electrodes. In some embodiments, acquiring the voltage and current at each measuring electrode and calculating the contact impedance between each measuring electrode and the subject's skin based on the voltage and current at each measuring electrode may include: during the measurement of the contact impedance of a certain measuring electrode, acquiring a first target voltage with a corresponding frequency in the certain measuring electrode group and acquiring a second target voltage with the same frequency from other measuring electrodes not in the same measuring electrode group as the certain measuring electrode, and then deriving the contact impedance of the corresponding measuring electrode based on the first target voltage, the second target voltage, and the current with the corresponding frequency.

[0149] In some embodiments, each measuring electrode is connected to a corresponding signal input terminal of the controller and coupled to a current output terminal of a corresponding AC excitation source. The signal input terminal of the controller is electrically coupled to the measuring electrode. The voltage acquired / received by the signal input terminal is equal to the voltage of the measuring electrode, and the current provided by the AC excitation source to the corresponding measuring electrode is the current flowing through the corresponding measuring electrode, i.e., the current at the measuring electrode. Acquiring the voltage and current at each measuring electrode may include:

[0150] The voltage at the corresponding measuring electrode is obtained by acquiring the voltage from the signal input terminal of the controller, and the current at the measuring electrode is obtained by acquiring the current provided by the AC excitation source connected to the corresponding measuring electrode.

[0151] Furthermore, the step of obtaining the current at the measuring electrode by acquiring the current provided by the AC excitation source connected to the corresponding measuring electrode may include: determining the current provided by the AC excitation source connected to each signal input terminal based on the correspondence between the current provided by each AC excitation source and the signal input terminal of the controller.

[0152] In some embodiments, the method may further include: during the measurement of the contact impedance of a measuring electrode connected to a signal input terminal, the controller filters the voltage acquired at the signal input terminal according to the operating frequency of the AC excitation source connected to the signal input terminal, and extracts a first target voltage having the operating frequency of the AC excitation source connected to the signal input terminal; the controller also acquires a second target voltage obtained by filtering the voltage of the signal input terminal connected to other measuring electrodes or driving electrodes not in the same measuring electrode group as the measuring electrode, which has the same frequency as the current provided by the AC excitation source connected to the measuring electrode.

[0153] The aforementioned method of deriving the contact impedance of the corresponding measuring electrode based on the first target voltage, the second target voltage, and the current at the corresponding frequency may specifically include: calculating the contact impedance between the corresponding measuring electrode and the skin of the subject based on the extracted first target voltage, the second target voltage, and the current flowing through the corresponding measuring electrode.

[0154] Specifically, the step of calculating the contact impedance between the corresponding measuring electrode and the skin of the subject based on the extracted first target voltage, second target voltage, and current flowing through the corresponding measuring electrode may further include: first calculating the voltage difference between the first target voltage and the second target voltage, and then calculating the ratio of the voltage difference to the current flowing through the corresponding measuring electrode to obtain the contact impedance between the corresponding measuring electrode and the skin of the subject.

[0155] In some embodiments, the method may further include: controlling a display to show the physiological signal waveforms measured by the measuring electrodes and a contact impedance indication for each measuring electrode, the contact impedance indication being used to indicate the magnitude of the contact impedance of the corresponding measuring electrode in real time.

[0156] The contact impedance indicator includes at least one of color and pattern, and the contact impedance indicator varies depending on the impedance range in which the magnitude of the contact impedance falls.

[0157] Each physiological signal waveform is displayed adjacent to its corresponding contact impedance indicator. The contact impedance indicator may be displayed below the corresponding physiological signal waveform. The display of the contact impedance indicator has been described in detail above and will not be repeated here.

[0158] Please see Figure 8 This is a flowchart of an impedance measurement method according to an embodiment of this application. The method can be applied to the aforementioned system 100, and the method includes:

[0159] At least two measuring electrodes are respectively connected to the skin of the subject, wherein the plurality of measuring electrodes form at least two measuring electrode groups (S701).

[0160] At least two AC excitation sources provide current to the at least two measuring electrodes respectively, wherein the current output terminals of the at least two AC excitation sources are respectively connected to each measuring electrode in the measuring electrode group, and the operating frequencies of the AC excitation sources connected to the measuring electrodes of different measuring electrode groups are different (S703).

[0161] The voltage and current at each measuring electrode are obtained, and the contact impedance between each measuring electrode and the subject's skin is calculated based on the voltage and current at each measuring electrode (S705).

[0162] When the calculated contact impedance between any measuring electrode and the subject's skin exceeds a preset threshold, an alarm signal is output to trigger an alarm (S707).

[0163] The alarm signal may include at least one of text, pattern, and video. Step S705 may include: when the calculated contact impedance between any measuring electrode and the skin of the subject exceeds a preset threshold, controlling the display to show the alarm signal.

[0164] In another embodiment, the alarm signal may be an audible and visual alarm signal, including at least one of a light signal and a sound signal. Step S705 may include: when the calculated contact impedance between any measuring electrode and the skin of the subject exceeds a preset threshold, controlling an alarm circuit to output an audible and visual alarm signal, wherein the alarm circuit may include at least one of the following structures: an LED light, a speaker, etc.

[0165] Among them, steps S701 to S705 and Figure 7 Steps S601 to S605 in the method shown correspond to [specific steps / methods], and a more detailed description can be found in [reference / document]. Figure 7 The relevant descriptions of steps S601 to 605 are not repeated here.

[0166] Furthermore, the Figure 8 The impedance measurement method in another embodiment of this application may also include the aforementioned additional method steps or more specific steps. For example, the method may further include: controlling a display to show the physiological signal waveform measured by each measuring electrode and the contact impedance indication of each measuring electrode, wherein the contact impedance indication is used to indicate the magnitude of the contact impedance of the corresponding measuring electrode in real time. The contact impedance indication includes at least one of color and pattern, and the contact impedance indication varies depending on the impedance range in which the magnitude of the contact impedance falls.

[0167] Please see Figure 9 This is a flowchart of an impedance measurement method in another embodiment of this application. The method can be applied to the aforementioned system 100, for example... Figure 3 In the system 100 shown, the method includes:

[0168] At least one measuring electrode is connected to the skin of the subject, wherein the at least one measuring electrode forms at least one measuring electrode group (S801).

[0169] At least one AC excitation source provides current to the at least one measuring electrode, wherein the current output terminal of the at least one AC excitation source is connected to each measuring electrode in the measuring electrode group, and the operating frequency of the AC excitation source connected to the measuring electrodes of different measuring electrode groups is different (S803).

[0170] In some embodiments, the number of the at least one AC excitation source is equal to the number of the at least one measuring electrode, and the current output terminal of the at least one AC excitation source is connected to the at least one measuring electrode in a one-to-one correspondence. When the number of the at least one measuring electrode 1 is greater than or equal to two, each pair of measuring electrodes 1 forms a measuring electrode group. The current generated by the two AC excitation sources connected to the two measuring electrodes 1 in the measuring electrode group has the same magnitude and frequency, but opposite phase. Thus, when the at least one AC excitation source provides current to the at least one measuring electrode, for the same measuring electrode group, the current flows in from one measuring electrode in the measuring electrode group, passes through the skin of the subject, and flows out from the other measuring electrode in the measuring electrode group.

[0171] When the number of at least one measuring electrode is odd, in addition to each pair of measuring electrodes 1 forming a measuring electrode group, the remaining independent measuring electrode forms a separate measuring electrode group and forms a circuit with the driving electrode. For the same measuring electrode group, the current flows in from one measuring electrode in the measuring electrode group, passes through the skin of the subject, and flows out from the other measuring electrode in the measuring electrode group. For the remaining independent measuring electrode, the current flows in from the independent measuring electrode, passes through the skin of the subject, and flows out from the driving electrode 3.

[0172] The voltage and current at each measuring electrode are obtained, and the contact impedance between each measuring electrode and the subject's skin is calculated based on the voltage and current at each measuring electrode (S805).

[0173] Therefore, in other embodiments, the number of the measuring electrode group can be as little as one, and the driving electrode can also be used as an auxiliary electrode to measure the contact impedance between each measuring electrode and the skin of the subject, thereby realizing the measurement of the contact impedance between each measuring electrode and the skin of the subject. Thus, the contact impedance measurement can still be realized even when there is only one measuring electrode group or when a measuring electrode in a certain measuring electrode group has poor contact or falls off.

[0174] Among them, steps S801-S805 and Figure 7 Steps S601-605 in the document correspond to specific points; for more detailed descriptions, please refer to [link / reference]. Figure 7 A more detailed description of steps S601-605 in the process.

[0175] Among them, the present application Figure 7 , Figure 8 as well as Figure 9 The impedance measurement method shown corresponds to the function of the aforementioned system 100, and the relevant descriptions can be referred to each other.

[0176] In some embodiments, this application also provides a computer-readable storage medium. The computer-readable storage medium may be the aforementioned memory 4, and the computer-readable storage medium stores a plurality of program instructions for execution by the controller 4.

[0177] Among them, multiple program instructions stored in the computer-readable storage medium are executed by the controller 4. Figures 7-9 Some or all of the steps in the method shown in any of the accompanying drawings, or any combination thereof.

[0178] Therefore, this application provides alternating current to the measuring electrode 1 via the AC excitation source 2, which does not interfere with the physiological signal. It enables the simultaneous measurement of physiological parameters by the measuring electrode 1 and the contact impedance between each measuring electrode 1 and the subject's skin, thus providing an indication of the quality of the physiological signal measured by the measuring electrode 1. Furthermore, the operating frequencies of the AC excitation sources 2 connected to the measuring electrodes 1 of different measuring electrode groups 10 are different. Therefore, each measuring electrode group does not affect the measurement of the contact impedance of the measuring electrodes 1 of other measuring electrode groups 10, improving accuracy and achieving synchronization.

[0179] This document describes various exemplary embodiments with reference to them. However, those skilled in the art will recognize that changes and modifications can be made to the exemplary embodiments without departing from the scope of this document. For example, various operational steps and components for performing operational steps can be implemented in different ways depending on the specific application or considering any number of cost functions associated with the operation of the system (e.g., one or more steps can be deleted, modified, or combined with other steps).

[0180] Furthermore, as those skilled in the art will understand, the principles herein can be reflected in a computer program product on a computer-readable storage medium pre-loaded with computer-readable program code. Any tangible, non-transitory computer-readable storage medium may be used, including magnetic storage devices (hard disks, floppy disks, etc.), optical storage devices (CD-ROMs, DVDs, Blu-ray discs, etc.), flash memory, and / or the like. These computer program instructions may be loaded onto a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to form a machine, such that instructions, which execute on the computer or other programmable data processing apparatus, can generate means for performing a specified function. These computer program instructions may also be stored in a computer-readable storage medium that can instruct the computer or other programmable data processing apparatus to operate in a particular manner, such that instructions stored in the computer-readable storage medium can form an article of manufacture, including means for implementing the specified function. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to perform a series of operational steps on the computer or other programmable apparatus to produce a computer-implemented process, such that instructions, which execute on the computer or other programmable apparatus, can provide steps for implementing the specified function.

[0181] While the principles herein have been illustrated in various embodiments, numerous modifications to the structure, arrangement, proportions, elements, materials, and components, particularly suited to specific environmental and operational requirements, may be used without departing from the principles and scope of this disclosure. These modifications and other alterations or alterations will be included within the scope of this document.

[0182] The foregoing specific descriptions have been described with reference to various embodiments. However, those skilled in the art will recognize that various modifications and changes can be made without departing from the scope of this disclosure. Therefore, considerations for this disclosure are to be illustrative rather than restrictive, and all such modifications are to be included within its scope. Similarly, advantages, other advantages, and solutions to problems with respect to various embodiments have been described above. However, benefits, advantages, solutions to problems, and any elements that produce these, or make them more explicit, should not be construed as critical, essential, or necessary. The term “comprising” and any other variations thereof as used herein are non-exclusive inclusion, meaning that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed or not part of the process, method, system, article, or apparatus. Furthermore, the term “coupled” and any other variations thereof as used herein refer to physical connections, electrical connections, magnetic connections, optical connections, communication connections, functional connections, and / or any other connections.

[0183] Those skilled in the art will recognize that many changes can be made to the details of the above embodiments without departing from the basic principles of this application. Therefore, the scope of this application should be determined only by the following claims.

Claims

1. A system for measuring electrode contact resistance, characterized in that, include: At least two measuring electrodes are used to connect to the skin of the subject for measuring physiological parameters, wherein the at least two measuring electrodes form at least two measuring electrode groups; At least two AC excitation sources are provided, and the current output terminals of the at least two AC excitation sources are respectively connected to the at least two measuring electrodes. The operating frequencies of the AC excitation sources connected to the measuring electrodes of different measuring electrode groups are different. A driving electrode is used to connect to the skin of the subject and provide a common-mode potential for the at least two measuring electrodes; The controller, coupled to each measuring electrode, is used to acquire the voltage and current at each measuring electrode and calculate the contact impedance between each measuring electrode and the subject's skin based on the voltage and current at each measuring electrode.

2. The system as described in claim 1, characterized in that, After the measuring electrode in each measuring electrode group receives a current of the corresponding frequency from the current output terminal of the corresponding connected AC excitation source, a small portion of the current of the corresponding frequency will be diverted to other measuring electrode groups. During the measurement of the contact impedance of a certain measuring electrode, the controller acquires a first target voltage of the corresponding frequency in the certain measuring electrode group and acquires a second target voltage of the same frequency from other measuring electrodes that are not in the same measuring electrode group as the certain measuring electrode. Then, the contact impedance of the corresponding measuring electrode is obtained based on the first target voltage, the second target voltage and the current of the corresponding frequency.

3. The system as described in claim 2, characterized in that, The system further includes an inverting amplifier, the input of which is coupled to the at least two measuring electrodes, and the output of which is connected to the driving electrode. The inverting amplifier is used to invert the voltages of the at least two measuring electrodes and apply them to the skin of the subject through the driving electrode, thereby providing a common-mode potential for the at least two measuring electrodes.

4. The system as described in claim 3, characterized in that, The system further includes a computational circuit connected between the at least two measuring electrodes and the input terminal of the inverting amplifier. The computational circuit is used to calculate the voltage of all measuring electrodes to obtain a computational voltage and output it to the input terminal of the inverting amplifier. The inverting amplifier is used to invert the computational voltage and apply it to the skin of the subject through the driving electrodes, thereby providing a common-mode potential for the multiple measuring electrodes.

5. The system as described in claim 1, characterized in that, The number of the at least two AC excitation sources is equal to the number of the at least two measuring electrodes, and the current output terminals of the at least two AC excitation sources are connected to the at least two measuring electrodes in a one-to-one correspondence.

6. The system according to any one of claims 2-5, characterized in that, The controller includes at least one signal input terminal. Each signal input terminal is coupled to the current output terminal of a corresponding AC excitation source and connected to a corresponding measuring electrode. The signal input terminal of the controller is electrically coupled to the measuring electrode. The voltage received by the signal input terminal is equal to the voltage of the measuring electrode. The current of the measuring electrode is the current provided by the AC excitation source connected to the measuring electrode. The controller acquires the current provided by the AC excitation source connected to the measuring electrode and calculates the contact impedance between the measuring electrode and the subject's skin based on the acquired current provided by the AC excitation source connected to the measuring electrode and the voltage of the measuring electrode.

7. The system as described in claim 6, characterized in that, The current provided by each AC excitation source has a corresponding relationship with the signal input terminal of the controller, and the controller determines the current provided by the AC excitation source connected to each signal input terminal based on the corresponding relationship.

8. The system as described in claim 6, characterized in that, The system also includes a current detection circuit, through which the controller detects and acquires the current of each measuring electrode.

9. The system as described in claim 6, characterized in that, During the measurement of the contact impedance of a measuring electrode connected to a certain signal input terminal, the controller filters the voltage collected by the signal input terminal according to the operating frequency of the AC excitation source connected to the signal input terminal, and extracts a first target voltage with the operating frequency of the AC excitation source connected to the signal input terminal. The controller also obtains a second target voltage obtained by filtering the voltage of the signal input terminals of other measuring electrodes not in the same measuring electrode group as the measured electrode, which has the same frequency as the current provided by the AC excitation source connected to the measured electrode. Specifically, the controller calculates the contact impedance between the corresponding measuring electrode and the skin of the subject based on the extracted first target voltage, second target voltage and the current flowing through the corresponding measuring electrode.

10. The system as described in claim 9, characterized in that, The controller first calculates the voltage difference between the first target voltage and the second target voltage, and then calculates the ratio of the voltage difference to the current flowing through the corresponding measuring electrode to obtain the contact impedance between the corresponding measuring electrode and the skin of the subject.

11. The system as described in claim 6, characterized in that, The system also includes at least one signal buffer, each signal buffer being connected between a signal input terminal of the controller and a corresponding AC excitation source.

12. The system according to any one of claims 1-5 and 7-11, characterized in that, The controller is also used to generate an alarm signal when the calculated contact impedance between any measuring electrode and the skin of the subject exceeds a preset threshold.

13. The system as described in claim 12, characterized in that, The alarm signal includes at least one of text, pattern, and video. The controller is also connected to a display. When the calculated contact impedance between any measuring electrode and the skin of the subject exceeds a preset threshold, the controller controls the display to show the alarm signal.

14. The system as described in claim 12, characterized in that, The system also includes an alarm circuit, which is used to output an audible and visual alarm signal. When the calculated contact impedance between any measuring electrode and the skin of the subject exceeds a preset threshold, the controller controls the alarm circuit to output an audible and visual alarm signal.

15. The system as claimed in claim 1, characterized in that, The controller is also connected to a display, which is further configured to control the display to show the physiological signal waveforms obtained by measuring the electrodes and the contact impedance indication of the measuring electrodes, the contact impedance indication being used to indicate the magnitude of the contact impedance of the corresponding measuring electrodes.

16. The system as described in claim 15, characterized in that, The contact impedance indicator includes at least one of color and pattern, and the contact impedance indicator varies depending on the impedance range in which the magnitude of the contact impedance falls.

17. An impedance measurement method, applied in a system for measuring electrode contact impedance, characterized in that, The method includes: At least two measuring electrodes are respectively connected to the skin of the subject, wherein the at least two measuring electrodes form at least two measuring electrode groups; At least two AC excitation sources provide current to the at least two measuring electrodes respectively, wherein the current output terminals of the at least two AC excitation sources are respectively connected to the at least two measuring electrodes, and the operating frequencies of the AC excitation sources connected to the measuring electrodes of different measuring electrode groups are different. The voltage and current at each measuring electrode are obtained, and the contact impedance between each measuring electrode and the subject's skin is calculated based on the voltage and current at each measuring electrode.

18. The method as described in claim 17, characterized in that, After the measuring electrode in each measuring electrode group receives a current of the corresponding frequency from the current output terminal of the corresponding connected AC excitation source, a small portion of the current of the corresponding frequency will be diverted to other measuring electrode groups. The calculation of the contact impedance between each measuring electrode and the subject's skin based on the voltage and current at each measuring electrode includes: During the measurement of the contact impedance of a certain measuring electrode, a first target voltage with a corresponding frequency in the certain measuring electrode group is obtained, and a second target voltage with the same frequency in other measuring electrodes that are not in the same measuring electrode group as the certain measuring electrode is obtained. Then, the contact impedance of the corresponding measuring electrode is obtained based on the first target voltage, the second target voltage and the current with the corresponding frequency.

19. The method as described in claim 18, characterized in that, Each measuring electrode is connected to a corresponding signal input terminal of a controller and coupled to the current output terminal of a corresponding AC excitation source. The signal input terminal of the controller is electrically coupled to the measuring electrode. The voltage collected by the signal input terminal is equal to the voltage of the measuring electrode, and the current provided by the AC excitation source to the corresponding measuring electrode is the current flowing through the corresponding measuring electrode, that is, the current at the measuring electrode. The acquisition of voltage and current at each measuring electrode may include: The voltage at the corresponding measuring electrode is obtained by acquiring the voltage from the signal input terminal of the controller, and the current at the measuring electrode is obtained by acquiring the current provided by the AC excitation source connected to the corresponding measuring electrode.

20. The method as described in claim 19, characterized in that, The method further includes: During the measurement of the contact impedance of a measuring electrode connected to a signal input terminal, the controller filters the voltage collected by the signal input terminal according to the operating frequency of the AC excitation source connected to the signal input terminal, and extracts a first target voltage with the operating frequency of the AC excitation source connected to the signal input terminal. A second target voltage with the same frequency as the current supplied by the AC excitation source connected to the measured electrode is obtained by filtering the voltage of the signal input terminal connected to other measured electrodes or drive electrodes that are not in the same measured electrode group as the measured electrode. The step of determining the contact impedance of the corresponding measuring electrode based on the first target voltage, the second target voltage, and the current at the corresponding frequency includes: The contact impedance between the corresponding measuring electrode and the subject's skin is calculated based on the extracted first target voltage, second target voltage, and current flowing through the corresponding measuring electrode.

21. The method as described in claim 20, characterized in that, The step of calculating the contact impedance between the corresponding measuring electrode and the subject's skin based on the extracted first target voltage, second target voltage, and current flowing through the corresponding measuring electrode includes: First, the voltage difference between the first target voltage and the second target voltage is calculated. Then, the ratio of the voltage difference to the current flowing through the corresponding measuring electrode is calculated to obtain the contact impedance between the corresponding measuring electrode and the skin of the subject.

22. The method according to any one of claims 17-21, characterized in that, The method further includes: When the calculated contact impedance between any measuring electrode and the subject's skin exceeds a preset threshold, an alarm signal is output to trigger an alarm.

23. The method as described in claim 17, characterized in that, The method further includes: The control display shows the physiological signal waveforms obtained by measuring the electrodes and the contact impedance indication of the measuring electrodes, which is used to indicate the magnitude of the contact impedance of the corresponding measuring electrodes in real time.

24. The method as described in claim 23, characterized in that, The contact impedance indicator includes at least one of color and pattern, and the contact impedance indicator varies depending on the impedance range in which the magnitude of the contact impedance falls.

Images