Esophageal impedance detection circuit, device and method

Abstract

The present invention discloses an esophageal impedance detection circuit, comprising: a channel switching control unit, a channel switching unit, an excitation signal source unit, a negative feedback unit, a detection unit, and a signal processing unit; the channel switching control unit is electrically connected to the channel switching unit and is used to control the channel switching unit to switch to a target channel; the excitation signal source unit is connected to the detection unit and the channel switching unit to form a detection loop, and a target parameter of the target channel is obtained through an input signal processing unit; the negative feedback unit is connected in parallel with the detection unit to form a negative feedback loop to maintain the working performance of the detection loop when the channel switching unit switches to any channel. The present invention solves the problems of complex circuit structure, high power consumption and cost, and slow response speed of existing circuits, resulting in a simpler structure, faster response speed, and the ability to complete more measurement tasks.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical impedance measurement and analysis, and in particular to an esophageal impedance detection circuit, device and method. Background Art

[0002] Gastroesophageal reflux disease (GERD) is a common digestive motility disorder. It typically refers to the reflux of gastric or duodenal contents into the esophagus, causing a variety of discomfort or symptoms that seriously impact patients' quality of life. The most common clinical symptoms are heartburn, chest pain, and acid reflux. Currently, the most common and effective method for GERD diagnosis is to monitor physiological parameters such as esophageal impedance and pH for 24 hours or more.

[0003] The demand for more detailed diagnostic data is driving the need for more channels and faster esophageal impedance measurement. Common impedance detection circuits currently offer complex circuit structures, high power consumption and cost, and limited response speed. Therefore, those skilled in the art are striving to develop circuits with a simpler structure, faster response speed, and the ability to perform a wider range of measurement tasks. Summary of the Invention

[0004] In view of the above-mentioned defects of the prior art, the present invention discloses an esophageal impedance detection circuit, device and method to solve the technical problems of the existing impedance detection circuit, such as complex circuit structure, high power consumption and high cost, and slow response speed.

[0005] To achieve the above-mentioned purpose, according to an embodiment of the present invention, the present invention provides an esophageal impedance detection circuit, comprising: a channel switching control unit, a channel switching unit, an excitation signal source unit, a negative feedback unit, a detection unit, and a signal processing unit; the channel switching control unit is electrically connected to the channel switching unit, and is used to control the channel switching unit to switch to a target channel; the first end of the channel switching unit and the third end of the negative feedback unit are respectively connected to an external reference voltage; the first input end of the detection unit is electrically connected to the output end of the excitation signal source unit, and the output end of the detection unit is respectively electrically connected to the output end of the excitation signal source unit, the second end of the channel switching unit and the input end of the signal processing unit to form a detection loop, and the target parameter of the target channel is obtained through the input signal processing unit; the first end of the negative feedback unit is electrically connected to the second input end of the detection unit, and the second end of the negative feedback unit is electrically connected to the output end of the detection unit to form a negative feedback loop, so as to maintain the working performance of the detection loop when the channel switching unit switches to any channel.

[0006] Optionally, the detection unit includes: a high-speed amplifier, a first resistor, a second resistor, and a third resistor; the output end of the excitation signal source unit is connected to the first end of the first resistor, and the second end of the first resistor is respectively connected to the in-phase input end of the high-speed amplifier, the second end of the second resistor, the first end of the third resistor, the second end of the channel switching unit, and the input end of the signal processing unit; the first end of the second resistor and the first end of the channel switching unit are connected to an external reference voltage; the inverting input end of the high-speed amplifier is connected to the first end of the negative feedback unit; and the output end of the high-speed amplifier is respectively connected to the second end of the third resistor and the second end of the negative feedback unit.

[0007] Optionally, the negative feedback unit includes: a fourth resistor and a fifth resistor; the first end of the fifth resistor is connected to an external reference voltage, and the second end of the fifth resistor is respectively connected to the first end of the fourth resistor and the reverse input end of the high-speed amplifier; the second end of the fourth resistor is respectively connected to the output end of the high-speed amplifier and the second end of the third resistor.

[0008] Optionally, the channel switching unit includes: a switch unit array, wherein the switch unit includes a switch unit resistor, a first switch and a second switch; the first end of the first switch is connected to the first end of the channel switching unit, the second end of the first switch is connected to the first end of the switch unit resistor, the second end of the switch unit resistor is connected to the first end of the second switch, and the second end of the second switch is connected to the second end of the channel switching unit.

[0009] Optionally, the esophageal impedance detection circuit further includes a filter enhancement unit, the first end of the filter enhancement unit is respectively connected to the output end of the detection loop and the second end of the channel switching unit; the second end of the filter enhancement unit is connected to the input end of the signal processing unit.

[0010] Optionally, the filtering enhancement unit includes: a sixth resistor, a seventh resistor, an amplifier and a capacitor; the first end of the sixth resistor is connected to the first end of the filtering enhancement unit, and the second end of the sixth resistor is connected to the non-inverting input end of the amplifier; the reverse input end of the amplifier is connected to an external reference voltage, and the output end of the amplifier is connected to the first end of the seventh resistor; the second end of the seventh resistor is respectively connected to the first end of the capacitor and the input end of the signal processing unit; and the second end of the capacitor is grounded.

[0011] Optionally, the excitation signal source unit and the signal processing unit are integrated into a micro control unit.

[0012] To achieve the above object, according to an embodiment of the present invention, the present invention further provides an esophageal impedance detection method, which uses the esophageal impedance detection circuit as described above, and includes the following steps:

[0013] According to a preset program or manual selection, the channel switching control unit sends a signal to control the channel switching unit to switch to the target channel;

[0014] According to the acquisition mode, the excitation signal source unit sends a single or a preset number of excitation waveforms;

[0015] The excitation waveform is passed through the detection unit to obtain an impedance measurement signal, which is then received by the signal processing unit;

[0016] According to the acquisition mode, the signal processing unit analyzes and processes the impedance measurement signal to obtain the impedance detection value of the target channel.

[0017] Optionally, according to the acquisition mode, after the signal processing unit analyzes and processes the impedance measurement signal to obtain the impedance detection value of the target channel, the method further includes:

[0018] According to the preset program or manual selection, multiple target channels are switched and the detection is repeated to obtain the impedance detection value of each target channel;

[0019] The target esophageal impedance detection result is obtained according to the impedance detection value of each target channel.

[0020] An esophageal impedance detection device is characterized by comprising the esophageal impedance detection circuit as described above.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The channel switching control unit sends a signal to control the channel switching unit to switch to the target channel; the excitation signal source unit then sends a single or a preset number of excitation waveforms; the negative feedback unit provides negative feedback for the detection circuit including the detection unit, so that the detection circuit can adapt to various channel switching modes of the channel switching unit and can operate stably and normally at high speed; the impedance measurement signal obtained by the detection unit is then analyzed and processed by the signal processing unit to obtain the impedance detection value of the target channel, and then the detection result of the esophageal impedance detection is obtained through this measurement or multiple measurements by switching the channel. By switching the channel by the channel switching unit, the circuit of the present invention can complete more types of measurement tasks, and by the mutual cooperation between the negative feedback unit and the detection unit, and between the detection unit and the channel switching unit, the circuit structure is simplified under the premise of stability and the response speed is faster. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural diagram of a specific embodiment of the esophageal impedance detection circuit of the present invention;

[0024] Figure 2 is a circuit diagram of an impedance measurement unit of a specific embodiment of an esophageal impedance detection circuit of the present invention;

[0025] Figure 3 It is a structural diagram of a specific embodiment of the esophageal impedance detection circuit of the present invention;

[0026] Figure 4 is a circuit diagram of a switch unit array of a specific embodiment of an esophageal impedance detection circuit of the present invention;

[0027] Figure 5 This is a flow chart of a specific embodiment of the esophageal impedance detection method of the present invention;

[0028] Figure 6 It is a flow chart of a specific implementation method of the esophageal impedance detection method of the present invention.

[0029] In the above figures: U1 is a high-speed amplifier; U2 is an amplifier. DETAILED DESCRIPTION

[0030] The terms "first," "second," and the like in the specification and claims of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that such terms are interchangeable where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. The division of units or modules presented herein is merely a logical division; alternative divisions may be employed in actual implementation. Furthermore, modules or submodules described as separate components may or may not be physically separate, may or may not be physical modules, or may be distributed across multiple circuit modules, with some or all of these modules being selected to achieve the objectives of the embodiments of the present invention as needed. It should be understood that when a component / module is referred to as being "connected" or "coupled" to another component / module, it may be directly connected or directly coupled to the other component / module, or the component / module may also exist. Conversely, when a component / module is referred to as being "directly connected" or "directly coupled" to another component / module, there are no intervening components / modules.

[0031] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The embodiments described with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be understood as limiting the present invention.

[0032] like Figures 1 to 3As shown, the present invention provides an esophageal impedance detection circuit, comprising: a channel switching control unit, a channel switching unit, an excitation signal source unit, a negative feedback unit, a detection unit, and a signal processing unit; the channel switching control unit is electrically connected to the channel switching unit, and is used to control the channel switching unit to switch to a target channel; the first end of the channel switching unit and the third end of the negative feedback unit are respectively connected to an external reference voltage; the first input end of the detection unit is electrically connected to the output end of the excitation signal source unit, and the output end of the detection unit is respectively electrically connected to the output end of the excitation signal source unit, the second end of the channel switching unit and the input end of the signal processing unit to form a detection loop, and the target parameter of the target channel is obtained by inputting the signal processing unit; the first end of the negative feedback unit is electrically connected to the second input end of the detection unit, and the second end of the negative feedback unit is electrically connected to the output end of the detection unit to form a negative feedback loop, so as to maintain the working performance of the detection loop when the channel switching unit switches to any channel.

[0033] In this example, the working principle of the esophageal impedance detection circuit measurement is:

[0034] A signal is sent through the channel switching control unit to control the channel switching unit to switch to the target channel; then a single or a preset number of excitation waveforms are sent by the excitation signal source unit; a negative feedback unit provides negative feedback for the detection circuit including the detection unit, so that the detection circuit can adapt to various channel switching modes of the channel switching unit and can operate stably and normally at high speed; then the impedance measurement signal obtained by the detection unit is analyzed and processed by the signal processing unit to obtain the impedance detection value of the target channel, and then after this measurement or multiple measurements by switching channels, the detection result of the esophageal impedance detection is obtained.

[0035] The channel switching unit can be used to switch the channel to the target channel to measure the impedance under the corresponding target channel. However, because switching between different channels may be necessary during detection, higher requirements are placed on the stability of the circuit. The inventors couple the second end of the negative feedback unit to the output end of the detection unit, so that the potential value of the coupled end is equal to the potential of the corresponding end in the detection circuit, thereby stabilizing the circuit potential, maintaining the working performance of the detection circuit, maintaining high sensitivity, and adapting to higher frequency excitation signal waves, thereby improving efficiency.

[0036] Optionally, the detection unit includes: a high-speed amplifier, a first resistor, a second resistor, and a third resistor; the output end of the excitation signal source unit is connected to the first end of the first resistor, and the second end of the first resistor is respectively connected to the in-phase input end of the high-speed amplifier, the second end of the second resistor, the first end of the third resistor, the second end of the channel switching unit, and the input end of the signal processing unit; the first end of the second resistor and the first end of the channel switching unit are connected to an external reference voltage; the inverting input end of the high-speed amplifier is connected to the first end of the negative feedback unit; and the output end of the high-speed amplifier is respectively connected to the second end of the third resistor and the second end of the negative feedback unit.

[0037] In this example, if Figure 2 As shown, the first resistor R1 is connected in series with the high-speed amplifier, the second resistor R2 is connected in parallel with the resistor to be measured Rx of the target channel switched to, and the third resistor R3 is connected in parallel with the high-speed amplifier. R1, R2, and R3 can select a suitable resistance range or optimal resistance value according to the performance requirements of the selected high-speed amplifier, thereby ensuring that the entire circuit works normally, avoiding exceeding the performance index requirements of the high-speed amplifier U1, avoiding the loss of impedance measurement function, or waveform distortion causing inaccurate measurement, and further enhancing the adaptability of detection switching for different target channels.

[0038] Optionally, the negative feedback unit includes: a fourth resistor and a fifth resistor; the first end of the fifth resistor is connected to an external reference voltage, and the second end of the fifth resistor is respectively connected to the first end of the fourth resistor and the reverse input end of the high-speed amplifier; the second end of the fourth resistor is respectively connected to the output end of the high-speed amplifier and the second end of the third resistor.

[0039] In this example, if Figure 2 As shown, the negative feedback unit can be composed of a fifth resistor R5 connected in series with the high-speed amplifier and a fourth resistor R4 connected in parallel with the high-speed amplifier. As shown in the figure, the fourth resistor R4 and the fifth resistor can form negative feedback on the parallel circuit from the third resistor R3 to the second resistor R2 and the resistor to be measured Rx, ensuring that the detection circuit does not saturate, thereby maintaining the working performance of the detection circuit and maintaining high sensitivity, thereby adapting to higher frequency excitation signal waves and improving efficiency.

[0040] Optionally, the channel switching unit includes: a switch unit array, wherein the switch unit includes a switch unit resistor, a first switch and a second switch; the first end of the first switch is connected to the first end of the channel switching unit, the second end of the first switch is connected to the first end of the switch unit resistor, the second end of the switch unit resistor is connected to the first end of the second switch, and the second end of the second switch is connected to the second end of the channel switching unit.

[0041] In this example, if Figure 4As shown, a configuration of a switch array is shown, wherein the switch array is composed of a plurality of switch units, and a circuit of a switch unit includes one or more switch unit resistors (R X1 ~R XN ), and two switches, by selecting Figure 4 The conduction of two or more switches in the circuit can make the circuit conductive, that is, the resistance of the switch unit (R X1 ~R XN ) Any combination of switch unit resistance. High-speed switches can be used to complete the switching of impedance channels, making it have good impedance channel expansion.

[0042] Optionally, the esophageal impedance detection circuit further includes a filter enhancement unit, the first end of the filter enhancement unit is respectively connected to the output end of the detection loop and the second end of the channel switching unit; the second end of the filter enhancement unit is connected to the input end of the signal processing unit.

[0043] Optionally, the filtering enhancement unit includes: a sixth resistor, a seventh resistor, an amplifier and a capacitor; the first end of the sixth resistor is connected to the first end of the filtering enhancement unit, and the second end of the sixth resistor is connected to the non-inverting input end of the amplifier; the reverse input end of the amplifier is connected to an external reference voltage, and the output end of the amplifier is connected to the first end of the seventh resistor; the second end of the seventh resistor is respectively connected to the first end of the capacitor and the input end of the signal processing unit; and the second end of the capacitor is grounded.

[0044] In this example, if Figure 2 As shown, U2 is an amplifier, which can be a high-speed amplifier, an instrumentation amplifier, etc. U2 amplifies the impedance detection signal Vout, and after passing through a low-pass filter network composed of a seventh resistor R7 and a capacitor C1 to filter out high-frequency interference, the signal processing unit performs full-wave acquisition and completes the impedance calculation through an algorithm.

[0045] As mentioned above, the fourth and fifth resistors R4 and R5 provide negative feedback for the circuit, ensuring that the detection circuit does not saturate. R1 is located between the excitation signal and the positive input of U1. The second resistor R2 is connected in parallel with the resistor to be measured and is located between the reference voltage VREF and the positive input of U1. The third resistor R3 is located between the positive input of U1 and the output of U1.

[0046] Assuming R = Rx / / R2, the maximum and minimum output values ​​of the op amp are Vomax and Vomin, respectively. From the characteristics of the op amp, we can know that:

[0047]

[0048]

[0049] Vn=Vp=Vout

[0050] Vo max≤Vout≤Vo min

[0051] Assuming R1=R3, R4=R5, we can know from the above that:

[0052]

[0053] At the same time, Vout should also meet the U2 input voltage requirements. Assuming that the minimum and maximum input voltages of U2 are Uimin and Uimax respectively, then:

[0054] at the same time,

[0055] Therefore, R1, R2, and R3 should be selected with appropriate values ​​based on requirements to ensure proper operation of the entire circuit and avoid exceeding the performance requirements of U1 and U2, which could lead to loss of impedance measurement functionality or inaccurate measurements due to waveform distortion. When these requirements are met, the formula shows that R and Vout have a linear relationship. Given the peak value of the excitation signal Vin and measuring the peak value of the signal to be measured, the resistance value of R can be derived, and the impedance of the resistor to be measured, Rx, can be further calculated. Therefore, the circuit in this example implements impedance acquisition in a simple manner, with a high response rate and the ability to quickly identify impedance changes.

[0056] To verify that the Figure 2 To demonstrate the effectiveness of the esophageal impedance detection circuit, the inventors used this circuit to conduct five-channel impedance acquisition tests using precision resistors (1kΩ, 5kΩ, and 10kΩ) at different impedance acquisition frequencies. The maximum and minimum impedance measurements were recorded for one minute to verify the accuracy of the impedance measurements.

[0057]

[0058]

[0059] From the above data, we can see that when the single-channel acquisition frequency is 1kHz, 2kHz and 4kHz, Figure 6 In the single excitation waveform detection mode (non-high-precision mode) shown, the acquisition accuracy for impedances of 1kΩ, 5kΩ, and 10kΩ all meets the ±5% error range (the test value of a 1kΩ standard resistor is within the error range of 1kΩ*(1-0.05) to 1kΩ(1+0.05)). This accuracy is sufficient for most impedance acquisition environments, even when detecting only a single high-frequency excitation waveform. Of course, in theory, this circuit can be configured with a higher acquisition frequency based on actual needs.

[0060] Optionally, the excitation signal source unit and the signal processing unit are integrated into a micro control unit.

[0061] In this example, if Figure 3 As shown, the excitation signal source unit and the signal processing unit are integrated into the micro control unit. Similarly, the detection unit, the negative feedback unit and the filter enhancement unit are composed as shown in FIG. Figure 3 The impedance measurement unit shown, as a complete structural whole that interacts with each other, achieves a high-speed response and can quickly identify the function of impedance changes.

[0062] To achieve the above object, according to an embodiment of the present invention, the present invention further provides an esophageal impedance detection method, which uses the esophageal impedance detection circuit as described above, and includes the following steps:

[0063] According to a preset program or manual selection, the channel switching control unit sends a signal to control the channel switching unit to switch to the target channel;

[0064] According to the acquisition mode, the excitation signal source unit sends a single or a preset number of excitation waveforms;

[0065] The excitation waveform is passed through the detection unit to obtain an impedance measurement signal, which is then received by the signal processing unit;

[0066] According to the acquisition mode, the signal processing unit analyzes and processes the impedance measurement signal to obtain the impedance detection value of the target channel.

[0067] Optionally, according to the acquisition mode, after the signal processing unit analyzes and processes the impedance measurement signal to obtain the impedance detection value of the target channel, the method further includes:

[0068] According to the preset program or manual selection, multiple target channels are switched and the detection is repeated to obtain the impedance detection value of each target channel;

[0069] The target esophageal impedance detection result is obtained according to the impedance detection value of each target channel.

[0070] In this example, if Figure 5 、 Figure 6 As shown, the following steps are included:

[0071] S1 According to a preset program or manual selection, the channel switching control unit sends a signal to control the channel switching unit to switch to the target channel;

[0072] In this step, a complete set of tests can be completed by manually selecting channels or converting each channel in sequence according to a pre-set program.

[0073] S2: The excitation signal source unit sends a single or a preset number of excitation waveforms according to the acquisition mode;

[0074] In this step, impedance measurement can be performed on a single excitation waveform, and the full-wave output waveform Vad of that unit can be immediately acquired. The peak value of this waveform can be determined to calculate the impedance of the resistor under test. Alternatively, in high-precision acquisition mode, the number of excitation waveforms should be set first, and the impedance calculation results within the set number of waveforms should be averaged to obtain the impedance measurement result, thus completing the high-precision impedance measurement result for the channel.

[0075] The S3 excitation waveform passes through the detection unit to obtain an impedance measurement signal, which is then received by the signal processing unit;

[0076] The signal processing unit accepts Figure 2 The Vout signal shown in FIG. 1 may be received and analyzed by the signal processing unit after being filtered out of high-frequency interference by a low-pass filter network composed of a seventh resistor R7 and a capacitor C1 .

[0077] S4: According to the acquisition mode, the signal processing unit analyzes and processes the impedance measurement signal to obtain the impedance detection value of the target channel.

[0078] In this step, if the full-wave unit output waveform Vad is acquired according to S2, the peak value of the waveform is determined to calculate the impedance of the resistor under test. Alternatively, in high-precision acquisition mode, the number of excitation waveforms should be set first, and the impedance calculation results within the set number of waveforms are averaged to obtain the impedance measurement result, thereby completing the high-precision measurement of the channel impedance.

[0079] An esophageal impedance detection device is characterized by comprising the esophageal impedance detection circuit as described above.

[0080] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort, such as various combinations of circuit units that do not affect the underlying invention. Therefore, any technical solution that can be derived by those skilled in the art based on the concepts of the present invention through logical analysis, reasoning, or limited experimentation based on the prior art should be within the scope of protection defined by the claims.

Claims

1. An esophageal impedance detection circuit, characterized in that: include: Channel switching control unit, channel switching unit, excitation signal source unit, negative feedback unit, detection unit, signal processing unit; The channel switching control unit is electrically connected to the channel switching unit, and is used to control the channel switching unit to switch to the target channel; The first terminal of the channel switching unit and the third terminal of the negative feedback unit are respectively connected to an external reference voltage; The first input end of the detection unit is electrically connected to the output end of the excitation signal source unit, and the output end of the detection unit is electrically connected to the output end of the excitation signal source unit, the second end of the channel switching unit, and the input end of the signal processing unit to form a detection loop, and the target parameter of the target channel is obtained through the input signal processing unit; The first end of the negative feedback unit is electrically connected to the second input end of the detection unit, and the second end of the negative feedback unit is electrically connected to the output end of the detection unit to form a negative feedback loop for maintaining the working performance of the detection loop when the channel switching unit switches to any channel; The detection unit includes: a high-speed amplifier, a first resistor, a second resistor, and a third resistor; The output end of the excitation signal source unit is connected to the first end of the first resistor, and the second end of the first resistor is respectively connected to the non-inverting input end of the high-speed amplifier, the second end of the second resistor, the first end of the third resistor, the second end of the channel switching unit, and the input end of the signal processing unit; The first end of the second resistor and the first end of the channel switching unit are connected to an external reference voltage; The inverting input terminal of the high-speed amplifier is connected to the first terminal of the negative feedback unit; the output terminal of the high-speed amplifier is connected to the second terminal of the third resistor and the second terminal of the negative feedback unit respectively; The negative feedback unit includes: a fourth resistor and a fifth resistor; The first end of the fifth resistor is connected to the external reference voltage, and the second end of the fifth resistor is connected to the first end of the fourth resistor and the inverting input end of the high-speed amplifier respectively; The second end of the fourth resistor is connected to the output end of the high-speed amplifier and the second end of the third resistor respectively.

2. The esophageal impedance detection circuit according to claim 1, wherein: The channel switching unit includes: a switch unit array, wherein the switch unit includes a switch unit resistor, a first switch, and a second switch; the first end of the first switch is connected to the first end of the channel switching unit, the second end of the first switch is connected to the first end of the switch unit resistor, the second end of the switch unit resistor is connected to the first end of the second switch, and the second end of the second switch is connected to the second end of the channel switching unit.

3. The esophageal impedance detection circuit according to claim 1, wherein: It also includes a filtering enhancement unit, the first end of which is connected to the output end of the detection circuit and the second end of the channel switching unit respectively; the second end of the filtering enhancement unit is connected to the input end of the signal processing unit.

4. The esophageal impedance detection circuit according to claim 3, wherein: The filtering enhancement unit includes: a sixth resistor, a seventh resistor, an amplifier and a capacitor; The first end of the sixth resistor is connected to the first end of the filtering enhancement unit, and the second end of the sixth resistor is connected to the non-inverting input end of the amplifier; The amplifier inverting input terminal is connected to an external reference voltage, and the amplifier output terminal is connected to the first terminal of the seventh resistor; The second end of the seventh resistor is connected to the first end of the capacitor and the input end of the signal processing unit respectively; The second terminal of the capacitor is grounded.

5. The esophageal impedance detection circuit according to claim 1, characterized in that The excitation signal source unit and the signal processing unit are integrated into a micro control unit.

6. A method for detecting esophageal impedance, characterized in that: Using the esophageal impedance detection circuit according to any one of claims 1 to 5 comprises the following steps: According to a preset program or manual selection, the channel switching control unit sends a signal to control the channel switching unit to switch to the target channel; According to the acquisition mode, the excitation signal source unit sends a preset number of excitation waveforms; The excitation waveform is passed through the detection unit to obtain an impedance measurement signal, which is then received by the signal processing unit; According to the acquisition mode, the signal processing unit analyzes and processes the impedance measurement signal to obtain the impedance detection value of the target channel.

7. The esophageal impedance detection method according to claim 6, characterized in that: According to the acquisition mode, the signal processing unit analyzes and processes the impedance measurement signal to obtain the impedance detection value of the target channel, and further includes: According to the preset program or manual selection, multiple target channels are switched and the detection is repeated to obtain the impedance detection value of each target channel; The target esophageal impedance detection result is obtained according to the impedance detection value of each target channel.

8. An esophageal impedance detection device, characterized in that: The method comprises the esophageal impedance detection circuit according to any one of claims 1 to 5.

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