Electrical impedance imaging signal acquisition circuit and acquisition equipment

Abstract

The utility model relates to the technical field of electrical impedance imaging, in particular to an electrical impedance imaging signal acquisition circuit and an acquisition device, the electrical impedance imaging signal acquisition circuit comprises an excitation signal generation circuit and a measurement signal detection circuit, a first voltage follower circuit is arranged in the measurement signal detection circuit in series, and a second voltage follower circuit is arranged in the measurement signal detection circuit. The first voltage following circuit can increase the input impedance of the measurement signal detection circuit, so that the measurement signal detection circuit is equivalent to an ideal voltmeter, and almost does not draw current from a motor of the excitation signal generation circuit, thereby enabling the voltage of a motor signal not to be remarkably changed, reducing the influence on the motor signal, and improving the reliability of the motor. And the authenticity and integrity of the measurement signal are ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of electrical impedance imaging, in particular to an electrical impedance imaging signal acquisition circuit and acquisition equipment. Background Art

[0002] Electrical Impedance Tomography (EIT) is a medical imaging technique that uses low-intensity current or voltage pulses to pass through a series of electrodes placed on the surface of human tissue. This technology is based on the fact that tissues and organs have different electrical impedance properties (i.e. resistivity and conductivity) under different physiological and pathological conditions. The EIT system applies a current within a safe range to the body surface and detects the resulting voltage changes through the same group of electrodes or another group of electrodes, and then reconstructs a two-dimensional or three-dimensional image of the resistivity distribution in the body through complex mathematical algorithms.

[0003] In the prior art, when acquiring the signal of the sample through the electrode array, since the signal includes some current signals, the voltage of the motor providing the excitation signal changes suddenly, affecting the normal working state and output signal quality of the motor, and further causing the actual measured voltage signal to be inconsistent with the original signal, seriously affecting the accuracy of image reconstruction. Utility Model Content

[0004] The embodiment of the utility model provides an electrical impedance imaging signal acquisition circuit and acquisition equipment to solve the problem in the prior art that the sample signal obtained includes part of the current signal, resulting in the actual measured voltage signal being inconsistent with the original signal, which seriously affects the accuracy of image reconstruction.

[0005] In the first aspect, the utility model provides an electrical impedance imaging signal acquisition circuit, comprising: an excitation signal generating circuit and a measurement signal detection circuit, wherein the input end of the excitation signal generating circuit is electrically connected to a processor, the output end of the excitation signal generating circuit is electrically connected to an electrode array, the input end of the measurement signal detection circuit is electrically connected to the electrode array, the output end of the measurement signal detection circuit is electrically connected to the processor, and a first voltage follower circuit is serially arranged in the measurement signal detection circuit, and the first voltage follower circuit is used to increase the impedance of the measurement signal detection circuit.

[0006] In one embodiment, the measurement signal detection circuit further includes: a first amplitude adjustment circuit, an input end of the first amplitude adjustment circuit is electrically connected to the first voltage follower circuit, and an output end of the first amplitude adjustment circuit is electrically connected to the processor.

[0007] In one embodiment, the measurement signal detection circuit also includes: a differential amplifier circuit, a first filter circuit, a programmable amplifier circuit and a first differential conversion circuit, the input end of the differential amplifier circuit is electrically connected to the electrode array, the output end of the differential amplifier circuit is connected to the input end of the first voltage follower circuit, the output end of the first voltage follower circuit is connected to the input end of the first filter circuit, the output end of the first filter circuit is connected to the input end of the programmable amplifier circuit, the control end of the programmable amplifier circuit is electrically connected to the processor, the output end of the programmable amplifier circuit is connected to the input end of the first amplitude adjustment circuit, the control end of the first amplitude adjustment circuit is electrically connected to the processor, the output end of the first amplitude adjustment circuit is connected to the input end of the first differential conversion circuit, and the output end of the first differential conversion circuit is electrically connected to the processor.

[0008] In one embodiment, the first voltage follower circuit includes: a first operational amplifier, a first voltage divider branch, and a second voltage divider branch, one end of the first voltage divider branch is connected to the output end of the differential amplifier circuit, the other end of the first voltage divider branch is connected to the non-inverting input end of the first operational amplifier, one end of the second voltage divider branch is connected to the non-inverting input end of the first operational amplifier, the other end of the second voltage divider branch is grounded, the inverting input end of the first operational amplifier is connected to the output end of the first operational amplifier, and the output end of the first operational amplifier is connected to the input end of the first filter circuit.

[0009] In one embodiment, the first amplitude adjustment circuit includes: a digital potentiometer, a control end of the digital potentiometer is electrically connected to the processor, an input end of the digital potentiometer is connected to an output end of the programmable amplifier circuit, and an output end of the digital potentiometer is connected to an input end of the first differential conversion circuit.

[0010] In one embodiment, the excitation signal generating circuit includes: a second filter circuit and a voltage-controlled constant current source circuit, the input end of the second filter circuit is electrically connected to the processor, the output end of the second filter circuit is connected to the input end of the voltage-controlled constant current source circuit, and the output end of the voltage-controlled constant current source circuit is electrically connected to the electrode array.

[0011] In one embodiment, the electrical impedance imaging signal acquisition circuit also includes: a reference signal detection circuit, wherein the input end of the reference signal detection circuit is electrically connected to the electrode array, the output end of the reference signal detection circuit is electrically connected to the processor, and a second voltage follower circuit is connected in series in the reference signal detection circuit, and the second voltage follower circuit is used to increase the impedance of the reference signal detection circuit.

[0012] In one embodiment, the reference signal detection circuit further includes: a second amplitude adjustment circuit, an input end of the second amplitude adjustment circuit is electrically connected to the second voltage follower circuit, and an output end of the second amplitude adjustment circuit is electrically connected to the processor.

[0013] In one embodiment, the reference signal detection circuit also includes: a third filtering circuit and a second differential conversion circuit, the input end of the second voltage follower circuit is electrically connected to the electrode array, the output end of the second voltage follower circuit is connected to the input end of the third filtering circuit, the output end of the third filtering circuit is connected to the input end of the second differential conversion circuit, and the output end of the second differential conversion circuit is electrically connected to the processor.

[0014] In a second aspect, the present embodiment provides an electrical impedance imaging signal acquisition device, the electrical impedance imaging signal acquisition device comprising: a device housing, wherein the electrical impedance imaging signal acquisition circuit as described in the first aspect and its improvement is arranged in the device housing.

[0015] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0016] The electrical impedance imaging signal acquisition circuit of the utility model comprises: an excitation signal generating circuit and a measurement signal detecting circuit. A first voltage following circuit is serially connected in the measurement signal detecting circuit. The first voltage following circuit can increase the input impedance of the measurement signal detecting circuit, so that the measurement signal detecting circuit is equivalent to an ideal voltmeter and hardly draws current from the motor of the excitation signal generating circuit, so that the voltage of the motor signal does not change significantly, reducing the influence on the motor signal and ensuring the authenticity and integrity of the measurement signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments of the utility model will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 It is a schematic diagram of the module structure of an electrical impedance imaging signal acquisition circuit provided by an embodiment of the utility model;

[0019] Figure 2 It is a schematic diagram of the module structure of an electrical impedance imaging signal acquisition circuit provided by an embodiment of the utility model;

[0020] Figure 3 It is a circuit connection diagram of a differential amplifier circuit provided in one embodiment of the utility model;

[0021] Figure 4 It is a circuit connection diagram of a program-controlled amplifier circuit provided in one embodiment of the utility model;

[0022] Figure 5 This is a circuit connection diagram of a first differential conversion circuit provided in one embodiment of the utility model;

[0023] Figure 6 It is a circuit connection diagram of a first voltage follower circuit provided by an embodiment of the utility model;

[0024] Figure 7 It is a circuit connection diagram of a first amplitude adjustment circuit provided by an embodiment of the utility model;

[0025] Figure 8 It is a schematic diagram of the module structure of an excitation signal generating circuit provided by an embodiment of the utility model;

[0026] Fig. 9 It is a schematic diagram of the module structure of a reference signal detection circuit provided in one embodiment of the utility model;

[0027] Fig.10 It is a circuit connection diagram of a second voltage follower circuit provided by an embodiment of the utility model;

[0028] Among them, 1. excitation signal generating circuit, 2. measurement signal detecting circuit, 3. processor, 4. electrode array, 5. reference absorption detection circuit, 11. second filtering circuit, 12. voltage-controlled constant current source circuit, 21. first voltage following circuit, 22. first amplitude adjusting circuit, 23. differential amplifier circuit, 24. first filtering circuit, 25. program-controlled amplifier circuit, 26. first differential conversion circuit, 51. second voltage following circuit, 52. second amplitude adjusting circuit, 53. third filtering circuit, 54. second differential conversion circuit, 211. first voltage dividing branch, 212. second voltage dividing branch. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects solved by the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0030] In the description of the present invention, it should be understood that the terms "longitudinal", "radial", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0031] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] In order to thoroughly understand the present invention, detailed structures and steps will be presented in the following description to illustrate the technical solution proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0033] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure belongs. It will be further understood that the terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined as such herein.

[0034] In one embodiment, if Figure 1 As shown, a module structure schematic diagram of an electrical impedance imaging signal acquisition circuit is provided, including: an excitation signal generating circuit 1 and a measurement signal detecting circuit 2, wherein the input end of the excitation signal generating circuit 1 is electrically connected to a processor 3, the output end of the excitation signal generating circuit 1 is electrically connected to an electrode array 4, the input end of the measurement signal detecting circuit 2 is electrically connected to the electrode array 4, the output end of the measurement signal detecting circuit 2 is electrically connected to the processor 3, and a first voltage follower circuit 21 is serially connected in the measurement signal detecting circuit 2, and the first voltage follower circuit 21 is used to increase the impedance of the measurement signal detecting circuit 2.

[0035] The size of the input signal of the first voltage follower circuit 21 is the same as the size of the output signal. The first voltage follower circuit 21 only increases the impedance of the circuit. A single operational amplifier can be set in the first voltage follower circuit 21 to increase the impedance of the circuit. A multi-channel operational amplifier can also be set in the first voltage follower circuit 21 to increase the impedance of the circuit through a certain operational amplifier in the multi-channel operational amplifier.

[0036] It is understandable that a digital-to-analog conversion circuit should be provided between the input end of the excitation signal generating circuit 1 and the processor 3, and the signal output by the processor 3 is transmitted to the excitation signal generating circuit 1 through the digital-to-analog conversion circuit. An analog switch should be provided between the output end of the excitation signal generating circuit 1 and the electrode array 4. The excitation signal output by the output end of the excitation signal generating circuit 1 is selected by the analog switch, and the excitation signal is transmitted to the preset electrode in the electrode array 4.

[0037] An analog switch is arranged between the input end of the measurement signal detection circuit 2 and the electrode array 4. The measurement signal detection circuit 2 selects different groups of electrodes through the analog switch for signal processing to obtain a measurement signal. An analog-to-digital converter should be arranged between the output end of the measurement signal detection circuit 2 and the processor 3. The measurement signal at the output end of the measurement signal detection circuit 2 is transmitted to the processor 3 through the analog-to-digital converter.

[0038] A constant current source may be provided in the excitation signal generating circuit 1 to generate an excitation signal, and an amplifier may be provided in the measurement signal detecting circuit 2 to amplify the signal collected from the electrode. Preferably, the amplifier is a programmable amplifier.

[0039] The measurement signal detection circuit 2 may only obtain the amplitude signal, or the measurement signal detection circuit 2 may obtain the amplitude signal and the phase signal. Preferably, the measurement signal detection circuit 2 obtains the amplitude signal and the phase signal so that the reconstructed image contains more information.

[0040] The working process of the above-mentioned electrical impedance imaging signal acquisition circuit is: using the excitation signal generation circuit 1 to convert the signal output by the processor 3 into a current signal, and transmit it to the electrode array 4 for electrode excitation, the measurement signal is collected by the measurement signal detection circuit 2 and transmitted to the processor 3, and the processor 3 processes the signal and reconstructs a two-dimensional or three-dimensional image of the resistivity distribution in the body, wherein the first voltage follower circuit 21 in the measurement signal detection circuit 2 can increase the impedance, so that the measurement circuit is equivalent to an ideal voltmeter.

[0041] The electrical impedance imaging signal acquisition circuit of the present embodiment includes an excitation signal generating circuit 1 and a measurement signal detection circuit 2. A first voltage follower circuit 21 is serially connected in the measurement signal detection circuit 2. The first voltage follower circuit 21 can increase the input impedance of the measurement signal detection circuit 2, so that the measurement signal detection circuit 2 is equivalent to an ideal voltmeter and hardly draws current from the motor of the excitation signal generating circuit 1, so that the voltage of the motor signal does not change significantly, reducing the impact on the motor signal and ensuring the authenticity and integrity of the measurement signal.

[0042] like Figure 2 As shown, a schematic diagram of the module structure of an electrical impedance imaging signal acquisition circuit is provided.

[0043] In one embodiment, if Figure 2 As shown in the above Figure 1 Based on the electrical impedance imaging signal acquisition circuit shown, the measurement signal detection circuit 2 also includes: a first amplitude adjustment circuit 22, the input end of the first amplitude adjustment circuit 22 is electrically connected to the first voltage follower circuit 21, and the output end of the first amplitude adjustment circuit 22 is electrically connected to the processor 3.

[0044] An amplifier circuit should be provided at the front end of the first amplitude adjustment circuit 22, and the first amplitude adjustment circuit 22 adjusts the amplified signal to a preset magnitude.

[0045] Specifically, a digital potentiometer may be provided in the first amplitude adjustment circuit 22 to adjust the amplitude of the measurement signal, an operational amplifier may be provided in the first amplitude adjustment circuit 22 to adjust the amplitude of the measurement signal, an oscillator may be provided in the first amplitude adjustment circuit 22 to adjust the amplitude of the measurement signal, and preferably, a digital potentiometer is provided in the first amplitude adjustment circuit 22 for adjustment.

[0046] The working process of the electrical impedance imaging signal acquisition circuit is as follows: the first amplitude adjustment circuit 22 adjusts the amplified signal to a preset magnitude, and then inputs the signal into the processor 3 .

[0047] The electrical impedance imaging signal acquisition circuit of this embodiment uses the first amplitude adjustment circuit 22 to adjust the amplified signal, which can compensate for the impedance error caused by the uneven length of the electrode lines in the electrode array 4, and further improve the quality of the measurement signal.

[0048] In one embodiment, if Figure 2As shown, on the basis of the above embodiment, the measurement signal detection circuit 2 also includes: a differential amplifier circuit 23, a first filter circuit 24, a programmable amplifier circuit 25 and a first differential conversion circuit 26, the input end of the differential amplifier circuit 23 is electrically connected to the electrode array 4, the output end of the differential amplifier circuit 23 is connected to the input end of the first voltage follower circuit 21, the output end of the first voltage follower circuit 21 is connected to the input end of the first filter circuit 24, the output end of the first filter circuit 24 is connected to the input end of the programmable amplifier circuit 25, the control end of the programmable amplifier circuit 25 is electrically connected to the processor 3, the output end of the programmable amplifier circuit 25 is connected to the input end of the first amplitude adjustment circuit 22, the control end of the first amplitude adjustment circuit 22 is electrically connected to the processor 3, the output end of the first amplitude adjustment circuit 22 is connected to the input end of the first differential conversion circuit 26, and the output end of the first differential conversion circuit 26 is electrically connected to the processor 3.

[0049] It is understandable that the differential amplifier circuit 23 in this embodiment is any differential amplifier circuit. Preferably, the circuit connection diagram of the differential amplifier circuit 23 is as shown in FIG. Figure 3 As shown, a differential amplifier circuit 23 is formed by using a differential amplifier U11, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a resistor R27, a capacitor C72, a capacitor C80 and a capacitor C79. The signal output by the electrode array 4 is transmitted to the capacitor C72 and the capacitor C80 through an analog switch. The capacitor C72, the capacitor C80, the resistor R23, the resistor R24, the resistor R27 protect the differential amplifier. The resistor R26 is a gain resistor for adjusting the amplification factor of the differential amplifier U11. There is a noise signal in the signal output by the electrode array 4, and the differential amplification factor is not easy to be too large. The differential amplifier U11 converts the bipolar signal into a unipolar signal and transmits it to the first filter circuit 24 for filtering.

[0050] The first filter circuit 24 may be any type of filter circuit. The first filter circuit 24 may be an RC filter circuit, the first filter circuit 24 may be an RL filter circuit, or the first filter circuit 24 may be an LC filter circuit. Preferably, the first filter circuit 24 is an LC filter circuit.

[0051] The program-controlled amplifier circuit 25 is provided with a program-controlled gain amplifier. The program-controlled gain amplifier is controlled by the processor 3 according to the actual application situation to amplify the signal filtered by the first filter circuit 24. Preferably, the program-controlled amplifier circuit 25 is as follows: Figure 4 As shown, the power supply terminal of the programmable amplifier U12 is connected to a power supply.

[0052] The first differential conversion circuit 26 is arranged at the output end of the first amplitude adjustment circuit 22. The first differential conversion circuit 26 converts the unipolar signal adjusted by the first amplitude adjustment circuit 22 into a bipolar signal, that is, a differential signal. The differential signal is transmitted to the processor 3 through the analog-to-digital conversion circuit. Preferably, as Figure 5 As shown, a multi-stage differential amplifier U15 is provided in the first differential conversion circuit 26. The model of the multi-stage differential amplifier U15 is LTC6403IUD-1. A plurality of capacitors are also provided at the power supply end of the multi-stage differential amplifier U15 to protect the multi-stage differential amplifier U15.

[0053] The working process of the above-mentioned electrical impedance imaging signal acquisition circuit is as follows: the signal output by the electrode array 4 is input to the differential amplifier circuit 23 through the analog switch, the differential amplifier circuit 23 amplifies the signal and transmits it to the first voltage follower circuit 21, and enters the first filter circuit 24 for filtering after passing through the first voltage follower circuit 21, and the first filter circuit 24 filters the signal and transmits it to the programmable amplifier circuit 25, the processor 3 controls the programmable gain amplifier in the programmable amplifier circuit 25 to amplify, and then controls the first amplitude adjustment circuit 22 to adjust the amplified absorption, and the adjusted signal is transmitted to the first differential conversion circuit 26, the first differential conversion circuit 26 converts the unipolar signal adjusted by the first amplitude adjustment circuit 22 into a bipolar signal and transmits it to the analog-to-digital conversion circuit, and the analog-to-digital conversion circuit performs analog-to-digital conversion and transmits it to the processor 3.

[0054] The electrical impedance imaging signal acquisition circuit of this embodiment uses a programmable amplifier circuit 25 to perform programmable amplification on the signal output by the first filter circuit 24, further compensating for the impedance error caused by the uneven length of the electrode wires in the electrode array 4, greatly improving the quality of the measurement signal, and using the first differential conversion circuit 26 to achieve high-speed acquisition.

[0055] In one embodiment, if Figure 6 As shown, a circuit connection diagram of a first voltage follower circuit 21 is provided. Figure 2 On the basis of the electrical impedance imaging signal acquisition circuit shown, the first voltage follower circuit includes: a first operational amplifier U13A, a first voltage divider branch 211 and a second voltage divider branch 212, one end of the first voltage divider branch 211 is connected to the output end of the differential amplifier circuit 23, the other end of the first voltage divider branch 211 is connected to the in-phase input end of the first operational amplifier U13A, one end of the second voltage divider branch 212 is connected to the in-phase input end of the first operational amplifier U13A, the other end of the second voltage divider branch 212 is grounded, the inverting input end of the first operational amplifier U13A is connected to the output end of the first operational amplifier U13A, and the output end of the first operational amplifier U13A is connected to the input end of the first filter circuit 24.

[0056] The first operational amplifier U13A may be a separate operational amplifier, or may be a certain operational amplifier in a multi-channel operational amplifier. In this embodiment, the first operational amplifier U13A is one of the dual-channel operational amplifiers.

[0057] Specifically, the first voltage follower circuit 21 includes: a dual-channel operational amplifier U13, a first capacitor C81, a second capacitor C82, a third capacitor C87, a fourth capacitor C89, a first resistor R28 and a second resistor R32, one end of the first capacitor C81 is connected to the output end of the differential amplifier circuit 23, the other end of the first capacitor C81 is connected to the in-phase input end of the first channel operational amplifier U13A of the dual-channel operational amplifier U13, the second capacitor C82 is connected in parallel with the first capacitor C81, the first resistor R28 is connected in parallel with the first capacitor C81, one end of the third capacitor C87 is connected to the other end of the first capacitor C81, the other end of the third capacitor C87 is grounded, the second resistor R32 is connected in parallel with the third capacitor C87, and the dual-channel operational amplifier The output end of the first channel operational amplifier U13A of the dual-channel operational amplifier U13 is connected to the input end of the first filtering circuit 24, the output end of the first channel operational amplifier U13A of the dual-channel operational amplifier U13 is connected to the inverting input end of the first channel operational amplifier U13A of the dual-channel operational amplifier U13, the non-inverting input end of the second channel operational amplifier U13B of the dual-channel operational amplifier U13 is grounded, the inverting input end of the second channel operational amplifier U13B of the dual-channel operational amplifier U13 is connected to the output end of the second channel operational amplifier U13B of the dual-channel operational amplifier U13, the output end of the second channel operational amplifier U13B of the dual-channel operational amplifier U13 is connected to one end of the fourth capacitor C89, and the other end of the fourth capacitor C89 is grounded.

[0058] The working process of the above-mentioned impedance imaging signal acquisition circuit is as follows: the signal output from the output end of the differential amplifier circuit 23 flows to the non-inverting input end of the first channel operational amplifier U13A of the dual-channel operational amplifier U13 after passing through the first capacitor C81, the second capacitor C82, and the first resistor R28. The output end and the inverting input end of the first channel operational amplifier U13A form negative feedback to adjust the signal. The adjusted signal flows to the first filter circuit 24 through the output end.

[0059] The electrical impedance imaging signal acquisition circuit of this embodiment sets a dual-channel operational amplifier U13 in the first voltage follower circuit 21 to increase the impedance of the circuit, so that the measurement signal detection circuit 2 is equivalent to an ideal voltmeter, which hardly draws current from the motor of the excitation signal generating circuit 1, so that the voltage of the motor signal will not change significantly, reducing the impact on the motor signal and ensuring the authenticity and integrity of the measurement signal.

[0060] In one embodiment, if Figure 7 As shown, a circuit connection diagram of a first amplitude adjustment circuit 22 is provided. Figure 2 Based on the electrical impedance imaging signal acquisition circuit shown, the first amplitude adjustment circuit 22 includes: a digital potentiometer U14, the control end of the digital potentiometer U14 is electrically connected to the processor 3, the input end of the digital potentiometer U14 is connected to the output end of the programmable amplifier circuit 25, and the output end of the digital potentiometer U14 is connected to the input end of the first differential conversion circuit 26.

[0061] It is understandable that the digital potentiometer of this embodiment can be any type of digital potentiometer. Preferably, the model of the digital potentiometer is AD5271BRMZ.

[0062] The working process of the above-mentioned electrical impedance imaging signal acquisition circuit is as follows: the processor 3 controls the digital potentiometer U14 to adjust the signal output from the output end of the programmable amplifier circuit 25, adjusts the signal to a preset size, and then transmits it to the first differential conversion circuit 26.

[0063] In the electrical impedance imaging signal acquisition circuit of this embodiment, a digital potentiometer U14 is arranged in the first amplitude adjustment circuit 22. The digital potentiometer can be remotely controlled and programmed through a simple digital interface, so that the processor 3 can perform real-time adjustment.

[0064] In one embodiment, if Figure 8 As shown, a schematic diagram of the module structure of an excitation signal generating circuit 1 is provided. Figure 1 Based on the electrical impedance imaging signal acquisition circuit shown, the excitation signal generating circuit 1 includes: a second filtering circuit 11 and a voltage-controlled constant current source circuit 12, the input end of the second filtering circuit 11 is electrically connected to the processor 3, the output end of the second filtering circuit 11 is connected to the input end of the voltage-controlled constant current source circuit 12, and the output end of the voltage-controlled constant current source circuit 12 is electrically connected to the electrode array 4.

[0065] The second filter circuit 11 may be any filter circuit, and the second filter circuit 11 may be an RC filter circuit, the second filter circuit 11 may also be an RL filter circuit, the second filter circuit 11 may also be an LC filter circuit, and the second filter circuit 11 may also be a low-pass filter composed of an operational amplifier. Preferably, the second filter circuit 11 is a low-pass filter, and the structure of the second filter circuit 11 may be the same as that of the first filter circuit 24, or the structure of the second filter circuit 11 may be different from that of the first filter circuit 24.

[0066] Any type of voltage-controlled constant current source can be set in the voltage-controlled constant current source circuit 12. Preferably, a multi-channel operational amplifier is also set in the voltage-controlled constant current source circuit 12, and a current signal is generated by combining the multi-channel operational amplifier and the voltage-controlled constant current source. The current signal is transmitted to the electrode array 4 through an analog switch.

[0067] The working process of the above-mentioned electrical impedance imaging signal acquisition circuit is as follows: the processor 3 outputs a sinusoidal signal through the digital-to-analog conversion module, the sinusoidal signal is filtered by the second filter circuit 11 and then flows to the voltage-controlled constant current source circuit 12, the voltage-controlled constant current source circuit 12 converts the voltage signal into a current signal, and the current signal selects different electrodes under the control of the analog switch.

[0068] The electrical impedance imaging signal acquisition circuit of this embodiment utilizes voltage-controlled constant current to greatly improve the stability and control accuracy of the system, ensuring that the electrodes operate within a safe and controllable current range. The source provides a current signal to the electrode array 4, and the voltage-controlled constant current source ensures that the current on each electrode remains constant.

[0069] like Fig. 9 As shown, a module structure schematic diagram of a reference signal detection circuit is provided.

[0070] In one embodiment, if Fig. 9 As shown in the above Figure 1 On the basis of the electrical impedance imaging signal acquisition circuit shown, the electrical impedance imaging signal acquisition circuit also includes: a reference signal detection circuit 5, the input end of the reference signal detection circuit 5 is electrically connected to the electrode array 4, the output end of the reference signal detection circuit 5 is electrically connected to the processor 3, and a second voltage follower circuit is connected in series in the reference signal detection circuit 5, and the second voltage follower circuit is used to increase the impedance of the reference signal detection circuit 5.

[0071] A sampling resistor is provided in the second voltage follower circuit. The size of the input signal of the second voltage follower circuit is the same as the size of the output signal. The second voltage follower circuit only increases the impedance of the circuit. A single operational amplifier can be provided in the second voltage follower circuit to increase the impedance of the circuit. A multi-channel operational amplifier can also be provided in the second voltage follower circuit, and the impedance of the circuit is increased by a certain operational amplifier in the multi-channel operational amplifier.

[0072] It is understandable that an analog-to-digital converter should be provided between the output end of the reference signal detection circuit 5 and the processor 3 , and the reference signal at the output end of the reference signal detection circuit 5 is transmitted to the processor 3 through the analog-to-digital conversion circuit.

[0073] The working process of the above-mentioned electrical impedance imaging signal acquisition circuit is: the reference signal is acquired by the reference signal detection circuit 5 and then transmitted to the processor 3, the processor 3 digitally demodulates the acquired reference signal and the measurement signal, extracts the phase information and amplitude information of the signal to reconstruct a two-dimensional or three-dimensional image of the resistivity distribution in the body, specifically, demodulates through discrete sequence and discrete Fourier transform.

[0074] The electrical impedance imaging signal acquisition circuit of this embodiment is provided with a second voltage follower circuit in the reference signal detection circuit 5. The second voltage follower circuit can increase the input impedance of the reference signal detection circuit 5, so that the reference signal detection circuit 5 is equivalent to an ideal voltmeter and hardly draws current from the motor of the excitation signal generating circuit 1, so that the voltage of the motor signal does not change significantly, reducing the impact on the motor signal and ensuring the authenticity and integrity of the measurement signal.

[0075] In one embodiment, if Fig. 9 As shown, based on the above embodiment, the reference signal detection circuit 5 also includes: a second amplitude adjustment circuit 52, the input end of the second amplitude adjustment circuit 52 is electrically connected to the second voltage follower circuit, and the output end of the second amplitude adjustment circuit 52 is electrically connected to the processor 3.

[0076] Specifically, a digital potentiometer may be provided in the second amplitude adjustment circuit 52 to adjust the amplitude of the measurement signal, an operational amplifier may be provided in the second amplitude adjustment circuit 52 to adjust the amplitude of the measurement signal, an oscillator may be provided in the second amplitude adjustment circuit 52 to adjust the amplitude of the measurement signal, the structure of the second amplitude adjustment circuit 52 may be the same as that of the first amplitude adjustment circuit 22, or the structure of the second amplitude adjustment circuit 52 may be different from that of the first amplitude adjustment circuit 22. Preferably, the structure of the second amplitude adjustment circuit 52 is the same as that of the first amplitude adjustment circuit 22, and a digital potentiometer is provided in the second amplitude adjustment circuit 52 for adjustment.

[0077] The working process of the electrical impedance imaging signal acquisition circuit is as follows: the first amplitude adjustment circuit 22 adjusts the signal output from the output end of the second voltage follower circuit, adjusts the signal to a preset value, and then inputs it into the processor 3.

[0078] The electrical impedance imaging signal acquisition circuit of this embodiment uses the second amplitude adjustment circuit 52 to adjust the signal, which can compensate for the impedance error caused by the uneven length of the electrode lines in the electrode array 4, and further improve the quality of the reference signal.

[0079] In one embodiment, if Fig. 9As shown, based on the above embodiment, the reference signal detection circuit 5 also includes: a third filtering circuit 53 and a second differential conversion circuit 54, the output end of the second voltage follower circuit is electrically connected to the electrode array 4, the output end of the second voltage follower circuit is connected to the input end of the third filtering circuit 53, the output end of the third filtering circuit 53 is connected to the input end of the second differential conversion circuit 54, and the output end of the second differential conversion circuit 54 is electrically connected to the processor 3.

[0080] The third filter circuit 53 can be any type of filter circuit. The third filter circuit 53 can be an RC filter circuit, the third filter circuit 53 can also be an RL filter circuit, or the third filter circuit 53 can also be an LC filter circuit. The structure of the third filter circuit 53 can be the same as that of the first filter circuit 24, or the structure of the third filter circuit 53 can be different from that of the first filter circuit 24. Preferably, the structure of the third filter circuit 53 is the same as that of the first filter circuit 24.

[0081] The second differential conversion circuit 54 converts the unipolar signal adjusted by the second amplitude adjustment circuit 52 into a bipolar signal, i.e., a differential signal. The differential signal is transmitted to the processor 3 through the analog-to-digital conversion circuit. Preferably, the structure of the second differential conversion circuit 54 is the same as that of the first differential conversion circuit 26.

[0082] Preferably, the circuit connection diagram of the second voltage follower circuit is as follows: Fig.10 shown.

[0083] The working process of the above-mentioned impedance imaging signal acquisition circuit is as follows: the second dual-channel operational amplifier U16 in the second voltage follower circuit obtains the sampling signal through the first sampling resistor R40 and the second sampling resistor R46, forms negative feedback through U16B in the second dual-channel operational amplifier U16, and forms negative feedback again through U16B in the second dual-channel operational amplifier U16. The signal processed by the negative feedback of U16B is filtered by the third filter circuit 53 and then flows to the second differential conversion circuit 54. The second differential conversion circuit 54 converts the unipolar signal adjusted by the first amplitude adjustment circuit 22 into a bipolar signal and transmits it to the analog-to-digital conversion circuit. The analog-to-digital conversion circuit performs analog-to-digital conversion and then transmits it to the processor 3.

[0084] The electrical impedance imaging signal acquisition circuit of this embodiment is provided with a third filtering circuit 53 and a second differential conversion circuit 54 in the reference signal detection circuit 5. The third filtering circuit 53 can filter the signal output by the second voltage follower circuit, thereby improving the quality of the reference signal. The second differential conversion circuit 54 is used to realize high-speed acquisition.

[0085] In one embodiment, a signal acquisition device is provided. The signal acquisition device includes a sensor and the signal acquisition circuit mentioned in any one of the above embodiments. The signal output end of the sensor is connected to the input end of the signal acquisition circuit.

[0086] The above embodiment is only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model is described in detail with reference to the aforementioned embodiment, a person skilled in the art should understand that the technical solution described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solution from the spirit and scope of the technical solution of each embodiment of the utility model, and should be included in the protection scope of the utility model.

Claims

1. An electrical impedance imaging signal acquisition circuit, characterized in that: include: An excitation signal generating circuit and a measurement signal detecting circuit, wherein the input end of the excitation signal generating circuit is electrically connected to a processor, the output end of the excitation signal generating circuit is electrically connected to an electrode array, the input end of the measurement signal detecting circuit is electrically connected to the electrode array, the output end of the measurement signal detecting circuit is electrically connected to the processor, and a first voltage follower circuit is serially arranged in the measurement signal detecting circuit, and the first voltage follower circuit is used to increase the impedance of the measurement signal detecting circuit.

2. The electrical impedance imaging signal acquisition circuit according to claim 1, characterized in that: The measurement signal detection circuit also includes: a first amplitude adjustment circuit, an input end of the first amplitude adjustment circuit is electrically connected to the first voltage follower circuit, and an output end of the first amplitude adjustment circuit is electrically connected to the processor.

3. The electrical impedance imaging signal acquisition circuit according to claim 2, characterized in that: The measurement signal detection circuit also includes: a differential amplifier circuit, a first filter circuit, a programmable amplifier circuit and a first differential conversion circuit. The input end of the differential amplifier circuit is electrically connected to the electrode array, the output end of the differential amplifier circuit is connected to the input end of the first voltage follower circuit, the output end of the first voltage follower circuit is connected to the input end of the first filter circuit, the output end of the first filter circuit is connected to the input end of the programmable amplifier circuit, the control end of the programmable amplifier circuit is electrically connected to the processor, the output end of the programmable amplifier circuit is connected to the input end of the first amplitude adjustment circuit, the control end of the first amplitude adjustment circuit is electrically connected to the processor, the output end of the first amplitude adjustment circuit is connected to the input end of the first differential conversion circuit, and the output end of the first differential conversion circuit is electrically connected to the processor.

4. The electrical impedance imaging signal acquisition circuit according to claim 3, characterized in that: The first voltage follower circuit includes: a first operational amplifier, a first voltage divider branch, and a second voltage divider branch, one end of the first voltage divider branch is connected to the output end of the differential amplifier circuit, the other end of the first voltage divider branch is connected to the non-inverting input end of the first operational amplifier, one end of the second voltage divider branch is connected to the non-inverting input end of the first operational amplifier, the other end of the second voltage divider branch is grounded, the inverting input end of the first operational amplifier is connected to the output end of the first operational amplifier, and the output end of the first operational amplifier is connected to the input end of the first filter circuit.

5. The electrical impedance imaging signal acquisition circuit according to claim 3, characterized in that: The first amplitude adjustment circuit includes: a digital potentiometer, a control end of the digital potentiometer is electrically connected to the processor, an input end of the digital potentiometer is connected to the output end of the programmable amplifier circuit, and an output end of the digital potentiometer is connected to the input end of the first differential conversion circuit.

6. The electrical impedance imaging signal acquisition circuit according to claim 1, characterized in that: The excitation signal generating circuit includes: a second filtering circuit and a voltage-controlled constant current source circuit, the input end of the second filtering circuit is electrically connected to the processor, the output end of the second filtering circuit is connected to the input end of the voltage-controlled constant current source circuit, and the output end of the voltage-controlled constant current source circuit is electrically connected to the electrode array.

7. The electrical impedance imaging signal acquisition circuit according to claim 1, characterized in that: The electrical impedance imaging signal acquisition circuit also includes: a reference signal detection circuit, the input end of the reference signal detection circuit is electrically connected to the electrode array, the output end of the reference signal detection circuit is electrically connected to the processor, and a second voltage follower circuit is connected in series in the reference signal detection circuit, and the second voltage follower circuit is used to increase the impedance of the reference signal detection circuit.

8. The electrical impedance imaging signal acquisition circuit according to claim 7, characterized in that: The reference signal detection circuit further includes: a second amplitude adjustment circuit, an input end of the second amplitude adjustment circuit is electrically connected to the second voltage follower circuit, and an output end of the second amplitude adjustment circuit is electrically connected to the processor.

9. The electrical impedance imaging signal acquisition circuit according to claim 8, characterized in that: The reference signal detection circuit also includes: a third filtering circuit and a second differential conversion circuit, the input end of the second voltage follower circuit is electrically connected to the electrode array, the output end of the second voltage follower circuit is connected to the input end of the third filtering circuit, the output end of the third filtering circuit is connected to the input end of the second differential conversion circuit, and the output end of the second differential conversion circuit is electrically connected to the processor.

10. An electrical impedance imaging signal acquisition device, comprising: The device housing is characterized in that an electrical impedance imaging signal acquisition circuit as described in any one of claims 1 to 9 is arranged in the device housing.

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