Medical dual-range differential circuit and nitric oxide detection device

Abstract

The utility model discloses a medical dual range difference circuit and nitric oxide detection device, and the circuit includes nitric oxide sensor, first amplifier circuit, second amplifier circuit, difference circuit, first amplifier circuit includes first range switching circuit, and second amplifier circuit includes second range switching circuit, and first amplifier circuit, second amplifier circuit respectively through first range switching circuit, second range switching circuit and difference circuit electricity is connected. Improve the measurement accuracy and adaptability of nitric oxide high and low concentration interval, solve the design of single range, use the same amplification ratio, lead to resolution loss seriously when detecting high concentration nNO, influence detection accuracy.

Description

Technical Field

[0001] This utility model relates to the technical field of nitric oxide detection devices, and in particular to a medical dual-range differential circuit and a nitric oxide detection device. Background Technology

[0002] Currently, the mainstream methods for detecting nitric oxide (NO) are chemiluminescence and electrochemical methods. Electrochemical sensors rely on the oxidation or reduction reaction of NO on the electrode surface to generate an electric current, the magnitude of which is directly proportional to its concentration. When exhaled breath comes into contact with the sensor's electrodes, an electrochemical reaction occurs, and the resulting current signal, after amplification and processing, is converted into a NO concentration value for display.

[0003] Most mainstream exhaled nitric oxide (FeNO) detection devices on the market currently use a single-range design, which cannot simultaneously meet the clinical testing needs of exhaled nitric oxide (FeNO, cutoff point 25 ppb) and nasal nitric oxide (nNO, cutoff point 500 ppb). Using the same amplification ratio will result in a significant loss of resolution when detecting high concentrations of nNO, affecting detection accuracy. Summary of the Invention

[0004] Existing medical nitric oxide detection equipment mostly adopts a single-range design and uses the same amplification ratio, which leads to a serious loss of resolution when detecting high concentrations of nNO, affecting the detection accuracy.

[0005] To address the aforementioned issues, a medical dual-range differential circuit and nitric oxide detection device are proposed. By incorporating a first range switching circuit in the first amplifier circuit and a second range switching circuit in the second amplifier circuit, and electrically connecting the output of the first amplifier circuit and the second amplifier circuit to the differential circuit via the first and second range switching circuits respectively, the device can switch to the corresponding range when detecting exhaled nitric oxide (FeNO, cutoff point 25 ppb) and nasal nitric oxide (nNO, cutoff point 500 ppb). This improves the measurement accuracy and adaptability across high and low concentration ranges of nitric oxide and solves the problem of severe resolution loss and reduced detection accuracy when using a single-range design with the same amplification ratio, which leads to high concentrations of nNO.

[0006] In a first aspect, a medical dual-range differential circuit includes:

[0007] Nitric oxide sensor;

[0008] First amplifier circuit;

[0009] Second amplifier circuit;

[0010] Differential circuit;

[0011] The nitric oxide sensor is electrically connected to the input terminals of the first amplifier circuit and the second amplifier circuit, respectively.

[0012] The output terminals of the first amplifier circuit and the second amplifier circuit are respectively electrically connected to the differential circuit.

[0013] The first amplifier circuit includes a first range switching circuit, and the second amplifier circuit includes a second range switching circuit. The first amplifier circuit and the second amplifier circuit are electrically connected to the differential circuit through the first range switching circuit and the second range switching circuit, respectively.

[0014] In conjunction with the medical dual-range differential circuit described in this utility model, in a first possible embodiment, the first amplifier circuit further includes:

[0015] First amplifier;

[0016] The two ends of the first range switching circuit are electrically connected to the negative terminal and the output terminal of the first amplifier, respectively, and are used to switch the feedback resistor to switch the range when detecting different concentrations of nitric oxide.

[0017] In conjunction with the first possible embodiment of this utility model, in the second possible embodiment, the first range switching circuit includes:

[0018] First resistor feedback circuit and second resistor feedback circuit;

[0019] First and second switching switches;

[0020] The first terminal of the first resistor feedback circuit and the first terminal of the second resistor feedback circuit are both connected to the negative terminal of the first amplifier; the second terminals of the first resistor feedback circuit and the second terminal of the second resistor feedback circuit are respectively electrically connected to the second terminal of the first switching switch and the first terminal of the second switching switch.

[0021] The first terminal of the first switching switch is electrically connected to the output terminal of the first amplifier;

[0022] The second terminal of the second switching switch is electrically connected to the differential circuit.

[0023] In a third possible embodiment of the medical dual-range differential circuit described in this utility model, the second amplifier circuit further includes:

[0024] Second amplifier;

[0025] The two ends of the second range switching circuit are electrically connected to the negative terminal and the output terminal of the second amplifier, respectively, and are used to switch the feedback resistor to switch the range when detecting different concentrations of nitric oxide.

[0026] In conjunction with the third possible implementation of this utility model, in the fourth possible implementation, the second range switching circuit includes:

[0027] The third and fourth resistor feedback circuits;

[0028] Third and fourth switching switches;

[0029] The first terminal of the third resistor feedback circuit and the first terminal of the fourth resistor feedback circuit are connected to the negative terminal of the second amplifier; the second terminals of the third resistor feedback circuit and the second terminals of the fourth resistor feedback circuit are respectively electrically connected to the second terminal of the third switch and the first terminal of the fourth switch.

[0030] The first terminal of the third switching switch is electrically connected to the output terminal of the second amplifier;

[0031] The second terminal of the fourth switching switch is electrically connected to the differential circuit.

[0032] In conjunction with the second possible embodiment of this utility model, and in the fifth possible embodiment, the first resistor feedback circuit includes:

[0033] First feedback resistor;

[0034] First filter capacitor;

[0035] The first filter capacitor is connected in parallel with the first feedback resistor;

[0036] The second resistor feedback circuit includes:

[0037] Second feedback resistor;

[0038] Second filter capacitor;

[0039] The second filter capacitor is connected in parallel with the second feedback resistor.

[0040] In conjunction with the fourth possible implementation of this utility model, in the sixth possible implementation, the third resistor feedback circuit includes:

[0041] Third feedback resistor;

[0042] Third filter capacitor;

[0043] The third filter capacitor is connected in parallel with the third feedback resistor;

[0044] The fourth resistor feedback circuit includes:

[0045] Fourth feedback resistor;

[0046] Fourth filter capacitor;

[0047] The fourth filter capacitor is connected in parallel with the fourth feedback resistor.

[0048] In a seventh possible embodiment of the medical dual-range differential circuit described in this utility model, the medical dual-range differential circuit further includes:

[0049] Filtering circuit;

[0050] The first terminal of the filter circuit is electrically connected to the differential circuit;

[0051] The second terminal of the filter circuit is electrically connected to the control circuit.

[0052] In a second aspect, a nitric oxide detection device includes the medical dual-range differential circuit described in the first aspect.

[0053] The present invention provides a medical dual-range differential circuit and nitric oxide detection device. By setting a first range switching circuit in the first amplifier circuit and a second range switching circuit in the second amplifier circuit, and electrically connecting the output of the first amplifier circuit and the second amplifier circuit to the differential circuit through the first and second range switching circuits respectively, it is possible to switch to the corresponding range when detecting exhaled nitric oxide (FeNO, cutoff point 25ppb) and nasal nitric oxide (nNO, cutoff point 500ppb). This improves the measurement accuracy and adaptability of nitric oxide in high and low concentration ranges and solves the problem of severe resolution loss and reduced detection accuracy when using a single range design and the same amplification ratio to detect high concentrations of nNO. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 This is a schematic diagram of the overall structure of the dual-range differential circuit for traditional Chinese medicine of this utility model;

[0056] Figure 2 This is a circuit structure diagram of the dual-range differential circuit for traditional Chinese medicine of this utility model;

[0057] The numbers in the attached diagram represent the following parts: 100 – Nitric oxide sensor, 200 – First amplifier circuit, 300 – Second amplifier circuit, 400 – Differential circuit, 500 – Filter circuit. Detailed Implementation

[0058] The technical solutions of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, other embodiments obtained by those skilled in the art without creative effort are all within the scope of protection of this utility model.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0060] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0061] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0062] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0063] Existing medical nitric oxide detection equipment mostly adopts a single-range design and uses the same amplification ratio, which leads to a serious loss of resolution when detecting high concentrations of nNO, affecting the detection accuracy.

[0064] To address the above problems, a medical dual-range differential circuit 400 and a nitric oxide detection device are proposed.

[0065] Firstly, a medical dual-range differential circuit 400, such as... Figure 1 , Figure 1 This is a schematic diagram of the overall structure of the dual-range differential circuit 400 for traditional Chinese medicine of this utility model; it includes a nitric oxide sensor 100, a first amplifier circuit 200, a second amplifier circuit 300, and a differential circuit 400; the first pin of the nitric oxide sensor 100 is electrically connected to the input terminal of the first amplifier circuit 200; the second pin of the nitric oxide sensor 100 is electrically connected to the input terminal of the second amplifier circuit 300; the output terminals of the first amplifier circuit 200 and the second amplifier circuit 300 are respectively electrically connected to the differential circuit 400; wherein, the first amplifier circuit 200 includes a first range switching circuit, the second amplifier circuit 300 includes a second range switching circuit, and the output terminals of the first amplifier circuit 200 and the second amplifier circuit 300 are respectively electrically connected to the differential circuit 400 through the first range switching circuit and the second range switching circuit.

[0066] In this embodiment, the nitric oxide sensor 100 is used to detect the current generated by the oxidation or reduction reaction of NO on the electrode surface, and the magnitude of the current is proportional to its concentration. When exhaled gas comes into contact with the electrode of the sensor 100, an electrochemical reaction occurs, and the generated current signal is amplified by the first amplifier circuit 200 and the second amplifier circuit 300, and then the voltage difference between the two amplifier circuits is accurately acquired by the differential circuit 400, while suppressing mode interference.

[0067] In this embodiment, the first range switching circuit in the first amplifier circuit 200 and the second range switching circuit in the second amplifier circuit 300 can be used to switch the detection ranges for exhaled nitric oxide (FeNO, cutoff point 25ppb) and nasal nitric oxide (nNO, cutoff point 500ppb), respectively.

[0068] In one possible implementation, such as Figure 2 , Figure 2 This is a circuit structure diagram of the dual-range differential circuit 400 for traditional Chinese medicine of this utility model; the first amplifier circuit 200 also includes a first amplifier; the two ends of the first range switching circuit are electrically connected to the negative terminal and the output terminal of the first amplifier respectively, and are used to switch the feedback resistor when detecting different concentrations of nitric oxide, so as to switch the range.

[0069] In one possible implementation, such as Figure 2The first range switching circuit includes a first resistive feedback circuit and a second resistive feedback circuit; a first switching switch U2A and a second switching switch U2B; the first terminal of the first resistive feedback circuit and the first terminal of the second resistive feedback circuit are connected to the negative terminal of the first amplifier; the second terminals of the first resistive feedback circuit and the second terminals of the second resistive feedback circuit are electrically connected to the second terminal of the first switching switch U2A and the first terminal of the second switching switch U2B, respectively; the first terminal of the first switching switch U2A is electrically connected to the output terminal of the first amplifier; and the second terminal of the second switching switch U2B is electrically connected to the differential circuit 400.

[0070] In one possible implementation, such as Figure 2 The first resistor feedback circuit includes a first feedback resistor, a first filter capacitor, and the first filter capacitor and the first feedback resistor are connected in parallel; the second resistor feedback circuit includes a second feedback resistor and a second filter capacitor; the second filter capacitor and the second feedback resistor are connected in parallel.

[0071] In the embodiments of this application, such as Figure 2 The nitric oxide sensor 100 includes an AUX pin, a SEN pin, a REF pin, and a CNT pin, wherein the AUX pin is electrically connected to the first amplifier circuit 200, and the SEN pin is electrically connected to the second amplifier circuit 300.

[0072] The first resistor feedback circuit includes a resistor R60 (first feedback resistor) and a capacitor C38 (first filter capacitor), with the resistor R60 and the capacitor C38 connected in parallel.

[0073] The first resistor feedback circuit includes resistor R64 (second feedback resistor) and capacitor C39 (second filter capacitor), with resistor R64 and capacitor C39 connected in parallel;

[0074] The first resistor feedback circuit and the second resistor feedback circuit are connected in parallel across the first amplifier.

[0075] The differential circuit 400 includes a differential processing chip U17;

[0076] The first terminal 10 of the first switching switch U2A, the second terminals 9 and 2, the first terminals 7 and 4 of the second switching switch U2B, the second terminal 6, and the second terminal 6 of the second switching switch U2B are electrically connected to the negative input terminal IN- of the differential processing chip U17 after passing through the voltage regulating resistor R63 and the filter capacitor C40.

[0077] In one possible implementation, the second amplifier circuit 300 further includes a second amplifier; the two ends of the second range switching circuit are electrically connected to the negative terminal and the output terminal of the second amplifier, respectively, for switching the feedback resistor when detecting different concentrations of nitric oxide, so as to switch the range.

[0078] In one possible implementation, such as Figure 2 The second range switching circuit includes: a third resistance feedback circuit and a fourth resistance feedback circuit; a third switching switch U1A and a fourth switching switch U1B; the first terminal of the third resistance feedback circuit and the first terminal of the fourth resistance feedback circuit are connected to the negative terminal of the second amplifier; the second terminals of the third resistance feedback circuit and the second terminals of the fourth resistance feedback circuit are electrically connected to the second terminal of the third switching switch U1A and the first terminal of the fourth switching switch U1B, respectively; the first terminal of the third switching switch U1A is electrically connected to the output terminal of the second amplifier; and the second terminal of the fourth switching switch U1B is electrically connected to the differential circuit 400.

[0079] In one possible implementation, such as Figure 2 The third resistor feedback circuit includes a third feedback resistor and a third filter capacitor; the third filter capacitor and the third feedback resistor are connected in parallel. The fourth resistor feedback circuit includes a fourth feedback resistor and a fourth filter capacitor; the fourth filter capacitor and the fourth feedback resistor are connected in parallel.

[0080] The third resistor feedback circuit includes resistor R66 (third feedback resistor) and capacitor C42 (third filter capacitor), with resistor R66 and capacitor C42 connected in parallel.

[0081] The fourth resistor feedback circuit includes resistor R67 (fourth feedback resistor) and capacitor C43 (fourth filter capacitor), with resistor R67 and capacitor C43 connected in parallel;

[0082] The third and fourth resistor feedback circuits are connected in parallel across the second amplifier.

[0083] The first terminal 10 of the third switching switch U1A, the second terminals 9 and 2, the first terminals 7 and 4 of the fourth switching switch U1B, the second terminal 6, and the second terminal 6 of the fourth switching switch U1B are electrically connected to the positive input terminal IN+ of the differential processing chip U17 after passing through the voltage regulating resistor R69 and the filter capacitor C47.

[0084] In this embodiment, the nitric oxide sensor 100 is a four-electrode electrochemical sensor 100, and its range switching is shown in Table 1.

[0085] Table 1. Range switching modes of the four-electrode electrochemical sensor 100

[0086]

[0087] like Figure 2In this embodiment, VOut(FeNO) = 402K*IR and VOut(nNO) = 100K*IR, with a resolution difference of four times. When the patient selects different measurement modes, the host computer sends commands to the MCU to select different amplification ratios, thus ensuring maximum resolution. It is important to note here that a small leakage current device for analog switching should be selected.

[0088] To further illustrate, consider the following example: the sensitivity of sensor 100 (0.7-1.7 nA / ppb).

[0089] When testing FeNO, its output voltage is V FeNO=(0.7~1.7)*10-9A / ppb*402*103Ω=(2.8~6.8)mv / ppb. With the maximum range of 300ppb, the maximum output voltage is 2.04V.

[0090] When testing nNO, its output voltage is V nNO=(0.7-1.7)*10-9A / ppb*100*103Ω=(0.7-1.7)mV / ppb. With the maximum range of 2000ppb, its maximum output voltage is 3.4V, which is a reasonable design.

[0091] In one possible implementation, the medical dual-range differential circuit 400 further includes a filter circuit 500; a first terminal of the filter circuit 500 is electrically connected to the differential circuit 400; and a second terminal of the filter circuit 500 is electrically connected to the control circuit.

[0092] In this embodiment, the second-order active filter topology of the Sallen-key filter with a cutoff frequency of 0.1 Hz requires only one operational amplifier and a small number of resistors and capacitors, making it easy to design and implement. It features high input impedance and low output impedance, avoiding load effects on the preceding circuitry while effectively driving the subsequent circuitry.

[0093] In this embodiment, by setting a first range switching circuit in the first amplifier circuit 200 and a second range switching circuit in the second amplifier circuit 300, and electrically connecting the output of the first amplifier circuit 200 and the second amplifier circuit 300 to the differential circuit 400 through the first and second range switching circuits respectively, it is possible to switch to the corresponding range when detecting exhaled nitric oxide (FeNO, cutoff point 25ppb) and nasal nitric oxide (nNO, cutoff point 500ppb). This improves the measurement accuracy and adaptability of nitric oxide in high and low concentration ranges and solves the problem of severe resolution loss and reduced detection accuracy when using a single range design and the same amplification ratio to detect high concentrations of nNO.

[0094] In a second aspect, a nitric oxide detection device includes a medical dual-range differential circuit 400 as described in the first aspect.

[0095] The present invention provides a medical dual-range differential circuit 400 and a nitric oxide detection device. By setting a first range switching circuit in the first amplifier circuit 200 and a second range switching circuit in the second amplifier circuit 300, and electrically connecting the output of the first amplifier circuit 200 and the second amplifier circuit 300 to the differential circuit 400 through the first and second range switching circuits respectively, it is possible to switch to the corresponding range when detecting exhaled nitric oxide (FeNO, cutoff point 25ppb) and nasal nitric oxide (nNO, cutoff point 500ppb). This improves the measurement accuracy and adaptability of nitric oxide in high and low concentration ranges and solves the problem of severe resolution loss and reduced detection accuracy when using a single range design and the same amplification ratio to detect high concentrations of nNO.

[0096] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A medical dual-range differential circuit, characterized in that, include: Nitric oxide sensor; First amplifier circuit; Second amplifier circuit; Differential circuit; The nitric oxide sensor is electrically connected to the input terminals of the first amplifier circuit and the second amplifier circuit, respectively. The output terminals of the first amplifier circuit and the second amplifier circuit are respectively electrically connected to the differential circuit. The first amplifier circuit includes a first range switching circuit, and the second amplifier circuit includes a second range switching circuit. The first amplifier circuit and the second amplifier circuit are electrically connected to the differential circuit through the first range switching circuit and the second range switching circuit, respectively.

2. The medical dual-range differential circuit according to claim 1, characterized in that, The first amplifier circuit also includes: First amplifier; The two ends of the first range switching circuit are electrically connected to the negative terminal and the output terminal of the first amplifier, respectively, and are used to switch the feedback resistor to switch the range when detecting different concentrations of nitric oxide.

3. The medical dual-range differential circuit according to claim 2, characterized in that, The first range switching circuit includes: First resistor feedback circuit and second resistor feedback circuit; First and second switching switches; The first terminal of the first resistor feedback circuit and the first terminal of the second resistor feedback circuit are both connected to the negative terminal of the first amplifier; the second terminals of the first resistor feedback circuit and the second terminal of the second resistor feedback circuit are respectively electrically connected to the second terminal of the first switching switch and the first terminal of the second switching switch. The first terminal of the first switching switch is electrically connected to the output terminal of the first amplifier; The second terminal of the second switching switch is electrically connected to the differential circuit.

4. The medical dual-range differential circuit according to claim 1, characterized in that, The second amplifier circuit also includes: Second amplifier; The two ends of the second range switching circuit are electrically connected to the negative terminal and the output terminal of the second amplifier, respectively, and are used to switch the feedback resistor to switch the range when detecting different concentrations of nitric oxide.

5. The medical dual-range differential circuit according to claim 4, characterized in that, The second range switching circuit includes: The third and fourth resistor feedback circuits; Third and fourth switching switches; The first terminal of the third resistor feedback circuit and the first terminal of the fourth resistor feedback circuit are connected to the negative terminal of the second amplifier; the second terminals of the third resistor feedback circuit and the second terminals of the fourth resistor feedback circuit are respectively electrically connected to the second terminal of the third switch and the first terminal of the fourth switch. The first terminal of the third switching switch is electrically connected to the output terminal of the second amplifier; The second terminal of the fourth switching switch is electrically connected to the differential circuit.

6. The medical dual-range differential circuit according to claim 3, characterized in that, The first resistor feedback circuit includes: First feedback resistor; First filter capacitor; The first filter capacitor is connected in parallel with the first feedback resistor; The second resistor feedback circuit includes: Second feedback resistor; Second filter capacitor; The second filter capacitor is connected in parallel with the second feedback resistor.

7. The medical dual-range differential circuit according to claim 5, characterized in that, The third resistor feedback circuit includes: Third feedback resistor; Third filter capacitor; The third filter capacitor is connected in parallel with the third feedback resistor; The fourth resistor feedback circuit includes: Fourth feedback resistor; Fourth filter capacitor; The fourth filter capacitor is connected in parallel with the fourth feedback resistor.

8. The medical dual-range differential circuit according to any one of claims 1-7, characterized in that, The medical dual-range differential circuit also includes: Filtering circuit; The first terminal of the filter circuit is electrically connected to the differential circuit; The second terminal of the filter circuit is electrically connected to the control circuit.

9. A nitric oxide detection device, characterized in that, Includes the medical dual-range differential circuit as described in any one of claims 1-8.

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