Low-cost portable NDIR exhaled gas acetone detection device and application method thereof

Abstract

The invention discloses a low-cost portable NDIR (Non-Dispersive Infra-Red) exhaled gas acetone detection device and an application method thereof, a constant current driving module is used for guaranteeing the stability of a base line, an infrared light source module is used for providing a stable intermediate infrared radiation source, an infrared light source is used for covering an acetone characteristic absorption wave band, and a gas absorption pool module is used for improving the detection sensitivity; the dual-channel infrared detection module is used for accurately capturing a light intensity attenuation signal of an acetone characteristic absorption wave band and realizing differential detection and anti-interference compensation, and the signal acquisition and amplification module is used for extracting an effective component related to the acetone concentration from a weak signal output by a pyroelectric detector; the upper computer processing module is used for performing differential operation and concentration inversion and calculating the concentration value of acetone in exhaled air; by fusing an MEMS infrared light source, a multiple reflection light path and a two-channel differential detection technology, high-sensitivity detection is realized, and a popular portable solution is provided for early screening of diabetes mellitus metabolic disorder and lung cancer.

Description

Technical Field

[0001] The present invention relates to the technical field of medical equipment, and in particular to a low-cost portable NDIR exhaled breath acetone detection device and an application method thereof. Background Art

[0002] In recent years, exhaled gas analysis technology, as an emerging non-invasive detection method, has received widespread attention in the field of early disease screening due to its advantages such as rapidity and ease of operation. Studies have shown that human exhaled breath contains a variety of volatile organic compounds, among which acetone, as an important product of fat metabolism, its concentration changes can reflect abnormal metabolic status in the body. In diabetic patients, the exhaled acetone concentration is generally higher than that of normal people. Literature shows that the exhaled acetone concentration of patients with type 1 diabetes can reach 2.2 to 22 ppm, and that of patients with type 2 diabetes is generally 1.76 to 9 ppm, while the average exhaled acetone concentration of healthy non-fasting individuals is about 0.4 ppm.

[0003] In the field of lung cancer, studies have reported that acetone concentrations in the exhaled breath of patients are also higher than those in the normal population. These studies suggest that exhaled acetone concentrations vary significantly in both diabetes and lung cancer, making it a potential noninvasive biomarker. Highly sensitive acetone detection technology will facilitate early identification and screening of both diseases. Therefore, this paper proposes a low-cost, portable NDIR exhaled breath acetone detection device and its application method to address the challenges of existing technologies. Summary of the Invention

[0004] In response to the above problems, the purpose of the present invention is to propose a low-cost portable NDIR exhaled breath acetone detection device and its application method. The low-cost portable NDIR exhaled breath acetone detection device and its application method integrate MEMS infrared light source, multiple reflection optical path and dual-channel differential detection technology, while significantly reducing system cost and volume, achieving high-sensitivity detection. The reference channel calibration and dehumidification filtration module effectively improve the detection stability. It has the advantages of being non-invasive, fast and easy to operate. It is particularly suitable for primary medical and home scenarios, providing a popular portable solution for early screening of diabetic metabolic disorders and lung cancer, which can significantly increase the screening coverage of high-risk populations and promote the early diagnosis and treatment of major diseases.

[0005] To achieve the objectives of the present invention, the present invention is implemented through the following technical solutions: a low-cost portable NDIR exhaled breath acetone detection device and an application method thereof, comprising a constant current drive module, an infrared light source module, a gas absorption cell module, a dual-channel infrared detection module, a signal acquisition and amplification module, and a host computer processing module. The constant current drive module is configured by an analog feedback circuit to ensure that the luminous intensity does not change with power supply fluctuations, thereby ensuring baseline stability. The infrared light source module is configured to provide a stable mid-infrared radiation source, using the infrared light source to cover the characteristic absorption band of acetone. The gas absorption cell module is configured to achieve multiple interactions between the gas sample and the infrared light, thereby improving detection sensitivity. The dual-channel infrared detection module is configured to accurately capture the light intensity attenuation signal in the characteristic absorption band of acetone, achieving differential detection and anti-interference compensation. The signal acquisition and amplification module is configured to extract effective components related to the acetone concentration from the weak signal output by the pyroelectric detector. The host computer processing module is configured to perform differential operations and concentration inversion on the signals output by the dual-channel infrared detection module to calculate the concentration of acetone in the exhaled breath.

[0006] A further improvement is that the gas absorption cell module includes a gas absorption cell unit and a filtration and dehumidification unit. The gas absorption cell unit is used to achieve efficient infrared reflection and increase the effective optical path, and the filtration and dehumidification unit is used to eliminate interference from water vapor and particulate matter.

[0007] A further improvement is that the gas absorption cell unit is designed as a cavity structure with a highly reflective inner wall, and the inner wall is made of gold-plated metal.

[0008] A further improvement is that the dual-channel infrared detection module includes a measurement channel unit and a reference channel unit, the measurement channel unit is used to specifically capture the acetone absorption signal, and the reference channel unit is used to dynamically monitor background noise and system errors.

[0009] A further improvement is that the measurement channel unit is equipped with a 3.3 μm narrowband filter to cover the main absorption peak of acetone, and the reference channel unit is equipped with a 3.95 μm filter to monitor background noise and light source fluctuations.

[0010] The following steps are involved:

[0011] Step 1: Sample collection and pretreatment. Before sampling, the subject must maintain a normal breathing rhythm, take 3 to 5 deep breaths, and then exhale continuously for 6 to 8 seconds through a dedicated mouthpiece. The exhaled gas is processed by a built-in filtration and dehumidification unit to remove particulate matter and moisture. The pretreated dry gas enters the gas absorption cell module and completes 20 to 30 optical reflections in the gold-plated reflection cavity.

[0012] Step 2: Light source control: start the infrared light source module and constant current drive module, and stabilize the light source temperature at 850±5℃ through PID control;

[0013] Step 3: Dual-channel infrared detection: Use the 3.3μm narrowband filter in the measurement channel unit of the dual-channel infrared detection module to capture the acetone characteristic absorption signal, and use the 3.95μm filter in the reference channel unit to monitor background noise and light source fluctuations;

[0014] Step 4: Signal processing and analysis: The host computer processing module performs differential operation and concentration inversion on the signal output by the dual-channel infrared detection module.

[0015] A further improvement is that: the host computer processing module receives two voltage signals of the measurement channel unit and the reference channel unit, which are V GS With V REF , the dual-channel model derivation formula is:

[0016] V GS =λ G (T,t)·I0(T,t)·e -kLc

[0017] V REF =λ R (T,t)·I0(T,t)

[0018] The λ G ,λ R are the photoelectric sensitivity coefficients of the detector, and I0 is the light source intensity. Due to temperature fluctuations and self-heating effects of the MEMS light source, I0 changes over time. To suppress this instability, the ratio of the two channels is used to eliminate the influence of I0, resulting in:

[0019]

[0020] Where Q = λ G / λ R is the ratio of the detector's fixed structure factor, which is known through calibration at the factory. From this, the gas concentration can be solved:

[0021]

[0022] The beneficial effects of the present invention are: by integrating MEMS infrared light source, multiple reflection optical path and dual-channel differential detection technology, the present invention achieves high-sensitivity detection while significantly reducing system cost and volume, and effectively improves detection stability through reference channel calibration and dehumidification filtration module. It has the advantages of being non-invasive, fast and easy to operate, and is particularly suitable for primary medical care and home scenarios. It provides a popular and portable solution for early screening of diabetic metabolic abnormalities and lung cancer, can significantly improve the screening coverage of high-risk populations, and promote early diagnosis and treatment of major diseases. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a system architecture diagram of the present invention;

[0024] Figure 2 is a flow chart of the steps of the present invention;

[0025] Figure 3 It is a composition diagram of the gas absorption cell of the present invention;

[0026] Figure 4 is the acetone absorption spectrum of the present invention; DETAILED DESCRIPTION

[0027] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the examples. The examples are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0028] Lung cancer and diabetes are two major diseases that currently pose a serious threat to human health. As a malignant tumor with a high incidence and mortality rate worldwide, early screening of lung cancer is of great significance to improving the survival rate of patients. Currently, the commonly used lung cancer screening methods in clinical practice are mainly imaging methods such as low-dose spiral CT. Although they have a certain sensitivity, they have problems such as high equipment cost, high radiation risk and high false positive rate, which are not suitable for large-scale initial screening of healthy people. The diagnosis and management of diabetes rely on frequent blood glucose monitoring, and blood sampling is often used. It has the disadvantages of high invasiveness, poor compliance, and complicated detection process. Therefore, the development of a non-invasive, portable, low-cost early screening method for the disease has become a clinical urgent need.

[0029] Example 1

[0030] Based on this, according to Figure 1 、 Figure 3 、 Figure 4 As shown, this embodiment provides a low-cost portable NDIR exhaled breath acetone detection device, including a constant current drive module, an infrared light source module, a gas absorption cell module, a dual-channel infrared detection module, a signal acquisition and amplification module, and a host computer processing module. The constant current drive module is used to ensure that the luminous intensity does not change with power supply fluctuations through an analog feedback circuit, thereby ensuring the stability of the baseline. The infrared light source module is used to provide a stable mid-infrared radiation source, and the infrared light source is used to cover the characteristic absorption band of acetone. The gas absorption cell module is used to realize multiple interactions between the gas sample and the infrared light to improve the detection sensitivity. The constant current drive adjusts the current in real time through a closed-loop feedback circuit, and at the same time cooperates with the PID algorithm to accurately stabilize the light source temperature at 850±5°C, ensuring that the broadband mid-infrared radiation emitted by the light source covers the 3.3μm characteristic absorption peak of acetone and suppressing the wavelength drift caused by self-heating or ambient temperature changes of the light source.

[0031] The gas absorption cell module includes a gas absorption cell unit and a filtration and dehumidification unit. The gas absorption cell unit is used to achieve efficient infrared reflection and improve the effective optical path. The filtration and dehumidification unit is used to eliminate interference from water vapor and particulate matter. The gas absorption cell unit is designed as a cavity structure with a highly reflective inner wall, and the inner wall is made of gold-plated metal. After the subject exhales for 6 to 8 seconds at a normal breathing rhythm through a special mouthpiece, the exhaled gas first enters the filtration and dehumidification unit, intercepts particulate matter with a diameter greater than 1μm through multiple layers of filter membranes, and removes water vapor through hygroscopic materials, so that the gas humidity is reduced to <5% RH to avoid water vapor interfering with the acetone absorption signal in subsequent detection.

[0032] The dual-channel infrared detection module is used to accurately capture the light intensity attenuation signal of the characteristic absorption band of acetone, realize differential detection and anti-interference compensation, the signal acquisition and amplification module is used to extract the effective components related to the acetone concentration from the weak signal output by the pyroelectric detector, and the host computer processing module is used to perform differential operation and concentration inversion on the signal output by the dual-channel infrared detection module to calculate the concentration value of acetone in the exhaled breath. The dual-channel infrared detection module includes a measurement channel unit and a reference channel unit. The measurement channel unit is used to specifically capture the acetone absorption signal, and the reference channel unit is used to dynamically monitor the background noise and System error: The measurement channel unit is equipped with a 3.3μm narrowband filter to cover the main absorption peak of acetone, and the reference channel unit is equipped with a 3.95μm filter to monitor background noise and light source fluctuations. After the infrared light passes through the absorption cell, the optical signal carrying gas absorption information is received by the dual-channel infrared detection module. The measurement channel unit uses a 3.3μm narrowband filter to selectively transmit light near the acetone absorption peak, and the pyroelectric detector converts it into an electrical signal. The reference channel unit uses a 3.95μm filter to avoid the acetone absorption band to capture the light source's own fluctuations and environmental background noise, and output a reference signal.

[0033] Example 2

[0034] according to Figure 2 、 Figure 3 、 Figure 4 As shown, this embodiment provides an application method of a low-cost portable NDIR exhaled breath acetone detection device, comprising the following steps:

[0035] Step 1: Sample collection and pretreatment. Before sampling, the subject must maintain a normal breathing rhythm, take three deep breaths, and then exhale for 6 seconds through a dedicated mouthpiece. The exhaled gas is processed by a built-in filter and dehumidification unit to remove particulate matter and moisture. The pretreated dry gas enters the gas absorption cell module and completes 25 optical reflections in the gold-plated reflective cavity.

[0036] Step 2: Light source control: start the infrared light source module and constant current drive module, and stabilize the light source temperature at 850°C through PID control;

[0037] Step 3: Dual-channel infrared detection: Use the 3.3μm narrowband filter in the measurement channel unit of the dual-channel infrared detection module to capture the acetone characteristic absorption signal, and use the 3.95μm filter in the reference channel unit to monitor background noise and light source fluctuations;

[0038] Step 4: Signal processing and analysis: The host computer processing module performs differential operation and concentration inversion on the signal output by the dual-channel infrared detection module.

[0039] The host computer processing module receives two voltage signals from the measurement channel unit and the reference channel unit, which are V GS With V REF , the dual-channel model derivation formula is:

[0040] V GS =λ G (T,t)·I0(T,t)·e -kLc

[0041] V REF =λ R (T,t)·I0(T,t)

[0042] λ G ,λ R are the photoelectric sensitivity coefficients of the detector, and I0 is the light source intensity. Due to temperature fluctuations and self-heating effects of the MEMS light source, I0 changes over time. To suppress this instability, the ratio of the two channels is used to eliminate the influence of I0, resulting in:

[0043]

[0044] Where Q = λ G / λ R is the ratio of the detector's fixed structure factor, which is known through calibration at the factory. From this, the gas concentration can be solved:

[0045]

[0046] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A low-cost portable NDIR exhaled breath acetone detection device, characterized by: The system includes a constant current drive module, an infrared light source module, a gas absorption cell module, a dual-channel infrared detection module, a signal acquisition and amplification module, and a host computer processing module. The constant current drive module is configured by an analog feedback circuit to ensure that the luminous intensity does not change with power supply fluctuations, thereby ensuring baseline stability. The infrared light source module is configured to provide a stable mid-infrared radiation source, and the infrared light source is used to cover the characteristic absorption band of acetone. The gas absorption cell module is configured to realize multiple interactions between the gas sample and the infrared light, thereby improving detection sensitivity. The dual-channel infrared detection module is configured to accurately capture the light intensity attenuation signal of the characteristic absorption band of acetone, thereby realizing differential detection and anti-interference compensation. The signal acquisition and amplification module is configured to extract effective components related to the acetone concentration from the weak signal output by the pyroelectric detector. The host computer processing module is configured to perform differential operations and concentration inversion on the signals output by the dual-channel infrared detection module, thereby calculating the concentration value of acetone in the exhaled breath.

2. A low-cost portable NDIR exhaled breath acetone detection device according to claim 1, characterized in that: The gas absorption cell module includes a gas absorption cell unit and a filtration and dehumidification unit. The gas absorption cell unit is used to achieve efficient infrared reflection and increase the effective optical path, and the filtration and dehumidification unit is used to eliminate interference from water vapor and particulate matter.

3. A low-cost portable NDIR exhaled breath acetone detection device according to claim 2, characterized in that: The gas absorption cell unit is designed as a cavity structure with a highly reflective inner wall, and the inner wall is made of gold-plated metal.

4. A low-cost portable NDIR exhaled breath acetone detection device according to claim 1, characterized in that: The dual-channel infrared detection module includes a measurement channel unit and a reference channel unit. The measurement channel unit is used to specifically capture the acetone absorption signal, and the reference channel unit is used to dynamically monitor background noise and system errors.

5. A low-cost portable NDIR exhaled breath acetone detection device according to claim 4, characterized in that: The measurement channel unit is configured with a 3.3 μm narrowband filter to cover the main absorption peak of acetone, and the reference channel unit is configured with a 3.95 μm filter to monitor background noise and light source fluctuation.

6. A method for using a low-cost portable NDIR exhaled breath acetone detection device, comprising the following steps: Step 1: Sample collection and pretreatment. Before sampling, the subject must maintain a normal breathing rhythm, take 3 to 5 deep breaths, and then exhale continuously for 6 to 8 seconds through a dedicated mouthpiece. The exhaled gas is processed by a built-in filtration and dehumidification unit to remove particulate matter and moisture. The pretreated dry gas enters the gas absorption cell module and completes 20 to 30 optical reflections in the gold-plated reflection cavity. Step 2: Light source control: start the infrared light source module and constant current drive module, and stabilize the light source temperature at 850±5℃ through PID control; Step 3: Dual-channel infrared detection: Use the 3.3μm narrowband filter in the measurement channel unit of the dual-channel infrared detection module to capture the acetone characteristic absorption signal, and use the 3.95μm filter in the reference channel unit to monitor background noise and light source fluctuations; Step 4: Signal processing and analysis: The host computer processing module performs differential operation and concentration inversion on the signal output by the dual-channel infrared detection module.

7. The application method of a low-cost portable NDIR exhaled breath acetone detection device according to claim 6, characterized in that: The host computer processing module receives two voltage signals of the measurement channel unit and the reference channel unit, respectively V GS With V REF , the dual-channel model derivation formula is: V GS λ G (T,t)·I0(T,t)·e -kLc V REF =λ R (T,t)·I0(T,t) The λ G ,λ R are the photoelectric sensitivity coefficients of the detector, and I0 is the light source intensity. Due to the temperature fluctuation and self-heating effect of the MEMS light source, I0 changes with time. To suppress this instability, the ratio of the two channels is used to eliminate the influence of I0, and the result is: where Q = λ G / λ R is the ratio of the detector's fixed structure factor, which is known through calibration at the factory. From this, the gas concentration can be solved:

Images