Metabolism detection device and method based on adjustable mixing tank

Abstract

The invention provides a metabolism detection device and method based on an adjustable mixing tank. The metabolism detection device is composed of a human body breathing gas collection module, an expired gas concentration detection module, a calibration gas supply module, an electromagnetic valve switching module, a control module and a computer. The human body breathing gas collecting module is used for separating breathing gas, providing a breathing channel, detecting the expiration flow and collecting and physically averaging the gas; the expired gas concentration detection module is used for detecting oxygen and carbon dioxide concentrations of gas to be detected; the calibration gas supply module provides calibration gas; the electromagnetic valve switching module provides gas switching selection; the control module is responsible for controlling each component and acquiring signals; and the computer is responsible for data processing, index calculation and result display. The detection method comprises the following steps: firstly calibrating the concentration, then carrying out a motion or resting metabolism test based on spontaneous respiration, and finally calculating the metabolism index according to the measured gas concentration and flow data. The method can be applied to metabolism detection scenes of resting and different exercise intensities, and is reliable in test and simple in engineering realization.

Description

Technical Field

[0001] This invention belongs to the field of human energy metabolism detection, and particularly relates to a metabolic detection device and method based on an adjustable mixing tank. Background Technology

[0002] Exercise metabolism, an indicator reflecting energy expenditure during exercise, is fundamental for developing exercise prescriptions, controlling weight, and assessing cardiopulmonary function. In clinical medicine, exercise metabolism (primarily through the cardiopulmonary exercise test, CPET) is widely used for the diagnosis, assessment, and intervention of cardiopulmonary diseases, serving as a crucial bridge connecting basic physiological mechanisms with clinical symptoms. Human metabolic testing is significant in clinical nutrition, intensive care, and sports health. By measuring oxygen consumption and carbon dioxide production in respiratory gases, it is possible to accurately assess the body's energy metabolism level and nutritional needs, providing a scientific basis for disease diagnosis, rehabilitation guidance, and the development of personalized nutrition plans. Indirect calorimetry is considered the "gold standard" for metabolic testing; however, existing testing devices still need improvement in terms of adaptability, ease of operation, real-time performance, and detection accuracy, particularly in meeting the needs of different populations and various application scenarios. The invention application titled "A Device and Method for Detecting Human Respiratory Heat Metabolism Based on a Piston Cylinder" (publication number CN119423738B) utilizes a piston cylinder to achieve proportional sampling and physical mixing of individual breaths related to human respiratory metabolism. A constant pressure and constant current output is then sent to a gas concentration analysis module, effectively reducing the requirements for the dynamic performance of the gas concentration sensor and making it suitable for both spontaneous breathing and mechanical ventilation detection scenarios. However, this approach suffers from drawbacks such as an unadjustable mixing chamber volume, complex gas path structure, significant dead space and airflow resistance, and a high risk of leakage. These limitations make it difficult to flexibly adjust for different testing needs and also affect the system's safety and comfort.

[0003] Existing technologies such as the head-covering method, which uses an open-faced head cover for air collection, are unsuitable for sports scenarios; the breath-by-breath method faces significant engineering challenges due to high breathing resistance during exercise and the need for precise synchronization of concentration and flow signals; the metabolic chamber method suffers from high technical barriers, system complexity, high cost, and insufficient real-time performance and practicality. In short, existing methods for human metabolic detection fall short of the requirements for portable, accurate, and dynamic monitoring of metabolic parameters during exercise. Specific challenges include:

[0004] Real-time and accurate measurement of respiratory flow and gas composition is challenging; the detection system has a complex structure and is inconvenient to install and operate; and the technical difficulty of collecting mixed exhaled air and ensuring signal stability during exercise is high.

[0005] The mixing tank has a fixed volume, which cannot be adjusted to meet different experimental needs, affecting the homogenization effect and the representativeness of the samples; the gas path has a dead space and large resistance: the structural design is not fully optimized, causing gas retention and flow resistance, which affects the test sensitivity; the signal calibration is not perfect: there is a time delay difference between flow rate and concentration sampling, and there is a lack of efficient time alignment calibration methods, resulting in data errors; the system is complex and cumbersome to operate: the structure and operation process are not optimized, which reduces the applicability and promotion of the test scenarios. Summary of the Invention

[0006] To address the aforementioned shortcomings, the purpose of this invention is to provide a metabolic detection device and method based on an adjustable mixing chamber. This device and method achieves adjustable mixing chamber volume, adaptability to different testing needs, optimized gas path structure, reduced dead space and resistance, lower leakage risk, and low requirements for the dynamic performance of gas concentration sensors. It enables high-safety and high-comfort detection of human energy metabolism. The specific technical solution is as follows:

[0007] A metabolic detection device based on an adjustable mixing tank comprises a human respiratory gas collection module, an exhaled gas concentration detection module, a calibration gas supply module, a solenoid valve switching module, a control module, and a computer. The human respiratory gas collection module separates the subject's respiratory gases, provides a respiratory pathway, detects exhaled gas flow, and collects and physically averages the subject's exhaled gases. The exhaled gas concentration detection module detects the concentration of gas components in the test gas, including oxygen and carbon dioxide concentrations. The calibration gas supply module provides calibration gas for concentration calibration to the exhaled gas concentration detection module; this is achieved by supplying high-pressure calibration gas from a high-pressure gas source after pressure reduction and depressurization. The solenoid valve switching module provides gas switching options for the exhaled gas concentration detection module, allowing selective supply between the subject's exhaled gases in the human respiratory gas collection module, the high-pressure gas source in the calibration gas supply module, and ambient gas. The control module controls the motors, solenoid valves, sensors, and other components in the device and acquires signals. The computer is used for data processing and analysis, index calculation, result display, and human-computer interaction.

[0008] A method for detecting human metabolic capacity based on the above-mentioned device includes the following steps:

[0009] Step 1: Perform gas concentration calibration for the sensor and flow rate / volume calibration for the flow sensor. During the calibration of the first set of calibration gas concentrations, enable the first and second solenoid valves, switching the gas flow path to the NC-COM pathway. Close the second high-pressure calibration gas source and open the first high-pressure calibration gas source. The calibration gas passes sequentially through the first pressure reducing valve, the second solenoid valve, and the first solenoid valve to the sensor in the gas concentration analysis module, providing the first set of calibration gas flow paths. After gas flow and collection of the average gas concentration over a period of time, complete the sensor's range calibration. Then, perform the calibration of the second set of calibration gas concentrations. When the first and third solenoid valves are enabled, the gas flow path switches to the NC-COM path; when the second solenoid valve is disabled, the gas flow path switches to the NO-COM path; the first high-pressure calibration gas source is closed, and the second high-pressure calibration gas source is opened. The calibration gas passes sequentially through the second pressure reducing valve, the third solenoid valve, the second solenoid valve, and the first solenoid valve to the sensor in the gas concentration analysis module, providing the second set of calibration gas flow paths; the average gas concentration is collected over a period of time to complete the zero-point calibration of the sensor; finally, all high-pressure calibration gas sources and valves are closed to complete the gas concentration calibration of the sensor.

[0010] Step 2: Conduct metabolic function tests; the test modes include two modes: spontaneous breathing resting metabolic function test and exercise metabolic function test; the exercise metabolic function test process is divided into three stages: resting stage, progressive load stage and recovery stage; in the progressive load stage, the load power starts from 0W and gradually increases in increments of 10W until the maximum oxygen uptake of the human body is reached.

[0011] Step 3: Collect and process the data to calculate human metabolic-related indicators.

[0012] The present invention has the following beneficial effects:

[0013] (1) Based on the adjustable mixing tank, physical buffering of human exhaled gas is realized, avoiding real-time analysis of human breathing gas at the millisecond level, reducing the dynamic performance requirements of the sensor, making metabolic function detection and analysis easier to implement in engineering, and by dynamically adjusting the volume of the mixing tank, the system's ability to perceive high-frequency gas concentration changes is maximized within the existing sensor accuracy tolerance range, effectively covering the rapid fluctuation of metabolic parameters during exercise.

[0014] (2) Through the exhaled air concentration detection module, constant pressure and constant flow control is realized in the process of analyzing the composition of human exhaled air and the concentration of standard air, avoiding sensor errors caused by fluctuations in air pressure and air flow, improving the accuracy of metabolic function detection, and the positive pressure suction simplifies the air path structure.

[0015] (3) This invention can meet the metabolic measurement modes of exercise and rest, and is suitable for individual metabolic measurement of different exercise intensities and respiratory rates. It has high adaptability and versatility, supports the monitoring of metabolic parameters under low-intensity to high-intensity exercise, and meets the differentiated needs of multiple fields such as sports science, clinical rehabilitation, and nutritional metabolism. Attached Figure Description

[0016] Figure 1 This is a structural diagram of a metabolic detection device based on an adjustable mixing tank according to the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above objectives, this invention adopts the following technical solution.

[0018] like Figure 1 As shown, this invention provides a metabolic detection device based on an adjustable mixing tank. The device comprises a human respiratory gas collection module, an exhaled gas concentration detection module, a calibration gas supply module, a solenoid valve switching module, a control module, and a computer. The human respiratory gas collection module separates the subject's respiratory gases, provides a respiratory pathway, detects the exhaled gas flow rate, and collects and physically averages the subject's exhaled gases. The exhaled gas concentration detection module detects the concentration of gas components in the test gas, including oxygen and carbon dioxide concentrations. The calibration gas supply module provides calibration gas for concentration calibration to the exhaled gas concentration detection module; that is, high-pressure calibration gas from a high-pressure gas source is supplied after pressure reduction and depressurization. The solenoid valve switching module provides gas switching selection for the exhaled gas concentration detection module, allowing selective supply between the subject's exhaled gases in the human respiratory gas collection module, the high-pressure gas source in the calibration gas supply module, and ambient gas. The control module controls the motors, solenoid valves, sensors, and other components in the device and acquires signals. The computer is used for data processing and analysis, index calculation, result display, and human-computer interaction.

[0019] The human respiratory gas collection module consists of a breathing mask, a first one-way valve, a second one-way valve, a third one-way valve, an adjustable mixing canister, a flow sensor, a stepper motor, a linkage mechanism, and an air tube. The inlet of the first one-way valve is connected to air, and the outlet of the first one-way valve is connected to the breathing mask and the inlet of the second one-way valve via a tee. An air tube is embedded in the central region of the piston rod of the adjustable mixing canister, extending into the interior of the canister. The adjustable mixing canister has three ports: a, b, and c. Port a is located at the end of the central air tube and is connected to the outlet of the second one-way valve via the air tube. Port b is connected sequentially to the flow sensor, the third one-way valve, and air, forming a main airflow path with a relatively large diameter and relatively low air resistance. Port c is connected to the solenoid valve switching module via a bypass sampling method, forming a concentration sampling path with a relatively small diameter. The stepper motor is sequentially connected to the linkage mechanism and the piston rod of the adjustable mixing canister.

[0020] The specific operation of the human respiratory gas collection module is as follows: During the subject's inhalation phase, air enters the breathing mask through the first one-way valve and is inhaled by the subject. During the subject's exhalation phase, the exhaled air flows sequentially through the breathing mask, the second one-way valve, the adjustable mixing canister, and the flow sensor, ultimately returning to the air, forming a complete respiratory cycle. Simultaneously, the subject's exhaled gas in the adjustable mixing canister is sampled through the gas bypass at port C of the adjustable mixing canister and sent to the solenoid valve switching module for subsequent analysis of the subject's exhaled gas concentration. During exhalation, the subject's tidal volume is first measured using the flow sensor, and combined with the upper limit of the analysis bandwidth of the oxygen and carbon dioxide sensors in the exhaled gas concentration detection module, the required volume of the adjustable mixing canister is obtained. Subsequently, the stepper motor is controlled to rotate according to a preset number of revolutions and direction, driving the piston rod of the adjustable mixing canister to move linearly through a linkage mechanism, thereby adjusting the volume of the adjustable mixing canister. When the stepper motor reaches the preset number of revolutions, it stops automatically. At this time, the volume of the adjustable mixing tank is fixed at the target value, thus completing the closed-loop control of the volume of the adjustable mixing tank and effectively reducing the requirements for the dynamic performance of the sensor.

[0021] The exhaled air concentration detection module consists of a first suction pump, a second suction pump, a first air resistance, a second air resistance, a third air resistance, a fourth air resistance, a first buffer tank, a second buffer tank, a carbon dioxide sensor, a zirconia oxygen sensor, a fourth one-way valve, a fifth one-way valve, a first differential pressure sensor, a second differential pressure sensor, and a tubing. The zirconia oxygen sensor has four ports: a, b, c, and d. The first suction pump drives two gas flow paths. The inlet of the first suction pump is connected to a solenoid valve switching module via a tubing, and its outlet is connected to two gas flow paths: one is connected to the first buffer tank and the first air resistance sequentially to air via a tubing; the other is connected to the second air resistance, the carbon dioxide sensor, port a of the zirconia oxygen sensor, port c of the zirconia oxygen sensor, and the fourth one-way valve sequentially to air via a tubing. The second suction pump drives two gas flow paths. The inlet of the second suction pump... The outlet is connected to the air via a tubing, and its outlet is connected to two gas flow paths: one is connected to the second buffer tank and the fourth air resistance via a tubing, and then to the air; the other is connected to the third air resistance, the b port of the zirconia oxygen sensor, the d port of the zirconia oxygen sensor, and the fifth one-way valve via a tubing, and then to the air. One end of the first differential pressure sensor is connected to the c port of the zirconia oxygen sensor via a tubing, and the other end is connected to the air via a tubing. One end of the second differential pressure sensor is connected to the d port of the zirconia oxygen sensor via a tubing, and the other end is connected to the air via a tubing.

[0022] During the operation of the exhaled gas concentration detection module, the first and second suction pumps are responsible for driving the flow of two sets of air paths, respectively. Both the first and second suction pumps adopt a negative pressure suction and positive pressure exhaust mechanism: when the first suction pump is working, its inlet forms a negative pressure state, drawing the gas to be tested from the solenoid valve switching module pipeline into the pump body. After compression, a pressure higher than atmospheric pressure is formed at the outlet, causing the gas to be tested to be discharged from the outlet of the first suction pump at positive pressure. When the second suction pump is working, its inlet forms a negative pressure state, drawing air into the pump body. After compression, a pressure higher than atmospheric pressure is formed at the outlet, causing the air to be discharged from the outlet of the first suction pump at positive pressure. This ensures that the gas can be stably and continuously propelled through subsequent sensors, buffer tanks, and air resistance components. Specifically, the inlet of the first air pump is connected to the gas to be tested through a solenoid valve switching module, and its outlet divides the gas into two paths: one path passes through the second gas barrier, carbon dioxide sensor, zirconia oxygen sensor port a, zirconia oxygen sensor port c, and the fourth one-way valve in sequence and returns to the air; the other path passes through the first buffer tank and the first gas barrier in sequence and returns to the air. The zirconia oxygen sensor and carbon dioxide sensor are used to detect the concentration of oxygen and carbon dioxide components in the gas to be tested. The first buffer tank and the first gas resistance are used to stabilize the airflow and reduce the flow fluctuation when the first pump is pumping air. At the same time, during the flow of the gas to be tested, based on the PID negative feedback control algorithm, the pressure difference at port c of the zirconia oxygen sensor detected by the first differential pressure sensor is used as the observation signal to adjust the pumping power of the first pump, so as to achieve that the gas to be tested flows into the zirconia oxygen sensor at a constant pressure and flow rate. The inlet of the second pump is directly connected to the air, and its outlet divides the gas into two paths: one path passes through the third gas resistance, port b of the zirconia oxygen sensor, port d of the zirconia oxygen sensor, and the fifth one-way valve in sequence and returns to the air; the other path passes through the second buffer tank and the fourth gas resistance in sequence and returns to the air. The zirconia oxygen sensor is used to detect the concentration of oxygen components in the air; the second buffer tank and the fourth air resistance are used to stabilize the airflow and reduce the flow fluctuation when the second air pump is pumping air; at the same time, during the air flow, based on the PID negative feedback control algorithm, the pressure difference at the d port of the zirconia oxygen sensor detected by the second differential pressure sensor is used as the observation signal to adjust the pumping power of the second air pump, so as to achieve that the air flows into the zirconia oxygen sensor at a constant pressure and flow rate.

[0023] The calibration gas supply module consists of a first high-pressure calibration gas source, a second high-pressure calibration gas source, a first pressure reducing valve, a second pressure reducing valve, and a gas pipe. The first high-pressure calibration gas source is connected to the inlet of the first pressure reducing valve, and the outlet of the first pressure reducing valve is connected to the solenoid valve switching module via a gas pipe tee. The second high-pressure calibration gas source is connected to the inlet of the second pressure reducing valve, and the second pressure reducing valve is connected to the solenoid valve switching module via a gas pipe tee.

[0024] The solenoid valve switching module consists of a first solenoid valve, a second solenoid valve, a third solenoid valve, and an air tube. The first, second, and third solenoid valves are all two-position three-way valves, with the COM port being a common port, the NO port a normally open port, and the NC port a normally closed port. The NC port of the third solenoid valve is connected to the first pressure reducing valve in the calibration gas supply module via an air tube tee, and its COM port is connected to the NO port of the second solenoid valve, which is connected to air. The NC port of the second solenoid valve is connected to the second pressure reducing valve in the calibration gas supply module via an air tube tee, and its COM port is connected to the NC port of the first solenoid valve. The NO port of the first solenoid valve is connected to the outlet of the adjustable mixing tank in the human respiratory gas collection module, and its COM port is connected to the inlet of the first suction pump in the exhaled gas concentration detection module.

[0025] When calibrating the sensor in the gas concentration analysis module based on the first set of calibration gas concentrations: First, the first and second solenoid valves are enabled, and the gas flow path is switched to the NC-COM path, meaning gas enters from the NC port of the second solenoid valve and exits from the COM port. Then, the second high-pressure calibration gas source is closed, and the first high-pressure calibration gas source is opened. The calibration gas passes sequentially through the first pressure reducing valve, the second solenoid valve, and the first solenoid valve to the exhaled gas concentration detection module, forming the first set of standard airflow paths. The first high-pressure calibration gas source is discharged into the air through a tee tube, achieving pressure relief regulation and supply of the first set of calibration gas during sensor concentration calibration. When calibrating the sensor in the gas concentration analysis module based on the second set of standard gas concentrations: First, the first and third solenoid valves are enabled, and the gas flow path is switched to the NC-COM path, meaning gas enters from the NC port of the second solenoid valve and exits from the COM port. The second solenoid valve is deactivated, and the gas flow path is switched to the NO-COM path, meaning gas enters from the NO port of the second solenoid valve and exits from the COM port. Then, the first high-pressure calibration gas source is shut off, and the second high-pressure calibration gas source is opened. The calibration gas passes sequentially through the second pressure reducing valve, the third solenoid valve, the second solenoid valve, and the first solenoid valve to the exhaled air concentration detection module, forming the second set of standard airflow paths. The second high-pressure calibration gas source is discharged into the air through a tee tube, achieving pressure relief and supply of the second set of calibration gas during sensor concentration calibration. When calibrating the sensor in the gas concentration analysis module based on air concentration: firstly, the first solenoid valve is enabled, and the second and third solenoid valves are disabled. Then, the first and second high-pressure calibration gas sources are shut off, and air passes sequentially through the third solenoid valve, the second solenoid valve, and the first solenoid valve to the exhaled air concentration detection module. During metabolic detection based on indirect calorimetry: firstly, the first solenoid valve is disabled. Then, the first and second high-pressure calibration gas sources are shut off, and the subject's exhaled air in the adjustable mixing canister passes sequentially through the first solenoid valve's NC port and the first solenoid valve's COM port to the exhaled air concentration detection module via the adjustable mixing canister's C port.

[0026] The present invention also provides a method for detecting human metabolic capacity based on an adjustable mixing tank, which, based on the above-mentioned detection device, includes the following steps:

[0027] Step 1: The operator performs gas concentration calibration of the sensor and flow rate / volume calibration of the flow sensor.

[0028] During the calibration of the first set of calibration gas concentrations, the first and second solenoid valves are enabled, and the gas flow path is switched to the NC-COM path. The second high-pressure calibration gas source is closed, and the first high-pressure calibration gas source is opened. The calibration gas passes sequentially through the first pressure reducing valve, the second solenoid valve, and the first solenoid valve to the sensor in the gas concentration analysis module, providing the first set of calibration gas flow paths. The gas concentration average is collected over a period of time to complete the sensor's range calibration. During the calibration of the second set of calibration gas concentrations, the first and third solenoid valves are enabled, and the gas flow path is switched to the NC-COM path; the second solenoid valve is deactivated, and the gas flow path is switched to the NO-COM path. The first high-pressure calibration gas source is closed, and the second high-pressure calibration gas source is opened. The calibration gas passes sequentially through the second pressure reducing valve, the third solenoid valve, the second solenoid valve, and the first solenoid valve to the sensor in the gas concentration analysis module, providing the second set of calibration gas flow paths. The gas concentration average is collected over a period of time to complete the sensor's zero-point calibration. Finally, all high-pressure calibration gas sources and valves are closed to complete the sensor's gas concentration calibration.

[0029] Step 2: Subjects complete user registration and login on the computer, prepare for the metabolic test, and begin the test.

[0030] During the spontaneous breathing resting metabolic function test, the subject must first correctly wear a breathing mask. The subject breathes according to the spontaneous breathing rhythm: during the subject's inhalation phase, air enters the breathing mask through the first one-way valve and is inhaled by the subject. During the subject's exhalation phase, the exhaled air flows sequentially through the breathing mask, the second one-way valve, the adjustable mixing canister, and the flow sensor, finally returning to the air. During the test, a second suction pump continuously pumps air sequentially through the third air resistance, the zirconia oxygen sensor, and the fifth one-way valve to supply the reference gas for the zirconia oxygen sensor. With each exhalation, the subject's tidal volume is first measured by the flow sensor, and combined with the upper limit of the analysis bandwidth of the oxygen and carbon dioxide sensors in the exhaled air concentration detection module, the volume of the adjustable mixing canister is determined. Subsequently, a stepper motor is controlled to rotate at a preset number of revolutions and in a preset direction, driving the piston rod of the adjustable mixing canister to perform linear motion to adjust the volume of the mixing canister. Simultaneously, the first solenoid valve malfunctions, and the subject's exhaled gas in the adjustable mixing canister is sampled via a gas bypass through port C of the adjustable mixing canister, sequentially passing through the first solenoid valve, the first suction pump, the first gas resistance, the carbon dioxide sensor, port A of the zirconia oxygen sensor, port C of the zirconia oxygen sensor, and the fourth solenoid valve to the atmosphere. The zirconia oxygen sensor and the carbon dioxide sensor detect the oxygen and carbon dioxide concentrations in the subject's exhaled gas, completing the entire detection process.

[0031] When conducting exercise-based metabolic function tests on subjects, they must first correctly wear a breathing mask and prepare for exercise on an exercise load device (such as a stationary bike). The entire test process is divided into three phases: a resting phase, a progressive load phase, and a recovery phase. In each phase, subjects must breathe spontaneously (the breathing rate is slower in the resting phase, moderate in the recovery phase, and fastest in the progressive load phase), following the same process as the spontaneous breathing resting metabolic function test. In the progressive load phase, the load power starts from 0W and increases incrementally in increments of 10W, with each adjustment followed by a one-minute pause, until oxygen uptake no longer increases (at which point the body's maximum oxygen uptake has been reached).

[0032] Step 3: Based on the data collected and uploaded by the control module, the computer calculates relevant indicators of human metabolism: oxygen uptake per minute and carbon dioxide production per minute. The formula derivation is as follows:

[0033] (1)

[0034] (2)

[0035] in, The mean oxygen concentration (%) of each breath exhaled by the subject. The mean concentration of carbon dioxide in each breath exhaled by the subject (%). The mean oxygen concentration (%) of each breath inhaled by the subject. The mean concentration of carbon dioxide in each breath inhaled by the subject (%). Oxygen uptake per minute ( ); Carbon dioxide production per minute ( In particular, and The concentrations of oxygen and carbon dioxide in the environment can be measured offline.

[0036] Based on the volume of the adjustable mixing canister, the formulas for the average component concentration and average flow rate of each exhaled breath are derived as follows:

[0037] (3)

[0038] (4)

[0039] (5)

[0040] in, The volume of the adjustable mixing tank ( ); , These are the oxygen and carbon dioxide concentrations (%) output by the exhaled breath concentration detection module, respectively. The flow rate output by the human respiratory gas collection module ( ).

[0041] According to equations (3) and (4), it is necessary to perform time alignment on the flow and concentration signals. Considering the principle of the flow sensor, it can be approximated as having no delay. The concentration signal is obtained by the exhaled gas concentration detection module sampling the gas concentration at the outlet of the adjustable mixing tank in a bypass manner, which has a large transmission delay. In order to clarify the transmission delay of the above concentration sampling process, a time alignment method is designed in the calibration gas path of the exhaled gas concentration detection module. Specifically, one is a time calibration method based on the solenoid valve: in the process of concentration sampling and calibration gas path design, the pipeline from the inlet of the concentration detection module to the concentration sensor and the pipeline from the outlet of the standard gas solenoid valve to the concentration sensor are ensured to be of equal length and diameter, or highly reused gas path. In the calibration process, the time from the opening of the calibration solenoid valve to the sensor receiving the concentration signal is calculated to clarify the transmission delay of the concentration sampling process; the other is a waveform feature recognition method: in the process of exhalation, the concentration signal will reach an extreme value at the end of exhalation, that is, the minimum oxygen concentration and the maximum carbon dioxide concentration. Based on the above characteristics, the end-expiratory time of flow and concentration can be identified during data analysis, thereby clarifying the transmission delay of the concentration sampling process.

[0042] The respiratory quotient (RQ) can be calculated from the oxygen uptake per minute and carbon dioxide production per minute mentioned above. Then, the metabolic rate (EE) can be calculated based on the Weir formula, thereby realizing a metabolic detection based on an adjustable mixing tank.

[0043] Specifically, after conducting exercise-metabolic function tests on the subjects, the anaerobic threshold (AT) was also calculated, in units of... The anaerobic threshold typically refers to the state in which the body shifts from primarily aerobic metabolism to partially anaerobic metabolism during exercise. The calculation process is shown below:

[0044] Create two separate arrays for VO2 and VCO2 for each breath in the progressively increasing stages, with each array corresponding to the previous one. For example, VO2List = [VO21, VO22, ..., VO2]. i ], VCO2List=[VCO21, VCO22,..., VCO2 i [i] represents the i-th breath. A function is established based on the VO2-VCO2 mapping relationship, and divided into two segments: RQ<1.0 and RQ≥1.0. Each segment is fitted to a straight line using the least squares method, and the function is:

[0045] (6)

[0046] Where x is VO2, y is VCO2, k is the slope, and b is the intercept. The formulas for calculating k and b are:

[0047] (7)

[0048] (8)

[0049] (9)

[0050] (10)

[0051] Assume the linear function for the segment RQ < 1.0 is... The linear function for the segment RQ≥1.0 is: Then the intersection point of the two lines for:

[0052] (11)

[0053] (12)

[0054] Where AT is the anaerobic threshold and M is the subject's weight in kg.

Claims

1. A metabolic detection device based on an adjustable mixing tank, characterized in that, The device consists of a human respiratory gas collection module, an exhaled gas concentration detection module, a calibration gas supply module, a solenoid valve switching module, a control module, and a computer. The human respiratory gas collection module is used to separate the breath gas of the subject, provide a breathing pathway, detect the exhaled gas flow rate, and collect and physically average the subject's exhaled gas. The exhaled gas concentration detection module is used to detect the concentration of gas components in the gas to be tested, including the concentration of oxygen and carbon dioxide. The calibration gas supply module provides calibration gas for concentration calibration to the exhaled breath concentration detection module. This is achieved by supplying high-pressure calibration gas from a high-pressure gas source after pressure reduction and depressurization. The solenoid valve switching module provides gas switching options for the exhaled breath concentration detection module, allowing selective supply between the subject's exhaled breath in the human respiratory gas collection module, the high-pressure gas source in the calibration gas supply module, and ambient gas. The control module handles control and signal acquisition. The computer is used for data processing and analysis, index calculation, result display, and human-computer interaction.

2. The metabolic detection device based on an adjustable mixing tank according to claim 1, characterized in that, The human respiratory gas collection module consists of a breathing mask, a first one-way valve, a second one-way valve, a third one-way valve, an adjustable mixing tank, a flow sensor, a stepper motor, a linkage mechanism, and an air tube. The inlet of the first one-way valve is connected to air, and the outlet of the first one-way valve is connected to the breathing mask and the inlet of the second one-way valve via a tee. An air tube is embedded in the central region of the piston rod of the adjustable mixing tank, extending into the interior of the mixing tank. The adjustable mixing tank has three ports: a, b, and c. Port a is located at the end of the central air tube and is connected to the outlet of the second one-way valve via an air tube. Port b is connected in sequence to the flow sensor, the third one-way valve, and air, forming a main airflow path with a relatively large diameter and relatively low air resistance. Port c is connected to the solenoid valve switching module via a bypass sampling method, forming a concentration sampling path with a relatively small diameter. The stepper motor is connected in sequence to the linkage mechanism and the piston rod of the adjustable mixing tank.

3. A metabolic detection device based on an adjustable mixing tank according to claim 2, characterized in that, The specific working principle of the human respiratory gas collection module is as follows: During the subject's inhalation phase, air enters the breathing mask through the first one-way valve and is inhaled by the subject. During the subject's exhalation phase, the exhaled air flows sequentially through the breathing mask, the second one-way valve, the adjustable mixing canister, and the flow sensor, ultimately returning to the air, forming a complete respiratory cycle. Simultaneously, the subject's exhaled gas in the adjustable mixing canister is sampled through the gas bypass at port C of the adjustable mixing canister and sent to the solenoid valve switching module for subsequent analysis of the subject's exhaled gas concentration. During the process, the tidal volume of the subject's breath is first measured using a flow sensor, and the upper limit of the analysis bandwidth of the oxygen and carbon dioxide sensors in the exhaled air concentration detection module is combined to obtain the required volume of the adjustable mixing tank. Then, the stepper motor is controlled to rotate according to the preset number of revolutions and direction, and the piston rod of the adjustable mixing tank is driven to move linearly through the linkage mechanism to adjust the volume of the adjustable mixing tank. When the stepper motor reaches the preset number of revolutions, it stops automatically. At this time, the volume of the adjustable mixing tank is fixed at the target value, thus completing the closed-loop control of the volume of the adjustable mixing tank.

4. The metabolic detection device based on an adjustable mixing tank according to claim 1, characterized in that, The exhaled air concentration detection module consists of a first suction pump, a second suction pump, a first air resistance, a second air resistance, a third air resistance, a fourth air resistance, a first buffer tank, a second buffer tank, a carbon dioxide sensor, a zirconia oxygen sensor, a fourth one-way valve, a fifth one-way valve, a first differential pressure sensor, a second differential pressure sensor, and a tubing. The zirconia oxygen sensor has four ports: a, b, c, and d. The first suction pump drives two gas flow paths. The inlet of the first suction pump is connected to a solenoid valve switching module via a tubing, and its outlet is connected to two gas flow paths: one is connected to the first buffer tank and the first air resistance via a tubing to air; the other is connected to the second air resistance, the carbon dioxide sensor, and the zirconia oxygen sensor via a tubing. The system connects to air via a gas sensor (port a), a zirconia oxygen sensor (port c), and a fourth one-way valve. A second air pump drives two gas flow paths. The inlet of the second air pump is connected to air via an air pipe, and its outlet is connected to two gas flow paths: one is connected to the second buffer tank and the fourth air resistance via an air pipe; the other is connected to the third air resistance, the zirconia oxygen sensor (port b), the zirconia oxygen sensor (port d), and the fifth one-way valve via an air pipe. One end of the first differential pressure sensor is connected to the zirconia oxygen sensor (port c) via an air pipe, and the other end is connected to air via an air pipe. One end of the second differential pressure sensor is connected to the zirconia oxygen sensor (port d) via an air pipe, and the other end is connected to air via an air pipe.

5. A metabolic detection device based on an adjustable mixing tank according to claim 4, characterized in that, During the operation of the exhaled gas concentration detection module, the first and second suction pumps are used to drive the flow of two sets of air paths, respectively. Both the first and second suction pumps adopt a negative pressure suction and positive pressure exhaust mechanism: when the first suction pump is working, its air inlet forms a negative pressure state, drawing the gas to be tested from the solenoid valve switching module pipeline into the pump body. After compression, a pressure higher than atmospheric pressure is formed at the air outlet, causing the gas to be tested to be discharged from the air outlet of the first suction pump at positive pressure; when the second suction pump is working, its air inlet forms a negative pressure state. Air is drawn into the pump body and compressed, creating a pressure higher than atmospheric pressure at the outlet, causing the air to be discharged at positive pressure from the outlet of the first suction pump. The inlet of the first suction pump is connected to the gas to be measured via a solenoid valve switching module, and its outlet divides the gas into two paths: one path passes sequentially through the second gas resistance, the carbon dioxide sensor, the a port of the zirconia oxygen sensor, the c port of the zirconia oxygen sensor, and the fourth one-way valve back to the air; the other path passes sequentially through the first buffer tank and the first gas resistance back to the air. The zirconia oxygen sensor... The device and carbon dioxide sensor are used to detect the concentration of oxygen and carbon dioxide components in the gas to be tested. Simultaneously, during the flow of the gas to be tested, the pressure difference at port c of the zirconia oxygen sensor detected by the first differential pressure sensor is used as an observation signal to adjust the pumping power of the first pump, ensuring that the gas to be tested flows into the zirconia oxygen sensor at a constant pressure and flow rate. The inlet of the second pump is directly connected to air, and its outlet divides the gas into two paths: one path passes sequentially through the third air resistance, port b of the zirconia oxygen sensor, port d of the zirconia oxygen sensor, and the fifth one-way valve back to air; the other path passes sequentially through the second buffer tank and the fourth air resistance back to air. The zirconia oxygen sensor is used to detect the concentration of oxygen components in the air. The second buffer tank and the fourth air resistance are used to stabilize the airflow and reduce flow fluctuations during the pumping of the second pump. Furthermore, during air flow, the pressure difference at port d of the zirconia oxygen sensor detected by the second differential pressure sensor is used as an observation signal to adjust the pumping power of the second pump, ensuring that air flows into the zirconia oxygen sensor at a constant pressure and flow rate.

6. A metabolic detection device based on an adjustable mixing tank according to claim 1, characterized in that, The calibration gas supply module consists of a first high-pressure calibration gas source, a second high-pressure calibration gas source, a first pressure reducing valve, a second pressure reducing valve, and a gas pipe. The first high-pressure calibration gas source is connected to the inlet of the first pressure reducing valve, and the outlet of the first pressure reducing valve is connected to the solenoid valve switching module through a gas pipe tee. The second high-pressure calibration gas source is connected to the inlet of the second pressure reducing valve, and the second pressure reducing valve is connected to the solenoid valve switching module through a gas pipe tee.

7. A metabolic detection device based on an adjustable mixing tank according to claim 6, characterized in that, The solenoid valve switching module consists of a first solenoid valve, a second solenoid valve, a third solenoid valve, and an air tube. The first, second, and third solenoid valves are all two-position three-way valves, with the COM port being a common port, the NO port being a normally open port, and the NC port being a normally closed port. The NC port of the third solenoid valve is connected to the first pressure reducing valve in the calibration gas supply module via an air tube tee, and its COM port is connected to the NO port of the second solenoid valve, which is connected to air. The NC port of the second solenoid valve is connected to the second pressure reducing valve in the calibration gas supply module via an air tube tee, and its COM port is connected to the NC port of the first solenoid valve. The NO port of the first solenoid valve is connected to the outlet of the adjustable mixing tank in the human respiratory gas collection module, and its COM port is connected to the inlet of the first suction pump in the outlet gas concentration detection module.

8. A method for detecting human metabolic capacity based on the device of any one of claims 1-7, comprising the following steps: Step 1: Perform gas concentration calibration for the sensor and flow rate / volume calibration for the flow sensor. During the calibration of the first set of calibration gas concentrations, enable the first and second solenoid valves, switching the gas flow path to the NC-COM pathway. Close the second high-pressure calibration gas source and open the first high-pressure calibration gas source. The calibration gas passes sequentially through the first pressure reducing valve, the second solenoid valve, and the first solenoid valve to the sensor in the gas concentration analysis module, providing the first set of calibration gas flow paths. After gas flow and collection of the average gas concentration over a period of time, complete the sensor's range calibration. Then, perform the calibration of the second set of calibration gas concentrations. When the first and third solenoid valves are enabled, the gas flow path switches to the NC-COM path; when the second solenoid valve is disabled, the gas flow path switches to the NO-COM path; the first high-pressure calibration gas source is closed, and the second high-pressure calibration gas source is opened. The calibration gas passes sequentially through the second pressure reducing valve, the third solenoid valve, the second solenoid valve, and the first solenoid valve to the sensor in the gas concentration analysis module, providing the second set of calibration gas flow paths; the average gas concentration is collected over a period of time to complete the zero-point calibration of the sensor; finally, all high-pressure calibration gas sources and valves are closed to complete the gas concentration calibration of the sensor. Step 2: Conduct metabolic function tests; the test modes include two modes: spontaneous breathing resting metabolic function test and exercise metabolic function test; the exercise metabolic function test process is divided into three stages: resting stage, progressive load stage and recovery stage; in the progressive load stage, the load power starts from 0W and gradually increases in increments of 10W until the maximum oxygen uptake of the human body is reached. Step 3: Collect and process the data to calculate human metabolic-related indicators.

9. The method for detecting human metabolic capacity according to claim 8, characterized in that, The relevant indicators include oxygen uptake per minute and carbon dioxide production per minute, calculated using the following formulas: (1) (2) in, The average oxygen concentration in each breath exhaled by the subject. The average carbon dioxide concentration in each breath exhaled by the subject. The average oxygen concentration of each breath inhaled by the subject. The average carbon dioxide concentration in each breath inhaled by the subject. Oxygen uptake per minute; The formulas are as follows: (1) Carbon dioxide production per minute; (2) Average component concentration of each exhaled breath; (3) Average exhaled breath flow rate; (4) The formulas are as follows: (3) (4) (5) in, The volume of the adjustable mixing tank; , These are the oxygen and carbon dioxide concentrations output by the exhaled breath concentration detection module, respectively. The flow rate output by the human respiratory gas collection module.

10. A method for detecting human metabolic capacity according to claim 8, characterized in that, Related indicators also include: anaerobic threshold (AT), the calculation process of which is shown below: Create two separate arrays for VO2 and VCO2 for each breath in the progressively increasing stages, corresponding one-to-one: VO2List = [VO21, VO22, ..., VO2...]. i ], VCO2List=[VCO21, VCO22,..., VCO2 i Let i represent the i-th breath. A function is established based on the mapping relationship between VO2 and VCO2, and divided into two segments: RQ < 1.0 and RQ ≥ 1.

0. Each segment is fitted to a straight line using the least squares method. The function is: (6) Where x is VO2, y is VCO2, k is the slope, and b is the intercept. The formulas for calculating k and b are: (7) (8) (9) (10) Assume the linear function for the segment RQ < 1.0 is... The linear function for the segment RQ≥1.0 is: Then the intersection of the two lines for: (11) (12) Where M represents the subject's weight.

11. The method for detecting human metabolic capacity according to claim 8, characterized in that, Step two is as follows: During resting or exercise-based metabolic function testing, subjects first correctly wear the breathing mask and breathe according to their spontaneous breathing rhythm: During inhalation, air enters the mask through the first one-way valve and is inhaled; during exhalation, exhaled air flows sequentially through the mask, the second one-way valve, the adjustable mixing canister, and the flow sensor, ultimately returning to the air. Throughout the test, a second suction pump continuously pumps air sequentially through the third air resistance, the zirconia oxygen sensor, and the fifth one-way valve to supply the reference gas for the zirconia oxygen sensor. With each exhalation, the subject's tidal volume is first measured using the flow sensor, and this is combined with the exhaled air concentration detection. The upper limit of the analysis bandwidth of the oxygen and carbon dioxide sensors in the module determines the volume of the adjustable mixing tank. Then, the stepper motor is controlled to rotate in a preset number of revolutions and direction, driving the piston rod of the adjustable mixing tank to perform linear motion to adjust the volume of the mixing tank. At the same time, the first solenoid valve is disabled, and the gas exhaled by the subject in the adjustable mixing tank is sampled through the gas bypass at port C of the adjustable mixing tank and passes sequentially through the first solenoid valve, the first suction pump, gas resistance 1, carbon dioxide sensor, port A of zirconia oxygen sensor, port C of zirconia oxygen sensor, and the fourth solenoid valve to the atmosphere. Among them, the zirconia oxygen sensor and the carbon dioxide sensor detect the oxygen and carbon dioxide concentrations in the subject's exhaled gas, completing the entire detection process.

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