Self-contained wearable metabolic analyzer

Abstract

A standalone, fully integrated, self-contained wearable metabolic analyzer for measuring metabolic rate and respiratory quotient comprises: a device body, a disposable mask and a headband. The device body comprises a plurality of different miniaturized modules, including a colorimetric sensing module, a flow module, a control circuit, a power module, an environmental sensor, a wireless module, a communication module, a storage module, a signal processing module and a display module. A disposable sensor chip coated with a chemical sensing probe is used in the colorimetric sensing module to detect O2 and CO2 in exhaled air. A flow module based on a venturi tube and a pressure sensor measures the exhaled flow. The self-contained wearable metabolic analyzer obtains physiological parameters including resting energy expenditure (REE), respiratory quotient (RQ), oxygen consumption (VO2), carbon dioxide production (VCO2), minute ventilation (VE), respiratory rate (BF) and tidal volume (TV).

Description

Technical Field

[0001] The present disclosure relates to a wearable, stand-alone, fully integrated metabolic analyzer for determining metabolic rate and respiratory quotient based on indirect calorimetry. Background Art

[0002] The significance of measuring metabolic rate

[0003] Resting metabolic rate accounts for 80% of the total energy consumed by the human body and plays a very important role in determining the energy balance of the human body. Resting metabolic rate is widely used in weight loss, nutrition, fitness and chronic disease management. Although the Harris-Benedict equation and the Mifflin-St.Jeor equation have been used to calculate the resting metabolic rate based on the user's weight, height, gender and age, these equations are estimated based on average population numbers rather than accurate measurements for individuals, and their error rate is greater than 50%. In order to achieve better health outcomes and more effectively control weight, a device that can accurately and reliably measure an individual's metabolic rate is needed. In addition to metabolic rate, respiratory quotient (RQ) is another parameter that helps assess the body's flexibility in oxidizing fatty acids and / or carbohydrates. This parameter changes in different chronic diseases such as diabetes, hypothyroidism and metabolic syndrome. RQ indicates the source of energy, which cannot be estimated by equations, but can be determined by measurement based on indirect calorimetry (as described below).

[0004] Indirect calorimetry is the gold standard for measuring metabolic rate

[0005] There are two recognized methods for measuring an individual's metabolic rate: direct calorimetry and indirect calorimetry. The former requires the subject to stay in a closed room under controlled conditions for 24 hours while the heat generated is monitored and the metabolic rate is determined from the heat generated. This method accurately measures metabolic rate but is no longer used due to practical reasons. The latter measures metabolic rate by analyzing the rate of oxygen consumption and carbon dioxide production in the exhaled breath. Indirect calorimetry can also determine the respiratory quotient of an individual by the ratio between carbon dioxide production and oxygen consumption. The measured parameters are used together with the Weir Equation to calculate the metabolic rate. This method is widely used for non-invasive and accurate measurement of metabolic rate and is the gold standard for measuring energy consumption in clinical settings.

[0006] Current metabolic analyzers based on indirect calorimetry

[0007] To measure metabolic rate and respiratory quotient by indirect calorimetry, sensors are used to measure the concentration of oxygen and carbon dioxide in the exhaled breath and the exhaled flow rate. Some widely used examples of metabolic analyzers include metabolic carts, such as the Ultima CCM from MGC Diagnostics. TM Indirect calorimeter, CareFusio's Oxycon cardiopulmonary function monitor, and Parvo Medics' Parvo 2400 metabolic measurement system. Although these devices are generally accurate and reliable, they are bulky, expensive, and require special personnel to operate, calibrate, and maintain. Therefore, these devices are only suitable for hospitals and research institutions. In order to meet the needs of small clinics, fitness or weight loss clubs, and end users, several portable metabolic analyzers have been launched on the market, including desktop devices such as Cosmed's Fitmate pulmonary function / metabolism meter and KORR's REEVUE indirect calorimeter, as well as handheld devices such as Microlife's Medgm indirect calorimeter, Metaflow's Lumen breath analyzer, and TF Health's Breezing ( TM )Basal metabolic rate meter.

[0008] Other portable indirect calorimeters have been developed to assess energy expenditure and lactate threshold during exercise by using a mask connected to a device that measures oxygen consumption rate and carbon dioxide production rate. These devices are attached to the body via a strap that secures the device, which is connected to the mask inlet and outlet to extract a portion of the inhaled or exhaled air. Examples of such systems include Cosmed's K4b and K5 wearables, CareFusion's Oxycon Mobile portable exercise cardiopulmonary function meter, and Vacumed's Turbo Trainer system.

[0009] The need for a self-contained wearable metabolic analyzer

[0010] The metabolic carts and portable metabolic analyzers described above address certain needs for measuring metabolic rate, but are expensive, complex, and difficult to use in a user's home or in a low-resource setting. There is a need for a simple, convenient, user-friendly, and cost-effective metabolic rate measurement device. The present disclosure addresses this need by providing a breakthrough new product design that utilizes innovative wearable technology to measure metabolic rate and respiratory quotient.

[0011] Using the mask as a platform to measure physiological parameters

[0012] Traditionally, masks are used for athlete training, patient care, and environmental protection. Recently, attempts have been made to introduce different sensors into masks to monitor physiological parameters. For example, a mask with built-in sensors for monitoring vital functions is described in U.S. Patent No. 4,875,477. These sensors include a temperature sensor and a heart rate monitor installed inside the mask to detect the wearer's vital functions. The mask described in U.S. Patent No. US7204250B1 granted to Burton on April 17, 2007 includes other sensors, such as a blood oxygen sensor, a position sensor, a leak sensor, an electrocardiogram (ECG) sensor, and a temperature sensor for the treatment of sleep and breathing disorders and anesthesia monitoring. The mask is connected to an external gas delivery system to adjust the gas delivery settings based on data from the sensor. In another example, U.S. Patent No. 7,575,005B2 describes a mask assembly with an integrated sensor for treating obstructive sleep apnea using continuous positive pressure (CPAP) from an external gas source.

[0013] Other examples include U.S. Patent No. US6899683B2 issued on May 31, 2005 to Mault et al., which discloses a breath analyzer adapted to be attached to a person's face using a mask or through a mouthpiece and nose clip invented by James Mault et al. All of the masks described above have a common limitation in that they must be connected to an external device in order to operate. Therefore, these devices are not self-contained stand-alone devices and cannot operate as self-contained wearable analyzers on the face.

[0014] In most of the public teachings, portable indirect calorimeters for assessing energy expenditure during exercise (such as those from Cosmed, Vacumed, and CareFusion) are missing another important element, namely, a practical design that addresses the issue of hygiene. The calorimeter's mask and connector (usually the turbine sensor) must be sterilized with a cleaning solution after use through a special procedure before the next user can use it. This makes the use of the calorimeter impractical and impairs its usability.

[0015] Although some public teachings have taken some of the hygiene issues into account (e.g., U.S. Patent No. 6,899,683 B2), these devices rely on the use of a disposable mask liner with a sanitary septum, which is attached to the detection unit and through which both inhaled and exhaled air pass. Nevertheless, for example in the 6,899,683 B2 patent, the disposable filter is clearly intended to be provided for one-time use. In addition, the disclosed filter cannot ensure the prevention of viral transmission. Viruses are generally between about 0.004 and 0.1 microns in size and can be transmitted by breathing through the liner, such as the 3M Company manufactured . The pad can only capture particles as small as 0.3 microns.

[0016] Recently, in order to achieve wearability, a brand name VO2 MASTER has been introduced. TM A wearable stand-alone mask device that measures the maximum rate of oxygen consumption (VO2 max). VO2 max, also known as maximum oxygen uptake, refers to the maximum amount of oxygen a person can take in during intense exercise. VO2 MASTER TM The device is intended for training physiological functions, not for measuring resting metabolic rate. This device is not designed for nutrition, weight loss or health. In terms of technology, VO2 MASTER TM The mask integrates existing electrochemical oxygen sensors and flow sensors, which are inherently non-scalable and cannot detect more chemical analytes in exhaled breath. Chemical sensors are typically large and bulky, making it difficult to stack multiple chemical sensors in the same wearable system to measure RQ, REE, and other respiratory biomarkers. In addition, VO2 MASTER TM The mask is designed for use by a single user and has no disposable parts to avoid cross-infection. This makes it unsuitable for use in a health club or clinic setting, where the device can often be used by different users or patients.

[0017] Balancing hygiene with wearability and usability has long been a challenge. In addition, for a miniature indirect calorimeter to be fully wearable and simultaneously assess metabolic rate and respiratory quotient, it is necessary to simultaneously analyze the oxygen and carbon dioxide in the exhaled breath, as well as its temperature, humidity, and volume flow rate, in order to accurately measure metabolic rate and respiratory quotient. Summary of the invention

[0018] This summary is intended to introduce selected concepts in a simplified form, which are further described in the detailed description below. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0019] The present invention discloses a self-contained wearable metabolic analysis device, comprising: a device body, which includes an integrated colorimetric sensor chip for simultaneously measuring oxygen and carbon dioxide and an integrated flow sensor module for measuring flow. A disposable mask is attached to the device body and is suitable for allowing a user to inhale air from ambient air through sterile breathing and exhale into the flow sensor module, and to take a small portion of the exhaled air and introduce it into the integrated chemical sensor module. A headband is suitable for attaching the device body to the user's head. A data transmission device is suitable for communicating with an external electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Although the novel features of certain embodiments of the present invention are particularly set forth in the appended claims, the organization and content of the present invention, as well as other objects and features of the present invention, will be better understood and appreciated from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0021] Figure 1 is a block diagram of a self-contained wearable metabolic analyzer;

[0022] Figure 2 is a diagram of an example of a self-contained wearable metabolic analyzer;

[0023] Figure 3A is a side view of an example colorimetric sensing module. Figure 3B is a top view of an example colorimetric sensing module. Figure 3C is a simulated flow distribution diagram of the colorimetric sensing module example;

[0024] Figure 4A This is a front view of a disposable mask. Figure 4B It is a top view of a disposable face mask;

[0025] Figure 5 is a structural diagram of an example of a headband of a self-contained wearable metabolic analyzer;

[0026] Figure 6 is a front view of an assembled device body of a self-contained wearable metabolic analyzer;

[0027] Figure 7 is a top view of an example of an assembled device body with a disposable mask and headband;

[0028] Fig. 8A is a schematic diagram of an example of a sensor chip, Figure 8B is a schematic diagram of an example of a QR code;

[0029] Fig. 9 is a diagram of an example of a self-contained wearable metabolic analyzer;

[0030] Fig.10 is a diagram illustrating an example of measuring resting energy expenditure (REE) and RQ using a self-contained wearable metabolic analyzer;

[0031] Fig.11 is a diagram showing an example of temperature readings from a thermistor used by a self-contained wearable metabolic analyzer to monitor ambient temperature;

[0032] Fig.12 is a diagram showing an example of temperature readings from a thermistor used in a self-contained wearable metabolic analyzer to monitor exhaled breath temperature;

[0033] Fig.13is a diagram showing an example of humidity readings of a humidity sensor used by a self-contained wearable metabolic analyzer to monitor ambient humidity;

[0034] Fig.14 is a diagram showing an example of air pressure readings of a barometer used by a self-contained wearable metabolic analyzer to monitor ambient air pressure;

[0035] Fig.15 is a diagram showing an example of correlation between expiratory flow measured by a self-contained wearable metabolic analyzer and a reference method using different expiratory curves;

[0036] Fig.16 is a diagram showing an example of correlation between inspired oxygen and carbon dioxide concentrations measured by a colorimetric chemical sensor included in a self-contained wearable metabolic analyzer and a reference method;

[0037] Fig.17 is a graph showing the correlation between the oxygen consumption rate (VO2) and carbon dioxide production rate (VCO2) measured by the self-contained wearable metabolic analyzer and the reference method;

[0038] Fig.18 is a graph showing an example of the correlation between REE and RQ measured by a self-contained wearable metabolic analyzer and a reference method; and

[0039] Fig.19 is a graph of example acetone readings from a self-contained wearable metabolic analyzer that includes chemical sensors in addition to oxygen and carbon dioxide sensors. DETAILED DESCRIPTION

[0040] Overview of Self-Contained Wearable Metabolic Analyzer

[0041] The foregoing description and drawings are of exemplary embodiments of the present invention, and any changes and modifications may be made without departing from the concept, spirit and scope of the present invention as defined in the following appended claims.

[0042] Prior patents and applications by some of the inventors of the present invention, US2013 / 0150746A1 (granted) issued on June 13, 2013, and U.S. Patent No. 10,078,074 issued on September 18, 2018 by Tsow et al. solve the above problems by disclosing a portable metabolic analyzer system and a single integrated colorimetric sensor chip, each of which consists of carbon dioxide and oxygen sensing elements. US2013 / 0150746A1 (granted) and U.S. Patent No. 10,078,074 are incorporated herein by reference. The present disclosure provides several important changes in both technology and user interface.

[0043] In terms of chemical sensing technology, an integrated and modular chemical sensing unit is introduced in the new design of the present disclosure, enabling the detection of oxygen and carbon dioxide from partial exhalation rather than full exhalation exposure. This improvement makes the colorimetric sensing module easy to configure and extends the service life of the sensor from 2 minutes to more than 10 minutes. The new design uses a venturi-based flow sensing technology to significantly reduce back pressure without sacrificing accuracy. More environmental sensors (such as barometers, humidity sensors, and gyroscopes) are used to compensate for environmental factors that may affect the measurement itself and to accommodate user comfort, which is necessary to ensure true measurement of resting metabolic rate. In terms of user interface, unlike handheld devices that only allow exhalation to be collected from the mouth, the face-mounted design promotes collection from natural breathing from the user's mouth and nose, which is critical for accurate measurement of REE.

[0044] Now refer to Figure 1 , an example of a self-contained, wearable, integrated and independent metabolic analyzer is shown in the block diagram. The multiple components in this embodiment of the self-contained wearable metabolic analyzer 1 include a device body 100, a disposable mask 101, a headband 102 and a phone / tablet / computer 103. Preferably, the device body 100 is an integrated unit composed of mechanical parts, electronic circuits and sensors, which provides the functions of exhaled flow measurement and oxygen and carbon dioxide concentration detection in exhaled air. The disposable mask 101 is an exhaled air collection unit made of mechanical parts, which covers the user's mouth and nose through an airtight seal and guides all exhaled air into the device body 100 to perform chemical analysis on the exhaled air and measure temperature, humidity and flow. The headband 102 is a set of fabric straps with hook and loop fasteners that can keep the assembled device body 100 and disposable mask 101 around the user's head during the measurement process. The phone / tablet / computer 103 is equipped with an application 121, which is connected to the device body 100 for data communication and data management, wherein the application 121 consists of the following modules:

[0045] 1) Account module 122: allows users to create, manage and delete accounts and edit user profiles;

[0046] 2) Measurement module 123: its functions include: transmitting data between the device body and the mobile phone / tablet / computer, guiding the user to perform measurements, and indicating measurement progress and attachments, such as QR code scanning;

[0047] 3) Report module 124: displays the final test results, including REE, RQ, VO2, VCO2, VE, BF and TV, and generates a test report;

[0048] 4) History module 125: stores, manages and displays the history of test results;

[0049] 5) Printing module 126: wirelessly communicates with an external printer to print a test report;

[0050] 6) Data sharing module 127: allows sharing of test results with other persons such as doctors, professionals, family members and friends via email, text messages, social media or other health platforms.

[0051] In some embodiments, the device body 100 and the disposable mask 101 are integrated or combined into one unit. This combination does not substantially affect the metabolic rate measurement and exhalation analysis functions of the self-contained wearable metabolic analyzer. However, a disinfection and cleaning procedure should be performed to clean the mask and flow channel to avoid any hygiene issues. In order to ensure a tight seal between the mask and the user's face and avoid air leakage during metabolic rate measurement, the following design features can be adopted: 1) Apply ergonomic design to the device body and its mask to conform to the contour features of the user's face; 2) Use flexible materials such as silicone rubber along the edge of the mask to provide an airtight seal when the mask is worn; 3) Provide masks of different sizes for users to choose; 4) Ensure that the openings of the inhalation and exhalation channels are large enough to reduce breathing resistance.

[0052] The device body 100 is a measurement unit fully integrated with mechanical parts, electronic circuits and sensors for detecting the exhaled air flow and its oxygen and carbon dioxide. In one example, multiple modules and components are integrated together, including a flow module 104, a colorimetric sensor module 105, a microcontroller 106, a power module 107, a display module 108, a thermistor 109, a humidity sensor 110, a barometer 111, multiple LED indicators 112, a buzzer 113, a gyroscope 114, a switch 115, a reset plug-in 116, an external port 117, a memory 118, a clock chip 119 and a transmission device 120, for example, module.

[0053] The flow module 104 monitors the flow curve of the user during the measurement. The real-time expiratory flow is monitored by the flow module 104, and after data processing, the respiratory rate, tidal volume and minute ventilation (VE) are determined based on the real-time expiratory flow. VE is a key parameter for measuring resting energy expenditure (REE). In the traditional Douglas bag method, the user needs to exhale gas into the bag to determine VE. When the bag is full, the user's exhaled volume and the time it takes to fill the bag are measured, and the VE is calculated based on the exhaled volume and time, and the VE is converted into a value under STP (standard temperature and pressure) conditions. The Douglas bag method is bulky, slow and difficult to operate. Most commercial instruments for metabolic rate measurement use flow sensors to monitor real-time flow and find the integral of time over expiratory flow to calculate the total volume and determine VE.

[0054] Rapid, continuous, and accurate monitoring of exhaled air flow is required to accurately and reliably measure VE. There are at least three recognized methods for measuring exhaled air flow. The first method uses a turbine flow meter. In a turbine flow meter, gas (e.g., exhaled air) flows through a turbine rotor and rotates the rotor, where the rotation speed is proportional to the gas flow rate. The rotor speed is monitored by optical, electrical, or electromagnetic readings to determine the gas flow rate. This method can cover a large flow range with relatively small back pressure at high exhaled air flows, but the accuracy and response time are impaired due to the inertia of the rotor. Turbine flow meters can also become contaminated after long-term exposure to exhaled air, causing accuracy and hygiene issues.

[0055] Another method of measuring exhaled air flow uses an ultrasonic flow meter. Ultrasonic flow meters use the Doppler effect to measure gas flow by detecting the frequency shift of ultrasonic waves propagating in the flowing gas. Ultrasonic flow meters are reliable and require little maintenance, but they are expensive and susceptible to temperature changes.

[0056] Another approach uses the differential pressure pneumotach approach. In this approach, a pressure differential is created by passing gas through a fixed orifice or screen. This pressure differential is associated with the volumetric flow rate of the gas. By measuring the pressure differential using a pressure sensor, the exhaled flow rate can be determined. This method of measuring exhaled flow is simple, fast in response, and cost-effective. In addition, since no gas passes through the pressure sensor during the measurement, there is little concern about exhaled condensation and contamination, which would otherwise affect the stability and accuracy of the sensor. This approach has been widely used for respiratory applications such as spirometers, metabolic carts, and other clinical uses. Since the size of MEMS-based pressure sensors is very small, if the orifice is carefully designed, the entire flow measurement module can be miniaturized to measure the exhaled flow rate. Therefore, the pneumotach approach is the preferred method for exhaled analysis. However, the key is to find an optimal method for implementing the flow measurement module so that it is suitable for the self-contained wearable metabolic analyzer disclosed in the present invention.

[0057] Now refer to Figure 2 , a micro venturi tube 200 is combined with a capacitive pressure sensor 201 to measure the exhaled air flow. Venturi tubes are widely used in fluid flow measurement, for example, water meters, gasoline meters and gas flow meters. A pressure difference is established by forming a narrow constriction section 205 with a variable cross-sectional area along the flow path (channel) to improve the accuracy of flow measurement. The relationship between the pressure difference and the flow rate is given by the Bernoulli equation:

[0058] ΔP=1 / 2(ρV 2 ) (1)

[0059] Wherein, ΔP is the pressure difference, ρ is the exhaled air density, and V is the flow rate at the orifice. The volume flow rate can be determined by the flow rate at the orifice and the cross-sectional area of ​​the narrow constriction section 205.

[0060] In addition, by designing a tapered structure after the narrow contraction section 205, the back pressure at a given flow rate can be significantly reduced. Minimizing back pressure is very important to help users maintain the natural and relaxed breathing conditions required for metabolic rate measurement. In other words, a large back pressure will change the user's resting state, resulting in inaccurate metabolic rate measurement. However, while minimizing back pressure by increasing the diameter of the narrow contraction section 205 of the venturi tube 200, the detection upper limit of the pressure sensor must be considered. If the diameter is too large, the pressure difference generated by the airflow is too small, and the pressure sensor cannot perform accurate measurements. According to the system numerical simulation and experiments conducted by the inventors herein, for most users, the measurement diameter of the resting metabolic rate is preferably in the range of about 3-25mm. In order to adapt to different uses, for example, measuring the metabolic rate of an individual during physical exercise or testing the resting metabolic rate of infants and children, a venturi tube with a narrow telescopic section 205 of different diameters can be used as a replaceable component. For example, by designing venturi tubes of various sizes, such as small, medium and large venturi tubes, a wider flow range can be covered. In other embodiments, the venturi tube 200 may also be replaced by other alternative mechanical designs to create a pressure differential along the airflow, such as a screen and an orifice.

[0061] One opening of the pressure sensor 201 is connected to the upstream of the flow path 203 in the venturi tube 200, and the other opening of the pressure sensor 201 is connected to the downstream of the flow path 204 in the venturi tube 200. The disposable mask 101 is connected to the upstream 203 so that the flow rate of the exhaled air can be measured as the gas flows through the venturi tube 200. After passing through the venturi tube, the exhaled air is directly discharged into the ambient air. There is another opening 202 upstream of the venturi tube 200. The opening 202 is designed to introduce a small portion of the total exhaled air into the colorimetric sensing module 105 for analyzing the oxygen and carbon dioxide concentrations in the user's exhaled air.

[0062] In order to convert the measured exhaled air flow into STP flow for calculation of VE and REE, a thermistor 109 is installed in a small hole at the narrow constriction section of the venturi tube 200 to monitor the exhaled air temperature. The thermistor 109 is also used to monitor the ambient temperature before starting metabolic measurement.

[0063] The colorimetric sensor module 105 monitors the oxygen and carbon dioxide concentrations in the exhaled air. The oxygen and carbon dioxide concentrations are used together with VE to calculate VO2 and VCO2 according to the following formula:

[0064] VO2=VE×(0.2093-FO2) (2)

[0065] VCO2=VE×(FCO2-0.0003) (3)

[0066] Where 0.2093 is the fraction of inspired oxygen, FO2 is the fraction of exhaled oxygen, FCO2 is the fraction of exhaled carbon dioxide, and 0.0003 is the fraction of inspired carbon dioxide.

[0067] Based on VO2 and VCO2, REE can be determined using the weir flow equation:

[0068] REE (kcal / day) = 1.44 × [3.9 × VO2 + 1.1 × VCO2] (4)

[0069] Where REE represents the energy expenditure in a resting state for 24 hours, and the unit is kilocalories per day; the oxygen consumption rate VO2 and the carbon dioxide production rate VCO2 are in milliliters per minute.

[0070] The respiratory quotient (RQ) is defined as the ratio of VCO2 to VO2 and is given by:

[0071] RQ=VCO2 / VO2 (5)

[0072] RQ is an indicator of the source of energy consumption (fat or carbohydrates), and its physiological range is between 0.67-1.3. Depending on the energy source, the RQ value is:

[0073] Fat: 0.70

[0074] Carbohydrate: 1.00

[0075] For long-term ketosis users, the RQ is equal to or less than 0.70. On the other hand, for obese users, the RQ is greater than 1.00.

[0076] Oxygen and Carbon Dioxide Sensors and Detection:

[0077] Oxygen and carbon dioxide sensors are as important as flow sensors for accurate determination of REE and RQ. At least three types of oxygen sensors are widely used for breath oxygen detection: electrochemical, paramagnetic, and fluorescence quenching oxygen sensors. The most common are electrochemical oxygen sensors based on fuel cells, which measure oxygen concentration by monitoring the oxidation current of a lead electrode. Electrochemical oxygen sensors are a mature technology and are widely used in metabolic carts. Although popular, electrochemical oxygen sensors are susceptible to temperature changes and have a limited service life (usually 6 months to 1 year). Paramagnetic oxygen sensors are sensors based on the principle of oxygen paramagnetism. They have high accuracy, long service life, and fast response, but are susceptible to humidity changes. Paramagnetic oxygen sensors are also prone to mechanical vibrations, and their large size and high price make them unsuitable for portable or self-contained wearable metabolic analyzers. Fluorescence quenching oxygen sensors are based on the principle that oxygen can quench the fluorescence emitted by metal organic dyes. Although fluorescence quenching oxygen sensors are sensitive and fast, the quenching effect of oxygen is highly sensitive to temperature. In addition, for use in self-contained wearable metabolic analyzers, fluorescence quenching oxygen sensors have the additional disadvantages of high cost and limited service life.

[0078] For the detection of exhaled CO2, the most widely used sensing technology is the non-dispersive infrared (NDIR) CO2 sensor. This sensor detects CO2 concentration by measuring the absorbance of infrared light at a specific wavelength. Since CO2 absorption is strong at 4.26 pm, this wavelength is usually used to detect CO2 concentration. One problem with using NDIR CO2 sensors is that water vapor can cause spectral interference. Therefore, the humidity in the exhaled breath must be adjusted or removed in order to achieve accurate and repeatable exhaled CO2 detection using this CO2 sensor.

[0079] Oxygen and carbon dioxide sensors are based on different signal transduction principles and are therefore two separate units, making it difficult to integrate them into a single unit of a wearable device. More specifically, the use of oxygen and carbon dioxide sensors as described in the disclosed teachings faces the following challenges: 1) the size of the oxygen and carbon dioxide sensors is large; 2) the weight of oxygen and carbon dioxide is heavy; 3) the output signals are completely different, increasing the burden on signal conditioning, amplification circuits and processing software; and 4) the flow design required to evenly deliver the breath sample to the two separate sensors is complex.

[0080] As mentioned above, the prior patents and applications, the published patent US2013 / 0150746A1 (already granted) and the U.S. Patent No. 10,078,074 of some inventors of the present invention solve the above-mentioned problems by disclosing a monolithic integrated colorimetric sensor chip, wherein each chip is composed of carbon dioxide and oxygen sensor elements. Compared with traditional chemical sensors, the sensor chip can detect multiple analytes (e.g., carbon dioxide and oxygen) through an array of sensing probes, each of which is directed to a chemical analyte. Since both sensing elements are based on colorimetry, the signal reading is simple, requiring only one light source (LED) and one photodetector array. Despite the success, the sensor chip is directly exposed to sufficient exhaled air and is integrated along the exhaled path flow with a thermistor, a flowmeter and a photodetector unit (including an LED and a photodetector array). This design is susceptible to water condensation, temperature changes and turbulence of the exhaled airflow. All of these will compromise the accuracy of CO2 and O2 analysis, which must be corrected using sophisticated hardware, such as special mechanisms for attaching the sensor to the sensing chamber to buffer the turbulence of the exhaled airflow, and mechanical fans to blow away condensed water after each measurement. This additional hardware leads to complex design, bulky size, environmental noise (when the fan is running), and energy consumption. On the other hand, the modular approach disclosed in the present invention makes its design extremely easy to assemble and calibrate, and it is extremely easy to find problems and repair or replace components.

[0081] After thousands of tests using devices based on the prior art, the inventors developed and tested new designs with innovative solutions to the above problems. In one example, the present disclosure features a colorimetric sensing module 105 ( Figures 3A-3C ), the colorimetric sensing module 105 is part of a self-contained wearable metabolic analyzer, but is used as a sensing unit for simultaneously analyzing carbon dioxide and oxygen in exhaled breath. Additional sensing elements may be included on the sensor chip to detect other chemical analytes. The detection module uses common consumer electronic components such as LEDs and photodiodes, while the sensor chip is made of common chemicals and plastics that can be made by printing and plastic molding. The sensor module consists of a miniature detector chamber into which the sensor chip is inserted. The detector chamber has an inlet and an outlet for directing a small portion of the exhaled air from the venturi tube assembly 200 through an opening 202 upstream of 200 without the use of a mechanical pump or fan.

[0082] Now refer to Figure 3A and Figure 3B, schematic diagram examples of the side view and top view of the colorimetric sensing module 105 are shown. The colorimetric sensing module has multiple components, including an LED array 304 and a circuit 305, a top support 306, a photodiode 310 and a circuit 309, a bottom support 308, a chamber cover 301, and a sensor chip 307. The LED array 304 provides uniform illumination for the sensor chip 307. In one embodiment, there is one LED for each of the four sensing areas, including a carbon dioxide sensing area 311, an oxygen sensing area 312, a carbon dioxide reference area 313, and an oxygen reference area 314, for a total of four LEDs. Since the color change caused by the reaction of oxygen and carbon dioxide in the sensing area is more sensitive to red light, in this embodiment, an LED with an illumination wavelength of 630 nm is used, and therefore the measurement of both gases is performed at a single absorption wavelength. The LED circuit 305 is assembled on the top support 306 ( Figure 3A ). Inlet 303 is an exhaled air (gas) channel with a diameter of about 1 mm, starting from one side of the top support 306 and ending near the center of the top support 306, and rotating downward 90° to guide the exhaled air to flow evenly through all four sensing areas of the sensor chip 307. There are four outlets 302 at the four corners of the top member 306 to allow the exhaled air to escape without causing a large amount of water condensation.

[0083] The colorimetric sensor module 105 is designed such that: 1) a gap of 1-3 mm is formed between the bottom surface of the top support 306 and the top surface of the sensor chip 307; and 2) one exhalation inlet is located at the center of the top support 306, and four outlets are symmetrically located at the four corners. Figure 3C As shown in the simulated flow distribution in FIG, the geometric shape enables sufficient mixing of the breath sample in the colorimetric sensing module 105 and symmetrical flow distribution, and enables effective reaction of the chemical analyte with the sensing probe in each sensing area of ​​the sensor chip 307. In addition, the module design avoids turbulence, which can accelerate sensor reaction and prevent the sensor from having a longer service life (e.g., 10 minutes).

[0084] The photodetector assembly includes a photodiode circuit 309 and a photodiode array 310. In this embodiment, at least four photodiodes are used, one for each sensing region. The four LEDs 304, sensing regions, and photodiodes 310 are aligned in the colorimetric sensing module 105. The photodiode circuit 309 is mounted on a base member 308, which has a sensor chip "lock" and "pop-up" mechanism implemented using an L-shaped bracket 315 and a spring 316, as shown in FIG. Figure 3B shown.

[0085] The sensor chip 307 is a molded plastic substrate made of an inert polymer and coated with oxygen and carbon dioxide sensing probes. There are four sensing areas on the sensor chip 307: a carbon dioxide sensing area 311, an oxygen sensing area 312, a carbon dioxide reference area 313, and an oxygen reference area 314. The carbon dioxide sensing area 311 and the oxygen sensing area 312 are uniformly coated with a certain amount of carbon dioxide and oxygen sensing probes, which react specifically with carbon dioxide and oxygen in the exhaled breath, respectively. The carbon dioxide reference area 313 and the oxygen reference area 314 are used to correct the optical signal drift caused by light intensity changes and non-chemical reactions during measurement. The chamber cover 301 is a cover made of rubber plastic. Once the sensor chip 307 is inserted into the colorimetric sensing module 105, the chamber cover 301 is used to airtightly seal the colorimetric sensing module 105. The chamber cover 301 should be opaque to block ambient light and avoid any optical interference from the colorimetric detection.

[0086] Mixing chamber technology is a widely used metabolic rate measurement method, where exhaled air enters the mixing chamber through a non-rebreathing (one-way) valve for uniform mixing to avoid short-term fluctuations in analyte concentrations. However, the volume of the mixing chamber is usually large (4-6L) and is not suitable for wearable devices. The present disclosure introduces inhalation and exhalation one-way valves directly on the disposable mask 101 to ensure that exhaled air is not re-breathed. It also uses only a small portion (less than 1%) of the total exhaled air delivered to the colorimetric sensing module 105, where the exhaled air sample is mixed and reacted with the sensing probe for carbon dioxide and oxygen analysis. This is feasible because the structure disclosed in the present invention ensures that the exhaled air volume delivered to the colorimetric sensing module 105 is proportional to the exhaled air volume exhaled through the venturi. In order to achieve effective mixing of gases in the colorimetric sensing module 105, simulations have been implemented to evaluate the flow distribution, pressure, turbulence, fluid dynamics and material transport of chemical reactions under different geometries and sizes.

[0087] Now refer to Figure 6 , the figure shows a diagram of an optimized design example, whose performance has been verified by simulation results and Fig.16 The measurement accuracy of oxygen and carbon dioxide concentrations shown in are both verified. A calibration mechanism is invented to directly correlate the flow measured by the flow module 104 and the flow detected in the colorimetric sensor module 105. The calibration mechanism takes advantage of the law that the color development of the sensing area depends on the analyte concentration and material transport.

[0088] Metabolic Analyzer Design, Parts, Components and Wearability:

[0089] Now refer to Figure 4A and Figure 4B, a schematic diagram of an example of a front view and a side view of a disposable mask 101 is shown. The disposable mask has at least five main components, including a mask body 401 with a cushion layer 402 along the edge, an exhalation check valve 403, an inhalation check valve 404, and a connecting adapter 405. The mask body 401 is a molded part with a concave shape that fits the contour of the human face. The cushion layer 402 is made of a soft material to provide a comfortable and airtight seal to the face during measurement. The exhalation valve 403 is a non-rebreathing (one-way) valve located in the middle of the mask body 401, which allows exhaled air to flow freely from the disposable mask 101 to the venturi tube 202. In order to minimize the resistance to exhalation flow, the diameter of the exhalation check valve 403 should be in the range of 20-40 mm. For inhalation, an inhalation check valve 404 is used to allow the user to inhale fresh ambient air into the mask. Multiple inhalation check valves 404 can be provided to minimize the resistance to inhalation flow. The connection adapter 405 is a part of the disposable mask 101, and is used to provide an airtight connection to the venturi tube 202 when the disposable mask 101 is assembled with the device body 100. For users with different face shapes and face sizes, disposable masks of different sizes are preferred, such as small, medium, and large masks. The disposable mask 101 can be removed from the device body 100 for disinfection. The no rebreathing feature of the disposable mask 101 avoids cross contamination between different users.

[0090] Now refer to Figure 5 , a schematic diagram of an example of a headband 102 for fastening a disposable mask 101 to a device body 100 is shown. The headband includes a fabric band 503 for wrapping the user's head. In order to position the device body in a balanced and stable manner, in one embodiment, a double fabric band is used, and four contact points are formed with the device body. In one embodiment, a hook (501) and loop (502) fastener is used to provide a simple, easy and adjustable wearing method for the user.

[0091] Now refer to Figure 6 , a schematic diagram of an example of a front view of an embodiment of a device body 100 is shown. The device body 100 is arc-shaped, matching the shape of a human face. The device body 100 includes a left, middle and right part. Mechanical and electrical components are distributed in different parts according to their functions and the weight balance in the device. For example, all components are fixed to the rear panel 602 of the device by fastening elements (such as screws, etc.).

[0092] The left part is assembled with a printed circuit board assembly (PCBA) 601. The microcontroller unit (MCU) 106 controls other electronic components and processes signals from different sensors. In one example, the transmission module 120, for example, (BT) module or equivalent, responsible for data communication between the device body 100 and the tablet / phone / computer 103. The pressure sensor 201 is located on the PCBA601, and the two openings are connected to the upstream 203 and downstream 204 of the venturi tube 200 respectively. The switch 115 is located at the bottom of the PCBA601, and its button protrudes for easy operation. The electrical connector 603 is connected to other separate electronic components, including the power module 107, the display module 108 and the thermistor 109 through the cable 604. The exhaled air temperature read from the thermistor 109 is used to convert the exhaled air volume flow rate into a volume flow rate under standard temperature and pressure (STP) conditions. In this embodiment, the signal port 604 is a micro USB interface, which can be used for both data communication and battery charging. Other electronic components on the PCBA601 (for more details, see Figure 1 )include:

[0093] 1) Humidity sensor 110, used to monitor the ambient humidity. If the ambient humidity is higher than the allowed operating humidity, in one example, a warning message is displayed to remind the user to comply with the operating conditions.

[0094] 2) A barometer 111 monitors ambient air pressure. If the ambient air pressure exceeds the allowable operating pressure range, the data from the barometer is used to alert the user. The air pressure reading is also used to convert the exhaled volume flow rate to a volume flow rate at standard temperature and pressure (STP) conditions.

[0095] 3) Buzzer 113, to provide audio feedback to the user when certain actions are performed during the measurement, such as turning the device on / off, or when the measurement is completed.

[0096] 4) A gyroscope, mounted to detect the orientation of the device body during measurement. This information is used to correct for orientation-induced baseline changes in the pressure sensor. The gyroscope may be replaced by an accelerometer or other sensor to determine the orientation of the device.

[0097] 5) Resetter 116, allowing the user to reset the device to a default state when fail-safe functionality is desired.

[0098] 6) Memory 118, used to store firmware code and test data.

[0099] 7) Clock chip 119, used to create measurement time stamps. In order to enable the clock chip to operate continuously for a long time (e.g., 5-10 years), a coin-type battery with high power capacity is specially provided to drive the clock chip even when the device body is turned off.

[0100] 8) LED indicators 112, which provide visual feedback to the user regarding the status of the device, such as battery level, charging status, and measurement status.

[0101] The display module 108, the venturi tube 200 and thermistor 109 are assembled in the middle. In this embodiment, the display module 108 is an organic electro-optical laser display (OLED), which can display text, numbers and graphics. In other embodiments, other displays such as a liquid crystal display (LCD), a segment display and a touch screen display can be used. The display can show different information to the user during the measurement, including but not limited to 1) the status of the self-contained wearable metabolic analyzer (ready, measuring and completed); 2) battery power; 3) charging status; 4) Connection status; 5) Test results; 6) Warnings; 7) Operation instructions; 8) Other messages related to the measurement.

[0102] The right part is assembled with a power module 107 and a colorimetric sensor module 105. The power module 107 is composed of a battery and a charging circuit. The opening of the colorimetric sensor module 105 is aligned with the slot on the housing for pushing in and ejecting the sensor chip 307. The exhalation inlet of the colorimetric sensor module 105 is connected to the opening 202 on the venturi tube 200.

[0103] Now refer to Figure 7 , schematically shows an example of a top view of an embodiment of an assembled device body 100 having a disposable mask 101 and a headband 102. The headband 102 is attached to the headband connectors 701 on both sides of the device body 100, and the disposable mask 101 is assembled to the device body 100 through the mask connectors 702. The front panel 703 and the rear panel 602 of the device body 100 are assembled together to form a closed housing. The front panel 703 is designed to have corresponding windows and openings for the display 108, the LED indicator 112, the switch 115, the resetter 116 and the external port 117. The logo, model name and symbol of the product can also be screen-printed on the front panel 703. In order to control the weight of the device body 100, the front panel 703 and the rear panel 602 are made of plastic material.

[0104] Now refer to Fig. 8A , an example of a schematic diagram of an embodiment of a sensor chip 307 is shown. The micro-feature elements engraved on the sensing area are the key to evenly dispersing the sensing probe solution on the sensing area to avoid the "coffee ring" effect. Figure 8B As shown, the information of each sensor chip is encoded into a QR code, which is read by the phone / tablet / computer 103 and 120 is sent to the device body 100.

[0105] Now refer to Fig. 9 , the figure schematically shows an example of an embodiment of a wearable, integrated, self-contained device body 100 assembled with a disposable mask 101 and a headband 102.

[0106] Now refer to Fig.10 , the figure schematically shows an example of using a fully assembled self-contained wearable metabolic analyzer on a user's head to measure metabolic rate. The device body 100 has a compact structure, a disposable mask 101 covers the user's mouth and nose, and a headband 102 wraps around the user's head and firmly and stably fixes the entire self-contained wearable metabolic analyzer on the face.

[0107] Sensor performance of a self-contained wearable metabolic analyzer:

[0108] Now refer to Fig.11 , an example of a temperature reading of the thermistor 109 used by the device body 100 to monitor the ambient temperature is shown.

[0109] Now refer to Fig.13 , the figure shows an example of humidity readings of the humidity sensor 110 used by the device body 100 to monitor the ambient humidity.

[0110] Now refer to Fig.14 , the figure shows an example of a pressure reading of a barometer 111 used by the device body 100 to monitor the ambient atmospheric pressure.

[0111] Now refer to Fig.15 , the figure shows an example of the correlation between the exhalation flow measured by the flow module 104 of the device body 100 and the reference flow meter (Sensirion) with different exhalation curves.

[0112] Now refer to Fig.16 , the figure shows an example of the correlation between the concentrations of oxygen and carbon dioxide in exhaled breath measured by the colorimetric sensor module 105 on the device body 100 and the reference method.

[0113] Now refer to Fig.17 , an example of the correlation of VO2 and VCO2 measured by the device body 100 with the reference method is shown. Based on the readings from the flow module 104 and the colorimetric sensor module 105, VO2 and VCO2 are calculated according to equations (2) and (3).

[0114] Now refer to Fig.18 , an example of the correlation between REE and RQ measured by the device body 100 and the reference method is shown. REE is calculated according to equation (4) and RQ is calculated according to equation (5).

[0115] The results shown above fully demonstrate the sensor performance of the self-contained wearable metabolic analyzer ( Figure 11-Figure 15 ), and the accuracy of the O2, CO2, VO2, VCO2, REE, and RQ outputs compared to the reference method ( Figure 16-Figure 18 ).

[0116] Stability of sensor chip and venturi flowmeter:

[0117] For oxygen and carbon dioxide detection, the sensor chips of the present disclosure are highly stable for more than one year at room temperature and more than two years at low temperature. The high stability is mainly due to three reasons: 1) the sensor chips are packaged in a dry and inert environment; 2) the sensor chips are cured through a temperature-dependent process after manufacturing; and 3) batch calibration is performed after production, and the calibration coefficients of each individual sensor chip are carried using QR codes.

[0118] Regarding the stability of the venturi flowmeter, the flow calibration has been proven to remain stable for 2 years and thousands of consecutive measurements can be made without recalibration. This performance can avoid instrument maintenance issues, while existing metabolic equipment, instruments and carts need to be calibrated at least once a year (if not calibrated before each use).

[0119] Detection of other analytes:

[0120] Now refer to Fig.19 , shows an example of an acetone reading from a self-contained wearable metabolic analyzer that includes chemical sensors in addition to oxygen and carbon dioxide sensors. As mentioned earlier, acetone is an indicator of fat oxidation and is related to the respiratory quotient indicator. This parameter provides more information on whether fat oxidation in the human body is maintained at a significant level when it is detected above the typical baseline level of the human body (usually between 200ppb-1ppm).

[0121] On the one hand, the present disclosure describes a stand-alone (fully integrated), self-contained, wearable metabolic analyzer comprising: a small and lightweight sensor for simultaneously analyzing multiple metabolites (e.g., oxygen, carbon dioxide, and acetone); detecting the flow, temperature, and humidity of exhaled breath; and a device directed to measuring metabolic rate, respiratory quotient, and other metabolism-related physiological parameters.

[0122] On the other hand, the present disclosure features several innovative chemical sensing and engineering solutions that overcome the difficulties of known devices and address the need to simultaneously detect multiple metabolic parameters using a small, lightweight integrated wearable analyzer, thereby eliminating the additional instrument load and addressing personal hygiene and ease of use issues. Conventional metabolic analyzers typically use electrochemical or fluorescence sensors for oxygen (O2) detection, infrared sensors for carbon dioxide (CO2) detection, and turbine, ultrasonic, or differential pressure sensors for flow measurement. These technologies are either too heavy or too bulky for facial self-contained wearable metabolic analyzers. A miniaturized integrated sensor unit is developed in the present disclosure to measure oxygen and carbon dioxide in exhaled breath, exhaled flow, exhaled temperature, and humidity.

[0123] In one example, the device disclosed in the present invention is a mask-shaped independent, wearable, fully functional and integrated metabolic analyzer, which is used to measure resting energy expenditure (REE), respiratory quotient (RQ), oxygen consumption rate (VO2), carbon dioxide production rate (VCO2), respiratory rate (BF) and tidal volume (TV). The present disclosure includes: 1) a miniaturized, multiplexed, configurable colorimetric sensing module for measuring oxygen and carbon dioxide in exhaled air (solving size, weight and cost issues); 2) a miniaturized venturi tube and a pressure sensor-based flow module for accurately monitoring exhaled flow with less obstruction (solving comfort of use and monitoring accuracy issues); 3) a unit and method for compensating for pressure sensor signal drift, which compensates for pressure sensor signal drift caused by movement and orientation changes through a gyroscope or accelerometer built into the device body (solving ease of use issues); 4) an anti-virus / microbial measurement mechanism design, which has A disposable mask that is easy to assemble (solves hygiene issues); 5) contains sensors to monitor ambient temperature, humidity, atmospheric pressure (for user comfort and accurate climate measurement), as well as temperature and volume correction of exhaled air flow (for accurate standardized measurement); 6) various components are integrated and assembled in a compact, lightweight, and weight-balanced independent device body; 7) a communication unit and method for communicating data collected by sensors built into the device body with an external device (e.g., a phone, tablet, or computer); and 8 running software applications on the external device for data transmission and management, as well as human-machine interface.

[0124] While metabolic rate, respiratory quotient, and other physiological parameters obtained through measured carbon dioxide, oxygen, and flow are the primary parameters focused on in this disclosure, the self-contained wearable metabolic analyzer can be configured and expanded for other healthcare uses, including: 1) detecting biomarkers in exhaled breath, such as acetone (CH3COCH3), ethanol (C2H5OH), nitric oxide (NO), hydrogen (H2), methane (CH4), carbon monoxide (CO), ammonia (NH3), and volatile organic compounds (VOCs) for detecting fat oxidation, inflammation, microbiome-related gases, poisoning / smoking, esophageal or oral bacterial infections, and screening, diagnosis, and management of other diseases; 2) detecting respired carbon dioxide to assess cardiac output and stroke volume; 3) detecting forced lung parameters for assessing lung function (e.g., vital capacity parameters in chronic obstructive pulmonary disease); or 4) measuring maximum oxygen uptake and lactate threshold during exercise to assess physical activity capacity.

[0125] Certain exemplary embodiments of the present invention are described in considerable detail in this specification in order to comply with patent statutes and to provide those skilled in the art with the information necessary to apply the novel principles of the present invention and to construct and use the required exemplary components and specialized components. However, it should be understood that the present invention can be implemented by different equipment and devices, and that various modifications can be made to the equipment details and operating procedures without departing from the true spirit and scope of the present invention.

Claims

1. A self-contained metabolic analysis device configured to be worn by a user, the device comprising: The device body comprises: (i) an integrated chemical sensor module, the integrated chemical sensor module comprising a colorimetric chemical sensor chip for simultaneously measuring oxygen and carbon dioxide, (ii) a flow sensor module comprising a venturi tube for measuring exhaled air flow; a disposable mask attached to the device body and configured to allow a user to inhale ambient air through at least one inhalation check valve and exhale exhaled air into the flow sensor module through an exhalation check valve in accordance with sterile breathing, and to take a portion of the user's exhaled air and introduce it into the chemical sensor module, wherein the exhalation check valve only allows the exhaled air flow to reach the venturi tube of the flow sensor module; a headband adapted to attach the device body to the user's head; and a data transmission circuit configured to communicate with an external electronic device; wherein the venturi tube comprises a narrow constriction section, a first opening located upstream of the narrow constriction section, a second opening located proximate to the narrow constriction section, and an outlet arranged to direct the portion of the user's exhaled breath into the integrated chemical sensor module; The flow sensor module further comprises: a connector for connecting the first opening and the second opening to a pressure sensor; an expiratory flow sensor adapted to determine the expiratory flow from the output signal of the pressure sensor using a precalibrated formula; and A temperature sensor is attached to the wall of the venturi tube for measuring the exhaled air temperature.

2. The device according to claim 1, wherein the colorimetric chemical sensor chip comprises an array of sensing regions, the sensing regions comprising at least one oxygen sensing region, one carbon dioxide sensing region and one reference calibration sensing region, and wherein, The integrated chemical sensor further comprises: a detection chamber, comprising an inlet for introducing the portion of the exhaled breath of the user into the detection chamber and an outlet for guiding the portion of the exhaled breath of the user out of the detection chamber; a light emitting diode light source, located on a first side of the detection chamber to illuminate the colorimetric chemical sensor chip; a light detection unit located at a second side of the detection chamber, opposite to the first side, to collect light from the colorimetric chemical sensor chip; and An electronic circuit includes a conditioning circuit, an amplifier, and a processor, and is configured to receive electronic information from the light detection unit and determine the light absorbance of oxygen and carbon dioxide at a single wavelength.

3. The device according to claim 1, wherein: The data transmission circuit is configured to wirelessly communicate with an external electronic device selected from a mobile phone, a computer or a printer having a wireless function.

4. The apparatus according to claim 1, further comprising: An encoder for encoding the calibration parameters of the colorimetric chemical sensor chip in a QR code, a QR code reader, and a QR code processor adapted to determine measured oxygen and carbon dioxide concentrations from the QR code.

5. The apparatus of claim 1, wherein the at least one inhalation check valve comprises a plurality of inhalation check valves, and the disposable mask further comprises: an exhalation hole, having the exhalation one-way valve, located in the middle of the disposable mask; and At least two inhalation holes, each of which has the inhalation one-way valve and is located around the exhalation hole; means for providing an airtight connection to the body of the device; and Means of providing an airtight and comfortable connection to the user's face.

6. The device according to claim 5, wherein: The diameter of the exhalation hole is between 20 mm and 40 mm.

7. The device according to claim 1, wherein: The integrated chemical sensor module has a geometry configured to provide efficient mixing of the breath sample and to provide symmetrical flow distribution.

8. The device according to claim 1, wherein: The device body further includes a humidity sensor for monitoring ambient humidity levels, and the device is configured to use an output of the humidity sensor to compensate for ambient humidity in determining exhalation flow.

9. The device according to claim 1, wherein: The device body further includes a barometer, and the device is configured to use an output of the barometer to compensate for ambient pressure in determining exhaled air flow.

10. The device according to claim 1, wherein: The device body further includes a gyroscope for detecting the orientation of the device body in determining the exhalation flow rate.

11. The device according to claim 1, wherein: The device body further includes a barometer and a temperature sensor, and the flow sensor module further includes a converter, which is suitable for converting the measured exhalation flow into an exhalation flow under standard pressure and temperature conditions using the outputs of the barometer and the temperature sensor.

12. The device according to claim 1, wherein: The device body further includes a gyroscope configured to detect an orientation of the device body, and the flow sensor module uses data from the gyroscope to correct for the effects of gravity on the pressure sensor using an error correction algorithm.

13. The device according to claim 1, wherein: The diameter of the narrow contraction section of the Venturi tube is between 3 mm and 25 mm.

14. The device according to claim 1, wherein: The device is configured to determine oxygen consumption rate (VO2) and carbon dioxide production rate (VCO2) using the integrated chemical sensor module and the flow sensor module, and is configured to determine resting energy expenditure (REE) using the oxygen consumption rate (VO2) and carbon dioxide production rate (VCO2) according to a weir flow equation, and to determine a respiratory quotient (RQ).

15. The device according to claim 1, wherein: The apparatus is configured to determine an oxygen consumption rate (VO2) using the integrated chemical sensor module and the flow sensor module, and is configured to determine a maximum oxygen consumption rate (VO2 Max) based on the oxygen consumption rate (VO2).

16. The device according to claim 1, wherein The colorimetric chemical sensor chip is configured to detect at least one chemical analyte selected from acetone, ethanol, ammonia, hydrogen, methane, carbon monoxide, and nitric oxide.

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