Ingestion-type sensor capsules for in-situ real-time detection of gas molecules in the gastrointestinal tract

Abstract

This invention discloses an ingestion-type sensing capsule for in-situ real-time detection of gas molecules in the gastrointestinal tract. The device includes a capsule structure, a non-dispersive infrared gas sensor, and a capsule detection circuit. The non-dispersive infrared gas sensor detects target gases in the gastrointestinal environment and outputs a small-amplitude current signal reflecting gas concentration. The capsule detection circuit is connected to the non-dispersive infrared gas sensor and converts the small-amplitude current signal into a large-amplitude voltage signal, and further into a digital signal. The capsule detection circuit and the non-dispersive infrared gas sensor are assembled in the capsule structure, and an external receiver is wirelessly connected to the capsule detection circuit to receive the digital signal. This invention provides a practical ingestion-type detection platform capable of accurately detecting gas concentration in the gastrointestinal tract in real time, offering a new auxiliary means for the clinical detection and treatment of gastrointestinal diseases.

Description

Technical Field

[0001] This invention relates to non-spectral infrared optical detection technology, and more particularly to an ingestion-type sensing capsule for in-situ real-time detection of gas molecules in the gastrointestinal tract. Background Technology

[0002] The gastrointestinal tract contains many substances related to human metabolism and contains rich physiological information. For example, various gases in the intestines, including hydrogen (H2), methane (CH4), carbon dioxide (CO2), and various trace gases, are important markers of intestinal health and can serve as indicators of gastrointestinal diseases such as inflammatory bowel disease and irritable bowel syndrome. Currently, commonly used clinical testing methods, such as breath tests and body temperature measurements, generally have the advantage of being non-invasive, but their accuracy is significantly affected by interference signals. While methods such as intestinal tube collection and gas collection are highly accurate, the testing process can cause discomfort and pain to patients. Non-dispersive infrared technology, an application of infrared spectroscopy, is based on the characteristic that gas molecules absorb infrared light of specific wavelengths. It analyzes gas concentration by detecting changes in the intensity of infrared light after detecting the gas being tested. It has advantages such as high specificity, rapid response, and high stability, making it very suitable for real-time monitoring of gastrointestinal gas concentration. Summary of the Invention

[0003] The purpose of this invention is to address the above-mentioned problems by providing an ingestion-type sensing capsule for in-situ real-time detection of gas molecules in the gastrointestinal tract, which directly detects gas molecules in the gastrointestinal tract using a non-invasive method.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows: As a first aspect, the present invention provides an ingestion-type sensing detection capsule for in-situ real-time detection of gas molecules in the gastrointestinal tract. The ingestion-type sensing detection capsule includes a capsule structure, a capsule detection circuit, a non-dispersive infrared gas sensor, and an external receiver. The capsule detection circuit and the non-dispersive infrared gas sensor are assembled in the capsule structure. The capsule detection circuit includes a digital signal transmission circuit substrate, a flexible substrate, and an analog signal transmission circuit rigid substrate connected in sequence. The digital signal transmission circuit rigid substrate is equipped with an MCU module, a light source driving module, and a communication module. The analog signal transmission circuit rigid substrate is equipped with a self-adjusting zero-transimpedance amplifier, a bandpass filter, a battery, and a power management module.

[0005] The MCU module is used to send control commands, drive the non-dispersive infrared gas sensor to work through the light source driving module, and receive analog signals sent by the self-adjusting zero-transimpedance amplifier and bandpass filter, perform analog-to-digital conversion, calculate the signal amplitude, and transmit it to the communication module. The non-dispersive infrared gas sensor is used to detect target gases in the gastrointestinal environment and output a small-amplitude current signal reflecting the gas concentration, which is connected to the self-adjusting zero-transimpedance amplifier and bandpass filter. The self-adjusting zero-transimpedance amplifier and bandpass filter are used to convert the small-amplitude current signal into a large-amplitude voltage signal. The communication module is used to wirelessly transmit the signal amplitude calculated by the MCU module to the external receiver.

[0006] Furthermore, the non-spectral infrared gas sensor includes an infrared light source, a detection chamber, and an infrared detector; the infrared light source is connected to a digital signal transmission circuit substrate, and the infrared detector is connected to an analog signal transmission circuit substrate; the infrared light source is used to radiate infrared light into the detection chamber after being driven by the MCU module, the target gas in the detection chamber interacts with the infrared light and is absorbed, illuminating the infrared detector, the infrared detector receives the infrared light signal and converts it into a small-amplitude current signal that reflects the concentration of the target gas.

[0007] Furthermore, the capsule detection circuit is fabricated using a rigid-flexible composite printed circuit board process. The flexible substrate is provided with wires connecting the analog signal transmission circuit and the digital signal transmission circuit. The light source driving module and the communication module are electrically connected to the MCU module on the rigid substrate of the digital signal transmission circuit via copper foil wires. The self-adjusting zero-transimpedance amplifier and the bandpass filter are electrically connected on the substrate of the analog signal transmission circuit via copper foil wires. The bandpass filter is electrically connected to the MCU module via the flexible substrate. The battery and the power management module are electrically connected on the rigid substrate of the analog signal transmission circuit via copper foil wires. Subsequently, the battery and the power management module are electrically connected to the MCU module, the light source driving module, the communication module, the self-adjusting zero-transimpedance amplifier, and the bandpass filter.

[0008] Furthermore, the MCU module, light source driver module, and communication module are configured for low power consumption to extend the system's operating time.

[0009] Furthermore, the capsule structure includes an analog signal transmission circuit chamber, a sensor chamber, and a digital signal transmission circuit chamber connected in sequence; the sensor chamber is provided with a grid for gas passage, and the grid is coated with a waterproof and breathable membrane, which is a dimethylsiloxane (PDMS) membrane, to block liquids and allow gas to pass through; the digital signal transmission circuit substrate and the analog signal transmission circuit rigid substrate are respectively distributed on the digital signal transmission circuit chamber and the analog signal transmission circuit chamber; the infrared light source and the infrared detector are respectively distributed on the digital signal transmission circuit chamber and the analog signal transmission circuit chamber.

[0010] Furthermore, the external receiver is wirelessly connected to the capsule detection circuit and has host computer application software on it. The host computer application software is used to receive and process digital signals from the ingestible sensor detection capsule and display them in real time.

[0011] Furthermore, the external receiver includes one or more smartphones or personal computers.

[0012] As a second aspect, the present invention provides an application of the ingestion-type sensing detection capsule in in-situ real-time detection of gas molecules in the gastrointestinal tract, namely, a method for in-situ real-time detection of gas molecules in the gastrointestinal tract, the method being implemented in the detection device described in the first aspect (hereinafter referred to as the ingestion capsule), the method comprising:

[0013] S1, Gas sensor characteristic test;

[0014] Different concentrations of a single gas are introduced into a sealed container, and the gas concentration is detected using the ingestion capsule. A fitting curve for the gas sensor is then plotted based on this. Nitrogen and a single-concentration gas are alternately introduced into the sealed container 10 times, and the gas concentration is detected using the ingestion capsule. A cyclic detection curve for the gas sensor is then plotted based on this. In air, the gas concentration is detected over a long period using the ingestion capsule, and a long-term stability test result graph for the gas sensor is then plotted based on this. Mixed gases of different concentrations are introduced into a sealed container, and the gas concentration is detected using the ingestion capsule. A cross-response test result graph for the gas sensor is then plotted based on this.

[0015] S2, Gas sensor anti-interference test;

[0016] Nitrogen gas with different relative humidities is introduced into a sealed container, and the gas concentration is detected using the ingestion capsule. The humidity interference test results of the gas sensor are plotted based on this. The sealed container is placed in a water bath at different temperatures, and a single concentration of gas is introduced into the container. The gas concentration is detected using the ingestion capsule. The temperature interference test results of the gas sensor are plotted based on this.

[0017] S3, Characterization of communication performance of ingestible capsules;

[0018] The ingestion capsules were placed in an open space, in the center of a beaker filled with water, and in the center of a bucket of water. A handheld spectrum analyzer was used to detect the signal strength at different distances from the ingestion capsules. The ingestion capsules were then rotated at different angles to continue detecting the signal strength.

[0019] S4, Gas sensor performance calibration;

[0020] Different concentrations of gas were introduced into a sealed container containing an ingestion capsule, and the gas concentration was detected using the ingestion capsule, with a commercial gas sensor used for comparison.

[0021] S5, Detection of gas concentration in the gastrointestinal tract of animals using an ingestible capsule while the animal is awake:

[0022] While the animal is awake, the ingested capsule is delivered into the gastrointestinal tract through a fistula to detect the gas concentration, and the detected gas concentration parameters are transmitted wirelessly to an external receiver.

[0023] The present invention has the following beneficial effects:

[0024] Miniaturization of the capsule detection circuit was achieved using rigid-flex printed circuit board technology, enabling its integration within the capsule structure. The capsule detection circuit is designed as two circular circuit boards with a diameter of 10 mm. The ingestible capsule can stably measure gas molecules in the gastrointestinal environment for extended periods, offering advantages such as rapid response and high resolution. This lays the foundation for real-time in-situ health data analysis at the molecular level under different physiological and pathological states within the intestine. Experiments on large animals have confirmed the ingestible capsule's ability to perform real-time in-situ gas concentration detection in the gastrointestinal tract. After detection, the ingestible capsule can be recovered. Its capsule detection circuit and gas sensor components can be reused after necessary processing.

[0025] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0027] Figure 1 This is a system diagram of an ingestible capsule device for detecting gastrointestinal gas concentration in an embodiment of the present invention;

[0028] Figure 2 This is a structural diagram of the ingestible capsule in an embodiment of the present invention;

[0029] Figure 3 This is a structural diagram of the capsule detection circuit in an embodiment of the present invention;

[0030] Figure 4 This is a structural diagram of the non-spectral infrared gas sensor in an embodiment of the present invention;

[0031] Figure 5 These are interface diagrams of personal computer application software and smartphone application software in embodiments of the present invention;

[0032] Figure 6 This is a flowchart of the low-power configuration of the ingestible capsule in an embodiment of the present invention;

[0033] Figure 7 This is a flowchart illustrating the process of an ingestible capsule for detecting gastrointestinal gas concentration in an embodiment of the present invention.

[0034] Figure 8 These are the response curves of the CO2 and CH4 gas sensors in this embodiment of the invention for different concentrations of CO2 and CH4, where (a) is the response curve for CO2 and (b) is the response curve for CH4.

[0035] Figure 9 These are the fitting curves of the CO2 and CH4 gas sensors in the embodiments of the present invention, where (a) is the CO2 response and (b) is the CH4 response;

[0036] Figure 10 These are the cyclic detection curves of the CO2 and CH4 gas sensors in the embodiments of the present invention, wherein (a) is the cyclic detection curve of the CO2 gas sensor and (b) is the cyclic detection curve of the CH4 gas sensor.

[0037] Figure 11 This is a graph showing the long-term stability test results of the CO2 and CH4 gas sensors in this embodiment of the invention;

[0038] Figure 12 The figures shown are cross-response test results of CO2 and CH4 gas sensors in the embodiments of the present invention, where (a) is the cross-response test of CO2 gas sensor and (b) is the cross-response test of CH4 gas sensor.

[0039] Figure 13 This is a graph showing the humidity interference test results of the CO2 gas sensor in this embodiment of the invention.

[0040] Figure 14 This is a graph showing the temperature interference test results of the CO2 gas sensor in this embodiment of the invention;

[0041] Figure 15 This refers to the signal strength received by the ingestible capsule in different environments and at different distances in the embodiments of the present invention;

[0042] Figure 16 This refers to the signal strength received by the ingestible capsule at different angles in this embodiment of the invention;

[0043] Figure 17 This is a comparison chart of the detection results of the ingestible capsule and the commercial sensor in the embodiments of the present invention, wherein (a) is a comparison of the detection results of CO2 and (b) is a comparison of the detection results of CH4;

[0044] Figure 18 These are the detection results of CO2 and CH4 gas concentrations in the goat rumen of the ingestible capsule in this embodiment of the invention.

[0045] In the diagram: 0. Ingestion capsule; 1. Capsule structure; 2. Capsule detection circuit; 3. Non-spectral infrared gas sensor; 4. Host computer application software; 11. Analog signal transmission circuit chamber; 12. Digital signal transmission circuit chamber; 13. Sensor chamber; 14. Waterproof and breathable membrane; 21. Rigid substrate for digital signal transmission circuit; 21. MCU module; 211. Light source driving module; 212. Communication module; 213. Flexible substrate; 22. Rigid substrate for analog signal transmission circuit; 23. Self-adjusting zero-transimpedance amplifier; 231. Bandpass filter; 232. Battery; 233. Power management module; 234. Infrared light source; 31. Detection gas chamber; 32. Infrared detector; 33. Personal computer application software; 41. Smartphone application software; 42. Detailed Implementation

[0046] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0047] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0048] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0049] like Figure 1 As shown, this embodiment of the invention provides an ingestion-type sensor detection capsule for detecting gas concentration in the gastrointestinal tract, comprising: an ingestion capsule 0 and an external receiver. The ingestion capsule 0 includes a capsule structure 1, a capsule detection circuit 2, and a non-dispersive infrared gas sensor 3. The non-dispersive infrared gas sensor 3 is used to detect the gas concentration in the gastrointestinal environment and outputs a small-amplitude current signal that reflects the gas concentration. The capsule detection circuit 2 is electrically connected to the non-dispersive infrared gas sensor 3 and is used to convert the small-amplitude current signal into a large-amplitude voltage signal, and further into a digital signal. The capsule structure 1 includes an analog signal transmission circuit chamber 11, a digital signal transmission circuit chamber 12, a sensor chamber 13, and a waterproof and breathable membrane 14. The external receiver is wirelessly connected to the capsule detection circuit 2 and is used to receive the digital signal.

[0050] As can be seen from the above embodiments, this application employs an ingestible capsule design to achieve miniaturization of the sensor and circuitry, enabling them to be assembled within a very small capsule structure. The ingestible capsule can be immersed in a liquid environment for long-term stable measurement of gas concentration, thus helping to solve the problem of detecting gastrointestinal gas concentration in clinical, non-anesthetic conditions. Experiments on large animals have confirmed that the ingestible capsule does not cause wounds during gastrointestinal measurement and requires no anesthesia. After detection, the ingestible capsule can be recycled. Its capsule detection circuit 2 and non-dispersive infrared gas sensor 3 can be reused after necessary processing. Therefore, the device and method for detecting gastrointestinal gas concentration using a capsule device can achieve in-situ, continuous, and real-time detection of gas molecules in the gastrointestinal tract, providing a new auxiliary means for the clinical detection and treatment of gastrointestinal diseases.

[0051] In this example, the capsule structure 1 is manufactured using resin (Future R4600, Shenzhen Future Factory Technology Co., Ltd., China) through 3D printing. Figure 2As shown, the capsule structure 1 includes an analog signal transmission circuit chamber 11, a digital signal transmission circuit chamber 12, a sensor chamber 13, and a waterproof and breathable membrane 14. The sensor chamber has a grid for gas passage; the grid is coated with a dimethylsiloxane (PDMS) membrane, i.e., the waterproof and breathable membrane 14, which has high permeability to gas while blocking liquid.

[0052] The capsule detection circuit 2 and the non-spectral infrared gas sensor 3 are assembled in the capsule structure 1. The detection chamber 32 is located in the middle of the entire capsule structure 1. The infrared light source 31 and the infrared detector 33 can be distributed on the digital signal transmission circuit chamber 12 and the analog signal transmission circuit chamber 11, respectively, electrically connected through a flexible substrate and sealed with adhesive. The analog signal transmission circuit chamber 11 and the digital signal transmission circuit chamber 12 are located at opposite ends of the chamber. After assembly, the analog signal transmission circuit chamber 11, the digital signal transmission circuit chamber 12, and the sensor chamber 13 can be connected by an interference fit and the interface is sealed with hot melt adhesive. The total height of the capsule structure 1 is 23 mm. The sensor chamber 13 is designed as a cylinder with an inner diameter of 14.5 mm and an outer diameter of 10.5 mm, and a height of 7.5 mm. The two circular surfaces of the sensor chamber 13 are designed with recesses and circular light paths, which can embed the light source and detector into the recesses and radiate infrared light into the chamber through the light paths.

[0053] As can be seen from the above embodiments, the capsule-shaped shell design of this application allows the size and shape of the ingestible capsule 0 to conform to the gastrointestinal tract, preventing damage when passing through narrow parts of the gastrointestinal tract. Furthermore, the grid on the sensor chamber used for gas passage is coated with a waterproof and breathable membrane 14, which can block liquids to prevent short circuits in the capsule detection circuit, while allowing small gas molecules to pass through, thus enabling gas concentration detection.

[0054] like Figure 3 As shown, in one possible implementation, the capsule detection circuit 2 is designed as two circular circuits with a diameter of 10 mm. The capsule detection circuit 2 is fabricated using a rigid-flexible composite printed circuit board process and includes a rigid substrate 21 for digital signal transmission circuits, a flexible substrate 22, and a rigid substrate 23 for analog signal transmission circuits.

[0055] Furthermore, the light source driving module 212 and communication module 213 are electrically connected to the MCU module 211 on the rigid substrate 21 of the digital signal transmission circuit via copper foil wires. The self-zeroing transimpedance amplifier 231 and bandpass filter 232 are electrically connected on the analog signal transmission circuit substrate 23 via copper foil wires. The self-zeroing transimpedance amplifier 231 and bandpass filter 232 are electrically connected to the MCU module 211 via a flexible substrate 22. The battery 233 and power management module 234 are electrically connected on the rigid substrate 23 of the analog signal transmission circuit via copper foil wires. Then, the battery 233 and power management module 234 are electrically connected to the MCU module 211, light source driving module 212, communication module 213, self-zeroing transimpedance amplifier 231 and bandpass filter 232.

[0056] Furthermore, the rigid substrate 21 of the digital signal transmission circuit has a light source driving module 212 and a program download interface welded to the front, and an MCU module 211 and a communication module 213 welded to the back.

[0057] In one possible implementation, the light source driving module 212 can use a low-voltage field-effect transistor AO3400 (Alpha Omega Semiconductor, USA), and the external capacitors and resistors can be surface-mount components in 0201 packages; the program download interface can be an FPC connector (10-pin, 0.5mm pitch); the MCU module 211 can use an MSP430FR2355 (Texas Instruments, USA) as the main control chip for the capsule detection circuit, and the external capacitors and resistors can be surface-mount components in 0201 packages; the communication module 213 consists of a wireless communication chip (MAX1472, Analog Devices, USA) and a crystal oscillator (13.56MHz surface-mount crystal oscillator, 3.2×2.5mm), and the external capacitors, resistors, and inductors can be surface-mount components in 0201 packages.

[0058] Furthermore, the rigid substrate 23 of the analog signal transmission circuit has some components of the bandpass filter 232 and the power management module 234 soldered to its front side, and some components of the self-zeroing transimpedance amplifier 231, the battery 233, and the power management module 234 soldered to its back side. Through copper foil wires embedded in the rigid substrate, these components can achieve an orderly electrical connection.

[0059] In one possible implementation, the bandpass filter 232 can be an AD8606 (Analog Devices, Inc., USA), and the external capacitors and resistors can be surface-mount components in 0201 packages; the battery 233 can be a ZCLP1500 lithium-ion battery (Shenzhen Zhongshun New Energy Battery Co., Ltd., China); the power management module 234 can be an AD8605 (Analog Devices, Inc., USA) or an LP5907 low-noise, low-dropout linear regulator (Texas Instruments, Inc., USA), and the external capacitors and resistors can be surface-mount components in 0201 packages; the self-adjusting zero-transimpedance amplifier 231 can also be an AD8606 (Analog Devices, Inc., USA), and the external capacitors and resistors can be surface-mount components in 0201 packages.

[0060] Furthermore, the flexible substrate 22 is used to connect the rigid substrate 21 of the digital signal transmission circuit and the rigid substrate 23 of the analog signal transmission circuit.

[0061] like Figure 4 As shown, in one possible implementation, the non-spectral infrared gas sensor 3 includes an infrared light source 31, a detection chamber 32, and an infrared detector 33. The infrared light source 31 is connected to a digital signal transmission circuit substrate 21, and the infrared detector 33 is connected to an analog signal transmission circuit substrate 23.

[0062] Furthermore, the infrared light source 31 can be selected from Lms43LED and Lms34LED (LED Microsensor NT, Russia) packaged in CS3020, and used as the light source for CO2 and CH4 gas sensors, respectively; the infrared detector 33 can be selected from Lms43PD and Lms36PD (LED Microsensor NT, Russia), and used as the infrared detector components for CO2 and CH4 sensors, respectively; the detection chamber 32 is provided by the optical path in the sensor chamber 13.

[0063] like Figure 5 As shown, the host computer application software 4 includes a personal computer application software 41 running on the Windows platform of a personal computer and a smartphone application software 42 running on the Android platform of a smartphone. In this specific embodiment, the host computer software 4 mainly refers to the smartphone application software 42 running on the Android platform of a smartphone.

[0064] In one possible implementation, the personal computer application software 41 running on the Windows platform of a personal computer is developed using the Microsoft Visual Studio 2019 development tool, and the smartphone application software 42 running on the Android platform of a smartphone is developed using the Android Studio v3.2 development tool.

[0065] like Figure 6 As shown, in one possible implementation, the software design of the main working modules of the capsule detection circuit can adopt a low-power configuration, including an MCU module 211, a light source driving module 212, and a communication module 213. After the MCU module powers on and resets, completing initialization, it enters low-power mode. Subsequently, a timer starts counting, and after each cycle (20s), it exits low-power mode and enters the working state, driving the light source to work and performing ADC sampling. When the sampling time reaches 2s, the light source is turned off and sampling stops, and the communication module is started. After sending the processed sampled data, the communication module is turned off, and it re-enters low-power mode, repeating the above process.

[0066] As can be seen from the above embodiments, this application significantly reduces the power consumption of the ingestible capsule through low-power software design, extends its working time in the human digestive tract, and thus meets the need for real-time detection of gas molecules throughout the human digestive tract.

[0067] In one possible implementation, the workflow of the ingestion-type sensing capsule for detecting gastrointestinal gas concentration is as follows: Figure 7 As shown. After the battery 233 (a lithium battery is used in this example) is connected to the capsule detection circuit 2, the power management module 234 adjusts the battery output to power the entire capsule detection circuit 2. The MCU module 211 in the capsule detection circuit 2 starts working, sending control commands to apply a fixed-frequency square wave signal to the mid-infrared LED, i.e., the infrared light source 31, driving the mid-infrared LED to work in the linear region. The mid-infrared LED radiates infrared light into the gas chamber, interacts with the gas to be measured in the gas chamber and is absorbed, and then illuminates the mid-infrared PD, i.e., the infrared detector 33. The mid-infrared PD converts the received light signal into a small-amplitude AC signal in the μA range. After being processed by the signal processing module, i.e., the self-adjusting zero-transimpedance amplifier 231 and the bandpass filter 232, the small-amplitude AC signal is extracted from the large-amplitude DC signal, amplified to several hundred mV, and then input into the MCU module for analog-to-digital conversion to calculate the signal amplitude. The result is then transmitted to the communication module 213 for wireless communication to the external receiver. The external receiver can be a personal computer or a smartphone.

[0068] Another object of the present invention is to provide a method for adjusting gastrointestinal gas concentration using the above-described capsule device, comprising the following steps:

[0069] S1, Gas sensor characteristic test:

[0070] Different concentrations of carbon dioxide gas were introduced into a sealed container equipped with a CO2 sensor for gas concentration detection. The gas concentration detection steps included: introducing a gas of one concentration, and after the reading on the ingestion capsule stabilized, detecting for 2 minutes. After detection, the container was purged by introducing pure nitrogen gas, and after the reading on the ingestion capsule stabilized again, detecting for 2 minutes. The above steps were repeated, introducing mixed gases with CO2 concentrations of 5%, 10%, 15%, 20%, 25%, and 30% in sequence. After completing the CO2 test, mixed gases with CH4 concentrations of 4%, 20%, 30%, 40%, and 50% were prepared and introduced into a sealed container equipped with a CH4 sensor. The sensor's response curve and fitting curve were then plotted.

[0071] Mixed gases with CO2 concentrations of 0% and 30% and CH4 concentrations of 0% and 20% were introduced into sealed containers containing CO2 and CH4 sensors, respectively, and 10 alternating detections were performed. The cyclic detection curves of the sensors were then plotted.

[0072] The CO2 and CH4 sensors were used to continuously detect the air (CO2 concentration of approximately 0.03% and CH4 concentration of approximately 0) for 4.5 hours, and the long-term stability test results of the sensors were plotted.

[0073] 5% CO2 and 50% CH4 were prepared and detected using a CO2 gas sensor; 4% CH4 and 30% CO2 were prepared and detected using a CH4 gas sensor. The detection time was 3 minutes for both. Their output responses were compared, and the cross-response test results of the sensors were plotted.

[0074] S2, Gas sensor anti-interference test:

[0075] Nitrogen gas with relative humidity of 30%, 50%, and 70% was introduced into a sealed container equipped with a CH4 gas sensor. The gas was tested for each humidity for 3 minutes. The output amplitude of the sensor was observed to see if it would change. The humidity interference test results of the sensor were plotted based on this.

[0076] A sealed container equipped with a CO2 gas sensor was heated in a water bath at 40℃, 45℃, and 50℃. The operating temperature of the gas sensor was controlled by adjusting the temperature of the water bath. A 10% concentration of CO2 was introduced into the sealed container. The mixed gas was detected for 3 minutes at each temperature, and the changes in the output amplitude were observed. The temperature interference test results of the sensor were then plotted.

[0077] S3, Characterization of ingestible capsule communication performance:

[0078] The ingestible capsule was fixed in an open area, and the signal strength at a frequency of 315MHz was measured at different distances from the capsule using a handheld spectrum analyzer. Three measurements were taken at each distance. Subsequently, the capsule was placed at the center of a beaker filled with water (100mm in diameter) and at the center of a bucket filled with water (300mm in diameter, simulating the diameter of a human abdomen), and the above steps were repeated. The test results were plotted.

[0079] A 300mm diameter bucket was used to simulate the human gastrointestinal environment. An ingestible capsule was placed in the center of the bucket, and a spectrum analyzer was used to detect the signal strength emitted by the capsule at a distance of 0.5m. The capsule was rotated at different angles, and the signal strength was measured three times at each angle. The results were then plotted.

[0080] S4, Gas sensor performance calibration:

[0081] Nitrogen, 20% CO2, 30% CO2, and 20% CO2 and nitrogen were sequentially introduced into a sealed container. A CO2 sensor and a commercial CO2 sensor were used simultaneously to detect each concentration of the gas mixture. After each gas concentration change, the readings of both devices were allowed to stabilize before a 3-minute detection period. Next, a CH4 sensor and a commercial CH4 sensor were placed in the same sealed container, and nitrogen, 15% CH4, 30% CH4, 15% CH4 and nitrogen were sequentially introduced into the container. The above steps were repeated, and gas concentration response curves were plotted.

[0082] S5, Detection of gas concentration in the gastrointestinal tract of animals using an ingestible capsule while the animal is awake:

[0083] In vivo assessments were conducted using goats. After undergoing a fistula surgery, the goats were placed in a separate enclosure for observation for two weeks, receiving excellent care during this period. Before the experiment, the goats were fasted for three days. After the fasting period, an ingestible capsule was inserted into the goat's rumen through the fistula, and the cap was tightened to isolate the rumen from the external environment. The OOK RF receiver module RFM217B was connected to a personal computer, receiving data from the ingestible capsule and displaying it in real-time. With the goats fasting, the CO2 concentration in the rumen was measured using the ingestible capsule for approximately 30 minutes. Afterward, the ingestible capsule was removed, sterilized, and the battery disconnected, and the goats were fed. After the goats finished eating, the batteries in the ingestible capsule were replaced, resealed, sterilized, and reinserted into the goat's rumen through the fistula. The CO2 concentration in the rumen was measured using the ingestible capsule approximately 2.5 hours after the goats finished eating. Approximately one hour after the measurement, headair was collected from the goat's rumen using a micro-peristaltic pump. Approximately 2 hours after the initial testing, headspace air and rumen fluid were collected from the goat's rumen. After collection, testing continued for approximately 30 minutes to complete one in vivo assessment experiment. The goats were then fed normally for one week, followed by a three-day fast, and the above steps were repeated using a CH4-sensor capsule.

[0084] The present invention will be further described in detail below through examples.

[0085] Example 1:

[0086] S1, Gas sensor characteristic test:

[0087] Figure 8 and Figure 9 The response curves and fitting curves of the two gas sensors are presented respectively. Both gas sensors respond well to different concentrations of target gases, and the change in sensor response gradually decreases as the concentration of the analyte gas increases. It can be seen from the figure that the sensitivity of the CO2 sensor is higher than that of the CH4 sensor. The coefficient of determination R of the CO2 sensor is... 2 The coefficient of determination R of the CH4 sensor is approximately 0.986. 2 The value is approximately 0.996, indicating that the fitting curve of the CH4 sensor is more consistent with the actual data. From this figure, we can see the relationship between the response of the two gas sensors and the gas concentration, and thus calculate the gas concentration detected by the non-spectral infrared gas sensor 3 using the response voltage reading.

[0088] Figure 10The results of 10 alternating detections using CO2 and CH4 sensors in a mixed gas are presented. The CO2 sensor exhibits an amplitude response with a standard deviation of only 32.28 mV at 0% concentration, a relative standard deviation of only 0.029%. At 30% concentration, its amplitude response standard deviation is 289.42 mV, with a relative standard deviation of only 0.33%. The CH4 sensor shows an amplitude response standard deviation of only 256.73 mV at 0% concentration, a relative standard deviation of only 0.11%. At 30% concentration, its amplitude response standard deviation is 409.21 mV, with a relative standard deviation of only 0.18%. These results demonstrate that both the CO2 and CH4 sensors maintain good operating characteristics even under significant variations in gas concentration.

[0089] The long-term stability test results of the sensor are as follows: Figure 11 As shown, the CO2 sensor's standard deviation was 843.25 mV over a 4.5-hour detection period, with a relative standard deviation of only 0.64%. The CH4 sensor's standard deviation was 848.77 mV over the same period, with a relative standard deviation of only 0.69%. The detection results of both gas sensors showed little fluctuation, confirming that the gas sensors possess good long-term stability; their response does not change significantly during prolonged continuous detection.

[0090] Sensor cross-response test results are as follows Figure 12 As shown, high concentrations of CH4 only caused a 0.327% change in the CO2 gas sensor, which is comparable to the change value obtained in the long-term stability test. This is considered normal fluctuation in the sensor's reading, and this change accounts for only 1.76% of the change in the CO2 sensor response caused by normal concentrations of CO2, which is negligible. Similarly, high concentrations of CO2 only caused a 0.0680% change in the CH4 gas sensor, which is smaller than the change value obtained in the long-term stability test, also considered normal fluctuation in the sensor's reading. Furthermore, this change accounts for only 5.42% of the change in the CH4 sensor response caused by normal concentrations of CH4, which is also negligible. This confirms that high concentrations of CH4 gas do not cause significant changes in the amplitude response of the CO2 sensor, nor do high concentrations of CO2 gas cause significant changes in the amplitude response of the CH4 sensor, and there is no cross-interference between the two gases.

[0091] S2, Gas sensor anti-interference test:

[0092] Humidity interference test results are as follows Figure 13As shown in the figure, humidity changes have almost no effect on the output amplitude of the CH4 gas sensor. Among the detection results of the three humid gases, the largest deviation is in the output amplitude at a relative humidity of 50%, with a deviation of 412.78 mV and a relative deviation of 1.43%, which can be considered negligible.

[0093] Temperature interference test results are as follows Figure 14 As shown in the figure, temperature and output amplitude are negatively correlated. As the temperature increases from 40℃ to 50℃, the output amplitude decreases from 57023mV to 40590mV, indicating that temperature has a certain impact on the output amplitude of the gas sensor.

[0094] S7, Characterization of ingestible capsule communication performance:

[0095] Figure 15 This study demonstrates the use of a spectrum analyzer to test the signal strength transmitted by the ingestible capsule at different distances and in different environments. The results show that in air at a distance of 10m, a signal strength of approximately -72dBm can still be detected. In water, when the ingestible capsule penetrates a water layer of 50mm and 150mm, the signal strength attenuates to -43.9dBm and -46.2dBm, respectively. When no water penetration is required, the signal strength is -36.5dBm. In an experiment simulating the ingestible capsule transmitting wireless communication signals within the human gastrointestinal tract using a 300mm diameter bucket filled with water, the detected signal strength only drops below -90dBm at a distance of 10m. These results indicate that the ingestible capsule can still detect signals within a range of approximately 10m when operating in the human gastrointestinal tract, meeting application requirements.

[0096] Figure 16 This study demonstrates the use of a spectrum analyzer to test the signal strength transmitted by ingestible capsules placed at different angles. The results show that while the signal strength detected by the spectrum analyzer varied with the capsule's rotation angle, none fell below -60 dBm. Therefore, the rotation of the ingestible capsule within the gastrointestinal tract does not significantly affect signal reception.

[0097] S8, Gas sensor calibration test:

[0098] Test results are as follows Figure 17 As shown, the CO2 sensing capsule exhibits good consistency with the detection results of commercial CO2 sensors, with a maximum measurement deviation of 3.33% CO2 concentration and a relative deviation of 11.5%. The CH4 sensing capsule also shows good consistency with commercial CH4 sensors, with a maximum deviation of 4.24% CH4 concentration and a relative deviation of 12.8%. Furthermore, the ingestion capsule demonstrates a faster response speed and higher concentration resolution than commercial sensors.

[0099] S9, Detection of gas concentration in the gastrointestinal tract of animals using an ingestible capsule while the animal is awake:

[0100] Test results are as follows Figure 18 As shown, the curve represents the data measured by the capsule system, while the scatter plot represents the gas concentration of air taken from the top of the goat's rumen by gas chromatography. The results indicate that the CO2 and CH4 concentrations in the rumen of goats remain at relatively low levels during fasting. After the goats finish feeding, the CO2 and CH4 concentrations in the rumen gradually increase, reaching their highest concentrations approximately 1 hour after feeding, then decreasing and gradually stabilizing, which is largely consistent with actual changes. This demonstrates that the capsule system constructed in this invention can effectively detect the gas concentration in the rumen of ruminants, and that the detection results have certain reference value.

[0101] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0102] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. An ingested sensor capsule for in-situ real-time detection of gas molecules in the gastrointestinal tract, characterized in that, The capsule type sensing detection capsule comprises a capsule structure (1), a capsule detection circuit (2), a non-spectroscopic infrared gas sensor (3), and an extracorporeal receiving end; the capsule detection circuit (2) and the non-spectroscopic infrared gas sensor (3) are assembled in the capsule structure (1); the capsule detection circuit (2) comprises a digital signal transmission circuit rigid substrate (21), a flexible substrate (22), and an analog signal transmission circuit rigid substrate (23) connected in sequence; the digital signal transmission circuit rigid substrate (21) is arranged with an MCU module (211), a light source driving module (212), and a communication module (213); the analog signal transmission circuit rigid substrate (23) is arranged with a self-zeroing transimpedance amplifier (231), a band-pass filter (232), a battery (233), and a power management module (234); The MCU module (211) is used for sending control instructions, driving the non-spectroscopic infrared gas sensor (3) to work through the light source driving module (212), receiving analog signals sent by the self-zeroing transimpedance amplifier (231) and the band-pass filter (232), performing analog / digital conversion, calculating the amplitude of the signals, and transmitting the amplitude to the communication module (213); the non-spectroscopic infrared gas sensor (3) is used for detecting target gases in the gastrointestinal environment and outputting a small-amplitude current signal of the reaction gas concentration, and is connected with the self-zeroing transimpedance amplifier (231) and the band-pass filter (232); the self-zeroing transimpedance amplifier (231) and the band-pass filter (232) are used for converting the small-amplitude current signal into a large-amplitude voltage signal; and the communication module (213) is used for transmitting the amplitude of the signals calculated by the MCU module (211) to the extracorporeal receiving end in a wireless communication manner; The non-spectroscopic infrared gas sensor (3) comprises an infrared light source (31), a detection gas chamber (32), and an infrared detector (33); the infrared light source (31) is connected with the digital signal transmission circuit rigid substrate (21), and the infrared detector (33) is connected with the analog signal transmission circuit rigid substrate (23); and the infrared light source (31) is used for being driven by the MCU module (211) to radiate infrared light into the detection gas chamber (32), the target gas in the detection gas chamber (32) is absorbed after interacting with the infrared light, and is irradiated on the infrared detector (33); the infrared detector (33) receives the infrared light signal and converts it into a small-amplitude current signal of the reaction target gas concentration; The capsule detection circuit (2) is made of rigid-flex composite printed circuit board process, the flexible substrate (22) is arranged with a wire connecting the analog signal transmission circuit and the digital signal transmission circuit; the light source driving module (212) and the communication module (213) are electrically connected with the MCU module (211) on the digital signal transmission circuit rigid substrate (21) through copper foil wires, the self-zeroing trans-impedance amplifier (231) and the band-pass filter (232) are electrically connected on the analog signal transmission circuit rigid substrate (23) through copper foil wires, the band-pass filter (232) is electrically connected with the MCU module (211) through the flexible substrate (22), the battery (233) and the power management module (234) are electrically connected on the analog signal transmission circuit rigid substrate (23) through copper foil wires, and then the battery (233) and the power management module (234) are electrically connected with the MCU module (211), the light source driving module (212), the communication module (213), the self-zeroing trans-impedance amplifier (231) and the band-pass filter (232).

2. The ingestible sensor detection capsule of claim 1, wherein, The MCU module (211), the light source driving module (212) and the communication module (213) are configured with low power consumption to prolong the working time of the system.

3. The ingestible sensor detection capsule of claim 1, wherein, The capsule structure (1) comprises an analog signal transmission circuit chamber (11), a sensor chamber (13) and a digital signal transmission circuit chamber (12) connected in sequence; the sensor chamber (13) is provided with a grid for gas passing, the grid is coated with a waterproof and breathable film (14), which is a dimethylsiloxane film for blocking liquid and allowing gas to pass through; the digital signal transmission circuit rigid substrate (21) and the analog signal transmission circuit rigid substrate (23) are respectively distributed on the digital signal transmission circuit chamber (12) and the analog signal transmission circuit chamber (11); the infrared light source (31) and the infrared detector (33) are respectively distributed on the digital signal transmission circuit chamber (12) and the analog signal transmission circuit chamber (11).

4. The ingestible sensor detection capsule of claim 1, wherein, The in-vitro receiving end is provided with host computer application software (4), which is used for receiving and processing digital signals from the ingested sensor detection capsule and displaying in real time.

5. The ingestible sensor detection capsule of claim 1, wherein, The in-vitro receiving end comprises one or more of a smart phone and a personal computer. The in-vitro receiving end comprises one or more of a smart phone and a personal computer.

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