Tracheal tube device with rotating permanent magnet positioning and selective brain cooling function and temperature control method thereof

Abstract

The application discloses a tracheal catheter device with rotating permanent magnet positioning and selective brain cooling function and a temperature control method thereof, wherein a plurality of flexible semiconductor refrigerating sheets and a plurality of temperature and humidity sensors are inlaid on the inner wall side along the extension direction of the catheter and the side close to the outer wall of the flexible tracheal catheter; the function of heating the humidified gas entering the tracheal catheter is realized; the local low-temperature environment is realized by cooling the outer wall of the tracheal intubation tube, so that the brain is protected to a certain extent. The low temperature reduces the metabolic rate of brain cells and reduces the oxygen consumption of the brain, which helps to reduce brain injury and improve the brain function recovery effect of the patient; the flexible semiconductor refrigerating sheet and the temperature and humidity sensor are used for accurate temperature control, the temperature of the outer wall of the tracheal intubation tube is accurately adjusted, and the adverse effect of excessive temperature fluctuation on the brain protection effect is avoided, so that the method is more targeted and controllable than the traditional cooling method.

Description

Technical Field

[0001] This invention relates to medical devices, specifically to a tracheal tube device with rotating permanent magnet positioning and selective brain cooling functions, and its temperature control method. Background Technology

[0002] Nasal endotracheal intubation is one of the methods for establishing an artificial airway. Nasal endotracheal intubation has the advantages of simple operation, easy fixation, convenient oral care, good tolerance, and long tube retention time. It is now widely used in craniocerebral and oral surgery, trauma emergency care, comatose patients who need long-term ventilator oxygen supply, and patients with a lot of airway secretions. It is especially suitable for patients who have difficulty opening their mouths and cannot have a laryngoscope inserted.

[0003] Currently, nasotracheal intubation commonly uses the Endotrol method, where a movable guide wire is embedded in the inner wall of the endotracheal tube. The distal end of the guide wire is fixed to the distal end of the endotracheal tube, while the proximal end extends from the proximal end. Pulling on a metal ring causes the distal end of the endotracheal tube to tilt upwards, achieving nasotracheal intubation. However, this method still suffers from a low success rate, reportedly only 70%. Repeated intubation not only causes significant patient suffering but also, in cases where the endotracheal tube enters the esophagus in unconscious patients, often leads to oxygen deprivation and potential medical malpractice claims. Therefore, there is an urgent need for a method to effectively detect the current position of the endotracheal tube tip, providing timely alerts for incorrect positioning and allowing medical staff to identify and address any intubation complications such as misalignment during the intubation process.

[0004] Furthermore, the gas introduced into an artificial airway lacks the warming and humidification functions of a normal human body, causing significant discomfort to patients. Routine patients with severe pneumonia require warming and humidification of the delivered gas after endotracheal intubation to maintain a normal airway environment, similar to a normal airway, thus improving the weaning rate from invasive ventilation. After establishing an artificial airway with an endotracheal tube, the tube is connected to a ventilator equipped with a warming and humidification device. However, the operating room temperature is generally maintained within the range of 21-25℃, while the normal human respiratory tract temperature is generally within the range of 37.2-37.7℃, resulting in a significant temperature difference. The warmed and humidified gas, which is close to the body temperature, often cools down in the tube, producing condensation. This liquefies the water vapor that should have entered the lungs, reducing the humidification of the gas and causing negative effects such as silent dehydration of the lungs. Simultaneously, air cooled by the outdoor environment entering the lungs can cause dysfunction of the mucociliary system and affect sputum expectoration. Therefore, there is an urgent need for a way to effectively increase the temperature of the inner wall of the endotracheal tube to prevent condensation and temperature drop during gas transmission.

[0005] Currently, maintaining cerebral hypothermia is an effective treatment and protective method for patients with severe traumatic brain injury, stroke, or other serious traumatic brain injuries. Hypothermia reduces the metabolic rate by decreasing cellular glucose and oxygen consumption, thereby promoting neuroprotection and extending cell survival time. Selective brain cooling prevents the harmful effects of systemic hypothermia. Researchers have achieved selective brain cooling using a closed-loop circulation of cold water within a nasopharyngeal duct; however, this device still suffers from inaccurate temperature control of the circulating cold water and excessively large equipment size. Furthermore, current endotracheal intubation devices lack a cooling circulation system. Therefore, there is an urgent need for a method to cool and absorb heat from the outer wall of the endotracheal tube against the nasal cavity and pharynx during nasotracheal intubation, achieving selective brain cooling. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a tracheal tube device with rotating permanent magnet positioning and selective brain cooling functions, and its temperature control method, which achieves cooling of the outer wall of the tracheal tube while heating the airflow inside the tracheal tube through the inner wall of the tracheal tube.

[0007] This invention is achieved through the following technical solution:

[0008] A tracheal tube device with rotating permanent magnet positioning and selective brain cooling functions includes a tracheal tube, a temperature and humidity control system, and a rotating permanent magnet positioning system.

[0009] Several flexible semiconductor cooling chips are embedded at certain intervals along the extension direction of the flexible tracheal tube; the cold end of all the flexible semiconductor cooling chips is in contact with the outer wall of the tracheal tube, and the hot end of the flexible semiconductor cooling chips is in contact with the inner wall of the tracheal tube; several temperature and humidity sensors are arranged at intervals between the multiple flexible semiconductor cooling chips on the tracheal tube, and the humidity and temperature of the gas at different positions in the tracheal tube are obtained through each temperature and humidity sensor.

[0010] The temperature and humidity control system is used to dynamically adjust the voltage and current values ​​at both ends of each flexible semiconductor cooling chip. The temperature and humidity values ​​of the tracheal tube are obtained through each temperature and humidity sensor. Combined with the set target temperature threshold, PID control is used to dynamically adjust the voltage of each flexible semiconductor cooling chip to control the internal temperature of the tracheal tube to a fixed constant temperature.

[0011] The rotating permanent magnet positioning system includes an external magnetic field generator, an endotracheal tube assembly, and a control module. The external magnetic field generator includes a permanent magnet and a permanent magnet drive mechanism. The permanent magnet drive mechanism includes a three-axis drive mechanism and a robotic arm. The three-axis drive mechanism is mounted on the robotic arm and drives the permanent magnet to rotate and adjust the direction of the magnetic field. The endotracheal tube assembly includes a magnetic guide element and a magnetic sensor located at the distal end of the endotracheal tube. The magnetic guide element generates a guiding force under the action of an external magnetic field. The magnetic sensor is located adjacent to the magnetic guide element and is used to detect the intensity and direction of the external magnetic field and provide feedback signals.

[0012] The control module includes a signal processing unit and an execution unit. It is used to acquire analog signals from the magnetic sensor and control the motor of the permanent magnet three-axis drive mechanism through PWM signals, thereby adjusting the rotation angle of the permanent magnet. The software algorithm built into the control module adjusts the magnetic field in real time based on the feedback from the magnetic sensor. By adjusting the strength and direction of the external magnetic field in real time through the control module, the position and angle of the magnetic guiding element at the distal end of the endotracheal tube are precisely controlled to achieve accurate positioning of the tube.

[0013] Preferably, the temperature and humidity control system includes an MCU module, multiple temperature and humidity sensors connected to the MCU control module, a DC-DC converter connected to the MCU, and the MCU control module connected to the MOSFET after being isolated by an optocoupler. Each flexible semiconductor cooling chip is connected to a MOSFET and a DC-DC converter. Each MOSFET and DC-DC converter is individually controlled by the MCU control module. The output voltage is adjusted using the DC-DC converter, and the output current is adjusted using the power MOSFET through a PWM signal. After the temperature is set by the MCU control module, the voltage across the flexible semiconductor cooling chip in different areas is automatically adjusted to regulate the temperature and humidity.

[0014] Preferably, the MCU control module is connected to a current acquisition circuit and a voltage acquisition circuit. The current acquisition circuit and the voltage acquisition circuit monitor the actual current and voltage output to each flexible semiconductor cooling chip and feed them back to the MCU control module. The current acquisition circuit samples the INA180A2IDBVR current sensing amplifier, and the voltage acquisition circuit samples the output voltage using a voltage divider resistor.

[0015] Preferably, the MCU control module is also equipped with a display module. The MCU control module processes, filters, and calibrates the collected temperature and humidity data, and then uses a coordinate mapping algorithm to draw curves, mapping the collected temperature and humidity data onto the coordinate system of the display module. The MCU control module also processes the collected current and voltage data of each flexible semiconductor cooling chip, converting the analog voltage signal into a digital signal through its built-in ADC module, and converting the collected voltage and current data into coordinate values ​​through a preset algorithm to draw curves, which are then displayed on the display module.

[0016] Preferably, the MCU control module is connected to a storage device to store the collected voltage, current, and temperature and humidity data in the storage device; the temperature and humidity control system is also connected to an alarm module; the magnetic sensor is a Hall sensor or a magnetoresistive sensor; the temperature and humidity sensor is a thin-film digital sensor.

[0017] Preferably, the permanent magnet triaxial drive mechanism includes a permanent magnet, a permanent magnet drive motor mounted inside the inner ring, the permanent magnet drive motor mounted on the inner ring for driving the permanent magnet to rotate and change its magnetic field direction and angle, the inner ring drive motor connected to the inner ring for driving the inner ring to rotate relative to the outer ring, the inner ring position encoder for real-time monitoring of the rotation position and angle of the inner ring, the outer ring as the external support structure of the inner ring and internal components, the outer ring drive motor connected to the outer ring for driving the outer ring to rotate, the outer ring position encoder for monitoring the rotation position and angle of the outer ring, and the outer shell as the external protective structure of the entire triaxial drive mechanism.

[0018] On the other hand, the present invention provides a temperature control method for a tracheal tube device with rotating permanent magnet positioning and selective brain cooling function. The temperature and humidity control system uses PID control according to formula (1) to control the voltage of the semiconductor cooling chip.

[0019] u ( t )= K p e ( t )+ K i dτ + K d dtde ( t (1)

[0020] in: u ( t The output of the controller is the voltage across the flexible semiconductor refrigeration chip. e ( t )= Tset - Tactual( t (This is the set temperature) Tset Compared with the actual measured temperature Tactual ( t The error between ) K p It is proportional gain. K i It is integral gain. K d It is the differential gain;

[0021] To achieve adaptive adjustment of PID parameters, a neural network-optimized PID temperature controller is constructed by combining a feedforward neural network (MLP) with PID control. The feedforward MLP outputs the optimal PID gain in real time based on the current state characteristics. This enables the controller to self-adjust as the environment and target change; the temperature and physiological parameters of the gas at different positions in the tracheal tube (1) obtained by each temperature and humidity sensor (3) are used as the input of the feedforward neural network MLP, and the network output updates the parameters of the PID controller in real time. The PID controller calculates the voltage of the cooling chip based on this and drives the cooling chip to adjust the temperature, forming a closed-loop control.

[0022] Preferably, a two-layer feedforward neural network MLP is used as the PID parameter regulator, and the activation function is the linear rectified function ReLU. To enhance the nonlinear expressive power of the network while maintaining the stability of gradient propagation; the output layer has 3 nodes, each corresponding to a PID controller. , , With three gain parameters and linear activation in the output layer, the feedforward neural network MLP performs the function of processing the input vector. Nonlinear mapping:

[0023]

[0024] in, The input feature vector; For multiple points of temperature on the inner wall of the catheter, For multiple temperature points on the outer wall of the catheter, The patient's core body temperature, The temperature of the brain in the nasopharynx. The time that has been spent cooling down, Given the current cooling rate, Set a value for the target temperature or temperature difference;

[0025] Real-time computation function of neural networks Output the most suitable PID gain combination at the corresponding time. These outputs are directly used by the PID controller to change its parameters over time: This leads to adaptive PID control.

[0026] Preferably, during the training of the feedforward neural network MLP, the loss function Defined as the mean square value of temperature control error, for the setpoint of the outer wall temperature of the conduit. Formula (4) is used:

[0027]

[0028] in For the first The outer wall temperature is collected at a specific time or the average value of multiple points is taken.

[0029] If the inner wall temperature error is also considered, the inner wall temperature deviation term is added to the loss function with weights, and the overall loss function is then considered. By selecting weights While ensuring the accuracy of external wall temperature control, it limits the deviation of internal wall temperature from normal body temperature.

[0030] The present invention has the following beneficial effects:

[0031] This invention achieves the function of heating the humid gas entering the tracheal tube by embedding a number of flexible semiconductor cooling chips and a number of temperature and humidity sensors at certain intervals along the extension direction of the flexible tracheal tube; the cold end of the flexible semiconductor cooling chip is in contact with the outer wall of the tracheal tube, and the hot end of the flexible semiconductor cooling chip is in contact with the inner wall of the tracheal tube.

[0032] By cooling the outer wall of the endotracheal tube, a localized low-temperature environment is created, thus providing some protection for the brain. Low temperatures reduce the metabolic rate of brain cells and decrease oxygen consumption in the brain. In situations leading to cerebral ischemia and hypoxia, such as cardiopulmonary resuscitation, certain brain surgeries, or severe trauma, this helps reduce brain damage and improve the patient's brain function recovery. Utilizing flexible semiconductor cooling pads and temperature and humidity sensors for precise temperature control, the temperature of the endotracheal tube's outer wall is accurately regulated and stabilized between 17°C and 21°C. This avoids excessive temperature fluctuations that could adversely affect brain protection, making it more targeted and controllable than traditional cooling methods (such as whole-body cooling or the use of ice packs).

[0033] Maintaining the temperature of the endotracheal tube wall at 37.5°C, the same as the average temperature of the lungs, avoids irritation to the respiratory tract caused by inhaling cold air and prevents adverse reactions such as airway spasm and coughing. This can improve patient comfort and reduce respiratory complications for patients requiring prolonged mechanical ventilation, such as those in the intensive care unit (ICU) or undergoing prolonged anesthesia. Maintaining a stable temperature of the endotracheal tube wall helps maintain normal respiratory physiological functions, including mucociliary clearance and the integrity of the respiratory mucosa, thus helping to prevent thickened sputum and respiratory infections.

[0034] The temperature of the inner and outer walls of the endotracheal tube can be flexibly adjusted according to the needs of different patients and different clinical conditions. This personalized temperature control offers high flexibility in clinical applications and improves the targeted nature of treatment. Based on real-time monitoring data, medical staff can optimize treatment plans according to actual conditions and adjust temperature control strategies according to the patient's physiological state and environmental conditions, which helps to improve the quality and safety of treatment.

[0035] By embedding a magnetic element at the tip of a flexible endotracheal tube, the position of the tube tip can be precisely sensed externally using a magnetic field sensor or detector. The tube tip's location within the trachea can be accurately determined in three-dimensional space, with millimeter-level precision. This is crucial for ensuring the tube is in the optimal position, avoiding insertion too deeply or too superficially into the trachea, and preventing accidental insertion into the bronchi or outside the trachea. In complex airway anatomy, especially in patients with airway malformations or anatomical variations, traditional positioning methods are insufficiently accurate, while magnetic positioning provides more precise location information, reducing the risk of poor ventilation, atelectasis, or other complications due to inaccurate positioning.

[0036] By integrating the temperature regulation functions of the inner and outer walls of the endotracheal tube into the same device, it simultaneously achieves hypothermic brain protection and respiratory tract protection, realizing multiple therapeutic objectives in one medical device and breaking through the limitations of the past that only focused on airway ventilation.

[0037] Integrating a flexible semiconductor cooling chip and a temperature and humidity sensor into the design of the endotracheal tube creates a relatively independent temperature control system, reducing reliance on complex external equipment and simplifying operation. Electronic control technology enables precise temperature control and real-time monitoring, providing new insights into the intelligent and refined development of medical devices.

[0038] Utilizing advanced control algorithms (such as PID control) and a real-time monitoring and feedback mechanism, precise temperature control is ensured. After the temperature is set, the voltage across the semiconductor sensors in different areas is automatically adjusted to achieve accurate and stable temperature regulation. This provides more precise conditions for clinical treatment. The measured temperature and humidity of the inner and outer walls of the endotracheal tube are exported, and temperature change curves are plotted, facilitating postoperative care. This is a significant innovation in clinical temperature control. The temperature and humidity sensors can monitor the temperature and humidity of the inner and outer walls of the endotracheal tube in real time. Through the feedback system, the working state of the flexible semiconductor cooling chip can be adjusted in a timely manner, forming a closed-loop control to ensure that the temperature is always maintained within the set range, improving the reliability and stability of the system.

[0039] A novel treatment concept combining hypothermic brain protection and respiratory protection is proposed, unifying previously independent treatment measures (brain protection and respiratory management) through a temperature regulation system for endotracheal intubation. This brings new methods and means to clinical treatment and will broaden the treatment ideas and approaches of clinicians.

[0040] This approach is applicable to a wider range of clinical scenarios, not limited to traditional cardiopulmonary resuscitation and neurosurgery where brain protection is required. It provides better treatment conditions for patients with diseases that cause brain injury (such as severe septic shock, cardiac arrest, etc.) or those requiring long-term mechanical ventilation, and has broader clinical application prospects.

[0041] This invention provides a rotary permanent magnet positioning system for tracking and locating the trachea. A rotating magnetic field generated by an external magnetic field generator interacts with a magnetic sensor on the tracheal tube, enabling precise control and positioning of the tube. The positioning and display module can display the tube's position and orientation information in real time, helping doctors accurately insert the tube into the target location and avoiding accidental insertion into the esophagus or other non-target areas.

[0042] The positioning and display module displays the catheter's position and orientation information in an intuitive way (such as numbers and graphics), enabling doctors to quickly understand the catheter's status and make corresponding adjustments. The rotating permanent magnet positioning system is relatively easy to operate; doctors can master its operation after simple training, which helps to shorten surgical time and improve surgical efficiency.

[0043] Compared to traditional X-ray imaging positioning methods, the rotating permanent magnet positioning system eliminates the need for a radiation source, reducing radiation risks to patients and medical staff. The system utilizes high-performance permanent magnet materials and advanced control technology, ensuring its safety and reliability and minimizing surgical risks.

[0044] With its unique structural design and functional characteristics, the rotating permanent magnet positioning system has many beneficial effects in the medical field, such as improving the accuracy and safety of intubation, being easy to operate, being highly adaptable, reducing radiation risks, and promoting the development of medical technology, thus bringing patients a better medical experience and treatment results.

[0045] This invention utilizes a neural network-optimized PID temperature control algorithm to achieve precise control of the endotracheal tube temperature and effective selective cooling of the brain, overcoming the shortcomings of existing technologies in efficient and controllable whole-body cooling. It possesses significant innovation and clinical practical value. The design concept of this control system also provides a new approach to intelligent temperature control in medical devices, combining artificial intelligence algorithms with traditional controllers to adapt to the complex human body environment, thereby further improving the safety and effectiveness of treatment. Attached Figure Description

[0046] Figure 1 A schematic diagram of a tracheal tube device with rotating permanent magnet positioning and selective brain cooling function;

[0047] Figure 2 This is a block diagram of the temperature and humidity control system.

[0048] Figure 3 This is a schematic diagram of the PID control principle in this invention;

[0049] Figure 4 The temperature curve displayed by the display module;

[0050] Figure 5 This is a diagram illustrating the use of an endotracheal tube.

[0051] Figure 6 This is a schematic diagram of the permanent magnet drive mechanism in an external magnetic field generator.

[0052] Figure 7 A magnetic field distribution diagram for a permanent magnet;

[0053] Figure 8 This is a flowchart of the feedforward neural network training process of the present invention;

[0054] Figure 9 Schematic diagram of the feedforward neural network control structure:

[0055] Figure 10 Structure diagram of the neural network PID parameter optimization module;

[0056] Figure 11 Schematic diagram of the preparation process of the endotracheal tube of the present invention;

[0057] In the diagram: 1-tracheal tube, 2-flexible semiconductor cooling chip, 3-temperature and humidity sensor, 4-magnetic sensor, 5-magnetic guiding element, 6-permanent magnet, 7-permanent magnet triaxial drive mechanism, 8-permanent magnet drive motor, 9-inner ring, 10-inner ring drive motor, 11-inner ring position encoder, 12-outer ring, 13-outer ring drive motor, 14-outer ring position encoder, 15-outer shell. Detailed Implementation

[0058] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0059] like Figure 1 As shown, the overall structure of the tracheal tube device with rotating permanent magnet positioning and selective brain cooling function of the present invention includes a tracheal tube 1, a temperature and humidity control system and a rotating permanent magnet positioning system.

[0060] Several flexible semiconductor cooling pads 2 are embedded at regular intervals along the extension direction of the flexible endotracheal tube 1. The cold ends of all the flexible semiconductor cooling pads 2 are in contact with the outer wall of the endotracheal tube to reduce the temperature of the pharynx and achieve hypothermic brain protection. The hot ends of the flexible semiconductor cooling pads 2 are in contact with the inner wall of the endotracheal tube 1 to heat the humidified gas entering the endotracheal tube. At the same time, several temperature and humidity sensors 3 are arranged at intervals between the flexible semiconductor cooling pads 2 on the endotracheal tube 1. The temperature and humidity sensors 3 dynamically monitor the gas humidity and temperature at different locations of the endotracheal tube 1 to achieve secondary protection for the patient.

[0061] The flexible endotracheal tube of this invention is soft and flexible, adapting to the anatomical structure of the human airway, and plays an important role in medical procedures such as anesthesia, emergency care, and respiratory support. The tube body is made of medical-grade polymer material. Some flexible endotracheal tubes have an inflatable cuff located at the front end of the tube. When inflated, the cuff seals the gap between the trachea and the tube, preventing gas leakage and aspiration. The cuff material is highly elastic rubber or silicone, capable of withstanding a certain air pressure, and is not easily deformed or ruptured during prolonged use. The cuff includes a high-pressure, low-volume cuff and a low-pressure, high-volume cuff. The low-pressure, high-volume cuff exerts relatively less pressure on the tracheal mucosa, reducing the risk of mucosal damage. One end of the tube is typically connected to the tubing of an anesthesia machine or ventilator. This connector uses a standard Luer connector or other international standard connectors to ensure a tight and reliable connection with the respiratory equipment. During general anesthesia, the flexible endotracheal tube is used to establish an artificial airway, ensuring the patient's ventilation and oxygenation. The anesthesiologist selects an appropriate endotracheal tube based on the patient's airway condition, inserts it into the trachea, and then uses an anesthesia machine to provide positive pressure ventilation, thus providing safe respiratory support for the surgery.

[0062] The flexible semiconductor refrigeration chip used in this invention is a novel refrigeration device based on semiconductor materials. While possessing the refrigeration principle of traditional semiconductor refrigeration chips, it also exhibits flexibility and bendability, adapting to various complex surface shapes and special application scenarios, and conforming to various curved and irregularly shaped object surfaces. Like traditional semiconductor refrigeration chips, the flexible semiconductor refrigeration chip operates based on the Peltier effect. When direct current passes through a thermocouple composed of N-type and P-type semiconductors, energy transfer occurs at the junction of the two semiconductors. On one side of the junction, electrons transition from a lower energy level to a higher energy level, absorbing heat and lowering the temperature on that side, achieving a cooling effect; on the other side, electrons transition from a higher energy level to a lower energy level, releasing heat and raising the temperature on that side. By adjusting the direction and magnitude of the current, the cooling and heating effects can be controlled.

[0063] The temperature and humidity sensor used in this invention is a thin-film digital sensor, which has good linearity and stability. It adopts a digital output method and can be directly connected to digital devices such as microcontrollers. It directly contacts the object being measured and measures temperature and humidity through thermal or moisture conduction. Temperature and humidity sensors are evenly distributed on the inner and outer walls of the gas duct to detect the internal and external temperatures of the gas duct, providing detection data for overall temperature regulation.

[0064] like Figure 2 As shown, in order to achieve uniform temperature control inside the tracheal tube, a temperature and humidity control system is provided. This system dynamically adjusts the voltage and current values ​​across each flexible semiconductor cooling chip 2. After obtaining the temperature and humidity values ​​of the tracheal tube 1 through each temperature and humidity sensor 3, and combining them with the set target temperature threshold, PID control is used to dynamically adjust the voltage of each flexible semiconductor cooling chip 2 to control the temperature inside the tracheal tube to a fixed constant temperature, while ensuring that the temperature outside the tube is not too cold.

[0065] like Figure 3 As shown, the controller uses PID control according to formula (1) to control the voltage of the semiconductor cooling chip, so as to achieve the purpose of temperature control.

[0066] u ( t )= K p e ( t )+ K i dτ + K d dtde ( t (1)

[0067] in: u (t The output of the controller is the voltage across the flexible semiconductor refrigeration chip. e ( t )= Tset - Tactual ( t (This is the set temperature) Tset Compared with the actual measured temperature Tactual ( t The error between ) K p The proportional gain determines the strength of the controller's response to the current error. K i It is the integral gain, used to eliminate steady-state error. K d It is the differential gain, used to predict the trend of error changes and make adjustments in advance.

[0068] Temperature is measured using a temperature and humidity sensor positioned near the flexible semiconductor cooling chip. T 1 and T 2. The PID controller receives signals from the temperature and humidity sensor and calculates the temperature difference Δ. T = T 1− T 2 (or the difference between the set temperature and the set temperature), and then calculate the PID algorithm according to formula (1). u ( t That is, control voltage Vcontrol The flexible semiconductor cooling chip operates according to the received control voltage. Vcontrol It performs cooling or heating operations to regulate the temperature. After the flexible semiconductor cooling chip is in operation, the temperature and humidity sensor measures the temperature again and feeds the new temperature data back to the PID controller, forming a closed-loop control that continuously adjusts the voltage until the desired temperature difference or set temperature is reached.

[0069] To achieve adaptive adjustment of PID parameters, this invention introduces a multilayer perceptron (MLP) neural network combined with PID control to form a neural network-optimized PID temperature controller. The MLP outputs the optimal PID gain in real time based on the current state characteristics. This enables the controller to self-adjust as the environment and objectives change.

[0070] like Figure 9 As shown, the feedforward neural network control structure is as follows: the multi-point temperature and physiological parameters collected by the sensor are used as the neural network input, and the network output updates the parameters of the PID controller in real time. The PID controller calculates the voltage of the cooling chip based on this and drives the cooling chip to adjust the temperature, thus forming a closed-loop control.

[0071] Input Feature Design: The input layer of the feedforward neural network (MLP) simultaneously receives multiple sensor information and control state variables to comprehensively characterize the current temperature control requirements. In this embodiment, the input features include: multi-point temperature of the inner wall of the conduit. (e.g., readings from three sensors evenly distributed along the inner wall of the catheter), and multiple temperature readings on the outer wall of the catheter. The patient's core body temperature (such as bladder temperature) Nasopharyngeal brain temperature (as an indicator of brain temperature) (Time already spent cooling down) Current cooling rate (e.g., the rate of decrease in brain temperature per unit time) and the target temperature or temperature difference setpoint. These characteristics reflect the temperature distribution at different locations along the catheter, the patient's overall and brain temperature status, the stage of the cooling process (initial rapid cooling or maintenance phase), and the expected temperature control target. The feedforward neural network (MLP) uses this comprehensive information to determine how the current control strategy should be adjusted.

[0072] Network structure and output: such as Figure 10 As shown, a two-layer feedforward neural network is used as the PID parameter regulator. The number of nodes in the input layer corresponds to the aforementioned feature dimensions, with a total of no less than a dozen nodes. One to two hidden layers are set, each containing an appropriate number of neurons (e.g., 10-20 neurons per layer), and the activation function is the linear rectified function ReLU. This enhances the network's nonlinear expressive power while maintaining the stability of gradient propagation. The output layer has three nodes, each corresponding to a PID controller. , , With three gain parameters, the output layer uses linear activation (because the gain parameters are continuous real numbers). The function implemented by the feedforward neural network MLP can be represented as processing the input vector... Nonlinear mapping:

[0073]

[0074] in The input feature vector is used as the basis for the real-time computation function of the neural network. Output the most suitable PID gain combination at the corresponding time. These outputs are directly used by the PID controller to change its parameters over time: This leads to adaptive PID control. The control law of the controller can then be expressed as:

[0075]

[0076] Similar to formula (1), but the PID gain is no longer fixed, but is dynamically given by the feedforward neural network MLP based on the state. The instantaneous value. In this way, when the system is at different temperature stages or faces different individual differences, the "strength" of the controller will be automatically adjusted, so as to provide sufficient control during the rapid cooling stage, and to converge smoothly when approaching the target to avoid overshoot, while taking into account the comprehensive control of the patient's core body temperature and local brain temperature.

[0077] Control strategy characteristics: The neural network-optimized PID controller combines the robustness of classical control with the self-learning capability of intelligent control. When the temperature of the outer wall of the duct deviates from the target or the temperature of the inner wall of the duct fluctuates abnormally, the network adjusts the PID gain in a timely manner based on multi-point sensor information to correct the temperature deviation. For example, if it is detected that a rapid drop in brain temperature may trigger systemic side effects, the network can reduce... Slowing down the rate of cooling; conversely, if the brain temperature decreases slowly within a safe range, it increases the rate of cooling. and Enhanced cooling capacity. Furthermore, multi-point temperature feedback enables the network to balance temperature distribution across different sections. When the temperature of the outer wall of a certain section of the duct is detected to be lower than other locations, the power output of the cooling element in that section can be selectively reduced. This is reflected in the parameters by increasing the PID gain in areas with large local errors, thus providing more aggressive compensation. In this way, the temperature at each sensing point tends to be consistent, resulting in a more uniform temperature distribution along the duct. In summary, the neural network-optimized PID structure gives the temperature control system a stronger adaptability to nonlinear and time-varying characteristics and superior control performance.

[0078] Training data sources and network training methods

[0079] like Figure 8 As shown, in order for the feedforward neural network MLP to correctly map temperature states to PID control parameters, it is necessary to train the network offline using a large amount of experimental and clinical data. The network training data of this invention mainly comes from temperature change records in simulation model experiments, animal experiments, and clinical trials. For example, in highly realistic human model experiments, pig animal experiments, and patient clinical trials, researchers collected data on the changes in ductal wall temperature, nasopharyngeal brain temperature, and core body temperature over time at different cooling stages. These data reflect the dynamic changes in temperature when using this invention for selective brain cooling: including the magnitude of the decrease in brain and whole-body temperature in the initial cooling stage, the time required to reach the target temperature, the temperature fluctuation range in the maintenance stage, and the rate of rewarming after cooling is stopped (see the statistical results in Tables 1 to 3).

[0080] The training samples for the feedforward neural network MLP can be constructed as follows: The state characteristics at each time step (sensor readings and temperature change rate, etc.) are taken as input, with the desired output being the optimal PID parameter adjustment for that time step. The "optimal PID parameters" can be obtained through various means, such as extracting them from records of empirically tuned PID controllers (parameters corresponding to when each indicator is optimally adjusted manually) or selecting the best PID parameter by scanning the temperature control effects of different PID parameters in simulation models. This allows for global optimization of the PID gain under different scenarios, constructing a dataset corresponding to the optimal PID parameters for training the feedforward neural network MLP.

[0081] During training, the loss function Defined as the mean square value of temperature control error, for example, it can be used for the set value of the outer wall temperature of the conduit. ,use:

[0082]

[0083] in For the first The outer wall temperature is collected at specific times (or the average of multiple points is taken). If it is necessary to consider the inner wall temperature error simultaneously, the inner wall temperature deviation term can be weighted and added to the loss function. For example, the comprehensive loss... By selecting weights While ensuring the accuracy of external wall temperature control, the deviation of internal wall temperature from normal body temperature is limited. The goal of network training is to minimize the aforementioned loss function, that is, to ensure that the PID parameters output by the neural network minimize the sum of squared temperature errors. Backpropagation (BP) and gradient descent-based optimization methods are used to update the network weights. Specifically, an adaptive learning rate optimization algorithm, such as the Adam optimizer, is selected for iterative training of the network, which can accelerate convergence and avoid getting trapped in local minima. For the training dataset, mini-batch gradient descent is used to divide the sample set into several batches (e.g., each batch contains 32 time-point samples), and batch training is performed to ensure stable updates. Simultaneously, the validation set error is monitored to prevent overfitting. If the training data is limited, particle swarm optimization can also be used to globally search for the optimal solution of the network weights, thereby improving the robustness of training to initial values. In actual training, the initial learning rate can be set, for example, to 0.001, and the number of training iterations depends on the convergence (usually between 5000 and 20000 iterations for algorithm convergence) to ensure that the loss decreases steadily. After thorough training, the neural network PID controller will exhibit good generalization ability in a wide range of temperature change scenarios, and can output reasonable PID parameter adjustment values ​​in both rapid cooling and constant temperature maintenance phases.

[0084] Dynamic control process and execution steps:

[0085] The neural network-optimized PID controller operates throughout the entire cooling intervention process, adjusting the output of the flexible semiconductor refrigeration chip in real time. Its dynamic control process can be divided into the following continuous cyclic steps:

[0086] Multi-point data acquisition: The MCU (Microcontroller Unit) control module acquires current catheter inner and outer wall temperature data from various temperature and humidity sensors at a set frequency, as well as the patient's core body temperature and brain temperature. It also records the current time and stage (e.g., the duration of cooling). This data constitutes a state feature vector. As mentioned above, including Information such as...

[0087] Neural network calculation: The latest feature vector Input the neural network parameter regulator. After forward computation, the network outputs the parameters of the PID controller corresponding to the current state. For example, when the temperature of the outer wall of the conduit is still higher than the target and it is in the initial stage of cooling, the network may output a large value. To accelerate cooling; if the brain temperature is close to the target or the internal wall temperature is too low, the network will reduce... Prevent overshoot.

[0088] PID control output: The MCU will update the output. Load the PID control algorithm module. The PID controller reads the set target temperature (or allowable temperature range) and calculates the current error. In many cases, the present invention can employ a method of controlling the temperature of the outer wall of the catheter, in which case... (Or based on the error of the temperature difference between the inside and outside of the conduit). Subsequently, the control signal is calculated using PID formula (3). —That is, the voltage value that needs to be applied across the cooling chip.

[0089] Drive actuator: Control signal The output from the MCU is applied to the corresponding flexible semiconductor cooling chip via a power drive circuit. Since this invention has multiple cooling chip zones, the MCU can perform the above control calculations separately for each zone. That is, each zone has its own temperature feedback and control output. This allows for independent adjustment of zones and overall coordinated control. For example, if the temperature of the outer wall of the middle section of the conduit is slightly higher than the target while the temperature at both ends has reached the target, the MCU can increase the voltage of the middle section cooling chip only, while keeping the voltage of other areas unchanged, in order to reduce temperature unevenness.

[0090] Feedback and Loop: Flexible semiconductor refrigeration chip receives voltage The cooling / heating power is then adjusted in real time to change the catheter temperature. Temperature and humidity sensors detect the new temperature value and feed it back to the controller. The system then enters the next control cycle, returning to step 1 and continuously looping. Typical control cycles are in the millisecond to second range, making temperature control nearly continuous and real-time. This closed-loop operation ensures that the temperature is consistently maintained stably near the target range. When the cooling treatment needs to end, the control system gradually reduces the voltage of the cooling pads according to a preset rewarming curve, gently raising the temperature of the catheter's outer wall to near body temperature, avoiding sudden cessation of cooling and resulting rebound overheating.

[0091] The above-described control process achieves an adaptive temperature control closed loop: it utilizes a neural network to quickly "sense" the current state and adjust the PID gain, thereby precisely applying control through the PID algorithm. The effect is that it maintains a smooth transition of catheter temperature under various dynamic conditions (such as initial cooling, maintenance, and rewarming), satisfying the requirement of selective brain cooling for low external wall temperatures while ensuring that the internal wall and patient core temperatures do not change drastically.

[0092] like Figure 2 As shown, a power module controls the current and voltage of the flexible semiconductor thermoelectric cooler 2, a DC-DC converter regulates the output voltage, and a power MOSFET regulates the output current via a PWM (Pulse Width Modulation) signal. The DC-DC converter is connected to the MCU, which is connected to the MOSFET via optocouplers. Multiple power module MOSFETs and multiple DC-DC converters are used, with each flexible semiconductor thermoelectric cooler 2 connected to one MOSFET and one DC-DC converter. Each MOSFET and DC-DC converter is individually controlled by the MCU control module. After the temperature is set by the MCU control module, the voltage across the flexible semiconductor thermoelectric cooler 2 in different areas is automatically adjusted, achieving precise and stable temperature regulation and providing more accurate conditions for clinical treatment.

[0093] The MCU control module collects data from each temperature and humidity sensor 3 sequentially according to a certain order. For multiple temperature and humidity sensors 3 connected to the MCU control module, the MCU control module first sends a data read command to the first temperature and humidity sensor, waits for the data to be received and processed, and then performs the same operation on the second temperature and humidity sensor, and so on, to periodically collect data from each temperature and humidity sensor. By using the timer function of the MCU control module, a fixed time interval is set to collect data from each sensor to ensure the periodicity and consistency of data collection, thereby realizing the acquisition of temperature and humidity parameters of each section inside the tracheal tube 1.

[0094] To achieve precise control of the flexible semiconductor cooling chip 2, a current acquisition circuit and a voltage acquisition circuit are used to monitor the actual current and voltage output to the flexible semiconductor cooling chip 2 and feed them back to the MCU control module to achieve closed-loop control. The current sampling uses an INA180A2IDBVR current sensing amplifier to acquire the output current, and a voltage divider resistor is used to sample the input (output) voltage.

[0095] The MCU control module is also equipped with a display module. After processing, filtering, and calibrating the acquired temperature and humidity data, the MCU control module uses a coordinate mapping algorithm to plot curves, mapping the acquired temperature and humidity data onto the coordinate system of the display module. The display module uses a liquid crystal display (LCD) or an organic light-emitting diode display (OLED). The acquisition, processing, and curve plotting of temperature and humidity data are implemented through programming, and the temperature and humidity curves are displayed on the OLED screen. The MCU control module also collects the current and voltage data from each flexible semiconductor cooling chip 2. Using its built-in ADC (analog-to-digital converter) module, it converts the analog voltage signals into digital signals, thus acquiring voltage and current data. A preset algorithm converts the acquired voltage and current data into coordinate values, plots curves, and displays the voltage and current curves on the OLED screen. The MCU control module is connected to a storage device to store the acquired voltage, current, and temperature and humidity data for later viewing and analysis.

[0096] like Figure 4The figures show the experimental results of multi-point temperature control according to this invention. The left-hand settings interface displays the inner wall temperature setpoint of 28.5℃ and the outer wall temperature setpoint of 20.5℃. In the six curves on the right, the blue curve represents the temperature of the three outer wall sensors, the red curve represents the temperature of the three inner wall sensors, and the black dashed line represents the target value. It can be seen that under intelligent control, the temperature at each measuring point steadily approaches its target temperature, and the temperature difference between the inner and outer walls remains within a safe range. This invention enables the multi-point temperatures of the outer and inner walls of the conduit to quickly converge to the target value and remain stable. The readings of the three outer wall sensors (blue curve) gradually decrease from an initial temperature of approximately 25℃, approaching the set level of 20℃ in about 60 seconds; the inner wall temperature (red curve) rises from approximately 30℃ and stabilizes at close to 29℃ (slightly lower than the set 30℃, used to simulate the 37℃ condition of the human body's inner wall). Throughout the process, the curves transition smoothly without significant oscillations or overshoot. This indicates that the neural network-optimized PID control effectively suppresses temperature overshoot and keeps the steady-state error within a very small range. It is noteworthy that the temperatures at different locations on the outer wall almost overlap, and the temperature differences at various points on the inner wall are also very small, proving that the temperature distribution along the duct wall is highly uniform. In contrast, if uniform and fixed PID parameters are used, temperature deviations may occur at certain locations, or undershoot / overshoot may occur when approaching the target. The present invention enables coordinated operation across all regions, quickly responding to local deviations, resulting in a balanced and stable temperature field distribution.

[0097] Further comparative experiments showed that the neural network PID controller outperformed the traditional PID controller in both dynamic response and steady-state accuracy. In the initial cooling phase, the network-optimized controller provided greater driving force than the fixed PID, increasing the rate of temperature decrease on the catheter outer wall by approximately 15%, thus reaching the required low-temperature range more quickly. However, as the temperature approached the target, the traditional PID often exhibited overshoot due to its fixed parameters (the catheter outer wall temperature briefly dropped below the target by, for example, 2°C or more, before rising again); conversely, the neural network adjusted its parameters promptly based on the error trend. and This ensures that the overshoot does not exceed 0.5℃ and the settling time is shortened. For example, under the same test conditions, the time required for the intelligent controller to stabilize the outer wall temperature within the target range (±0.2℃) is reduced by about 20%, and the steady-state error is negligible. The inner wall temperature of the conduit remains constant at close to 37℃, only slightly increasing in the initial stage of cooling before being controlled back to steady state, proving that the algorithm can meet the dual requirements of cooling the outer wall and maintaining a constant inner wall temperature.

[0098] More importantly, the improved temperature control precision led to significant improvements in clinical outcomes. In animal experiments, selective cooling using this invention for one hour resulted in an average decrease of approximately 4.1°C in the pig's brain temperature, while the core body temperature decreased by only about 0.9°C. Preliminary clinical trials showed that the average nasopharyngeal temperature decreased from 37.5°C to approximately 34.2°C, while the bladder temperature only decreased from 37.6°C to 35.8°C, demonstrating the selective cooling effect on the brain (brain temperature decreased by approximately 3.3°C, and the whole-body temperature decreased by approximately 1.8°C). Throughout the cooling process, due to stable temperature control, patients did not experience significant chills, and vital signs such as blood pressure and heart rate remained stable. During the rewarming phase, the control system slowly warmed the body at a rate of approximately 1°C per hour, successfully avoiding complications such as fever rebound or hypotension that could be caused by rapid rewarming. Furthermore, examination of the tracheal mucosa revealed no damage caused by localized hypothermia—this is closely related to the strict control of the duct wall temperature within a safe range and its uniform distribution without supercooled spots.

[0099] The above experimental results verify the effectiveness and safety of the temperature control system of this invention. Through PID control optimized by neural networks, not only is a faster and more stable temperature response achieved, but the efficacy and safety range of selective brain cooling are also ensured. The temperature curves clearly show that the brain cooling effect is significantly better than the whole-body cooling effect (more than doubled), which is of great significance for clinical scenarios requiring rapid reduction of brain temperature, such as brain protection after cardiopulmonary resuscitation and stroke emergency care. At the same time, the stable temperature control avoids the common side effects of traditional whole-body cooling, providing patients with a gentler treatment experience.

[0100] This invention combines a rotating permanent magnet for precise positioning with a neural network-optimized temperature control endotracheal tube device, achieving selective hypothermia protection for the patient's brain. The temperature control algorithm employs an innovative structure of feedforward neural network + PID control, which adaptively adjusts the cooling output based on real-time feedback, ensuring the temperature of the inner and outer walls of the tube remains within an ideal range. Compared to traditional fixed-parameter control methods, this intelligent control system significantly improves dynamic performance and steady-state accuracy: faster temperature response, smaller overshoot oscillations, and more uniform spatial distribution, ensuring effective cooling while minimizing disturbance to normal physiological functions.

[0101] Preliminary results from animal and clinical trials have confirmed its clinical value: by precisely controlling the hypothermia of the catheter's outer wall, this invention can significantly reduce brain temperature in a short time without causing serious systemic side effects, reducing the probability of brain injury occurrence and development; the constant temperature function of the inner wall ensures airway safety and patient comfort, avoiding tracheal mucosal damage or respiratory complications that may be caused by traditional cooling methods. This selective brain cooling technology holds promise for application in resuscitation after cardiac arrest, severe traumatic brain injury, stroke, and other emergency treatments requiring reduced brain metabolism, improving patients' neurological prognosis.

[0102] This invention employs a multi-point temperature control system to precisely regulate the temperature of the inner and outer surfaces of an endotracheal tube. The flexible endotracheal tube contains several flexible thermoelectric coolers and temperature and humidity sensors embedded along its length. Each flexible thermoelectric cooler (based on the Peltier effect) has one end close to the outer wall of the tube for localized cooling, and the other end close to the inner wall to heat the gas entering the airway. This creates a low-temperature environment on the outer wall of the tube to selectively lower brain temperature, while the inner wall is maintained at near-normal body temperature to protect the airway. Temperature and humidity sensors are distributed near each cooler, collecting temperature data from multiple points inside and outside the tube in real time. The control system, centered on a microcontroller (MCU), dynamically adjusts the voltage output of each flexible thermoelectric cooler based on the sensor data, including the temperatures inside and outside the tube, the patient's core body temperature, and the nasopharyngeal brain temperature. The goal is to maintain a constant temperature of approximately 37.5°C on the inner wall of the tube while stably controlling the outer wall within a safe range of 18–21°C, achieving precise localized cooling while avoiding overcooling or overheating.

[0103] Because patient body temperature and environmental conditions change dynamically during surgery, the temperature control system must have rapid response and adaptive capabilities. On the one hand, it is necessary to ensure a smooth and controllable cooling process to avoid cold damage to local tissues caused by excessively low catheter wall temperature; on the other hand, it is necessary to maintain a constant catheter wall temperature to prevent cold air stimulation or lowering of the overall body temperature. To this end, this invention designs a closed-loop feedback control architecture: sensors provide real-time temperature feedback, and the control algorithm calculates the optimal driving voltage of the cooling element based on the error between the set target temperature and the actual temperature, correcting the temperature deviation by adjusting the cooling / heating power of the cooling element. The basic control adopts a classic PID controller framework to achieve automatic temperature regulation. On this basis, a feedforward neural network is introduced to adaptively optimize and adjust the PID parameters, enabling the system to adaptively adjust the control strength according to different stages and environmental changes, thereby significantly improving the stability and accuracy of temperature control.

[0104] like Figure 2 As shown, the temperature and humidity control system is also connected to an alarm module. During the gas delivery process, the temperature and humidity sensor 3 dynamically monitors the system. If the temperature and humidity of the delivered gas do not meet the requirements and exceed the threshold preset by the MCU control module, or if the patient experiences abnormally high temperatures, the alarm module will issue a reminder to facilitate effective intraoperative care. The alarm module can be a buzzer, LED light, vibration motor, or audible and visual alarm. When the temperature exceeds the set threshold, the MCU control module controls the buzzer to sound an alarm, or the LED light acts as a visual alarm device, using different colors or flashing frequencies to alert medical staff. The vibration motor provides a reminder, or the audible and visual alarm emits a strong alarm signal; or the voice module plays a pre-recorded voice message for reminder.

[0105] The rotating permanent magnet positioning system includes an external magnetic field generator, an endotracheal tube assembly, and a control module. The external magnetic field generator includes a permanent magnet and a permanent magnet drive mechanism. The permanent magnet is preferably made of high-performance neodymium iron boron material (e.g., N52 grade), with a magnetic field strength range of 0–300 mT (millitales), more preferably 100–200 mT. The magnet rotation frequency is 0–5 Hz, enabling dynamic magnetic field adjustment. The magnetic field gradient generated by the permanent magnet in the near-field region can reach up to approximately 5 mT / mm, thus providing sufficient magnetic force for traction guidance. Figure 7 As shown,

[0106] The permanent magnet drive mechanism includes a three-axis permanent magnet drive mechanism and a robotic arm. The three-axis permanent magnet drive mechanism is mounted on the robotic arm and drives the permanent magnet to rotate and adjust the magnetic field direction. The drive motor of the three-axis drive mechanism is preferably a brushless DC motor, equipped with an encoder to achieve precise angle control. Its rated power is about 50 W, and its no-load speed can reach 3000 rpm. Except for the permanent magnet, other materials are made of non-magnetic materials (such as brass alloy or engineering plastics) to ensure that the magnet rotation process is not affected by magnetic interference and to ensure that the magnetic field direction adjustment accuracy is within 1°.

[0107] like Figure 6 As shown, the permanent magnet triaxial drive mechanism includes a permanent magnet 6, which is the core component for generating a magnetic field, forming a specific magnetic field through its own magnetic properties. A permanent magnet drive motor 8 is mounted on the inner ring 9 and connected to the permanent magnet 6, directly driving the permanent magnet to rotate and change its magnetic field direction and angle. The permanent magnet 6 and the permanent magnet drive motor 8 are installed inside the inner ring 9 and can rotate within a certain range, serving to support and initially adjust the angle of the permanent magnet. The inner ring drive motor 10 is connected to the inner ring 9 and is responsible for driving the inner ring to rotate relative to the outer ring 12, further adjusting the spatial angle of the permanent magnet and the entire inner ring. The inner ring position encoder 11 is used to monitor the rotational position and angle of the inner ring 9 in real time, providing feedback signals to the control system for precise control of the inner ring's rotation. The outer ring 12 serves as the external support structure for the inner ring 9 and its internal components, and can also rotate itself, providing additional adjustment dimensions. The outer ring drive motor 13 is connected to the outer ring 12 and drives the outer ring to rotate, allowing the entire inner ring and permanent magnet assembly to be adjusted over a wider range of spatial angles. The outer ring position encoder 14 is used to monitor the rotational position and angle of the outer ring 12 and feed it back to the control system to achieve precise control of the outer ring rotation. The housing 15 serves as the external protective structure for the entire three-axis drive mechanism, protecting internal components, preventing dust and interference, and providing a mounting base for internal parts.

[0108] After the permanent magnet drive motor 8 is powered on, it outputs torque according to the control command, driving the permanent magnet 6 to rotate around its own axis. By changing parameters such as the motor's speed and direction, the rotation angle and speed of the permanent magnet can be precisely controlled, thereby adjusting the direction and characteristics of the magnetic field it generates. The inner ring drive motor 10 receives commands from the control system and drives the inner ring 9 to rotate relative to the outer ring 12. During rotation, the inner ring position encoder 11 collects the position information of the inner ring in real time and feeds it back to the control system. The control system adjusts the operating state of the inner ring drive motor according to the deviation between the feedback information and the target angle, so that the inner ring can be precisely rotated to the specified angle, driving the permanent magnet to change the spatial angle in one dimension. The outer ring drive motor 13 works according to the commands of the control system, driving the outer ring 12 to rotate, thereby adjusting the angle of the inner ring and the permanent magnet assembly as a whole in space. The outer ring position encoder 14 continuously monitors the rotation angle of the outer ring and feeds the data back to the control system. The control system adjusts the outer ring drive motor in real time according to the difference between the feedback value and the preset value, ensuring that the outer ring rotates to the accurate position, realizing the spatial angle adjustment of the permanent magnet in another dimension.

[0109] By coordinating the rotation of the permanent magnet itself, the rotation of the inner ring, and the rotation of the outer ring, the spatial position and angle of the permanent magnet can be adjusted in all directions and with precision in three-dimensional space. This allows for flexible adjustment of the magnetic field direction, intensity distribution, and other characteristics to meet the specific magnetic field requirements of different application scenarios.

[0110] like Figure 1 As shown, the endotracheal tube assembly includes a magnetic guiding element 5 and a magnetic sensor 4 disposed at the distal end of the endotracheal tube 1. The magnetic guiding element is, for example, a small cylindrical permanent magnet (preferably neodymium iron boron), approximately 3 mm in diameter and 10-15 mm in length, fixed to the distal end of the tube, used to generate a guiding force under the influence of an external magnetic field. The magnetic sensor 4 is disposed adjacent to the magnetic guiding element, used to detect the strength and direction of the external magnetic field and provide a feedback signal. This magnetic sensor preferably employs a Hall effect magnetic field sensor (e.g., the Allegro A1324 linear Hall sensor), with an effective detection distance of up to 100 mm and a sensitivity of approximately 0.05 V / T (volts per Tesla); its output signal is amplified approximately 20 times by a preamplifier circuit to improve the measurement accuracy and signal-to-noise ratio of weak magnetic field signals. The magnetic sensor is mounted inside the tube by a support structure and encapsulated and fixed using medical-grade adhesive to ensure stable sensor position and waterproof safety during intubation.

[0111] The control module includes a signal processing unit and an execution unit, implementing closed-loop control with a microcontroller at its core. The microcontroller preferably uses a 32-bit ARM Cortex-M series microcontroller (such as the STM32 series), whose built-in analog-to-digital converter (ADC) is used to acquire analog signals from the magnetic sensor and control the motor of the permanent magnet three-axis drive mechanism via PWM signals, thereby adjusting the rotation angle of the permanent magnet. The software algorithm built into the control module adjusts the magnetic field in real time based on feedback from the magnetic sensor: the control algorithm can employ PID closed-loop control to accurately correct magnetic field deviations; and can combine fuzzy control or adaptive control strategies to dynamically adjust PID parameters to improve the system's adaptability to different patient anatomical differences; if necessary, a neural network control model can also be introduced, using the trained nonlinear model to improve control accuracy and robustness in complex environments. Through the above control module, the system can adjust the strength and direction of the external magnetic field in real time, precisely controlling the position and angle of the magnetic guiding element at the distal end of the endotracheal tube, thereby achieving precise positioning of the tube.

[0112] In the specific implementation process, the manufacturing and assembly steps of the rotating permanent magnet positioning system include:

[0113] (1) Assembly of the magnetic field generating device: Fix the permanent magnet to the permanent magnet three-axis drive mechanism, adjust the magnet installation so that its magnetic pole direction can be accurately changed according to the design when rotating, ensure the structure is firm and avoid mutual interference of magnetic components.

[0114] (2) Magnetic sensor calibration: After the magnetic sensor is assembled, zero-point calibration is performed under conditions without external magnetic field interference (the baseline value of the sensor output is recorded when there is no magnetic field). Then, the sensor output is measured under a known magnetic field strength to calculate the actual sensitivity (V / T) and adjust the amplifier gain accordingly. By establishing the correspondence between the sensor output and the magnetic induction intensity through multi-point calibration, the linearity and accuracy of the magnetic sensor measurement are ensured to meet the requirements.

[0115] (3) Catheter assembly fixation: The calibrated miniature magnetic sensor is fixed in the lumen of the distal end of the endotracheal tube, adjacent to the magnetic guiding element. A medical biocompatible adhesive is used to encapsulate and seal the sensor and its leads to prevent liquid intrusion or mechanical vibration during disinfection and intubation. The magnetic guiding element (a small permanent magnet) is embedded and fixed at a predetermined position at the distal end of the tube, positioning it relative to the magnetic sensor. This ensures that when subjected to an external magnetic field, the distal end of the tube can be deflected in the desired direction, thereby achieving magnetic navigation-assisted intubation.

[0116] like Figure 1 , Figure 4 and Figure 5 As shown, a control method for a rotating permanent magnet positioning system includes the following steps:

[0117] (1) Magnetic field model establishment and parameter calibration: A magnetic field model generated by the rotating permanent magnet is established to calculate the magnetic field strength and gradient at the distal end of the conduit. Based on the physical properties of the magnetic field, the external permanent magnet is approximated as a magnetic dipole, and its magnetic induction intensity at any point in space is... It can be calculated using formulas, for example, on the axis.

[0118]

[0119] in The permeability of free space, The magnitude of the magnetic moment. and These are the radius and length of the magnet, respectively. Let be the axial distance from the center of the magnet. Taking the partial derivative of the above magnetic field formula with respect to spatial coordinates yields the magnetic field gradient distribution. The magnetic field gradient in the axial direction decreases approximately inversely with increasing distance. Based on the magnetic field strength and gradient model, the magnetic force acting on the magnetic guiding element can be calculated. Approximately satisfies ,in The magnetic moment vector of the distal magnetic guiding element of the catheter. This represents the external magnetic field strength vector. Model parameters (such as the equivalent magnetic moment of the magnet) are obtained through experimental calibration, and the correspondence between magnetic sensor readings and the actual magnetic field is calibrated to ensure the control system's accurate and reliable sensing of the magnetic field strength.

[0120] (2) Intubation Path Planning: Before intubation, the optimal path of the endotracheal tube from the inlet to the target location in the trachea is planned. A third-order Bezier curve is used to fit and optimize the intubation path. This path is determined by the start point, the end point, and two control points. The parametric equation of the Bezier curve is:

[0121]

[0122] in This is the starting position of the catheter. Target location of the trachea and These are intermediate control points used to adjust the shape and curvature of the path. The selection of control points is optimized. , The location of the catheter allows for the generation of a smooth, continuous curved path that avoids anatomical obstacles, guiding the distal end of the catheter into the trachea along this path. Anatomical constraints (such as avoiding contact with the esophageal wall and vocal cords) are considered during trajectory planning to ensure the feasibility and safety of the resulting Bezier curve path in actual intubation.

[0123] (3) Closed-loop control execution: During cannulation, the external magnetic field is adjusted in a closed loop through the control module. Based on the planned path, the target orientation (i.e., the desired magnetic field direction) that the distal end of the catheter should reach at each stage is determined. The magnetic sensor detects the current magnetic field strength and direction at the distal end of the catheter in real time, and compares it with the desired value to obtain the error. The control module uses a PID algorithm to dynamically adjust the rotation angle of the magnet based on the error, and its control output satisfies:

[0124]

[0125] in , , These are the proportional, integral, and derivative coefficients of the PID controller. By appropriately tuning these parameters, the magnetic field deviation can be corrected quickly and stably. To improve the robustness of the control, a fuzzy control strategy can be introduced on the basis of PID control, adaptively adjusting the PID parameters according to the magnitude and rate of change of the error. When model uncertainties or external disturbances exist, an adaptive control algorithm is used to correct the control parameters online. In addition, a control model based on a neural network can be combined to predict and correct the magnetic field control quantity using the nonlinear mapping relationship obtained through training, thereby improving the accuracy of catheter positioning control in complex environments. Through the above closed-loop control, it is ensured that the magnetic guiding element at the distal end of the catheter can be strictly advanced and positioned along the planned path.

[0126] (4) Intubation guidance and positioning: In actual intubation, the operator gradually inserts the endotracheal tube into the patient's airway along the planned path. The control module synchronously drives the external permanent magnet to rotate to generate a guiding magnetic field. As the distal end of the tube enters the pharynx and glottis region, the control system continuously corrects the direction of the magnetic field based on feedback from the magnetic sensor, guiding the distal end of the tube toward the tracheal inlet. The tube advances along the predetermined Bezier curve path. When the magnetic sensor detects that the distal end of the tube has reached the target position (e.g., the magnetic field strength reaches a preset threshold or the positioning error converges to an allowable range), the control module stabilizes the magnetic field to maintain the tube position. Subsequently, the external magnetic field generator is removed, and the endotracheal tube is fixed in the predetermined position within the patient's airway, completing the intubation positioning. Through the above control method, precise control of the endotracheal tube insertion path and posture can be achieved, improving the success rate and safety of endotracheal intubation operations, such as... Figure 5 As shown.

[0127] like Figure 11 As shown, the process of fabricating a flexible semiconductor refrigeration chip on a flexible endotracheal tube is as follows:

[0128] S1. Substrate Preparation and Cleaning: A flexible endotracheal tube is selected as the substrate. The tube is made of medical-grade durable flexible material, such as silicone or polyurethane, with a diameter of 5-10 mm. Dust, grease, and other impurities on the tube surface are removed: First, rinse with a neutral detergent and deionized water, then place it in an ultrasonic cleaning tank and clean with ethanol and deionized water for 5-10 minutes respectively to remove surface-adhered organic matter and particles. The liquid temperature is controlled at 25-40℃ during the cleaning process to improve the cleaning effect. After cleaning, the inner and outer surfaces of the tube are dried with pure nitrogen gas, and the tube is placed in a clean oven at 50℃ for 10-30 minutes to ensure the tube surface is dry, clean, and free of residue, providing a clean substrate surface for subsequent processes.

[0129] S2, Surface Activation Pretreatment: The surface of the conduit after cleaning and drying in step S1 is activated to improve film adhesion and uniformity. Plasma surface treatment is preferred, for example, introducing oxygen into a vacuum plasma cleaner, maintaining a pressure ≤100 Pa, applying a radio frequency power of 50–200 W, and plasma treatment for 1–5 minutes to create microscopic roughening of the conduit surface and increase surface energy. This step removes residual organic matter from the conduit surface and introduces polar functional groups, thereby enhancing the adhesion of subsequent deposited layers. Optionally or additionally, immediately after plasma treatment, a silane coupling agent primer (e.g., 3-aminopropyltriethoxysilane APTES alcohol solution, concentration 1%–5%) is coated onto the conduit surface, allowed to stand for 5–10 minutes to allow self-assembly into a film, and then baked at 100°C for 10 minutes to cure the coupling agent. After the above activation pretreatment, the conduit surface has good wettability and activity, ensuring that the film layers are firmly bonded and uniformly distributed in the subsequent coating process.

[0130] S3, Deposition of the bottom electrode layer: A flexible bottom electrode conductive layer is deposited on the outer surface of the pretreated inner wall of the conduit, serving as the lower electrode of the semiconductor cooling chip. Magnetron sputtering is preferably used to deposit the metal thin film: the conduit is fixed on a rotatable base to ensure uniform deposition, and placed in a vacuum sputtering chamber where the substrate vacuum level is evacuated to no higher than 5 × 10⁻⁴ Pa. Two metal layers are used to improve adhesion and conductivity: first, an adhesion layer metal such as titanium (Ti) or chromium (Cr) is sputtered, with a thickness of approximately 10–100 nm, a sputtering power of, for example, 50 W, an argon working pressure of approximately 0.5 Pa, and a deposition rate of approximately 0.1 nm / s; subsequently, a main conductive metal layer, such as gold (Au) or copper (Cu), is sputtered on top of this layer. When Au is selected, the sputtering power is, for example, 100–200 W, the argon pressure is 0.5–1 Pa, the deposition rate is approximately 1–5 nm / s, and the deposition thickness is preferably in the range of 1–5 μm. When Cu is selected, a thin layer of Au (e.g., 0.1–0.5 μm thick) can be sputtered after the Cu layer is sputtered to a thickness of approximately 1–3 μm for oxidation protection. During the deposition process, the film thickness is monitored in real time using a quartz crystal monitor, and deposition is stopped when the predetermined thickness is reached. The bottom electrode metal layer should be uniform, continuous, and firmly adhered, without peeling or cracking. If necessary, the deposited conduit can be placed in an inert atmosphere (such as nitrogen) and heat-treated at 80–120 °C for 30–60 minutes to release the internal stress of the film and improve the adhesion and stability of the metal film.

[0131] S4, Bottom Electrode Patterning: The continuous metal bottom electrode layer obtained in step S3 is processed into the desired pattern to form electrically isolated electrode regions, providing corresponding bottom electrodes for subsequent deposition of N-type and P-type semiconductors. This step can be achieved using a photoresist mask combined with wet etching or laser scribing. A preferred method is as follows: A layer of photoresist (e.g., a negative photoresist with a thickness of 10–20 μm) is uniformly coated onto the surface of the conduit metal layer. A flexible film-mounting fixture is used to ensure uniform coverage. Then, a special fixture is used to rotate the conduit and expose the pre-designed patterned regions (including at least two separate electrode regions). After development, selective etching is performed on the metal regions not protected by the photoresist using an appropriate etchant. For example, potassium iodide solution can be used for the Au layer, and ferric chloride solution can be used for the Cu layer. The etching temperature is maintained at 25–40°C, and the etching time is controlled at 1–5 minutes until the conduit substrate is exposed, forming the desired electrode pattern. The size of each electrode region depends on the design of the cooling chip, typically a rectangular or annular region, with a spacing of, for example, 0.5–1 mm to ensure insulating separation of the electrodes. After etching, the conduit is thoroughly rinsed with deionized water to remove corrosion byproducts, and then rinsed with anhydrous ethanol to avoid moisture residue. It is then blown dry and heated to 50–60°C for 5 minutes. Finally, the photoresist mask is removed (using acetone for ultrasonic cleaning for 2–5 minutes) to obtain mutually insulated metal bottom electrode regions (referred to as the first and second electrode regions), whose surfaces are clean and free of residue.

[0132] S5, N-type semiconductor deposition mask setup: Before depositing N-type thermoelectric material on the conduit, a mask is used to shield the undeposited areas to ensure that the N-type material is deposited only on the designated electrode area. A customized flexible metal mask is tightly attached to the conduit surface, covering the second electrode area and its surrounding area, exposing only the deposition window corresponding to the first electrode area. The mask should be securely fixed and accurately positioned, aligned with the first electrode area and slightly larger than the electrode area to ensure complete electrode coverage. Preferably, the mask is tightly fitted to the substrate surface to prevent material leakage under the mask during deposition. For cylindrical conduits, a semi-circular opening mask can be used and locked with a mechanical clamp to achieve a surrounding shielding of the target electrode area. After the mask setup is complete, check that the unshielded area contains only the target electrode and no other exposed parts before proceeding with the deposition process.

[0133] S6, Depositing the N-type semiconductor thermoelectric material layer: Deposit an N-type semiconductor thermoelectric material thin film in the first electrode region exposed by the mask. Preferably, a Bi2Te3-based alloy thin film is deposited as the N-type thermoelectric material using magnetron sputtering. The conduit is mounted on a rotatable fixture within the sputtering equipment, the mask is adjusted and kept fixed, and a vacuum is evacuated to a substrate vacuum level not exceeding 1 × 10⁻³ Pa. A high-purity N-type Bi2Te3 target (with appropriate Se doping to improve N-type conductivity) is selected, and high-purity argon gas is introduced to a working pressure of 0.2–0.5 Pa. Deposition is performed using RF sputtering mode at a power of 100–300 W. To improve the film crystallinity, the substrate temperature is controlled at 50–100 °C during sputtering (at which the conduit material can withstand the temperature without deformation). The deposition time is determined based on the target thickness; calculated at a deposition rate of approximately 0.5–2 nm / s, the time required to achieve, for example, a 5 μm thickness is approximately 0.7–2.8 hours. The preferred deposition thickness is 5–15 μm to balance device flexibility and cooling performance. If the full thickness cannot be deposited in one step, multi-stage deposition can be used, with each stage depositing 1–2 μm, followed by pausing the cooling of the conduit to room temperature before continuing to the next stage, until the total required thickness is reached. During deposition, the thickness growth is monitored using a crystal oscillator or a monitoring chip placed near the conduit to ensure that the thickness is within the specified range and the composition is close to the stoichiometry. After deposition, the sample can be annealed in a vacuum or nitrogen atmosphere at 100–150 °C for 30–60 minutes (the upper limit is selected according to the temperature tolerance of the conduit material) to promote Bi2Te3 film crystallization and improve its thermoelectric properties. After annealing, the film should be slowly cooled to room temperature to avoid film cracking due to thermal shock. The resulting N-type semiconductor film should be uniform and dense, with a thickness of approximately 5 μm (allowable range 5 ± 1 μm or according to design requirements), well bonded to the bottom first region electrode, and completely covered without defects.

[0134] S7, Removing the N-type Deposition Mask: After N-type semiconductor material deposition and cooling, carefully remove the mask used in step S5 from the guide tube surface. Release the mechanical clamps and remove the metal mask, avoiding applying shear stress to the newly deposited N-type film. If a small amount of deposited material debris adheres to the back of the mask, gently clean the guide tube surface with a soft brush or lint-free cloth to ensure the second electrode area remains clean and exposed. Check the N-type film pattern: It should only be deposited on the first electrode, with neat edges and no excess deposit extending into non-target areas. If individual splash particles are found in other areas, they can be gently removed under a microscope using a fine-point blade or by lightly removing them with adhesive tape. Afterward, gently wipe the guide tube surface with anhydrous ethanol swabs to remove any possible dust, and blow dry. At this point, the first electrode is covered with an N-type semiconductor layer, while the second electrode remains exposed, ready for the next step of P-type material deposition.

[0135] S8, P-type semiconductor deposition mask setup: Similar to step S5, before depositing the P-type thermoelectric material, the conduit is shielded to ensure that the P-type material is deposited only in the second electrode region. The cleaned mask is repositioned so that its opening aligns with the second electrode region and covers other areas, including the first electrode region. The mask is fixed to ensure it does not shift during deposition. It is then confirmed that only the second electrode region is exposed within the mask window, with no other conduit portions exposed, before proceeding with the P-type material deposition process.

[0136] S9, Deposit P-type semiconductor thermoelectric material layer: Deposit a P-type semiconductor thermoelectric material thin film in the second electrode region exposed by the mask. A magnetron sputtering process similar to N-type deposition is preferred, but the target material is replaced with a P-type (Bi,Sb)₂Te₃ alloy (e.g., Bi₀.₅Sb₁.₅Te₃, which has excellent room-temperature thermoelectric properties). Place the conduit back into the sputtering chamber, maintaining the substrate vacuum below 1 × 10⁻³ Pa. Introduce high-purity argon gas to a working pressure of approximately 0.3 Pa, and set the RF sputtering power to 100–300 W. If the substrate allows, the substrate can be heated to 50–100 °C to improve film quality (if N-type film deposition is complete, the P-type deposition temperature should be controlled to not exceed the previous annealing temperature to avoid affecting the N-type layer properties, such as controlling it at around 100 °C). The deposition process also employs staged or low-speed deposition to achieve the desired thickness (e.g., 5–15 μm, comparable to the N-type layer) and ensure accurate composition. By controlling the Bi / Sb ratio and sputtering rate, the stoichiometry and doping concentration of the P-type thin film are ensured to meet design requirements, resulting in high Seebeck coefficient and conductivity at room temperature. After deposition, a heat treatment similar to that of the N-type layer is performed: annealing at approximately 100°C for 30 minutes in an inert atmosphere helps eliminate internal stress and increase grain size, thereby reducing interface scattering and improving thermoelectric figure of merit. After cooling to room temperature, a P-type semiconductor thin film covering the second electrode is obtained, with a thickness of approximately 5 μm (controlled within ±1 μm according to design tolerance), a smooth surface, and strong adhesion to the bottom electrode.

[0137] S10, Remove the P-type deposition mask: After P-type material deposition and cooling, remove the mask used in step S8. Loosen the fixing device and remove the mask, avoiding scratching the surface of the newly deposited P-type film. Inspect and clean the conduit surface: Confirm that the P-type film is strictly confined to the second electrode region and is not connected to or short-circuited with the N-type film in the first region. If a very small amount of P-type material is found sputtered to the edge of the N-type region due to mask gaps, it should be removed using fine mechanical methods to ensure that the two semiconductor regions are electrically completely isolated. After cleaning, blow away surface particles again with a dust-free airflow. At this point, N-type and P-type semiconductor thin film elements spaced apart from each other have been formed on the conduit surface, respectively attached to two adjacent but insulated metal bottom electrodes;

[0138] S11, Top Electrode Connection Layer Fabrication: A series of conductive top electrode connections are formed above the N-type and P-type semiconductor elements to constitute a thermoelectric circuit. First, the surfaces of the N-type and P-type elements are cleaned to ensure they are free of oxides and contaminants; a light plasma bombardment for several seconds can improve metal-to-metal contact reliability. Then, conductive bridging regions are introduced between the N-type and P-type elements using a mask or screen printing method. For example, a custom-designed open mask is used: its opening is designed to cover the top surface of the N-type element and extend across the gap between the two elements to the top surface of the P-type element, thus connecting them. This mask is accurately positioned and fixed on a conduit, and a top connection metal layer is deposited by magnetron sputtering. A highly conductive and ductile metal, such as gold (Au) or silver (Ag), is preferably deposited. A thin layer of titanium (Ti) or chromium (Cr) (approximately 20 nm thick) can be sputtered first as an adhesion layer to improve the bonding force between the metal and the thermoelectric material surface. Then, Au is sputtered, with a thickness of, for example, 1–3 μm, at a deposition rate of approximately 2–5 nm / s under argon pressure of 0.5 Pa and sputtering power of 100 W, until a continuous metal bridging layer is formed at the mask opening. This top electrode layer spans the top surfaces of both the N-type and P-type elements, covering a certain area (e.g., 50–100% of the top area of ​​each thermoelectric element to reduce contact resistance), and forms a bridge in the mask opening region between them, thus electrically connecting the two thermoelectric elements in series. After deposition, the mask is removed, yielding a regularly shaped top connecting electrode. This top electrode electrically connects one end of the N-type and P-type elements, while the other ends of the two elements are powered through their respective bottom electrodes, thus forming a complete thermoelectric cooling circuit. It is important to note that the top electrode metal must not directly contact the bottom electrode to avoid short circuits. In actual fabrication, the mask position and bridging width (e.g., approximately 0.5 mm) are precisely controlled to ensure that the bridging metal only connects the tops of the two semiconductor components. After the top electrode is formed, the resistance between the two bottom electrodes can be measured to preliminarily verify the correctness of the electrical connection (at this point, the total resistance of the N-type and P-type components connected in series should be measurable).

[0139] S12, Lead-out Connection: To facilitate the subsequent integration of the thermoelectric cooler into the power supply circuit, wires need to be connected as electrical leads in the bottom electrode area. Fine-diameter wires (such as 0.1mm diameter tinned copper wire) are fixed to the bottom electrodes of the first and second zones respectively. A conductive adhesive bonding method is preferred: apply an appropriate amount of silver paste conductive adhesive (high solids content, excellent conductivity epoxy silver paste) to the surface of each bottom electrode pad, press the stripped wire end onto it, and then heat at 60–80°C for 30–60 minutes to cure the conductive adhesive. After curing, the wire should adhere firmly to the electrode with extremely low contact resistance. Low-temperature brazing (e.g., using low-melting-point solder with a melting point ≤150°C) can also be used to achieve wire connection while ensuring the conduit is not damaged by heat. Regardless of the method used, after the lead connection is completed, a multimeter should be used to test the continuity resistance between the wire and the corresponding bottom electrode, as well as the insulation between the two wires, to ensure reliable lead-out connection and good insulation between them.

[0140] S13, Encapsulation and Protection: Surface encapsulation of the cooling device improves mechanical strength and environmental stability, meeting biocompatibility requirements for medical use. A flexible protective material is integrally encapsulated on the N-type and P-type thermoelectric elements and connecting electrodes on the outer surface of the catheter. The protective layer material should possess electrical insulation, moisture resistance, and flexibility, such as medical-grade silicone rubber, epoxy resin, or Parylene film. Parylene C chemical vapor deposition is preferred: the entire catheter is placed in a Parylene deposition apparatus, and the dimer is vaporized and polymerized in a vacuum at room temperature to form a uniformly covered polymer film. The encapsulation layer thickness is controlled between 10 and 30 μm to adequately cover all devices and wire solder joints to form a barrier, without excessively increasing the device thickness and affecting flexibility and heat transfer performance. For solutions using liquid coating materials (such as silicone or epoxy resin), the catheter can be uniformly dipped or sprayed with the protective coating, and then cured for several hours within a range of room temperature to 60°C to allow the coating to solidify. During encapsulation, care should be taken to avoid blockage within the conduit cavity, and the lead wires should be left exposed outside the encapsulation layer for easy electrical connection. After encapsulation and curing, the various layers of the thermoelectric chip are fixed as a whole, making it difficult for external moisture and mechanical abrasion to directly contact the internal thermoelectric elements and electrodes, thereby improving the reliability and lifespan of the device. The final encapsulated flexible semiconductor thermoelectric chip appears to be integrated with the surface of the conduit, maintaining a certain degree of transparency or translucency for observation, without affecting the original flexibility and bendability of the conduit.

[0141] S14, Quality Inspection and Performance Testing: A comprehensive inspection is performed on the packaged flexible semiconductor refrigeration chip to ensure product quality meets requirements. First, an appearance and structural inspection is conducted: the device surface is observed under a microscope to confirm the integrity of the encapsulation layer (free of bubbles and cracks), the absence of film peeling, and the secure connection of the wires. The sensor and refrigeration chip, after encapsulation, have leads laid along the tube wall, exiting through a standard Luer interface or dedicated electrical interface near the tube end. These leads are connected to an external MCU control system via drive cables, powered by an external power supply (DC 12–24 V) or a built-in rechargeable battery pack. Next, electrical performance testing is performed: the resistance between the two leads is measured using a multimeter or a four-probe method to verify that it matches the design value and that the contact resistance is negligible. Further thermoelectric performance is measured. Under constant temperature conditions (e.g., room temperature 25°C), the two leads of the refrigeration chip are connected to an adjustable DC power supply with the design current (e.g., 0.1–0.5A) and driven steadily for several minutes. A temperature sensor is placed on the inner surface of the conduit or at the cold end of the cooling chip to monitor temperature changes and record the temperature drop ΔT at the cold end relative to when no current is applied. Typically, the self-cooling chip should be able to generate a temperature difference of, for example, 2–5°C (depending on the thickness of the thermoelectric material and thermal management conditions) to demonstrate its expected cooling function. Simultaneously, the power is turned off after a certain period of energization, and the temperature recovery is observed to assess the device's thermal cycling stability. Mechanical performance tests can also be performed, such as repeatedly bending the conduit (bending radius approximately 5 cm, repeated bending 20 times) and then testing the resistance and cooling performance again to ensure the device maintains stable performance under repeated bending. All tests should comply with relevant medical device standards. After the above rigorous testing, if all product indicators are qualified, the process of fabricating a flexible semiconductor cooling chip on a flexible endotracheal conduit is complete, and the resulting cooling chip device has reliable performance and meets practical application requirements.

[0142] Selective brain cooling clinical application test

[0143] This invention's device underwent comprehensive testing and verification for situations requiring brain protection, such as post-cardiopulmonary resuscitation brain protection, acute stroke, and severe traumatic brain injury. The effectiveness and safety of the endotracheal tube device in selectively cooling the brain were evaluated through high-fidelity mannequin experiments, animal experiments, and clinical patient trials. In all experiments, the endotracheal tube with cooling function of this invention was used for endotracheal intubation. A rotating permanent magnet positioning system assisted in precise insertion and positioning of the tube at an appropriate depth in the trachea (cooling area corresponding to the pharynx). After successful intubation, the temperature and humidity control system was activated: the temperature of the outer wall of the endotracheal tube was gradually reduced to approximately 18–20°C (controlled within the range of 17–21°C), while the inner wall of the tube was heated to approximately 37°C to ensure that the gas entering the airway maintained normal body temperature and humidity. Brain temperature was continuously monitored using a temperature probe placed in the nasopharynx (as a brain temperature indicator), and core body temperature (a systemic temperature indicator) was monitored using a bladder thermometer. During the cooling intervention, conventional warming measures such as insulating blankets were used to maintain trunk body temperature to reduce the impact of systemic cooling. After a certain period of intervention, cooling was gradually stopped in each group: in the simulation model and animal experiments, cooling lasted for 30–60 minutes; in the clinical patient group, cooling was maintained for about 2 hours, and then the control system slowly warmed the body at a rate of about 1°C per hour until the body temperature approached baseline. Vital signs and potential complications were closely monitored throughout the cooling and rewarming process.

[0144] High-fidelity human body model experiment

[0145] Five repeated experiments were conducted using a highly realistic simulated patient model to simulate the selective cooling process of the brain in a clinical emergency scenario. Heating elements were embedded in the head and torso of the model to maintain the initial "brain temperature" and "body temperature" at approximately 37°C. The endotracheal tube of this invention was inserted orally into the model's airway to the designated location. The cooling device was activated to perform local cooling intervention for 30 minutes according to the above parameters, and then the cooling was stopped, allowing the model to recover to its initial temperature on its own. The simulated "brain temperature" (nasopharyngeal sensor temperature) and "whole body" temperature (torso sensor temperature) were recorded before and after the intervention. Baseline and lowest intervention temperatures, as well as the magnitude of temperature changes, were statistically analyzed. The results are shown in Table 1. As shown in Table 1, the brain temperature of the simulated human model decreased from an average baseline of approximately 37.0°C to a minimum of approximately 34.0°C, a decrease of approximately 3°C, while the "whole body" temperature of the model only decreased from 37.3°C to approximately 35.5°C during the same period, a decrease of approximately 1.8°C. The decrease in brain temperature was significantly greater than the decrease in whole body temperature, and the difference was statistically significant (p < 0.05). Since the simulation model lacks metabolic and circulatory regulatory factors, no chills, heart rate or blood pressure fluctuations occurred throughout the process.

[0146] Table 1. Temperature changes in the brain and whole body in a high-fidelity simulation model (n=5)

[0147]

[0148] *Note: Temperature change is the difference between the lowest temperature during intervention and the baseline temperature; 95% CI is the 95% confidence interval; WT represents the Wilcoxon rank-sum test. The above results used nonparametric tests to compare the difference between the decrease in brain temperature and the decrease in whole-body temperature. It can be seen that using this invention, a local temperature reduction of approximately 3°C was achieved in a simulated human body model, while the whole-body temperature decreased by less than 2°C.

[0149] Example 2: Animal Experiment with Pigs

[0150] The effectiveness and safety of the selective brain cooling method of this invention were further verified in animal models. Ten healthy adult domestic pigs (weighing approximately 30 kg) were selected. After anesthesia, the device of this invention was inserted into the endotracheal tube via orotracheal intubation to replace the conventional endotracheal tube. The angle of the distal end of the tube was adjusted using an external permanent magnet rotation positioning system so that the cooling part of the tube was in close contact with the posterior pharyngeal wall anatomical area. A ventilator was connected to maintain ventilation under anesthesia. After the esophageal temperature and subdural brain temperature (temperature probe placed through a cranial burr hole) of the pigs were maintained at ~38°C during the stable period, the cooling device was activated for selective brain cooling. The temperature of the outer wall of the endotracheal tube was controlled at approximately 18°C, and the internal ventilation temperature was maintained at approximately 37°C. Cooling lasted for 60 minutes. During this period, brain temperature (subdural probe) and core body temperature (rectal temperature) were continuously monitored, and changes in circulation and respiration were observed. After 60 minutes, cooling was stopped, and warmed gas was ventilated through the tube for 15 minutes to assist rewarming. No shivering was observed in the animals during the experiment, and heart rate and arterial blood pressure remained stable during the cooling process. All experimental pigs had intact pharyngeal mucosa, with no signs of local hypothermic damage to the duct. Temperature data before and after cooling are shown in Table 2.

[0151] The results showed that in animal experiments, the average brain temperature in pigs decreased from a baseline of approximately 38.1°C to around 34.0°C, a reduction of about 4.1°C, while the rectal temperature decreased from approximately 38.1°C to only 37.2°C, a reduction of less than 1°C. This indicates that in a pig model, the present invention can significantly reduce brain temperature by approximately 4°C within one hour, while having minimal impact on systemic body temperature. Statistical analysis showed that the reduction in brain temperature was significantly greater than the reduction in core body temperature (p≈0.001).

[0152] Table 2. Temperature changes in the selective brain cooling experiment in pigs (n=10)

[0153]

[0154] *Note: Temperature change is the difference between the lowest temperature during intervention and the baseline temperature; 95% CI is the 95% confidence interval; P-value was calculated using a paired t-test. The results show that a significant reduction in brain temperature with only slight changes in overall body temperature was achieved in the animal model, demonstrating that the device of this invention has a selective brain cooling effect and is safe and feasible.

[0155] Example 3: Preliminary clinical trial

[0156] With ethical approval and informed consent obtained, a preliminary clinical trial of the device of this invention was conducted on 20 critically ill patients to evaluate its cooling effect and safety under actual clinical conditions. Patients included comatose patients who had regained spontaneous circulation after cardiopulmonary resuscitation, patients with large-area ischemic stroke, and patients with severe traumatic brain injury (aged 18–65 years, both male and female). All patients received sedation and intubation in the ICU, replacing their conventional endotracheal tubes with the selective cooling endotracheal tube of this invention (the process was successfully completed under close monitoring). After intubation, cooling was initiated according to the aforementioned parameters: target temperature of the outer wall of the tube approximately 20°C, and constant internal ventilation temperature of 37°C. To prevent shivering, adequate sedation and analgesia were administered during cooling induction, with muscle relaxants added as needed. Baseline body temperature before cooling (nasopharyngeal temperature represents brain temperature, bladder temperature represents core temperature) and the lowest brain and core temperatures during cooling were recorded. Each patient underwent gradual rewarming after approximately 2 hours of cooling. During the cooling process, most patients' vital signs remained stable. A few patients experienced manageable physiological responses: for example, two patients experienced mild bradycardia (minimum heart rate of approximately 50 beats / min, requiring no special treatment), and three patients experienced a slight increase in mean arterial pressure of approximately 10 mmHg (possibly related to peripheral vasoconstriction). No serious complications such as arrhythmias occurred. No significant chills were observed in any patient, and no adverse reactions such as hypotension occurred during rewarming. Table 3 summarizes the results of body temperature changes in the clinical patient group. On average, the patients' brain temperature decreased from a baseline of approximately 37.5°C to a minimum of approximately 34.2°C, a reduction of approximately 3.3°C; during the same period, the core body temperature decreased from approximately 37.6°C to approximately 35.8°C, a reduction of approximately 1.8°C. Statistical analysis showed that the decrease in brain temperature was significantly greater than the decrease in core temperature (p<0.001), demonstrating that the present invention can also achieve selective brain cooling in human patients. This trial preliminarily demonstrated the safety of the present invention: no significant adverse reactions or complications caused by the cooling device were observed in the 20 patients observed. Following the fever-reducing intervention, all patients continued treatment according to standard intensive care protocols. These clinical results strongly support the application of this invention in critically ill patients.

[0157] Table 3. Temperature changes in clinical patients during selective brain hypothermia testing (n=20)

[0158]

[0159] *Note: Temperature change is the difference between the lowest temperature during intervention and the baseline temperature; 95% CI is the 95% confidence interval; P-value was calculated using a paired t-test. The above clinical data demonstrate that the endotracheal tube device of this invention achieved an average selective brain cooling effect of approximately 3–4°C in critically ill patients, while only slightly decreasing overall body temperature, with no serious adverse events occurring. This provides a new technical means and reliable data support for selective brain cooling in clinical situations such as brain protection after cardiac arrest, ischemic stroke, and brain trauma.

Claims

1. A tracheal tube device with rotating permanent magnet positioning and selective brain cooling function, characterized in that: Includes endotracheal tube (1), temperature and humidity control system and rotating permanent magnet positioning system; Several flexible semiconductor cooling chips (2) are embedded in the flexible tracheal tube (1) at certain intervals along the extension direction of the tube; the cold end of all the flexible semiconductor cooling chips (2) is in contact with the outer wall of the tracheal tube, and the hot end of the flexible semiconductor cooling chips (2) is in contact with the inner wall of the tracheal tube (1); several temperature and humidity sensors (3) are arranged at intervals between the multiple flexible semiconductor cooling chips (2) on the tracheal tube (1), and the humidity and temperature of the gas at different positions in the tracheal tube (1) are obtained through each temperature and humidity sensor (3); The temperature and humidity control system is used to dynamically adjust the voltage and current values ​​at both ends of each flexible semiconductor cooling chip (2), obtain the temperature and humidity values ​​of the tracheal tube (1) through each temperature and humidity sensor (3), and combine them with the set target temperature threshold. PID control is used to dynamically adjust the voltage of each flexible semiconductor cooling chip (2) to control the internal temperature of the tracheal tube to a fixed constant temperature. The rotating permanent magnet positioning system includes an external magnetic field generating device, a tracheal tube assembly, and a control module. The external magnetic field generating device includes a permanent magnet and a permanent magnet driving mechanism. The permanent magnet driving mechanism includes a permanent magnet three-axis driving mechanism and a robotic arm. The permanent magnet three-axis driving mechanism is mounted on the robotic arm and drives the permanent magnet to rotate and adjust the direction of the magnetic field through the three-axis driving mechanism. The tracheal tube assembly includes a magnetic guiding element (5) and a magnetic sensor (4) set at the distal end of the tracheal tube (1). The magnetic guiding element is used to generate a guiding force under the action of the external magnetic field. The magnetic sensor (4) is set close to the magnetic guiding element and is used to detect the strength and direction of the external magnetic field and provide feedback signals. The control module includes a signal processing unit and an execution unit. It is used to acquire analog signals from the magnetic sensor and control the motor of the permanent magnet three-axis drive mechanism through PWM signals, thereby adjusting the rotation angle of the permanent magnet. The software algorithm built into the control module adjusts the magnetic field in real time based on the feedback from the magnetic sensor. By adjusting the strength and direction of the external magnetic field in real time through the control module, the position and angle of the magnetic guiding element at the distal end of the endotracheal tube are precisely controlled to achieve accurate positioning of the tube.

2. The endotracheal tube device with rotating permanent magnet positioning and selective brain cooling function according to claim 1, characterized in that: The temperature and humidity control system includes a MCU module, multiple temperature and humidity sensors (3) connected to the MCU control module, a DC-DC converter connected to the MCU, the MCU control module connected to the MOS transistor after being isolated by an optocoupler, each flexible semiconductor cooling chip (2) connected to a MOS transistor and a DC-DC converter, each MOS transistor and DC-DC converter being individually controlled by the MCU control module, the output voltage being adjusted by the DC-DC converter, the output current being adjusted by the power MOS transistor through the PWM signal, and the temperature being adjusted automatically by adjusting the voltage across the flexible semiconductor cooling chip (2) in different areas after the temperature is set by the MCU control module.

3. The endotracheal tube device with rotating permanent magnet positioning and selective brain cooling function according to claim 2, characterized in that: The MCU control module is connected to a current acquisition circuit and a voltage acquisition circuit. The current acquisition circuit and voltage acquisition circuit monitor the actual current and voltage output to each flexible semiconductor cooling chip (2) and feed them back to the MCU control module. The current acquisition circuit samples the INA180A2IDBVR current sensing amplifier, and the voltage acquisition circuit samples the output voltage using voltage divider resistors.

4. The endotracheal tube device with rotating permanent magnet positioning and selective brain cooling function according to claim 3, characterized in that: The MCU control module is also equipped with a display module. The MCU control module processes, filters, and calibrates the collected temperature and humidity data, and then uses a coordinate mapping algorithm to draw curves, mapping the collected temperature and humidity data onto the coordinate system of the display module. The MCU control module converts the analog voltage signal into a digital signal through its built-in ADC module for the collected current and voltage data of each flexible semiconductor cooling chip (2), and converts the collected voltage and current data into coordinate values ​​to draw curves through a preset algorithm, and displays the voltage and current curves on the display module.

5. The endotracheal tube device with rotating permanent magnet positioning and selective brain cooling function according to any one of claims 1-4, characterized in that: The MCU control module is connected to a storage device to store the collected voltage, current and temperature and humidity data in the storage device; the magnetic sensor is a Hall sensor or a magnetoresistive sensor; the temperature and humidity sensor (3) is a thin-film digital sensor.

6. The endotracheal tube device with rotating permanent magnet positioning and selective brain cooling function according to claim 5, characterized in that: The permanent magnet triaxial drive mechanism includes a permanent magnet (6), a permanent magnet drive motor (8), and an inner ring (9). The permanent magnet (6) and the permanent magnet drive motor (8) are installed inside the inner ring (9). The permanent magnet drive motor (8) is installed on the inner ring (9) to drive the permanent magnet (6) to rotate and change its magnetic field direction and angle. The inner ring drive motor (10) is connected to the inner ring (9) to drive the inner ring to rotate relative to the outer ring (12). The inner ring position encoder (11) is used to monitor the rotation position and angle of the inner ring (9) in real time. The outer ring (12) serves as the external support structure for the inner ring (9) and internal components. The outer ring drive motor (13) is connected to the outer ring (12) to drive the outer ring to rotate. The outer ring position encoder (14) is used to monitor the rotation position and angle of the outer ring (12). The outer shell (15) serves as the external protection structure for the entire triaxial drive mechanism.

7. The endotracheal tube device with rotating permanent magnet positioning and selective brain cooling function as described in any one of claims 1-4, characterized in that: The temperature and humidity control system uses PID control according to formula (1) to control the voltage of the semiconductor cooling chip; u ( t )= K p e ( t )+ K i dτ + K d dtde ( t )（1） in: u ( t The output of the controller is the voltage across the flexible semiconductor refrigeration chip. e ( t )= Tset Tactual ( t (This is the set temperature) Tset Compared with the actual measured temperature Tactual ( t The error between ) K p It is proportional gain. K i It is integral gain. K d It is the differential gain; To achieve adaptive adjustment of PID parameters, a neural network-optimized PID temperature controller is constructed by combining a feedforward neural network (MLP) with PID control. The feedforward MLP outputs the optimal PID gain in real time based on the current state characteristics. This enables the controller to self-adjust as the environment and target change; the temperature and physiological parameters of the gas at different positions in the tracheal tube (1) obtained by each temperature and humidity sensor (3) are used as the input of the feedforward neural network MLP, and the network output updates the parameters of the PID controller in real time. The PID controller calculates the voltage of the cooling chip based on this and drives the cooling chip to adjust the temperature, forming a closed-loop control.

8. The endotracheal tube device with rotating permanent magnet positioning and selective brain cooling function as described in claim 7, characterized in that: A two-layer feedforward neural network MLP is used as the PID parameter regulator, and the activation function is the linear rectified function ReLU. This enhances the nonlinear expressive power of the network while maintaining the stability of gradient propagation. The output layer has three nodes, each corresponding to a PID controller. , , With three gain parameters and linear activation in the output layer, the feedforward neural network MLP performs the function of processing the input vector. Nonlinear mapping: in, The input feature vector; For multiple points of temperature on the inner wall of the catheter, For multiple temperature points on the outer wall of the catheter, The patient's core body temperature, The temperature of the brain in the nasopharynx. The time that has been spent cooling down, Given the current cooling rate, Set a value for the target temperature or temperature difference; Real-time computation function of neural networks Output the most suitable PID gain combination at the corresponding time. These outputs are directly used by the PID controller to change its parameters over time: This leads to adaptive PID control.

9. The endotracheal tube device with rotating permanent magnet positioning and selective brain cooling function as described in claim 7, characterized in that: During the training of the feedforward neural network MLP, the loss function Defined as the mean square value of temperature control error, for the setpoint of the outer wall temperature of the conduit. Formula (4) is used: in For the first The outer wall temperature is collected at a specific time or the average value of multiple points is taken. If the inner wall temperature error is also considered, the inner wall temperature deviation term is added to the loss function with weights, and the overall loss function is then considered. By selecting weights While ensuring the accuracy of external wall temperature control, it limits the deviation of internal wall temperature from normal body temperature.

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