Tracheal catheter device with rotary permanent magnet positioning and selective brain cooling functions and temperature control method thereof

Abstract

The invention discloses a tracheal catheter device with rotary permanent magnet positioning and selective brain cooling functions and a temperature control method of the tracheal catheter device. A plurality of flexible semiconductor chilling plates and a plurality of temperature and humidity sensors are embedded in the inner wall side and the portion, close to the outer wall side, of a flexible tracheal catheter in the catheter extending direction; the function of heating wet gas entering the tracheal catheter is achieved; the outer wall of the trachea cannula is cooled, a local low-temperature environment is achieved, and therefore a certain protection effect on the brain is achieved. The low temperature reduces the metabolic rate of brain cells, reduces oxygen consumption of the brain, contributes to relieving brain injury and improves the brain function recovery effect of a patient; the flexible semiconductor chilling plate and the temperature and humidity sensor are used for accurate temperature control, accurate adjustment of the temperature of the outer wall of the trachea cannula is achieved, adverse effects on the brain protection effect caused by too large temperature fluctuation are avoided, and the method is more targeted and controllable compared with a traditional cooling method.

Description

Technical Field

[0001] The present invention relates to a medical instrument, in particular to a tracheal tube device with rotating permanent magnetic positioning and selective brain cooling functions and a temperature control method thereof. Background Art

[0002] Nasotracheal intubation is one of the methods to establish an artificial airway. It has the advantages of simple operation, easy fixation, convenient oral care, good tolerance, and long catheter retention time. It is now widely used in cranial and oral surgery, trauma emergency, and comatose patients who require long-term ventilator oxygen supply and have a lot of airway secretions. It is especially suitable for patients who have difficulty opening their mouths and cannot be placed with a laryngoscope.

[0003] Currently, nasotracheal intubation generally uses the Endotrol catheter traction method. A removable guide wire is embedded in the inner wall of the endotracheal tube. Its distal end is fixed to the distal end of the endotracheal tube, and its proximal end is extended from the proximal end of the endotracheal tube. By pulling on the metal ring, the distal end of the endotracheal tube can be tilted, achieving nasotracheal intubation. However, this method still has a low intubation success rate. According to statistics, the intubation success rate is only 70%. Repeated intubations not only cause great pain to the patient, but if the endotracheal tube enters the esophagus of a comatose patient, it often leads to insufficient oxygen supply for the patient, resulting in anesthesia malpractice claims. Therefore, there is an urgent need for a method to effectively detect the current end position of the endotracheal tube and provide timely notification of incorrect positions, so that medical staff can be informed of intubation accidents such as position deviation during the intubation process.

[0004] Furthermore, the gas introduced through an artificial airway lacks the normal heating and humidification capabilities of the human body, causing significant discomfort to the patient. Following endotracheal intubation, patients with severe pneumonia routinely require heating and humidification of the delivered gas. This helps maintain a normal airway environment in the patient's airway, mimicking a normal airway and improving weaning rates from invasive ventilation. After establishing an artificial airway, the endotracheal tube is connected to a ventilator equipped with a heating and humidification device. However, since the ambient temperature in the operating room is generally maintained between 21-25°C, while the normal human respiratory temperature is generally between 37.2 and 37.7°C, a significant temperature difference exists. The heated and humidified gas, which is close to human body temperature, often cools in the tube after passing through it, generating condensation. This condenses the water vapor that would otherwise enter the lungs, reducing the humidification level and causing negative effects such as invisible dehydration. Furthermore, the entry of air cooled by the outdoor environment into the lungs can cause mucociliary dysfunction and impair sputum excretion. Therefore, there is an urgent need for a method to effectively increase the temperature of the inner wall of the tracheal tube to prevent gas condensation and condensation during gas transmission and the occurrence of gas temperature drop.

[0005] Currently, maintaining low brain temperature is an effective treatment and protection method for patients with severe craniocerebral trauma, stroke, or severe craniocerebral trauma. Hypothermia reduces metabolic rate by reducing cellular glucose and oxygen consumption, thereby promoting neuroprotection and prolonging cell survival. Selective brain cooling prevents the harmful effects of systemic hypothermia. Currently, researchers have achieved selective brain cooling by circulating cold water in a closed-loop nasopharyngeal catheter. However, this device still has problems such as inaccurate temperature control of the cold water circulation and excessive size of the water circulation equipment. At the same time, the current endotracheal intubation device itself does not have a cooling circulation system. Therefore, there is an urgent need for a method to cool and absorb heat between the outer wall of the endotracheal tube and the nasal cavity and throat during nasotracheal intubation to achieve selective brain cooling. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide a tracheal tube device with rotating permanent magnetic positioning and selective brain cooling function and a temperature control method thereof, so as to cool the outer wall of the tracheal tube while heating the airflow in the tracheal tube through the inner wall of the tracheal tube.

[0007] The present invention is achieved through the following technical solutions: A tracheal tube device with rotating permanent magnetic positioning and selective brain cooling functions, comprising a tracheal tube, a temperature and humidity control system, and a rotating permanent magnetic positioning system; A plurality of flexible semiconductor cooling sheets are embedded in the flexible endotracheal tube at intervals along the extension direction of the tube; the cold ends of all the flexible semiconductor cooling sheets are in contact with the outer wall of the endotracheal tube, and the hot ends of the flexible semiconductor cooling sheets are in contact with the inner wall of the endotracheal tube; a plurality of temperature and humidity sensors are arranged between the plurality of flexible semiconductor cooling sheets on the endotracheal tube, and the humidity and temperature of the gas at different positions in the endotracheal tube are obtained through each temperature and humidity sensor; 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 by each temperature and humidity sensor. In combination 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. The rotating permanent magnet positioning system includes an external magnetic field generating device, an endotracheal tube assembly, and a control module. The external magnetic field generating device includes a permanent magnet and a permanent magnet drive mechanism. The permanent magnet drive mechanism includes a permanent magnet three-axis drive mechanism and a robotic arm. The permanent magnet 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 through the three-axis drive mechanism. The endotracheal tube assembly includes a magnetic guide element and a magnetic sensor disposed at the distal end of the endotracheal tube. The magnetic guide element is used to generate a guiding force under the action of the external magnetic field. The magnetic sensor is disposed adjacent to the magnetic guide element and is used to detect the strength and direction of the external magnetic field and provide a feedback signal. The control module includes a signal processing unit and an execution unit, which are used to collect 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 feedback from the magnetic sensor. The control module adjusts the intensity and direction of the external magnetic field in real time, accurately controlling the position and angle of the magnetic guide element at the distal end of the endotracheal tube to achieve precise positioning of the tube.

[0008] Preferably, the temperature and humidity control system includes a MUC module, multiple temperature and humidity sensors are connected to the MCU control module, the DC-DC converter is connected to the MUC, the MCU control module is isolated from the MOS tube by an optocoupler and connected, each flexible semiconductor refrigeration plate is connected to a MOS tube and a DC-DC converter, each MOS tube and DC-DC converter is separately controlled by the MCU control module, the DC-DC converter is used to adjust the output voltage, and the power MOS tube is used to adjust the output current through the PWM signal. After the temperature is set by the MCU control module, the voltage across the flexible semiconductor refrigeration plates in different areas is automatically adjusted to achieve temperature and humidity regulation.

[0009] Preferably, the MCU control module is connected to a current acquisition circuit and a voltage acquisition circuit, which monitor the current and voltage actually output to each flexible semiconductor refrigeration plate through the current acquisition circuit and the voltage acquisition circuit and feed back to the MCU control module; the current acquisition circuit samples the INA180A2IDBVR current detection amplifier, and the voltage acquisition circuit samples the output voltage through a voltage divider resistor.

[0010] 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 a curve, and maps the collected temperature and humidity data to the coordinate system of the display module; the MCU control module collects the current and voltage data of each flexible semiconductor refrigeration plate, converts the analog voltage signal into a digital signal through its own ADC module, converts the collected voltage and current data into coordinate values ​​through a preset algorithm to draw a curve, and displays the voltage and current curves on the display module.

[0011] Preferably, the MCU control module is connected to a storage device to store the collected voltage, current, temperature and humidity data in the storage device; the temperature and humidity control system is also connected to an alarm module; the magnetic sensor adopts a Hall sensor or a magnetoresistive sensor; the temperature and humidity sensor adopts a thin-film digital sensor.

[0012] Preferably, the permanent magnet three-axis drive mechanism includes a permanent magnet, the permanent magnet and the permanent magnet drive motor are installed in the inner ring, the permanent magnet drive motor is installed on the inner ring to drive the permanent magnet to rotate and change its magnetic field direction and angle, the inner ring drive motor is connected to the inner ring to drive the inner ring to rotate relative to the outer ring, the inner ring position encoder is used to monitor the rotation position and angle of the inner ring in real time, the outer ring serves as the external support structure of the inner ring and internal components, the outer ring drive motor is connected to the outer ring to drive the outer ring to rotate, the outer ring position encoder is used to monitor the rotation position and angle of the outer ring, and the outer shell serves as the external protection structure of the entire three-axis drive mechanism.

[0013] On the other hand, the present invention provides a temperature control method for an endotracheal tube device with a rotating permanent magnet positioning and a selective brain cooling function, wherein the temperature and humidity control system uses PID control according to formula (1) to control the voltage of the semiconductor refrigeration chip; u ( t )= K p e ( t )+ K i dτ + K d dtde ( t )(1) in: u ( t ) is the output of the controller, that is, the voltage across the flexible semiconductor refrigeration sheet. e ( t )= Tset − Tactual ( t ) is the set temperature Tset The actual measured temperature Tactual ( t ), K p is the proportional gain, K i is the integral gain, K d is the differential gain; In order to achieve adaptive adjustment of PID parameters, a neural network optimized PID temperature controller is constructed by combining feedforward neural network MLP with PID control; the feedforward neural network MLP outputs the optimal PID gain in real time according to the current state characteristics. , so that the controller can self-regulate with the changes of environment and target; 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 instantly updates the parameters of the PID controller. The PID controller calculates the voltage of the cooling plate based on this, drives the cooling plate to adjust the temperature, and forms a closed-loop control.

[0014] Preferably, a two-layer feedforward neural network MLP is used as the PID parameter regulator, and the activation function is the linear rectifier function ReLU ( ) to enhance the nonlinear expression ability of the network while maintaining the stability of gradient propagation; the output layer consists of 3 nodes, corresponding to the PID controller 、 、 Three gain parameters, the output layer uses linear activation, and the function implemented by the feedforward neural network MLP is expressed as the input vector Nonlinear mapping of: in, is the input feature vector; is the temperature at multiple points on the inner wall of the catheter, The temperature of multiple points on the outer wall of the catheter, is the patient's core body temperature, The nasopharyngeal brain temperature is The time for cooling down, is the current cooling rate, Set a value for the target temperature or temperature difference; Neural network real-time calculation function , output the most suitable PID gain combination at the corresponding moment These outputs are used directly in a PID controller to vary its parameters over time: , thus forming an adaptive PID control.

[0015] Preferably, during the training of the feedforward neural network MLP, the loss function Defined as the mean square value of the temperature control error, for the set value of the outer wall temperature of the tube , using formula (4): in For the The outer wall temperature collected at each moment or the average value of multiple points; If the inner wall temperature error is considered at the same time, the inner wall temperature deviation term is weighted and added to the loss function, and the comprehensive loss function is , by choosing the weight While ensuring the accuracy of outer wall temperature control, it limits the deviation of inner wall temperature from normal body temperature.

[0016] The present invention has the following beneficial effects: The present invention embeds a plurality of flexible semiconductor refrigeration sheets and a plurality of temperature and humidity sensors on a flexible tracheal tube at a certain distance along the extension direction of the tube; the cold end of the flexible semiconductor refrigeration sheet contacts the outer wall of the tracheal tube, and the hot end of the flexible semiconductor refrigeration sheet contacts the inner wall of the tracheal tube, thereby achieving the function of heating the humidified gas entering the tracheal tube.

[0017] By cooling the outer wall of the endotracheal tube, a local hypothermia environment is achieved, thus providing a certain degree of protection for the brain. Hypothermia reduces the metabolic rate of brain cells and reduces the brain's oxygen consumption. In situations that lead to cerebral ischemia and hypoxia, such as cardiopulmonary resuscitation, certain brain surgeries, or severe trauma, this helps alleviate brain damage and improve the patient's brain function recovery. Flexible semiconductor refrigeration sheets and temperature and humidity sensors are used for precise temperature control, achieving precise regulation of the outer wall temperature of the endotracheal tube, stabilizing the temperature between 17°C and 21°C, and avoiding excessive temperature fluctuations that may adversely affect brain protection. This is more targeted and controllable than traditional cooling methods (such as whole-body cooling or the use of ice packs).

[0018] Maintaining the inner wall temperature of the endotracheal tube at 37.5°C, the same as the average lung temperature, avoids irritation to the respiratory tract caused by inhaling cold gases and prevents adverse reactions such as respiratory spasms and coughing. This can improve patient comfort and reduce respiratory complications for patients requiring prolonged ventilator use, such as those in the intensive care unit (ICU) or undergoing prolonged anesthesia. Maintaining a stable inner wall temperature of the endotracheal tube helps maintain normal respiratory physiological functions, including mucociliary clearance and the integrity of the respiratory mucosa, helping to prevent sputum thickening and respiratory infections.

[0019] The temperature of the inner and outer walls of the endotracheal tube can be flexibly adjusted to suit individual patient needs and clinical conditions. This personalized temperature regulation 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 based on actual conditions and adjust temperature control strategies according to the patient's physiological state and environmental conditions, helping to improve the quality and safety of treatment.

[0020] By embedding a magnetic element at the end of a flexible endotracheal tube, a magnetic field sensor or detector is used outside the body to accurately sense the position of the tube end. The position of the tube end in the human trachea is accurately determined in three-dimensional space, with accuracy down to the millimeter level. This is crucial for ensuring that the tube is in the optimal position, avoiding excessive or shallow insertion 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 not accurate enough, while magnetic positioning provides more precise position information, reducing the risk of poor ventilation, atelectasis, or other complications due to inaccurate positioning.

[0021] The temperature regulation functions of the inner and outer walls of the endotracheal tube are integrated into the same device, achieving both hypothermia brain protection and respiratory tract protection, realizing multiple therapeutic purposes in one medical device and breaking through the previous limitation of focusing only on airway ventilation function.

[0022] Integrating a flexible semiconductor cooling sheet and temperature and humidity sensors into the design of an endotracheal tube creates a relatively independent temperature regulation system, reducing reliance on complex external equipment and simplifying operation. Through electronic control technology, precise temperature control and real-time monitoring are achieved, providing new insights into the intelligent and sophisticated development of medical devices.

[0023] Advanced control algorithms (such as PID control) and real-time monitoring and feedback mechanisms ensure precise temperature control. Once the temperature is set, the system automatically adjusts the voltage across semiconductor sensors in different zones to achieve precise and stable temperature regulation. This provides more precise conditions for clinical treatment. The measured temperature and humidity of the inner and outer tube walls are exported and plotted as temperature curves, facilitating postoperative care. This is a significant innovation in clinical temperature control. The temperature and humidity sensor monitors the temperature and humidity of the inner and outer walls of the endotracheal tube in real time. Through the feedback system, the operating status of the flexible semiconductor cooling plate can be adjusted promptly, forming a closed-loop control system to ensure that the temperature is always maintained within the set range, improving system reliability and stability.

[0024] A new treatment concept combining hypothermia brain protection and respiratory tract protection has been proposed, unifying the originally independent treatment measures (brain protection and respiratory management) through the temperature regulation system of endotracheal intubation, bringing new methods and means to clinical treatment, and will expand the treatment ideas and methods of clinicians.

[0025] This solution is applicable to more clinical scenarios, not only limited to traditional cardiopulmonary resuscitation and neurosurgery that require brain protection. It provides better treatment conditions for patients with diseases that cause brain damage (such as severe septic shock, cardiac arrest, etc.) or who require long-term mechanical ventilation, and has broader clinical application prospects.

[0026] This invention provides a system for tracking and locating the trachea using a rotating permanent magnet positioning system. The rotating magnetic field generated by an external magnetic field generator interacts with a magnetic sensor on the tracheal tube to achieve precise control and positioning of the tube. A positioning and display module displays the catheter's position and posture in real time, helping doctors accurately insert the catheter into the target location and avoid insertion into the esophagus or other non-target areas.

[0027] The positioning and display module displays the catheter's position and posture in intuitive ways (such as numbers and graphics), allowing doctors to quickly understand the catheter's status and make appropriate adjustments. The rotating permanent magnet positioning system is relatively easy to operate, allowing doctors to master its operation after simple training, helping to shorten surgical procedures and improve efficiency.

[0028] Compared to traditional X-ray imaging positioning methods, the Rotating Permanent Magnetic Positioning System does not require a radiation source, reducing radiation risks to patients and medical staff. The system utilizes high-performance permanent magnetic materials and advanced control technology to ensure safety and reliability, reducing surgical risks.

[0029] The rotary permanent magnet positioning system, through its unique structural design and functional characteristics, has many beneficial effects in the medical field, such as improving intubation accuracy and safety, facilitating easy operation, enhancing adaptability, reducing radiation risks, and promoting the development of medical technology, thus providing patients with a better medical experience and treatment effect.

[0030] The device, which utilizes a neural network to optimize the PID temperature control algorithm, achieves precise control of endotracheal tube temperature and effective selective cooling of the brain. This addresses the shortcomings of existing whole-body cooling technologies, which lack efficiency and controllability, and demonstrates significant innovation and clinical practical value. The design concept of this control system also offers new insights into intelligent temperature control in medical devices, integrating artificial intelligence algorithms with traditional controllers to adapt to the complex human environment, thereby further improving the safety and effectiveness of treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the structure of an endotracheal tube device with rotating permanent magnetic positioning and selective brain cooling functions; Figure 2 This is the principle block diagram of the temperature and humidity control system; Figure 3 This is the PID control principle diagram of the present invention; Figure 4 A temperature curve graph displayed on the display module; Figure 5 Schematic diagram of endotracheal tube use; Figure 6 Schematic diagram of the structure of the permanent magnet driving mechanism in the external magnetic field generating device; Figure 7 Generate a magnetic field profile for a permanent magnet; Figure 8 This is a flow chart of the feedforward neural network training of the present invention; Figure 9 This is the schematic diagram of the feedforward neural network control structure: Figure 10 This is the structure diagram of the neural network PID parameter optimization module; Figure 11 Schematic diagram of the preparation process of the endotracheal tube of the present invention; In the figure: 1- tracheal tube, 2- flexible semiconductor cooling sheet, 3- temperature and humidity sensor, 4- magnetic sensor, 5- magnetic guide element, 6- permanent magnet, 7- permanent magnet three-axis 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 casing. DETAILED DESCRIPTION The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0032] like Figure 1 As shown, the overall structure of the tracheal tube device with rotating permanent magnetic 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 magnetic positioning system.

[0033] Several flexible semiconductor cooling sheets 2 are embedded in a flexible endotracheal tube 1 at regular intervals along its extension. The cold ends of all flexible semiconductor cooling sheets 2 contact the outer wall of the endotracheal tube, lowering throat temperature and providing hypothermia protection. The hot ends of the flexible semiconductor cooling sheets 2 contact the inner wall of the endotracheal tube 1, heating the humidified air entering the tube. Temperature and humidity sensors 3 are also spaced between the flexible semiconductor cooling sheets 2 on the endotracheal tube 1. These sensors dynamically monitor the humidity and temperature of the air at different locations within the endotracheal tube 1, providing secondary protection for the patient.

[0034] The flexible endotracheal tubes described in this invention are soft and flexible, adapting to the anatomy of the human airway and playing a vital role in medical procedures such as anesthesia, emergency treatment, and respiratory support. The tube body is made of medical-grade polymer materials. Some flexible endotracheal tubes feature an inflatable balloon located at the front end of the tube. When inflated, this balloon seals the gap between the trachea and the tube, preventing gas leakage and aspiration. The balloon is made of highly elastic rubber or silicone, capable of withstanding a certain level of air pressure and resisting deformation or rupture during prolonged use. The balloons include high-pressure, low-volume balloons and low-pressure, high-volume balloons. The low-pressure, high-volume balloon exerts relatively less pressure on the tracheal mucosa, reducing the risk of mucosal damage. One end of the tube typically connects to the tubing of an anesthesia machine or ventilator. This connector uses a standard Luer connector or other international standard connector to ensure a tight and reliable connection to the respiratory device. During general anesthesia, flexible endotracheal tubes are used to establish an artificial airway and ensure patient ventilation and oxygenation. The anesthesiologist selects a suitable catheter based on the patient's airway condition, inserts it into the trachea, and performs positive pressure ventilation through the anesthesia machine to provide safe respiratory support for the operation.

[0035] The flexible semiconductor refrigeration sheet used in the present invention is a new type of refrigeration device based on semiconductor materials. In addition to the refrigeration principle of traditional semiconductor refrigeration sheets, it also has the characteristics of flexibility and bendability. It can adapt to surfaces of various complex shapes and special application scenarios, and fit various curved and irregularly shaped surfaces. Like traditional semiconductor refrigeration sheets, the working principle of flexible semiconductor refrigeration sheets is based on the Peltier effect. When direct current passes through a thermocouple composed of an N-type semiconductor and a P-type semiconductor, energy transfer occurs at the junction of the two semiconductors. On one side of the junction, electrons transition from a low energy level to a high energy level, absorbing heat, causing the temperature on that side to drop, achieving a cooling effect; on the other side, electrons transition from a high energy level to a low energy level, releasing heat, causing the temperature on that side to rise. By adjusting the direction and magnitude of the current, the cooling and heating effects can be controlled.

[0036] The temperature and humidity sensor used in this invention is a thin-film digital sensor with excellent linearity and stability. It uses a digital output mode and can be directly connected to digital devices such as microcontrollers. It directly contacts the object being measured and measures temperature and humidity through heat conduction or moisture conduction. Temperature and humidity sensors are placed on the inner and outer walls of the gas conduit to monitor the internal and external temperatures, respectively, providing data for overall temperature regulation.

[0037] like Figure 2As shown, in order to achieve uniform temperature control inside the tracheal tube, a temperature and humidity control system is provided to dynamically adjust the voltage and current values ​​at both ends of each flexible semiconductor refrigeration plate 2 through the circuit. After the temperature and humidity values ​​of the tracheal tube 1 are obtained by each temperature and humidity sensor 3, the PID control is used to dynamically adjust the voltage of each flexible semiconductor refrigeration plate 2 in combination with the set target temperature threshold, so as to control the internal temperature of the tracheal tube to a fixed constant temperature while ensuring that the temperature outside the tube will not be too cold.

[0038] like Figure 3 As shown in FIG, the controller uses PID control according to formula (1) to control the voltage of the semiconductor refrigeration chip to achieve the purpose of controlling the temperature.

[0039] u ( t )= K p e ( t )+ K i dτ + K d dtde ( t )(1) in: u ( t ) is the output of the controller (i.e. the voltage across the flexible semiconductor refrigeration sheet), e ( t )= Tset − Tactual ( t ) is the set temperature Tset The actual measured temperature Tactual ( t ), K p is the proportional gain, which determines the response strength of the controller to the current error. K i is the integral gain, used to eliminate steady-state error, K d It is the differential gain, which is used to predict the changing trend of the error and make adjustments in advance.

[0040] The temperature is measured by setting a temperature and humidity sensor near the flexible semiconductor refrigeration sheet. T 1 and T 2. The PID controller receives the signal from the temperature and humidity sensor and calculates the temperature difference Δ T = T 1− T 2 (or the difference from the set temperature), and then calculate the PID algorithm according to formula (1) u( t ) is the control voltage Vcontrol The flexible semiconductor refrigeration sheet receives the control voltage Vcontrol After the flexible semiconductor refrigeration sheet has finished operating, 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 loop that continuously adjusts the voltage until the desired temperature difference or set temperature is reached.

[0041] To achieve adaptive adjustment of PID parameters, the present invention introduces a feedforward neural network (Multilayer Perceptron, MLP) combined with PID control to form a neural network optimized PID temperature controller. The feedforward neural network MLP outputs the optimal PID gain in real time according to the current state characteristics. , enabling the controller to self-adjust as the environment and goals change.

[0042] like Figure 9 As shown in the figure, 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 instantly updates the parameters of the PID controller. The PID controller calculates the voltage of the cooling plate based on this, drives the cooling plate to adjust the temperature, and forms a closed-loop control.

[0043] Input feature design: The input layer of the feedforward neural network MLP receives multiple sensor information and control state quantities at the same time to fully characterize the current temperature control requirements. In this embodiment, the input features include: the temperature of multiple points on the inner wall of the catheter (e.g. 3 sensor readings evenly distributed along the inner wall of the duct), multiple temperature points on the outer wall of the duct , the patient's core body temperature (such as bladder temperature ), nasopharyngeal brain temperature (as an indicator of brain temperature ), cooling time , current cooling rate (e.g. rate of brain temperature drop per unit time) and target temperature or temperature difference setting value These characteristics reflect the temperature distribution at different locations along the catheter, the overall temperature of the patient and the brain, the stage of the cooling process (initial rapid cooling or maintenance), and the desired temperature control target. The feedforward neural network (MLP) uses this comprehensive information to determine how to adjust the current control strategy.

[0044] Network structure and output: Figure 10As shown in the figure, a two-layer feedforward neural network is used as the PID parameter regulator. The number of input layer nodes corresponds to the above-mentioned feature dimensions, and there are no less than a dozen nodes in total. The hidden layer is set to 1 to 2 layers, each layer contains an appropriate number of neurons (for example, 10-20 per layer), and the activation function uses the linear rectifier function ReLU ( ) to enhance the nonlinear expression ability of the network while maintaining the stability of gradient propagation. The output layer consists of 3 nodes, corresponding to the PID controller 、 、 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 expressed as the input vector Nonlinear mapping of: in is the input feature vector. Neural network real-time calculation function , output the most suitable PID gain combination at the corresponding moment These outputs are used directly in a PID controller to vary its parameters over time: , thus forming an adaptive PID control. At this time, the control law of the controller can be expressed as: Similar to formula (1), but the PID gain is no longer fixed, but is given by the feedforward neural network MLP according to the state dynamics In this way, when the system is in different temperature stages or faces different individual differences, the controller's "strength" will automatically adjust, providing sufficient control during the rapid cooling stage, while also smoothly converging to avoid overshoot when approaching the target, and taking into account the comprehensive control of the patient's core body temperature and local brain temperature.

[0045] Control strategy features: The neural network optimized PID controller combines the robustness of classical control with the self-learning ability of intelligent control. When the outer wall temperature of the catheter deviates from the target or the inner wall temperature of the catheter fluctuates abnormally, the network adjusts the PID gain in time based on multi-point sensor information to correct the temperature deviation. For example, if it is detected that the brain temperature drops too quickly, which may cause systemic side effects, the network can reduce Slow down the cooling rate; on the contrary, if the brain temperature drops slowly within the safe range, it will increase and Enhanced cooling power. Furthermore, multi-point temperature feedback enables the network to balance the temperature distribution across sections. If the outer wall temperature of a particular section of the duct is detected to be lower than that of other locations, the power output of the cooling fins in that section can be specifically reduced. This translates to increased PID gain in areas with large local errors, leading to more active compensation. This ensures consistent temperatures at all sensing points, resulting in a more uniform temperature distribution along the duct. In summary, the neural network-optimized PID structure makes the temperature control system more adaptable to nonlinear and time-varying characteristics, and provides improved control performance.

[0046] Training data sources and network training methods like Figure 8 As shown, in order to enable the feedforward neural network MLP to correctly map the temperature state to the PID control parameters, it is necessary to use a large amount of experimental and clinical data to train the network offline. The network training data of the present invention mainly comes from the temperature change records in simulation model experiments, animal experiments and clinical trials. For example, in high-simulation human model experiments, pig animal experiments and patient clinical trials, researchers collected data on the changes in the temperature of the inner and outer walls of the catheter, nasopharyngeal brain temperature and core body temperature over time at different cooling stages. These data reflect the dynamic changes in temperature when the present invention is used for selective brain cooling: including the drop in brain and whole body temperature in the initial stage of cooling, the time required to reach the target temperature, the temperature fluctuation range in the maintenance stage, and the rate of rewarming after stopping cooling, etc. (see the statistical results in Tables 1 to 3).

[0047] Training samples for the feedforward neural network (MLP) can be constructed by taking state characteristics (such as sensor readings and temperature change rates) at each moment as input and outputting the optimal PID parameter adjustments at that moment. These "optimal PID parameters" can be obtained in a variety of ways, such as extracting them from records of empirically tuned PID controllers (manually adjusting the parameters to achieve optimal performance) or selecting the optimal temperature control results of different PID parameters in a simulation model. This allows for global optimization of PID gains under different scenarios, constructing a corresponding dataset for inputting the optimal PID parameters and using it to train the feedforward neural network (MLP).

[0048] During training, the loss function Defined as the mean square value of the temperature control error, for example, the temperature setting value for the outer wall of the catheter ,use: in For the The outer wall temperature is collected at each moment (or the average value of multiple points is taken). If the inner wall temperature error needs to be considered at the same time, the inner wall temperature deviation term can be weighted and added to the loss function. For example, the comprehensive loss , by choosing the weight While ensuring the accuracy of outer wall temperature control, the inner wall temperature deviates from normal body temperature. 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. The network weights are updated using the backpropagation (BP) algorithm and gradient descent-based optimization. Specifically, iterative training of the network using an adaptive learning rate optimization algorithm, such as the Adam optimizer, can accelerate convergence and avoid getting stuck in local minima. For the training dataset, mini-batch gradient descent is used to divide the sample set into batches (for example, each batch contains 32 time point samples), and training is performed batch by batch to ensure stable updates. The validation set error is monitored to prevent overfitting. If training data is limited, a particle swarm optimization algorithm can be used to globally search for the optimal solution for the network weights, thereby improving the robustness of the training to initial values. In actual training, the initial learning rate can be set, for example, to 0.001. The number of training iterations depends on convergence (typically between 5,000 and 20,000 iterations) to ensure a steady decline in the loss. After sufficient training, the neural network PID controller will show good generalization ability in a wide range of temperature change scenarios, and can output reasonable PID parameter adjustment values ​​regardless of rapid cooling or constant temperature maintenance stages.

[0049] Dynamic control process and execution steps: The neural network optimized PID controller runs throughout the entire cooling intervention process, adjusting the output of the flexible semiconductor cooling plate in real time. Its dynamic control process can be divided into the following continuous cycle steps: Multi-point data acquisition: The MCU (Microcontroller Unit) control module collects the current catheter inner and outer wall temperature data from each temperature and humidity sensor at a set frequency, as well as the patient's core body temperature and brain temperature indicators. It also records the current time and stage (such as the duration of cooling). These data constitute the state feature vector , as mentioned above contains and other information.

[0050] Neural network calculation: The latest feature vector Input neural network parameter regulator. After forward calculation, the network outputs the parameters of the PID controller corresponding to the current state. For example, when it is detected that the outer wall temperature of the catheter is still higher than the target and in the early stage of cooling, the network may output a large To speed up cooling; if the brain temperature is close to the target or the inner wall temperature is low, the network will reduce , prevent overshoot.

[0051] PID control output: MCU will update the Load the PID control algorithm module. The PID controller reads the set target temperature (or the allowed temperature difference range) and calculates the current error. In many cases, the present invention can be used to control the temperature of the outer wall of the conduit. (or error based on the temperature difference between the inside and outside of the pipe). Then, the PID formula (3) calculates the control signal ——That is, the voltage value that needs to be applied to both ends of the cooling plate.

[0052] Drive actuator: Control signal The output of the MCU is applied to the corresponding flexible semiconductor refrigeration sheet through the power drive circuit. Since the present invention has multiple refrigeration sheet partitions, the MCU can perform the above control calculations for different partitions. In other words, each area has its own temperature feedback and control output. , thereby achieving independent regulation of each zone and coordinated control of the entire system. For example, if the outer wall temperature of the middle section of the duct is slightly above the target but the temperature at both ends has reached the target, the MCU can increase the voltage of only the middle section of the cooling plate, while maintaining the voltage in other areas unchanged, thereby reducing temperature unevenness.

[0053] Feedback and loop: The flexible semiconductor refrigeration chip receives voltage The cooling / heating power is then instantly changed, causing the catheter temperature to change. The temperature and humidity sensor detects the new temperature value and feeds it back to the controller. The system then enters the next control cycle, returning to step 1 and looping continuously. 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 always stably maintained near the target range. When the cooling treatment needs to end, the control system gradually reduces the cooling chip voltage according to the preset rewarming curve, gently raising the catheter outer wall temperature to near body temperature, avoiding rebound overheating caused by abrupt cooling.

[0054] This control process implements an adaptive temperature control closed loop: a neural network rapidly "senses" the current state and adjusts the PID gains, ultimately applying precise control via the PID algorithm. This ensures a smooth transition in catheter temperature across various dynamic conditions (e.g., initial cooling, maintenance, and rewarming). This not only meets the requirements for selective brain cooling, requiring a low outer wall temperature, but also prevents drastic changes in the inner wall and the patient's core temperature.

[0055] like Figure 2As shown, a power module controls the current and voltage of the flexible semiconductor cooling sheet 2, a DC-DC converter adjusts the output voltage, and a power MOSFET adjusts the output current via a PWM (pulse width modulation) signal. The DC-DC converter is connected to the MUC, and the MCU control module is isolated from the MOSFET via an optocoupler before being connected. Multiple power module MOSFETs and multiple DC-DC converters are used, with each flexible semiconductor cooling sheet 2 connected to a MOSFET and a DC-DC converter. Each MOSFET and DC-DC converter is independently controlled by the MCU control module. After the MCU control module sets the temperature, it automatically adjusts the voltage across the flexible semiconductor cooling sheet 2 in different areas, achieving precise and stable temperature regulation, providing more accurate conditions for clinical treatment.

[0056] The MCU control module collects data from each temperature and humidity sensor 3 in a specific order. If multiple temperature and humidity sensors 3 are connected to the MCU control module, the MCU control module first sends a data read command to the first temperature and humidity sensor. After data reception and processing are complete, the MCU control module performs the same operation on the second temperature and humidity sensor, and so on, periodically collecting data from each temperature and humidity sensor. The MCU control module's timer function is used to set fixed time intervals for collecting data from each sensor, ensuring periodic and consistent data collection and enabling the acquisition of temperature and humidity parameters at each section within the endotracheal tube 1.

[0057] In order to achieve precise control of the flexible semiconductor refrigeration sheet 2, a current acquisition circuit and a voltage acquisition circuit are used to monitor the actual current and voltage output to the flexible semiconductor refrigeration sheet 2, and feed back to the MCU control module to achieve closed-loop control; the current sampling uses the INA180A2IDBVR current detection amplifier to collect the output current, and the voltage divider resistor is used to sample the input (output) voltage.

[0058] The MCU control module is also equipped with a display module. The MCU controls the collected temperature and humidity data, filters it, and calibrates it. It then uses a coordinate mapping algorithm to plot a curve, mapping the collected temperature and humidity data to the display module's coordinate system. The display module uses a liquid crystal display (LCD) or an organic light-emitting diode (OLED) display. Programming enables the collection, processing, and plotting of temperature and humidity data, and displays the temperature and humidity curve on the OLED display. The MCU controls the collected current and voltage data from each flexible semiconductor cooling plate 2. Using its built-in ADC (analog-to-digital converter) module, the module converts the analog voltage signals into digital signals, thereby collecting the voltage and current data. Using a preset algorithm, the collected voltage and current data are converted into coordinate values, plotted, and displayed on the OLED display. The MCU control module is connected to a storage device that stores the collected voltage, current, and temperature and humidity data for subsequent review and analysis.

[0059] like Figure 4 The following graphs show the experimental results of the multi-point temperature control experiment using the present invention. The settings interface on the left displays the inner wall temperature setpoint of 28.5°C and the outer wall temperature setpoint of 20.5°C. In the six graphs on the right, the blue curve represents the temperatures of the three outer wall sensors, the red curve represents the temperatures of the three inner wall sensors, and the black dashed line represents the target value. As can be seen, under intelligent control, the temperatures at each measuring point steadily approached their target temperatures, and the temperature difference between the inner and outer walls remained within a safe range. The present invention enables the multi-point temperatures on the outer and inner walls of the catheter to converge quickly and remain stable to the target values. The readings of the three outer wall sensors (blue curve) gradually decrease from an initial level of approximately 25°C, approaching the set level of 20°C in approximately 60 seconds. The inner wall temperature (red curve) rises from approximately 30°C and stabilizes at nearly 29°C (slightly below the set level of 30°C, simulating the human inner wall temperature of 37°C). Throughout this process, the curves transition smoothly, with no noticeable oscillation or overshoot. This demonstrates that the neural network-optimized PID control effectively suppresses temperature overshoot and keeps the steady-state error within a very small range. Notably, the temperatures at different locations on the outer wall are nearly identical, and the temperature differences between points on the inner wall are minimal, demonstrating a very uniform temperature distribution along the catheter wall. In contrast, using uniform, fixed PID parameters can lead to temperature deviations at certain locations, or undershoot / overshoot near the target. However, the present invention enables coordinated operation of various regions, quickly responding to local deviations and ensuring a balanced and stable temperature field distribution.

[0060] Further comparative experiments showed that the neural network PID controller outperformed the traditional PID in terms of dynamic response and steady-state accuracy. In the initial stage of cooling, the network-optimized controller can provide greater driving force than the fixed PID, increasing the rate of temperature drop on the outer wall of the catheter by about 15%, thereby reaching the low temperature range required for treatment more quickly. When approaching the target temperature, the traditional PID often has a certain overshoot due to fixed parameters (the outer wall temperature of the catheter is temporarily lower than the target, for example, by more than 2°C, and then rises again); in contrast, the neural network adjusts the error trend in a timely manner. and , keeping overshoot to within 0.5°C and shortening stabilization time. For example, under the same test conditions, the intelligent controller reduced the time required to stabilize the outer wall temperature within the target range (±0.2°C) by approximately 20%, achieving negligible steady-state error. The inner wall temperature of the duct remained constant at approximately 37°C, with only a slight increase during the initial cooling phase before being brought back to a steady state. This demonstrates that the algorithm can achieve both outer wall cooling and inner wall temperature stability.

[0061] More importantly, the improved temperature control precision has led to significant improvements in clinical outcomes. In animal experiments, selective cooling using this invention resulted in a one-hour drop in pig brain temperature by an average of approximately 4.1°C, while core body temperature only decreased by approximately 0.9°C. Preliminary clinical trials showed that the average nasopharyngeal temperature of patients decreased from 37.5°C to approximately 34.2°C, while 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 whole-body temperature decreased by approximately 1.8°C). Throughout the cooling process, due to stable temperature control, the patients experienced no noticeable chills, and vital signs such as blood pressure and heart rate remained stable. During the rewarming phase, the control system slowly warmed the patient at a rate of approximately 1°C per hour, successfully avoiding complications such as rebound temperature or hypotension that could be caused by rapid rewarming. Furthermore, examination of the tracheal mucosa revealed no localized damage due to hypothermia—a finding strongly associated with the strict and uniform temperature control of the catheter's outer wall, which was within a safe range and free of cold spots.

[0062] The above experimental results verify the effectiveness and safety of the temperature control system of the present invention. The neural network-optimized PID control not only achieves a faster and smoother temperature response, but also ensures the efficacy and safety range of selective brain cooling. As can be seen from the temperature curve, the brain cooling amplitude is significantly better than the whole-body cooling amplitude (more than doubled), which is of great significance for clinical scenarios such as post-cardiopulmonary resuscitation brain protection and stroke emergency treatment that require rapid brain cooling. At the same time, stable temperature control avoids the common side effects of traditional whole-body cooling, providing patients with a gentler treatment experience.

[0063] The present invention combines a tracheal tube device with precise positioning using a rotating permanent magnet and optimized temperature control using a neural network to achieve selective hypothermia protection for the patient's brain. The temperature control algorithm described in the present invention utilizes an innovative structure combining a feedforward neural network and PID control, which can adaptively adjust the cooling output based on real-time feedback, ensuring that the temperature of the inner and outer walls of the tube remains within the ideal range. Compared to traditional fixed-parameter control methods, this intelligent control system significantly improves both dynamic performance and steady-state accuracy: faster temperature response, smaller overshoot oscillations, and more uniform spatial distribution, ensuring a cooling effect while minimizing disturbances to normal physiology.

[0064] Results from animal and clinical trials have preliminarily confirmed its clinical value: by precisely controlling the outer wall of the catheter to maintain a low temperature, this method can significantly reduce brain temperature within a short period of time without causing serious systemic side effects, thereby reducing the incidence and progression of brain damage. The constant temperature of the inner wall ensures airway safety and patient comfort, avoiding tracheal mucosal damage or respiratory complications that can result from traditional cooling methods. This selective brain cooling technology has the potential to be applied in emergency treatments requiring reduced brain metabolism, such as post-cardiac arrest resuscitation, severe craniocerebral injury, and stroke, thereby improving patients' neurological outcomes.

[0065] This invention utilizes a multi-point temperature control system to precisely regulate the internal and external surface temperatures of an endotracheal tube. The flexible endotracheal tube is embedded with several flexible semiconductor cooling chips and temperature and humidity sensors along its length. Each flexible semiconductor cooling chip (based on the Peltier effect) has one end near the outer tube wall for localized cooling and the other end near the inner tube wall for heating incoming airways. This creates a low-temperature environment on the outer tube wall, selectively lowering brain temperature while maintaining the inner tube wall near normal body temperature to protect the airway. Temperature and humidity sensors are located near each cooling chip, collecting real-time temperature data from multiple points inside and outside the tube. The control system, based on a microcontroller (MCU), dynamically adjusts the voltage output of each flexible semiconductor cooling chip based on sensor-generated information such as the internal and external tube temperatures, 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 tube wall while stably controlling the outer tube wall within a safe range of 18–21°C, achieving precise localized cooling and preventing overheating or overcooling.

[0066] Since the patient's body temperature and environmental conditions will change dynamically during the operation, the temperature control system is required to have fast response and adaptive capabilities. On the one hand, it is necessary to ensure that the cooling process is smooth and controllable to avoid the outer wall temperature of the catheter being too low and causing cold damage to local tissues; on the other hand, it is necessary to ensure that the temperature of the inner wall of the catheter is constant to prevent cold air from stimulating or lowering the body temperature. To this end, the present invention designs a closed-loop feedback control architecture: the sensor provides real-time temperature feedback, and the control algorithm calculates the optimal driving voltage of the cooling plate according to the error between the set target temperature and the actual temperature, and corrects the temperature deviation by adjusting the cooling / heating power of the cooling plate. The basic control adopts the classic PID controller framework to achieve automatic temperature adjustment. On this basis, a feedforward neural network is introduced to adaptively optimize and adjust the PID parameters, so that the system can adaptively adjust the control force according to different stages and environmental changes, thereby significantly improving the stability and accuracy of temperature control.

[0067] like Figure 2 As shown, the temperature and humidity control system is also connected to an alarm module. During the process of delivering gas to the patient, the temperature and humidity sensor 3 performs dynamic monitoring. If it is found that the current temperature and humidity of the transmitted gas do not meet the requirements and exceed the threshold value pre-examined by the MCU control module or the patient has an abnormally high temperature, the alarm module will be used to remind the patient and provide effective intraoperative care. The alarm module is a buzzer, LED light, vibration motor, sound and light alarm or sound and light alarm; when it is detected that 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, and reminds medical staff through LEDs of different colors or flashing frequencies. The vibration motor reminds through the vibration motor, or the sound and light alarm sends a strong sound and light alarm signal; or the voice module broadcasts a pre-recorded voice to remind.

[0068] The rotating permanent magnet positioning system includes an external magnetic field generating device, an endotracheal tube assembly, and a control module. The external magnetic field generating device includes a permanent magnet and a permanent magnet drive mechanism. The permanent magnet is preferably made of high-performance neodymium iron boron material (such as N52 grade), with a magnetic field strength range of 0 to 300 mT (millitesla), more preferably 100 to 200 mT. The magnet rotation frequency is 0 to 5 Hz, which can achieve dynamic magnetic field adjustment. The magnetic field gradient generated by the permanent magnet in the near field region can reach up to about 5 mT / mm, thereby providing sufficient magnetic field force for traction guidance, such as Figure 7 As shown, 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 magnets to rotate and adjust the magnetic field direction. The three-axis drive mechanism's drive motor is preferably a brushless DC motor equipped with an encoder for precise angle control. It has a rated power of approximately 50 W and a no-load speed of up to 3000 rpm. All materials other than the permanent magnets are made of non-magnetic materials (such as brass alloy or engineering plastics) to ensure that the magnets' rotation is not subject to magnetic interference and that the magnetic field direction can be adjusted with an accuracy of within 1°.

[0069] like Figure 6 As shown, the permanent magnet three-axis drive mechanism includes permanent magnet 6, the core component for generating a magnetic field, which forms a specific magnetic field through its own magnetic properties. A permanent magnet drive motor 8 is mounted on an inner ring 9 and connected to permanent magnet 6. It directly drives the permanent magnet to rotate, changing the direction and angle of its magnetic field. Permanent magnet 6 and permanent magnet drive motor 8 are mounted within inner ring 9 and can rotate within a certain range, providing support and preliminary adjustment of the permanent magnet's angle. An inner ring drive motor 10 is connected to inner ring 9 and is responsible for driving the inner ring to rotate relative to outer ring 12, further adjusting the spatial angle of the permanent magnet and the inner ring as a whole. An inner ring position encoder 11 monitors the rotational position and angle of inner ring 9 in real time, providing feedback to the control system for precise control of inner ring rotation. Outer ring 12 serves as the external support structure for inner ring 9 and its internal components and can also rotate itself, providing an additional dimension of adjustment. An outer ring drive motor 13 is connected to outer ring 12 and drives the outer ring to rotate, enabling adjustment of the entire inner ring and permanent magnet assembly over a wider range of spatial angles. The outer ring position encoder 14 monitors the rotational position and angle of the outer ring 12 and provides feedback to the control system, enabling precise control of the outer ring's rotation. The outer casing 15 protects the entire three-axis drive mechanism, shielding internal components from dust and interference, while also providing a mounting base for the various internal components. When energized, the permanent magnet drive motor 8 outputs torque according to control commands, driving the permanent magnet 6 to rotate about its axis. By varying parameters such as the motor's speed and direction of rotation, the permanent magnet's rotation angle and speed 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 real-time position information of the inner ring and feeds it back to the control system. Based on the deviation between this feedback information and the target angle, the control system adjusts the operating state of the inner ring drive motor to ensure precise rotation of the inner ring to the specified angle, thereby changing the spatial angle of the permanent magnet in one dimension. The outer ring drive motor 13 operates according to the control system's commands, driving the outer ring 12 to rotate, thereby spatially adjusting the angle of the inner ring and permanent magnet assembly as a whole. The outer ring position encoder 14 continuously monitors the outer ring's rotation angle and feeds this data back to the control system. Based on the difference between the feedback value and the preset value, the control system adjusts the outer ring drive motor in real time to ensure accurate rotation of the outer ring, thus adjusting the spatial angle of the permanent magnet in another dimension.

[0070] Through the coordination of the three movements of the permanent magnet's own rotation, the inner ring's rotation, and the outer ring's rotation, the spatial position and angle of the permanent magnet can be adjusted in all directions and precisely in three-dimensional space, and then the direction, intensity distribution and other characteristics of the magnetic field it generates can be flexibly adjusted to meet the specific requirements of the magnetic field in different application scenarios.

[0071] like Figure 1 As shown, the endotracheal tube assembly includes a magnetic guide element 5 and a magnetic sensor 4, positioned at the distal end of the endotracheal tube 1. The magnetic guide element, for example, is a small cylindrical permanent magnet (preferably made of neodymium iron boron) with a diameter of approximately 3 mm and a length of 10-15 mm. It is fixed to the distal end of the tube and is used to generate a guiding force under the influence of an external magnetic field. The magnetic sensor 4 is positioned adjacent to the magnetic guide element and is used to detect the strength and direction of the external magnetic field and provide a feedback signal. This magnetic sensor is preferably a Hall effect magnetic field sensor (such as the Allegro A1324 linear Hall effect sensor), with an effective detection range of up to 100 mm and a sensitivity of approximately 0.05 V / T (volt 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 within the tube via a support structure and secured with a medical-grade adhesive to ensure stable positioning and waterproof safety during intubation.

[0072] The control module comprises a signal processing unit and an execution unit, with a microcontroller at its core for closed-loop control. The microcontroller is preferably a 32-bit ARM Cortex-M series microcontroller (such as the STM32 series). Its built-in analog-to-digital converter (ADC) acquires analog signals from the magnetic sensor and controls the motor of the permanent magnet's three-axis drive mechanism via PWM signals, thereby adjusting the permanent magnet's rotation angle. A software algorithm embedded in 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. Fuzzy control or adaptive control strategies can also be combined to dynamically adjust PID parameters to improve the system's adaptability to anatomical differences among different patients. If necessary, a neural network control model can be incorporated, leveraging trained nonlinear models to improve control accuracy and robustness in complex environments. Through this control module, the system can adjust the intensity and direction of the external magnetic field in real time, precisely controlling the position and angle of the magnetic guide element at the distal end of the endotracheal tube, thereby achieving accurate positioning of the tube.

[0073] In the specific implementation process, the manufacturing and assembly steps of the rotary permanent magnet positioning system include: (1) Assembly of the magnetic field generating device: The permanent magnet is fixed to the permanent magnet three-axis drive mechanism, and the magnet installation is adjusted so that its magnetic pole direction can ensure that the magnetic field direction can be accurately changed as designed during rotation, ensuring a firm structure and avoiding interference between magnetic components.

[0074] (2) Magnetic sensor calibration: After assembling the magnetic sensor, perform a zero-point calibration (record the baseline value of the sensor output when there is no magnetic field) in the absence of external magnetic field interference. Then, measure the sensor output under a known magnetic field strength to calculate the actual sensitivity (V / T) and adjust the amplifier gain accordingly. Multi-point calibration establishes the corresponding relationship between sensor output and magnetic induction intensity to ensure that the linearity and accuracy of the magnetic sensor measurement meet the requirements.

[0075] (3) Fixing the catheter assembly: The calibrated micro-magnetic sensor is fixed in the inner cavity of the distal end of the endotracheal tube so that it is adjacent to the magnetic guidance element. The sensor and its leads are encapsulated and sealed with a medical biocompatible adhesive to prevent them from being intruded by liquids or affected by mechanical vibrations during disinfection and intubation. The magnetic guidance element (a small permanent magnet) is embedded and fixed in a predetermined position at the distal end of the catheter so that it is positioned relative to the magnetic sensor to ensure that the distal end of the catheter can be deflected in the desired direction when subjected to an external magnetic field, thereby achieving magnetic navigation-assisted intubation.

[0076] like Figure 1 , Figure 4 and Figure 5 As shown, a control method for a rotating permanent magnet positioning system includes the following steps: (1) Magnetic field model establishment and parameter calibration: A magnetic field model generated by a rotating permanent magnet is established to calculate the magnetic field intensity and gradient at the distal end of the catheter. According to 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 by formula, for example, on the axis in is the vacuum permeability, is the magnitude of the magnetic moment, and are the radius and length of the magnet respectively, is the axial distance from the center of the magnet. The partial derivative of the above magnetic field formula with respect to the spatial coordinates can be obtained to obtain 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 guide element can be calculated , approximately satisfies ,in is the magnetic moment vector of the magnetic guide element at the distal end of the catheter, is the external magnetic field strength vector. Experimental calibration is used to obtain model parameters (such as the equivalent magnetic moment of a magnet) and calibrate the correspondence between the magnetic sensor reading and the actual magnetic field to ensure that the control system accurately and reliably senses the magnetic field strength.

[0077] (2) Intubation path planning: Before intubation, the optimal path of the tracheal tube from the entrance to the target position in the trachea is planned. A third-order Bezier curve is used to fit and optimize the intubation path. The path is determined by the starting point, the end point, and two control points. The parametric equation of the Bezier curve is: in is the starting position of the catheter, is the tracheal target location, and The intermediate control points are used to adjust the shape and curvature of the path. 、 The position of the Bezier curve is determined by the position of the catheter, generating a smooth, continuous curved path that avoids anatomical obstacles, allowing the distal end of the catheter to enter the trachea along this path. The trajectory planning process considers anatomical constraints (such as avoiding contact with the esophageal wall and vocal cords) to ensure that the resulting Bezier curve path is feasible and safe for actual intubation.

[0078] (3) Closed-loop control execution: During the intubation process, the control module implements closed-loop regulation of the external magnetic field. According to the planned path, the target position (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 expected value to obtain the error. The control module uses the PID algorithm to dynamically adjust the rotation angle of the magnet according to the error, and its control output satisfies: in 、 、 are the proportional, integral, and differential coefficients of the PID controller. By appropriately adjusting the 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 to adaptively adjust the PID parameters according to the error size and rate of change. In the presence of model uncertainty or external interference, an adaptive control algorithm can be used to correct the control parameters online. In addition, a neural network-based control model can be combined to use the trained nonlinear mapping relationship to predict and correct the magnetic field control quantity to improve the accuracy of catheter positioning control in complex environments. Through the above closed-loop control, it is ensured that the magnetic guide element at the distal end of the catheter can be advanced and positioned strictly along the planned path.

[0079] (4) Intubation guidance and positioning: During the actual intubation operation, the operator gradually inserts the tracheal tube into the patient's airway along the planned path, and 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 area, the control system continuously corrects the direction of the magnetic field based on the feedback from the magnetic sensor, guiding the distal end of the tube toward the tracheal entrance. The tube advances along a predetermined Bezier curve path. When the magnetic sensor detects that the distal end of the tube has reached the target position (for example, when the magnetic field intensity reaches a preset threshold or the positioning error converges to an allowable range), the control module stabilizes the magnetic field to maintain the position of the tube. The external magnetic field generating device is then removed, and the tracheal tube is fixed at a predetermined position in the patient's airway to complete the intubation positioning. Through the above control method, precise control of the tracheal tube insertion path and posture can be achieved, thereby improving the success rate and safety of tracheal intubation operations, such as Figure 5 shown.

[0080] like Figure 11 As shown in FIG, the process of preparing a flexible semiconductor refrigeration sheet on a flexible endotracheal tube is as follows: S1, substrate preparation and cleaning: A flexible endotracheal tube is selected as the substrate. The tube is made of a medical-grade, soft and gentle material, such as silicone or polyurethane, with a diameter of, for example, 5 to 10 mm. Remove dust, grease and other impurities from the surface of the tube: first rinse with a neutral detergent and deionized water, then place it in an ultrasonic cleaning tank and wash with ethanol and deionized water for 5 to 10 minutes respectively to remove organic matter and particles attached to the surface. During the cleaning process, the liquid temperature is controlled at 25 to 40°C to improve the cleaning effect. After cleaning, use pure nitrogen to blow dry the inner and outer surfaces of the tube, and place the tube in a clean oven and dry it at 50°C for 10 to 30 minutes to ensure that the surface of the tube is dry, clean and free of residue, providing a clean substrate surface for subsequent processes; S2, surface activation pretreatment: The surface of the catheter after cleaning and drying in step S1 is activated to improve the adhesion and uniformity of the film. Preferably, a plasma surface treatment method is used, such as introducing oxygen into a vacuum plasma cleaning machine, maintaining the pressure at ≤100 Pa, applying a radio frequency power of 50 to 200 W, and plasma treatment for 1 to 5 minutes to cause micro-roughening of the catheter surface and increase the surface energy. This step can remove residual organic matter on the catheter surface and introduce polar functional groups, thereby enhancing the adhesion of subsequent deposited layers. Optionally or auxiliary, immediately after the plasma treatment, a layer of silane coupling agent primer (such as 3-aminopropyltriethoxysilane APTES alcohol solution, concentration 1% to 5%) is coated on the catheter surface, allowed to stand for 5 to 10 minutes to allow it to self-assemble into a film, and then baked at 100°C for 10 minutes to cure the coupling agent. After the above activation pretreatment, the catheter surface has good wettability and activity, which can ensure that the film layer in the subsequent coating process is firmly bonded and evenly distributed; S3, Depositing the Bottom Electrode Layer: Depositing a flexible bottom electrode conductive layer on the outer surface of the pretreated inner wall of the conduit, which serves as the lower electrode of the semiconductor cooler. Magnetron sputtering is preferably used to deposit the metal film: The conduit is fixed on a rotatable base to ensure uniform deposition, placed in a vacuum sputtering chamber, and evacuated to a substrate vacuum of no more than 5×10^−4 Pa. A two-layer metal deposition is used to improve adhesion and conductivity: First, an adhesion layer metal such as titanium (Ti) or chromium (Cr) is sputtered to a thickness of approximately 10 to 100 nm, with a sputtering power of, for example, 50 W, an argon operating pressure of approximately 0.5 Pa, and a deposition rate of approximately 0.1 nm / s; then, a primary conductive metal layer such as gold (Au) or copper (Cu) is sputtered thereon. When Au is selected, the sputtering power is, for example, 100 to 200 W, the argon pressure is 0.5 to 1 Pa, the deposition rate is about 1 to 5 nm / s, and the deposition thickness is preferably in the range of 1 to 5 μm; when Cu is selected, a thin layer of Au (for example, 0.1 to 0.5 μm thick) can be sputtered after sputtering a Cu layer with a thickness of about 1 to 3 μm for anti-oxidation protection. During the deposition process, the film thickness is monitored in real time by a quartz crystal monitor, and the deposition is stopped when the predetermined thickness is reached. The bottom electrode metal layer should be uniform, continuous, and firmly attached without peeling or cracking. If necessary, the deposited catheter can be placed in an inert atmosphere (such as nitrogen) for heat treatment at 80 to 120°C for 30 to 60 minutes to release the stress in the film and improve the bonding strength and stability of the metal film; 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 the subsequent deposition of N-type and P-type semiconductors. This step can be performed using a photoresist mask in conjunction with wet etching or laser scribing. A preferred method involves uniformly coating the surface of the catheter metal layer with a layer of photoresist (e.g., a negative photoresist with a thickness of 10-20 μm). This is ensured by a flexible lamination tool, and then rotating the catheter using a dedicated fixture to expose the pre-designed patterned area (including at least two isolated electrode regions). After development, the metal regions not protected by the photoresist are selectively etched using an appropriate etchant, such as potassium iodide solution for the Au layer and ferric chloride solution for the Cu layer. The etching temperature is maintained at 25-40°C for 1-5 minutes until the catheter substrate is exposed, forming the desired electrode pattern. The size of each electrode region depends on the design of the cooling plate and is typically rectangular or annular, with a spacing of, for example, 0.5-1 mm to ensure isolation and separation of the electrodes. After etching is complete, the catheter is thoroughly cleaned with deionized water to remove corrosion byproducts and rinsed with anhydrous ethanol to prevent residual moisture. The catheter is then blown dry and heated to 50-60°C for 5 minutes. Finally, the photoresist mask is removed (using acetone ultrasonic cleaning for 2-5 minutes), resulting in mutually insulated metal bottom electrode regions (referred to as the first and second region electrodes, respectively), with a clean surface free of residue. S5, N-type semiconductor deposition mask setting: Before depositing N-type thermoelectric material on the catheter, use a mask to cover the undeposited area to ensure that the N-type material is only deposited on the designated electrode area. Place the customized flexible metal mask template close to the surface of the catheter so that the second zone electrode and its surrounding area are covered by the mask, and only the deposition window corresponding to the first zone electrode is exposed. The mask should be firmly fixed and accurately positioned, aligned with the first zone electrode area and slightly larger than the electrode area to ensure complete coverage of the electrode. It is preferred that the mask fits tightly to the surface of the substrate to prevent the material from leaking under the mask during deposition. For cylindrical catheters, a semicircular opening mask can be used and locked with a mechanical clamp to achieve surround shielding of the target electrode area. After the mask is set, check that the unblocked area is only the target electrode, and there are no other exposed parts, and then proceed with the deposition process; S6, Deposition of N-type Semiconductor Refrigeration Material Layer: Deposit an N-type semiconductor thermoelectric material thin film on the first electrode region exposed by the mask. Magnetron sputtering is preferably used to deposit a Bi2Te3-based alloy thin film as the N-type thermoelectric material. The guide tube is mounted on a rotatable fixture within the sputtering apparatus, the mask is adjusted to maintain a fixed position, and the substrate is evacuated to a vacuum level no higher than 1×10^−3 Pa. A high-purity N-type Bi2Te3 target is selected (optionally doped with Se to enhance N-type conductivity). High-purity argon gas is introduced to a working pressure of 0.2-0.5 Pa. Deposition is performed using RF sputtering at a power of 100-300 W. To improve film crystal quality, the substrate temperature is maintained at 50-100°C during sputtering (this temperature is still acceptable for the guide tube material and does not deform). Deposition time is determined based on the target thickness. Based on a deposition rate of approximately 0.5-2 nm / s, a deposition time of approximately 0.7-2.8 hours is required to achieve a thickness of, for example, 5 μm. The preferred deposition thickness is 5 to 15 μm to take into account both device flexibility and cooling performance. If the full thickness cannot be deposited in one go, multi-stage deposition can be used. After depositing 1 to 2 μm in each stage, pause to cool the tube to room temperature before continuing to the next stage until the total thickness requirement is reached. During the deposition process, a crystal oscillator is used to monitor or a monitoring piece placed near the tube is used to measure the thickness growth to ensure that the thickness is within the specified range and the composition is close to the stoichiometric ratio. After deposition is completed, the sample can be placed in a vacuum or nitrogen atmosphere and annealed at 100 to 150°C for 30 to 60 minutes (the upper limit is selected based on the temperature tolerance of the tube material) to promote the crystallization of the Bi2Te3 film and improve its thermoelectric properties. After annealing, slowly cool to room temperature to avoid cracking of the film due to thermal shock. The resulting N-type semiconductor film should be uniform and dense, with a thickness of about 5 μm (the allowable range is 5±1 μm or according to design requirements), good bonding with the bottom first zone electrode, and complete coverage without defects; S7, remove the N-type deposition mask: After the N-type semiconductor material deposition is completed and cooled, carefully remove the mask used in step S5 from the surface of the catheter. Release the mechanical clamp and remove the metal mask to avoid applying shear stress to the newly deposited N-type film. If there is a small amount of deposition material debris attached to the back of the mask, use a soft brush or dust-free cloth to gently clean the surface of the catheter to ensure that the second zone electrode area remains clean and exposed. Check the N-type film pattern: it should only be deposited on the first zone electrode, with neat edges and no excess deposits extending to non-target areas. If individual splashing particles are found to fall into other areas, they can be gently removed under a microscope with a fine-pointed blade, or removed with tape. Afterwards, wipe the surface of the catheter with an anhydrous ethanol cotton swab to remove any possible dust, blow dry and set aside. At this point, the first zone electrode is covered with an N-type semiconductor layer, while the second zone electrode is still exposed, and the next step of depositing P-type material can be carried out; S8, P-type semiconductor deposition mask setup: Similar to step S5, before depositing the P-type thermoelectric material, shield the conduit to ensure that the P-type material is deposited only in the second zone electrode area. Reposition the cleaned mask so that its opening is aligned with the second zone electrode area and covers the rest of the area, including the first zone electrode. Secure the mask to ensure it does not shift during the deposition process. Reconfirm that only the second zone electrode area is exposed in the mask window, with no other conduit parts exposed, and then proceed with the P-type material deposition process. S9, Deposition of P-type semiconductor refrigeration material layer: Deposit a P-type semiconductor thermoelectric material thin film on the second electrode region exposed by the mask. A magnetron sputtering process similar to that used for 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 catheter in the sputtering chamber again, maintaining the substrate vacuum below 1×10^−3Pa. Introduce high-purity argon gas to a working pressure of approximately 0.3Pa, and set the RF sputtering power to 100-300W. If the catheter substrate permits, the substrate can be heated to 50-100°C to improve film quality (if the N-type film has already been deposited, the P-type deposition temperature should be controlled not to exceed the previous annealing temperature to avoid affecting the properties of the N-type layer, such as controlling it at around 100°C). The deposition process also uses staged or low-speed deposition to achieve the desired thickness (e.g., 5-15μm, equivalent to the N-type layer) and ensure accurate composition. By controlling the ratio of Bi to Sb and the sputtering rate, the stoichiometric ratio and doping concentration of the P-type film are ensured to meet the design requirements, resulting in a 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 in an inert atmosphere for 30 minutes helps eliminate stress within the film and increase the grain size, thereby reducing interface scattering and increasing the thermoelectric figure of merit. After cooling to room temperature, a P-type semiconductor film covering the second zone electrode is obtained. Its thickness is approximately 5μm (controlled within ±1μm according to the design tolerance), the surface is flat, and it is firmly bonded to the bottom electrode. S10, remove the P-type deposition mask: After the P-type material deposition is completed and cooled, remove the mask used in step S8. Loosen the fixing device and remove the mask to avoid scratching the surface of the newly deposited P-type film. Inspect and clean the surface of the catheter: Confirm that the P-type film is strictly limited to the electrode area of ​​the second zone and is not connected to the N-type film in the first zone or short-circuit bridge. If a very small amount of P-type material is found to be sputtered to the edge of the N-type area due to the mask gap, it should be removed using a fine mechanical method to ensure that the two semiconductor areas are completely electrically isolated. After cleaning, blow off the 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 surface of the catheter, respectively attached to two adjacent but insulated metal bottom electrodes; S11, preparation of the top electrode connection layer: forming a top electrode conductive connection above the N-type and P-type semiconductor elements to form a series connection of the thermoelectric circuit. First, clean the surface of the N-type and P-type elements to ensure that they are free of oxides and dirt, and they can be lightly plasma bombarded for a few seconds to improve the reliability of the metal contact. Then, a mask or screen printing method is used to lead out a conductive bridging area between the N-type and P-type elements. For example, a customized opening 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, thereby connecting the two. The mask is accurately positioned and fixed on the conduit, and the top connection metal layer is deposited by magnetron sputtering. It is preferred to deposit a metal with high conductivity and good ductility, such as gold (Au) or silver (Ag). A thin layer of titanium (Ti) or chromium (Cr) (approximately 20 nm thick) is first sputtered as an adhesion layer to improve the bonding between the metal and the thermoelectric material surface. Au is then sputtered, for example, to a thickness of 1 to 3 μm at a deposition rate of approximately 2 to 5 nm / s, under an argon pressure of 0.5 Pa and a sputtering power of 100 W, until a continuous metal bridge layer is formed at the mask opening. This top electrode layer spans the top surfaces of the N-type and P-type elements, each covering a certain area (e.g., 50 to 100% of the thermoelectric element's top area to reduce contact resistance), and forms a bridge between the two in the mask opening, thereby electrically connecting the two thermoelectric elements in series. After deposition, the mask is removed, resulting in 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 via their respective bottom electrodes, thus forming a complete thermoelectric cooling circuit. Care should be taken to ensure that the top electrode metal does not directly contact the bottom electrode to short-circuit. In actual fabrication, precise control of mask position and bridge width (e.g., approximately 0.5mm) is employed to ensure that the bridge metal only connects the tops of the two semiconductor elements. After the top electrode is formed, the resistance between the two bottom electrodes can be measured to initially verify proper electrical connection (the total resistance of the N-type and P-type series connections should be measured). S12, lead-out terminal connection: In order to facilitate the subsequent integration of the cooling plate into the power supply circuit, it is necessary to connect wires to the bottom electrode area as electrical lead-out terminals. Fix thin-diameter wires (such as tinned copper wires with a diameter of 0.1 mm) to the bottom electrodes of the first and second zones respectively. Preferably, a conductive adhesive bonding method is used: apply an appropriate amount of silver paste conductive adhesive (epoxy silver adhesive with high solid content and excellent conductivity) on the surface of each bottom electrode pad, press the stripped wire end onto it, and then heat it at 60-80°C for 30-60 minutes to cure the conductive adhesive. After curing, the wire should be firmly adhered to the electrode and the contact resistance should be extremely low. Low-temperature brazing methods (for example, using low-melting-point solder with a melting point of ≤150°C) can also be used to achieve wire connection under the premise of ensuring that the catheter is not damaged by heat. Regardless of the method used, after the lead connection is completed, use a multimeter to test the path resistance between the wire and the corresponding bottom electrode and the insulation between the two wires to ensure that the lead-out terminal connection is reliable and well insulated from each other; S13, Encapsulation and Protection: Surface encapsulation of the cooling element components is performed to enhance mechanical strength and environmental stability, meeting biocompatibility requirements for medical use. A flexible protective material is applied to the N-type and P-type thermoelectric elements and connecting electrodes on the outer surface of the catheter. The protective layer should be electrically insulating, moisture-resistant, and conformable, such as medical silicone rubber, epoxy resin, or Parylene film. Parylene C chemical vapor deposition is preferred: the entire catheter is placed in a Parylene deposition apparatus, where the dimer is vaporized and polymerized in a vacuum at room temperature to form a uniformly coated polymer film. The encapsulation layer thickness is controlled between 10 and 30 μm to fully cover all components and wire solder joints, forming 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 protective coating can be evenly applied to the catheter by dip-coating or spraying. The coating is then cured at room temperature to 60°C for several hours to solidify the coating. During packaging, care should be taken to avoid blockage within the catheter cavity, and the lead ends of the wires should be left exposed outside the packaging layer for easy electrical connection. After the package is cured, the various layers of the cooling sheet are fixed together, making it difficult for external moisture and mechanical wear to directly contact the internal thermoelectric elements and electrodes, thereby improving the reliability and service life of the device. The final packaged flexible semiconductor cooling sheet is integrated with the catheter surface in appearance, maintaining a certain degree of transparency or translucency for easy observation, without affecting the original softness and bendability of the catheter. S14, Quality Inspection and Performance Testing: The packaged flexible semiconductor cooling element undergoes comprehensive inspection to ensure that product quality meets requirements. First, a visual and structural inspection is performed: Observe the device surface using a microscope to confirm that the encapsulation layer is intact and free of bubbles and cracks, that the film layer is free of peeling, and that the wire connections are secure. After encapsulation, the sensor and cooling element within the catheter are routed along the tube wall and connected through a standard Luer connector or a dedicated electrical connector at the proximal end of the catheter. They are connected to the external MCU control system via a drive cable and powered by an external power supply (DC 12–24 V) or a built-in rechargeable battery pack. Electrical performance testing is then performed: Using a multimeter or a four-probe method, measure the resistance between the two lead wires to verify that it matches the designed value and that the contact resistance is negligible. Further thermoelectric performance is measured by connecting the two lead terminals of the cooling element to an adjustable DC power supply at a constant temperature (e.g., 25°C). A designed current (e.g., 0.1–0.5A) is applied and the current is maintained steady for several minutes. A temperature sensor is placed on the inner surface of the catheter or at the cold end of the cooling element to monitor temperature changes and record the drop in cold end temperature ΔT when current is flowing, relative to the unpowered state. Typically, the cooling element should be able to generate a temperature difference of, for example, 2 to 5°C (depending on the thickness of the thermoelectric material and thermal management conditions), demonstrating its intended cooling function. Furthermore, after a certain period of power application, the power is turned off and the temperature recovery is observed to assess the device's thermal cycling stability. Mechanical performance testing can also be performed, such as repeatedly bending the catheter (with a bend radius of approximately 5 cm, repeated 20 times) and then testing the resistance and cooling performance to ensure device performance remains stable under repeated bending. All tests must comply with relevant medical device standards. If all product indicators meet the requirements after these rigorous tests, the process for fabricating a flexible semiconductor cooling element on a flexible endotracheal tube is complete, and the resulting cooling element device is reliable and meets practical application requirements.

[0081] Clinical application test of selective brain cooling The device of the present invention has been comprehensively tested and validated for conditions requiring brain protection, such as post-cardiopulmonary resuscitation brain protection, acute stroke, and severe brain trauma. The efficacy and safety of the endotracheal tube device for selective brain cooling were evaluated through highly realistic human model experiments, animal experiments, and clinical patient trials. In each experiment, the endotracheal tube with cooling function of the present invention was used for tracheal intubation. A rotating permanent magnetic positioning system facilitated precise placement and positioning of the tube at the appropriate depth in the trachea (the cooling site corresponds to the throat). After successful intubation, the temperature and humidity control system was activated: the outer wall temperature of the endotracheal tube was gradually lowered to approximately 18–20°C (within a controlled range of 17–21°C), while the inner wall of the tube was simultaneously heated to approximately 37°C to ensure that the air entering the airway maintained normal temperature and humidity. Brain temperature (as an indicator of brain temperature) was continuously monitored using a temperature probe placed in the nasopharynx, and core body temperature (as an indicator of whole-body temperature) was monitored using a bladder thermometer. During the cooling intervention, conventional warming measures, such as a warming blanket, were used to maintain trunk temperature to minimize the effects of systemic cooling. After a certain duration of intervention in each group, cooling was gradually discontinued: in the simulation model and animal experiments, cooling lasted 30 to 60 minutes; in the clinical patient group, cooling was maintained for approximately 2 hours, followed by a control system for slowly warming the body at a rate of approximately 1°C per hour until the body temperature approached baseline. Vital signs and potential complications were closely monitored throughout the cooling and rewarming process.

[0082] Highly realistic human body model experiment Five replicated experiments were conducted using a highly realistic patient manikin to simulate the selective cooling of the brain in a clinical emergency setting. Heating elements were built into the manikin's head and torso to maintain initial brain and body temperatures around 37°C. An endotracheal tube (endotracheal tube) was orally inserted into the manikin's airway to the designated location. The cooling device was activated for 30 minutes using the aforementioned parameters. The manikin was then allowed to recover to its initial temperature. Simulated brain temperature (nasopharyngeal sensor temperature) and whole-body temperature (torso sensor temperature) were recorded before and after the intervention. The baseline and lowest temperatures during the intervention, as well as the magnitude of the temperature change, were statistically analyzed. The results are shown in Table 1. As shown in Table 1, the manikin's brain temperature decreased from an average baseline of approximately 37.0°C to a minimum of approximately 34.0°C, a decrease of approximately 3°C. During the same period, the manikin's whole-body temperature only decreased from 37.3°C to approximately 35.5°C, a decrease of approximately 1.8°C. The magnitude of the decrease in brain temperature was significantly greater than that in whole-body temperature, with the difference being statistically significant (p < 0.05). Since the simulation model has no metabolic and circulatory regulatory factors, no chills, heart rate or blood pressure fluctuations occurred during the entire process.

[0083] Table 1. Temperature changes of the brain and whole body of the high-fidelity simulation model (n=5) *Note: Temperature change is the difference between the lowest temperature during the intervention period and the baseline temperature; 95% CI is the 95% confidence interval; WT denotes the Wilcoxon rank sum test. The above results used a nonparametric test to compare the magnitude of the decrease in brain temperature relative to the decrease in whole-body temperature. This indicates that the present invention achieved a localized cooling of approximately 3°C in the simulated human body model, while simultaneously reducing whole-body temperature by less than 2°C.

[0084] Example 2: Pig Animal Experiment The effectiveness and safety of the selective brain cooling method of the present invention were further validated in an animal model. Ten healthy adult domestic pigs (weighing approximately 30 kg) were anesthetized and intubated orally with the device of the present invention, replacing a conventional endotracheal tube. An external permanent magnetic rotational positioning system was used to adjust the distal end of the tube's angle, ensuring that the cooling portion of the tube was in close contact with the anatomical region of the posterior pharyngeal wall. Ventilation was maintained under anesthesia using a ventilator. After the pigs' esophageal and subdural brain temperatures (using a temperature probe placed through a cranial burr hole) were maintained at ~38°C during the stable period, the cooling device was activated for selective brain cooling. The outer wall temperature of the endotracheal tube was maintained at approximately 18°C, and the internal ventilation temperature was maintained at approximately 37°C. Cooling was continued for 60 minutes. Brain temperature (using a subdural probe) and core body temperature (rectal temperature) were continuously monitored, and circulatory and respiratory changes were observed. After 60 minutes, cooling was discontinued and heated gas was administered through the tube for 15 minutes to assist rewarming. No shivering was observed during the experiment, and heart rate and arterial blood pressure remained stable during the cooling process. All pigs had intact pharyngeal mucosa, with no signs of localized hypothermic damage to the catheter. Temperature data before and after cooling are shown in Table 2.

[0085] Results showed that in animal experiments, pig brain temperature dropped from an average baseline of approximately 38.1°C to around 34.0°C, a decrease of approximately 4.1°C. During the same period, rectal temperature dropped from approximately 38.1°C to 37.2°C, a decrease of less than 1°C. This demonstrates that the present invention can significantly reduce brain temperature by approximately 4°C within one hour in a pig model, while having minimal impact on systemic body temperature. Statistical analysis showed that the reduction in brain temperature was significantly greater than that in core body temperature (p ≈ 0.001).

[0086] Table 2 Temperature changes in the pig selective brain cooling experiment (n=10) *Note: Temperature change is the difference between the lowest temperature during the intervention period and the baseline temperature; 95% CI is the 95% confidence interval; P values ​​were calculated using a paired t-test. The results showed that brain temperature significantly decreased in the animal model with minimal changes in whole-body temperature, demonstrating that the device of this invention has the effect of selective brain cooling and is safe and feasible.

[0087] Example 3: Preliminary clinical trial on patients With ethical approval and informed consent, a preliminary clinical trial of the device presented in this paper was conducted on 20 critically ill patients to evaluate its cooling efficacy and safety under real-world clinical conditions. The patients included comatose patients after cardiopulmonary resuscitation with return of spontaneous circulation, patients with ischemic stroke and large cerebral infarction, and patients with severe craniocerebral trauma (aged 18–65 years, both men and women). All patients underwent sedation and intubation in the ICU, with conventional endotracheal tubes replaced with the selective cooling endotracheal tube presented in this paper (the procedure was completed smoothly under close monitoring). After intubation, cooling was initiated according to the previously described parameters: a target temperature of approximately 20°C for the outer tube wall and a constant internal temperature of 37°C. To prevent shivering, adequate sedation and analgesia were administered during induction cooling, supplemented with muscle relaxants if necessary. Basal body temperature (nasopharyngeal temperature representing brain temperature and bladder temperature representing core temperature) before cooling, as well as the lowest brain and core temperatures during cooling, were recorded. Cooling continued for approximately 2 hours, followed by gradual rewarming of each patient. During the cooling process, most patients maintained stable vital signs. A small number of patients experienced manageable physiological reactions: for example, two patients experienced mild bradycardia (minimum heart rate approximately 50 beats / min, requiring no special treatment), and three patients experienced a mild increase in mean arterial pressure of approximately 10 mmHg (possibly related to peripheral vasoconstriction). No serious complications, such as arrhythmias, occurred. None of the patients experienced significant shivering, and no adverse reactions, such as hypotension, occurred during rewarming. Table 3 summarizes the body temperature changes in the clinical patient group. On average, brain temperature decreased from a baseline of approximately 37.5°C to a minimum of approximately 34.2°C, a decrease of approximately 3.3°C. During the same period, core body temperature decreased from approximately 37.6°C to approximately 35.8°C, a decrease of approximately 1.8°C. Statistical analysis showed that the decrease in brain temperature was significantly greater than that in core temperature (p<0.001), demonstrating that the present invention can also achieve selective brain cooling in human patients. This trial preliminarily demonstrates the safety of the present invention: no significant adverse reactions or complications due to the cooling device were observed in the 20 patients observed. After the cooling intervention, the patients continued to be treated according to the conventional intensive care process. The above clinical results provide strong support for the application of the present invention in critically ill patients.

[0088] Table 3 Body temperature changes in clinical patients during the selective brain cooling trial (n=20) *Note: Temperature change is the difference between the lowest temperature during the intervention period and the baseline temperature; 95% CI is the 95% confidence interval; P values ​​were 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, with only a mild decrease in body temperature and no serious adverse events. This provides a new technical approach and reliable data support for the use of selective brain cooling in clinical settings such as post-cardiac arrest brain protection, ischemic stroke, and brain trauma.

Claims

1. A tracheal tube device with rotating permanent magnetic positioning and selective brain cooling function, characterized by: It includes a tracheal tube (1), a temperature and humidity control system, and a rotating permanent magnetic positioning system; A plurality of flexible semiconductor cooling sheets (2) are embedded in a flexible tracheal tube (1) at a certain distance along the extension direction of the tube; the cold ends of all the flexible semiconductor cooling sheets (2) are in contact with the outer wall of the tracheal tube, and the hot ends of the flexible semiconductor cooling sheets (2) are in contact with the inner wall of the tracheal tube (1); a plurality of temperature and humidity sensors (3) are arranged at intervals between the plurality of flexible semiconductor cooling sheets (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 refrigeration piece (2), obtain the temperature and humidity values ​​of the tracheal tube (1) through each temperature and humidity sensor (3), and use PID control to dynamically adjust the voltage of each flexible semiconductor refrigeration piece (2) in combination with a set target temperature threshold, so as 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, an endotracheal 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 installed 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 endotracheal tube assembly includes a magnetic guiding element (5) and a magnetic sensor (4) arranged at the distal end of the endotracheal tube (1). The magnetic guiding element is used to generate a guiding force under the action of an external magnetic field. The magnetic sensor (4) is arranged adjacent to the magnetic guiding element and is used to detect the strength and direction of the external magnetic field and provide a feedback signal. The control module includes a signal processing unit and an execution unit, which are used to collect 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 feedback from the magnetic sensor. The control module adjusts the intensity and direction of the external magnetic field in real time, accurately controlling the position and angle of the magnetic guide element at the distal end of the endotracheal tube to achieve precise positioning of the tube.

2. The endotracheal tube device with rotating permanent magnetic positioning and selective brain cooling function according to claim 1, characterized in that: The temperature and humidity control system includes a MUC module, a plurality of temperature and humidity sensors (3) connected to the MCU control module, a DC-DC converter connected to the MUC, the MCU control module is connected after being isolated from the MOS tube by an optical coupler, each flexible semiconductor cooling sheet (2) is connected to a MOS tube and a DC-DC converter, each MOS tube and DC-DC converter is individually controlled by the MCU control module, the DC-DC converter is used to adjust the output voltage, and the power MOS tube is used to adjust the output current through a PWM signal. After the temperature is set by the MCU control module, the voltage at both ends of the flexible semiconductor cooling sheets (2) in different areas is automatically adjusted to achieve temperature and humidity regulation.

3. The endotracheal tube device with rotating permanent magnetic 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, and the current and voltage actually output to each flexible semiconductor refrigeration sheet (2) are monitored by the current acquisition circuit and the voltage acquisition circuit and fed back to the MCU control module; The current acquisition circuit samples the INA180A2IDBVR current detection amplifier, and the voltage acquisition circuit samples the output voltage using a voltage divider resistor.

4. The endotracheal tube device with rotating permanent magnetic 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 a curve, mapping the collected temperature and humidity data to the coordinate system of the display module. The MCU control module collects the current and voltage data of each flexible semiconductor cooling sheet (2), converts the analog voltage signal into a digital signal through its own ADC module, converts the collected voltage and current data into coordinate values ​​through a preset algorithm, draws a curve, and displays the voltage and current curve on the display module.

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

6. The endotracheal tube device with rotating permanent magnetic positioning and selective brain cooling function according to claim 5, characterized in that: The permanent magnet three-axis drive mechanism comprises 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 in the inner ring (9). The permanent magnet drive motor (8) is installed on the inner ring (9) and is used 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 an 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 an external protection structure for the entire three-axis drive mechanism.

7. The temperature control method of the endotracheal tube device with rotating permanent magnetic positioning and selective brain cooling function according to any one of claims 1 to 4, characterized in that: The temperature and humidity control system uses PID control according to formula (1) to control the voltage of the semiconductor refrigeration chip; u ( t )= K p e ( t )+ K i dτ + K d dtde ( t )（1） in: u ( t ) is the output of the controller, that is, the voltage across the flexible semiconductor refrigeration sheet. e ( t )= Tset − Tactual ( t ) is the set temperature Tset The actual measured temperature Tactual ( t ), K p is the proportional gain, K i is the integral gain, K d is the differential gain; In order to achieve adaptive adjustment of PID parameters, a neural network optimized PID temperature controller is constructed by combining feedforward neural network MLP with PID control; the feedforward neural network MLP outputs the optimal PID gain in real time according to the current state characteristics. , so that the controller can self-regulate with the changes of environment and target; 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 instantly updates the parameters of the PID controller. The PID controller calculates the voltage of the cooling plate based on this, drives the cooling plate to adjust the temperature, and forms a closed-loop control.

8. The temperature control method for the endotracheal tube device with rotating permanent magnetic positioning and selective brain cooling function according to claim 7, characterized in that: A two-layer feedforward neural network MLP is used as the PID parameter regulator, and the activation function uses the linear rectification function ReLU ( ) to enhance the nonlinear expression ability of the network while maintaining the stability of gradient propagation; the output layer consists of 3 nodes, corresponding to the PID controller 、 、 Three gain parameters, the output layer uses linear activation, and the function implemented by the feedforward neural network MLP is expressed as the input vector Nonlinear mapping: in, is the input feature vector; is the temperature at multiple points on the inner wall of the catheter, The temperature of multiple points on the outer wall of the catheter, is the patient's core body temperature, The nasopharyngeal brain temperature is The time for cooling down, is the current cooling rate, Set a value for the target temperature or temperature difference; Neural network real-time calculation function , output the most suitable PID gain combination at the corresponding moment These outputs are used directly in a PID controller to vary its parameters over time: , thus forming an adaptive PID control.

9. The temperature control method for the endotracheal tube device with rotating permanent magnetic positioning and selective brain cooling function according to claim 7, characterized in that: During the training process of the feedforward neural network MLP, the loss function Defined as the mean square value of the temperature control error, for the set value of the outer wall temperature of the tube , using formula (4): in For the The outer wall temperature collected at each moment or the average value of multiple points; If the inner wall temperature error is considered at the same time, the inner wall temperature deviation term is weighted and added to the loss function, and the comprehensive loss function is , by choosing the weight While ensuring the accuracy of outer wall temperature control, it limits the deviation of inner wall temperature from normal body temperature.

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