A PICC catheterization complication intelligent early warning and automatic intervention system

Abstract

The present application relates to biomedical micro-electro-mechanical system and intelligent micro-fluidic technology field, especially to a PICC catheterization complication intelligent early warning and automatic intervention system, including the following modules: in situ multimodal perception module, stochastic resonance calculation early warning module, adaptive stiffness tuning module, bistable pulse excitation module and acoustic metamaterial rectification module. The perception module uses piezoelectric film and fiber Bragg grating to solve the fluid viscous damping coefficient in real time; the early warning module calculates the target barrier height according to the blood flow background noise and generates intervention instructions; the tuning module adjusts the bistable skeleton stiffness through shape memory alloy to match the barrier; the excitation module uses random resonance to drive the skeleton to occur nonlinear jump and generate high-energy pressure shock wave; the rectification module uses acoustic band gap to reflect the near-end shock wave to realize one-way fluid pulse output. The present application uses weak biological energy to break through the high viscous fluid boundary layer damping, realizes the valveless directional physical removal of the micro-attachment in the catheter.

Description

Technical Field

[0001] This invention relates to the field of biomedical microelectromechanical systems and intelligent microfluidics, and in particular to an intelligent early warning and automatic intervention system for PICC placement complications. Background Technology

[0002] Peripherally inserted central catheters (PICCs) are an important channel for long-term treatments such as chemotherapy and parenteral nutrition. However, due to the long indwelling time and small diameter of the catheter, coupled with the fact that the infused medications are usually highly viscous, the inner wall of the catheter is prone to adsorbing plasma proteins and fibrin, forming biofilm precursors or thrombus nucleation sites, which can lead to catheter-related thrombosis or non-thrombotic blockage.

[0003] However, most traditional micropumps are driven by linear pressure waves. Due to the strong energy dissipation of the high-viscosity boundary layer, deep blockages in the conduit cannot be effectively cleared. Summary of the Invention

[0004] To overcome the above shortcomings, this invention provides an intelligent early warning and automatic intervention system for PICC placement complications, which aims to improve the problem that traditional micropumps mostly use linear pressure wave drive, which causes deep catheter blockage that cannot be effectively cleared due to the strong energy dissipation of the high-viscosity boundary layer.

[0005] This invention provides the following technical solution: a PICC placement complication intelligent early warning and automatic intervention system, comprising the following modules: The in-situ multimodal sensing module includes a piezoelectric thin-film hydrophone and a fiber Bragg grating array integrated into the catheter wall, used to acquire venous blood flow background noise signals and catheter wall strain mode signals, and to calculate the fluid viscosity damping coefficient. The stochastic resonance calculation and early warning module is connected to the in-situ multimodal sensing module. It is used to generate a graded intervention command when the viscous damping coefficient exceeds the threshold, and to calculate the target barrier height based on the intensity variance of the background noise signal. An adaptive stiffness tuning module is connected to a bistable preloaded curved beam skeleton inside the conduit. It is used to respond to the graded intervention command and control the shape memory alloy drive connected to the skeleton to adjust the axial preload of the skeleton so that the physical barrier height of the skeleton matches the target barrier height. A bistable pulse excitation module is used to apply a periodic perturbation signal to the adjusted skeleton, and use the random resonance between the background noise signal and the perturbation signal to drive the skeleton to undergo a bistable nonlinear transition, thereby generating a pressure shock wave. The acoustic metamaterial rectification module is a periodic Helmholtz resonant cavity array embedded in the proximal end of the inner wall of the duct. Its acoustic bandgap frequency covers the main frequency of the pressure shock wave, which is used to reflect the pressure shock wave propagating to the proximal end, so that it is superimposed with the pressure shock wave propagating to the distal end to form a unidirectional fluid pulse.

[0006] By adopting the above technical solution, nonlinear shock waves are generated by random resonance driving bistable state and combined with acoustic metamaterial rectification, thereby overcoming the viscous damping of microtubes to achieve valveless unidirectional transport. This improves the problem that traditional micropumps mostly use linear pressure wave drive, which causes deep blockage in the conduit to be unable to be effectively cleared due to the strong energy dissipation of the high-viscosity boundary layer.

[0007] Preferably, the in-situ multimodal sensing module includes: The piezoelectric thin-film hydrophone is used to convert the fluid pressure fluctuations in the vein into electrical signals. The power spectral density variance of the electrical signals is extracted by spectral analysis and used as the energy intensity of the hemodynamic background noise signal. The fiber Bragg grating array is used to detect the center wavelength drift of the duct wall and calculate the real-time micro-strain data of the duct wall. The real-time micro-strain data were subjected to time-domain decay analysis, and the logarithmic decay rate was extracted as a characteristic parameter characterizing the viscous damping state of the fluid boundary layer.

[0008] Preferably, the stochastic resonance calculation early warning module includes: Receive background noise energy intensity data output by the in-situ multimodal sensing module; Retrieve the Kramers escape rate peak point corresponding to the current energy intensity data from the pre-stored matching database, and lock the physical potential energy trap depth value corresponding to the Kramers escape rate peak point. The physical potential energy trap depth is numerically marked as the target barrier height and encapsulated in a digital control signal, which is then sent to the adaptive stiffness tuning module.

[0009] Preferably, the stochastic resonance calculation early warning module further includes: The viscous damping state characteristic parameters calculated by the in-situ multimodal sensing module are compared with a preset threshold. When the characteristic parameter is within the first threshold range, a first-level intervention command is generated, instructing the bistable pulse excitation module to perform micro-oscillations only within a single potential energy trap. When the characteristic parameter is in the second threshold range, a secondary intervention command is generated, instructing the bistable pulse excitation module to perform a large jump across the potential energy barrier.

[0010] Preferably, the adaptive stiffness tuning module includes: The target barrier height in the digital control signal is analyzed and converted into the target resistance threshold based on the pre-stored shape memory alloy resistance-stress characteristic curve. The constant current drive circuit is controlled to output DC bias current to the dynamic skeleton structure inside the conduit, so that it generates thermally induced phase change contraction force. The real-time resistance value of the shape memory alloy is monitored in a closed loop by the resistance feedback unit, and the magnitude of the DC bias current is adjusted until the real-time resistance value stabilizes at the target resistance threshold.

[0011] Preferably, the adaptive stiffness tuning module further includes: The strain response data of the dynamic skeleton structure is collected in real time by the in-situ multimodal sensing module, and a real-time stress-strain hysteresis loop is constructed. Calculate the area enclosed by the hysteresis loop and compare it with a preset standard jump area threshold; If the area value is less than the threshold, it is determined that no effective transition has occurred, and the DC bias current step size output to the power frame structure is automatically increased until an effective transition feature is detected.

[0012] Preferably, the bistable pulse excitation module includes: When the bistable preloaded curved beam is in a critical metastable state, the AC disturbance generator is controlled to superimpose a low-frequency AC micro-perturbation current. The thermal stress fluctuations caused by the low-frequency AC perturbation current are used as a guiding signal to couple the random mechanical energy of the hemodynamic background noise signal. The bistable preloaded curved beam is driven to cross the physical potential energy barrier, and a nonlinear jump occurs between the first steady state and the second steady state, applying an instantaneous compression pulse to the fluid in the duct.

[0013] Preferably, the bistable pulse excitation module further includes: During the execution of nonlinear jump action, Joule heat generated by the shape memory alloy of the driving power skeleton structure is conducted to the temperature-sensitive hydrogel gating unit. When the accumulated heat causes the temperature to exceed the lower critical dissolution temperature, the temperature-sensitive hydrogel gating unit is triggered to undergo a volume shrinkage phase transition, connecting the fluid paths inside and outside the conduit. In conjunction with the fluid driving force of the pressure shock wave, the treatment fluid in the catheter is ejected through the connected path.

[0014] Preferably, the acoustic metamaterial rectification module includes: Based on the center frequency of the pressure shock wave, the ratio of the neck cross-sectional area to the cavity volume of each Helmholtz resonant unit is set to construct an acoustic bandgap covering the center frequency. When the pressure shock wave propagates towards the proximal end of the duct and enters the acoustic bandgap, it excites a local resonance mode, causing the effective bulk modulus of the array distribution area to be negative, resulting in total reflection of the incident wave. By spatiotemporally superimposing the reflected wave with the pressure shock wave component propagating to the distal end of the duct, a unidirectional fluid pulse pointing to the distal end is output.

[0015] Preferably, the acoustic metamaterial rectification module further includes: The time-domain waveform of the pressure shock wave generated by the bistable pulse excitation module is obtained, and its main frequency component is extracted by Fourier transform. Adjust the lattice constant of the periodic array in the acoustic metamaterial rectifier module so that its Bragg scattering frequency coincides with the dominant frequency component; By utilizing the Bragg scattering mechanism, the reflection efficiency of pressure shock waves propagating towards the near end is enhanced, thereby increasing the net flow rate of the fluid pulse output at the far end.

[0016] The present invention has the following beneficial effects: 1. In this invention, by using random resonance to drive bistable state to generate nonlinear shock waves and cooperating with acoustic metamaterial rectification, the viscous damping of microtubes is overcome to achieve valveless unidirectional transport. This improves the problem that traditional micropumps mostly use linear pressure wave drive, which causes deep blockage in the conduit to be unable to be effectively cleared due to the strong energy dissipation of the high-viscosity boundary layer.

[0017] 2. In this invention, the nonlinear transition of the bistable skeleton is driven by the random resonance of blood flow background noise and perturbation signal, thereby reducing the system's driving energy consumption. This improves the problem that traditional implantable micropumps mostly use high-power active drive, which has low energy conversion efficiency and significant heat generation, resulting in short battery life and thermal damage to tissues.

[0018] 3. In this invention, an acoustic bandgap reflection pressure shock wave is constructed and propagates to the near end through an acoustic metamaterial rectification module, thereby realizing unidirectional fluid transport without mechanical valves. This improves the problem that traditional microfluidic systems mostly use micro-mechanical one-way valves, which are prone to biofilm adhesion in the blood environment, resulting in valve jamming failure and catheter backflow.

[0019] 4. In this invention, the fluid viscosity damping is calculated in real time by the in-situ multimodal sensing module and the height of the skeleton barrier is adaptively adjusted, thereby realizing precise intervention based on the early signs of lesions. This improves the problem that most traditional antithrombotic devices adopt a blind operation mode with fixed programs, which cannot identify micro-load changes, resulting in delayed intervention timing and prevention failure. Attached Figure Description

[0020] Figure 1 This is an architecture diagram of an intelligent early warning and automatic intervention system for PICC placement complications proposed in this invention; Figure 2 This invention presents a flowchart illustrating the perception and decision-making process of an intelligent early warning and automatic intervention system for PICC placement complications. Figure 3 This is a flowchart illustrating the tuning and activation process of an intelligent early warning and automatic intervention system for PICC placement complications proposed in this invention. Figure 4 This is an acoustic rectification principle diagram of an intelligent early warning and automatic intervention system for PICC placement complications proposed in this invention. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1: In a first embodiment of the present invention, the present invention provides an intelligent early warning and automatic intervention system for PICC placement complications, such as... Figures 1-4 As shown, it includes the following modules: The in-situ multimodal sensing module includes a piezoelectric thin-film hydrophone and a fiber Bragg grating array integrated into the catheter wall, used to acquire venous blood flow background noise signals and catheter wall strain mode signals, and to calculate the fluid viscosity damping coefficient. Furthermore, the in-situ multimodal sensing module includes: The pressure fluctuations of fluid in the vein are converted into electrical signals using a piezoelectric thin-film hydrophone. The power spectral density variance of the electrical signals is extracted by spectral analysis and used as the energy intensity of the hemodynamic background noise signal. The center wavelength drift of the duct wall was detected using a fiber Bragg grating array, and the real-time micro-strain data of the duct wall was calculated. Time-domain decay analysis was performed on real-time micro-strain data, and the logarithmic decay rate was extracted as a characteristic parameter to characterize the viscous damping state of the fluid boundary layer.

[0023] Specifically, the hardware deployment and signal acquisition involve integrating the in-situ multimodal sensing module into the distal wall structure of the PICC catheter. The hardware sensing unit includes a piezoelectric thin-film hydrophone and a fiber Bragg grating array.

[0024] Piezoelectric film hydrophone: A polyvinylidene fluoride piezoelectric film is wrapped around and adhered to the inner wall of a catheter to sense pressure fluctuations in the fluid within a vein. Pressure waves are generated when blood flow impacts or turbulence occurs. When applied to the surface of a piezoelectric thin film, the piezoelectric effect causes a corresponding charge accumulation in the film, which is then converted into an analog voltage signal by a charge amplifier. This signal characterizes the current hemodynamic background noise within the vein.

[0025] Fiber Bragg grating array: Embedded in a composite material layer along the axial direction of the conduit wall. The grating array is used to monitor minute deformations of the conduit wall under the influence of fluid. When the conduit wall experiences mechanical vibration due to fluid shear force or deposits, the grating pitch of the fiber Bragg grating changes, causing a shift in the center wavelength of the reflected light.

[0026] The calculation process for the hemodynamic background noise energy intensity involves the module receiving the analog voltage signal output from the piezoelectric thin-film hydrophone. After analog-to-digital conversion, digital signal processing is performed.

[0027] Spectrum analysis of the acquired time series signals Perform a Fast Fourier Transform to obtain the power spectral density function of the signal. .

[0028] Energy intensity extraction is based on calculating the energy intensity of background noise using the power spectral density function. The calculation formula is as follows: ; in This represents the energy intensity of the hemodynamic background noise signal, and its physical meaning is the average power of the signal within a specified frequency band. and These represent the lower and upper limits of the preset effective monitoring frequency band, respectively. Indicates frequency as The power spectral density value at that time.

[0029] Data flow direction: calculated It is transmitted to the stochastic resonance calculation and early warning module as the target barrier height for calculation. The input basis.

[0030] The solution process for the viscous damped state of the fluid boundary layer involves the module receiving the optical signal reflected by the fiber Bragg grating array and obtaining the real-time drift of the center wavelength through a demodulator.

[0031] Micro-strain data analysis utilizes the wavelength-strain transfer function to calculate the center wavelength shift. Converted into real-time micro-strain data of the pipe wall The conversion formula is: ; in Indicates time Micro-strain of the pipe wall; Indicates the effective elastic-optical coefficient of the optical fiber material; Indicates time The amount of shift of the center wavelength relative to the initial wavelength; This indicates the initial center wavelength of the fiber optic grating.

[0032] Time-domain decay analysis and damping coefficient extraction reveal that under blood flow pulsation excitation, the vessel wall undergoes forced vibration. The vibration decay characteristics change when a biofilm adheres to the vessel wall surface or the fluid boundary layer viscosity increases. The module processes micro-strain data. Time-domain peak extraction is performed to identify adjacent amplitude peaks, and the logarithmic decay rate is calculated as an intermediate parameter to obtain the equivalent viscous damping coefficient. The calculation formula is as follows: ; ; in Represents the logarithmic decay rate of vibration; Indicates the first The peak amplitude of each vibration cycle; Indicates the first The peak amplitude of each vibration cycle, The selected number of periods is an integer; The equivalent viscous damping coefficient represents the viscous damping state of the fluid boundary layer. Indicates the equivalent mass of the duct wall structure; This represents the damping period of the pipe wall vibration.

[0033] Through the above processing, the module converts the optical signal into a quantized damping coefficient. This coefficient directly reflects the physical load state of the conduit surface. When An increase indicates an increase in fluid viscosity on the pipe wall surface or the presence of deposits.

[0034] Data flow: Calculated equivalent viscous damping coefficient The value is output to the stochastic resonance calculation and early warning module. The early warning module compares this value with a preset safety threshold; if... If the threshold is exceeded, the fluid boundary layer is determined to be abnormal, triggering a graded intervention command.

[0035] The stochastic resonance calculation and early warning module is connected to the in-situ multimodal sensing module. It is used to generate graded intervention commands when the viscous damping coefficient exceeds the threshold, and to calculate the target barrier height based on the intensity variance of the background noise signal. Furthermore, the stochastic resonance computational early warning module includes: Receive background noise energy intensity data output from the in-situ multimodal sensing module; Retrieve the Kramers escape rate peak point corresponding to the current energy intensity data from the pre-stored matching database, and lock the physical potential energy trap depth value corresponding to the Kramers escape rate peak point. The physical potential energy trap depth is numerically marked as the target barrier height and encapsulated in a digital control signal, which is then sent to the adaptive stiffness tuning module.

[0036] The stochastic resonance calculation early warning module also includes: The viscous damping state characteristic parameters calculated by the in-situ multimodal sensing module are compared with the preset threshold. When the characteristic parameter is within the first threshold range, a first-level intervention command is generated, instructing the bistable pulse excitation module to perform micro-oscillations only within a single potential energy trap. When the characteristic parameters are in the second threshold range, a secondary intervention command is generated, instructing the bistable pulse excitation module to perform a large jump across the potential energy barrier.

[0037] Specifically, the stochastic resonance computational early warning module is built on a microprocessor or edge computing chip and is mainly responsible for establishing the matching relationship between environmental noise and physical structure parameters, and determining the system's intervention strategy based on the fluid load state.

[0038] The process of calculating and locking the target barrier height involves the module receiving background noise energy intensity data output from the in-situ multimodal sensing module. This data reflects the current level of available random energy within the vein. The module's internal storage unit contains a pre-configured matching database, built upon the stochastic resonance theory of bistable systems, which records the potential well depth required for the system to achieve its optimal response under different noise intensities.

[0039] The retrieval and matching processor receives the data. The index is used to perform a search in the matching database. The goal of the search is to find the combination of physical parameters that maximizes the Cramers escape rate. The Cramers escape rate describes the probability rate at which a particle crosses a potential barrier under noise-driven conditions, and its calculation formula is as follows: ; in This represents the Kramers escape rate, which is the average frequency at which the system transitions from one steady state to another. This represents the oscillation angular frequency of the particle at the bottom of the potential energy trap, which is determined by the linear stiffness of the bistable system. It represents the angular frequency of the particle's oscillation at the top of the potential barrier, which is determined by the curvature at the top of the barrier; This represents the system's damping coefficient, which is considered a constant here or corrected by the real-time damping value input from the sensing module; This indicates the depth of the physical potential energy trap, i.e., the height of the target barrier; This indicates the energy intensity of the background noise.

[0040] The numerical locking and signal encapsulation module finds the signal by performing traversal calculations or looking up tables. When the signal-to-noise ratio is at its maximum for weak periodic signals The value is locked as the target barrier height. This value represents the critical stiffness state at which a bistable structure is most easily triggered into a transition by a weak driving force under the current noisy environment. The processor will... The signal is encoded as a digital control signal and sent to the adaptive stiffness tuning module via the communication interface.

[0041] The process of generating graded intervention instructions involves the module receiving the equivalent viscous damping coefficient calculated by the in-situ multimodal sensing module. This coefficient reflects the degree of biofilm adhesion or thrombosis tendency on the catheter surface. The module has a built-in preset first threshold. Second threshold ,and .

[0042] Threshold comparison logic, the processor will input in real time Compare the values ​​with the preset threshold.

[0043] Level 1 intervention instructions are generated when the comparison results meet the requirements. At this point, it is determined that there is initial stagnation or trace adhesion in the fluid boundary layer. The module generates a first-level intervention command. This command includes amplitude limiting parameters, instructing the subsequent bistable pulse excitation module to maintain motion within a single potential energy trap. At this time, the system uses micro-amplitude nonlinear oscillations that do not cross the potential barrier to generate local disturbances, physically disrupting the laminar structure of the fluid boundary layer and preventing material deposition.

[0044] Secondary intervention instructions are generated when the comparison results meet the requirements. At this point, if a significant risk of biofilm formation or thrombus formation is detected in the vessel wall, the module generates a secondary intervention command. This command removes the amplitude limitation and activates the cross-well transition logic. The system then utilizes stochastic resonant energy to overcome the potential energy barrier. A rapid, dramatic transition occurs between two steady states. This transition releases a high-energy pressure shock wave into the fluid, which can be used to physically peel off adhering substances or propel the liquid agent.

[0045] Data flow: The generated primary or secondary intervention commands are directly transmitted to the bistable pulse excitation module and the temperature-sensitive hydrogel gating unit to trigger the corresponding physical actions.

[0046] The adaptive stiffness tuning module is connected to the bistable preloaded curved beam skeleton inside the conduit. It is used to respond to graded intervention commands and control the shape memory alloy drive connected to the skeleton to adjust the axial preload of the skeleton so that the physical barrier height of the skeleton matches the target barrier height. Furthermore, the adaptive stiffness tuning module includes: The target barrier height in the digital control signal is analyzed and converted into the target resistance threshold based on the pre-stored shape memory alloy resistance-stress characteristic curve. The constant current drive circuit is controlled to output DC bias current to the dynamic skeleton structure inside the conduit, so that it generates thermally induced phase change contraction force. The real-time resistance value of the shape memory alloy is monitored in a closed loop by a resistance feedback unit, and the magnitude of the DC bias current is adjusted until the real-time resistance value stabilizes at the target resistance threshold.

[0047] The adaptive stiffness tuning module also includes: The strain response data of the dynamic skeleton structure is collected in real time by the in-situ multimodal sensing module, and a real-time stress-strain hysteresis loop is constructed. Calculate the area enclosed by the hysteresis loop and compare it with a preset standard jump area threshold; If the area value is less than the threshold, it is determined that no effective transition has occurred, and the DC bias current step size output to the power frame structure is automatically increased until an effective transition feature is detected.

[0048] Specifically, the adaptive stiffness tuning module consists of a constant current drive circuit, a resistance feedback unit, and a logic processing unit. It is configured to adjust the mechanical properties of the bistable preloaded curved beam skeleton so that its physical barrier height is precisely matched with the calculated target barrier height.

[0049] Based on the structural stiffness tuning process using resistance feedback, the module receives the target barrier height from the random resonance calculation and early warning module. Digital control signals.

[0050] Target parameter analysis and conversion: The resistivity of shape memory alloys (SMAs) changes nonlinearly with their crystal phase and strain state, directly corresponding to changes in their elastic modulus and output stress. The logic processing unit calls a pre-stored database of SMA resistance-stress characteristic curves to establish a mapping relationship between the target barrier height and the SMA resistance value. The conversion process follows the mapping function: ; in This represents the target resistance threshold corresponding to the target stiffness state. This represents a nonlinear mapping function pre-calibrated based on the SMA material properties; Indicates the height of the target barrier.

[0051] Constant current drive and closed-loop regulation: The logic processing unit controls the constant current drive circuit to output the initial DC bias current to the SMA driver connected to both ends of the frame. The current flowing through the SMA drive component generates Joule heating, inducing phase change contraction, which in turn changes the axial preload of the preloaded curved beam frame. .

[0052] The resistance feedback unit uses a four-terminal measurement method to monitor the voltage across the SMA driver in real time. and current According to Ohm's Law Calculate the real-time resistance value. The logic processing unit calculates the real-time resistance value. With target resistance threshold deviation The output current is dynamically adjusted using a proportional-integral-differential algorithm. ; Through continuous adjustment until Approaching zero, the SMA actuator is maintained at a specific phase transition ratio, thereby locking the physical barrier height of the bistable framework at [value missing]. .

[0053] The closed-loop feedback calibration process based on hysteresis loops executes verification logic based on energy dissipation characteristics to verify whether the tuned structure is in a critical state capable of random resonance.

[0054] Hysteresis loop construction: The module synchronously receives dynamic skeleton strain data collected by the in-situ multimodal sensing module. and stress data derived from driving parameters During a complete cycle of applying a periodic perturbation signal. Within this framework, a real-time stress-strain hysteresis loop is constructed.

[0055] Energy dissipation calculation and state determination: Bistable systems exhibit significant nonlinear damping characteristics during cross-well transitions, and the area enclosed by the hysteresis loop represents the energy dissipation of a single transition. The processor calculates the area of ​​the hysteresis loop. : ; in The area of ​​the hysteresis loop represents the numerical value, characterizing the degree of nonlinear jump in the system; , Indicates the first Stress and strain values ​​at each sampling point; This represents the total number of sampling points.

[0056] Step size adaptive correction, the module will calculate the... Compared with the preset standard jump area threshold Compare. If The system is currently undergoing only small-amplitude linear oscillations within a single potential well, without the expected cross-well transition, indicating a mismatch between the current barrier height and noise intensity. The logic processing unit automatically increases the adjustment step size of the DC bias current. It updates the target resistance threshold, forcing the SMA actuator to further contract or relax, changing the steady-state configuration of the skeleton, until detection occurs. This confirms the presence of a valid transition feature.

[0057] Data flow: The status signal after calibration is sent to the bistable pulse excitation module, allowing it to start the formal excitation procedure.

[0058] The bistable pulse excitation module is used to apply periodic perturbation signals to the adjusted skeleton, and use the random resonance between the background noise signal and the perturbation signal to drive the skeleton to undergo bistable nonlinear transitions, thereby generating pressure shock waves. Furthermore, the bistable pulse excitation module includes: When the bistable preloaded curved beam is in a critical metastable state, the AC disturbance generator is controlled to superimpose a low-frequency AC micro-perturbation current. The thermal stress fluctuations induced by low-frequency alternating micro-perturbation current are used as a guiding signal to couple the random mechanical energy of the hemodynamic background noise signal. The bistable preloaded curved beam is driven to cross the physical potential energy barrier, and a nonlinear jump occurs between the first and second steady states, applying an instantaneous compression pulse to the fluid inside the duct.

[0059] The bistable pulse excitation module also includes: During the execution of nonlinear jump action, Joule heat generated by the shape memory alloy of the driving power skeleton structure is conducted to the temperature-sensitive hydrogel gating unit. When the accumulated heat causes the temperature to exceed the lower critical dissolution temperature, the thermosensitive hydrogel gating unit is triggered to undergo a volume shrinkage phase transition, connecting the fluid paths inside and outside the conduit. Combined with the fluid driving force of the pressure shock wave, the treatment fluid in the catheter is ejected through the connected path.

[0060] Specifically, the bistable pulse excitation module serves as the power core and fluid drive unit of the system, performing physical shock wave generation based on random resonance and heat-fluid coupling drug release functions.

[0061] In the nonlinear stochastic resonance excitation process, the module receives a state confirmation signal from the adaptive stiffness tuning module, confirming that the bistable preloaded curved beam skeleton is in a critical metastable state. At this point, the potential energy trap depth of the skeleton has been adjusted to match the ambient noise intensity.

[0062] A perturbation signal is injected, and a low-frequency AC perturbation current is superimposed onto the shape memory alloy drive wires connected to both ends of the frame by an AC perturbation generator. The Joule heating generated by the electric current causes periodic, minute fluctuations in the temperature of the drive wire, which in turn generates alternating thermal stress within the shape memory alloy. This thermal stress, acting as a guiding signal, is insufficient in amplitude to drive the frame across the potential energy barrier on its own.

[0063] Energy coupling and cross-well jump: the total driving force on the shape memory alloy driving wire The system is composed of random mechanical forces generated by the basic bias force, alternating thermal stress, and hemodynamic background noise. When the total driving force satisfies the barrier crossing condition, the skeleton undergoes a nonlinear transition from the first steady state to the second steady state. The crossing condition is expressed as follows: ; in This represents the basic axial preload generated by the DC bias current, used to maintain the critical metastable state; The thermo-mechanical conversion coefficient of shape memory alloys reflects the proportional relationship between the square of the current and the generated thermal stress. This represents the instantaneous value of the input low-frequency AC perturbation current; This represents the equivalent random force of hemodynamic background noise acting on the catheter wall; This represents the critical barrier force required for a bistable preloaded curved beam to achieve a steady-state transition under the current configuration.

[0064] When a pressure shock wave is generated and the skeleton undergoes a sudden change, its geometry flips within milliseconds. This mechanical action instantaneously compresses the fluid channel within the conduit lumen, causing a sharp reduction in the channel's cross-sectional area. The fluid is rapidly compressed, generating a pressure shock wave with a steep rise edge. The shock wave propagates along the fluid channel to both ends, serving as a basis for subsequent physical descaling or acoustic rectification and transport.

[0065] The thermo-fluid coupled gated drug delivery process utilizes the associated heat generated by the shape memory alloy drive wire during the maintenance of metastable state and the excitation of jump to control the opening and closing of the drug channel.

[0066] Heat accumulation and conduction occur as the shape memory alloy drive wire continuously generates heat when energized. This generates Joule heating. The heat is transferred through the heat-conducting medium layer on the catheter wall to the temperature-sensitive hydrogel embolism filling the outlet micropores. The instantaneous temperature of the temperature-sensitive hydrogel embolism... The relationship between time and heat follows the heat balance equation: ; in This indicates the specific heat capacity of the thermosensitive hydrogel; This indicates the quality of the thermosensitive hydrogel embolization; Indicates the instantaneous temperature of the thermosensitive hydrogel; This represents the thermal conductivity coefficient from the driving filament to the hydrogel. This represents the effective value of the total current flowing through the shape memory alloy; This indicates the resistance value of the shape memory alloy drive wire; This represents the convective heat transfer coefficient between the catheter surface and the blood environment. Indicates the heat dissipation surface area; This indicates the background temperature of venous blood.

[0067] Phase change activation and fluid jetting, when When the temperature exceeds the lower critical dissolution temperature of the thermosensitive hydrogel, a hydrophobic phase transition occurs, and the hydrogel shrinks significantly in volume. The shrunken gel no longer blocks the outflow micropores, and the fluid pathway becomes open. At this point, a pressure shock wave is generated. The therapeutic fluid in the reservoir channel is propelled through the opened micro-orifice and sprayed out of the catheter in a pulse form, directly acting on the lesion area.

[0068] Data flow: The module outputs physical pressure waves and liquid flow, and simultaneously feeds back the real-time electrical parameters of the shape memory alloy to the adaptive stiffness tuning module for closed-loop monitoring of the transition state.

[0069] The acoustic metamaterial rectification module is a periodic Helmholtz resonant cavity array embedded in the proximal end of the inner wall of the duct. Its acoustic bandgap frequency covers the main frequency of the pressure shock wave, which is used to reflect the pressure shock wave propagating to the proximal end, so that it is superimposed with the pressure shock wave propagating to the distal end to form a unidirectional fluid pulse. Furthermore, the acoustic metamaterial rectification module includes: Based on the center frequency of the pressure shock wave, the ratio of the neck cross-sectional area to the cavity volume of each Helmholtz resonant unit is set to construct an acoustic bandgap covering the center frequency. When the pressure shock wave propagates into the acoustic bandgap near the proximal end of the duct, it excites a local resonance mode, causing the effective bulk modulus of the array distribution area to be negative, resulting in total reflection of the incident wave. By spatiotemporally superimposing the reflected wave with the pressure shock wave component propagating to the distal end of the duct, a unidirectional fluid pulse pointing to the distal end is output.

[0070] The acoustic metamaterial rectification module also includes: The time-domain waveform of the pressure shock wave generated by the bistable pulse excitation module is obtained, and its main frequency component is extracted by Fourier transform. Adjust the lattice constant of the periodic array in the acoustic metamaterial rectifier module so that its Bragg scattering frequency coincides with the dominant frequency component; By utilizing the Bragg scattering mechanism, the reflection efficiency of pressure shock waves propagating towards the near end is enhanced, thereby increasing the net flow rate of the fluid pulse output at the far end.

[0071] Specifically, the acoustic metamaterial rectification module, as a unidirectional control device for the fluid waveguide, is constructed based on the principles of acoustic local resonance and Bragg scattering. Its physical structure is embedded in the proximal wall of the PICC conduit to rectify the shock wave generated by the bistable pulse excitation module, thereby achieving valveless unidirectional fluid transport.

[0072] The geometric parameters of the Helmholtz resonant unit were designed and the band gap was constructed. The core structure of the module is an array of Helmholtz resonant cavities arranged periodically along the duct axis.

[0073] Resonance frequency matching design to obtain pressure shock waves generated by the bistable pulse excitation module Perform a Fast Fourier Transform on the time-domain waveform to extract the dominant frequency component with concentrated energy. Based on the main frequency Define the geometry of each Helmholtz resonant element. Resonant frequency. Determined by the following formula: ; in Indicates the speed of sound in a fluid; This indicates the cross-sectional area of ​​the neck of the resonant cavity, which is directly connected to the central flow channel of the duct. This indicates the volume of the cavity embedded inside the pipe wall; Indicates the effective length of the neck.

[0074] Module configuration geometric parameters enable This allows for the creation of an acoustic bandgap around that frequency.

[0075] Negative effective modulus and total internal reflection are achieved when the frequency is When the pressure shock wave propagates towards the proximal end of the duct and enters the array region, the acoustic frequency falls into the bandgap. At this time, the dynamic response of the array distribution region exhibits a negative effective bulk modulus. : ; in Represents the static bulk modulus of a fluid; Indicates the geometric fill factor of the array; Indicates the shock wave angular frequency; Indicates the resonant angular frequency; This represents the damping coefficient.

[0076] when When the pressure wave propagation constant in this region becomes a purely imaginary number, the wave amplitude decays exponentially, making it unable to penetrate the region and resulting in total reflection.

[0077] The lattice constant tuning process based on Bragg scattering, in addition to utilizing local resonance, also leverages the Bragg scattering characteristics of periodic structures to enhance reflection efficiency.

[0078] The lattice constant calculation module is based on the dominant wavelength of the pressure shock wave. Adjusting the spacing between adjacent resonant units in the array, i.e., the lattice constant. To satisfy the Bragg reflection condition, we set... for: ;in It is a positive integer, usually 1.

[0079] Enhanced reflection and directional transport occur when the lattice constant meets the above conditions, causing the Bragg scattering bandgap generated by the periodic structure to overlap or couple with the local resonance bandgap. This dual mechanism significantly widens the bandgap and deepens the attenuation, ensuring efficient reflection of the backward-propagating shock wave. The reflected pressure wave... Pressure waves propagating forward from bistable sources The phase satisfies the constructive interference condition, and the superposition forms a high-energy fluid pulse that propagates to the distal end of the duct, thereby increasing the net flow output.

[0080] Data flow: The module does not need to actively output electrical signals, but instead passively rectifies the fluid pressure wave directly through the acoustic characteristics of the physical structure, and outputs directional fluid pulses.

[0081] Example 2: This invention addresses the early prevention and treatment of "silent" complications during long-term PICC catheter placement in cancer patients. In such clinical applications, patients are often in a hypercoagulable state and receive long-term infusions of highly viscous chemotherapy drugs, making them highly susceptible to the formation of invisible biofilm precursor layers or thrombus nucleation sites on the catheter inner wall at night or during periods of resting blood flow. The core physical challenge of existing technologies for this scenario lies in the strong dissipation and immune effects of the highly viscous boundary layer on conventional fluid dynamics within a confined microscale space. Due to the extremely small inner diameter of the PICC catheter, fluid behavior is dominated by Stokes flow at low Reynolds numbers, with viscous forces playing a dominant role. Traditional clinical laminar flow flushing is limited by the "no-slip" boundary condition, making it difficult for fluid shear forces to effectively act on the adhesion layer tightly adhering to the catheter wall. Furthermore, the conventional linear pressure waves generated by existing micropumps are prone to severe energy dissipation and attenuation along the path when traversing the highly damped biofilm boundary layer, failing to maintain sufficient energy density to disrupt adhesion at the distal end of long-distance catheters. To solve these problems, this invention provides an intelligent early warning and automatic intervention system for PICC placement complications, the structure of which is as follows: Figure 1 As shown. The specific implementation process of this system is as follows: The in-situ multimodal sensing module utilizes the underwater acoustic transduction characteristics of piezoelectric films and the wavelength drift detection function of fiber optic gratings to quantify the hemodynamic background noise energy and calculate the fluid viscosity damping coefficient characterizing the degree of adhesion load on the catheter inner wall. The stochastic resonance calculation and early warning module, based on the intensity variance of the background noise, inversely calculates the optimal Kramers escape rate and the corresponding target barrier height required to induce stochastic resonance, triggering graded intervention logic only when the damping coefficient exceeds the limit. The adaptive stiffness tuning module controls the phase transition contraction of the shape memory alloy to physically adjust the axial preload of the bistable preloaded curved beam frame, forcing the physical barrier height of the mechanical structure to match the calculated target value, establishing a critical metastable state sensitive to weak energy. The bistable pulse excitation module introduces weak periodic perturbations in the critical state, coupling blood flow noise energy to drive the frame to cross the potential energy barrier, releasing elastic potential energy through nonlinear jumps, generating a pressure shock wave with a steep rise edge within the tube. The acoustic metamaterial rectification module constructs an acoustic bandgap by embedding a Helmholtz resonant cavity array in the tube wall. This causes the backward propagating shock wave falling into the frequency band to encounter the negative effective bulk modulus interface and undergo total reflection. The reflected wave and the forward wave are superimposed to form a unidirectional transport high-energy fluid pulse, realizing directional physical removal without mechanical valves.

[0082] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A smart early warning and automatic intervention system for PICC placement complications, characterized in that, Includes the following modules: The in-situ multimodal sensing module includes a piezoelectric thin-film hydrophone and a fiber Bragg grating array integrated into the catheter wall, used to acquire venous blood flow background noise signals and catheter wall strain mode signals, and to calculate the fluid viscosity damping coefficient. The stochastic resonance calculation and early warning module is connected to the in-situ multimodal sensing module. It is used to generate a graded intervention command when the viscous damping coefficient exceeds the threshold, and to calculate the target barrier height based on the intensity variance of the background noise signal. An adaptive stiffness tuning module is connected to a bistable preloaded curved beam skeleton inside the conduit. It is used to respond to the graded intervention command and control the shape memory alloy drive connected to the skeleton to adjust the axial preload of the skeleton so that the physical barrier height of the skeleton matches the target barrier height. A bistable pulse excitation module is used to apply a periodic perturbation signal to the adjusted skeleton, and use the random resonance between the background noise signal and the perturbation signal to drive the skeleton to undergo a bistable nonlinear transition, thereby generating a pressure shock wave. The acoustic metamaterial rectification module is a periodic Helmholtz resonant cavity array embedded in the proximal end of the inner wall of the duct. Its acoustic bandgap frequency covers the main frequency of the pressure shock wave, which is used to reflect the pressure shock wave propagating to the proximal end, so that it is superimposed with the pressure shock wave propagating to the distal end to form a unidirectional fluid pulse.

2. The intelligent early warning and automatic intervention system for PICC placement complications according to claim 1, characterized in that, The in-situ multimodal sensing module includes: The piezoelectric thin-film hydrophone is used to convert the fluid pressure fluctuations in the vein into electrical signals. The power spectral density variance of the electrical signals is extracted by spectral analysis and used as the energy intensity of the hemodynamic background noise signal. The fiber Bragg grating array is used to detect the center wavelength drift of the duct wall and calculate the real-time micro-strain data of the duct wall. The real-time micro-strain data were subjected to time-domain decay analysis, and the logarithmic decay rate was extracted as a characteristic parameter characterizing the viscous damping state of the fluid boundary layer.

3. The intelligent early warning and automatic intervention system for PICC placement complications according to claim 1, characterized in that, The stochastic resonance calculation and early warning module includes: Receive background noise energy intensity data output by the in-situ multimodal sensing module; Retrieve the Kramers escape rate peak point corresponding to the current energy intensity data from the pre-stored matching database, and lock the physical potential energy trap depth value corresponding to the Kramers escape rate peak point. The physical potential energy trap depth is numerically marked as the target barrier height and encapsulated in a digital control signal, which is then sent to the adaptive stiffness tuning module.

4. The intelligent early warning and automatic intervention system for PICC placement complications according to claim 1, characterized in that, The stochastic resonance calculation and early warning module also includes: The viscous damping state characteristic parameters calculated by the in-situ multimodal sensing module are compared with a preset threshold. When the characteristic parameter is within the first threshold range, a first-level intervention command is generated, instructing the bistable pulse excitation module to perform micro-oscillations only within a single potential energy trap. When the characteristic parameter is in the second threshold range, a secondary intervention command is generated, instructing the bistable pulse excitation module to perform a large jump across the potential energy barrier.

5. The intelligent early warning and automatic intervention system for PICC placement complications according to claim 1, characterized in that, The adaptive stiffness tuning module includes: The target barrier height in the digital control signal is analyzed and converted into the target resistance threshold based on the pre-stored shape memory alloy resistance-stress characteristic curve. The constant current drive circuit is controlled to output DC bias current to the dynamic skeleton structure inside the conduit, so that it generates thermally induced phase change contraction force. The real-time resistance value of the shape memory alloy is monitored in a closed loop by the resistance feedback unit, and the magnitude of the DC bias current is adjusted until the real-time resistance value stabilizes at the target resistance threshold.

6. The intelligent early warning and automatic intervention system for PICC placement complications according to claim 1, characterized in that, The adaptive stiffness tuning module also includes: The strain response data of the dynamic skeleton structure is collected in real time by the in-situ multimodal sensing module, and a real-time stress-strain hysteresis loop is constructed. Calculate the area enclosed by the hysteresis loop and compare it with a preset standard jump area threshold; If the area value is less than the threshold, it is determined that no effective transition has occurred, and the DC bias current step size output to the power frame structure is automatically increased until an effective transition feature is detected.

7. The intelligent early warning and automatic intervention system for PICC placement complications according to claim 1, characterized in that, The bistable pulse excitation module includes: When the bistable preloaded curved beam is in a critical metastable state, the AC disturbance generator is controlled to superimpose a low-frequency AC micro-perturbation current. The thermal stress fluctuations caused by the low-frequency AC perturbation current are used as a guiding signal to couple the random mechanical energy of the hemodynamic background noise signal. The bistable preloaded curved beam is driven to cross the physical potential energy barrier, and a nonlinear jump occurs between the first steady state and the second steady state, applying an instantaneous compression pulse to the fluid in the duct.

8. The intelligent early warning and automatic intervention system for PICC placement complications according to claim 1, characterized in that, The bistable pulse excitation module further includes: During the execution of nonlinear jump action, Joule heat generated by the shape memory alloy of the driving power skeleton structure is conducted to the temperature-sensitive hydrogel gating unit. When the accumulated heat causes the temperature to exceed the lower critical dissolution temperature, the temperature-sensitive hydrogel gating unit is triggered to undergo a volume shrinkage phase transition, connecting the fluid paths inside and outside the conduit. In conjunction with the fluid driving force of the pressure shock wave, the treatment fluid in the catheter is ejected through the connected path.

9. The intelligent early warning and automatic intervention system for PICC placement complications according to claim 1, characterized in that, The acoustic metamaterial rectification module includes: Based on the center frequency of the pressure shock wave, the ratio of the neck cross-sectional area to the cavity volume of each Helmholtz resonant unit is set to construct an acoustic bandgap covering the center frequency. When the pressure shock wave propagates towards the proximal end of the duct and enters the acoustic bandgap, it excites a local resonance mode, causing the effective bulk modulus of the array distribution area to be negative, resulting in total reflection of the incident wave. By spatiotemporally superimposing the reflected wave with the pressure shock wave component propagating to the distal end of the duct, a unidirectional fluid pulse pointing to the distal end is output.

10. The intelligent early warning and automatic intervention system for PICC placement complications according to claim 1, characterized in that, The acoustic metamaterial rectification module also includes: The time-domain waveform of the pressure shock wave generated by the bistable pulse excitation module is obtained, and its main frequency component is extracted by Fourier transform. Adjust the lattice constant of the periodic array in the acoustic metamaterial rectifier module so that its Bragg scattering frequency coincides with the dominant frequency component; By utilizing the Bragg scattering mechanism, the reflection efficiency of pressure shock waves propagating towards the near end is enhanced, thereby increasing the net flow rate of the fluid pulse output at the far end.

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