Flexible ostomy bag liquid level-temperature bimodal monitoring device and method based on liquid metal stress buffer interconnection

Abstract

The invention discloses a flexible ostomy bag liquid level-temperature bimodal monitoring device and method based on liquid metal stress buffer interconnection. The device comprises a flexible sensing unit, an FPC integrated control unit, a flexible interconnection structure, a flexible packaging layer and an ostomy bag adaptation layer. Wherein the flexible sensing unit uses a conductive silver paste composite material to construct an interdigital capacitor electrode so as to accurately monitor the liquid level, and uses a PEDOT: PSS / MWCNTs nanocomposite material to construct a resistance temperature electrode so as to sensitively monitor the temperature; the stress buffer layer is constructed through the liquid metal, and anti-fatigue reliable interconnection of the flexible sensor and the rigid FPC is achieved. And the FPC integrated control unit carries an FDC2214 capacitance detection chip and an ESP32 dual-mode communication chip, so that efficient processing and wireless transmission of signals are realized. In combination with an asymmetric sampling strategy, low-power-consumption synchronous monitoring of the liquid level and the temperature is achieved, and the problems of signal interference and connection failure under complex deformation are solved.

Description

Technical Field

[0001] This invention belongs to the field of intelligent medical care device technology, and relates to a dual-modal monitoring device and method for ostomy bag liquid level-temperature, specifically a flexible ostomy bag liquid level-temperature dual-modal monitoring device and method based on liquid metal stress buffer interconnection. Background Technology

[0002] As an essential medical device for postoperative excretion management in patients with colorectal cancer, bladder cancer, and inflammatory bowel disease, the reliability of ostomy bags directly affects patients' quality of life and clinical prognosis. On the one hand, the excrement (feces, urine, etc.) inside the ostomy bag is a highly corrosive fluid, and real-time fluid level monitoring is crucial for preventing leakage due to overflow and the resulting peristaltic dermatitis. On the other hand, the thermodynamic state of the excrement is an important clinical indicator reflecting the presence of infection, ischemic necrosis, or systemic inflammatory response at the stoma site. Clinical data shows that when the fluid temperature inside the bag is abnormally elevated (e.g., >38.5℃), it usually indicates a significantly increased risk of local infection. However, current stoma care mainly relies on patients' subjective feelings or intermittent visual inspections by medical staff, lacking continuous and quantitative monitoring methods. Although a few ostomy bag monitoring schemes based on electronic sensors have been proposed in recent years, the existing technology still has significant defects: (1) poor mechanical compatibility: most existing liquid level sensors use rigid PCBs or flexible circuits (FPCs) based on traditional metal thin films. Their Young's modulus is seriously mismatched with the soft ostomy bag and human skin. When the patient moves and wrinkles, the sensor is prone to falling off or causing discomfort when wearing it; (2) rigid-flexible interconnection is prone to failure: traditional technology usually uses conductive glue or low-temperature solder paste to connect rigid chips and flexible circuits. Under the frequent stretching and compression of the ostomy bag, this solid connection interface is prone to stress concentration and fatigue fracture, resulting in signal transmission interruption; (3) contradiction between corrosion resistance and sensitivity: conventional metal electrodes are easily corroded in the excrement environment, while ordinary carbon-based electrodes are corrosion resistant but have poor conductivity and temperature sensitivity, making it difficult to meet the requirements of high-precision liquid level and temperature monitoring at the same time. Therefore, developing an intelligent monitoring device with high biocompatibility, excellent mechanical flexibility and reliable rigid-flexible connection has become a technical problem that urgently needs to be solved in this field.

[0003] In terms of fluid level monitoring, existing technologies have significant fundamental limitations. Existing technologies (such as the ostomy bag and its volume detection system disclosed in CN119950160A) primarily rely on discrete rigid or semi-rigid components such as magnetic field information collectors and bending sensors for indirect measurement. This approach faces two major challenges: First, poor wearing reliability due to "mechanical mismatch." Because the Young's modulus (GPa level) of these functional components is much higher than that of flexible ostomy bag membrane materials (such as PVDC or EVA, MPa level), there is a huge mechanical impedance mismatch between the two. During daily dynamic activities such as walking, bending over, or turning over, the rigid components cannot conformally deform with the ostomy bag surface, leading to severe shear stress concentration at the contact interface. This easily causes sensor delamination and peeling, and causes significant foreign body sensation and pressure on the patient's abdomen. Second, there is the nonlinear error in the "shape-volume" mapping. Sensors based on magnetic field distance or bending resistance principles essentially monitor the geometric deformation of the bag rather than the actual volume of the internal fluid. Because ostomy bags are flexible fluid containers, their shape changes are highly random. Changes in the gravitational component caused by changes in body position or random wrinkles in the bag itself are often misinterpreted by sensors as changes in fluid level (artifact signals). Experiments show that such solutions often have a fluid level calculation error exceeding 10% in dynamic scenarios and suffer from severe hysteresis effects, failing to meet the stringent clinical requirements for precise and continuous monitoring of excretion volume.

[0004] Regarding multidimensional sensing capabilities, existing intelligent ostomy bag technologies generally suffer from a design bias of prioritizing fluid level over physicochemical indicators. Most focus solely on measuring single physical quantities like fluid level or weight, neglecting the strong correlation between the thermodynamic state of stoma excrement—temperature—and the patient's pathophysiological state. While some existing technologies, such as CN116829108A, attempt to integrate temperature sensors into the chassis to detect skin inflammation, these solutions typically rely on discrete, rigid thermosensitive elements, making it difficult to achieve large-area, conformal, real-time monitoring of fluid temperature within the ostomy bag. Clinical data indicates that abnormally elevated stoma microenvironment or excrement temperature, such as a sustained level >38.5℃, is often an early indicator of local stoma infection, ischemic necrosis, or systemic inflammatory response, with a corresponding skin infection risk increasing by more than 40%. However, traditional nursing models still primarily rely on the patient's subjective sensation or intermittent temperature measurements by healthcare workers. This discrete and lagging monitoring method fails to capture the "thermal anomaly window" in the early stages of pathological changes, leading to missed opportunities for optimal anti-infection intervention.

[0005] In terms of system integration and interactive experience, existing technical solutions such as CN119950160A generally suffer from bloated architecture and unstable wear. To achieve wireless transmission, existing products mostly adopt a distributed architecture of "sensor-display separation," heavily relying on external terminals such as alarm wristbands or dedicated receivers. This design not only forces patients to bear the burden of power maintenance and pairing of multiple devices, but also renders the monitoring function immediately ineffective if the external terminal is powered off or lost. More seriously, limited by traditional PCB manufacturing processes, existing information transmission modules are typically based on a rigid vertical stacking of discrete electronic components. This architecture results in a huge redundancy in the device's envelope volume (typically >15 cm). 3 Furthermore, its center of gravity is relatively high. This rigid and heavy external module disrupts the flexible continuity of the ostomy bag surface. When the patient walks or turns over, the protruding module will generate a severe "pendulum effect" due to the component of gravity. The amplified interfacial shear torque thus easily overcomes the adhesive force of the adhesive layer, causing the ostomy bag to peel off unexpectedly or causing a continuous pulling sensation in the patient's abdomen, significantly reducing the patient's long-term compliance.

[0006] Regarding the biocompatibility and environmental tolerance of sensors, existing technologies are still limited by the physicochemical properties of traditional electrode materials. For example, CN118574592A discloses an ostomy bag accessory that explicitly uses "inorganic ink containing silver particles" to prepare printed sensors. However, in the complex corrosive environment of high humidity, rich in electrolytes and biological enzymes inside the ostomy bag, such silver, copper, and other metal-based electrodes are prone to electrochemical migration or oxidation reactions, leading to signal baseline drift or even circuit breakage. Furthermore, the precipitation of metal ions in a long-term humid environment significantly increases the risk of contact dermatitis or allergic reactions in patients. More critically, existing technologies lack a dense barrier encapsulation system for flexible devices, which can trap metal ions (such as Ag). + / Cu 2+ If the precipitate in a long-term immersion environment is not blocked by a dense barrier layer, it can easily penetrate through the simple physical film layer to the electrode surface, causing the sensor to fail due to corrosion within 72 hours of wear. This is significantly delayed compared to the 3-7 day clinical replacement cycle of modern ostomy bags, resulting in a waste of medical resources and an increase in patient maintenance costs. Summary of the Invention

[0007] In view of the significant deficiencies of existing technologies in terms of mechanical adaptability, multi-dimensional sensing capabilities, and bioelectronic interface stability, the present invention aims to provide a flexible ostomy bag fluid level-temperature dual-modal monitoring device and method based on liquid metal stress-buffered interconnects. This aims to overcome the contact failure and signal distortion problems of traditional rigid sensors in complex bodily fluid environments while ensuring the flexibility and continuity of the ostomy bag and wearing comfort. Simultaneously, it addresses the clinical pain point that existing single-modal monitoring schemes cannot capture pathological thermodynamic characteristics. The present invention achieves simultaneous and accurate dual-modal sensing of fluid level and temperature within the ostomy bag and fully integrated wireless interaction by constructing a highly conformal sensing front end and a highly reliable rigid-flexible interconnect architecture. Furthermore, it utilizes a long-lasting biocompatible encapsulation system to significantly extend the device's lifespan in complex corrosive environments, thereby meeting the clinical nursing needs for intelligent, all-weather, and precise management of ostomy bags, helping to reduce the risk of ostomy infection, and filling a technological gap in this field.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A flexible ostomy bag level-temperature dual-modal monitoring device based on liquid metal stress-buffered interconnects includes a flexible sensing unit, an FPC integrated control unit, a flexible interconnect structure, and a flexible encapsulation layer, wherein:

[0010] The flexible sensing unit is configured to fit the curved surface of the outer wall of the ostomy bag, including a flexible substrate and interdigitated capacitive electrodes and resistance temperature electrodes disposed on the same plane of the flexible substrate by screen printing process.

[0011] The resistance temperature electrode and the interdigital capacitor electrode are printed in the same layer and located on one side of it. Both the interdigital capacitor electrode and the resistance temperature electrode are in the form of an interdigital array structure.

[0012] The FPC integrated control unit integrates an FPC flexible circuit board and a capacitance detection chip, a main control and wireless communication chip, a flexible battery and a vibration module integrated on the FPC flexible circuit board.

[0013] The capacitance detection chip is used to collect the capacitance change signal of the interdigital capacitor electrodes. The main control chip and the capacitance detection chip communicate via I / O. 2 The C-type digital bus is connected and configured to acquire analog voltage signals across the resistive temperature electrodes; the flexible battery is laid flat on one side of the FPC flexible circuit board; the vibration module is used to provide instant vibration alarm.

[0014] The flexible interconnection structure is located at the electrical connection between the flexible sensing unit and the FPC integrated control unit;

[0015] The flexible interconnect structure uses liquid metal conductive pillars, which are placed between the electrode pins of the flexible sensing unit and the pads of the FPC flexible circuit board to form a suspended liquid stress buffer layer.

[0016] The flexible encapsulation layer covers the outside of the flexible sensing unit and the FPC integrated control unit;

[0017] The device also includes an ostomy bag adapter layer disposed on the bottom surface of the flexible substrate of the flexible sensing unit. The ostomy bag adapter layer is a peelable medical pressure-sensitive adhesive layer configured to provide shear bonding force sufficient to support the weight of the device while allowing for residue-free peeling from the surface of the ostomy bag.

[0018] A method for dual-modal monitoring of liquid level and temperature in a flexible ostomy bag using the above-mentioned device includes the following steps:

[0019] Step S1, Initial Calibration: Based on the characteristics of the interdigital capacitance electrode and the resistance temperature electrode, a mapping model is constructed. The specific steps are as follows:

[0020] Step S1-1: Constructing a liquid level mapping model: Based on the sensing characteristics of the interdigital capacitive electrodes, standard equivalent calibration fluid is sequentially injected into a standard ostomy bag container at preset step sizes. The original capacitance values ​​at different liquid levels are collected, and the least squares method is used for data fitting to establish a linear regression equation between capacitance value and liquid level height.

[0021]

[0022] In the formula: To calculate the liquid level height; The capacitance value is collected in real time. The zero-point capacitance of the system is the sum of the substrate dielectric constant and the parasitic capacitance in the absence of liquid. The capacitance sensitivity coefficient is determined by the electrode structure;

[0023] Step S1-2: Constructing a temperature mapping model: The device is placed in a precision constant-temperature oil bath, and multi-point calibration is performed within the physiological temperature range of 32~42℃. Based on the negative temperature coefficient characteristics of the PEDOT:PSS / MWCNTs nanocomposite material, a linear mapping equation between resistance (R) and temperature (T) is established:

[0024]

[0025] In the formula: To monitor temperature; The reference calibration temperature; This is the real-time resistance value; The resistance value at the reference temperature; The thermal response coefficient of the material;

[0026] Step S2, Adaptor Installation: Using the ostomy bag adapter layer, attach the device to the effective sensing area at the bottom of the outer wall of the ostomy bag body. Specific steps are as follows:

[0027] Step S2-1, Sensing Area Positioning and Surface Pretreatment: Select a flat area on the outer side of the ostomy bag that avoids the rigid sealing area at the bottom as the best sensing area. Use medical alcohol swabs to degrease and clean this area to thoroughly remove any mold release agent oil and dust that may be present on the surface.

[0028] Step S2-2, Bubble-free conformal bonding: Remove the release paper from the ostomy bag adapter layer and align and bond the device along the longitudinal axis of the ostomy bag;

[0029] Step S3, Dual-modal asymmetric sampling: Control the capacitance detection chip to acquire the liquid level signal at the first sampling frequency, and control the main control and wireless communication chip to acquire the temperature signal at the second sampling frequency. The specific steps are as follows:

[0030] Step S3-1, Dynamic monitoring of liquid level: Configure a capacitance detection chip to collect raw capacitance data at a sampling rate of 1 Hz, and use a sliding window average filtering algorithm to perform a weighted average of 5 consecutive sampling points to effectively filter out high-frequency mechanical vibration noise caused by changes in body position, and ensure a smooth and stable output liquid level change curve.

[0031] Step S3-2, Intermittent Temperature Monitoring: The main control and wireless communication chip are configured to periodically wake up the analog-to-digital converter at a frequency of 0.1 Hz. During the sampling window, a short-term voltage excitation is applied to the resistance temperature electrode and the analog voltage signal is acquired. Then, the power supply circuit is immediately cut off. The acquired voltage signal is converted into a resistance value inside the chip and then substituted into a preset temperature mapping model to calculate the real-time temperature value. This strategy eliminates the Joule heating self-heating effect of the resistance electrode at the physical level through an extremely low duty cycle power-on method, ensuring the non-destructive and accurate capture of the temperature of the stoma microenvironment.

[0032] Step S4, Real-time Calculation and Alarm: When the monitored data exceeds the threshold, the vibration module is triggered to activate the vibration alarm. The specific steps are as follows:

[0033] Step S4-1, De-jitter Verification: When the filtered liquid level data or temperature data exceeds the preset threshold, the system immediately interrupts the current low-power sleep strategy and enters the high-frequency verification mode; the sampling frequency of the corresponding abnormal parameter is temporarily increased to 2 to 10 times the normal monitoring frequency (e.g., liquid level sampling is increased to 2 Hz, temperature sampling is increased to 1 Hz), and three consecutive instantaneous data acquisitions are performed; only when all three acquired data exceed the threshold is it determined to be a real abnormality and an alarm is triggered; if any acquired data falls below the threshold, it is determined to be an occasional interference (such as mechanical shaking or instantaneous heat source), and the system automatically resets the counter and returns to the low-power monitoring mode;

[0034] Step S4-2, Tiered Response: Once an abnormality is confirmed, local tactile feedback is immediately triggered, driving the vibration module to emit a 200 Hz vibration to alert the patient; at the same time, the Wi-Fi module is woken up to push an emergency interruption request for "ostomy bag overflow" or "ostomy overheating abnormality" to the user terminal or cloud platform with the highest priority.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] 1. This invention is the first to achieve simultaneous and accurate sensing of both liquid level and temperature in the field of ostomy bag monitoring. Unlike existing technologies, such as CN119950160A, which rely solely on physical deformation or magnetic fields to detect a single liquid level, this invention innovatively integrates a heterogeneous functional electrode array. Utilizing the piezoresistive and dielectric properties of composite materials, the device not only achieves quantitative liquid level monitoring with a resolution of 0.1 mm, but also in-situ temperature monitoring with an accuracy better than ±0.1℃. This dual-modal mechanism not only prevents physical leakage caused by overflow of excrement in real time, but also captures minute fluctuations in the thermodynamic state of the ostomy microenvironment, significantly advancing the infection warning time window and effectively filling the technological gap in existing devices for monitoring pathophysiological indicators.

[0037] 2. This invention solves the problem of "mechanical impedance mismatch" at rigid-flexible interfaces. Addressing the pain points of traditional rigid sensors being prone to detachment and breakage, this invention constructs a fully flexible architecture of nanocomposite thin film + liquid metal interconnect. Thanks to the intrinsic flexibility of PEDOT:PSS and the ultra-thin conformal design of FPC, the device can undergo arbitrary curling deformation with the surface of the ostomy bag. In particular, the introduction of gallium indium tin liquid metal as a dynamic stress buffer layer at the rigid-flexible interface effectively releases the interfacial shear stress. Tests show that even under extreme deformation and cyclic loading with a bending radius of < 5 mm, it can still maintain the integrity of the conductive path and the signal-to-noise ratio of signal transmission, truly achieving a balance between imperceptible wear and dynamic monitoring stability.

[0038] 3. This invention overcomes the environmental tolerance bottleneck of metal-based flexible electrodes. Addressing the complex corrosive environment of high humidity, acid / alkali, and enzymatic degradation within ostomy bags, this invention constructs a functionally graded encapsulation system combining a dense Parylene barrier with a flexible medical-grade silicone buffer. Compared to existing technologies, such as the silver paste electrode in CN118574592A, which is prone to electrochemical migration, this invention's dual-layer encapsulation effectively isolates corrosive ion penetration, extending the device's lifespan to >30 days. This perfectly covers the 3-7 day clinical replacement cycle of ostomy bags, solving the pain points of short lifespan and high maintenance costs of traditional sensors.

[0039] 4. Achieving a performance balance between "edge computing" and "low power consumption," this invention abandons high-computing-power neural network algorithms and adopts a linear regression model combined with an asymmetric sampling strategy (1 Hz for liquid level / 0.1 Hz for temperature). This significantly reduces system power consumption while ensuring real-time monitoring, achieving a long battery life of 72 hours on a single charge. Simultaneously, the integrated 200 Hz vibration tactile feedback and wireless dual-mode communication (Bluetooth / Wi-Fi) construct a closed-loop interactive system of "near-field privacy alarm + remote medical management," greatly improving patient compliance and nursing efficiency.

[0040] 5. Possessing excellent health economics value and universal adaptability, the device adopts a reversible physical adhesion design, achieving non-destructive transfer and recycling between different ostomy bags through a controlled interface adhesion force of 30 J / m². Combined with the intelligent one-click calibration function on a mobile app, it can be adapted to mainstream ostomy bag brands such as Coloplast and Comvid without the need for specialized equipment, demonstrating extremely high clinical promotion value and health economic advantages. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the overall structure of the flexible ostomy bag liquid level-temperature dual-modal monitoring device;

[0042] Figure 2 This is an enlarged schematic diagram of the layered structure of the flexible sensing unit;

[0043] Figure 3 This is a side cross-sectional view of the flexible ostomy bag liquid level-temperature dual-modal monitoring device;

[0044] Figure 4 This is a schematic diagram of the circuit layout of the FPC integrated control unit;

[0045] Figure 5 This is a schematic diagram showing the installation location of the flexible ostomy bag liquid level-temperature dual-modal monitoring device on the ostomy bag;

[0046] Figure 6 This is a flowchart of the workflow for the flexible ostomy bag liquid level-temperature dual-modal monitoring method;

[0047] In the figure, 1 is the flexible ostomy bag liquid level-temperature dual-mode monitoring device, 101 is the outer encapsulation layer, 201 is the inner encapsulation layer, 301 is the FPC flexible circuit board, 302 is the main control and wireless communication chip, 303 is the capacitance detection chip, 304 is the vibration module, 305 is the flexible battery, 306 is the charging interface, 401 is the liquid metal conductive column, 501 is the interdigital capacitor electrode, 502 is the resistance temperature electrode, 503 is the flexible substrate, 601 is the ostomy bag adapter layer, 701 is the ostomy bag body, and 702 is the ostomy connection hole. Detailed Implementation

[0048] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0049] This invention provides a flexible ostomy bag liquid level-temperature dual-modal monitoring device and method based on liquid metal stress buffer interconnection, aiming to solve the following four key technical problems:

[0050] 1. Addressing the issue of inaccurate monitoring due to poor mechanical compatibility: This addresses the technical problem that existing liquid level monitoring devices often employ rigid mechanical structures or discrete hard components, which result in a severe mismatch in Young's modulus with flexible ostomy bag membrane materials. This leads to interface peeling and motion artifacts during bag deformation, resulting in low dynamic monitoring accuracy.

[0051] 2. Addressing the issue of delayed early warning caused by the lack of multidimensional perception: Solving the technical problem that existing technologies lack the ability to synchronously monitor the thermodynamic state of excrement, and cannot capture minute temperature change signals caused by stoma infection or inflammation, resulting in limited clinical early warning functions and delayed intervention.

[0052] 3. Addressing the issues of rigid-flexible interconnect failure and poor wearing experience: Solving the technical problems of low integration of sensors and control modules in existing devices, stress concentration at the interface between rigid circuits and flexible films, which easily leads to mechanical fatigue fracture, and the split redundant design resulting in strong foreign body sensation and low patient compliance.

[0053] 4. Addressing the issue of device corrosion failure in complex bodily fluid environments: Solving the technical problem that traditional metal-based electrodes have insufficient biocompatibility and lack a dense barrier encapsulation system, making them prone to electrochemical migration or corrosion in the high humidity, acid and alkaline, and enzymatic environments of ostomy bags, resulting in the device's service life not matching the clinical replacement cycle of the ostomy bag.

[0054] like Figures 1-5As shown, the flexible ostomy bag level-temperature dual-modal monitoring device based on liquid metal stress-buffered interconnects adopts an integrated hierarchical architecture of "sensing-control-packaging," mainly composed of a flexible sensing unit, an FPC integrated control unit, a flexible interconnect structure, a flexible packaging layer, and an ostomy bag adapter layer. The flexible sensing unit innovatively employs a heterogeneous material integration design: it utilizes conductive silver paste composite material to construct interdigital capacitive electrodes for precise liquid level monitoring, and utilizes PEDOT:PSS / MWCNTs nanocomposite material to construct resistive temperature electrodes for sensitive temperature monitoring; simultaneously, a stress-buffered layer is constructed using liquid metal (EGaIn), achieving fatigue-resistant and reliable interconnection between the flexible sensor and the rigid FPC. The FPC integrated control unit is equipped with an FDC2214 capacitance detection chip and an ESP32 dual-mode communication chip, enabling efficient signal processing and wireless transmission; the inner hydrophobic and outer flexible double-layer packaging system ensures long-term biological stability in complex bodily fluid environments. Furthermore, this invention, combined with an asymmetric sampling strategy, achieves low-power synchronous monitoring of liquid level and temperature, effectively solving the problems of signal interference and connection failure under complex deformation, making it suitable for long-term intelligent care of ostomy bags. The specific structure and connection relationships of each functional module are detailed below:

[0055] 1. Flexible sensing unit: This unit adopts a heterogeneous material hybrid integrated structure, with a flexible substrate 503 as the carrier, and integrates interdigital capacitor electrode 501 and resistance temperature electrode 502 constructed of heterogeneous materials through screen printing process.

[0056] Substrate modification treatment: The flexible substrate 503 is preferably a polyethylene terephthalate (PET) film or a polytetrafluoroethylene (PTFE) film with a thickness of 100~200 μm. The overall size of the flexible substrate 503 is designed to be 12 cm × 12 cm. The printing surface of the flexible substrate 503 undergoes ultraviolet ozone surface modification treatment. Taking PET as an example, in order to solve the adhesion problem of organic conductive inks on hydrophobic PET surfaces, the printing surface of the substrate is modified with ultraviolet ozone (UVO). This treatment introduces polar groups such as hydroxyl (-OH) and carboxyl (-COOH) groups on the substrate surface, reducing the surface water contact angle to <40°, significantly improving the wettability and chemical bonding force between the substrate and the subsequent functional ink interface.

[0057] Liquid level monitoring electrode—interdigital capacitive electrode 501: fabricated using screen printing. The material of interdigital capacitive electrode 501 is flexible conductive silver paste, utilizing its high conductivity as the liquid level sensing medium. To accommodate the high dielectric properties of excrement within the ostomy bag, the electrode is designed as a 4-pair wide-pitch interdigital array structure (IDE). Specific geometric parameters are: width of a single finger strip in the Y-axis direction. =1.0±0.1 cm, length of a single electrode in the X-axis direction =7.00±0.2 cm, distance between adjacent interdigitated fingers =0.1±0.02 cm, thickness of printed film in the Z-axis direction =16.4±1.5 μm.

[0058] Silver paste modified formulation: To balance high conductivity and printability, silver paste is used as the matrix, dimethyl sulfoxide (DMSO) as the conductivity enhancer, and carboxymethyl cellulose (CMC) as the rheology modifier. The silver paste content is 70 wt%, the DMSO content is 5 vol%, and the CMC content is 1 wt%. The rheology modifier is used to adjust the thixotropy of the ink, making its viscosity suitable for the screen printing process, thus ensuring the uniformity of the film thickness and interlayer adhesion of the sensing coating on the flexible substrate. Through adjustment, the thixotropic viscosity of the conductive silver paste is controlled at 150~200 Pa·s to precisely match the shear rate requirements of screen printing.

[0059] Temperature monitoring electrode – Resistance temperature electrode 502: Resistance temperature electrode 502 is printed on the same layer as interdigital capacitor electrode 501 and located on its bottom side. It is designed with an elongated interdigital structure to improve resistance sensitivity. Its geometric dimensions are: width 1.0±0.1 mm, length 5.0±0.2 cm, and thickness 34.6±3.0 μm. The material of resistance temperature electrode 502 is a PEDOT:PSS / MWCNTs nanocomposite material prepared by mixing PEDOT:PSS conductive polymer and multi-walled carbon nanotubes, to utilize its high temperature coefficient of resistance as a temperature sensing medium. In order to obtain excellent temperature coefficient of resistance (TCR), 10 wt% of multi-walled carbon nanotubes (MWCNTs) are doped into PEDOT:PSS conductive polymer. This organic-inorganic hybrid conductive network structure effectively improves the electrode's thermal response characteristics and bending resistance.

[0060] 2. Flexible Interconnect Structure: Addressing the weakness of traditional rigid welding which is prone to breakage under flexible deformation, this invention employs a suspended stress-buffered interconnect architecture based on liquid metal conductive pillars 401. Specifically, utilizing the high surface tension of gallium indium tin alloy (EGaIn), vertical liquid metal conductive pillars 401 are constructed between the electrode pins of the flexible sensing unit and the copper foil pads of the FPC flexible circuit board 301. This structure creates a physical gap between the FPC layer and the underlying sensing layer, thereby constructing a suspended liquid stress-buffered layer. When the device undergoes bending or stretching deformation with the ostomy bag, the liquid metal pillars undergo rheological slippage to absorb interfacial shear stress, achieving mechanical decoupling and reliable electrical connection between the rigid circuit and the flexible substrate.

[0061] 3. FPC Integrated Control Unit: This unit is the core control center of the device, used to collect, process, and wirelessly transmit signals from the flexible sensing unit. For example... Figure 1 , Figure 3 and Figure 4 As shown, the unit uses an FPC flexible circuit board 301 as a carrier and integrates a capacitance detection chip 303, a main control and wireless communication chip 302, a flexible battery 305, and a vibration module 304.

[0062] (1) The hardware carrier is a flexible printed circuit board with a thickness of 0.1~0.2 mm on a polyimide (PI) substrate. The overall size is controlled at 10 cm×3 cm. This size design ensures the integrity of the circuit wiring and adapts to the curvature of the outer wall of the ostomy bag, minimizing the constraint on the flexibility of the bag.

[0063] (2) The capacitance signal acquisition link integrates a capacitance-to-digital converter, preferably the Texas Instruments FDC2214. This chip uses I... 2 The C-band communication bus is electrically connected to the main control chip, and its input pin CH0 is connected to the interdigital capacitor electrode of the flexible sensing unit. The detection range is configured to be 0~1000 pF, with a resolution better than 0.1 pF, and an effective data output rate configured to be 1 Hz. This module utilizes the medium inside the ostomy bag, which is air (with a relative permittivity of...). ) becomes excrement (relative permittivity) The significant change in dielectric constant caused by the liquid level can be used to achieve non-contact quantification of the liquid level height.

[0064] (3) The main control and wireless communication architecture adopts a low-power dual-mode IoT module, preferably the ESP32-DevModule, which integrates Bluetooth 5.0 BLE and Wi-Fi dual-mode communication protocols. The Bluetooth channel is configured in near-field broadcast mode with a transmission distance of 10-20 m, used for real-time low-power data push to the patient's mobile APP; the Wi-Fi channel is configured in remote connection mode, used to upload encrypted data packets to the cloud-based medical management platform when an alarm is triggered. Utilizing the 12-bit resolution analog-to-digital converter (ADC) integrated within the ESP32 chip, a resistance temperature electrode is connected via the GPIO3 pin to collect microvolt-level voltage fluctuations caused by temperature changes in real time and convert them into resistance values. A circular buffer is configured using the chip's built-in 16 MB Flash memory, which can store at least one week's worth of complete monitoring data offline to prevent data loss.

[0065] (4) The flexible energy storage unit is equipped with a customized 3.7 V flexible pouch lithium polymer battery with a capacity of 100 mAh and dimensions of 5 cm × 2 cm × 0.5 cm. The battery has bending stiffness matching the substrate and is stacked with the FPC. The battery voltage is regulated to 3.3 V by a low-dropout linear regulator to provide clean power to the system. Combined with the system's low-power sleep strategy, a single charge can support continuous operation of the device for ≥72 hours.

[0066] (5) The tactile feedback and alarm logic are integrated with a vibration module 304, the core of which is a miniature eccentric rotor motor (ERM) of the preferred model PKG1210D120. The control input terminal of the tactile vibration module 304 is electrically connected to another GPIO pin of the general-purpose input of the main control and wireless communication chip 302. Specifically, the chip outputs a control signal PWM wave through this GPIO pin to control the on / off state of the motor power supply circuit. The ESP32 main control program presets two sets of safety thresholds: liquid level and temperature. When the real-time monitoring data triggers either threshold, the main control and wireless communication chip 302 immediately outputs a drive signal through the GPIO pin to activate the motor to generate mechanical vibration with a frequency of 200 Hz and an amplitude of 0.1 mm. This vibration can penetrate clothing to provide immediate and private tactile feedback, allowing the user to perceive abnormalities without having to check their mobile phone.

[0067] 4. Flexible Encapsulation Layer: Addressing the complex environment inside the ostomy bag, characterized by high humidity (RH>90%), acid and alkali corrosion, and mechanical friction, this invention constructs a heterogeneous dual-layer composite encapsulation structure with an inner dense barrier and an outer flexible buffer. Through the complementary properties of the materials, it balances long-term protection and mechanical compatibility of the device. The flexible encapsulation layer includes an inner encapsulation layer 201 and an outer encapsulation layer 101. The inner encapsulation layer 201 is a dense parylene (Parylene C) film deposited on the surface of the flexible sensing unit and the FPC. The outer encapsulation layer 101 is a medical-grade silicone elastomer coated and cured on the outside of the inner encapsulation layer 201, forming a rounded dome-shaped appearance.

[0068] Inner layer: A dense 10 μm thick parylene C film is grown in situ on the interconnected device surface using vacuum chemical vapor deposition (CVD). Utilizing the strong permeability of the gaseous monomers from CVD, the film ensures 360° conformal coverage of the interdigitated electrode gaps, liquid metal junctions, and FPC cutting edges, forming a pinhole-free dense dielectric barrier. This layer utilizes the extremely low water vapor permeability of Parylene C to cut off water and oxygen channels, fundamentally inhibiting the electrochemical migration and metal dendrite growth of the internal flexible conductive silver paste under continuous voltage, thus solving the short-circuit failure problem of metal-based electrodes mentioned in the background art.

[0069] Outer Layer: A 50 μm thick medical-grade silicone elastomer coating is prepared on the outside of the Parylene layer using a spin-coating process. Dow Corning 734 flowable sealant is preferred. The spin-coating parameters are set as follows: spin speed 1300 rpm, single spin-coating time 15 s, total leveling and curing time 1 min, followed by thermosetting at 60℃. This layer utilizes the low Young's modulus of silicone to construct a mechanical stress buffer zone, effectively absorbing the interfacial shear force generated during random deformation of the ostomy bag, protecting the brittle Parylene layer from breakage. Simultaneously, the high coefficient of friction of the silicone surface provides an anti-slip function, preventing artifacts caused by micro-displacement of the device on the smooth surface of the ostomy bag. Experimental verification shows that after immersion in artificial urine at pH 6.5 for 30 days, the electrical performance retention rate of the internal circuitry is >95%, and its biocompatibility strictly complies with the ISO 10993-5 cytotoxicity standard, ensuring safety for long-term skin contact.

[0070] 5. Ostomy Bag Adaptor Layer 601: A peelable medical-grade pressure-sensitive adhesive is used to detachably attach the device to the outer wall of the ostomy bag body 701. The preferred model is KL-6638AB, coated on the back of the flexible substrate 503, with an adhesive layer thickness controlled at 20 μm. Through formulation optimization, the interfacial adhesion strength of the adhesive layer is adjusted to 30 J / m². This adhesion strength threshold achieves a balance between stable adhesion and non-destructive peeling—ensuring the device does not detach when the bag moves, while allowing the user to easily peel the device without residue or damage to the ostomy bag membrane when changing the ostomy bag or battery. This enables the device to be reused repeatedly, reducing the cost of use for patients.

[0071] Based on the above-mentioned device, this invention proposes an intelligent monitoring method. This method, through a strategy of factory pre-calibration plus dynamic configuration at the user end, combined with a linearization algorithm and asymmetric sampling, achieves low-power, high-precision real-time monitoring. Specifically, it includes the following steps:

[0072] Step 1, Device Initialization and Parameter Calibration Model:

[0073] To eliminate the effects of device manufacturing tolerances (such as differences in printed electrode thickness) and environmental reference drift, an accurate sensor mapping model needs to be established. This step is divided into two stages: factory calibration and power-on self-test.

[0074] Step S1-1, Hardware self-test and benchmark establishment: Power on the device, the main control module ESP32 starts the self-test program, establishes a wireless connection with the host computer calibration system through the Bluetooth low power channel, and confirms that the reference frequency of the FDC2214 capacitor detection module and the reference voltage of the ADC module are within the normal range.

[0075] Step S1-2: Constructing a liquid level mapping model: Based on the sensing characteristics of the silver paste interdigitated electrodes, standard equivalent calibration solution is sequentially injected into a standard ostomy bag container at preset step sizes. The FDC2214 collects the original capacitance values ​​at different liquid levels, and the least squares method is used for data fitting to establish a linear regression equation of capacitance value (C) - liquid level height (H):

[0076]

[0077] In the formula: To calculate the liquid level height; The capacitance value is collected in real time. The zero-point capacitance of the system is the sum of the substrate dielectric constant and the parasitic capacitance in the absence of liquid. The capacitance sensitivity coefficient is determined by the electrode structure.

[0078] Steps S1-3: Constructing a temperature mapping model: Place the device in a precision constant-temperature oil bath and perform multi-point calibration within the physiological temperature range of 32~42℃. Based on the negative temperature coefficient characteristics of the PEDOT:PSS / MWCNTs nanocomposite material, establish a linear mapping equation between resistance (R) and temperature (T):

[0079]

[0080] In the formula: To monitor temperature; The reference calibration temperature; This is the real-time resistance value; The resistance value at the reference temperature; denoted as the thermal response coefficient of the material.

[0081] Steps S1-4: Intelligent Threshold Configuration: The user inputs the specifications of the ostomy bag currently in use (such as capacity and brand) in the mobile APP. Based on the above HC model, the algorithm system automatically calculates the capacitance threshold corresponding to the 80% capacity warning line. and set the temperature alarm threshold The default setting is 38.5℃, the clinical infection warning line. Complete the personalized parameter configuration.

[0082] Step 2: Adaptation and Installation & Interface Coupling Optimization:

[0083] Step S2-1, Sensing Area Positioning and Surface Pretreatment: The optimal sensing area is a flat area on the outer side of the ostomy bag, avoiding the rigid seal at the bottom. Preferred Positioning: In this embodiment, this area is set 2-4 cm above the bottom edge of the ostomy bag, preferably 3 cm. This location selection has dual technical significance: it effectively avoids interference from wrinkles and uneven thickness at the bottom heat-sealed area of ​​the ostomy bag on the capacitive electric field, and ensures that the sensor is located at the beginning of liquid accumulation, enabling it to capture early signals of excrement accumulation.

[0084] Pretreatment: Use medical alcohol wipes to degrease and clean the area to thoroughly remove any mold release agent oil and dust that may be present on the surface, in order to improve the wettability of the adhesive layer.

[0085] Step S2-2, Bubble-free conformal bonding: Remove the release paper from the adapter layer and align the device along the longitudinal axis of the ostomy bag. Application technique: Utilize the viscoelastic rheological properties of the medical pressure-sensitive adhesive, applying even pressure from the center outwards for 20-30 seconds.

[0086] Physical Mechanism: This step aims to use external pressure to force the adhesive layer to flow and fill the microstructure of the ostomy bag surface, completely eliminating interfacial microbubbles. This is due to the relative permittivity of air (ε...). r ≈1) The difference between the excrement and the polymer membrane material is much lower. Eliminating the air gap can build a uniform interface dielectric coupling channel, which physically eliminates the attenuation and interference of series parasitic capacitance on the small liquid level signal, and ensures the signal-to-noise ratio of capacitance measurement.

[0087] Step 3, Dual-modal asymmetric sampling and anomaly detection strategy:

[0088] In response to the differentiated physical characteristics of liquid level signals (high dynamism, susceptibility to interference) and temperature signals (large thermal inertia, slow change) in ostomy bag applications, this system implements a differentiated asymmetric sampling strategy to maximize the reduction of system power consumption and improve measurement accuracy while ensuring real-time monitoring.

[0089] Step S3-1, Dynamic Liquid Level Monitoring: Since patient walking, breathing, or bending over can cause significant sloshing of the liquid inside the bag, resulting in instantaneous capacitance fluctuations, the sampling strategy is as follows: The FDC2214 is configured to collect raw capacitance data at a sampling rate of 1 Hz. Algorithm Processing: The system internally runs a sliding window averaging filter algorithm, with the window size set to... =5. This algorithm performs a weighted average of 5 consecutive sampling points, effectively filtering out high-frequency mechanical vibration noise caused by changes in body position, ensuring a smooth and stable output liquid level change curve.

[0090] Step S3-2, Intermittent Temperature Monitoring: Given the slow change in human body surface temperature and the tendency of resistive sensors to generate Joule heating under continuous power, the sampling strategy is as follows: The main control chip executes monitoring logic with an extremely low duty cycle, waking up the analog-to-digital converter module at a frequency of 0.1 Hz. During the sampling window, a short-term voltage excitation is applied to the resistive temperature electrode to acquire the analog voltage signal, and then the power supply circuit is immediately cut off. The acquired voltage signal is converted into a resistance value inside the chip and then substituted into a preset "resistance-temperature" linear mapping model to calculate the real-time temperature value. Technical Effects: Compared with synchronous high-frequency sampling, this strategy not only reduces ADC computation and RF transmission power consumption by approximately 90%, but more importantly, it effectively suppresses the self-heating effect of the resistive electrode caused by continuous power supply, avoiding positive drift in temperature measurement due to sensor self-heating, and ensuring the accuracy of capturing minute pathological temperature changes.

[0091] Step S3-3, Multi-level Logic Verification and Graded Alarm: To eliminate false alarms caused by occasional interference, the system constructs a software de-jittering and graded response mechanism. De-jittering Verification: When the filtered liquid level or temperature data exceeds a preset threshold, the system does not immediately alarm, but enters a high-frequency verification mode. Only when three consecutive sampled data exceed the threshold is it confirmed as a real anomaly. Graded Response: Once an anomaly is confirmed, the system immediately triggers local tactile feedback, driving a micro motor to emit a 200 Hz vibration to alert the patient; simultaneously, it wakes up the Wi-Fi module and pushes an emergency interruption request for "ostomy bag overflow" or "ostomy overheating abnormality" to the user terminal or cloud platform with the highest priority.

[0092] Step 4: Hierarchical Data Interaction and Cloud Management Strategy

[0093] To address the different needs of home care and telemedicine scenarios, the system constructs a dual-channel data architecture of near-field real-time accompaniment and remote intermittent telemetry.

[0094] Step S4-1, Near-field Interaction Channel: Establish a local link using the ESP32 module's Bluetooth Low Energy protocol. Configured in GATT server mode, the real-time calculated liquid level and temperature values ​​are encapsulated as feature values ​​and synchronized to the patient's mobile app within seconds via the Notify mechanism.

[0095] User value: This channel covers a range of 10-20 meters centered on the patient, allowing the patient to check the status of the ostomy bag at any time and alleviate the panic of the unknown; it also supports OTA firmware upgrades via APP.

[0096] Step S4-2, Remote Medical Channel: Addressing the high power consumption of Wi-Fi, a store-and-forward strategy is implemented. The system caches sampled data in local Flash memory and configures the ESP32 to wake up the Wi-Fi RF front-end at a preset period (preferred every 5-10 minutes). Data Security: The cached historical data packets are hardware encrypted with AES-128 and then burst-transmitted to the cloud-based medical management platform via MQTT or HTTPS protocols. Wi-Fi is then immediately turned off, entering deep sleep mode. Clinical Assistance: The cloud platform automatically generates a 24-hour temperature-liquid level dual-track trend chart based on the uploaded data. Medical staff can use this chart to remotely assess the patient's excretion patterns (such as nighttime excretion) and stoma thermodynamic stability, transforming discrete data into digital biomarkers to provide decision support for personalized care planning.

[0097] Step 5: Modular maintenance and energy management strategy:

[0098] Step S5-1, Device Reuse and "Sacrificial Layer" Transfer Mechanism: Based on the device's device-consumable decoupling design concept, a non-destructive transfer operation is performed when the ostomy bag reaches the end of its service life and needs replacement. Non-destructive peeling: Thanks to the adapter layer being adjusted to a moderate interface energy of 30J / m², users can easily peel the device off the old bag without causing mechanical delamination or breakage of the flexible circuitry. At this point, the old pressure-sensitive adhesive layer is removed as a sacrificial layer. Users only need to attach new replacement medical double-sided tape to the bottom of the device to transfer the high-value intelligent monitoring device to a new ostomy bag for continued use. This design reduces the cost per monitoring session to only the cost of the adhesive consumable, greatly improving the product's economics and promotional potential.

[0099] Step S5-2, Energy Replenishment: When the battery level is below 10%, the APP will push a low battery reminder. Users can charge the battery through the reserved TYPE-C interface. It will be fully charged in about 1.5 hours, supporting the next round of 72 hours of continuous monitoring.

[0100] Example: Fabrication and Performance Verification of Intelligent Monitoring Device

[0101] 1. Fabrication of the flexible sensing unit:

[0102] Substrate Treatment: A medical-grade PET film with dimensions of 12 cm × 12 cm and a thickness of 100 μm was selected as the flexible substrate 503. The substrate was ultrasonically cleaned sequentially in acetone, anhydrous ethanol, and deionized water for 10 min each to remove surface grease and organic impurities. After removal, it was dried in a vacuum oven at 60℃ for 30 min. Subsequently, the dried flexible substrate 503 was surface modified using a Jelight 42-220 UV ozone cleaner for 20 min. Contact angle test results showed that the water contact angle of the treated substrate surface significantly decreased from 70° to 40°, indicating a substantial increase in substrate surface energy, which is beneficial for the wetting and adhesion of subsequent conductive inks.

[0103] Ink preparation: 10 mL of commercially available nano-silver paste (purchased from Shenzhen Yingtai United Technology Co., Ltd., solid content 70-73%) was used as the matrix, and 0.5 mL of DMSO was added as a conductivity enhancer, and 0.1 g of CMC was added as a rheology modifier. The mixture was stirred in a ball mill at 800 rpm for 10 min, followed by ultrasonic dispersion for 20 min to obtain a uniform and thixotropic modified conductive silver paste. Simultaneously, 10 wt% of single-walled carbon nanotubes (SWCNTs) were doped into PEDOT:PSS ink (purchased from MERCK, solid content 5.0 wt%) to prepare a composite thermosensitive ink.

[0104] Screen printing: A 200-mesh custom polyester screen printing plate was used, with the squeegee hardness set to 75 A, printing pressure at 8 N / cm, and printing speed at 40 mm / s. Interdigitated capacitor electrodes 501 (using modified silver paste) and resistance temperature electrodes 502 (using composite thermosensitive ink) with interdigitated structures were printed on a flexible substrate 503. After printing, the electrodes were pre-dried at 60℃ for 5 min, followed by heat annealing at 120℃ for 10 min. The cured electrode film thickness was approximately 5 μm, the conductivity of the interdigitated capacitor electrode 501 reached 200 S / cm, and the temperature coefficient of resistance (TCR) of the resistance temperature electrode 502 remained stable at -0.24% / ℃.

[0105] 2. Assembly of the FPC integrated control unit and liquid metal interconnection:

[0106] Circuit Integration: A 0.1 mm thick PI substrate flexible circuit board is selected as the FPC flexible circuit board 301. A capacitance detection chip 303 (FDC2214), a main control and wireless communication chip 302 (ESP32-C3 module), a vibration module 304 (PKG1210D120 micro vibration motor), and peripheral circuits are mounted on the FPC flexible circuit board 301 using a reflow soldering process; and a 100 mAh flexible battery 305 is connected via a reserved interface.

[0107] Rigid-Flexible Interconnect: To address the connection failure issue between rigid components and flexible substrates during deformation, this embodiment constructs a flexible interconnect structure. Specifically, a small amount of gallium indium tin alloy (EGaIn) is precisely coated at the interface between the pads on the bottom of the FPC flexible circuit board 301 and the electrode pins of the flexible sensing unit below, forming a liquid metal conductive pillar 401. This liquid metal conductive pillar 401 constitutes a soft-hard stress buffer connection layer, ensuring the electrical conductivity of the circuit under bending conditions.

[0108] 3. Functionally graded double-layer encapsulation:

[0109] Inner encapsulation layer fabrication: Using CVD (chemical vapor deposition) technology, an inner encapsulation layer 201 with a thickness of 10 μm is deposited on the surface of the interconnected device. The material selected is a dense Parylene C film to achieve micron-level water and oxygen barrier.

[0110] Outer encapsulation layer preparation: A 50 μm thick layer of medical silicone rubber is spin-coated onto the surface of the inner encapsulation layer 201 and cured at 60°C for 2 hours to form a rounded outer encapsulation layer 101.

[0111] Adaptor layer bonding: A 20 μm thick ostomy bag adapter layer 601 (medical pressure-sensitive adhesive) is bonded to the bottom surface of the flexible substrate 503 to complete the device fabrication.

[0112] 4. Performance Testing and Characterization:

[0113] Liquid level sensing performance: The prepared intelligent monitoring device was attached to the surface of a 500 mL standard ostomy bag via the ostomy bag adapter layer 601. Simulated excrement (0~10 cm height) was injected into the bag at a rate of 1 cm / min. The capacitance value collected by the capacitance detection chip 303 showed good linear change in the range of 0~150 pF.

[0114] Temperature sensing performance: When the device is placed in a precision constant temperature bath at 32~42℃, the resistance value collected by the main control and wireless communication chip 302 decreases linearly in the range of 1200~2800 Ω, and the response is rapid.

[0115] Mechanical reliability verification: The device was subjected to 1000 cyclic bending tests under extreme conditions with a curvature radius of 1 mm. The results showed that the electrode resistance change rate was <8% and the capacitance signal fluctuation was <5%, strongly demonstrating that the interconnect structure based on liquid metal conductive pillars 401 has excellent fatigue resistance characteristics.

[0116] Biocompatibility: In vitro cytotoxicity tests were conducted according to ISO 10993-5 standard. After co-culturing L929 mouse fibroblasts with the device extract for 24 h, the cell survival rate reached 96%, and the rating was non-cytotoxic.

[0117] Communication performance: The measured stable Bluetooth transmission distance reached 20 m with a packet loss rate of <1%; the Wi-Fi data upload rate was stable at 1 Mbps with a cloud synchronization latency of <1 s.

[0118] 5. Clinical application verification:

[0119] Ten colostomy patients were selected as volunteers. After signing informed consent, they wore the device for continuous monitoring for 72 hours. All subjects reported "no obvious foreign body sensation," and the device did not shift or fall off during walking, bending over, or sleeping.

[0120] Monitoring accuracy: The average error between the liquid level data uploaded by the device and the manually calibrated measurement value is ±3%; the average error between the temperature data and the infrared thermometer is ±0.2℃.

[0121] Alarm response: The liquid level threshold is set to 8 cm. When the excrement accumulates to this height, the vibration module 304 triggers a vibration alarm. The response time difference between the alarm and the push notification from the mobile APP is less than 1 second, with an accuracy of 100%.

[0122] Clinical value case: During the trial, a subject developed mild inflammation around the stoma due to improper diet. The device sensitively detected that the local temperature inside the ostomy bag rose to 38.7°C and triggered a temperature alarm. Based on this, medical staff intervened in time to prevent the infection from worsening.

[0123] Battery life: After 72 hours of continuous monitoring, the remaining power of the flexible 305 batteries in all test devices was more than 30%, which fully meets the clinical replacement cycle requirement of 3 to 5 days.

Claims

1. A flexible ostomy bag liquid level-temperature dual-modal monitoring device based on liquid metal stress buffer interconnection, characterized in that... The monitoring device includes a flexible sensing unit, an FPC integrated control unit, a flexible interconnect structure, and a flexible packaging layer, wherein: The flexible sensing unit includes a flexible substrate and interdigitated capacitive electrodes and resistance temperature electrodes disposed on the same plane of the flexible substrate by screen printing process. The resistance temperature electrode and the interdigitated capacitor electrode are printed in the same layer and located on one side of it; The FPC integrated control unit integrates an FPC flexible circuit board and a capacitance detection chip, a main control and wireless communication chip, a flexible battery and a vibration module integrated on the FPC flexible circuit board. The capacitance detection chip is used to collect the capacitance change signal of the interdigital capacitor electrodes. The main control chip and the capacitance detection chip communicate via I / O. 2 The C-type digital bus is connected and configured to acquire analog voltage signals across the resistive temperature electrodes; the flexible battery is laid flat on one side of the FPC flexible circuit board; the vibration module is used to provide instant vibration alarm. The flexible interconnection structure is located at the electrical connection between the flexible sensing unit and the FPC integrated control unit; The flexible encapsulation layer covers the outside of the flexible sensing unit and the FPC integrated control unit; The ostomy bag adapter layer is disposed on the bottom surface of the flexible substrate of the flexible sensing unit.

2. The flexible ostomy bag level-temperature dual-modal monitoring device based on liquid metal stress buffer interconnection according to claim 1, characterized in that... The flexible substrate is a polyethylene terephthalate film or a polytetrafluoroethylene film with a thickness of 100~200 μm. The printing surface of the flexible substrate is treated with ultraviolet ozone surface modification. The interdigital capacitor electrode is made of flexible conductive silver paste, and the electrode is designed as a 4-pair wide-pitch interdigital array structure. The resistance temperature electrode is designed with a long strip interdigitated structure and is made of PEDOT:PSS / MWCNTs nanocomposite material, which is prepared by mixing PEDOT:PSS conductive polymer and multi-walled carbon nanotubes.

3. The flexible ostomy bag level-temperature dual-modal monitoring device based on liquid metal stress buffer interconnection according to claim 1, characterized in that... The flexible interconnect structure uses liquid metal conductive pillars, which are placed between the electrode pins of the flexible sensing unit and the pads of the FPC flexible circuit board to form a suspended liquid stress buffer layer.

4. The flexible ostomy bag level-temperature dual-modal monitoring device based on liquid metal stress buffer interconnection according to claim 1, characterized in that... The FPC flexible circuit board is made of polyimide substrate with a thickness of 0.1~0.2 mm; the capacitance detection chip is an FDC2214 chip, which is connected via I... 2 The C-channel communication bus is electrically connected to the main control chip, and its input pin CH0 is connected to the interdigital capacitor electrode of the flexible sensing unit. The main control and wireless communication chip is an ESP32 chip, and the 12-bit resolution analog-to-digital converter integrated in the ESP32 chip is connected to the resistance temperature electrode through the GPIO3 pin. The flexible encapsulation layer includes an inner encapsulation layer and an outer encapsulation layer. The inner encapsulation layer is a dense film of parylene deposited on the surface of the flexible sensing unit and FPC, and the outer encapsulation layer is a medical-grade silicone elastomer coated and cured on the outside of the inner encapsulation layer.

5. The flexible ostomy bag level-temperature dual-modal monitoring device based on liquid metal stress buffer interconnection according to claim 1, characterized in that... The device also includes an ostomy bag adapter layer, which is made of peelable medical-grade pressure-sensitive adhesive.

6. A method for dual-modal monitoring of liquid level and temperature in a flexible ostomy bag using the device described in any one of claims 1-5, characterized in that... The method includes the following steps: Step S1, Initial Calibration: Based on the characteristics of the interdigital capacitor electrode and the resistance temperature electrode, a mapping model is constructed; Step S2, Adaptation and Installation: Attach the device to the effective sensing area at the bottom of the outer wall of the ostomy bag; Step S3, Dual-modal asymmetric sampling: Control the capacitance detection chip to collect the liquid level signal at the first sampling frequency, and control the main control and wireless communication chip to collect the temperature signal at the second sampling frequency; Step S4, Real-time calculation and alarm: When the monitored data exceeds the threshold, the vibration module is triggered to alarm.

7. The method for dual-modal monitoring of liquid level and temperature in a flexible ostomy bag according to claim 6, characterized in that... The specific steps of step S1 are as follows: Step S1-1: Constructing a liquid level mapping model: Based on the sensing characteristics of the interdigital capacitive electrodes, standard equivalent calibration fluid is sequentially injected into a standard ostomy bag container at preset step sizes. The original capacitance values ​​at different liquid levels are collected, and the least squares method is used for data fitting to establish a linear regression equation between capacitance value and liquid level height. In the formula: To calculate the liquid level height; The capacitance value is collected in real time. The zero-point capacitance of the system is the sum of the substrate dielectric constant and the parasitic capacitance in the absence of liquid. The capacitance sensitivity coefficient is determined by the electrode structure; Step S1-2: Constructing a temperature mapping model: The device is placed in a precision constant-temperature oil bath, and multi-point calibration is performed within the physiological temperature range of 32~42℃. Based on the negative temperature coefficient characteristics of the PEDOT:PSS / MWCNTs nanocomposite material, a linear mapping equation between resistance and temperature is established: In the formula: To monitor temperature; The reference calibration temperature; This is the real-time resistance value; The resistance value at the reference temperature; denoted as the thermal response coefficient of the material.

8. The method for dual-modal monitoring of liquid level and temperature in a flexible ostomy bag according to claim 6, characterized in that... The specific steps of step S2 are as follows: Step S2-1, Sensing Area Positioning and Surface Pretreatment: Select a flat area on the outer side of the ostomy bag that avoids the rigid sealing area at the bottom as the best sensing area. Use medical alcohol swabs to degrease and clean this area to thoroughly remove the release agent oil and dust on the surface. Step S2-2, Bubble-free conformal bonding: Align and bond the device along the longitudinal axis of the ostomy bag.

9. The method for dual-modal monitoring of liquid level and temperature in a flexible ostomy bag according to claim 6, characterized in that... The specific steps of step S3 are as follows: Step S3-1, Dynamic monitoring of liquid level: Configure a capacitance detection chip to collect raw capacitance data at a sampling rate of 1 Hz, and use a sliding window average filtering algorithm to perform a weighted average of 5 consecutive sampling points; Step S3-2, Intermittent Temperature Monitoring: Configure the main control and wireless communication chip to periodically wake up the analog-to-digital converter at a frequency of 0.1 Hz. During the sampling window, apply a short-time voltage excitation to the resistance temperature electrode and collect the analog voltage signal, and then immediately cut off the power supply circuit. After the collected voltage signal is converted into a resistance value inside the chip, it is substituted into the preset temperature mapping model to calculate the real-time temperature value.

10. The method for dual-modal monitoring of liquid level and temperature in a flexible ostomy bag according to claim 6, characterized in that... The specific steps of step S4 are as follows: Step S4-1, De-jitter Verification: When the filtered liquid level data or temperature data exceeds the preset threshold, the system immediately interrupts the current low-power sleep strategy and enters the high-frequency verification mode; the sampling frequency of the corresponding abnormal parameter is temporarily increased to 2 to 10 times the normal monitoring frequency, and three consecutive instantaneous data acquisitions are performed; only when the data acquired in these three acquisitions all exceed the threshold is it determined to be a real abnormality and an alarm is triggered; if any acquisition data falls below the threshold, it is determined to be an occasional interference, and the system automatically resets the counter and returns to the low-power monitoring mode. Step S4-2, Tiered Response: Once an abnormality is confirmed, local tactile feedback is immediately triggered, driving the vibration module to emit a 200Hz vibration to alert the patient; at the same time, the Wi-Fi module is woken up to push an emergency interruption request for "ostomy bag overflow" or "ostomy overheating abnormality" to the user terminal or cloud platform with the highest priority.

Images