A fetal heart monitoring sensor device and method of manufacture, and a fetal heart monitoring method

Abstract

The application provides a fetal heart monitoring sensing device and manufacturing method and a fetal heart monitoring method, and relates to the technical field of medical devices, and specifically discloses a fetal heart monitoring sensing device and manufacturing method and a fetal heart monitoring method.

Description

Technical Field

[0001] This invention relates to the field of wearable sensing devices, and more particularly to a fetal heart rate monitoring sensing device and manufacturing method, as well as a fetal heart rate monitoring method. Background Technology

[0002] Perinatal fetal monitoring currently relies primarily on electronic cardiac heart rate monitoring (CTG), which uses Doppler ultrasound to acquire fetal heart rate and combines it with uterine contraction monitoring for comprehensive assessment. While CTG is widely used, it still has the following problems: Difficulty in long-term continuous home monitoring: Traditional CTG relies heavily on large hospital equipment and requires professional operation, making it unsuitable for long-term, low-cost, non-invasive continuous monitoring by pregnant women at home. Poor interpretation consistency and high false positive rate: CTG images are greatly influenced by operator experience, leading to poor interpretation consistency among different doctors and a high likelihood of false positive alarms.

[0003] In existing non-invasive fetal heart rate monitoring (CTG) methods, besides Doppler ultrasound, there are also methods based on abdominal wall fetal phonocardiography (fPCG) or abdominal wall fetal electrocardiography (fECG). In recent years, non-invasive fetal phonocardiography (fPCG) and fetal electrocardiography (fECG) have been considered important supplements to CTG. Fetal phonocardiography is a passive acoustic signal, safe, radiation-free, and low-cost, and can reflect mechanical activity (S1 / S2, murmurs, etc.); fetal electrocardiography provides the timing "gold standard" R peak of cardiac electrical activity. However, existing sensor solutions based on fPCG or fECG still have significant shortcomings: single-point sensor placement results in weak resistance to changes in fetal position; sensitivity to changes in fetal position makes single-point probes prone to failure; and the dynamic changes in fetal position with gestational age necessitate repeated movement of traditional single-point ultrasound probes to locate the signal, leading to a poor user experience. Most fPCG / fECG acquisition devices employ a single-point or limited-point layout. When the fetal position shifts, the fetal back turns, or the pregnant woman's position changes, the signal amplitude fluctuates significantly, making signal interruption likely. To reduce the complexity of wearing the device, some solutions use a limited-point layout (e.g., single-point / dual-point / triple-point sensor arrangement) or form a differential measurement channel with a small number of electrodes. These solutions share the following characteristics: a small number of sensors, limited coverage, and reliance on single-point or limited-point acquisition of effective fetal heart rate signals.

[0004] It is evident that traditional monitoring devices with single-point or limited-point layouts suffer from problems such as significant signal amplitude fluctuations and signal interruptions when the fetal position shifts, the fetal back turns, or the pregnant woman's position changes. These devices are also prone to failure in continuous wear scenarios.

[0005] Therefore, developing a new fetal heart rate monitoring sensor that can effectively address the impact of fetal position drift and changes in wearing status on monitoring results has become an urgent technical problem to be solved. Summary of the Invention

[0006] To address the aforementioned technical deficiencies, this invention provides a fetal heart rate monitoring sensor device and manufacturing method, as well as a fetal heart rate monitoring method. At the structural level, it solves the problem of failure of single-point or small-point layout schemes based on traditional monitoring sensor devices in continuous wear scenarios.

[0007] This invention provides a fetal heart rate monitoring sensor, comprising:

[0008] A flexible substrate includes: a central region, an arm-shaped connecting region, and a plurality of radiating regions connected to the central region through the arm-shaped connecting region;

[0009] The central control unit is located in the central area;

[0010] A conductive connection structure disposed in the arm-shaped connection region;

[0011] A plurality of fetal heart rate sensing subunits are respectively disposed on each of the radiation zones; each of the fetal heart rate sensing subunits is electrically connected to the central control unit through the conductive connection structure; each of the fetal heart rate sensing subunits includes:

[0012] An acoustic sensing module includes a semi-enclosed acoustic cavity base and a pickup unit; the pickup unit is placed on the bottom surface inside the semi-enclosed acoustic cavity base; the acoustic sensing module is used to collect fetal heart sound signals.

[0013] A ring-shaped fetal heart rate electrode module is used to acquire fetal heart rate electrical signals; the ring-shaped fetal heart rate electrode module is arranged coaxially around the central axis of the pickup unit so that the fetal heart rate sensing subunit performs co-position acquisition of the fetal heart rate sound signal and the fetal heart rate electrical signal.

[0014] An insulating and isolating structure is located between the pickup unit and the annular fetal heart electrode module;

[0015] An elastic vibration isolation structure is disposed between the annular fetal heart electrode and the side wall of the semi-enclosed acoustic cavity base, and its hardness is lower than that of the acoustic cavity base and the annular fetal heart electrode module.

[0016] The central control unit is used to acquire the corresponding fetal heart sound signals and fetal electrical signals in each radiation zone; and to calculate the value of the uterine contraction index using each set of fetal heart sound signals and fetal electrical signals.

[0017] Optionally, the elastic vibration isolation structure is a ring-shaped elastic vibration isolation structure;

[0018] The thickness of the pickup unit, the insulating isolation structure, the annular fetal heart electrode module, and the elastic vibration isolation structure decreases radially in a stepped manner from the center outwards.

[0019] Optionally, the flexible substrate is a star-shaped flexible substrate, and the radiation areas are arranged in a star-shaped array around the central area, so that after fabrication, each of the fetal heart sensing sub-units is arranged in a star-shaped array around the central control unit.

[0020] Optionally, the number of fetal heart rate sensing subunits is 4 to 8.

[0021] Optionally, the arm-shaped connection area is provided with multiple connection points for fetal heart rate sensing subunits; the fetal heart rate sensing subunits are detachably connected to the corresponding connection points; each connection point is adapted to the fetal heart rate position at different gestational weeks.

[0022] Optionally, the flexible substrate includes: a radiating region connected to the central region via at least seven arm-shaped connecting regions; each arm-shaped connecting region connects to at least two of the radiating regions; and the fetal heart rate sensing subunit is disposed on each of the radiating regions.

[0023] The central control unit is used to distinguish different fetal heart sounds based on the relative amplitude and temporal characteristics of the detection signals from each fetal heart sensing subunit, so as to perform multiple pregnancy monitoring; the detection signals include fetal electrocardiogram signals and fetal heart sound signals.

[0024] Optionally, a temperature sensing module and a pressure sensing module are provided around each fetal heart rate sensing subunit; the temperature sensing module is used to detect the local skin temperature; the pressure sensing module is used to detect the contact pressure of the fetal heart rate sensing subunit on the skin.

[0025] The central control unit is used to periodically collect the local skin temperature and the contact pressure, and to evaluate the adhesion quality based on the local skin temperature and the contact pressure, as well as the contact pressure adhesion threshold and the temperature fluctuation threshold.

[0026] If the contact pressure is lower than the contact pressure adhesion threshold and the temperature fluctuation is greater than the temperature fluctuation threshold, it is determined that the adhesion at the fetal heart rate sensing subunit is poor; otherwise, it is determined that the adhesion meets the monitoring requirements.

[0027] This invention provides a method for manufacturing a fetal heart rate monitoring sensor, used to prepare a monitoring sensor as described in any of the preceding claims of this invention, the method comprising:

[0028] A flexible substrate is prepared; each radiation region of the flexible substrate forms a semi-enclosed acoustic cavity base that carries the fetal heart rate sensing subunit, and an acoustic cavity is formed inside it;

[0029] A pickup unit is formed at the center of the semi-enclosed acoustic cavity base;

[0030] Using the central axis of the pickup unit as a reference and employing coaxial positioning technology, a ring-shaped fetal heart electrode module is formed on the semi-enclosed acoustic cavity base, and an insulation area is reserved between the pickup unit and the ring-shaped fetal heart electrode module.

[0031] An insulating isolation structure is formed in the insulating region;

[0032] An elastic vibration isolation structure is formed between the annular fetal heart electrode module and the semi-enclosed acoustic cavity base; the stiffness of the elastic vibration isolation structure is less than that of the acoustic cavity base and the annular fetal heart electrode module.

[0033] Each of the fetal heart rate sensing subunits is connected to a conductive connection structure, and the conductive connection structure is installed in the arm-shaped connection area of ​​the flexible substrate, and the central control unit is installed in the central area of ​​the flexible substrate.

[0034] The present invention also provides a fetal heart rate monitoring method, applied to the fetal heart rate monitoring sensing device as described in any of the preceding claims, the monitoring method comprising:

[0035] The acoustic sensing module and the annular fetal heart electrode module of each of the fetal heart sensing subunits respectively collect the fetal heart sound signal and the fetal heart electrical signal;

[0036] The central control unit acquires the corresponding fetal heart sound signals and fetal heart electrical signals in each radiation zone;

[0037] The values ​​of uterine contraction indices were calculated using the fetal heart sound signals and fetal electrical signals of each group.

[0038] Optionally, the step of calculating the value of the uterine contraction index using each group of fetal heart sound signals and fetal electrocardiogram signals specifically includes:

[0039] Calculate the signal quality index of each group of fetal heart sound signals and fetal electrocardiogram signals, and perform channel selection or weighted fusion to obtain each group of robust fetal heart sound signals and robust fetal electrocardiogram signals;

[0040] Time-series alignment was performed on each group of robust fetal heart sound signals and robust fetal electrocardiogram signals to obtain the preprocessed fetal heart sound signals and fetal electrocardiogram signals for each group.

[0041] The values ​​of the uterine contraction index are calculated using the preprocessed fetal heart rate signals and fetal electrical signals of each group.

[0042] Compared with existing technologies, the above technical solution has the following advantages:

[0043] 1. The structural design addresses the issue of some placement schemes failing in continuous wear scenarios due to changes in fetal position and motion artifacts.

[0044] 2. By using a structural combination with a stepped decrease in thickness, the stress between the elastic vibration isolation structure and the base of the radiation zone gradually changes from large to small, effectively absorbing shear and impact, reducing frictional noise and structural resonance caused by body motion, thereby improving the periodic consistency of the PCG waveform and the detectability of key features (such as S1 / S2).

[0045] 3. The star-shaped array distribution offers higher spatial coverage compared to a scattered multi-point layout, widening the effective signal window. This significantly increases the probability that at least one or more points remain within the relatively effective window at any given time, even with changes in fetal / body position (improved stability / continuity). This allows the central control unit to select or fuse channels based on quality indicators, thus addressing changes in fetal position and wearing status. This significantly improves the data acquisition success rate. Attached Figure Description

[0046] Figure 1 A real-life image showing the installation of a fetal heart rate monitoring sensor on the skin of a pregnant woman in accordance with an embodiment of the present invention;

[0047] Figure 2 and Figure 3 for Figure 1 Schematic diagrams from different angles of the vibration isolation step structure of the fetal heart rate monitoring sensor subunit in the radiation zone of the fetal heart rate monitoring sensor device;

[0048] Figure 4 for Figure 1 A schematic diagram of the central control unit structure in the central area of ​​the fetal heart rate monitoring sensor device;

[0049] Figure 5 An exploded view of the internal structure of a fetal heart rate monitoring sensor subunit of a fetal heart rate monitoring sensor device according to an embodiment of the present invention;

[0050] Figure 6 A schematic diagram showing the distribution of connection points for different pre-reserved connection points during pregnancy in accordance with an embodiment of the present invention;

[0051] Figure 7 A schematic flowchart illustrating a method for manufacturing a fetal heart rate monitoring sensor according to an embodiment of the present invention;

[0052] Figure 8 A flowchart illustrating a fetal heart rate monitoring method according to an embodiment of the present invention.

[0053] Figure label:

[0054] 1-Central Area;

[0055] 10-Central control unit;

[0056] 2-Radiation zone;

[0057] 20 - Fetal heart rate sensing subunit;

[0058] 201-Acoustic Sensing Module;

[0059] 202-Circular Fetal Heart Electrode Module;

[0060] 203 - Insulation and isolation structure;

[0061] 204 - Elastic vibration isolation structure;

[0062] 205 - Top Protective Cover;

[0063] 206 - Semi-enclosed acoustic cavity base;

[0064] 3-Arm-shaped connecting region;

[0065] 30 - Connection point. Detailed Implementation

[0066] The advantages of the present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments.

[0067] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0068] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0069] In the description of this invention, it should be understood that the terms "inner" and "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0070] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. The specific meaning of the above terms should be understood according to the specific circumstances.

[0071] In the following description, suffixes such as "module," "part," or "unit" used to denote elements are used only for the convenience of the description of the invention and have no specific meaning in themselves. Therefore, "module" and "part" can be used interchangeably.

[0072] There are still significant shortcomings in existing sensor solutions based on fPCG or fECG: the sensors are arranged at a single point and have weak resistance to changes in fetal position. Most fPCG / fECG acquisition devices use a single point or a small number of points. When the fetal position shifts, the fetal back turns, or the pregnant woman's position changes, the signal amplitude fluctuates significantly and is prone to signal interruption.

[0073] To address the aforementioned issues, this invention proposes an overall solution of "multi-point array coverage + coaxial acoustic-electric integrated subunit + vibration isolation / hardness gradient + flexible fit" to achieve highly robust and continuously wearable fetal heart rate multimodal monitoring.

[0074] This invention is based on a systematic analysis of the failure mechanism of a few-point layout scheme in continuous wear scenarios. The failure of the few-point layout is not simply caused by "insufficient number of sensors", but by the combined effect of "drift of the effective pickup area caused by changes in fetal position" and "signal quality fluctuation caused by motion artifacts", which makes the single-point / few-point channels lack redundancy and adaptive selection capability.

[0075] Based on the above findings, this application first proposes to replace single-point dependence with array coverage: by constructing a multi-point distribution on a flexible substrate, at any given time there are at least one or more points in a relatively effective window, and channels can be selected or merged according to quality indicators, thereby addressing fetal position drift and changes in wearing status.

[0076] Furthermore, in response to the problems of asynchronous acoustic and electrical signals and complex alignment in traditional "multi-point but acoustic-electrical separation" schemes, this application proposes to construct co-located and coaxial acoustic-electrical integrated acquisition units at each array point, so that heart sounds and electrocardiogram signals can be acquired synchronously in the same local area, thereby reducing the timing deviation caused by spatial path differences from the source and improving the stability of fusion and alignment.

[0077] Meanwhile, heart sound acquisition relies more on mechanical coupling, while electrocardiogram acquisition relies more on stable contact impedance. The structural requirements of the two conflict. Therefore, insulation isolation, independent acoustic cavity and electrode support layer, and elastic vibration isolation structure are further introduced to achieve synergy and decoupling between the shear motion sensitive part of the acoustic channel and the electrode contact stability requirements in the structure, thereby reducing the combined impact of pressure changes and shear noise on the two types of signals.

[0078] Based on the above evolution, the present invention adopts a multi-point array coverage of a star-shaped multi-arm flexible substrate, and forms a co-located and coaxial acoustic-electric integrated sub-unit at each point. It further combines insulation isolation, independent acoustic cavity and electrode support layer, and elastic vibration isolation / step hardness gradient structure to achieve robust acquisition and stable fit of tire position changes and motion artifacts, thereby improving the reliability and availability of continuous monitoring.

[0079] The failure of limited-point placement solutions in continuous wear scenarios presents a challenge due to unclear causes. Traditional solutions have never addressed this issue with a synergistic structure: coaxial geometric constraints + ring electrodes around the acoustic center + insulating layer + independent acoustic cavity and electrode support layer + elastic vibration isolation / stiffness gradient. Existing technologies only suggest separating or closely arranging acoustic sensors and electrodes to avoid interference caused by structural / material / pressure coupling; however, this approach is ineffective and typically requires algorithmic compensation. In fetal monitoring, acoustic propagation delay and its drift with pressure, posture, and fit mean that algorithms alone require continuous estimation and calibration with limited robustness. Therefore, traditional solutions cannot simultaneously ensure stable PCG (Phonocardiography) pickup and ECG (Electrocardiography) contact impedance during dynamic abdominal wear.

[0080] This application not only analyzes the failure mechanism of a few-point layout scheme in continuous wear scenarios, finding that the failure is caused by changes in fetal position and motion artifacts; but also proposes a coaxial hardware structure to reduce spatial path differences and dynamic drift at the source. Furthermore, through a combined design of sensing, vibration isolation, and insulating stepped structures, it resolves the structural contradiction between PCG mechanical coupling and ECG electrical contact, achieving structural coordination and decoupling between the acoustic channel's shear-sensitive parts and the electrode contact stability requirements. This reduces the combined impact of pressure changes and shear noise on both types of signals, significantly reducing algorithm alignment complexity and improving continuous monitoring stability. Repeated experiments, analyses, and demonstrations have shown that the above-mentioned technical solution of this invention has a significant effect on simultaneously ensuring stable PCG pickup and ECG contact impedance during dynamic abdominal wear.

[0081] The invention will now be described in detail with reference to specific embodiments.

[0082] Figure 1 The image shows a real-world illustration of a fetal heart rate monitoring sensor installed on the skin of a pregnant woman in the fetal position, according to an embodiment of the present invention. Figure 2 , Figure 3 , Figure 4 They are respectively Figure 1 A schematic diagram of the structure of the fetal heart rate monitoring sensor device with different angle radiation zones, and the central control unit of the central zone 1. Figure 5 An exploded view of the internal structure of the fetal heart rate sensing subunit of a fetal heart rate monitoring sensing device according to an embodiment of the present invention.

[0083] exist Figure 1 Based on, and in conjunction with reference Figures 2-5 The fetal heart rate monitoring sensor includes: a flexible substrate, a central control unit 10, a fetal heart rate sensing subunit 20, and a conductive connection structure.

[0084] A flexible substrate includes: a central region 1, an arm-shaped connecting region 3, and a plurality of radiating regions 2 connected to the central region 1 through the arm-shaped connecting region 3; a central control unit 10 disposed in the central region 1; a conductive connection structure disposed in the arm-shaped connecting region 3; a plurality of fetal heart rate sensing sub-units 20 respectively disposed on each of the radiating regions 2; and each of the fetal heart rate sensing sub-units 20 being electrically connected to the central control unit 10 through the conductive connection structure.

[0085] Each of the aforementioned fetal heart rate sensing subunits 20 includes: a semi-enclosed acoustic cavity base 206, an acoustic sensing module 201, an insulating isolation structure 203, a ring-shaped fetal heart rate electrode module 202, and an elastic vibration isolation structure 204. The acoustic sensing module 201 includes the semi-enclosed acoustic cavity base 206 and a pickup unit. The pickup unit is located on the inner bottom surface of the semi-enclosed acoustic cavity base; the acoustic sensing module 201 is used to collect fetal heart rate sounds. Optionally, a top protective cover 205 is also included, assembled together with the semi-enclosed acoustic cavity base 206, with an internal cavity for accommodating the fetal heart rate sensing subunit 20. The ring-shaped fetal heart rate electrode module 202 is used to collect fetal heart rate electrical signals. The ring-shaped fetal heart rate electrode module 202 is coaxially arranged around the central axis of the pickup unit, so that the fetal heart rate sensing subunit 20 performs co-location acquisition of the fetal heart rate sounds and the fetal heart rate electrical signals. The insulating isolation structure 203 is located between the pickup unit and the annular fetal heart rate electrode module 202; it is used to prevent the electrical channel from being affected by the acoustic structure. The elastic vibration isolation structure 204 is disposed between the annular fetal heart rate electrode and the side wall of the semi-enclosed acoustic cavity base, and its hardness is lower than that of the acoustic cavity base and the annular fetal heart rate electrode module 202. The central control unit 10 is used to acquire the corresponding fetal heart rate sound signals and fetal heart rate electrical signals in each radiation zone 2; and to calculate the value of the uterine contraction index using each set of fetal heart rate sound signals and fetal heart rate electrical signals. It outputs uterine contraction-related indicators or alarms. Uterine contraction indicators include outputting fetal heart rate (FHR), HRV, etc.

[0086] In real-world continuous wear scenarios, fetal position changes with gestational age / body position, and the pregnant woman's breathing, body movements, and relative slippage of the abdominal skin introduce significant motion artifacts. In this invention, firstly, by arranging the pickup unit and the ring-shaped fetal heart rate electrode module around the same central axis, ensuring spatial consistency and aligning the acoustic propagation path with the electrical conduction path, both types of sensing modules achieve physical co-location of data acquisition. This almost eliminates the propagation delay difference between S1 / S2 and the R peak, enabling co-location acquisition of fetal heart sound and fetal electrocardiogram signals. This objectively simplifies algorithm registration, reduces the difficulty of time registration on the algorithm side, and makes timing alignment simpler and more robust. It solves the problem of complex timing alignment and fusion processing, which reduces algorithm robustness, caused by heart sounds and electrocardiograms being acquired by sensors at different locations, different acoustic propagation paths and electrical conduction paths, and the superimposed changes in skin contact state. This reduces spatial path differences and dynamic drift of the signals from the source.

[0087] Secondly, the present invention designs a pickup unit, a ring-shaped fetal heart electrode module, an insulating isolation structure located between the pickup unit and the ring-shaped fetal heart electrode module, and a low-hardness elastic vibration isolation structure set between the ring-shaped fetal heart electrode and the acoustic cavity base, forming a mechanical-electrical coupling / decoupling collaborative structure: realizing the collaborative optimization of mechanical and electrical coupling.

[0088] Fetal heart rate monitoring requires good acoustic coupling, while fetal electrocardiogram (ECG) requires stable skin contact resistance. Traditional simple superposition schemes of these two technologies have high pickup structure rigidity, easily introducing shear noise. Furthermore, uneven pressure applied to the skin by the ring electrode can cause fluctuations in electrical contact impedance due to fetal movement or the pregnant woman's walking. Gel drying and skin perspiration significantly reduce comfort and signal stability. Therefore, achieving synergistic optimization of mechanical and electrical coupling is difficult.

[0089] In this design of the present invention, through the elastic vibration isolation structure, the high-rigidity pickup unit, the insulating isolation structure, the annular tire heart electrode, the partitioned hardness stepped structure design of the acoustic cavity base, the acoustic sensing module can achieve stable acoustic coupling without introducing strong shear noise due to excessive local pressure. This suppresses the influence of pressure changes / shear motion on acoustic shear noise and skin contact impedance fluctuations (this suppression includes resistance to motion artifacts and impedance drift). The acoustic channel's shear motion-sensitive parts and the electrode contact stability requirements are structurally coordinated and decoupled, reducing the combined impact of pressure changes and shear noise on both types of signals. Simultaneously, the annular electrode achieves a uniform pressure distribution, reducing contact impedance fluctuations.

[0090] This invention provides a fetal heart rate monitoring sensor device. By forming a coaxial pickup unit and a ring-shaped fetal heart rate electrode module at each monitoring point in the radiation zone, and further combining the pickup unit, the insulating isolation structure, the ring-shaped fetal heart rate electrode module, and the insulating isolation structure located between the pickup unit and the ring-shaped fetal heart rate electrode module to form a mechanical-electrical coupling / decoupling cooperative structure, the problem of "drift of effective pickup area caused by fetal position change" and "signal quality fluctuation caused by motion artifact" is solved at the structural level. It realizes robust acquisition and stable fit of fetal position change and motion artifact, thereby improving the reliability and availability of continuous monitoring and greatly improving the failure of monitoring equipment in continuous wearing scenarios.

[0091] To ensure accurate coaxial positioning and avoid inconsistencies in response caused by batch differences and assembly misalignment, one optional solution is that the semi-enclosed acoustic cavity base 206 in the acoustic sensing module 201 is further provided with a mounting reference surface, a central positioning boss, or a limiting step on its inner bottom surface for coordinated coaxial positioning; thereby ensuring accurate coaxial positioning; and simultaneously enabling sensing modules with different packaging forms to be installed at the same central position, maintaining consistent stable coupling area and preload with the acoustic cavity, and reducing inconsistencies in response caused by batch differences and assembly misalignment.

[0092] In an optional embodiment of the present invention, the pickup unit includes a piezoelectric ceramic sheet, a MEMS microphone array, a piezoresistive thin film, a piezoelectric thin film, or a MEMS vibration sensor.

[0093] In an optional embodiment of the present invention, the electrode material of the annular fetal heart electrode module 202 is a metallic material or a conductive elastomer material. Preferably, the electrode material is a conductive elastomer material, which can achieve the advantages of enhanced flexibility and contact stability.

[0094] In a further preferred embodiment of the present invention, optionally, the elastic vibration isolation structure 204 is a ring-shaped elastic vibration isolation structure 204; such as Figure 2 and Figure 3 The thickness of the pickup unit, the insulating isolation structure 203, the annular fetal heart electrode module 202, and the elastic vibration isolation structure 204 decreases radially in a stepped manner from the center outwards. In this solution, the structural combination with a stepped decrease in thickness is used to adjust the stress between the elastic vibration isolation structure 204 and the substrate of the radiation zone 2 from large to small, effectively absorbing shear and impact, reducing frictional noise and structural resonance caused by body motion, thereby improving the periodic consistency of the PCG waveform and the detectability of key features (such as S1 / S2).

[0095] In a preferred embodiment, the acoustic sensing module 201 further includes an acoustic matching layer or a damping layer. Specifically, the acoustic matching layer or damping layer can be, for example, an elastic damping material, a microporous structure, or a damping membrane. By adjusting the geometric parameters (cavity height, volume, opening area) of the adjustable acoustic cavity (cavity volume / opening / vent) and the damping-matching structure acoustic cavity, as well as the internal acoustic matching layer / damping layer, this solution can adjust the system's frequency response to the target fetal heart rate audio band and suppress sharp resonance peaks. Even when replacing sensors with different sensitivities or intrinsic frequency responses, the consistency of the overall frequency response can be achieved through cavity and damping matching, thereby improving the in-band flatness and SNR of the PCG signal.

[0096] In a further preferred embodiment, the flexible substrate is a star-shaped substrate, such as... Figure 1 As shown, the radiation area 2 is arranged in a star-shaped array around the central area 1, so that after fabrication, each of the fetal heart rate sensing sub-units 20 is arranged in a star-shaped array around the central control unit 10. Constructing a star-shaped array distribution on the substrate widens the effective signal window, eliminates point-based dependence, and significantly increases the probability (improved stability / continuity) that at any given time, at least one or more points are within the relatively effective window when fetal position / body position changes. This allows the central control unit 10 to select or fuse channels based on quality indicators, thereby addressing fetal position drift and changes in wearing status. This significantly improves the acquisition success rate. Compared to a scattered multi-point layout, the star-shaped layout has high spatial coverage, solving the problem that when fetal position shifts or the fetal back direction changes, a single point or a few points may deviate from the optimal pickup area, leading to a decrease or even interruption of the fetal heart rate signal amplitude.

[0097] The monitoring device provided by this invention, with a composite structure of "star-shaped multi-point array + coaxial acoustic electronic unit + vibration isolation / hardness gradient + insulation isolation" as its core, not only achieves robust acquisition and stable fit of tire position changes and motion artifacts, improving the failure of monitoring devices in continuous wearing scenarios, but also significantly improves the acquisition success rate, realizing true long-term, low-intervention monitoring.

[0098] In one optional implementation, to balance coverage redundancy and complexity, the number of fetal heart rate sensing sub-units 20 is 4 to 8. Increasing the number of fetal heart rate sensing sub-units 20 can improve spatial coverage probability and provide greater robustness to changes in fetal position; however, an excessive number will lead to increased wiring, assembly, cost, and power consumption. With the central area 1 as a reference, a number of less than 4 units results in insufficient directional coverage, easily leading to "quadrant blind spots," making it easier to miss the effective window when fetal position / back position changes, and increasing the probability of continuous monitoring interruption. When the number is greater than 8 units: the arm spacing is too small, the edges are crowded, inter-arm interference increases, the structure becomes complex, wiring density is high, thickness stacking increases the risk of edge warping, and wearability and reliability decrease. Therefore, a star array layout with 4 to 8 fetal heart rate sensing sub-units 20 balances directional coverage and uninterrupted long-term continuous monitoring signals, while avoiding the risks of inter-arm interference and edge warping, ensuring good wearability and high reliability. In a preferred embodiment, the number of fetal heart rate sensing subunits 20 is 5.

[0099] In a preferred embodiment, each radiation zone 2 contains one fetal heart rate sensing subunit 20. A total of 4-8 subunits are configured. In this embodiment, from the perspective of array observation, at least 4 points are needed to observe the spatial difference between maternal / fetal sources and noise, supporting "channel selection / fusion / blind source separation." If there are too few points, channel redundancy is insufficient, leading to a decrease in the significance of SQI drive selection, resulting in no backup channel when fetal position changes. From the perspective of wearability and power consumption, too many points increase power consumption and data bandwidth, and increase hardware failure rate. Too many points increase mutual interference (mechanical coupling, wiring crosstalk), increase thickness stacking, and increase algorithm and power consumption costs, without linearly improving performance. Numerous experimental studies have shown that setting one subunit per arm, for a total of 4-8 subunits, is the optimal balance point for "coverage, cost, and mass production."

[0100] Figure 6 A schematic diagram showing the distribution of connection points 30 at different stages of pregnancy in a fetal heart rate monitoring sensor device according to an embodiment of the present invention. (See attached diagram.) Figure 6In one optional embodiment, the arm-shaped connection area 3 is provided with multiple connection points 30 for fetal heart rate sensing sub-units 20; each fetal heart rate sensing sub-unit 20 is detachably connected to a corresponding connection point 30; each connection point 30 is adapted to the fetal heart rate position at different gestational weeks. This avoids signal acquisition failure caused by different gestational weeks and improves the monitoring accuracy at different gestational weeks.

[0101] In one optional embodiment of the present invention, the flexible substrate includes: a radiation region 2 connected to the central region 1 via at least seven arm-shaped connecting regions 3; each arm-shaped connecting region 3 connects to at least two radiation regions 2; and a fetal heart rate sensing subunit 20 is disposed on each of the radiation regions 2. The central control unit 10 is used to distinguish different fetal heart sounds based on the relative amplitude and temporal characteristics of the detection signals collected from each fetal heart rate sensing subunit 20, for multiple pregnancy monitoring; the detection signals include fetal electrocardiogram signals and fetal heart rate sounds. This broadens the applicability of the device.

[0102] Optionally, the fetal heart rate monitoring sensor further includes a skin interface layer. Specifically, the skin interface layer is an interface layer located between the flexible substrate and the skin. As a skin-friendly adhesive or gel layer, the skin interface layer fills the microscopic roughness of the skin, achieving stable adhesion pressure and reducing slippage. During assembly, the annular electrode and the acoustic module are coaxially arranged, ensuring that the acoustic pickup point and the electrode contact point are under consistent local coupling conditions, reducing acoustic channel response drift caused by changes in local adhesion, and further improving the stability of the PCG signal.

[0103] Optionally, the central control unit 10 integrates an analog front-end, an analog-to-digital converter, a microcontroller unit, and a wireless communication module, used to collect and process the fetal heart sounds and fetal electrical signals output by each of the sensing subunits to obtain the value of the uterine contraction index. For details of the process, please refer to the subsequent monitoring method section; this invention will not elaborate further here.

[0104] As a wearable medical device, this invention also provides detailed improvements in terms of flexibility and wearability.

[0105] To address the shortcomings of traditional solutions in terms of flexibility and wearability, and to avoid the problems associated with the traditional combination of "rigid modules + flexible straps," which struggles to fully conform to the curved surface of a pregnant woman's abdomen and can lead to discomfort after prolonged wear, a preferred embodiment uses a flexible star-shaped base. Specifically, in optional embodiments, the flexible star-shaped base is made of medical-grade flexible material, with zoned flexibility enhancements and replaceable hydrophilic gel patches, allowing pregnant women to wear it for extended periods in daily life. In addition, other specific implementations of flexible fit in this invention include: dispersing the fitting force through multiple arms to improve compliance, enabling the device to conform to the hyperboloidal surface of the pregnant woman's abdomen and reducing edge lifting. The "zoned stiffness / zoned thickness" design of the central area 1 and arm areas ensures that the central area 1 provides a more stable support for the control unit, while the arm areas are more flexible and bendable, achieving both "local stability and overall fit." The "local thickening or support island" in the arm end / sub-unit area forms a stable contact platform at the sensing sub-unit, preventing contact instability caused by excessive bending of the sub-unit with the arm area. Stepped / gradient hardness structure (gradual hardness change) forms a hardness gradient from the inside to the outside or from the center to the edge, reducing edge stress concentration and relative slippage, and improving long-term adhesion stability. Elastic vibration isolation / buffer layer (such as elastic rings, cushioning pads, microstructured elastic layers) absorbs normal pressure fluctuations and shear movements caused by breathing / body movement, reducing "adhesion pressure fluctuation → signal fluctuation". Skin interface layer: A composite structure of hydrophilic gel / conductive gel or skin-friendly adhesive layer provides microscopic adhesion (filling in skin micro-roughness), maintains moisture and adhesion, improves contact stability, and reduces contact impedance fluctuations. Edge anti-lifting structure: Thin edges / beveled / flexible edge rings reduce peeling torque by thinning or beveling the edges, preventing curling and lifting. Adjustable fixation structure: Abdominal band / adhesive patch / regional adhesion points provide uniform clamping force through adjustable constraints, adapting to different abdominal circumferences and gestational weeks, reducing local pressure marks and slippage. Multiple redundancy points: Even with imperfect local fit, effective contact points are still guaranteed. Even if the fit of one arm deteriorates in a certain area, the other arms can still maintain effective contact, improving usability. Flexible materials, partitioned thickness / rib / opening design, and replaceable hydrophilic gel / conductive interface ensure long-term comfortable fit on the abdominal curve, guaranteeing comfort and signal stability.

[0106] Optionally, the arm-shaped link area further includes: flexible wiring and stress relief structure for connecting each of the fetal heart rate sensing sub-units 20 to the central control unit 10; to avoid local warping or sub-unit displacement, sensor loosening, cavity leakage or changes in coupling conditions caused by long-term wear or pulling, ensuring long-term signal consistency and improving long-term wear reliability. In a typical example, the flexible wiring and stress relief structure can be serpentine lines or cushioning adhesive retention points.

[0107] Optionally, the fetal heart rate monitoring sensor also includes an encapsulation and sealing structure for sweat / water / loosening prevention. The encapsulation structure is used to seal the acoustic cavity opening, sensor leads, and wiring connections.

[0108] To monitor the fit of the fetal heart rate monitoring structure assembled above and avoid monitoring abnormalities caused by poor fit, in a further preferred embodiment of the present invention, a temperature sensing module and a pressure sensing module are provided around each fetal heart rate sensing subunit 20. The temperature sensing module is used to detect the local skin temperature; the pressure sensing module is used to detect the contact pressure of the fetal heart rate sensing subunit 20 on the skin. The central control unit 10 is used to periodically collect the local skin temperature and the contact pressure, and to evaluate the fit quality based on the local skin temperature, the contact pressure, the contact pressure fit threshold, and the temperature fluctuation threshold. When the collected contact pressure is lower than the contact pressure fit threshold and the temperature fluctuation is greater than the temperature fluctuation threshold, it is determined that the fit at the fetal heart rate sensing subunit 20 is poor; otherwise, it is determined that the fit meets the monitoring requirements. When the contact pressure is greater than the wearing pressure threshold and the local skin temperature continues to rise, the user can be prompted to loosen the restraint appropriately to avoid local pressure. The contact pressure adhesion threshold and local skin temperature fluctuation parameters are determined, and the optimal solution is confirmed based on the specific equipment and other conditions. This invention does not limit these aspects. Specifically, in one example, the temperature sensing module is an NTC thermistor or digital temperature chip embedded near each sub-unit.

[0109] Typical embodiments one through six are given below to further illustrate the significant progressive effects of the structure of the present invention:

[0110] To verify the robustness and signal quality of the basic structure of this invention in a real-world pregnant woman scenario, comparative experiments were conducted using the comparative structures of Comparative Examples 1-2 and Example 1:

[0111] Comparative Example 1 (Few-point separation type): Single-point or double-point arrangement is adopted, the acoustic sensor and electrode are set separately (non-coaxial, non-co-located), and there is no isolation structure between the independent acoustic cavity and the electrode support layer, nor is there an elastic vibration isolation / hardness gradient structure.

[0112] Comparative Example 2 (Multi-point but not co-located and coaxial): Multi-point arrangement is adopted, but the acoustic sensor and the electrode are only placed adjacent to each other, the center positions are inconsistent, and no ring coaxial electrode structure is set.

[0113] Example 1: A basic star-shaped five-point co-position acoustic-electric sensor is arranged in a star-shaped multi-arm multi-point array; each point is a co-position coaxial acoustic-electric integrated sub-unit (the acoustic module is located in the center and the ring electrode is coaxially surrounded); and an insulating isolation layer, an independent acoustic cavity and electrode support layer, an elastic vibration isolation / step hardness gradient structure and a skin-friendly interface layer are provided.

[0114] Example 1: Basic star-shaped five-point co-position acoustic-electric sensor (Comparative Examples 1 and 2 differ from the present invention only in whether they have the basic star-shaped five-point, coaxial co-position design of the present invention; other structural settings and dimensions are consistent or basically the same).

[0115] The structural parameters of Example 1 are set as follows: Number of arms: 5, angle between adjacent arms: 72°; Arm length: 100mm, center distance of sensing subunit from star center: 65mm; Piezoelectric ceramic sheet: diameter 12mm, thickness 0.3mm; Ring electrode: inner diameter 16mm, outer diameter 22mm, thickness 0.3mm; Substrate material: medical-grade liquid silicone, Shore A hardness 30HA. Material selection: The ring electrode substrate is 316L stainless steel with a 5μm thick Ag / AgCl electroplated layer; the hydrophilic gel pad is sodium polyacrylate-based hydrogel containing 0.9% physiological saline; the conductive adhesion layer is silver powder-filled polyurethane elastomer with a volume resistivity <5×10⁻⁶. -4 Ω·cm.

[0116] Performance tests will be conducted sequentially on the structures of Comparative Examples 1-2 and Example 1: Test scenarios and working conditions: Under the condition of wearing on the abdomen of pregnant women, signals will be collected under the working conditions of rest, deep breathing, slight body movement (turning over / sitting up / walking slowly); each working condition will be collected for no less than T minutes (e.g., 5–10 minutes), and the number of times the wearing position is adjusted, the number of signal interruptions, and the changes in quality indicators over time will be recorded. Evaluation indicators and judgment criteria: (1) Continuous availability (robustness): the proportion of effective signal per unit time AA (the proportion of time that meets the quality threshold), the number of disconnections, and the number of times repositioning / adjustment. (2) PCG quality indicators (PCG-SQI): energy ratio, period consistency, S1 / S2 detectability or template matching confidence in the target frequency band; and the mean and fluctuation (standard deviation) of the quality indicators will be statistically analyzed. (3) ECG quality indicators (ECG-SQI): R peak detection confidence / consistency, baseline drift index, mean and fluctuation of contact impedance (or characterized by impedance change rate). (4) Acousto-electric alignment stability: The stability of the time delay estimate between S1 / S2 and the R peak (variance / drift of the time delay), and the stability of the fused FHR / HRV output (such as variance within the short window or number of jumps). When the preset threshold is met (e.g., PCG-SQI>th threshold and ECG-SQI>th threshold), it is determined to be a "valid segment". The test scenarios and operating conditions and evaluation criteria of Examples 2-6 are similar to those of Example 1, and will not be repeated hereafter.

[0117] Test results of Example 1: In the test of 30 pregnant women with gestational weeks of 28–36, the time with at least one channel PCGSNR ≥12dB accounted for 96% of the total monitoring time; the success rate of detecting at least one channel ECGR peak was ≥98%; after multi-channel selective weighting, the mean absolute error of fetal heart rate relative to the reference CTG was less than 3 bpm.

[0118] Analysis of the results from Example 1 and Comparative Examples 1 and 2 shows that, compared to Comparative Examples 1 and 2, Example 1 exhibits a significantly higher effective signal ratio, fewer disconnections and repositioning times in scenarios related to body movement and fetal position changes. Furthermore, it shows smaller fluctuations in PCG and ECG quality indicators and lower acoustic-electrical alignment drift, thus achieving more stable FHR / HRV extraction and continuous monitoring. The basic structure of this invention demonstrates significantly higher robustness and signal quality than Comparative Examples 1 and 2 in real-world pregnant woman scenarios.

[0119] Example 2: Flexible reinforcement scheme based on conductive elastomer ring electrode (The difference between Example 2 and Example 1 lies in the type of electrode material in the ring fetal heart electrode module; Example 1 uses a metal electrode material, while Example 2 uses a conductive elastic electrode)

[0120] Based on Example 1, the annular electrode was replaced with a conductive elastomer: Electrode material: Silver powder filled silicone elastomer was used as the electrode body, with a silver powder mass fraction of 70%; the annular electrode with an inner diameter of 18 mm, an outer diameter of 24 mm, and a thickness of 0.8 mm was obtained by molding; a PEDOT:PSS conductive coating with a thickness of about 5 μm was sprayed on the surface.

[0121] Mechanical properties: The ring electrode has a Shore A hardness of 15–20 HA, which is significantly softer than the metal electrode in Example 1; the electrode resistance change rate is less than 10% under 20% stretching. Signal properties: After 30 minutes of wear, the median electrode contact impedance drift (1kHz) decreased from 20% of that of the metal electrode to about 8%; the subjective comfort score (out of 10) of pregnant women in late pregnancy (with greater abdominal curvature) increased by an average of 1.5 points.

[0122] This embodiment demonstrates the advantages of the present invention in achieving enhanced flexibility and contact stability through conductive elastomer materials.

[0123] Example 3: PCG module variant with MEMS microphone and miniature acoustic cavity (structural adjustment relative to Example 1: the design of the elastic vibration isolation structure 204 is optimized so that its damping frequency falls within the range of 3–10Hz).

[0124] In this embodiment, the acoustic sensing module is replaced by a MEMS microphone instead of a piezoelectric ceramic sheet: Acoustic module: A digital MEMS microphone with a noise floor of <30dBA and a package size of 3×4×1mm is selected; an acoustic cavity with a volume of approximately 0.5–1.0mL is constructed inside the sub-unit and coupled to the skin through a flexible waveguide; a soft film is covered at the entrance of the acoustic cavity to reduce surface shear noise. Structural adjustment: Due to the small mass of the MEMS module, the design of the elastic vibration isolation structure is optimized so that its damping frequency falls within the range of 3–10Hz; the ring electrode maintains the metal structure of Embodiment 1.

[0125] Test results: Under mild walking conditions, the low-frequency motion artifact amplitude in the PCG channel was reduced by about 35% compared to the piezoelectric pad solution; the time resolution for S1 / S2 was maintained within 10ms, meeting the requirements for fetal heart mechanical activity analysis.

[0126] This embodiment illustrates that the present invention is compatible with different types of acoustic sensors and ensures signal quality through structural design.

[0127] Example 4: Adjustable placement scheme to adapt to different gestational weeks (the difference from Example 1 is the addition of relevant structures to adapt to different gestational weeks)

[0128] To accommodate changes in fetal heart rate position at different gestational weeks, this embodiment features an adjustable installation position for the star-shaped base sensor subunit: Multiple installation positions are reserved on each arm, at distances of 50, 70, and 90 mm from the center, respectively. The sensor subunit can be reinstalled in any of these three positions via snap-fit ​​or magnetic connection. Usage: During the second trimester (20–28 weeks), the 50 mm position is preferred; during the third trimester (after 32 weeks), the 70 or 90 mm position can be selected to cover a larger area of ​​the abdomen. Users can adjust the position according to App prompts or doctor's guidance.

[0129] Test results: In a cohort of pregnant women aged 18–38 weeks, the success rate of first-time fetal heart rate signal localization increased from 80% to 94% after using an adjustable location scheme; the FHR signal interruption rate decreased by approximately 40% after adjusting the location.

[0130] This embodiment demonstrates the advantages of the present invention for multi-gestational week adaptation based on a star-shaped structure.

[0131] Example 5: Intelligent Adhesion Solution Integrating Temperature and Skin Pressure Sensing (The difference from Example 1 is the addition of temperature and pressure sensing structures)

[0132] In this embodiment, the sensor integrates temperature and skin pressure sensing structures around the sub-units for adhesion quality assessment: Temperature sensing is integrated into an NTC thermistor or digital temperature chip embedded near each sub-unit to detect local skin temperature. Temperature changes can be used to determine the degree of gel dryness and changes in local blood flow. Pressure sensing structure: Piezoresistive conductive filler is incorporated into the elastic vibration isolation structure, causing a measurable change in resistance when subjected to pressure. The central control unit periodically samples the pressure signal to estimate the contact pressure of the sub-unit on the skin. Adhesion quality evaluation: When the pressure signal of a sub-unit is significantly lower than the threshold and the temperature fluctuates greatly, the system determines that the adhesion at that point is poor and prompts the user to adjust the position; when the pressure is too high and the temperature continues to rise, the system can prompt the user to loosen the restraint appropriately to avoid local pressure. Related test data shows that this embodiment further improves the intelligence and safety of the sensor.

[0133] Example 6: Extended star-shaped structure suitable for twin / multiple pregnancy monitoring

[0134] For twin or multiple pregnancies, this embodiment expands the structure. Layout adjustment: The number of arms is increased to 7-8 on the star-shaped base, and twin sub-units are configured on some arms; through the array management strategy of the central control unit, a correspondence is established between signals from different regions and the cardiac cycles of different fetuses. Signal differentiation (depends on the backend algorithm, but the structure is a prerequisite). The PCG / ECG combined signals collected by each sub-unit have different spatial distributions, and different fetal heart sounds are distinguished by relative amplitude and temporal characteristics. The advantage of this structure is that it provides richer multi-point data for the algorithm.

[0135] Test results: In the simulated twin phantom experiment, using an extended star structure with 8 sub-units, the success rate of simultaneous recognition of twin heart rates reached 92%.

[0136] This embodiment demonstrates that the present invention can be adapted to complex multiple pregnancy monitoring scenarios through structural extensions.

[0137] The present invention provides the above-mentioned fetal heart rate monitoring sensing device. Combined with experiments, it shows that it systematically solves multiple problems at the structural level, such as the influence of fetal position changes and pressure changes on shear noise and contact impedance, and flexible wearing, and has significant improvement effect.

[0138] The present invention provides a method for manufacturing a fetal heart rate monitoring sensor device, which is used to prepare the monitoring sensor device described in any of the preceding claims. Figure 7 This is a schematic flowchart illustrating a method for manufacturing a fetal heart rate monitoring sensor according to an embodiment of the present invention. (See attached diagram.) Figure 7 The manufacturing method includes:

[0139] S11: Prepare a flexible substrate; each radiation region of the flexible substrate forms a semi-enclosed acoustic cavity base that carries the fetal heart sensing subunit, and an acoustic cavity is formed inside it;

[0140] S12: A pickup unit is formed at the center of the semi-enclosed acoustic cavity base;

[0141] S13: Using the central axis of the pickup unit as a reference and coaxial positioning technology, a ring-shaped fetal heart electrode module is formed on the semi-enclosed acoustic cavity base, and an insulation area is reserved between the pickup unit and the ring-shaped fetal heart electrode module.

[0142] S14: An insulating isolation structure is formed in the insulating area;

[0143] S5: An elastic vibration isolation structure is formed between the annular fetal heart electrode module and the semi-enclosed acoustic cavity base; the hardness of the elastic vibration isolation structure is less than that of the acoustic cavity base and the annular fetal heart electrode module;

[0144] S16: Connect each of the fetal heart rate sensing subunits to the conductive connection structure, install the conductive connection structure in the arm-shaped connection area of ​​the flexible substrate, and install the central control unit in the central area of ​​the flexible substrate.

[0145] The following section will elaborate on the manufacturing method of the fetal heart rate monitoring sensor:

[0146] S11: Prepare a flexible substrate; each radiation zone of the flexible substrate forms a semi-enclosed acoustic cavity base that carries the fetal heart sensing subunit, and an acoustic cavity is formed inside it.

[0147] The specific process for preparing the flexible substrate is as follows: a) Design a star-shaped mold to form a central area and several arm-shaped connecting areas; b) Inject liquid medical-grade silicone or TPU material into the mold, reserving mounting positions for the central control unit and the fetal heart rate sensor subunit on the substrate, and then heat-curing and shaping it. Local thickening and flexible rib design: The substrate area below the fetal heart rate sensor subunit is locally thickened to support the sensing structure; flexible ribs or openings are set in the radiation area to improve overall flexibility, allowing the flexible substrate to adapt to different abdominal curvatures.

[0148] Optionally, based on considerations of at least fit / comfort constraints, structural support constraints, and vibration isolation and signal stability, the thickness of the flexible substrate is 0.8–1.5 mm, with a central area extending outwards from 4–8 arm-like structures (preferably 5). Fit / comfort constraints: The hyperboloidal surface of the abdomen needs to be sufficiently flexible; an excessively thick substrate will significantly increase bending stiffness, leading to warping and slippage. Structural support constraints: The central area must bear the stress of the control unit and wiring; excessive thinness will cause collapse, local wrinkling, and unstable sub-unit pressure. Vibration isolation and signal stability: Appropriate thickness can provide shaping space for the vibration isolation structure and hardness gradient, suppressing PCG friction noise and ECG impedance fluctuations caused by bulk shear. Out-of-range effects: <0.8 mm: Substrate too soft → easy wrinkling / curling in the central and arm areas → unstable contact pressure, wiring pulling, sub-unit positioning drift → decreased signal SNR, increased artifacts. >1.5mm: Overly rigid substrate → decreased surface compliance → edge lifting / local pressure → discomfort during prolonged wear, gel delamination → reduced effective channels, decreased quality factor.

[0149] Optionally, the flexible base design fully considers the uncertainties in abdominal circumference and fetal heart position at different gestational weeks. The preferred layout of this invention is as follows: the central area uses the pregnant woman's navel as a positioning reference, and each arm naturally conforms to the abdominal curve. There are 5 arms (or 4, 6, or 8), with an angle of 60–90° between adjacent arms, preferably approximately 72°. The arm length is selected from 80–140 mm based on the typical pregnant woman's abdominal circumference. The fetal heart rate sensing subunit can be positioned 40–100 mm from the central area. Multiple mounting holes or mounting areas are pre-drilled on the arms to accommodate different gestational weeks; a two-level adjustable position design is preferred.

[0150] The design of the number of arms and the angle between adjacent arms in this invention is mainly constrained by the following factors: (1) Array coverage uniformity and redundancy: The more arms there are, the denser the spatial coverage, and the higher the probability that at least one point is in the effective pickup window when the tire position changes. (2) Adhesion and stress dispersion: The multi-arm structure can disperse the adhesion force to multiple directions, reducing the risk of edge lifting and slippage in a single direction; however, too many arms will cause crowding between arms, edge stacking, and an increase in local hard points, which is not conducive to curved surface adhesion. (3) Structural and electrical connection complexity: The more arms there are, the higher the wiring / packaging / assembly tolerance and power consumption cost, and the higher the reliability risk. (4) Wearable comfort: If the angle between adjacent arms is too small, it will cause squeezing between arms and edge stacking; if the angle is too large, there will be coverage blind spots or discontinuous adhesion. When the included angle is close to 60° (such as in a 6-arm configuration), the coverage is denser, but the arm spacing is reduced. If the material or package is too thick, it may lead to mutual interference between arms, edge stacking, and localized hard spots. When the included angle is close to 90° (such as in a 4-arm configuration), the structure is simpler, but the directional coverage is sparser, and the overall deviation from the effective area is more likely to occur when the arm position changes. Therefore, limiting the included angle to 60–90° can cover common configurations such as 4, 5, and 6 arms while taking into account the engineering feasibility of coverage and fit. This invention allows the included angle of adjacent arms to be adjusted within the range of 60–90° to obtain better fit and signal stability.

[0151] Similarly, under the above constraints, the 5-arm structure achieves a better balance between coverage uniformity, fit stability, and system complexity: the arms correspond to a uniform angular distribution of approximately 72°, providing near-isotropic spatial coverage, reducing "quadrant blind spots," and being insensitive to tire position deviation; compared to 4 arms (approximately 90°), 5 arms improve coverage redundancy and reduce the probability of signal interruption due to changes in tire back orientation; compared to 6–8 arms (approximately 60° or less), 5 arms significantly reduce wiring and packaging complexity, and avoid the risks of edge stacking, hard spots, and edge lifting caused by excessively small arm spacing, thus being more suitable for long-term wear on the curved surface of the abdomen. Therefore, when the number of arms is 5, the angle between adjacent arms is preferably approximately 72°; while also considering differences in abdominal circumference, material stiffness, and assembly methods.

[0152] The flexible substrate, sensing subunit, and central control unit of this invention can all be modularly designed, which facilitates fine-tuning of size and placement for different gestational weeks and different abdominal shapes. It can also be extended to heart sound / ECG and multi-site multimodal monitoring.

[0153] S12: A pickup unit is formed at the center of the semi-enclosed acoustic cavity base.

[0154] Optionally, the semi-enclosed acoustic cavity base is constructed from rigid or semi-rigid materials (such as PC, PBT, or highly filled silicone). The cavity may contain an acoustic matching layer and damping structure to adjust the frequency response to be relatively flat within the 20–200Hz range. The acoustic cavity material and the response within the "20–200Hz" band are crucial. Effective information about fetal heart sounds / abdominal heart sounds is primarily concentrated in the low frequencies; the goal of the cavity and damping design is to ensure a flat response in this frequency band and avoid sharp resonances that could lead to "excessive intensity / distortion at certain frequencies." Materials such as PC / PBT / highly filled silicone are chosen to balance: injection molding / encapsulation, adjustable acoustic damping, mechanical strength, and skin comfort. If the cavity resonance is too sharp or the frequency band deviates, it can cause waveform distortion, template matching difficulties, unstable S1 / S2 identification, and increased sensitivity to pressure changes.

[0155] Taking a piezoelectric ceramic sheet as the sound pickup unit as an example, the fabrication method of the acoustic sensing module is explained as follows: a) The piezoelectric ceramic sheet is punched or laser-cut to a specified size; b) An acoustic cavity is fabricated, with its internal volume and shape set according to acoustic simulation results; it also possesses excellent acoustic impedance matching performance; c) The piezoelectric sheet is fixed to the cavity using conductive adhesive or welding, and leads are connected. Damping / matching layers can be configured simultaneously.

[0156] Optionally, considering effective pickup area, resonance / bandwidth and damping, as well as structural thickness and comfort, the diameter of the piezoelectric ceramic sheet mounted on the semi-enclosed acoustic cavity base is set to 10–15 mm, and the thickness to 0.2–0.5 mm. The electrodes on its back are made of copper or brass. Effective pickup area: Increased diameter → increased coupling area → stronger low-frequency heart sound energy pickup (fetal heart sounds are mainly in the low frequency range, with actual energy concentrated in the tens to hundreds of Hz range). Resonance / bandwidth and damping: Thickness affects the stiffness and resonance characteristics of the piezoelectric sheet; with wearable packaging and a damping layer, this range makes it easier to achieve a usable response within the target frequency band. Structural thickness and comfort: Excessive thickness significantly increases local protrusions, affecting fit and introducing shear noise. If the diameter is <10 mm: insufficient pickup area → decreased SNR → fetal heart sounds are more easily drowned out by maternal / environmental noise. If the diameter is >15 mm: increased local stiffness and space occupation → poor fit, edge lifting, and increased motion artifacts. Thickness <0.2mm: prone to cracking / reduced assembly yield and poor output consistency. Thickness >0.5mm: excessive stiffness, obvious local hard spots → reduced comfort and increased shear noise.

[0157] Optionally, the piezoelectric ceramic sheet is connected to the signal output terminal of the sub-unit via leads. Besides using piezoelectric ceramic sheets for sound pickup, the pickup component can also be a MEMS microphone, a piezoresistive film, a piezoelectric film, a MEMS vibration sensor, etc.

[0158] S13: Using the central axis of the pickup unit as a reference and coaxial positioning technology, a ring-shaped fetal heart electrode module is formed on the semi-enclosed acoustic cavity base, and an insulation area is reserved between the pickup unit and the ring-shaped fetal heart electrode module.

[0159] Fabrication of the annular fetal heart electrode module: a) Prepare an annular metal substrate and perform stamping and polishing; b) Form an Ag / AgCl coating by electroplating or spray conductive polymer / conductive silver paste on its surface; c) Fix the annular electrode on the outer ring of the insulating isolation structure and connect it with the flexible wiring.

[0160] Optionally, considering the influence of coaxial colocation constraints, contact impedance, and stability, the annular electrode of the annular tire heart electrode module arranged around the piezoelectric ceramic sheet is set with an inner diameter of 14–20 mm, an outer diameter of 18–26 mm, and a width of 2–5 mm. Coaxial colocation constraints: The electrode must form a ring around the acoustic module; the inner diameter needs to accommodate the acoustic module and the insulation isolation area; the outer diameter is limited by the sub-unit's footprint and fit comfort. Contact impedance and stability: If the effective electrode area is too small, the contact impedance increases and fluctuates greatly; if it is too large, the edges are more prone to curling / lifting and are more susceptible to shear effects. A width of 2–5 mm is to ensure sufficient area while avoiding an excessively wide ring that leads to "hard edges / stress concentration." If the width is <2 mm: insufficient area → high impedance and high noise. If the width is >5 mm or the outer diameter is too large: fitting is difficult, edge artifacts and friction noise increase; the larger footprint affects the density of multi-point layout. If the inner diameter is too small, the coaxial structure is difficult to assemble and the insulation area is insufficient; if the inner diameter is too large, the electrode is too far from the acoustic center, which weakens the "co-location" advantage and reduces the consistency of acoustic-electric coupling.

[0161] For both electrical and mechanical isolation considerations, the thickness of the annular electrode is set to 0.2–0.8 mm. Electrical isolation: Sufficient thickness is required to prevent leakage or electrochemical interference between the electrode and the acoustic module / leads. Mechanical isolation: This is also part of the "decoupling of the acoustic cavity from the electrode support layer." Too thin a thickness results in insufficient isolation, while too thick a thickness increases the stacking height, leading to poor fit. If the thickness is <0.2 mm: insufficient isolation, increased assembly tolerance risks, and potential short circuit / interference risks. If it is >0.8 mm: excessive sub-unit thickness → localized hard spots → poor surface fit, and increased shear noise.

[0162] Optionally, the material of the ring electrode can be stainless steel or titanium alloy substrate, with an Ag / AgCl coating formed on its surface by electroplating or spraying. Alternatively, it can be conductive silicone filled with silver powder or a PEDOT:PSS composite conductive coating.

[0163] Optionally, an insulating structure may be provided between the ring electrode and the piezoelectric ceramic sheet. The insulating structure may be made of medical-grade silicone or epoxy resin.

[0164] S14: An insulating isolation structure is formed in the insulating area to prevent the electrical path from being affected by the acoustic structure.

[0165] S15: An elastic vibration isolation structure is formed between the annular fetal heart electrode module and the semi-enclosed acoustic cavity base; the hardness of the elastic vibration isolation structure is less than that of the acoustic cavity base and the annular fetal heart electrode module. The hardness of the elastic vibration isolation structure is less than that of the semi-enclosed acoustic base; it is used to absorb shear stress.

[0166] Optionally, the elastic vibration isolation structure is an elastic ring.

[0167] Optionally, the material of the elastic vibration isolation structure is an elastic vibration isolation material, specifically silicone or polyurethane material with a Shore A hardness of 10–25HA, and a stepped thickness gradient structure is provided in the radial direction to achieve a gradual change in hardness from the acoustic module to the flexible substrate.

[0168] Alternatively, the elastic vibration isolation structure can be formed by injecting elastic vibration isolation material into the periphery of the acoustic module and the annular fetal heart electrode module; thereby achieving a stepped hardness gradient to reduce local stress concentration.

[0169] S16: Connect each of the fetal heart rate sensing subunits to the conductive connection structure, and install the conductive connection structure in the arm-shaped connection area of ​​the flexible substrate, and install the central control unit in the central area of ​​the flexible substrate. The signal lead is connected to the central control unit through a flexible trace, and the connection point adopts a chamfer and stress relief structure to avoid breakage caused by repeated bending.

[0170] The manufacturing method also includes forming a top protective cover. Optionally, the top protective cover can be manufactured using a two-color injection molding process.

[0171] The manufacturing process also includes encapsulation and connection: including: Central control unit and overall assembly: a) Soldering components such as AFE / ADC, MCU, temperature, and wireless communication modules to the control PCB; b) Fixing the PCB to the central area and connecting it to the flexible traces of each arm via connectors or direct soldering; c) Integrating the central control unit and flexible substrate into a single encapsulation using whole-machine molding or encapsulation processes. Skin interface layer and encapsulation: Assembly of gel / conductive interface layers (replaceable / replenishable / microporous, etc.) + overall encapsulation and sealing. Flexible traces and stress relief connection: Connection of FPC / wires to sub-units and the central control unit, with stress relief achieved through serpentine lines / buffered adhesive. The entire sub-unit is encapsulated by the upper shell and fixedly connected to the flexible traces. Flexible traces and stress relief structure: Arranged along the inside or surface of the arm for transmitting signals and power, and designed with S-shaped bends or serpentine coils near the sub-units to absorb tensile stress.

[0172] After fabrication, calibration and testing are performed, including: a) acoustic response and electrode impedance testing for each subunit; b) bending, torsion and tensile fatigue testing for the entire unit; and c) testing PCG / ECG signal quality and multi-point array performance on a standard phantom / simulation platform.

[0173] The structure fabricated by the aforementioned device manufacturing method of this invention provides structural prerequisites for multimodal algorithms: through multi-point distribution and co-location acquisition—based on coaxial design and stepped vibration isolation design—it facilitates subsequent array selection, multi-channel blind source separation, and quality factor-driven channel weighting. Based on the aforementioned fetal heart rate monitoring structural design, this invention also provides a fetal heart rate monitoring method, applicable to the fetal heart rate monitoring sensing device as described in any of the preceding claims, achieving "fit-quality assessment-driven channel selection / fusion and acoustic-electric alignment" at the method level.

[0174] Figure 8 A schematic flowchart of a fetal heart rate monitoring method according to an embodiment of the present invention is shown. (See attached diagram.) Figure 8 The monitoring method includes:

[0175] S20: The acoustic sensing module and the annular fetal heart electrode module of each of the fetal heart sensing subunits respectively collect the fetal heart sound signal and the fetal heart electrical signal.

[0176] S21: The central control unit acquires the corresponding fetal heart sound signal and fetal heart electrical signal in each radiation zone.

[0177] S22: The value of the uterine contraction index is calculated using the fetal heart sound signals and fetal electrical signals of each group.

[0178] Optionally, in step S22: using the fetal heart rate signals and fetal electrocardiogram signals from each group, the value of the uterine contraction index is calculated, specifically including steps S221~S223:

[0179] Step S221: Calculate the signal quality index of each group of fetal heart sound signals and fetal electrocardiogram signals, and perform channel selection or weighted fusion to obtain robust fetal heart sound signals and robust fetal electrocardiogram signals. Specifically: Quality evaluation of fetal heart sensing sub-units: Calculate the signal quality index (SQI) (such as SNR (Signal to Noise Ratio), period consistency, bandwidth-to-energy ratio, contact impedance stability, etc.) for each sub-unit; Channel selection or weighted fusion: Select one or more channels with the highest SQI; or fuse multiple channels according to the weight w(Q, SQI) to obtain robust PCG / ECG.

[0180] Step S222: Time alignment is performed on each group of robust fetal heart sound signals and robust fetal electrocardiogram signals to obtain the preprocessed fetal heart sound signals and fetal electrocardiogram signals of each group; specifically, time alignment is performed by utilizing the synchronization advantage brought by co-location and coaxiality; and artifact removal or adaptive filtering is performed according to motion / pressure changes to achieve acoustic-electric alignment and artifact suppression.

[0181] Step S223: Calculate the values ​​of the uterine contraction indicators using the preprocessed fetal heart rate signals and fetal electrical heart rate signals from each group. Specifically, this includes: outputting fetal heart rate (FHR), HRV (or other), and (optionally) outputting uterine contraction-related indicators or alarms.

[0182] The monitoring device provided by this invention inherently adapts to multimodal algorithms: star-shaped multi-point co-location acquisition offers advantages for backend blind source separation, template cancellation, and quality factor-driven channel weighting, enhancing the overall system performance from a structural perspective. Firstly, the significance of star-shaped multi-point acquisition is that it is not simply "adding one more point." During signal acquisition, it is necessary to separate the "fetal source" from the "maternal source + noise." Template cancellation is easier to perform (especially for maternal components). Many interferences exhibit stronger "coherence" or "predictability" across different points, such as: maternal ECG (more stable in frequency band and morphology, and usually with stronger amplitude); slowly varying components in electrode contact artifacts; certain modes of environmental power frequency / mechanical vibration; when there are multiple channels, a maternal component template (or a heartbeat template based on R-peak alignment) can be established on a "high-quality channel" and then projected / cancelled onto other channels: the better the synchronicity and the more channels, the more stable the template estimation; during cancellation, spatial correlation and weight differences can be utilized to reduce false positives on the target source (fetal signal); the significance of star-shaped multi-point is that it is not simply "adding one more point," but rather forming spatial coverage, thus making template cancellation controllable in "who is the template, where to cancel, and how much to cancel." II. "Co-location acquisition" offers advantages. "Co-location acquisition" amplifies the benefits for these algorithms: making fusion / alignment more reliable. A more crucial point of this scheme is that each point is still "PCG / ECG co-located and coaxial." This brings two direct benefits: synchronous observation under the same local tissue coupling conditions: making cross-modal fusion (acoustic + electrical) more consistent. Reducing spatial path difference and drift: making template construction, alignment, and cancellation more stable (especially under dynamic wear). A typical example is a fetal heart rate monitoring method, which specifically includes: 1. Aligning the central area with the pregnant woman's navel, allowing each sensing sub-unit to naturally conform to the abdominal curve. 2. Wearing and position initialization: attaching the star-shaped array to the target area of ​​the abdomen; (optionally) guiding the user to adjust the position / angle as prompted. 3. Fit quality assessment: calculating the fit quality index Q (e.g., contact stability, slippage, pressure range) based on at least one of pressure / impedance / temperature / IMU. 4. Synchronous acquisition: synchronously acquiring PCG and ECG (co-located and coaxial) from multiple sub-units. 5. Sub-unit quality evaluation: calculating the signal quality index SQI (e.g., SNR, period consistency, bandwidth-to-energy ratio, contact impedance stability, etc.) for each sub-unit. 6. Channel Selection or Weighted Fusion: Select one or more channels with the highest SQI; or fuse multiple channels according to the weight w(Q, SQI) to obtain robust PCG / ECG. 7. Acoustic-Electro-Audio Alignment and Artifact Suppression: Utilize the synchronization advantage of coaxial alignment for timing alignment; and perform artifact removal or adaptive filtering based on motion / pressure changes. 8. Index Output: Output fetal heart rate FHR, HRV (or other), and (optionally) output uterine contraction-related indicators or alarms.

[0183] In summary, this invention addresses the structural failure of a few-point layout schemes caused by fetal position changes and motion artifacts in continuous wear scenarios. It significantly improves the signal amplitude fluctuations and signal interruption issues that occur when the fetal position shifts, the fetal back turns, or the pregnant woman's position changes. The coaxial design of the fetal heart sound and electrocardiogram sensing modules solves the problem of complex timing alignment and fusion processing caused by the different acoustic propagation paths and electrical conduction paths of the heart sounds and electrocardiograms, coupled with changes in skin contact state, leading to decreased algorithm robustness. This reduces spatial path differences and dynamic drift of the signal at the source. Furthermore, the partitioned hardness step-like structural design ensures stable acoustic coupling for the acoustic sensing module without introducing strong shear noise due to excessive local pressure. This suppresses the influence of pressure changes / shear motion on acoustic shear noise and skin contact impedance fluctuations (suppression here includes resistance to motion artifacts and impedance drift), achieving synergistic optimization of mechanical and electrical coupling. Simultaneously, the ring electrode achieves uniform pressure distribution, reducing contact impedance fluctuations.

[0184] Furthermore, the sensor array is designed in a star-shaped distribution, which offers higher spatial coverage compared to a scattered multi-point layout. This widens the effective signal window and significantly increases the probability that at least one or more points are within the relatively effective window at any given time, even with changes in fetal / body position (improved stability / continuity). This allows the central control unit to select or fuse channels based on quality indicators, thus addressing changes in fetal position drift and wearing status. This significantly improves the data acquisition success rate.

[0185] Furthermore, based on the aforementioned fetal heart rate monitoring structure design, this invention achieves "channel selection / fusion and acoustic-electric alignment driven by fit quality assessment" at the methodological level.

[0186] In summary, this invention provides an effective solution to the failure problem of monitoring devices under continuous wear in fetal monitoring scenarios, and has significant effects and application prospects.

Claims

1. A fetal heart rate monitoring sensor, characterized in that, include: A flexible substrate includes: a central region, an arm-shaped connecting region, and a plurality of radiating regions connected to the central region through the arm-shaped connecting region; The central control unit is located in the central area; A conductive connection structure disposed in the arm-shaped connection region; A plurality of fetal heart rate sensing subunits are respectively disposed on each of the radiation zones; each of the fetal heart rate sensing subunits is electrically connected to the central control unit through the conductive connection structure; each of the fetal heart rate sensing subunits includes: An acoustic sensing module includes a semi-enclosed acoustic cavity base and a pickup unit; the pickup unit is placed on the bottom surface inside the semi-enclosed acoustic cavity base; the acoustic sensing module is used to collect fetal heart sound signals. A ring-shaped fetal heart rate electrode module is used to acquire fetal heart rate electrical signals; the ring-shaped fetal heart rate electrode module is arranged coaxially around the central axis of the pickup unit so that the fetal heart rate sensing subunit performs co-position acquisition of the fetal heart rate sound signal and the fetal heart rate electrical signal. An insulating and isolating structure is located between the pickup unit and the annular fetal heart electrode module; An elastic vibration isolation structure is disposed between the annular fetal heart electrode and the side wall of the semi-enclosed acoustic cavity base, and its hardness is lower than that of the acoustic cavity base and the annular fetal heart electrode module. The central control unit is used to acquire the corresponding fetal heart sound signals and fetal electrical signals in each radiation zone; and to calculate the value of the uterine contraction index using each set of fetal heart sound signals and fetal electrical signals.

2. The fetal heart rate monitoring sensor device as described in claim 1, characterized in that, The elastic vibration isolation structure is a ring-shaped elastic vibration isolation structure; The thickness of the pickup unit, the insulating isolation structure, the annular fetal heart electrode module, and the elastic vibration isolation structure decreases radially in a stepped manner from the center outwards.

3. The fetal heart rate monitoring sensor device as described in claim 2, characterized in that, The flexible substrate is a star-shaped flexible substrate, and the radiation areas are arranged in a star-shaped array around the central area, so that after fabrication, each of the fetal heart sensing sub-units is arranged in a star-shaped array around the central control unit.

4. The fetal heart rate monitoring sensor device as described in claim 3, characterized in that, The number of fetal heart rate sensing subunits is 4 to 8.

5. The fetal heart rate monitoring sensor as described in claim 4, characterized in that, The arm-shaped connection area is provided with multiple connection points for fetal heart rate sensing subunits; the fetal heart rate sensing subunits are detachably connected to the corresponding connection points; each connection point is adapted to the fetal heart rate position at different gestational weeks.

6. The fetal heart rate monitoring sensor as described in claim 5, characterized in that, The flexible substrate includes: a radiating region connected to the central region via at least seven arm-shaped connecting regions; each arm-shaped connecting region connects to at least two of the radiating regions; and the fetal heart rate sensing subunit is disposed on each of the radiating regions. The central control unit is used to distinguish different fetal heart sounds based on the relative amplitude and temporal characteristics of the detection signals from each fetal heart sensing subunit, so as to perform multiple pregnancy monitoring; the detection signals include fetal electrical signals and fetal heart sound signals.

7. The fetal heart rate monitoring sensor device as described in claim 6, characterized in that, Also includes: Temperature sensing modules and pressure sensing modules are set around each fetal heart rate sensing subunit; The temperature sensing module is used to detect local skin temperature; The pressure sensing module is used to detect the contact pressure of the fetal heart rate sensing subunit on the skin. The central control unit is used to periodically collect the local skin temperature and the contact pressure, and to evaluate the adhesion quality based on the local skin temperature and the contact pressure, as well as the contact pressure adhesion threshold and the temperature fluctuation threshold. When the contact pressure is lower than the contact pressure adhesion threshold and the temperature fluctuation is greater than the temperature fluctuation threshold, it is determined that the adhesion at the fetal heart rate sensing subunit is poor. Otherwise, the fit is deemed to meet the monitoring requirements.

8. A method for manufacturing a fetal heart rate monitoring sensor, characterized in that, The method for manufacturing the monitoring and sensing device as described in any one of claims 1-7 comprises: A flexible substrate is prepared; each radiation region of the flexible substrate forms a semi-enclosed acoustic cavity base that carries the fetal heart rate sensing subunit, and an acoustic cavity is formed inside it; A pickup unit is formed at the center of the semi-enclosed acoustic cavity base; Using the central axis of the pickup unit as a reference and employing coaxial positioning technology, a ring-shaped fetal heart electrode module is formed on the semi-enclosed acoustic cavity base, and an insulation area is reserved between the pickup unit and the ring-shaped fetal heart electrode module. An insulating isolation structure is formed in the insulating region; An elastic vibration isolation structure is formed between the annular fetal heart electrode module and the semi-enclosed acoustic cavity base; the stiffness of the elastic vibration isolation structure is less than that of the acoustic cavity base and the annular fetal heart electrode module. Each of the fetal heart rate sensing subunits is connected to a conductive connection structure, and the conductive connection structure is installed in the arm-shaped connection area of ​​the flexible substrate, and the central control unit is installed in the central area of ​​the flexible substrate.

9. A method for fetal heart rate monitoring, characterized in that, The fetal heart rate monitoring sensor, as described in any one of claims 1-7, comprises the following monitoring method: The acoustic sensing module and the annular fetal heart electrode module of each of the fetal heart sensing subunits respectively collect the fetal heart sound signal and the fetal heart electrical signal; The central control unit acquires the corresponding fetal heart sound signals and fetal electrical signals in each radiation zone; The values ​​of uterine contraction indices were calculated using the fetal heart sound signals and fetal electrical signals of each group.

10. The fetal heart rate monitoring method as described in claim 9, characterized in that, The steps for calculating the values ​​of uterine contraction indices using various sets of fetal heart sound signals and fetal electrocardiogram signals specifically include: Calculate the signal quality index of each group of fetal heart sound signals and fetal electrocardiogram signals, and perform channel selection or weighted fusion to obtain each group of robust fetal heart sound signals and robust fetal electrocardiogram signals; Time-series alignment was performed on the robust fetal heart rate signals and robust fetal electrocardiogram signals of each group to obtain the preprocessed fetal heart rate signals and fetal electrocardiogram signals of each group. The values ​​of the uterine contraction index are calculated using the preprocessed fetal heart rate signals and fetal electrocardiogram signals from each group.

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