Row-column addressing area array flexible ultrasonic transducer integrated with electrocardiogram monitoring and preparation method of row-column addressing area array flexible ultrasonic transducer

Abstract

The invention discloses a row-column addressing area array flexible ultrasonic transducer integrated with electrocardiogram monitoring and a preparation method thereof.An ultrasonic function unit takes a flexible circuit board as a core carrier, integrates independent piezoelectric array elements, a top flexible electrode layer and a flexible acoustic matching layer which are distributed in rows and columns, and is controlled through a row-column addressing electrode array; and the number of the leads is reduced from N2 to 2N. The electrocardio monitoring unit comprises electrocardio sensing electrodes which are integrated together. The package structure covers the non-functional surface to provide protection. The ultrasonic array and the electrocardio sensing electrode are conformally integrated on the same flexible substrate, so that synchronous and homologous monitoring of mechanical movement and electrophysiological activity of the heart is realized. Due to the flexible design, the transducer can be adaptive to the curved surface of the chest of a human body and tolerate deformation caused by cardiac pulsation and respiration, and the accuracy, stability and comfort in wearable long-term dynamic heart monitoring are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of flexible electronics and MEMS ultrasonic transducer technology, specifically relating to a row and column addressable array flexible ultrasonic transducer for integrated electrocardiogram monitoring and its fabrication method. Background Technology

[0002] Ultrasound technology, due to its radiation-free operation, real-time imaging, and deep tissue detection capabilities, has become an important tool for assessing cardiac structure and function. To achieve clear capture of dynamic cardiac motion, valvular activity, and blood flow information, the ultrasound transducer used must have both high spatial and temporal resolution, which places extremely high demands on the array element density, fit, and flexibility of the probe.

[0003] Traditional ultrasonic transducers typically use rigid bulk materials such as piezoelectric ceramics (PZT) as their core, which leads to problems such as large size, acoustic impedance mismatch with human soft tissue, and difficulty in adapting to the curved shape of the chest. This can easily cause air gaps to form between the probe and the skin, thereby weakening the effective transmission of ultrasound signals and affecting image quality.

[0004] Microfabrication-based ultrasonic transducers, especially piezoelectric microfabricated ultrasonic transducers (PMUTs), have made high-density array integration possible. However, existing PMUTs are mostly built on rigid substrates such as silicon and glass, which lack flexibility and cannot maintain a stable and conformal fit with the human chest during heartbeats and respiratory movements, thus limiting their application in long-term, dynamic cardiac monitoring.

[0005] To further improve imaging quality, two-dimensional area array probes with electronic scanning and three-dimensional beam focusing capabilities have become the development direction. However, in traditional fully-access (FA) two-dimensional arrays, the number of array elements increases quadratically with the scale, leading to a sharp increase in the number of leads. This brings challenges such as complex manufacturing processes, difficult interconnection, and high costs, making them unsuitable for portable or wearable devices. To reduce lead complexity, row-column addressing (RCA) solutions have emerged. This structure interconnects row and column electrodes, requiring only 2N leads to control an N×N array, significantly simplifying the system. Nevertheless, existing row-column addressing ultrasonic transducers still mostly use rigid or semi-rigid substrates, and the problem of insufficient fit has not been fundamentally solved. In dynamic monitoring, poor coupling can easily lead to signal quality degradation.

[0006] Furthermore, a complete assessment of cardiac function typically requires combining structural / blood flow information (provided by ultrasound) and electrical activity information (provided by electrocardiography). The standard clinical practice is to perform echocardiography and electrocardiography separately. This separation of equipment leads to asynchronous data, making it difficult to accurately analyze the instantaneous correlation between electrical activity and mechanical contraction. For example, in assessing the impact of arrhythmias on cardiac function, while existing technologies have attempted to mechanically combine independent ECG electrode patches with ultrasound probes, these methods generally suffer from problems such as relative displacement between the electrodes and probe leading to signal asynchrony, and poor adhesion between rigid electrodes and skin, which can introduce motion artifacts.

[0007] In summary, there is a lack of existing technologies that can simultaneously satisfy both excellent flexible conformal fitting and synchronous physiological signal acquisition. Summary of the Invention

[0008] To address the problems existing in the prior art, the present invention aims to provide a row-column addressable array flexible ultrasound transducer for integrated electrocardiogram monitoring and its preparation method. The row-column addressable array flexible ultrasound transducer of the present invention has excellent flexibility, achieves conformal fitting, and can synchronously acquire physiological signals.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A row-column addressable flexible ultrasound transducer for integrated electrocardiogram (ECG) monitoring includes a signal detection unit encapsulated in a flexible packaging material. The signal detection unit comprises a flexible circuit board and an ultrasound functional unit and an ECG monitoring unit disposed on the flexible circuit board. The flexible circuit board has a row-oriented metal electrode array. The ultrasound functional unit includes a piezoelectric material layer, a top flexible electrode layer, a flexible acoustic backing layer, and a flexible acoustic matching layer. The piezoelectric material layer is electrically connected to the row-oriented metal electrode array. The flexible acoustic backing layer is disposed on the flexible circuit board on the side opposite to the piezoelectric material layer. The top flexible electrode layer... On the side of the piezoelectric material layer opposite to the row-oriented metal electrode array and electrically connected to the piezoelectric material layer, a flexible acoustic matching layer is disposed on the top flexible electrode layer. On the side opposite to the piezoelectric material layer, the row-oriented metal electrode array includes multiple independent row electrodes, the top flexible electrode layer includes multiple independent column electrodes, and the piezoelectric material layer includes multiple independent piezoelectric array elements distributed in multiple rows and columns. Piezoelectric array elements located in the same row are electrically connected to a row of electrodes, and piezoelectric array elements located in the same column are electrically connected to a column of electrodes. The ECG monitoring unit includes ECG sensing electrodes for detecting ECG sensing signals.

[0010] Preferably, the electrocardiogram sensing electrode is disposed on the flexible circuit board and located on the outer periphery of the piezoelectric material layer; Alternatively, the electrocardiogram sensing electrode is disposed on a flexible acoustic matching layer, and an electromagnetic shielding film is disposed between the electrocardiogram sensing electrode and the flexible acoustic matching layer.

[0011] Preferably, the flexible encapsulation material has an exposure window on the functional surface of the ECG sensing electrode, and the gaps in the row-oriented metal electrode array, the piezoelectric material layer, and the top flexible electrode layer are all filled with the flexible encapsulation material.

[0012] Preferably, the functional surfaces of the electrocardiogram sensing electrodes are provided with a conductive hydrogel layer.

[0013] Preferably, the row-oriented metal electrode array and the top flexible electrode layer are led out through a first external interface on the flexible circuit board; the electrocardiogram (ECG) sensing electrode is electrically connected to the ECG signal lead, which is electrically isolated from the row-oriented metal electrode array and the top flexible electrode layer on the flexible circuit board 1, and the ECG signal lead is led out through a second external interface on the flexible circuit board.

[0014] Preferably, the first external interface and the second external interface are both independent gold finger structures and are integrated in different areas of the flexible circuit board.

[0015] Preferably, the surfaces of the flexible circuit board where the flexible acoustic backing layer is disposed and the surfaces where the piezoelectric material layer is disposed are covered with an electromagnetic shielding film, except for the row-oriented metal electrode array, the top flexible electrode layer, the electrocardiogram sensing electrode area, the second external interface, and the exposed conductive area of ​​the second external interface.

[0016] Preferably, a plurality of electrocardiogram (ECG) sensing electrodes are provided, which surround the piezoelectric material layer and are arranged at the corners or edges of the extended area around the flexible circuit board, away from the acoustic radiation area of ​​the ultrasound functional unit.

[0017] Preferably, the flexible acoustic backing layer is made of a high-damping flexible material, which is epoxy resin filled with tungsten powder or alumina powder, or silicone rubber filled with tungsten powder or alumina powder. The flexible acoustic matching layer is made of a flexible polymer film with a specific acoustic impedance, wherein the flexible polymer film is a polyurethane film. The piezoelectric array element material is any one of piezoelectric ceramics, piezoelectric single crystals, piezoelectric polymers, or piezoelectric composite materials, and the size of the piezoelectric array element along both the row and column directions is no greater than or less than 1 mm. The piezoelectric array element is fixedly connected to the row electrode of the row-direction metal electrode array through a conductive silver paste adhesive layer; The flexible encapsulation material is polydimethylsiloxane.

[0018] Preferably, the material of the top flexible electrode layer is a conductive fabric or a conductive tape; wherein, the conductive fabric includes a silver-coated nylon fiber or a copper-nickel alloy wire hybrid structure, and the conductive tape includes a carbon-based conductive layer and a pressure-sensitive adhesive composite structure or a silver nanowire transparent conductive film.

[0019] The present invention also provides a method for fabricating a row-column addressable array flexible ultrasound transducer for integrated electrocardiogram monitoring as described above, comprising the following steps: S1. Substrate pretreatment: Isopropanol is used to ultrasonically clean the surface of the row-direction metal electrode array of the flexible circuit board, the piezoelectric material connection surface for preparing the piezoelectric material layer, and the electrocardiogram sensing electrode connection surface. S2. Piezoelectric layer bonding and row array element forming: A conductive adhesive is coated on the surface of the metal electrode array in the row direction on the front side of the flexible circuit board 1. A piezoelectric material for preparing the piezoelectric material layer is attached to the surface of the conductive adhesive. After the conductive adhesive is cured, the piezoelectric material layer is divided into multiple independent piezoelectric array elements distributed in multiple rows and columns. S3. Row electrode isolation: The row-oriented metal electrode array on the flexible circuit board is cut along the row gap in the piezoelectric material layer to form multiple electrically isolated and independent row electrodes; S4. Top flexible electrode layer integration and column electrode forming: The top flexible electrode layer material is connected to the surface of the piezoelectric material layer, and then the top flexible electrode layer material is divided along the column gap in the piezoelectric material layer to obtain multiple independent column electrodes, forming the top flexible electrode layer, and the column electrodes are electrically connected to the column direction metal electrode array on the flexible circuit board. S5. Gap filling: Flexible encapsulation material is used to fill the gaps in the row-oriented metal electrode array, the piezoelectric material layer, and the top flexible electrode layer; S6. Forming of flexible acoustic backing layer: Coating or pressing acoustic backing material onto the surface of the flexible circuit board opposite to the piezoelectric material layer and curing it to form a flexible acoustic backing layer; S7. Attachment of flexible acoustic matching layer 6: Attach a flexible acoustic matching layer to the surface of the top flexible electrode layer; S8. Electrode bonding: A conductive adhesive is applied to the pads on the outer periphery of the piezoelectric material layer on the flexible circuit board for mounting the electrocardiogram sensing electrodes, and then the electrocardiogram sensing electrodes are bonded together and the conductive adhesive is cured. S9. Encapsulation Structure Forming: Liquid flexible encapsulation material is used to cover the non-functional surface of the entire signal detection unit through dispensing, molding or vacuum potting processes, and the functional areas of the ECG sensing electrodes are windowed or covered with conductive hydrogel, and then cured to form an encapsulation structure.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The row-column addressable flexible ultrasound transducer for integrated ECG monitoring of this invention uses a flexible substrate (i.e., a flexible circuit board) as its core, integrating various functional units (i.e., ultrasound functional units and ECG monitoring units) onto the same flexible substrate. When the device (i.e., the row-column addressable flexible ultrasound transducer for integrated ECG monitoring of this invention) is bent or stretched, the flexible substrate and encapsulation material can adapt to the deformation, thereby protecting the internal independent piezoelectric elements from damage. This achieves high overall flexibility and stretchability while ensuring the stable performance of each ultrasound unit (i.e., piezoelectric element). By adopting a row-column addressable structure (i.e., the row-direction metal electrode array contains multiple independent row electrodes, the top flexible electrode layer contains multiple independent column electrodes, and the piezoelectric material layer contains multiple independent piezoelectric elements distributed in multiple rows and columns, with piezoelectric elements in the same row corresponding to a row electrode and piezoelectric elements in the same column corresponding to a column electrode), the number of leads in an N×N array can be increased from N... 2 The number of channels is significantly reduced to 2N, significantly decreasing the system channel count and interconnection complexity, providing a feasible path for flexible integration with high array density. Furthermore, this invention integrates ultrasound functional units and ECG monitoring units on the same flexible substrate, achieving absolute synchronous acquisition of cardiac mechanical activity and electrophysiological signals in anatomical location and time, fundamentally solving the core problems of data asynchrony and positional mismatch inherent in traditional discrete devices. Based on this, the ECG sensing electrode array and ultrasound functional units work in coordination to achieve "acoustic-electrical" signal fusion: the ECG electrodes synchronously acquire electrophysiological signals during ultrasound imaging, ensuring temporal alignment and spatial consistency of the data. This design not only eliminates errors caused by multi-device docking but also, through flexible conformal bonding, enables the row-column addressable flexible ultrasound transducer integrating ECG monitoring to maintain stable coupling even under cardiac pulsation and respiratory deformation, effectively improving the ECG signal-to-noise ratio and ultrasound imaging resolution. In summary, the flexible ultrasound transducer proposed in this invention effectively improves the performance and integration of ultrasound imaging and electrocardiogram monitoring while achieving conformal fit to the curved surface of the human body and adapting to complex deformations. Furthermore, it can be mass-produced using the aforementioned fabrication method. This provides a more comprehensive and reliable data foundation for the early diagnosis of cardiovascular diseases, possessing significant clinical value and application prospects.

[0021] In contrast, this invention integrates ultrasound and ECG units into a flexible circuit board, and combines row and column addressing structure and precision cutting technology to fundamentally solve the processing problems caused by the difficulty of conformal bonding of rigid substrates and complex lead wires, providing a highly reliable foundation for wearable dynamic monitoring. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of a row-column addressable array flexible ultrasonic transducer integrating electrocardiogram monitoring in one embodiment of the present invention. Figure 2 For the present invention Figure 1 Cross-sectional view of a row-column addressable flexible ultrasound transducer integrating ECG monitoring in the illustrated embodiment; Figure 3 For the present invention Figure 1 An exploded view of the overall structure of the row-column addressable flexible ultrasound transducer integrating ECG monitoring in the embodiment shown. Figure 4 For the present invention Figure 1 The schematic diagram shows a top view of the flexible circuit board structure in the embodiment shown. Figure 5 For the present invention Figure 1 A side view (cross-sectional view) of the flexible circuit board of the embodiment shown. Figure 6 For the present invention Figure 1 An exploded view of the overall structure of the flexible circuit board in the embodiment shown. Figure 7 For the present invention Figure 1 The illustrated embodiment is a process flow diagram of the row and column addressing area array flexible ultrasound transducer integrating ECG monitoring. Figure 8(a) shows the first distribution pattern of the electrocardiogram sensing electrode array surrounding the ultrasound functional unit provided in the embodiment of the present invention; Figure 8(b) shows the second distribution pattern of the electrocardiogram sensing electrode array surrounding the ultrasound functional unit provided in the embodiment of the present invention; Figure 8(c) shows the third distribution pattern of the electrocardiogram sensing electrode array surrounding the ultrasound functional unit provided in the embodiment of the present invention; Figure 8(d) shows the fourth distribution pattern of the electrocardiogram sensing electrode array surrounding the ultrasound functional unit provided in the embodiment of the present invention; Figure 8(e) shows the fifth distribution pattern of the electrocardiogram sensing electrode array surrounding the ultrasound functional unit provided in the embodiment of the present invention; Figure 9 For the present invention Figure 1 A schematic diagram of the bending deformation structure of a row-column addressable flexible ultrasonic transducer for integrated electrocardiogram monitoring in the embodiment shown. Figure 10 This is a schematic diagram of the overall structure of a row-column addressable array flexible ultrasound transducer integrating electrocardiogram monitoring in another embodiment of the present invention. Figure 11 This invention Figure 10 An exploded view of the overall structure of the row-column addressable flexible ultrasound transducer integrating ECG monitoring in the embodiment shown. Figure 12(a) shows the present invention. Figure 10 The first distribution pattern of the electrocardiogram sensing electrode array on the surface of the ultrasound functional unit provided in the illustrated embodiment; Figure 12(b) shows the present invention. Figure 10 The second distribution pattern of the electrocardiogram sensing electrode array on the surface of the ultrasound functional unit provided in the illustrated embodiment; Figure 12(c) shows the present invention. Figure 10 The third distribution pattern of the electrocardiogram sensing electrode array on the surface of the ultrasound functional unit provided in the illustrated embodiment; Figure 12(d) shows the present invention. Figure 10 The fourth distribution pattern of the electrocardiogram sensing electrode array on the surface of the ultrasound functional unit provided in the illustrated embodiment; Figure 12(e) shows the present invention. Figure 10 The fifth distribution pattern of the electrocardiogram sensing electrode array on the surface of the ultrasound functional unit provided in the illustrated embodiment.

[0023] In the figure: 1-Flexible circuit board, 1-1-Row-oriented metal electrode array, 2-Piezoelectric material layer, 2-1-Piezoelectric element, 3-ECG sensing electrode, 4-Top flexible electrode layer, 5-Flexible acoustic backing layer, 6-Flexible acoustic matching layer, 7-Pad, 8-PI layer, 9-Electromagnetic shielding film, 10-Copper electrode, 11-Conductive adhesive, 12-Packaging structure. Detailed Implementation

[0024] The present invention will be further described clearly and in detail below with reference to specific embodiments and the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0025] To address the technical challenges of existing technologies, such as the difficulty of rigid ultrasound transducers conforming to the curved surface of the human chest, the high complexity of two-dimensional array leads, inability to adapt to cardiac pulsation and respiratory deformation, and the inability to synchronously monitor ECG and ultrasound signals, this invention proposes a row-column addressable array flexible ultrasound transducer with integrated ECG monitoring and its fabrication method. The flexible ultrasound transducer of this invention employs a flexible multilayer structure design and a row-column addressing scheme, enabling simultaneous acquisition of cardiac ultrasound imaging and ECG signals while ensuring conformal fit between the device and the human body and signal stability. This invention's row-column addressable array flexible ultrasound transducer innovatively adopts a flexible row-column addressable array ultrasound transducer structure, which can adaptively fit the curved surface of the chest, maintain stable coupling during long-term dynamic monitoring, and integrate ECG monitoring functions, thereby achieving synchronous and homogeneous monitoring of cardiac electromechanical activity, providing key hardware support for the development of wearable cardiac monitoring technology.

[0026] Reference Figures 1-7This embodiment integrates a row-column addressable array flexible ultrasound transducer for ECG monitoring, using a flexible circuit board 1 as the core carrier. The flexible circuit board 1 integrates an ultrasound functional unit and an ECG monitoring unit, and is protected by an encapsulation structure 12. The ultrasound functional unit is located in the central region of the flexible circuit board 1. Figures 1-3 Taking the orientation shown as an example, the upper surface of the flexible circuit board 1 is stacked from bottom to top with a piezoelectric material layer 2, a top flexible electrode layer 4, and a flexible acoustic matching layer 6, while the lower surface of the flexible circuit board 1 is provided with a flexible acoustic backing layer 5. The piezoelectric material layer 2 is divided into N rows and N columns of independent piezoelectric array elements 2-1. These piezoelectric array elements 2-1 can be row- and column-addressed through the row-direction metal electrode array and the column-direction metal electrode array on the flexible circuit board 1, thereby increasing the number of leads from N 2 Reducing it to 2N significantly lowers interconnect complexity.

[0027] The electrocardiogram (ECG) monitoring unit includes one or more ECG sensing electrodes 3, which are arranged in the following two forms: The first type: One or more electrocardiogram (ECG) sensing electrodes 3 are disposed on the extended area around the flexible circuit board 1. These ECG sensing electrodes 3 are distributed circumferentially in the ultrasound functional unit, and the distribution pattern can refer to... Figures 1-4 , Figures 6-9 In this configuration, the ECG sensing electrodes 3 are positioned as far as possible from the corners or edges of the flexible circuit board 1, away from the ultrasound radiation area, to avoid signal crosstalk.

[0028] The second form: The electrocardiogram sensing electrode 3 is placed on the flexible acoustic matching layer 6, and an electromagnetic shielding film 9 is placed between the electrocardiogram sensing electrode 3 and the flexible acoustic matching layer 6, and the distribution pattern can refer to... Figures 10-1 Form 2(e). In this configuration, by placing an electromagnetic shielding film 9 between the electrocardiogram sensing electrode 3 and the flexible acoustic matching layer 6, interference between ultrasound waves and the electrocardiogram sensing electrode 3 can be shielded.

[0029] In the above scheme, the ECG sensing electrode 3 is electrically connected to an ECG signal lead, through which ECG signals can be acquired synchronously. The encapsulation structure 12 material (i.e., flexible encapsulation material) can be made of polydimethylsiloxane (PDMS) material. The flexible encapsulation material covers the non-functional surfaces of the ultrasound functional unit and the ECG monitoring unit (i.e., the encapsulation structure completely covers the sidewalls and top of the ultrasound functional unit and covers the area of ​​the ECG monitoring unit except for the functional surface of the ECG sensing electrode), and completely fills the cutting gaps between the piezoelectric array elements, the row electrodes cut from the flexible circuit board 1, and the column electrodes cut from the top flexible electrode layer 4, ensuring the flexibility and reliability of the device. The encapsulation structure forms an exposure window at the position corresponding to the ECG sensing electrode, or is covered with a conductive hydrogel layer.

[0030] In this invention, the flexible circuit board 1 can be made of polyimide (PI) material, which has high flexibility and stretchability. The surface of the flexible circuit board 1 is covered with an electromagnetic shielding film 9, which can reduce electromagnetic interference. Specifically, the flexible circuit board 1 is covered with an electromagnetic shielding film except for the exposed conductive areas of the ECG sensing electrode array and the external interface. The row-direction metal electrode array and column-direction metal electrode array on the flexible circuit board 1 are realized by copper electrodes 10 and converge to the first external interface (such as a gold finger structure) for lead-out. The ECG signal lead is electrically isolated from the ultrasound addressing electrode and is led out through the second external interface (such as a gold finger structure). The first external interface and the second external interface are integrated in different edge areas of the flexible substrate.

[0031] In this invention, the piezoelectric material layer is fixedly connected to the row-oriented metal electrode array on the flexible circuit board 1 through a conductive adhesive layer; in the N×N piezoelectric array elements, each row of piezoelectric array elements shares the same bottom electrode, forming a row addressing electrode unit; the row-oriented metal electrode array includes N independent electrodes, and each independent electrode is electrically connected one-to-one with the common bottom electrode of a row of piezoelectric array elements.

[0032] In this invention, the top flexible electrode layer is formed into N independent column electrodes through a precision cutting process; the N independent column electrodes are respectively connected to each column of piezoelectric array elements in the piezoelectric material layer to form a column addressing electrode unit; the column direction metal electrode array includes N independent connection terminals, and the N independent column electrodes are electrically connected to the N independent connection terminals one-to-one.

[0033] In this invention, the ECG sensing electrode 3 can be fabricated using flexible conductive materials (such as graphene / carbon nanotube conductive ink) and has various morphological designs, as shown in Figures 8(a)-8(e). One typical form is an array structure distributed around the ultrasound functional unit. This structure not only helps optimize the coverage and stability of signal acquisition but also enables simultaneous acquisition of ECG and EMG signals through array distribution, or supports dynamic adjustment of the ECG acquisition position. Furthermore, the ECG sensing electrode 3 array can adopt different arrangements such as rectangular, concentric rings, or staggered arrangements to adapt to different body types and usage scenarios, ensuring close contact between the electrodes and the skin, thereby improving long-term wearing comfort and ECG signal acquisition quality. This surrounding distribution is not a simple mechanical combination but an optimized design based on the coordinated acquisition of acoustic and electrical signals: the array layout ensures that the ECG electrodes and the ultrasound radiation area do not interfere with each other, while the close contact reduces signal transmission delay, achieving millisecond-level synchronization of electromechanical activities. This collaborative working mechanism effectively avoids motion artifacts caused by the relative displacement of the electrodes and probe in traditional solutions, significantly improving the accuracy of long-term dynamic monitoring.

[0034] In this invention, the electrocardiogram sensing electrode 3 can be fabricated using flexible conductive materials (such as graphene / carbon nanotube conductive ink) and has various morphological designs, see [link to relevant documentation]. Figures 10-1 2(e) can be a single piece of electrocardiogram sensing electrode 3 placed on top of the flexible acoustic matching layer 6 with an electromagnetic shielding film 9 placed between them. Alternatively, multiple pieces (four in Figure 12(b), three in Figure 12(c), six in Figure 12(d), and nine in Figure 12(e)) of electrocardiogram sensing electrodes 3 can be placed on top of the flexible acoustic matching layer 6 with an electromagnetic shielding film 9 placed between them. Of course, those skilled in the art can also set other numbers and shapes of electrocardiogram sensing electrodes 3 according to actual needs, which will not be elaborated upon in this invention.

[0035] In this invention, the electrocardiogram sensing electrode 3 can be integrally formed with a flexible substrate, and the material of the electrocardiogram sensing electrode 3 can be the metal wiring layer of the flexible substrate and surface-plated with gold or silver.

[0036] Figure 4 The top view of the flexible circuit board 1 is shown. The flexible circuit board 1 has a layout of row-oriented metal electrode arrays, column-oriented metal electrode arrays, ECG sensing electrode pads, and external interfaces. The row-oriented metal electrode array contains N independent row electrodes, each of which shares a bottom electrode connection with a row of piezoelectric array elements 2-1; the column-oriented metal electrode array also contains N independent connection terminals for conducting with the column electrodes of the top flexible electrode layer 4.

[0037] Figure 5 The diagram shows a side cross-section of the flexible circuit board 1, illustrating its multilayer structure: a PI layer 8 serves as the substrate, copper electrodes 10 form the wiring layer, an electromagnetic shielding film 9 covers the non-conductive areas, and the locations of the ECG sensing electrode pads. This design ensures the insulation of the electrodes and signal integrity.

[0038] The piezoelectric material layer 2 is composed of a piezoelectric functional material, which can be selected from any of the following: piezoelectric ceramics (such as PZT), piezoelectric single crystals, piezoelectric polymers, or piezoelectric composite materials. It is fixedly connected to the row-oriented metal electrode array through a conductive silver paste 11 adhesive layer. The piezoelectric array elements are formed by a precision cutting process, and each row of array elements shares the same bottom electrode, forming a row addressing electrode unit. The top flexible electrode layer 4 is made of a flexible conductive material (such as a transparent conductive film of silver nanowires, conductive tape, or conductive fabric; the conductive tape includes a composite structure of a carbon-based conductive layer and a pressure-sensitive adhesive or a transparent conductive film of silver nanowires). It is cut to form N independent column electrodes, and each column electrode is connected to a corresponding column of piezoelectric array elements, forming a column addressing electrode unit.

[0039] Figure 3An exploded view of the transducer's overall structure clearly shows the stacking order of each layer: starting with the flexible circuit board 1, the layers are arranged in sequence as follows: piezoelectric material layer 2, ECG sensing electrode 3, top flexible electrode layer 4, flexible acoustic backing layer 5, flexible acoustic matching layer 6, and packaging structure 12. This multi-layer integrated design ensures that the device maintains stable performance under bending deformation.

[0040] The flexible acoustic backing layer 5 is composed of epoxy resin filled with tungsten powder, which has high damping characteristics and is used to absorb reverse sound waves. The flexible acoustic matching layer 6 is one or more flexible polymer films (such as polyurethane) with specific acoustic impedance, which matches the acoustic impedance of human tissue to optimize sound wave transmission. The encapsulation structure 12 fills the gaps between the array elements with PDMS material and covers the surface, and opens windows or covers conductive hydrogel at the ECG sensing electrodes 3 to maintain electrical connection.

[0041] Based on the above scheme, this embodiment integrates a row-column addressable flexible ultrasound transducer for ECG monitoring, including a signal detection unit encapsulated in a flexible packaging material. The signal detection unit includes a flexible circuit board 1 and an ultrasound functional unit and an ECG monitoring unit disposed on the flexible circuit board 1. The upper side (or front side) of the flexible circuit board 1 has a row-oriented metal electrode array 1-1, where the row direction is... Figure 7 As shown in the front-to-back direction perpendicular to the paper, the ultrasonic functional unit includes a piezoelectric material layer 2, a top flexible electrode layer 4, a flexible acoustic backing layer 5, and a flexible acoustic matching layer 6. The piezoelectric material layer 2 is electrically connected to the row-direction metal electrode array 1-1. The flexible acoustic backing layer 5 is disposed on the side of the flexible circuit board 1 opposite to the piezoelectric material layer 2 (i.e., the flexible acoustic backing layer 5 is disposed on the lower side (or back side) of the flexible circuit board 1). The top flexible electrode layer 4 is disposed on the upper side of the piezoelectric material layer 2 and is electrically connected to it. The flexible acoustic matching layer 6 is disposed on the upper side of the top flexible electrode layer 4. The row-direction metal electrode array 1-1 contains multiple independent row electrodes, and the top flexible electrode layer 4 contains multiple independent column electrodes. The length direction (also referred to as the column direction) of the column electrodes is... Figure 7As shown in the left-right direction, the piezoelectric material layer 2 includes multiple independent piezoelectric array elements 2-1 distributed in multiple rows and columns. In this embodiment, the piezoelectric array elements 2-1 are distributed in an N×N row and column form. Similarly, the number of row electrodes and column electrodes is N. The piezoelectric array elements 2-1 located in the same row are electrically connected to a row electrode, and the piezoelectric array elements 2-1 located in the same column are electrically connected to a column electrode. That is, a row electrode is electrically connected to the lower end of a row of piezoelectric array elements 2-1, and a column electrode is electrically connected to the upper end of a column of piezoelectric array elements 2-1. The size of the piezoelectric array elements 2-1 along the row and column directions is 1 mm. The row direction metal electrode array 1-1 and the top flexible electrode layer 4 are led out through the first external interface on the flexible circuit board 1. The electrocardiogram sensing electrode 3 is electrically connected to the electrocardiogram signal lead. The electrocardiogram signal lead is electrically isolated from the row direction metal electrode array 1-1 and the top flexible electrode layer 4 on the flexible circuit board 1. The electrocardiogram signal lead is led out through the second external interface on the flexible circuit board 1. Both the first external interface and the second external interface are independent gold finger structures, integrated in different areas of the flexible circuit board 1. The surfaces of the flexible acoustic backing layer 5 and the piezoelectric material layer 2 on the flexible circuit board 1, except for the row-direction metal electrode array 1-1, the top flexible electrode layer 4, the ECG sensing electrode area, and the exposed conductive areas of the second external interface, are all covered with an electromagnetic shielding film 9. The ECG monitoring unit includes ECG sensing electrodes 3, and the flexible circuit board 1 has four ECG sensing electrodes 3 on the outer periphery of the piezoelectric material layer 2. The flexible encapsulation material has exposure windows on the functional surfaces of the ECG sensing electrodes 3, and the gaps in the row-direction metal electrode array 1-1, the piezoelectric material layer 2, and the top flexible electrode layer 4 are filled with the flexible encapsulation material.

[0042] Reference Figure 1 , Figure 2 , Figure 7 The present invention discloses a method for fabricating a row-column addressable flexible ultrasound transducer for integrated electrocardiogram monitoring, comprising the following steps. This fabrication process uses a flexible circuit board as the core carrier, and achieves high-density array element integration and device structural reliability through precision cutting, lamination, and flexible packaging processes. The specific steps are as follows: S1. Substrate pretreatment: Isopropanol is used to ultrasonically clean the surface of the row direction metal electrode array 1-1 of the flexible circuit board 1, the piezoelectric material connection surface for preparing the piezoelectric material layer 2, and the bonding surface of the electrocardiogram sensing electrode 3. The cleaning time is 8-12 minutes to ensure that there are no contaminants on the surface and improve the subsequent bonding quality.

[0043] S2. Piezoelectric Layer Bonding and Array Forming: A conductive silver paste layer with a thickness of 15±3μm is uniformly coated on the surface of the row-direction metal electrode array on the front side of the flexible circuit board. Simultaneously, a silver paste layer of the same thickness is coated on the piezoelectric material bonding surface. The piezoelectric material layer is then precisely positioned and bonded to the flexible circuit board, and cured at 80±2℃ for 115-125 minutes until the conductive silver paste solidifies, completing the bonding. Next, the piezoelectric material layer is cut along the row direction using a diamond dicing machine at a speed of 30,000 rpm and a feed rate of 0.5 mm / s, forming a 50±5μm wide kerf, thus dividing the piezoelectric material layer into N rows and N columns of independent piezoelectric array elements. This high-precision processing effectively suppresses signal crosstalk between array elements, significantly improves the overall performance consistency of the array, and better meets the requirements of flexible integrated devices in terms of structural adaptability and reliability, outperforming traditional cutting methods.

[0044] S3. Row electrode isolation: A femtosecond laser (wavelength 1030nm, pulse width 350fs) is used to cut the row-direction metal electrodes from the back of the flexible circuit board 1 along the row gaps in the piezoelectric material layer 2. The laser power is set to 5±0.5W and the scanning speed is 10mm / s to electrically isolate each row of electrodes from each other. After cutting, the electrodes are ultrasonically cleaned with 99.9% ethanol for 5 minutes to remove cutting residues and ensure the reliability of electrode insulation.

[0045] S4. Forming of the top flexible electrode layer 4 and column electrodes: A flexible conductive film (such as a transparent conductive film made of silver nanowires) is covered on the surface of the piezoelectric element. A pressure-sensitive adhesive layer is used to simultaneously adhere the conductive film to all piezoelectric elements and the column-oriented metal electrodes of the flexible circuit board. Subsequently, the flexible conductive film is cut along the column gaps in the piezoelectric material layer 2 using a dicing process with the same parameters as in S3. The dicing wheel rotates at 30,000 rpm, and the feed speed is 0.5 mm / s, forming N independent column electrodes. Each column electrode is connected to the corresponding column-oriented metal electrode on the flexible circuit board 1 through the pressure-sensitive adhesive layer on the lower surface of the conductive film, completing the construction of the column-addressing electrode unit. This process, through the transfer and cutting of the top flexible conductive layer, ensures a reliable electrical connection between the column electrodes and the piezoelectric elements, simplifying the electrode interconnection structure and effectively reducing the risk of failure caused by dense lead wires.

[0046] S5. Gap filling: Flexible materials (such as polydimethylsiloxane prepolymer) are used to fill the cut gaps in the row-oriented metal electrode array 1-1, the piezoelectric material layer 2, and the top flexible electrode layer 4. The material is injected through a dispensing process to ensure that the gaps are completely filled. Then, it is cured at 65°C for 60 minutes to enhance structural integrity and avoid acoustic interference.

[0047] S6. Forming of flexible acoustic backing layer 5: An acoustic backing material is coated or pressed onto the back of the central region of the flexible circuit board 1. The material is made of epoxy resin filled with tungsten powder, with a coating thickness of 1.0±0.1mm, and cured at 80°C for 90 minutes to form a high-damping flexible acoustic backing layer for absorbing reverse sound waves and increasing bandwidth.

[0048] S7. Attachment of flexible acoustic matching layer 6: Attach a flexible acoustic matching layer 6 to the surface of the top flexible electrode layer 4. The flexible acoustic matching layer 6 is one or more flexible polymer films (such as polyurethane), with acoustic impedance values ​​matching human tissue. During attachment, a rolling process is used to ensure no air bubbles, and the thickness is controlled at 0.2±0.05mm to optimize sound wave transmission efficiency.

[0049] S8. Electrode Bonding: A conductive adhesive (such as conductive silver paste) is applied to the electrocardiogram (ECG) sensing electrode pads on the front side of the flexible circuit board 1, and the ECG sensing electrode (such as a silver-plated flexible electrode) is bonded to it. The bonding is then cured at 60°C for 30 minutes to ensure reliable electrical connection. The ECG sensing electrodes are arranged in the extended area around the flexible circuit board, away from the ultrasound radiation area, thus minimizing acoustic-electrical signal crosstalk in the physical layout. To achieve coordinated acquisition of acoustic and electrical signals, the system adopts a synchronous working mechanism: when the ultrasound array element emits or receives sound waves, the ECG electrodes synchronously acquire electrophysiological signals. The flexible circuit board has a dedicated electrical isolation design to ensure that the two signals do not interfere with each other during acquisition. This design enables the system to stably output high-fidelity synchronous data even under flexible deformation conditions, improving the reliability of dynamic monitoring.

[0050] S9. Encapsulation Structure Molding: The semi-finished product obtained in step S8 is placed in the mold cavity, and a PDMS prepolymer mixture with a mass ratio of 10:1 is injected until the non-functional surface of the device is completely immersed. Vacuum is applied to a residual pressure ≤50Pa and maintained for 60 minutes to remove air bubbles. Subsequently, it is transferred to a 65℃ oven for curing for 120 minutes to form an encapsulation layer with a thickness of 0.3±0.05mm. The encapsulation structure has windows or is covered with a conductive hydrogel layer at the corresponding ECG sensing electrodes to maintain the ECG signal acquisition function. This design provides effective protection for the electrodes and ensures stable contact with the skin, thereby maintaining continuous ECG signal acquisition during ultrasound scanning and avoiding data interruption. While ensuring mechanical flexibility, the encapsulation structure further enhances the reliability and wearing comfort of the device during long-term dynamic monitoring.

[0051] This fabrication method, through the above steps, achieves the integrated integration of the ultrasound functional unit and the electrocardiogram monitoring unit. The device is resistant to bending and tensile deformation (see...). Figure 9 It can maintain stable performance even under certain conditions, making it suitable for wearable cardiac monitoring scenarios.

[0052] Compared to existing technologies, this invention, using a flexible circuit board as its core carrier, offers the following processing advantages: Precision cutting technology enables micron-level precision control of array element spacing, significantly improving imaging resolution; integrated fabrication of row and column addressing electrodes via the flexible circuit board effectively reduces lead wire errors, superior to traditional step-by-step electrode bonding processes; simultaneously, the use of PDMS material for encapsulation balances structural flexibility and acoustic isolation performance, reducing the risk of array element failure under deformation. This design achieves integrated integration of the ultrasound functional unit and the ECG monitoring unit, simplifying the traditional multi-component docking process into a continuous lamination process, reducing assembly errors and significantly improving processing efficiency and device stability under bending deformation environments.

[0053] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An integrated electrocardiographic monitoring row-column addressed matrix flexible ultrasound transducer, characterized in that, The signal detection unit is encapsulated in a flexible encapsulating material, and the signal detection unit comprises a flexible circuit board (1) and an ultrasonic functional unit and an electrocardio monitoring unit arranged on the flexible circuit board (1), the flexible circuit board (1) has a row direction metal electrode array (1-1), the ultrasonic functional unit comprises a piezoelectric material layer (2), a top flexible electrode layer (4), a flexible acoustic backing layer (5) and a flexible acoustic matching layer (6), the piezoelectric material layer (2) is in conductive connection with the row direction metal electrode array (1-1), the flexible acoustic backing layer (5) is arranged on the side of the flexible circuit board (1) opposite to the piezoelectric material layer (2), the top flexible electrode layer (4) is arranged on the side of the piezoelectric material layer (2) opposite to the row direction metal electrode array (1-1) and is in conductive connection with the piezoelectric material layer (2), the flexible acoustic matching layer (6) is arranged on the top flexible electrode layer (4) on the side opposite to the piezoelectric material layer (2), the row direction metal electrode array (1-1) comprises a plurality of independent row electrodes, the top flexible electrode layer (4) comprises a plurality of independent column electrodes, and the piezoelectric material layer (2) comprises a plurality of independent piezoelectric elements (2-1) distributed in multiple rows and multiple columns, the piezoelectric elements (2-1) located in the same row are in conductive connection with a row electrode in correspondence, and the piezoelectric elements (2-1) located in the same column are in conductive connection with a column electrode in correspondence; the electrocardio monitoring unit comprises an electrocardio sensing electrode (3) for detecting an electrocardio sensing signal.

2. The row-column addressing area array flexible ultrasonic transducer integrated with electrocardio monitoring according to claim 1, characterized in that: the electrocardio sensing electrode (3) is arranged on the flexible circuit board (1) and located at the periphery of the piezoelectric material layer (2); alternatively, the electrocardio sensing electrode (3) is arranged on the flexible acoustic matching layer (6), and an electromagnetic shielding film (9) is arranged between the electrocardio sensing electrode (3) and the flexible acoustic matching layer (6).

3. The integrated ECG-monitored row-column addressed matrix flexible ultrasound transducer of claim 1, wherein, The flexible encapsulating material has an exposed window on the functional surface of the electrocardio sensing electrode (3), and the gaps in the row direction metal electrode array (1-1), the piezoelectric material layer (2) and the top flexible electrode layer (4) are all filled with the flexible encapsulating material.

4. The integrated ECG-monitored row-column addressed matrix flexible ultrasound transducer of claim 3, wherein, The functional surface of the electrocardio sensing electrode (3) is provided with a conductive hydrogel layer.

5. The integrated ECG-monitored row-column addressed matrix flexible ultrasound transducer of claim 1, wherein, The row direction metal electrode array (1-1) and the top flexible electrode layer (4) are led out through a first external interface on the flexible circuit board (1); the electrocardio sensing electrode (3) is electrically connected with an electrocardio signal lead, the electrocardio signal lead is electrically isolated from the row direction metal electrode array (1-1) and the top flexible electrode layer (4) on the flexible circuit board (1), and the electrocardio signal lead is led out through a second external interface on the flexible circuit board (1).

6. The integrated ECG-monitored row-column addressed matrix flexible ultrasound transducer of claim 5, wherein, Among the surface of the flexible circuit board (1) on which the flexible acoustic backing layer (5) is arranged and the surface of the flexible circuit board (1) on which the piezoelectric material layer (2) is arranged, except for the row direction metal electrode array (1-1), the top flexible electrode layer (4), the electrocardio sensing electrode area, the second external interface and the exposed conductive area of the second external interface, all are covered with an electromagnetic shielding film (9).

7. The integrated ECG-monitored row-column addressed matrix flexible ultrasound transducer of claim 1, wherein, The ECG sensing electrodes (3) are arranged in a plurality of numbers, the plurality of ECG sensing electrodes (3) surround the piezoelectric material layer (2), and the ECG sensing electrodes (1) are arranged at the corners or edges of the extending area of the flexible circuit board (1) and are away from the sound wave radiation area of the ultrasonic functional unit.

8. The integrated ECG-monitored row-column addressed matrix flexible ultrasound transducer of claim 1, wherein, The flexible acoustic backing layer (5) is made of high-damping flexible material, the high-damping flexible material is made of epoxy resin filled with tungsten powder or aluminum oxide powder, or made of silicone rubber filled with tungsten powder or aluminum oxide powder; The flexible acoustic matching layer (6) is made of flexible polymer film with specific acoustic impedance, wherein the flexible polymer film is made of polyurethane film; The piezoelectric array element (2-1) is made of any one of piezoelectric ceramic, piezoelectric single crystal, piezoelectric polymer or piezoelectric composite material, and the size of the piezoelectric array element (2-1) along the row direction and the column direction is not greater than 1mm; The piezoelectric array element (2-1) is fixedly connected with the row electrodes of the row direction metal electrode array (1-1) through the conductive silver paste adhesive layer (11); The flexible packaging material is polydimethylsiloxane.

9. The integrated ECG-monitored row-column addressed matrix flexible ultrasonic transducer of claim 1, wherein, The material of the top flexible electrode layer (4) is conductive fabric or conductive tape; wherein the conductive fabric includes silver-coated nylon fiber or copper-nickel alloy wire mixed structure, and the conductive tape includes carbon-based conductive layer and pressure-sensitive adhesive composite structure or silver nanowire transparent conductive film.

10. The method of claim 1-9 for fabricating an integrated ECG-monitored row-column addressed matrix flexible ultrasound transducer, characterized in that, The method comprises the following steps: S1. substrate pretreatment: ultrasonic cleaning is performed on the surface of the row direction metal electrode array (1-1) of the flexible circuit board (1), the piezoelectric material connecting surface for preparing the piezoelectric material layer (2), and the ECG sensing electrode (3) connecting surface by using isopropyl alcohol; S2. piezoelectric layer bonding and row array element forming: a conductive adhesive is coated on the surface of the row direction metal electrode array (1-1) on the front of the flexible circuit board 1, the piezoelectric material for preparing the piezoelectric material layer (2) is pasted on the surface of the conductive adhesive, after the conductive adhesive is cured, the piezoelectric material layer is divided into a plurality of independent piezoelectric array elements (2-1) distributed in multiple rows and multiple columns; S3. row electrode isolation: the row direction metal electrode array (1-1) on the flexible circuit board (1) is cut along the row gap in the piezoelectric material layer (2) to form a plurality of mutually electrically isolated and independent row electrodes; S4. top flexible electrode layer (4) integration and column electrode forming: the top flexible electrode layer material is connected to the surface of the piezoelectric material layer (2), and then the top flexible electrode layer material is divided along the column gap in the piezoelectric material layer (2) to obtain a plurality of independent column electrodes, form the top flexible electrode layer (4), and make the column electrodes electrically connected with the column direction metal electrode array on the flexible circuit board (1); S5. gap filling: the flexible packaging material is used to fill the gaps in the row direction metal electrode array (1-1), the piezoelectric material layer (2) and the top flexible electrode layer (4); S6. flexible acoustic backing layer (5) forming: acoustic backing material is coated or pressed on the surface of the side opposite to the piezoelectric material layer (2) on the flexible circuit board (1) and is cured to form the flexible acoustic backing layer (5). S7. Flexible acoustic matching layer 6 attachment: Attach flexible acoustic matching layer (6) on the surface of the top flexible electrode layer (4); S8. ECG electrode bonding: Apply conductive adhesive on the pads on the outer periphery of the piezoelectric material layer (2) on the flexible circuit board (1) for mounting the ECG sensing electrode (3), then attach the ECG sensing electrode (3) and cure the conductive adhesive; S9. Encapsulation structure forming: Use liquid flexible encapsulation material to coat the non-functional surface of the entire signal detection unit by dispensing, molding or vacuum infusion process, and perform windowing or covering conductive hydrogel treatment on the functional area of the ECG sensing electrode (3), and then solidify to form an encapsulation structure.

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