Flexible wearable patch

Abstract

The invention discloses a flexible wearable patch which comprises a flexible ultrasonic transducer and a flexible stretchable electrode connected with the flexible ultrasonic transducer in a pasted mode. The flexible ultrasonic transducer comprises a flexible backing layer, a first flexible printed circuit board layer and a flexible acoustic stacking layer arranged on the first flexible printed circuit board layer which are stacked in sequence; the area, not provided with the flexible acoustic stacking layer, of the first flexible printed circuit board layer is connected with the flexible stretchable electrode in an adhesive mode. The flexible wearable patch further comprises a second flexible printed circuit board layer; the flexible stretchable electrode is electrically connected with the second flexible printed circuit board layer. According to the flexible wearable patch provided by the invention, ultrasonic imaging and electric signal monitoring are integrated, and synchronous in-situ monitoring of ultrasonic imaging and electric signals can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of bio - interface sensing, and particularly relates to a flexible wearable patch. Background Art

[0002] Neuromuscular diseases (NMDs) cause muscle weakness and movement disorders. Traditional diagnostic methods such as electromyography (EMG) and ultrasound imaging mainly target different aspects of muscles, but cannot achieve comprehensive evaluation. Electromyography is used to monitor the electrophysiological activities of muscles, while ultrasound imaging can provide structural information of muscles. Although flexible electronics technology has made progress in these two fields in recent years, the existing technologies still face many challenges, such as unstable contact caused by skin deformation, signal synchronization problems, and the inability of existing devices to meet the needs of long - term and dynamic monitoring.

[0003] For electrophysiological signal monitoring, the current research focus is on flexible electrode arrays, especially electrodes based on highly flexible materials such as flexible stretchable films and ionic gels. These materials can effectively adapt to skin deformation, reduce the problem of poor contact caused by movement or muscle contraction, and ensure signal stability. In addition, the research on bionic three - dimensional structured e - skins shows the potential of constructing complex flexible sensing systems through decoupled sensing capabilities. These systems mimic the spatial distribution of mechanoreceptors in human skin, further improving the accuracy and functionality of wearable sensors.

[0004] For ultrasound imaging technology, commercial ultrasound devices are usually rigid and bulky, not suitable for long - term, continuous and stable monitoring. Usually, the user must hold the rigid ultrasound device and apply a certain pressure to ensure good contact with the skin to obtain clear tissue imaging. Although this method performs well in deep tissue imaging, applying pressure may cause muscle deformation, thus affecting the accurate reflection of the true structural features during muscle imaging. Therefore, the research focus has gradually shifted to the development of flexible and stretchable ultrasound probes to replace traditional rigid probes for blood pressure, blood flow detection and structural imaging. These sensors can adapt to the skin surface and achieve dynamic imaging, especially suitable for the structural monitoring of muscles. However, the existing ultrasound imaging technology often faces the problem that skin deformation affects the imaging quality, especially during dynamic movement, and the imaging quality will be limited to a certain extent.

[0005] In addition, evaluating only through monitoring either structure or function unilaterally often leads to incomplete information acquisition and may even cause misdiagnosis. Generally speaking, the existing technologies have not achieved the effective integration of electrophysiology and ultrasound imaging, limiting the comprehensive diagnosis and detection of muscle health conditions. Therefore, there is a lack of a dual - mode flexible sensing patch that can synchronously detect electrophysiological signals and muscle structure changes.

[0006] In the prior art, electrophysiological monitoring and ultrasonic imaging are usually carried out separately, which are used to detect the functional signals (such as electromyogram signals) and structural signals (such as muscle thickness, morphology, etc.) of muscles respectively. However, there are several key problems with this single-modal monitoring: (1) Lack of dual-modal synchronous monitoring: Most of the prior art can only obtain electrophysiological signals or ultrasonic images separately, and cannot simultaneously and real-time synchronously monitor electrophysiological and ultrasonic signals. This means that the structural and functional information of muscles cannot be directly and in-situ synchronously obtained, resulting in an insufficient comprehensive evaluation of diseases or health status and affecting the accuracy of diagnosis. If directly combined, it will lead to a relatively large system volume, difficult to wear, strong rigidity, non-conforming to the dynamically deformed skin, and difficult to image.

[0007] (2) Influence of skin deformation on monitoring accuracy: In the case of human movement or skin stretching, electrophysiological electrodes are easily affected by skin deformation, resulting in signal distortion. At the same time, traditional ultrasonic devices require relatively stable contact, and long-term wearing or dynamic movement will affect the accuracy of ultrasonic signals. In the prior art, during dynamic movement, especially when the skin deformation exceeds a certain range, the stability and reliability of signals cannot be effectively maintained.

[0008] (3) Lack of integrated design and compatibility: Currently, electrophysiological electrodes and ultrasonic sensors are often operated independently and cannot be effectively integrated. In order to achieve the best monitoring effect, multiple devices need to be used simultaneously, which not only increases the complexity of operation but also limits the portability and comfort of the system. Especially in scenarios that require long-term wearing and dynamic monitoring, the prior art cannot meet the requirements of integration, flexibility, and stability. Summary of the Invention

[0009] To solve the above technical problems, the present invention provides a flexible wearable patch, which integrates a flexible ultrasonic transducer (FUT) and a flexible stretchable electrode, improves the overall wearability of the device while maintaining high-quality imaging, makes it more suitable for long-term wearing, ensures the stability of electromyogram signal acquisition, weakens the influence of deformation on the imaging of the ultrasonic transducer, and enables the entire system to have good flexibility and conformability.

[0010] To achieve the above object, the technical solution of the present invention is as follows: The present invention provides a flexible wearable patch, including a flexible ultrasonic transducer and a flexible stretchable electrode adhesively connected thereto; The flexible ultrasonic transducer includes a flexible backing layer, a first flexible printed circuit board layer, and a flexible acoustic stack layer sequentially stacked; the area of the first flexible printed circuit board layer where the flexible acoustic stack layer is not provided is adhesively connected to the flexible stretchable electrode; The flexible wearable patch further includes a second flexible printed circuit board layer; the flexible stretchable electrode is electrically connected to the second flexible printed circuit board layer.

[0011] As a preferred embodiment, the flexible acoustic stack layer includes a plurality of acoustic stack units; the flexible acoustic stack layer includes a piezoelectric material layer, a first matching layer, and a second matching layer which are sequentially stacked; wherein, the second matching layer faces the flexible stretchable electrode.

[0012] As a preferred embodiment, a signal electrode and a ground electrode are provided on the piezoelectric material layer, and the signal electrode and the ground electrode are respectively provided on the upper / lower surface or the lower / upper surface of the piezoelectric material layer; the signal electrode and the ground electrode are respectively electrically connected to the corresponding electrodes on the first flexible printed circuit board layer.

[0013] As a preferred embodiment, the signal electrode and the ground electrode are Cr / Au electrodes; the Cr / Au electrode includes a Cr layer connected to the piezoelectric material layer and an Au layer provided on the Cr layer; in the technical solution of the present invention, the Cr layer is used to improve the adhesion of the Au layer; the Au layer provides conductivity.

[0014] And / or, the first matching layer is an epoxy resin doped with alumina; the second matching layer is an epoxy resin; the types of the epoxy resins of the first matching layer and the second matching layer are the same.

[0015] And / or, the flexible backing layer is polydimethylsiloxane (PDMS) doped with alumina and hollow glass microspheres.

[0016] As a preferred embodiment, the preparation method of the flexible ultrasonic transducer includes the following steps: (1) Cut the piezoelectric material into a piezoelectric unit array by a cutting method, and fill the gaps of the piezoelectric unit array with epoxy resin; prepare a signal electrode or a ground electrode on the filled upper surface, and sequentially prepare a first matching layer and a second matching layer on the signal electrode or the ground electrode; cut a groove on the filled lower surface to re-form a piezoelectric unit array, fill the groove with polydimethylsiloxane, and prepare a ground electrode or a signal electrode on the filled surface to obtain a flexible acoustic stack layer having a plurality of acoustic stack units; (2) Cure and bond the surface of the flexible acoustic stack layer away from the second matching layer to the first flexible printed circuit board layer with epoxy resin; electrically connect the signal electrode and the ground electrode to the corresponding electrodes on the first flexible printed circuit board layer; (3) Prepare a flexible backing layer on the other side of the first flexible printed circuit board layer.

[0017] As a preferred embodiment, the flexible stretchable electrode includes a flexible stretchable substrate and a conductive layer disposed on the flexible stretchable substrate.

[0018] As a preferred embodiment, the flexible stretchable substrate is selected from any one of silica gel, styrene-ethylene-butadiene-styrene block copolymer (SEBS), and polydimethylsiloxane.

[0019] And / or, the conductive layer is selected from any one of gold, silver, and platinum; the conductive layer is a patterned conductive layer.

[0020] As a preferred embodiment, the conductive layer of the flexible stretchable electrode is electrically connected to the second flexible printed circuit board layer through a liquid metal.

[0021] As a preferred embodiment, the area on the first flexible printed circuit board layer where the flexible acoustic stack layer is not provided is adhesively connected to the flexible stretchable substrate of the flexible stretchable electrode through a double-sided tape.

[0022] As a preferred embodiment, the flexible stretchable substrate is also subjected to plasma treatment before being adhered with the double-sided tape.

[0023] Compared with the prior art, the present invention has the following beneficial effects: The flexible wearable patch provided by the present invention integrates ultrasonic imaging and electrical signal monitoring, realizing synchronous in-situ monitoring of ultrasonic imaging and electrical signals. Among them, the flexible stretchable electrode has high stretchability and low impedance, which can ensure stable myoelectric signal acquisition. It can also be used as a stress release layer to relieve skin deformation stress, ensuring that the sensor can still maintain stable monitoring ability under dynamic movements (such as bending the arm, bending over, turning the head, etc.), thereby maintaining the imaging stability of the ultrasonic transducer. Description of the Drawings

[0024] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, the present invention and its features, shapes, and advantages will become more obvious. The same reference numerals indicate the same parts in all the drawings. The drawings are not deliberately drawn to scale, and the emphasis is on showing the gist of the present invention.

[0025] Figure 1 It is a schematic structural diagram of the flexible wearable patch in Embodiment 1 of the present invention.

[0026] Figure 2 is Figure 1 an enlarged view of the structure at location A of the flexible wearable patch.

[0027] Figure 3 is an image of the muscle structure formed by a commercial ultrasonic probe and the flexible ultrasonic probe prepared from the flexible wearable patch in Embodiment 1 of the present invention.

[0028] Figure 4 It is a muscle compression rate map caused by imaging of muscle structure using a commercial ultrasonic probe and a flexible ultrasonic probe prepared from the flexible wearable patch in Embodiment 1 of the present invention.

[0029] Figure 5 It is the imaging of the brachioradialis muscle in the forearm, erector spinae muscle in the back, and sternocleidomastoid muscle in the neck during deformation using the flexible ultrasonic probe prepared from the flexible wearable patch in Embodiment 1 of the present invention.

[0030] Figure 6a and Figure 6b They are diagrams of the adhesion states of the flexible ultrasonic probes prepared from the flexible wearable patches with and without flexible stretchable electrodes on the neck skin, respectively.

[0031] Figure 7 It is a diagram of the analysis results of the ultrasonic structure and electromyogram signals for the bimodal synchronous monitoring of the brachioradialis muscle in the forearm using the flexible ultrasonic probe prepared from the flexible wearable patch in Embodiment 1 of the present invention.

[0032] Figure 8 It is a diagram of the results of the structural-functional synchronous monitoring of children with Charcot-Marie-Tooth disease (CMT) using the flexible ultrasonic probe prepared from the flexible wearable patch in Embodiment 1 of the present invention. Detailed implementation manners

[0033] Next, in combination with the accompanying drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Therefore, the detailed descriptions of the embodiments of the present invention provided in the following drawings are not intended to limit the scope of the claimed invention, but merely represent selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present invention.

[0034] It should be understood that when terms such as "include" and / or "comprise" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] In the description of the present invention, it should be noted that when terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0036] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, terms such as "installation", "connection", and "coupling" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0037] In the present invention, unless otherwise specified, all devices, raw materials, etc. can be purchased from the market or are commonly used in this industry. The methods in the following embodiments are all conventional methods in this field unless otherwise specified.

[0038] Aiming at the technical problem that it is difficult to integrate electrophysiological electrodes and ultrasonic sensors in the prior art, the present invention provides a flexible wearable patch, the structure of which is as Figure 1-2 shown, including a flexible ultrasonic transducer and a flexible stretchable electrode adhesively connected thereto; The flexible ultrasonic transducer includes a flexible backing layer, a first flexible printed circuit board layer, and a flexible acoustic stack layer sequentially stacked; the area of the first flexible printed circuit board layer where the flexible acoustic stack layer is not provided is adhesively connected to the flexible stretchable electrode; The flexible wearable patch further includes a second flexible printed circuit board layer; the flexible stretchable electrode is electrically connected to the second flexible printed circuit board layer.

[0039] In some specific embodiments, the thickness of the flexible ultrasonic transducer is 1.95 - 3.2 mm; the thickness of the flexible backing layer is 1.5 - 2.5 mm; the thickness of the flexible printed circuit board layer is 0.05 - 0.2 mm; the thickness of the flexible acoustic stack layer is 0.4 - 0.5 mm.

[0040] In some specific embodiments, the first flexible printed circuit board layer and / or the second flexible printed circuit board layer is a polyimide copper clad laminate.

[0041] Furthermore, the flexible acoustic stack layer includes a plurality of acoustic stack units; the flexible acoustic stack layer includes a piezoelectric material layer, a first matching layer, and a second matching layer sequentially stacked; wherein, the second matching layer faces the flexible stretchable electrode.

[0042] In some specific embodiments, the thickness of the piezoelectric material layer is 0.2 - 0.3 mm; the thickness of the first matching layer is 0.1 - 0.2 mm; the thickness of the second matching layer is 0.1 - 0.2 mm.

[0043] In some specific embodiments, the piezoelectric material layer is a 2-2 type piezoelectric composite material, which is prepared from a piezoelectric material and a polymer; the piezoelectric material is selected from any one of lead zirconate titanate piezoelectric ceramics, barium titanate piezoelectric ceramics, lithium niobate piezoelectric ceramics, polyvinylidene fluoride and its copolymers, and lead magnesium niobate-lead titanate piezoelectric ceramics.

[0044] Further, a signal electrode and a ground electrode are provided on the piezoelectric material layer, and the signal electrode and the ground electrode are respectively disposed on the upper / lower surface or the lower / upper surface of the piezoelectric material layer; the signal electrode and the ground electrode are respectively electrically connected to the corresponding electrodes on the first flexible printed circuit board layer.

[0045] Further, the signal electrode and the ground electrode are Cr / Au electrodes; the Cr / Au electrode includes a Cr layer connected to the piezoelectric material layer and an Au layer provided on the Cr layer; in the technical solution of the present invention, the Cr layer is used to improve the adhesion of the Au layer; the Au layer provides conductivity.

[0046] And / or, the first matching layer is an epoxy resin doped with alumina; the second matching layer is an epoxy resin; the types of epoxy resins of the first matching layer and the second matching layer are the same.

[0047] Further, in the first matching layer, the mass fraction of alumina is 30% - 70%; the particle size of the alumina is 10 - 50 microns.

[0048] And / or, the flexible backing layer is polydimethylsiloxane (PDMS) doped with alumina and hollow glass microspheres.

[0049] Further, in the flexible backing layer, the mass fraction of the alumina is 10% - 40%; the particle size of the alumina is 0.5 - 1 micron; the mass fraction of the hollow glass microspheres is 10% - 40%; the particle size of the hollow glass microspheres is 1 - 5 microns.

[0050] Further, the preparation method of the flexible ultrasonic transducer includes the following steps: (1) Cut the piezoelectric material into a piezoelectric unit array by a cutting method, and fill the gaps of the piezoelectric unit array with epoxy resin; prepare a signal electrode or a ground electrode on the filled upper surface, and sequentially prepare a first matching layer and a second matching layer on the signal electrode or the ground electrode; cut a groove on the filled lower surface to re-form a piezoelectric unit array, fill the groove with polydimethylsiloxane, and prepare a ground electrode or a signal electrode on the filled surface to obtain a flexible acoustic stack layer having a plurality of acoustic stack units; (2) Bond the surface of the flexible acoustic stack layer away from the second matching layer to the first flexible printed circuit board layer by curing epoxy resin; electrically connect the signal electrode and the ground electrode to the corresponding electrodes on the first flexible printed circuit board layer; (3) Prepare a flexible backing layer on the other side of the first flexible printed circuit board layer.

[0051] In some specific embodiments, in step (1), the piezoelectric unit array formed by the second cutting corresponds in size to the piezoelectric unit array formed by the first cutting.

[0052] In some specific embodiments, in step (1), the viscosity of the epoxy resin is 50 - 500 mPa·s; if the viscosity is too high, the fluidity of the epoxy resin is poor, making it difficult to smoothly penetrate into the cutting grooves of the piezoelectric unit array, resulting in insufficient filling and affecting the encapsulation effect and performance.

[0053] In some specific embodiments, in step (1), the epoxy resin used to fill the gaps of the piezoelectric unit array is of the same type as the epoxy resin used to prepare the first matching layer or the second matching layer.

[0054] In some specific embodiments, after filling with polydimethylsiloxane and / or filling with the first epoxy resin, a polishing operation is further included.

[0055] Further, the flexible stretchable electrode includes a flexible stretchable substrate and a conductive layer provided on the flexible stretchable substrate.

[0056] In some specific embodiments, the thickness of the flexible stretchable substrate is 0.5 - 2 mm; the thickness of the conductive layer is 0.3 - 0.5 microns.

[0057] Further, the flexible stretchable substrate is selected from any one of silica gel, styrene - ethylene - butadiene - styrene block copolymer (SEBS), and polydimethylsiloxane.

[0058] And / or, the conductive layer is selected from any one of gold, silver, and platinum; the conductive layer is a patterned conductive layer.

[0059] Further, the conductive layer of the flexible stretchable electrode is electrically connected to the second flexible printed circuit board layer through liquid metal.

[0060] Further, the area on the first flexible printed circuit board layer where the flexible acoustic stack layer is not provided is adhesively connected to the flexible stretchable substrate of the flexible stretchable electrode through double - sided tape.

[0061] Further, the flexible stretchable substrate is subjected to plasma treatment before being adhesively attached with double - sided tape.

[0062] In the technical solution of the present invention, the flexible acoustic stack layer of the flexible ultrasonic transducer is attached to the flexible stretchable substrate, and the integration of the ultrasonic transducer and the flexible stretchable electrode is realized by pasting the area on the first flexible printed circuit board layer where the flexible acoustic stack layer is not provided to the flexible stretchable substrate.

[0063] Example 1 This example provides a flexible wearable patch, and its preparation process is as follows: 1. Prepare an ultrasonic transducer (1) Use a high-precision cutting device to mechanically cut a lead zirconate titanate piezoelectric ceramic sheet with a thickness of 0.3 mm into multiple piezoelectric ceramic units to form a piezoelectric unit array; the cutting is performed along the direction perpendicular to the thickness of the lead zirconate titanate piezoelectric ceramic sheet, cutting once every 300 µm, and the gap formed each time is 100 µm; fill the gaps of the formed piezoelectric unit array with epoxy resin (Epo-Tek 301); after polishing to 250 μm, sputter the first Cr / Au electrode (sputter the Cr layer first, and then the Au layer) on the upper surface; on the first Cr / Au electrode, sequentially stack epoxy resin (Epo-Tek 301) doped with alumina (particle size of 0.5 µm, mass fraction of 30%) as the first matching layer, and pure epoxy resin (Epo-Tek 301) as the second matching layer; (2) Re-form the piezoelectric unit array by cutting grooves on the filled lower surface, fill the grooves with PDMS (Sylgard184), and the piezoelectric unit array corresponds to the gaps of the piezoelectric unit array formed by cutting in step (1); after re-polishing to 250 μm, sputter the second Cr / Au electrode (sputter the Cr layer first, and then the Au layer); the first Cr / Au electrode and the second Cr / Au electrode are used as the signal electrode and the ground electrode respectively, and the signal electrode and the ground electrode are separated by isolation cutting to obtain a flexible acoustic stack layer with multiple acoustic stack units; in this example, the piezoelectric material layer obtained by the above cutting method is a 2-2 type piezoelectric composite material; (3) Electrically connect the second Cr / Au electrode and the first Cr / Au electrode to the corresponding electrodes on the first flexible printed circuit board layer (made of polyimide copper clad laminate); coat epoxy resin (Epo-Tek 301) on the second Cr / Au electrode, bond it to the first flexible printed circuit board layer, and cure at room temperature for 24 hours, and then continue to cure at 45°C for 12 hours to form a firm and reliable bond; (4) Cast PDMS (flexible backsheet layer with a thickness of 2.07 mm) doped with alumina powder (particle size of 0.5 μm, mass fraction of 30%) and hollow glass microspheres (particle size of 1 µm, mass fraction of 30%) on the other side of the first flexible printed circuit board layer, and finally form a flexible ultrasonic transducer with a total thickness of 430 μm.

[0064] The flexible ultrasonic transducer prepared in this embodiment has good flexibility, durability and stability.

[0065] 2. Preparation of flexible stretchable electrodes In this embodiment, a 2-mm-thick silicone film (Ecoflex 00-20, with a mixing mass ratio of A:B of 1:1) is used as the flexible stretchable substrate; the silicone liquid is spin-coated three times (200 rpm, 1 min) and cured at room temperature for 1 hour to obtain a film; a 400-nm-thick patterned gold layer is deposited on the silicone film to prepare an electrode channel; The liquid metal (gallium-indium alloy, with gallium and indium contents of 75% and 25% respectively, and a melting point of 16°C) is coated on the tail of the electrode channel by mask roll coating; the pins of the second flexible printed circuit board layer (not shown in the figure) are connected to the liquid metal at the tail of the electrode channel and fixed with an adhesive (DOWSIL 734); finally, a silicone film (Ecoflex 00-20) is spin-coated for encapsulation at 1500 rpm for 1 min.

[0066] 3. Preparation of flexible wearable patches Integrate the flexible stretchable electrode and the flexible ultrasonic transducer: perform plasma treatment on the side of the flexible stretchable electrode without the patterned gold layer to enhance the surface energy, improve the bonding strength and stability; Stick double-sided tape on the area of the first flexible printed circuit board layer without the flexible acoustic stack layer, and then bond the side of the flexible stretchable electrode that has been plasma-treated to the double-sided tape to complete the integration of the flexible ultrasonic transducer and the flexible stretchable electrode, thereby preparing a flexible wearable patch.

[0067] In order to make the patch provided in this embodiment firmly adhere to the skin, its surface is treated with an adhesive, and the specific steps are as follows: perform plasma treatment on the surface of the flexible stretchable electrode in the flexible wearable patch, spin-coat a pressure-sensitive adhesive, and cure it at 60°C for 2 hours.

[0068] Figure 3Pictures of a traditional commercial ultrasound probe (Siemens Acuson L10-5 Ultrasound Transducer with a central frequency of 7.5 MHz) and a flexible ultrasound probe prepared with the flexible wearable patch in this embodiment for muscle structure imaging. It can be seen from the figures that: (1) The commercial ultrasound probe cannot truly reflect the muscle structure: The commercial probe needs to apply pressure and use an ultrasound coupling agent to eliminate the air gap. In the case of no pressure applied, the muscle structure in the ultrasound image is blurred and difficult to identify. After applying pressure, clear muscle imaging can be obtained, but at the same time, obvious mechanical deformation occurs in the skin and superficial muscles, resulting in a reduction of about 21.1% in tissue thickness. This phenomenon may affect the consistency between the imaging result and the actual muscle structure, thereby reducing the diagnostic accuracy. (2) The flexible wearable patch in this embodiment can be used for muscle structure imaging without applying pressure. It has a good conformal attachment effect with the skin, and the muscle thickness that can be collected is significantly greater than that which can be collected by the commercial probe.

[0069] Figure 4 It is a muscle compression rate graph caused by a traditional commercial ultrasound probe and a flexible ultrasound probe prepared with the flexible wearable patch in this embodiment for muscle structure imaging. The commercial ultrasound probe causes 21.1% tissue deformation during the compression imaging process, while the flexible ultrasound probe only causes 1.4% tissue deformation when directly attached for imaging.

[0070] Figure 5 It is the ultrasound imaging of the brachioradialis muscle in the forearm, erector spinae muscle in the back, and sternocleidomastoid muscle in the neck by the flexible ultrasound probe prepared with the flexible wearable patch in this embodiment under deformations of 7.2%, 26.8%, and 37.5%.

[0071] Figure 6a and Figure 6b are respectively the adhesion state photos of the flexible ultrasound probes prepared with the flexible wearable patch with and without a flexible stretchable electrode on the neck skin after multiple right-handed rotations, for evaluating their imaging effects under static and dynamic conditions. The test process is as follows: A flexible ultrasonic probe prepared from a flexible wearable patch without a flexible stretchable electrode was attached to the surface of the subject's neck skin, and an ultrasonic coupling agent was used to eliminate the air gap. In the static state, the ultrasonic probe could achieve clear muscle imaging, and no tissue deformation caused by the probe pressure was observed, verifying that it could perform high-quality imaging without external pressure and had good adhesion and comfort. However, in the dynamic test, when the subject rotated the neck, as the strain on the skin surface increased, the ultrasonic probe gradually detached from the skin. When the rotation reached the 6th time, the ultrasonic probe completely separated from the skin, resulting in the failure of ultrasonic imaging. This indicates that in the dynamic situation of large skin deformation, a simple flexible ultrasonic transducer is difficult to maintain close contact with the skin and cannot achieve continuous and stable imaging ( Figure 6a ).

[0072] In this embodiment, a flexible ultrasonic probe prepared from a flexible wearable patch with a flexible stretchable electrode was attached to the surface of the human neck skin, and an ultrasonic coupling agent was used to eliminate the air gap. In the static state, the ultrasonic probe achieved high-quality muscle imaging, and no tissue deformation caused by the probe pressure was observed, showing good adhesion and comfort. In the dynamic test, when the subject rotated the neck, as the strain on the skin surface increased, the ultrasonic probe could still closely adhere to the skin and maintain stable imaging performance. Further tests showed that even after 150 consecutive neck rotations, high-quality ultrasonic imaging could still be achieved, and there was no phenomenon of detachment from the skin or blurred imaging, demonstrating its long-term stability under large-deformation dynamic conditions. This is mainly due to the fact that the flexible stretchable electrode effectively releases stress during skin deformation, significantly improving the adhesion between the ultrasonic probe and the skin, preventing the probe from detaching due to skin strain, and thus ensuring the continuity and accuracy of imaging ( Figure 6b ).

[0073] Figure 7 This is the analysis of the ultrasonic structure and electromyogram (EMG) functional signals of the flexible ultrasonic probe (WSFP) prepared from the flexible wearable patch in this embodiment for the bimodal synchronous monitoring of the brachioradialis muscle in the forearm: Figure 7 Figure a in it is a photo of the WSFP attached to the brachioradialis muscle in the forearm for structure-function monitoring; Figure 7 Figure b in it is the ultrasonic imaging (i) and EMG distribution (ii) of the brachioradialis muscle obtained synchronously during relaxation and fist clenching; Figure 7 Figure c in it is the relative relationship between the muscle structure characteristics (area, minimum and maximum thickness) and EMG (RMS, root mean square value) during synchronous monitoring; Figure 7 Figure d in it is the action recognition accuracy of the unimodal signal and the bimodal synchronous monitoring signal. It can be seen from the figure that the action recognition accuracy of the bimodal data is significantly higher than that of the unimodal data.

[0074] Figure 8 The flexible ultrasonic probe prepared using the flexible wearable patch in this embodiment is used to perform synchronous structure-function monitoring on children with Charcot-Marie-Tooth (CMT) disease. This is a specific case of synchronous ultrasonic imaging and electromyogram monitoring of children with CMT using the flexible ultrasonic probe (from top to bottom are left turn, right turn, left flexion, and right flexion movements, and the dashed area indicates the detected sternocleidomastoid muscle (SCM) structure). As can be seen from the figure, compared with the healthy side, the ultrasonic imaging of the affected side shows severe muscle bending, blurred edges, muscle fibrosis, and increased muscle thickness. The topographic map based on the electromyogram signal shows the asymmetry between the two sides of CMT patients during the movement task.

[0075] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A flexible wearable patch, characterized in that, It includes a flexible ultrasonic transducer and a flexible stretchable electrode adhesively connected thereto; The flexible ultrasonic transducer includes a flexible backing layer, a first flexible printed circuit board layer arranged in a stacked manner in sequence, and a flexible acoustic stack layer arranged on the first flexible printed circuit board layer; the area on the first flexible printed circuit board layer where the flexible acoustic stack layer is not arranged is adhesively connected to the flexible stretchable electrode; The flexible wearable patch further includes a second flexible printed circuit board layer; the flexible stretchable electrode is electrically connected to the second flexible printed circuit board layer.

2. The flexible wearable patch according to claim 1, characterized in that, The flexible acoustic stack layer includes a plurality of acoustic stack units; the flexible acoustic stack layer includes a piezoelectric material layer, a first matching layer, and a second matching layer arranged in a stacked manner in sequence; wherein, the second matching layer faces the flexible stretchable electrode.

3. The flexible wearable patch according to claim 2, characterized in that, A signal electrode and a ground electrode are arranged on the piezoelectric material layer, and the signal electrode and the ground electrode are respectively arranged on the upper / lower surface or lower / upper surface of the piezoelectric material layer; the signal electrode and the ground electrode are respectively electrically connected to the corresponding electrodes on the first flexible printed circuit board layer.

4. The flexible wearable patch according to claim 3, wherein The signal electrode and the ground electrode are Cr / Au electrodes; the Cr / Au electrode includes a Cr layer connected to the piezoelectric material layer and an Au layer arranged on the Cr layer; And / or, the first matching layer is an epoxy resin doped with alumina; the second matching layer is an epoxy resin; the types of the epoxy resins of the first matching layer and the second matching layer are the same; And / or, the flexible backing layer is a polydimethylsiloxane doped with alumina and hollow glass microspheres.

5. The flexible wearable patch according to claim 3 or 4, wherein The preparation method of the flexible ultrasonic transducer includes the following steps: (1) Cut the piezoelectric material into a piezoelectric unit array by a cutting method, and fill the gaps of the piezoelectric unit array with epoxy resin; prepare a signal electrode or a ground electrode on the filled upper surface, and sequentially prepare a first matching layer and a second matching layer on the signal electrode or the ground electrode; cut a groove on the filled lower surface to reform the piezoelectric unit array, fill the groove with polydimethylsiloxane, and prepare a ground electrode or a signal electrode on the filled surface to obtain a flexible acoustic stack layer with a plurality of acoustic stack units; (2) Curing and bonding the surface of the flexible acoustic stack layer away from the second matching layer to the first flexible printed circuit board layer with epoxy resin; electrically connecting the signal electrode and the ground electrode to the corresponding electrodes on the first flexible printed circuit board layer; (3) Prepare a flexible backing layer on the other side of the first flexible printed circuit board layer.

6. The flexible wearable patch according to claim 1, wherein, The flexible stretchable electrode includes a flexible stretchable substrate and a conductive layer arranged on the flexible stretchable substrate.

7. The flexible wearable patch according to claim 6, wherein The flexible stretchable substrate is selected from any one of silica gel, styrene-ethylene-butadiene-styrene block copolymer, and polydimethylsiloxane; And / or, the conductive layer is selected from any one of gold, silver, and platinum; the conductive layer is a patterned conductive layer.

8. The flexible wearable patch according to claim 6, wherein The conductive layer of the flexible stretchable electrode is electrically connected to the second flexible printed circuit board layer through liquid metal.

9. The flexible wearable patch according to claim 6, wherein The area on the first flexible printed circuit board layer where the flexible acoustic stack layer is not arranged is adhesively connected to the flexible stretchable substrate of the flexible stretchable electrode through double-sided tape.

10. The flexible wearable patch according to claim 8, characterized in that, Before being pasted with double-sided tape, the flexible and stretchable substrate also undergoes plasma treatment.

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