Ultrasound-driven electrical stimulation device and effect evaluation method

Abstract

The invention provides an ultrasonic drive electrical stimulation device and an effect evaluation method, which can be applied to the technical field of medical equipment and physiological signal detection. The device comprises an ultrasonic array, a piezoelectric plate and a processor, wherein the processor is electrically connected with the ultrasonic array, the piezoelectric plate is located in a target area of a target object, the ultrasonic array comprises a plurality of ultrasonic array elements, and the processor is configured to control the plurality of ultrasonic array elements in the ultrasonic array to emit first ultrasonic waves according to a first frequency, the first ultrasonic wave of the first frequency enables the piezoelectric plate to generate electrical stimulation to act on a target area.

Description

Technical Field

[0001] The present disclosure relates to the technical fields of medical devices and physiological signal detection technologies, and more particularly, to an ultrasound-driven electrical stimulation device and a method for effect evaluation. Background Art

[0002] Electrical stimulation is a technology that uses an electric current to act on biological tissues and causes behavioral, physiological, or functional changes by simulating or regulating neural electrical activities. Therefore, electrical stimulation can be used to treat and repair damaged parts in biological tissues. For example, electrical stimulation can be applied in wound healing, cardiac tissue repair, tissue reconstruction of muscles and tendons, treatment of abnormalities and injuries in organs such as the bladder and endometrium. However, the flexibility of electrical stimulation devices in related technologies is poor, and the penetrability of electrical stimulation is also poor. Summary of the Invention

[0003] In view of this, the present disclosure provides an ultrasound-driven electrical stimulation device and a method for effect evaluation.

[0004] One aspect of the present disclosure provides an ultrasound-driven electrical stimulation device, including an ultrasound array, a piezoelectric sheet, and a processor;

[0005] Wherein, the processor is electrically connected to the ultrasound array, the piezoelectric sheet is located in a target area of a target object, the ultrasound array includes a plurality of ultrasound elements, and the processor is configured to control each of the plurality of ultrasound elements in the ultrasound array to emit first ultrasonic waves at a first frequency, and the first ultrasonic waves at the first frequency cause the piezoelectric sheet to generate an electrical stimulation acting on the target area.

[0006] According to an embodiment of the present disclosure, the ultrasound array further includes a first flexible encapsulation layer and a second flexible encapsulation layer, the ultrasound elements are disposed between the first flexible encapsulation layer and the second flexible encapsulation layer, a first flexible metal electrode corresponding to the ultrasound element is disposed on a surface of the first flexible encapsulation layer adjacent to the ultrasound element, and a second flexible metal electrode corresponding to the ultrasound element is disposed on a surface of the second flexible encapsulation layer adjacent to the ultrasound element.

[0007] According to an embodiment of the present disclosure, the material of the piezoelectric sheet includes a material that can be degraded;

[0008] The piezoelectric sheet includes a piezoelectric thin film, nanowires disposed on the piezoelectric thin film, and a coating layer disposed on the piezoelectric thin film and the nanowires.

[0009] According to an embodiment of the present disclosure, the material of the piezoelectric sheet includes one of poly-L-lactic acid and poly-L-lactic acid.

[0010] According to an embodiment of the present disclosure, the above-mentioned first frequency is determined according to the distance between the piezoelectric sheet and the ultrasonic array and the elastic stress of the piezoelectric sheet;

[0011] The above-mentioned first frequency is determined by the following operations:

[0012] According to the distance between the piezoelectric sheet and the ultrasonic array and the attenuation index of the above-mentioned first ultrasonic wave in the target object, determine the attenuation amount of the above-mentioned first ultrasonic wave;

[0013] According to the attenuation amount of the above-mentioned first ultrasonic wave, determine the compensation frequency of the above-mentioned ultrasonic element;

[0014] According to the elastic stress, area, density and vibration mode of the piezoelectric sheet, determine the resonance frequency of the piezoelectric sheet;

[0015] According to the compensation frequency of the above-mentioned ultrasonic element and the resonance frequency of the piezoelectric sheet, determine the above-mentioned first frequency of each of the plurality of above-mentioned ultrasonic elements.

[0016] According to an embodiment of the present disclosure, the above-mentioned processor is configured to make the first ultrasonic waves emitted by each of the plurality of above-mentioned ultrasonic elements uniformly distributed on the surface of the piezoelectric sheet by adjusting the phases of the first ultrasonic waves emitted by each of the plurality of above-mentioned ultrasonic elements, so that the piezoelectric sheet generates an electrical stimulation acting on the target area; or

[0017] The above-mentioned processor is configured to make the first ultrasonic waves emitted by each of the plurality of above-mentioned ultrasonic elements focus on a target point on the surface of the piezoelectric sheet by adjusting the phases of the first ultrasonic waves emitted by each of the plurality of above-mentioned ultrasonic elements, so that the piezoelectric sheet generates an electrical stimulation acting on the target area.

[0018] According to an embodiment of the present disclosure, the above-mentioned processor is further configured to control each of the plurality of above-mentioned ultrasonic elements to emit a second ultrasonic wave according to a second frequency, so that the second ultrasonic wave drives the target area to vibrate, control the ultrasonic array to emit a plane detection wave, obtain an echo signal of the piezoelectric sheet based on the plane detection wave, generate a stress change image of the piezoelectric sheet according to the echo signal, and determine an evaluation result about the target area by the above-mentioned processor according to the stress change image of the piezoelectric sheet.

[0019] Another aspect of the present disclosure provides a method for effect evaluation using the device as described above, wherein the above-mentioned device includes an ultrasonic array, a piezoelectric sheet and a processor, the above-mentioned processor is electrically connected to the above-mentioned ultrasonic array, the above-mentioned ultrasonic array includes a plurality of ultrasonic elements, and the method includes:

[0020] The above-mentioned processor controls the plurality of the above-mentioned ultrasonic array elements to each emit second ultrasonic waves at a second frequency, so that the second ultrasonic waves drive the target area to generate vibrations, wherein the piezoelectric sheet is conformal to the target area of the target object;

[0021] The above-mentioned processor controls the above-mentioned ultrasonic array to emit a planar detection wave, so as to obtain an echo signal of the above-mentioned piezoelectric sheet based on the planar detection wave;

[0022] The above-mentioned processor generates a stress change image of the above-mentioned piezoelectric sheet according to the above-mentioned echo signal, wherein the stress change image characterizes the elastic state of the above-mentioned target area adjacent to the above-mentioned piezoelectric sheet;

[0023] The above-mentioned processor determines an evaluation result regarding the above-mentioned target area according to the stress change image of the above-mentioned piezoelectric sheet.

[0024] According to an embodiment of the present disclosure, among the plurality of the above-mentioned ultrasonic array elements, a first ultrasonic array element and a second ultrasonic array element are included, and the above-mentioned controlling, by the above-mentioned processor, the plurality of the above-mentioned ultrasonic array elements to each emit second ultrasonic waves at a second frequency includes:

[0025] The above-mentioned processor controls the above-mentioned first ultrasonic array element to emit a first sub-ultrasonic wave at a first phase of the above-mentioned second frequency;

[0026] The above-mentioned processor controls the above-mentioned second ultrasonic array element to emit a second sub-ultrasonic wave at a second phase of the above-mentioned second frequency, so that the first sub-ultrasonic wave and the second sub-ultrasonic wave are focused in the above-mentioned target area and generate an acoustic radiation force to drive the above-mentioned target area to generate vibrations.

[0027] According to an embodiment of the present disclosure, the above-mentioned generating, by the above-mentioned processor, the stress change image of the above-mentioned piezoelectric sheet according to the above-mentioned echo signal includes:

[0028] The above-mentioned processor determines the acoustic emission amplitudes at different positions of the above-mentioned piezoelectric sheet according to the above-mentioned echo signal;

[0029] A stress change image of the above-mentioned piezoelectric sheet is generated according to the acoustic emission amplitudes at different positions of the above-mentioned piezoelectric sheet.

[0030] According to an embodiment of the present disclosure, by controlling the respective first frequencies of a plurality of ultrasonic array elements in an ultrasonic array through a processor, an electric stimulation can be generated by a piezoelectric sheet and applied to a target area. The ultrasonic drive electric stimulation device according to the embodiment of the present disclosure combines the characteristics of strong penetration of the ultrasonic array and the characteristics that the piezoelectric sheet can generate an electric signal more beneficial to nerves, enabling the piezoelectric sheet disposed in the target area to directly perform electric stimulation on the target area. By selecting different first frequencies, different degrees of electric stimulation can be generated, increasing the flexibility of the electric stimulation. Moreover, the ultrasonic array can continuously emit the first ultrasonic wave, enabling the piezoelectric sheet to continuously generate electric stimulation and increasing the working time of the piezoelectric sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, the above and other objects, features, and advantages of the present disclosure will become clearer. In the drawings:

[0032] Figure 1 Schematically shows a block diagram of an ultrasonic drive electric stimulation device according to an embodiment of the present disclosure;

[0033] Figure 2 Schematically shows a formation schematic diagram of an ultrasonic array according to an embodiment of the present disclosure;

[0034] Figure 3 Schematically shows a formation schematic diagram of a piezoelectric sheet according to an embodiment of the present disclosure;

[0035] Figure 4 Schematically shows a regulation schematic diagram of an ultrasonic array according to an embodiment of the present disclosure;

[0036] Figure 5 Schematically shows a flowchart of a method for effect evaluation using an ultrasonic drive electric stimulation device according to an embodiment of the present disclosure;

[0037] Figure 6 Schematically shows a principle schematic diagram of a method for effect evaluation using an ultrasonic drive electric stimulation device according to an embodiment of the present disclosure; and

[0038] Figure 7 Schematically shows a system for ultrasonic drive electric stimulation and effect evaluation according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the following detailed description, for the sake of explanation, numerous specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, evidently, one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts of the present disclosure.

[0040] The terms used herein are merely for describing specific embodiments and are not intended to limit the present disclosure. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0041] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0042] In the case of using expressions such as "at least one of A, B, and C, etc.", generally, it should be interpreted according to the meaning commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include, but is not limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0043] In the embodiments of the present disclosure, in terms of the collection, update, analysis, processing, use, transmission, provision, disclosure, storage, etc. of the data involved (for example, including but not limited to user personal information), they all comply with the provisions of relevant laws and regulations, are used for legal purposes, and do not violate public order and good customs. In particular, necessary measures are taken for user personal information to prevent illegal access to user personal information data and to safeguard user personal information security and network security.

[0044] In the embodiments of the present disclosure, the authorization or consent of the user is obtained before obtaining or collecting user personal information.

[0045] In one example, a portable four-in-one knee treatment device and method are provided for massaging and electrostimulating the knee that extends into the interior of the treatment device main body; in another example, a photoelectric combined nerve regulation sleep promotion device is provided that can perform electrostimulation on the user's ear and perform light stimulation on the user's eye to promote sleep. However, neither of them can obtain the stimulation treatment effect in real time, resulting in inaccurate stimulation.

[0046] Although ultrasound stimulation can solve the problem of poor penetration of electrical stimulation, it is necessary to directly contact the nerve site with an electrode, and non-contact deep stimulation cannot be performed. When using a single electrode for stimulation, it is necessary to manually change the target point, resulting in poor flexibility. When using an electrode array for stimulation, there are problems such as poor penetration of the surface electrode array, large trauma of the implanted electrode array, poor spatial directivity, and low resolution. In one example, a method for automatic positioning and mapping of deep nerves by ultrasound is provided, which can relatively well solve the above problems. However, using this method for ultrasound stimulation is a stimulation method based on the principle of mechanical vibration. Since nerves transmit various signals based on electrical signals, the effect of ultrasound stimulation is worse than that of electrical stimulation, and there is also a problem that the stimulation effect cannot be detected in real time.

[0047] In view of this, an embodiment of the present disclosure provides an ultrasound-driven electrical stimulation device, including an ultrasound array, a piezoelectric sheet, and a processor. Wherein, the processor is electrically connected to the ultrasound array, the piezoelectric sheet is located in the target area of the target object, the ultrasound array includes a plurality of ultrasound elements, and the processor is configured to control each of the plurality of ultrasound elements in the ultrasound array to emit first ultrasonic waves at a first frequency, and the first ultrasonic waves at the first frequency cause the piezoelectric sheet to generate an electrical stimulation acting on the target area.

[0048] Figure 1 A block diagram of an ultrasound-driven electrical stimulation device according to an embodiment of the present disclosure is schematically shown.

[0049] As Figure 1 shown, the ultrasound-driven electrical stimulation device 100 includes an ultrasound array 110, a piezoelectric sheet 120, and a processor 130.

[0050] Wherein, the processor 130 is electrically connected to the ultrasound array 110, the piezoelectric sheet 120 is located in the target area of the target object, the ultrasound array 110 includes a plurality of ultrasound elements, and the processor 130 is configured to control each of the plurality of ultrasound elements in the ultrasound array 110 to emit first ultrasonic waves at a first frequency, and the first ultrasonic waves at the first frequency cause the piezoelectric sheet 120 to generate an electrical stimulation acting on the target area.

[0051] According to an embodiment of the present disclosure, the target area of the target object may be biological tissue that needs to be electrically stimulated, such as biological tissues such as wounds, heart tissues, muscles, tendons, bladders, uteruses, and kidneys.

[0052] According to an embodiment of the present disclosure, the first frequencies of multiple ultrasonic array elements may be the same or different. It can be set according to the range and magnitude of the electrical stimulation required to be generated by the piezoelectric sheet. For example, in the case where electrical stimulation is required at a certain point in the piezoelectric sheet, the first frequencies of the multiple ultrasonic array elements can be set to be the same. Ultrasonic waves with the same frequency are more likely to be focused, and the energy at the focal point is relatively stable. While in the case where uniform electrical stimulation is required for the entire piezoelectric sheet, the first frequencies of the multiple ultrasonic array elements can be set to be the same or different, so that the first ultrasonic waves emitted by the multiple ultrasonic array elements at the first frequencies can uniformly act on the piezoelectric sheet to cause the entire piezoelectric sheet to generate uniform electrical stimulation.

[0053] According to an embodiment of the present disclosure, by controlling the first frequencies of multiple ultrasonic array elements in the ultrasonic array through a processor, the piezoelectric sheet can generate electrical stimulation acting on the target area. The ultrasonic-driven electrical stimulation device according to the embodiment of the present disclosure combines the characteristics of strong penetration of the ultrasonic array and the characteristics that the piezoelectric sheet can generate electrical signals more beneficial to nerves, enabling the piezoelectric sheet arranged in the target area to directly perform electrical stimulation on the target area. By selecting different first frequencies, different degrees of electrical stimulation can be generated, increasing the flexibility of electrical stimulation. Moreover, the ultrasonic array can continuously emit the first ultrasonic waves, so that the piezoelectric sheet can continuously generate electrical stimulation, increasing the working time of the piezoelectric sheet.

[0054] Figure 2 Schematically shows a formation schematic diagram of an ultrasonic array according to an embodiment of the present disclosure.

[0055] As Figure 2 shown, the ultrasonic array 110 further includes a first flexible encapsulation layer 210 and a second flexible encapsulation layer 220. Ultrasonic array elements 230 are arranged between the first flexible encapsulation layer 210 and the second flexible encapsulation layer 220. A first flexible metal electrode 240 corresponding to the ultrasonic array elements 230 is arranged on the surface of the first flexible encapsulation layer 210 adjacent to the ultrasonic array elements 230, and a second flexible metal electrode 250 corresponding to the ultrasonic array elements 230 is arranged on the surface of the second flexible encapsulation layer 220 adjacent to the ultrasonic array elements 230.

[0056] According to an embodiment of the present disclosure, an ultrasonic array element may include a plurality of materials with central frequencies ranging from 1 MHz to 30 MHz, which are used for ultrasonic transmission and reception. Among them, the ultrasonic array element 230 may select a ytterbium (Yb) / bismuth (Bi) double-doped lead magnesium niobate-lead titanate (PMN-PT) single crystal as the piezoelectric material of the ultrasonic array element, or other piezoelectric materials with a relatively large piezoelectric coefficient; the first flexible encapsulation layer 210 and the second flexible encapsulation layer 220 may adopt flexible materials to enhance the van der Waals force and improve the adhesion between the flexible encapsulation layer and the skin. For example, it may be polydimethylsiloxane (PDMS); the first flexible metal electrode 240 and the second flexible metal electrode 250 may adopt metal materials with high ductility. For example, it may be copper material. First, the first flexible encapsulation layer 210 and the first flexible metal electrode 240 may form a back protection layer of the ultrasonic array, and the second flexible encapsulation layer 220 and the second flexible metal electrode 250 may form a matching layer of the ultrasonic array. The ultrasonic array element 230 may be placed between the first flexible encapsulation layer 210 and the second flexible encapsulation layer 220 and correspond to the first flexible metal electrode 240 and the second flexible metal electrode 250 for welding. Finally, the PDMS material may be used for fixture potting to form a flexible ultrasonic array 110.

[0057] Figure 3 Schematically shows a formation schematic diagram of a piezoelectric sheet according to an embodiment of the present disclosure.

[0058] As Figure 3 shown, the piezoelectric sheet 120 includes a piezoelectric thin film 310, nanowires 320 disposed on the piezoelectric thin film, and a coating layer 330 disposed on the piezoelectric thin film 310 and the nanowires 320.

[0059] According to an embodiment of the present disclosure, the piezoelectric sheet needs to be placed in a target area. Therefore, the material of the piezoelectric sheet may include materials that can be degraded. For example, the material of the piezoelectric sheet may include one of poly-L-lactic acid (PLLA) and polylactic acid (PLA), or other degradable materials may also be selected. The piezoelectric thin film 310 may be formed by electrospinning technology and 3D printing technology using, for example, PLA material in a high-pressure environment. Potassium sodium niobate (KNN) nanowires may be formed on the piezoelectric thin film 310 by a solid-phase reaction method. A coating layer 330 may be formed on the piezoelectric thin film 310 and the nanowires 320. The material of the coating layer 330 may be a polydopamine (PDA) material with biocompatibility and biodegradability. Since the material of the piezoelectric sheet is flexible, it can fit well with the target area.

[0060] According to an embodiment of the present disclosure, the biodegradable piezoelectric sheet material enables the piezoelectric sheet to be implanted only once without the need for a second operation, reducing the harm to the target object. Moreover, the materials of the piezoelectric sheet are all biodegradable and will not cause harm to the target object.

[0061] Due to the complex surface shape of the skin and the non-planar shape of the target area such as organs or tissues, when the ultrasonic array drives the piezoelectric sheet for electrical stimulation, it is necessary to solve the problem of uneven charge release intensity of the piezoelectric sheet. The reasons for the uneven charge release intensity of the piezoelectric sheet are as follows: The maximum sound pressure point of ultrasonic focusing is not on the piezoelectric sheet, resulting in the piezoelectric sheet not resonating at the optimal point; the shift of the intrinsic resonance frequency of the piezoelectric sheet leads to the attenuation of the resonant state of the piezoelectric sheet. Therefore, measures need to be taken from two aspects to improve the charge release efficiency of the piezoelectric sheet: compensating for the change in ultrasonic sound pressure caused by the change in the distance between the ultrasonic array and the piezoelectric sheet attached to the target area; compensating for the change in the intrinsic resonance frequency point of the piezoelectric sheet due to its commonality with the target area and thus the change caused by the additional strain. To achieve efficient charge release of the conformal piezoelectric sheet, the present disclosure adopts a method of regulating different ultrasonic frequencies in the ultrasonic array elements to drive the piezoelectric sheet according to the elastic stress distribution. of the change; compensating for the change in the intrinsic resonance frequency point of the piezoelectric sheet due to its commonality with the target area and thus the change caused by the additional strain. To achieve efficient charge release of the conformal piezoelectric sheet, the present disclosure adopts a method of regulating different ultrasonic frequencies in the ultrasonic array elements to drive the piezoelectric sheet according to the elastic stress distribution. With the change of the additional strain. To achieve efficient charge release of the conformal piezoelectric sheet, the present disclosure adopts a method of regulating different ultrasonic frequencies in the ultrasonic array elements to drive the piezoelectric sheet according to the elastic stress distribution.

[0062] According to an embodiment of the present disclosure, after the piezoelectric material of the ultrasonic array element is excited by ultrasonic waves, through thickness ( is the wavelength) of the matching layer, the intensity of the ultrasonic wave reflected back to the flexible encapsulation layer on the back is less than the intensity incident on the skin tissue, that is, I transmission > I reflection. At this time, the ultrasonic wave can reach the theoretical depth well for electrical stimulation. After the ultrasonic wave is incident, the sound pressure of the ultrasonic wave can be expressed by the following formula (1):

[0063] (1)

[0064] Wherein, represents the signal amplitude of the ultrasonic wave, represents the resonant angular frequency of the ultrasonic wave, represents the speed of the ultrasonic wave, represents the density of the piezoelectric sheet.

[0065] It can be seen from formula (1) that after the center frequency of the ultrasonic array is determined, only the parameter will affect the change of the sound pressure. When the ultrasonic wave propagates in the target area, it will also cause attenuation of the amplitude, and the longer the transmission time, the greater the attenuation. Therefore, it is necessary to introduce an attenuation factor into formula (1). The transmission attenuation of the ultrasonic wave can be calculated by the following formula (2):

[0066] (2)

[0067] Wherein, Indicates the transmission distance of the ultrasonic wave, Indicates the attenuation index of the ultrasonic wave in the target area.

[0068] It can be seen from formula (2) that when the attenuation index is fixed, the change in distance will cause a change in the amplitude of the ultrasonic wave. In the attenuation formula is changed to , then the sound pressure will generate a decrease. Therefore, to compensate for the sound pressure loss, compensation can be performed on the frequency of the ultrasonic wave according to formula (1). For the ultrasonic array, the frequency of the ultrasonic array element can be switched and focused on the stimulation site. Therefore, the attenuation amount of the first ultrasonic wave can be determined according to the distance between the piezoelectric sheet and the ultrasonic array and the attenuation index of the first ultrasonic wave in the target object; according to the attenuation amount of the first ultrasonic wave, the compensation frequency of the ultrasonic array element can be determined.

[0069] For the piezoelectric sheet, due to the commonality with the target area, it is necessary to establish the relationship between the intrinsic vibration frequency and the common stress. For the natural resonance frequency of the square piezoelectric film, it can be expressed by the following formula:

[0070] (3)

[0071] Wherein, represents the stress of the piezoelectric sheet, a is the area of the square piezoelectric film, m and n are numbers related to the vibration mode. When n = m = 1, is the intrinsic resonance frequency.

[0072] According to the embodiment of the present disclosure, the resonance frequency of the piezoelectric sheet can be determined according to the elastic stress, area, density and vibration mode of the piezoelectric sheet according to formula (3).

[0073] It can be seen from the foregoing analysis that the first frequency of the first ultrasonic wave emitted is determined according to the distance between the piezoelectric sheet and the ultrasonic array and the elastic stress of the piezoelectric sheet. For an ultrasonic array with a fixed center frequency, the sound field distribution has the strongest main lobe sound pressure. If the intrinsic frequency of the piezoelectric sheet undergoes a relative shift, then the sound pressure of the ultrasonic main lobe needs to change correspondingly in depth. However, according to formula (3), the deeper the piezoelectric sheet bends, the greater the stress, and the greater the stress, the higher the resonance frequency. But for ultrasonic waves, the higher the frequency, the shallower the penetration depth, which is a pair of contradictions. Therefore, a theoretical model of piezoelectric sheet electrostriction between phased ultrasonic regulation and conformal piezoelectric sheet stress change is established by combining formulas (1), (2) and (3) to obtain the distance between the conformal piezoelectric sheet and the ultrasonic array emission source, as well as the elastic stress of the conformal piezoelectric sheet, so as to obtain the basis for phased regulation. By using the phased array focusing method, the first frequency of each of the multiple ultrasonic array elements can be determined according to the compensation frequency of the ultrasonic array element and the resonance frequency of the piezoelectric sheet, and the intensity of the main lobe sound pressure can be changed.

[0074] According to an embodiment of the present disclosure, when transmitting a phased array, it is necessary to set the delay of each ultrasonic element so that the main lobes of the ultrasonic waves of each ultrasonic element can be focused on the measured point, improving the signal sound pressure; when receiving a signal, it is necessary to add a delay to the signal received by each ultrasonic element to perform phase manipulation.

[0075] Figure 4 Schematically shows a regulation schematic diagram of an ultrasonic array according to an embodiment of the present disclosure.

[0076] As Figure 4 shown in a of, the phase of the first ultrasonic waves emitted by each of the plurality of ultrasonic elements can be regulated so that the first ultrasonic waves emitted by each of the plurality of ultrasonic elements are evenly distributed on the surface of the piezoelectric sheet, causing the piezoelectric sheet to generate an electrical stimulation acting on the target area. In Figure 4 a of, the first frequencies of each ultrasonic element can be different, so that the first ultrasonic waves can be evenly distributed on the surface of the piezoelectric sheet

[0077] As Figure 4 shown in b of, the phase of the first ultrasonic waves emitted by each of the plurality of ultrasonic elements can also be regulated so that the first ultrasonic waves emitted by each of the plurality of ultrasonic elements are focused on the target point on the surface of the piezoelectric sheet, causing the piezoelectric sheet to generate an electrical stimulation acting on the target area. In Figure 4 b of, the first frequencies of each ultrasonic element can be the same, so that the first ultrasonic waves can be focused on the target point.

[0078] According to an embodiment of the present disclosure, after electrically stimulating the target area through the ultrasonic array and the piezoelectric sheet, the target area can also be evaluated.

[0079] In the related art, the detection accuracy of elastic modulus by a single ultrasonic source is relatively low. The main reasons are as follows: In the ultrasonic wireless signal detection technology with a single ultrasonic frequency, the most widely used static elastography requires manual pressing to deform the tissue, making it very difficult to control the form, magnitude, and action mode of the applied external force; for the other two types of elastography methods: acoustic radiation force elastography and shear wave elastography, both use acoustic radiation force to excite the tissue to be measured and do not require manual pressing. The focused acoustic radiation force will cause displacement in the focused area, which is related to the elasticity of the tissue, but this displacement is very small and may be affected by various environmental noises such as body, breathing, and cardiovascular movement; due to the complex surface shape of the skin and the non-planar shape of the organs or tissues.

[0080] The excitation source in the acoustic radiation force imaging method is the acoustic radiation force. When a sound wave propagating in a fluid medium is incident on an obstacle, a forward force is generated in the direction of sound wave propagation. This forward time-averaged pressure is usually referred to as the acoustic radiation force. Its direction is the same as the direction of sound propagation. It is composed of second-order small quantities in the mathematical equations describing the propagation law of sound waves in a fluid medium. In order to generate an acoustic radiation force with sufficient intensity, it is necessary to perform ultrasonic focusing inside biological tissues. Therefore, ultrasonic focusing can be performed in the target area by the ultrasonic array provided in the embodiments of the present disclosure, and in-situ evaluation of the target area can be achieved by detecting the stress change of the piezoelectric element. Specifically as follows.

[0081] Figure 5 The flowchart of the method for effect evaluation using an ultrasonic-driven electrical stimulation device according to an embodiment of the present disclosure is schematically shown.

[0082] As Figure 5 shown, the ultrasonic-driven electrical stimulation device includes an ultrasonic array, a piezoelectric element, and a processor. The processor is electrically connected to the ultrasonic array. The ultrasonic array includes a plurality of ultrasonic array elements. The method includes operations S510 to S540.

[0083] In operation S510, the processor controls each of the plurality of ultrasonic array elements to emit a second ultrasonic wave at a second frequency, so that the second ultrasonic wave drives the target area to vibrate. Among them, the piezoelectric element is conformal to the target area of the target object.

[0084] In operation S520, the processor controls the ultrasonic array to emit a plane detection wave to obtain the echo signal of the piezoelectric element based on the plane detection wave.

[0085] In operation S530, the processor generates a stress change image of the piezoelectric element according to the echo signal. Among them, the stress change image characterizes the elastic state of the target area adjacent to the piezoelectric element.

[0086] In operation S540, the processor determines the evaluation result regarding the target area according to the stress change image of the piezoelectric element.

[0087] According to an embodiment of the present disclosure, the processor can control each of the plurality of ultrasonic array elements to emit a second ultrasonic wave at a second frequency, so that the second ultrasonic wave drives the target area to vibrate, thereby generating an acoustic radiation force.

[0088] According to an embodiment of the present disclosure, the acoustic radiation force can drive the target area and the piezoelectric element to vibrate. Therefore, a plane detection wave can be emitted by the ultrasonic array, the vibration of the piezoelectric element can be detected, and the echo signal can be obtained.

[0089] According to an embodiment of the present disclosure, since the target area changes under electrical stimulation, the stress of the piezoelectric sheet will change. Therefore, the echo signal can be analyzed to generate an image of the stress change of the piezoelectric sheet, and the evaluation result of the target area can be determined by analyzing the stress change image of the piezoelectric sheet.

[0090] According to an embodiment of the present disclosure, through the device provided by the embodiment of the present disclosure, the efficient electrostimulation regulation of the ultrasonic array driving the piezoelectric sheet and the real-time in-situ wireless elasticity detection method based on the ultrasonic array can be combined. Finally, through the cooperation of the piezoelectric sheet conformal with the target area and the ultrasonic array, the effective combination of ultrasonic-driven electrostimulation therapy and real-time in-situ monitoring of the target area evaluation is realized.

[0091] According to an embodiment of the present disclosure, among the multiple ultrasonic array elements, there are a first ultrasonic array element and a second ultrasonic array element. Controlling each of the multiple ultrasonic array elements to emit second ultrasonic waves at a second frequency by a processor may include controlling the first ultrasonic array element to emit first sub-ultrasonic waves at a first phase of the second frequency; controlling the second ultrasonic array element to emit second sub-ultrasonic waves at a second phase of the second frequency, so that the first sub-ultrasonic waves and the second sub-ultrasonic waves are focused in the target area and generate acoustic radiation force to drive the target area to vibrate.

[0092] Figure 6 Schematically shows a schematic diagram of the principle of a method for evaluating the effect using an ultrasonic-driven electrostimulation device according to an embodiment of the present disclosure.

[0093] As Figure 6 shown, the ultrasonic array elements of the same frequency can form a focusing source 1 and a focusing source 2. By using different focusing sources, ultrasonic difference frequency waves can be generated, and then focused in the target area and generate acoustic radiation force at the focal point. The center frequencies of the ultrasonic difference frequency wave focusing source 1 and the focusing source 2 are respectively and , and the frequency difference is very small. The total sound pressure of the first sub-ultrasonic wave and the second sub-ultrasonic wave on the focal plane is:

[0094] (4)

[0095] Wherein, represents the sound pressure of the first sub-ultrasonic wave, represents the sound pressure of the second sub-ultrasonic wave, represents time, represents the position of a certain point on the focal plane; and respectively represent the amplitude functions of the sound pressures generated by the first sub-ultrasonic wave and the second sub-ultrasonic wave; and respectively represent the first phase of the first sub - ultrasonic wave and the second phase of the second sub - ultrasonic wave.

[0096] According to an embodiment of the present disclosure, the acoustic radiation force is caused by the change in the acoustic field energy of the incident ultrasonic wave. Considering a plane ultrasonic wave interacting with a plane object with zero thickness, arbitrary shape, and boundary impedance, the object will undergo scattering and absorption. The acoustic radiation force vector generated by this interaction has a component in the direction of the ultrasonic beam and another transverse component, which are expressed as follows:

[0097] (5)

[0098] where represents the drag coefficient vector, which can represent the acoustic absorption and acoustic scattering characteristics of the target area. One of its components is in the direction of the incident ultrasonic beam, and the other component is in the transverse direction. represents the projected area of the object, represents the average energy density of the incident ultrasonic wave on the object.

[0099] At the focal plane, the surface element located at is perpendicular to the incident ultrasonic wave, and the acoustic radiation force it receives only has a component along the direction of ultrasonic wave propagation. Its alternating component can be expressed as: (6)

[0100] where the integral of

[0101] with respect to is obtained as where and are respectively the amplitude (usually complex) of the total acoustic radiation force and the corresponding phase.

[0102] On the premise that the duration of the acoustic radiation force is the same, compared with the traditional acoustic radiation force with a constant amplitude, the potential advantage of the confocal difference - frequency ultrasonic wave is that it can provide a higher - amplitude acoustic radiation force within a certain time limit, enabling the energy of the acoustic radiation force to be more concentratedly transmitted into the elastic medium in a short time, thereby increasing the displacement generated in the elastic medium and improving the detection sensitivity.

[0103] To improve the spatial resolution of the dynamic acoustic radiation force for detecting tissues, the dynamic stress field is restricted to a very small area in three - dimensional space. Two focused sources with slightly different frequencies in the ultrasonic array are used to generate two unmodulated first sub - ultrasonic waves and second sub - ultrasonic waves, which intersect in the focal area. The amplitude - modulated field is generated only in the interference area around the focal area of the ultrasonic beam, thereby forming a small resolution unit. Assume that the ultrasonic beam propagates in a lossless medium along the rectangular coordinate system along the Propagating in a direction with the focal point located at a plane. Define the position on the focal plane located at The acoustic radiation force acoustic pressure signal detected by the ultrasonic array at a distance of from the confocal region comprehensively reflects the acoustic properties and elastomechanical properties of the tissue in the confocal region. The acoustic pressure at the ultrasonic array receiver can be expressed as:

[0104] (7)

[0105] where represents the density of the target area, represents the influence of the target area on the ultrasonic sound field, called the medium transfer function.

[0106] When the acoustic pressure distributions of two beams of exciting ultrasonic waves in their confocal regions are determined, the differences in acoustic radiation force directly reflect the changes in the acoustic (acoustic absorption and scattering) characteristics of the tissue in the focal region. The tissue in the confocal region vibrates back and forth along the acoustic axis under the action of the alternating radiation force, thereby radiating sound waves with an angular frequency of to the surrounding medium, that is, the acoustic radiation force signal. Since the frequency of this signal is low and the attenuation is very small when propagating in the tissue, it can be conveniently detected by the ultrasonic array.

[0107] Define the drag coefficient distribution of a unit target located at position on the focal plane as:

[0108] (8)

[0109] It can be considered that the projected area is . Calculate the pressure field, then the complex amplitude of the normal component of the force at the unit target point can be expressed as:

[0110] (9)

[0111] where , , represent the oscillator velocity amplitude on the surface of the first ultrasonic element, the second frequency of the first ultrasonic element, and the aperture size of the first ultrasonic element, , , represent the oscillator velocity amplitude on the surface of the second ultrasonic element, the second frequency of the second ultrasonic element, and the aperture size of the second ultrasonic element, represents the total aperture size of the first ultrasonic element and the second ultrasonic element, represents the imaginary unit in the complex number, Represents the radial distance of the second ultrasonic wave. The stress field of the piezoelectric element is confined to the area near the ultrasonic beam focus point ( ), and weakens as the radial distance increases. The higher the ultrasonic frequency, the smaller the lateral range of the stress field, and thus the smaller the diameter of the resolution unit.

[0112] Losses in the propagation path cause attenuation of the two ultrasonic waves, so the acoustic radiation force generated by the remaining ultrasonic energy is smaller. Energy losses in the medium also cause separate radiation stresses in the medium along the ultrasonic path. However, since the two ultrasonic waves propagate along different paths in the form of continuous waves, the main acoustic radiation force they generate on the medium is stable and does not cause vibration of the object or medium. The dynamic acoustic radiation force is only generated in the interference area around the focal area, which is another advantage of using two unmodulated focused ultrasonic beams instead of a single focused ultrasonic beam.

[0113] According to an embodiment of the present disclosure, generating an image of the stress change of the piezoelectric element by the processor based on the echo signal may include determining, by the processor, the acoustic emission amplitude at different positions of the piezoelectric element according to the echo signal; generating an image of the stress change of the piezoelectric element according to the acoustic emission amplitude at different positions of the piezoelectric element.

[0114] According to an embodiment of the present disclosure, in order to generate an image of the elastic stress distribution of the piezoelectric element, scanning may be performed on the common surface of the piezoelectric element. For example, detection may be performed by emitting plane waves at different angles, and the acoustic emission amplitudes at different positions may be recorded , keeping unchanged. For the transverse view image, the scanning plane is the focal plane ; for the parallel view, the scanning plane is plane. In traditional ultrasonic imaging, these two views are respectively called C-scan and B-scan. The present disclosure mainly discusses transverse view imaging. In this case, the acoustic emission data obtained by vibrating the target area at the point corresponds to the corresponding point in the image.

[0115] Related to the piezoelectric element under test are the resistance coefficients and (assuming is independent of the target area under test). Therefore, the function of the piezoelectric element under test is defined as the spatial distribution of these terms:

[0116] (10)

[0117] where the variables and are used to represent the relationship between and and the position. Among them, It means the total acoustic wave outflow at a point when a unit force is applied at that point. The piezoelectric sheet to be measured is scanned point by point with two confocal ultrasonic beams, and the amplitude or phase corresponding to each point is imaged in gray scale. By performing beam synthesis on multiple consecutive echo signals, a stress change image reflecting the stress change of the piezoelectric sheet can be generated through algorithms such as autocorrelation and shear wave velocity estimation. For example, it can be a two-dimensional gray scale image. Furthermore, the elastic change of the target area can be obtained in real time in situ based on the stress change of the piezoelectric sheet, thereby realizing in situ evaluation of the target area.

[0118] Figure 7 Schematically shows a system for ultrasonic-driven electrical stimulation and effect evaluation according to an embodiment of the present disclosure.

[0119] As Figure 7 shown, the system 700 includes an ultrasonic array 710, a piezoelectric sheet 720, a power management module 730, and a data processing module 740. The ultrasonic array 710 includes a plurality of ultrasonic array elements and can be placed on the skin surface corresponding to the target area of the target object. The piezoelectric sheet 720 can be arranged at the position of the target area and can conform to the target area. The power management module 730 includes a high-voltage switching switch unit, a 128-channel transmitting unit, a 64-channel receiving unit, a field programmable gate array (FPGA) unit, and a USB3.0 chip unit. By sending instructions to the power management module 710 through the data processing module 740, the power management module 730 executes the corresponding instructions to control the ultrasonic array and the piezoelectric sheet, thereby completing the electrical stimulation and effect evaluation of the target area. The specific control process can refer to the description of other embodiments of the present disclosure and will not be elaborated here. Among them, the power management module 730 and the data processing module 740 can be equivalent to the processor of the ultrasonic-driven electrical stimulation device.

[0120] According to an embodiment of the present disclosure, the ultrasonic-driven electrical stimulation and effect evaluation system provided by the embodiment of the present disclosure effectively combines ultrasonic-driven electrical stimulation treatment and real-time in situ monitoring of tissue status through the cooperation of a conformal piezoelectric sheet and an ultrasonic array, improves the stimulation effect on the target area, and can realize the combination of electrical stimulation and evaluation using the same set of system, which is convenient to operate.

[0121] The above describes the embodiments of the present disclosure. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described separately above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. Without departing from the scope of the present disclosure, those skilled in the art can make various substitutions and modifications, and these substitutions and modifications should fall within the scope of the present disclosure.​

Claims

1. An ultrasonic-driven electrical stimulation device, comprising an ultrasonic array, a piezoelectric sheet, and a processor; Among them, The processor is electrically connected to the ultrasonic array. The piezoelectric sheet is located in a target area of a target object. The ultrasonic array includes a plurality of ultrasonic elements. The processor is configured to control each of the plurality of ultrasonic elements in the ultrasonic array to emit a first ultrasonic wave at a first frequency. The first ultrasonic wave at the first frequency causes the piezoelectric sheet to generate an electrical stimulation acting on the target area.

2. The apparatus according to claim 1, wherein, The ultrasonic array further includes a first flexible encapsulation layer and a second flexible encapsulation layer. The ultrasonic elements are disposed between the first flexible encapsulation layer and the second flexible encapsulation layer. A first flexible metal electrode corresponding to the ultrasonic element is disposed on a surface of the first flexible encapsulation layer adjacent to the ultrasonic element. A second flexible metal electrode corresponding to the ultrasonic element is disposed on a surface of the second flexible encapsulation layer adjacent to the ultrasonic element.

3. The device according to claim 1, wherein The material of the piezoelectric sheet includes a material that can be degraded; The piezoelectric sheet includes a piezoelectric thin film, nanowires disposed on the piezoelectric thin film, and a coating layer disposed on the piezoelectric thin film and the nanowires.

4. The apparatus according to claim 3, wherein, The material of the piezoelectric sheet includes one of poly-L-lactic acid and poly-L-lactic acid; 5. The device according to any one of claims 1 to 3, wherein The first frequency is determined according to the distance between the piezoelectric sheet and the ultrasonic array and the elastic stress of the piezoelectric sheet; The first frequency is determined by the following operations: According to the distance between the piezoelectric sheet and the ultrasonic array and the attenuation index of the first ultrasonic wave in the target object, determine the attenuation amount of the first ultrasonic wave; According to the attenuation amount of the first ultrasonic wave, determine the compensation frequency of the ultrasonic element; According to the elastic stress, area, density, and vibration mode of the piezoelectric sheet, determine the resonance frequency of the piezoelectric sheet; According to the compensation frequency of the ultrasonic element and the resonance frequency of the piezoelectric sheet, determine the first frequency of each of the plurality of ultrasonic elements.

6. The device according to any one of claims 1 to 3, wherein, The processor is configured to, by adjusting the phases of the first ultrasonic waves emitted by each of the plurality of ultrasonic elements, make the first ultrasonic waves emitted by each of the plurality of ultrasonic elements uniformly distributed on the surface of the piezoelectric sheet, so that the piezoelectric sheet generates an electrical stimulation acting on the target area; or The processor is configured to, by adjusting the phases of the first ultrasonic waves emitted by each of the plurality of ultrasonic elements, make the first ultrasonic waves emitted by each of the plurality of ultrasonic elements focused on a target point on the surface of the piezoelectric sheet, so that the piezoelectric sheet generates an electrical stimulation acting on the target area.

7. The device according to any one of claims 1 to 3, wherein The processor is further configured to control each of the plurality of ultrasonic elements to emit a second ultrasonic wave at a second frequency, so as to drive the target area to vibrate, control the ultrasonic array to emit a plane detection wave, obtain an echo signal of the piezoelectric sheet based on the plane detection wave, generate a stress change image of the piezoelectric sheet according to the echo signal, and determine an evaluation result regarding the target area by the processor according to the stress change image of the piezoelectric sheet.

8. A method for effect evaluation using the device according to any one of claims 1 to 7, wherein, The device includes an ultrasonic array, a piezoelectric element, and a processor. The processor is electrically connected to the ultrasonic array. The ultrasonic array includes a plurality of ultrasonic array elements. The method includes: Controlling, by the processor, the plurality of ultrasonic array elements to each emit second ultrasonic waves at a second frequency, so that the second ultrasonic waves drive the target area to vibrate, wherein the piezoelectric element is conformal with the target area of the target object; Controlling, by the processor, the ultrasonic array to emit a planar detection wave to obtain an echo signal of the piezoelectric element based on the planar detection wave; Generating, by the processor, a stress change image of the piezoelectric element according to the echo signal, wherein the stress change image characterizes the elastic state of the target area adjacent to the piezoelectric element; Determining, by the processor, an evaluation result regarding the target area according to the stress change image of the piezoelectric element.

9. The method according to claim 1, wherein Among the plurality of ultrasonic array elements, there are a first ultrasonic array element and a second ultrasonic array element. The controlling, by the processor, the plurality of ultrasonic array elements to each emit second ultrasonic waves at a second frequency includes: Controlling, by the processor, the first ultrasonic array element to emit a first sub-ultrasonic wave at a first phase of the second frequency; Controlling, by the processor, the second ultrasonic array element to emit a second sub-ultrasonic wave at a second phase of the second frequency, so that the first sub-ultrasonic wave and the second sub-ultrasonic wave are focused in the target area and generate an acoustic radiation force to drive the target area to vibrate.

10. The method according to claim 6, wherein, The generating, by the processor, the stress change image of the piezoelectric element according to the echo signal includes: Determining, by the processor, the acoustic emission amplitudes at different positions of the piezoelectric element according to the echo signal; Generating the stress change image of the piezoelectric element according to the acoustic emission amplitudes at different positions of the piezoelectric element.

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