Joint synovial ablation flexible focusing ultrasonic transducer and dynamic compensation method thereof

Abstract

The invention belongs to the technical field of ultrasonic transducer focusing, and provides a joint synovial membrane ablation flexible focusing ultrasonic transducer and a dynamic compensation method thereof.The ultrasonic transducer comprises a sensing wafer unit and a phased array control unit, and each sensing wafer can independently move relatively to adapt to the shape of the joint skin contour; the phased array control unit controls the excitation time and the excitation sequence of each sensing wafer through a focusing rule so as to control the deflection angle and the focusing depth of a finally synthesized ultrasonic wave beam, so that the ultrasonic wave beam is deflected and focused to a target focus area; the dynamic compensation method comprises the following steps: acquiring a displacement value of each displacement sensor; calculating the relative displacement of each sensing wafer; calculating ultrasonic transmission time corresponding to the relative displacement of each sensing wafer as a focusing rule time correction value; and superposing the focusing rule time correction value into a control time function of the focusing rule to complete dynamic compensation of the joint synovial membrane ablation flexible focusing ultrasonic transducer.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic transducer focusing technology, and in particular to a flexible focusing ultrasonic transducer for joint synovial ablation and a dynamic compensation method thereof. Background Art

[0002] Arthritis is currently one of the most common chronic diseases. According to data released by the National Health Commission in 2023, the prevalence of osteoarthritis in my country is as high as 15%, with more than 200 million patients. The prevalence of rheumatoid arthritis is about 1.5%, with about 20 million patients. Although the prevalence of hemophilic arthritis is only 2.73 / 100,000, the patients are young and the disability rate is as high as 70%. Problems such as joint swelling, pain, and dysfunction plague arthritis patients, seriously affecting their lives and work, and even affecting the growth and development of children. Although there are many clinical diagnosis and treatment methods for arthritis, there are still problems such as difficult diagnosis, complex operation, high trauma, and many complications.

[0003] See also Figure 1 The inner surface of the joint, except for the cartilage, is covered with a thin connective tissue membrane, the synovium, which consists of a surface lining layer and a deep sublining layer. Under normal conditions, the synovial lining layer is arranged with 1 to 3 layers of cells, namely macrophage-like synoviocytes, i.e., type A synoviocytes, and fibroblast-like synoviocytes, i.e., type B synoviocytes.

[0004] In the state of joint inflammation, the number of synovial lining cell layers increases, inflammatory cell infiltration increases, synovial neovascularization and fibrosis occur, and synovial congestion and swelling occur, which eventually lead to a significant increase in synovial thickness. This pathological phenomenon is called synovial hyperplasia. Synovial hyperplasia causes disorder in joint lubricants and matrix components, thereby promoting inflammatory reactions and leading to destruction of articular cartilage and bone. In other words, synovial hyperplasia is an inevitable stage in the development of arthritis and plays a key role in the course of the disease. Therefore, the key to the treatment of arthritis is to remove the hyperplastic synovium as soon as possible to avoid further destruction of articular cartilage and subchondral bone, thereby delaying the progression of arthritis and maintaining or even improving joint mobility.

[0005] One of the main ways to remove hyperplastic synovium is to use high-intensity focused ultrasound (HIFU) to ablate the synovial lesion area. HIFU technology uses high-intensity ultrasound as an energy source, and focuses the ultrasound to the lesion site in the body through an external transmitter. These ultrasound waves are converted into heat energy at the focal point, generating high temperatures (65℃-100℃), which immediately causes coagulative necrosis of the lesion tissue. The focusing of ultrasound is similar to the focusing of light by a magnifying glass. A focused ultrasound transducer composed of self-focusing piezoelectric ceramics is used. Its planar transducer, acoustic focusing lens and electronic phased array device are used to focus ultrasound waves and generate a focus, and the energy is transferred to the target tissue, causing the target tissue to rise in temperature, thereby achieving ablation. This type of ultrasound focusing transducer has the advantages of small size, strong sound, low loss, concentrated energy and adjustable focus.

[0006] However, the existing focused ultrasound synovial resection has the following disadvantages: ① The existing focused ultrasound transducers are all rigid transducers. When the acoustic coupling agent between the skin is insufficient, it is easy to cause the sound beam to defocus, and the sound energy is deposited on the skin surface, causing skin burns; ② For some severely deformed joints, the existing rigid transducers cannot fit the joint skin and cannot be accurately focused for ablation treatment; ③ Since the excitation voltage is very high, the existing high-energy focused ultrasound transducers can only be used for treatment and cannot be used for imaging. The current operation method is to use MRI or ultrasound equipment for examination after a period of high-energy focused ultrasound treatment. However, since the target lesion area of ​​the bone and joint cannot be accurately focused, this will cause problems such as treatment deviation, insufficient treatment or excessive treatment. Summary of the invention

[0007] The purpose of the present invention is to provide a flexible focused ultrasound transducer for joint synovial ablation and a dynamic compensation method thereof. On the one hand, the flexible sensing chip unit can be set to make the transducer more fit the patient's joint contour shape; on the other hand, the sensing chip can be controlled to deflect and focus on the target lesion area.

[0008] The present invention solves the technical problem and adopts the following technical solution: In one aspect, the present invention provides a flexible focused ultrasound transducer for joint synovial ablation, comprising: A sensor chip unit, comprising a plurality of sensor chips, each of which can independently move relative to the other to adapt to the shape of the joint skin contour; The phased array control unit is used to control the excitation time and excitation order of each sensor element through the focusing law to control the deflection angle and focusing depth of the final synthesized ultrasonic beam, so that the ultrasonic beam is deflected and focused to the target lesion area.

[0009] As a further optimization, the upper surface of each sensor chip is used to flexibly fit the joint skin, and the lower surface is installed on the sensor handle through a flexible support frame.

[0010] As a further optimization, a support sleeve and a displacement sensor are connected below each sensing wafer, the support sleeve includes a support sleeve inner cylinder and a support sleeve outer cylinder, the displacement sensor is arranged in the support sleeve inner cylinder, a sensing wafer is connected to the top of the displacement sensor, a pressure sensor is connected to the bottom, and the support sleeve outer cylinder wraps the support sleeve inner cylinder; Each sensor chip is on the same horizontal plane when not under force. When the sensor chip is under force, the sensor chip compresses the displacement sensor and moves downward. Due to the limiting effect of the support sleeve, the sensor chip can only move vertically downward without generating torsional deflection.

[0011] As a further optimization, the displacement sensor is a spring or optical fiber displacement sensor.

[0012] As a further optimization, when the displacement sensor is a spring and the sensing wafer is forced to move downward, the movement distance of each wafer is calculated based on Hooke's law and the detection value of the pressure sensor.

[0013] As a further optimization, an ultrasonic excitation system is also included, wherein the ultrasonic excitation system includes a high-energy excitation module and a low-energy excitation module, each excitation module is connected to a control switch, and the working state and the dormant state of each excitation module are controlled by the control switch; Before the ultrasonic beam is deflected and focused to the target lesion area for ablation, a low-energy excitation module is used to image and determine the location of the lesion area using a flexible focused ultrasonic transducer, and then the high-energy excitation module is switched to achieve high-energy ultrasonic ablation of the target lesion area through the ultrasonic beam.

[0014] As a further optimization, a signal attenuator and a signal acquisition unit are also included; When switching to the high-energy excitation module, a signal attenuator is set in the signal acquisition circuit of each sensor chip. The received high-energy ultrasonic signal is attenuated by the signal attenuator and transmitted to the signal acquisition unit to realize real-time ultrasonic imaging.

[0015] On the other hand, the present invention also provides a dynamic compensation method for a flexible focused ultrasound transducer for joint synovial ablation, which is applied to the flexible focused ultrasound transducer for joint synovial ablation and comprises the following steps: Place the joint synovial membrane ablation flexible focused ultrasound transducer close to the joint to be treated, and the instrument host obtains the displacement value of each displacement sensor; Each sensor chip is numbered, and the relative displacement of each sensor chip is calculated by taking the sensor chip numbered 1 as a reference. According to the relative displacement of each sensor chip and the propagation speed of ultrasound in the human body, the ultrasonic transmission time corresponding to the relative displacement of each sensor chip is calculated, and the ultrasonic transmission time is the focal law time correction value of each chip; The time correction value of the focal law is superimposed on the control time function of the focal law to complete the dynamic compensation of the flexible focused ultrasound transducer for joint synovial ablation.

[0016] As a further optimization, assuming that the number of sensor wafers is N, the sensor wafer numbered 1 is used as a reference to calculate the relative displacement of the Nth sensor wafer, and the calculation formula is: ,

[0017] The calculation formula of the focal law time correction value is: ,

[0018] T N Indicates the correction time of the Nth sensor chip, D N Represents the relative displacement of the Nth sensor element, V It indicates the speed of ultrasound propagation in the human body. D 1x represents the displacement value of the displacement sensor corresponding to the sensor chip numbered 1, D Nx represents the displacement value of the displacement sensor corresponding to the sensing wafer numbered N; The excitation time of the sensor element N corresponding to the modified focusing law is: ,

[0019] t N It indicates the excitation time of sensor element N when the transducer is in the initial position (all sensor elements are at the same horizontal position).

[0020] The beneficial effects of the present invention are: through the above-mentioned flexible focused ultrasonic transducer for joint synovial ablation and dynamic compensation method, the flexible sensing crystal unit can be set to make the transducer fit the contour of the patient's joint more closely, avoiding the problem of defocusing the sound beam and depositing the sound energy on the skin surface, causing skin burns when the acoustic coupling agent between the traditional rigid focused ultrasonic transducer and the skin is insufficient. At the same time, it can target some severely deformed joints to avoid the problem that the existing rigid transducer cannot fit the joint skin and cannot perform ablation treatment; in addition, the present invention can accurately control the deflection and focusing of the sensing crystal to the target lesion area. At the same time, the present invention can image in real time, judge the ablation effect of the lesion area in real time, and guide the focusing angle and focusing depth of the ablation flexible focused ultrasonic transducer in real time according to the ablation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the destruction of articular cartilage and bone caused by synovial hyperplasia in the background technology; Figure 2 It is a schematic diagram of fitting a flexible focused ultrasound transducer to a joint contour in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the overall composition of the flexible focused ultrasound transducer for joint synovial ablation in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the phased array focused ultrasound principle in Embodiment 1 of the present invention; Figure 5 It is a schematic diagram of the arrangement structure of conventional focused ultrasound and flexible phased array focused ultrasound sensor chips in Embodiment 1 of the present invention; Figure 6 Schematic diagram of the structure of a flexible focused ultrasonic transducer in Embodiment 1 of the present invention; Figure 7 Schematic diagram of the sensor wafer support structure and the sensor wafer movement distance detection in the first embodiment of the present invention; Figure 8 This is a flow chart of a dynamic compensation method for a flexible focused ultrasound transducer for joint synovial ablation in Embodiment 2 of the present invention; Fig. 9 is the focusing law of the flexible array focused ultrasonic transducer in the initial state in the second embodiment of the present invention; Fig.10 This is the focusing law when the flexible array focused ultrasonic transducer in the second embodiment of the present invention is close to the outer contour of a joint. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0023] Embodiment 1

[0024] See also Figure 2 and Figure 3 This embodiment provides a flexible focused ultrasound transducer for joint synovial ablation, comprising: A sensor chip unit, comprising a plurality of sensor chips, each of which can independently move relative to the other to adapt to the shape of the joint skin contour; The phased array control unit is used to control the excitation time and excitation order of each sensor element through the focusing law to control the deflection angle and focusing depth of the final synthesized ultrasonic beam, so that the ultrasonic beam is deflected and focused to the target lesion area.

[0025] This embodiment uses flexible focused ultrasound that can fit closely to the joint skin for synovial ablation diagnosis and treatment. The essence of focused ultrasound is phased array ultrasound. The deflection angle and focusing depth of the ultrasonic beam can be controlled by focusing law. The principle is as follows: by changing the excitation time and excitation order of each chip, the direction and focusing characteristics of the final synthesized sound beam can be controlled. Figure 4 As shown, if a focused ultrasound deflected to the right is to be generated, first control chip No. 1 to excite ultrasound, and after a delay of a period of time, control chips No. 2 to 8 to excite ultrasound in turn, so as to realize an ultrasonic beam deflected to the right by a fixed angle and a fixed focusing depth.

[0026] like Figure 5 As shown, the most significant feature of the flexible focused ultrasound transducer of this embodiment, compared with the traditional rigid focused ultrasound, is that each crystal element can independently move relative to each other to adapt to the shape of the joint skin contour.

[0027] like Figure 6 and Figure 7As shown, the sensor chip of the flexible focusing sensor of this embodiment is connected with a support sleeve and a spring below. Under the action of the sleeve and the spring, each sensor chip can be ensured to be on the same horizontal plane when not under force; the support sleeve is composed of an outer cylinder and an inner cylinder. When the sensor chip is under force, the sensor chip will compress the spring and move downward (this direction only indicates the direction when the sensor handle is in contact with the human body joint as a whole, the purpose is to facilitate the description of the movement direction of the sensor chip). Due to the limiting effect of the support sleeve, the sensor chip can only move vertically downward without torsion deflection, etc. The structural size of the sleeve also determines the movable distance of each sensor chip.

[0028] Therefore, in this embodiment, the upper surface of each sensor chip is used to flexibly fit the joint skin, and the lower surface is installed on the sensor handle through a flexible support frame. In addition, a support sleeve and a displacement sensor are connected below each sensor chip, and the support sleeve includes a support sleeve inner tube and a support sleeve outer tube. The displacement sensor is arranged in the support sleeve inner tube, and a sensor chip is connected to the top of the displacement sensor, and a pressure sensor is connected to the bottom. The support sleeve outer tube wraps the support sleeve inner tube; each sensor chip is on the same horizontal plane when not under force. When the sensor chip is under force, the sensor chip compresses the displacement sensor and moves downward. Through the limiting effect of the support sleeve, the sensor chip can only move vertically downward without torsional deflection.

[0029] It should be pointed out that the displacement sensor can be a spring or an optical fiber displacement sensor, etc. When a spring is used as a displacement sensor, in addition to obtaining the displacement of the sensing wafer, it can also compress the sensing wafer to make it fit closely with the outer contour of the joint; when the displacement sensor is a spring, and the sensing wafer is forced to move downward, based on Hooke's law, the movement distance of each wafer is calculated according to the detection value of the pressure sensor. Here, the spring has three functions: 1) to ensure that each sensing wafer is on the same horizontal plane in the initial state; 2) when ablation treatment is performed on synovitis, it can ensure that each sensing wafer fits closely with the joint; 3) when the spring is under force, it compresses the pressure sensor connected to its bottom. According to Hooke's law, the movement distance of each wafer can be calculated according to the detection value of the pressure sensor, providing an algorithm basis for subsequent ultrasonic focusing control.

[0030] In actual application, for a high-energy focused ultrasound transducer, due to its very high excitation voltage, the excited ultrasound energy is very high, and the ultrasound echo signal energy is also very high, which exceeds the upper limit of the acquisition range of the existing ultrasound imaging acquisition system, so it is impossible to image, which makes the process state of high-energy ultrasound ablation therapy unknown and uncontrollable. Therefore, in this embodiment, an ultrasound excitation system can also be included, the ultrasound excitation system includes a high-energy excitation module and a low-energy excitation module, each excitation module is connected to a control switch, and the working state and sleep state of each excitation module are controlled by the control switch; before the ultrasound beam is deflected and focused on the target lesion area for ablation, a low-energy excitation module is used, and a flexible focused ultrasound transducer is used for imaging and determining the position of the lesion area, and then the high-energy excitation module is switched to work, and high-energy ultrasound ablation of the target lesion area is achieved through the ultrasound beam. During the ultrasound ablation treatment process, the excitation module can be switched arbitrarily, so as to realize the alternating work of high-energy ultrasound treatment and low-energy ultrasound imaging, and finally realize the knowable and controllable ultrasound ablation treatment process. Here, the low-energy excitation module is used to determine the location of the lesion area using transducer imaging before ablation of the joint synovium. Otherwise, if high-energy imaging is performed directly, non-lesion area tissues may be burned.

[0031] It should be pointed out that if the alternating working modes of high-energy excitation ablation and low-energy excitation imaging are adopted, the ablation efficiency will be reduced and the thermal damage mechanism of the synovial tissue will be more complicated. Therefore, the present embodiment may also include a signal attenuator and a signal acquisition unit; when switching to the high-energy excitation module, a signal attenuator is arranged in the signal acquisition circuit of each sensor chip, and the received high-energy ultrasound signal is attenuated by the signal attenuator and transmitted to the signal acquisition unit to realize real-time ultrasound imaging.

[0032] Embodiment 2

[0033] Based on the first embodiment, this embodiment provides a dynamic compensation method for a flexible focused ultrasound transducer for synovial ablation of joints. Figure 8 , wherein the method comprises the following steps: S1. Place the flexible focused ultrasound transducer for joint synovial ablation close to the joint to be treated, and the instrument host obtains the displacement value of each displacement sensor; S2, numbering each sensor chip, taking the sensor chip numbered 1 as a reference, and calculating the relative displacement of each sensor chip; S3, according to the relative displacement of each sensor chip and the propagation speed of ultrasound in the human body, calculate the ultrasonic transmission time corresponding to the relative displacement of each sensor chip, and the ultrasonic transmission time is the focus law time correction value of each chip; S4. Superimpose the focal law time correction value into the focal law control time function to complete the dynamic compensation of the flexible focused ultrasound transducer for joint synovial ablation.

[0034] Since the relative position of each chip of the traditional rigid focused ultrasound sensor is fixed, the focusing law is consistent for different patients. However, for the flexible focused ultrasound sensor in this embodiment, the relative position of its sensing chip will change with the joint shape structure of different patients, and its focusing law control algorithm must also change accordingly to control the ultrasonic beam deflection and focus on the target lesion area.

[0035] See also Fig. 9 It can be seen that when the sensor chips of the ultrasonic transducer array are in the same horizontal plane, the existing focusing law (i.e., controlling the time sequence of the excitation pulses for exciting each sensor chip) can achieve precise control of the focus. Fig.10 It can be seen that by using the displacement data measured by the displacement sensor corresponding to each sensor chip, taking sensor chip No. 1 as the reference point, a sensor chip relative displacement data sequence is established, and then according to the propagation speed V of ultrasound in human tissue, the correction time of each sensor chip excitation pulse is calculated to obtain a new excitation pulse time sequence.

[0036] In this embodiment, each wafer of the flexible focused ultrasonic transducer is provided with a micro displacement sensor, and the displacement sensor may be a spring in this solution, or may be an optical fiber displacement sensor, etc.

[0037] See Table 1, which is a table of wafer displacement values ​​and time correction values. In this embodiment, first, assuming that the number of sensing wafers is N, the flexible focused ultrasound transducer is placed close to the patient's joint to be treated, and the instrument host obtains the displacement value D of each displacement sensor. Nx , taking the sensor chip numbered 1 as the reference, calculate the relative displacement of the Nth sensor chip, and the calculation formula is: , Table 1 Sensor chip displacement value and time correction value

[0038] Secondly, according to the relative displacement of each sensor chip and the propagation speed of ultrasound in the human body, the ultrasonic transmission time corresponding to the displacement of each sensor chip is calculated, and this time is the focus law time correction value of each sensor chip. After obtaining the time correction value, the correction value is superimposed on the control time function of the focus law, and the focus diagnosis and treatment of joints of any shape can be achieved.

[0039] The correction time calculation formula is: , TN Denotes the correction time of the Nth sensor chip, D N Represents the relative displacement of the Nth sensor element, V Indicates the propagation speed of ultrasound in the human body, D 1x represents the displacement value of the displacement sensor corresponding to the sensor chip numbered 1, D Nx represents the displacement value of the displacement sensor corresponding to the sensing wafer numbered N; Correspondingly, Fig.10 The focusing law in is: , t N It indicates the excitation time of sensor element N when the transducer is in the initial position (all sensor elements are at the same horizontal position).

[0040] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Flexible focused ultrasound transducer for joint synovial ablation, characterized in that: include: A sensor chip unit, comprising a plurality of sensor chips, each of which can independently move relative to the other to adapt to the shape of the joint skin contour; The phased array control unit is used to control the excitation time and excitation order of each sensor element through the focusing law to control the deflection angle and focusing depth of the final synthesized ultrasonic beam, so that the ultrasonic beam is deflected and focused to the target lesion area.

2. The flexible focused ultrasound transducer for joint synovial ablation according to claim 1, characterized in that: The upper surface of each sensor wafer is used to flexibly fit the joint skin, and the lower surface is installed on the sensor handle through a flexible support frame.

3. The flexible focused ultrasound transducer for joint synovial ablation according to claim 1, characterized in that: A support sleeve and a displacement sensor are connected below each sensing wafer. The support sleeve includes a support sleeve inner cylinder and a support sleeve outer cylinder. The displacement sensor is arranged in the support sleeve inner cylinder. A sensing wafer is connected to the top of the displacement sensor, and a pressure sensor is connected to the bottom. The support sleeve outer cylinder wraps the support sleeve inner cylinder. Each sensor chip is on the same horizontal plane when not under force. When the sensor chip is under force, the sensor chip compresses the displacement sensor and moves downward. Due to the limiting effect of the support sleeve, the sensor chip can only move vertically downward without generating torsional deflection.

4. The flexible focused ultrasound transducer for joint synovial ablation according to claim 3, characterized in that: The displacement sensor is a spring or optical fiber displacement sensor.

5. The flexible focused ultrasound transducer for joint synovial ablation according to claim 4, characterized in that: When the displacement sensor is a spring and the sensing wafer moves downward under force, the movement distance of each wafer is calculated based on Hooke's law and the detection value of the pressure sensor.

6. The flexible focused ultrasound transducer for joint synovial ablation according to claim 1, characterized in that: It also includes an ultrasonic excitation system, which includes a high-energy excitation module and a low-energy excitation module, each of which is connected to a control switch, and the working state and the dormant state of each excitation module are controlled by the control switch; Before the ultrasonic beam is deflected and focused to the target lesion area for ablation, a low-energy excitation module is used to image and determine the location of the lesion area using a flexible focused ultrasonic transducer, and then the high-energy excitation module is switched to achieve high-energy ultrasonic ablation of the target lesion area through the ultrasonic beam.

7. The flexible focused ultrasound transducer for joint synovial ablation according to claim 6, characterized in that: Also includes a signal attenuator and a signal acquisition unit; When switching to the high-energy excitation module, a signal attenuator is set in the signal acquisition circuit of each sensor chip. The received high-energy ultrasonic signal is attenuated by the signal attenuator and transmitted to the signal acquisition unit to realize real-time ultrasonic imaging.

8. A dynamic compensation method for a flexible focused ultrasound transducer for joint synovial ablation, applied to the flexible focused ultrasound transducer for joint synovial ablation according to any one of claims 1 to 7, characterized in that: The steps include: Place the joint synovial membrane ablation flexible focused ultrasound transducer close to the joint to be treated, and the instrument host obtains the displacement value of each displacement sensor; Each sensor chip is numbered, and the relative displacement of each sensor chip is calculated by taking the sensor chip numbered 1 as a reference. According to the relative displacement of each sensor chip and the propagation speed of ultrasound in the human body, the ultrasonic transmission time corresponding to the relative displacement of each sensor chip is calculated, and the ultrasonic transmission time is the focal law time correction value of each chip; The time correction value of the focal law is superimposed on the control time function of the focal law to complete the dynamic compensation of the flexible focused ultrasound transducer for joint synovial ablation.

9. The dynamic compensation method of the flexible focused ultrasound transducer for joint synovial ablation according to claim 8, characterized in that: Assuming that the number of sensor chips is N, the sensor chip numbered 1 is used as a reference to calculate the relative displacement of the Nth sensor chip, and the calculation formula is: ， The calculation formula of the focal law time correction value is: ， T N Denotes the correction time of the Nth sensor chip, D N represents the relative displacement of the Nth sensor chip, V represents the propagation speed of ultrasound in the human body, and D 1x represents the displacement value of the displacement sensor corresponding to the sensor chip numbered 1, D Nx represents the displacement value of the displacement sensor corresponding to the sensing wafer numbered N; The excitation time of the sensor element N corresponding to the modified focusing law is: ， t N Indicates the excitation time of sensor element N when the transducer is in the initial position.

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