Method for determining optimal bias voltage of CMUT and related device

Abstract

The invention discloses a CMUT optimal bias voltage determination method and a related device, the relation between bias voltage and receiving current is obtained by using an energy conversion principle, the optimal bias voltage is determined according to the maximum receiving current, and a CMUT optimal bias voltage determination device is designed to realize the method. The problem that the bias voltage can only be applied by means of an empirical value in the CMUT field is solved, and quantitative research on applying the optimal bias voltage to the CMUT structure is realized.

Description

Technical Field

[0001] The invention relates to a method for determining an optimal bias voltage of a CMUT and a related device, belonging to the field of capacitive micromechanical ultrasonic transducers. Background Art

[0002] Capacitive micromachined ultrasonic transducer (CMUT) is an ultrasonic sensor that uses film vibration to achieve mutual conversion between electrical signals and acoustic signals. It has the advantages of small size, large bandwidth, low power consumption, and high integration, and has good application prospects in the field of ultrasonic imaging. Existing studies have shown that high bias voltage is beneficial to improving the receiving performance of CMUT, but too high bias voltage will lead to problems such as strong nonlinearity and low reliability, and the bias voltage must be less than the collapse voltage of CMUT. For most CMUTs, the size of the applied bias voltage is unclear and can only be applied according to the empirical value based on its structure. At present, there is no theory to systematically analyze this. Summary of the invention

[0003] The present invention provides a method for determining an optimal bias voltage of a CMUT and a related device, which solves the problem disclosed in the background technology.

[0004] According to one aspect of the present disclosure, a method for determining an optimal bias voltage of a CMUT is provided, comprising: Traverse [0,V pull-in ] range, and the receiving current of the CMUT with each bias voltage applied is obtained by using the energy conversion principle; wherein, V pull-in is the collapse voltage of the CMUT with applied bias voltage; According to the bias voltage and the receiving current, a relationship between the bias voltage and the receiving current is constructed, and the bias voltage corresponding to the maximum receiving current in the relationship is used as the optimal bias voltage of the CMUT.

[0005] In some embodiments of the present disclosure, obtaining a receiving current of a CMUT to which a bias voltage is applied includes: determining an electromechanical conversion coefficient of the CMUT to which a bias voltage is applied; Determine the transmission power of the CMUT in the transmission mode to which the excitation signal is applied; wherein the excitation signal is an AC signal with the bias voltage as a baseline; Determine the transmitted acoustic power of the CMUT in the transmitting mode according to the electromechanical conversion coefficient and the transmitted electrical power; Determine the received sound power of the CMUT in the receiving mode according to the transmitted sound power and the attenuation factor of the sound wave signal in the medium; Determine the received electrical power of the CMUT in the receiving mode based on the electromechanical conversion coefficient and the received acoustic power; According to the received electric power, the received current of the CMUT is determined.

[0006] In some embodiments of the present disclosure, the formula for the electromechanical conversion coefficient is: ; In the formula, is the electromechanical conversion coefficient, is the average displacement generated by applying bias voltage to the CMUT, d 0 is the initial value of the effective depth between the upper and lower electrodes of the CMUT; If a bias voltage is applied to the vibrating membrane of the CMUT, ; In the formula, g is the initial value of the CMUT cavity depth, ε i is the relative dielectric constant of the CMUT insulation layer, t i is the thickness of the CMUT insulation layer.

[0007] In some embodiments of the present disclosure, the sum of the AC signal voltage and the bias voltage is the excitation signal voltage, the sum of the amplitude of the AC signal voltage and the bias voltage is the amplitude of the excitation signal voltage, and the amplitude of the excitation signal voltage does not exceed the collapse voltage of the CMUT; The transmission power is the maximum transmission power obtained according to the AC signal voltage and the CMUT impedance.

[0008] In some embodiments of the present disclosure, the transmitted acoustic power is the product of the electromechanical conversion coefficient and the transmitted electrical power; the received acoustic power is the product of the transmitted acoustic power and the attenuation factor; and the received electrical power is the product of the electromechanical conversion coefficient and the received acoustic power.

[0009] According to another aspect of the present disclosure, there is provided a device for determining an optimal bias voltage of a CMUT, comprising: Traverse the acquisition module and traverse [0,V pull-in ] range, and the receiving current of the CMUT with each bias voltage applied is obtained by using the energy conversion principle; wherein, V pull-in is the collapse voltage of the CMUT with applied bias voltage; The optimal determination module constructs a relationship between the bias voltage and the receiving current according to the bias voltage and the receiving current, and uses the bias voltage corresponding to the maximum receiving current in the relationship as the optimal bias voltage of the CMUT.

[0010] In some embodiments of the present disclosure, in the traversal acquisition module, acquiring the receiving current of the CMUT to which the bias voltage is applied includes: determining an electromechanical conversion coefficient of the CMUT to which a bias voltage is applied; Determine the transmission power of the CMUT in the transmission mode to which the excitation signal is applied; wherein the excitation signal is an AC signal with the bias voltage as a baseline; Determine the transmitted acoustic power of the CMUT in the transmitting mode according to the electromechanical conversion coefficient and the transmitted electrical power; Determine the received sound power of the CMUT in the receiving mode according to the transmitted sound power and the attenuation factor of the sound wave signal in the medium; Determine the received electrical power of the CMUT in the receiving mode based on the electromechanical conversion coefficient and the received acoustic power; According to the received electric power, the received current of the CMUT is determined.

[0011] According to another aspect of the present disclosure, a computer-readable storage medium is provided, which stores one or more programs, wherein the one or more programs include instructions, which, when executed by a computing device, cause the computing device to perform a method for determining a CMUT optimal bias voltage.

[0012] According to another aspect of the present disclosure, a computer device is provided, including one or more processors and one or more memories, one or more programs are stored in the one or more memories and are configured to be executed by the one or more processors, and the one or more programs include instructions for executing a method for determining an optimal bias voltage of a CMUT.

[0013] The beneficial effects achieved by the present invention are as follows: the present invention utilizes the energy conversion principle to obtain the relationship between the bias voltage and the receiving current, determines the optimal bias voltage according to the maximum receiving current, solves the problem that the bias voltage can only be applied based on empirical values ​​in the CMUT field, and realizes quantitative research on applying the optimal bias voltage in the CMUT structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A flow chart of a method for determining an optimal bias voltage for a CMUT; Figure 2 It is a structural diagram of CMUT; Figure 3 Schematic diagram of two types of excitation signals; Figure 4 is a graph showing the relationship between bias voltage and collapse voltage; Figure 5 Block diagram of an apparatus for determining an optimum bias voltage for a CMUT. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. It is obvious that the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present disclosure and its application or use. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0016] Unless otherwise specified, the relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure.

[0017] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0018] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0019] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0020] It should be noted that similar symbols and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it does not require further discussion in subsequent figures.

[0021] In order to solve the problem that bias voltage can only be applied based on empirical values ​​in the CMUT field, the present disclosure proposes a method and related device for determining the optimal bias voltage of CMUT, specifically, determining the optimal bias voltage by determining the relationship between the bias voltage and the receiving current.

[0022] Figure 1 FIG. 1 is a schematic diagram of an embodiment of a method for determining an optimal bias voltage of a CMUT disclosed in the present invention. Figure 1 The embodiments may be executed by an intelligent terminal or a controller.

[0023] like Figure 1 As shown, in step 1 of the embodiment, traverse [0, V pull-in ] range, and obtain the receiving current of the CMUT with each bias voltage applied; wherein, V pull-in is the collapse voltage of the CMUT with applied bias voltage.

[0024] It should be noted that if Figure 2As shown in FIG. 1 , the CMUT structure includes a vibrating film 101, a cavity 102, an insulating layer 103, a supporting structure 104, an upper electrode 105, a lower electrode 106, and a substrate 107. The vibrating film 101 is suspended above the cavity 102, and is connected to the fixed substrate 107 at the circumference through the supporting structure 104. Therefore, the vibrating film 101 should be regarded as a circumferential fixed support. There is an insulating layer 103 at the bottom of the cavity 102. The upper electrode 105 and the lower electrode 106 are respectively distributed above the vibrating film 101 and below the substrate 107. After applying voltage excitation to the upper electrode 105, an electrostatic force is generated between the upper electrode 105 and the lower electrode 106. F e , and form a capacitor. If the applied voltage excitation includes an AC term, it will cause the vibrating film 101 to vibrate, thereby emitting sound waves to the outside. This is the transmitting mode of the CMUT; if the applied voltage excitation does not include an AC term, when the vibrating film 101 receives an external sound signal and vibrates, the capacitor will generate current. This is the receiving mode of the CMUT.

[0025] In the receiving mode, a bias voltage is applied to the upper electrode 105 V dc Generate electrostatic force F e , vibrating film 101 in electrostatic force F e The lower electrode 106 is displaced by the action of , thereby reducing the cavity gap. At this time, the average capacitance between the upper electrode 105 and the lower electrode 106 of the CMUT C for: ; In the formula, ε 0 is the dielectric constant of vacuum (8.854×10 -12 F / m), A is the effective facing area of ​​the upper electrode 105 and the lower electrode 106, is the average displacement generated by applying bias voltage to the CMUT, d 0 is the initial value of the effective depth between the upper electrode 105 and the lower electrode 106 of the CMUT; ; In the formula, g is the initial depth of the CMUT cavity 102, ε i is the relative dielectric constant of the CMUT insulating layer 103, t i is the thickness of the CMUT insulating layer 103, the material of the insulating layer is usually SiO2, ε m is the relative dielectric constant of the vibrating film 101, tm is the thickness of the vibration film 101 .

[0026] Therefore, the bias voltage V dc The larger the value, the greater the displacement of the vibrating film 101, which reduces the distance between the upper electrode 105 and the lower electrode 106, thereby increasing the capacitance. I Relationship with capacitance: ; In the formula, Q is the amount of charge stored in the capacitor, t For time.

[0027] A smaller effective gap in the cavity 102 will make the capacitance change caused by the acoustic wave more significant, ultimately increasing the receiving current. In other words, a larger bias voltage V dc It is beneficial to improve the receiving performance. However, when the bias voltage V dc When a critical value is reached, the electrostatic force F e The elastic restoring force of the vibrating film 101 will no longer be balanced, causing the film to collapse. This voltage is called the collapse voltage (or pull-in voltage) V pull-in CMUT usually works in non-collapse mode, so the bias voltage V dc Need to be less than the collapse voltage.

[0028] In transmit mode, the bias voltage V dc On the basis of the above, an AC voltage is applied at the same time, that is, an AC signal with the bias voltage as the baseline is used as the excitation signal, and the excitation signal voltage is: V = V dc + V ac ( t ); In the formula, V is the excitation signal voltage, V ac ( t ) is the AC voltage.

[0029] The AC signal is a time-varying signal that causes the vibrating film 101 to vibrate, thereby emitting an acoustic signal. Similarly, the excitation signal voltage V Need to be less than the collapse voltage V pull-in .

[0030] It should be noted that the collapse voltage V of CMUTs with different structures pull-inis different, so its optimum bias voltage V dc It is not a fixed value, but according to experience, the bias voltage V dc With collapse voltage V pull-in There is a proportional relationship, but at present this relationship is not clear.

[0031] It should be noted that, from the excitation signal voltage formula, it can be seen that the bias voltage V dc The sum of the amplitude of the AC voltage applied afterwards cannot be greater than the collapse voltage V of the CMUT pull-in , otherwise the vibration film 101 will collapse.

[0032] Define α as the bias voltage V dc With collapse voltage V pull-in The value of α ranges from 0 to 1, so the bias voltage V dc The maximum value is the collapse voltage V pull-in ; That is, when the bias voltage V dc Less than the collapse voltage V pull-in When α<1, when the bias voltage V dc Equal to the collapse voltage V pull-in , that is, α=1.

[0033] Therefore, the bias voltage V dc The range is determined in [0,V pull-in ], by traversing [0,V pull-in ] and obtain the receiving current of the CMUT with each bias voltage applied.

[0034] It should be noted that in [0,V pull-in ] Multiple bias voltages can be determined with equal step lengths V dc , the process of obtaining the receiving current of the CMUT with applied bias voltage can be as follows: 1) Determine the electromechanical conversion coefficient of the CMUT with applied bias voltage.

[0035] It should be noted that the bias voltage V dc When applied to the CMUT, an electrostatic force is generated F e , causing the vibrating film 101 to move toward the insulating layer 103 at the bottom of the cavity 102, resulting in an average displacement of , the resulting electromechanical conversion coefficient can be expressed as: ; In the formula, is the electromechanical conversion coefficient.

[0036] It should be noted that if the bias voltage V dc is applied to the upper electrode, then: ; If the bias voltage is directly applied to the vibrating film 101 of the CMUT, the thickness of the vibrating film 101 itself will not affect the initial value of the effective depth, that is, the third term on the right side of the above equation is 0. d The formula for 0 can be changed to: .

[0037] 2) Determine the transmission power of the CMUT in the transmission mode to which the excitation signal is applied; wherein the excitation signal is an AC signal with the bias voltage as a baseline.

[0038] It should be noted that the excitation signal voltage amplitude is not greater than the collapse voltage, the sum of the AC signal voltage and the bias voltage is the excitation signal voltage, and the sum of the AC signal voltage amplitude and the bias voltage is the excitation signal voltage amplitude.

[0039] See Figure 3 , 301 in the figure is the bias voltage V dc ; 302 is a periodic square wave signal, the high level of the signal is V ac , the time occupied is 1 / f , low level is - V ac , the time occupied is 1 / f , there is 1 / f The time is empty; 303 is a periodic sine signal, the signal amplitude is V ac , the frequency is f , there is 1 / f The time of is empty; among them, f is the resonant frequency of the CMUT.

[0040] After the AC signal and the bias voltage are superimposed, the excitation signals 304 and 305 are obtained respectively; wherein the bias voltage shown in 301 V dc The square wave signal shown in 302 is superimposed to form the excitation voltage shown in 304; the bias voltage shown in 301 V dc The excitation voltage shown in 305 is formed by superposition with the sinusoidal signal shown in 303 .

[0041] For the two synthetic excitation voltages mentioned above, their baseline is the bias voltage V dc Rather than 0, although the bias voltage is given here V dc As well as two examples of AC signals, but for those skilled in the art who benefit from the disclosure of the present invention, similar principles can be extended to other time-varying excitation signals, such as pulse signals, triangular wave signals, etc.

[0042] It should be noted that the transmitted power is based on the AC signal voltage V ac The maximum transmitted electric power obtained by the CMUT impedance can be expressed as: ; In the formula, P e,T To transmit electrical power, Z is the CMUT impedance.

[0043] 3) Determine the transmitted acoustic power of the CMUT in the transmitting mode based on the electromechanical conversion coefficient and the transmitted electrical power.

[0044] It should be noted that after the conversion of electrical energy into mechanical energy, the mechanical power of the vibration film 101 when vibrating in the emission mode can be obtained, that is, the emission sound power. The emission sound power is specifically the product of the electromechanical conversion coefficient and the emission electrical power, which can be expressed by the formula: ; In the formula, P m,T is the emitted sound power.

[0045] 4) Determine the received sound power of the CMUT in the receiving mode based on the transmitted sound power and the attenuation factor of the sound wave signal in the medium.

[0046] It should be noted that the sound wave signal generated by the vibration is received by the CMUT again after being attenuated by the medium, and the mechanical power in the receiving mode is obtained, that is, the received sound power. The received sound power is specifically the product of the transmitted sound power and the attenuation factor, which can be expressed by the formula: ; In the formula, P m,R To receive the sound power, β is the attenuation factor; preferably, when the sound pressure of the sound wave signal is attenuated by -60dB, that is, attenuated to 1 / 1000 of the original value, according to the relationship between sound power and sound pressure, the attenuation factor of sound power is the square of the sound pressure attenuation factor, then it can be obtained β The value is 10 -6 .

[0047] 5) Determine the received electrical power of the CMUT in the receiving mode based on the electromechanical conversion coefficient and the received acoustic power.

[0048] It should be noted that after the received sound power is converted from mechanical energy to electrical energy, the received electrical power in the receiving mode is obtained, that is, the received electrical power. The received electrical power is specifically the product of the electromechanical conversion coefficient and the received sound power, which can be expressed by the formula: ; In the formula, P e,R To receive electrical power.

[0049] 6) Determine the receiving current of the CMUT based on the received electric power.

[0050] It should be noted that the receiving current can be expressed as: ; In the formula, i R To receive current.

[0051] return Figure 1 In step 2 of the embodiment, a relationship between the bias voltage and the receiving current is constructed according to the bias voltage and the receiving current, and the bias voltage corresponding to the maximum receiving current in the relationship is used as the optimal bias voltage of the CMUT.

[0052] It should be noted that in [0,V pull-in ] range, each bias voltage V dc There will be a corresponding receiving current, so the relationship between the bias voltage and the receiving current can be constructed. Specifically, a relationship curve can be constructed, and the maximum receiving current can be found from the relationship curve. The bias voltage corresponding to the maximum receiving current is the optimal bias voltage.

[0053] It should be noted that after the structure of CMUT is determined, the corresponding collapse voltage V pull-in It is also fixed, so the relationship between the received current and α can be further established.

[0054] The above method uses the energy conversion principle to obtain the relationship between the bias voltage and the receiving current, and determines the optimal bias voltage according to the maximum receiving current. It solves the problem that the bias voltage can only be applied based on empirical values ​​in the CMUT field, and realizes the quantitative research on applying the optimal bias voltage in the CMUT structure.

[0055] In order to verify the effectiveness of the above method, the above method is verified in a CMUT. The parameters of the CMUT are shown in Table 1.

[0056] Table 1 CMUT parameter table

[0057] Record bias voltage V dc And the corresponding receiving current value, can be constructed as follows Figure 4 The relationship between the receiving current and α is shown in the figure. It can be seen from the figure that when α=0.69, the CMUT can obtain a maximum receiving current of 1.51nA. At this time, the optimal bias voltage V dc =0.69 V pull-in =345V; it can be seen that the above method is accurate and effective.

[0058] The above method aims to solve the drawback of applying bias voltage through empirical values, which is beneficial to the design and test of CMUT. It gives the optimal bias voltage of CMUT of different structures and sizes in a theoretical way, so as to obtain the best receiving performance of CMUT.

[0059] Figure 5 FIG. 1 is a schematic diagram of an embodiment of a device for determining an optimal bias voltage of a CMUT disclosed in the present invention. Figure 5 The embodiment is a virtual device that can be loaded and executed by an intelligent terminal or a controller, including a traversal acquisition module and an optimal determination module.

[0060] The traversal acquisition module of the embodiment is configured to traverse [0, V pull-in ] range, and the receiving current of the CMUT with each bias voltage applied is obtained by using the energy conversion principle; wherein, V pull-in is the collapse voltage of the CMUT with applied bias voltage; The optimal determination module of the embodiment is configured to construct a relationship between the bias voltage and the receiving current according to the bias voltage and the receiving current, and use the bias voltage corresponding to the maximum receiving current in the relationship as the optimal bias voltage of the CMUT.

[0061] It should be noted that, in the traversal acquisition module, the receiving current of the CMUT with the bias voltage applied is obtained, including: determining the electromechanical conversion coefficient of the CMUT with the bias voltage applied; determining the transmitting electric power of the CMUT in the transmitting mode with the excitation signal applied; wherein the excitation signal is an AC signal with the bias voltage as the baseline; determining the transmitting acoustic power of the CMUT in the transmitting mode according to the electromechanical conversion coefficient and the transmitting electric power; determining the receiving acoustic power of the CMUT in the receiving mode according to the transmitting acoustic power and the attenuation factor of the acoustic wave signal in the medium; determining the receiving electric power of the CMUT in the receiving mode according to the electromechanical conversion coefficient and the receiving acoustic power; and determining the receiving current of the CMUT according to the received electric power.

[0062] Similar to the above method, the above device uses the energy conversion principle to obtain the relationship between the bias voltage and the receiving current, and determines the optimal bias voltage according to the maximum receiving current. This solves the problem that the bias voltage can only be applied based on empirical values ​​in the CMUT field, and realizes the quantitative research on applying the optimal bias voltage in the CMUT structure.

[0063] Based on the same technical solution, the present disclosure also relates to a computer-readable storage medium, which stores one or more programs, and the one or more programs include instructions. When the instructions are executed by a computing device, the computing device executes a method for determining an optimal bias voltage of a CMUT.

[0064] Based on the same technical solution, the present disclosure also relates to a computer device, including one or more processors and one or more memories, one or more programs are stored in the one or more memories and are configured to be executed by the one or more processors, and the one or more programs include instructions for executing a method for determining a CMUT optimal bias voltage.

[0065] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0066] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0067] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1A function specified in one or more boxes.

[0068] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0069] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A method for determining an optimal bias voltage of a CMUT, characterized in that: include: Traverse [0,V pull-in ] range, and using the energy conversion principle, obtain the receiving current of the CMUT to which each bias voltage is applied; Among them, V pull-in is the collapse voltage of the CMUT with applied bias voltage; According to the bias voltage and the receiving current, a relationship between the bias voltage and the receiving current is constructed, and the bias voltage corresponding to the maximum receiving current in the relationship is used as the optimal bias voltage of the CMUT.

2. The method for determining the optimal bias voltage of a CMUT according to claim 1, wherein: Obtain the receiving current of the CMUT with applied bias voltage, including: determining an electromechanical conversion coefficient of the CMUT to which a bias voltage is applied; Determine the transmission power of the CMUT in the transmission mode to which the excitation signal is applied; wherein the excitation signal is an AC signal with the bias voltage as a baseline; Determine the transmitted acoustic power of the CMUT in the transmitting mode according to the electromechanical conversion coefficient and the transmitted electrical power; Determine the received sound power of the CMUT in the receiving mode according to the transmitted sound power and the attenuation factor of the sound wave signal in the medium; Determine the received electrical power of the CMUT in the receiving mode based on the electromechanical conversion coefficient and the received acoustic power; According to the received electric power, the received current of the CMUT is determined.

3. The method for determining the optimal bias voltage of a CMUT according to claim 2, wherein: The formula for the electromechanical conversion coefficient is: ； In the formula, is the electromechanical conversion coefficient, is the average displacement generated by applying bias voltage to the CMUT, d 0 is the initial value of the effective depth between the upper and lower electrodes of the CMUT; If a bias voltage is applied to the vibrating membrane of the CMUT, ； In the formula, g is the initial value of the CMUT cavity depth, ε i is the relative dielectric constant of the CMUT insulation layer, t i is the thickness of the CMUT insulation layer.

4. The method for determining the optimal bias voltage of a CMUT according to claim 2, wherein: The sum of the AC signal voltage and the bias voltage is the excitation signal voltage, the sum of the amplitude of the AC signal voltage and the bias voltage is the amplitude of the excitation signal voltage, and the amplitude of the excitation signal voltage does not exceed the collapse voltage of the CMUT; The transmission power is the maximum transmission power obtained according to the AC signal voltage and the CMUT impedance.

5. The method for determining the optimal bias voltage of a CMUT according to claim 2, wherein: The transmitted acoustic power is the product of the electromechanical conversion coefficient and the transmitted electrical power; the received acoustic power is the product of the transmitted acoustic power and the attenuation factor; the received electrical power is the product of the electromechanical conversion coefficient and the received acoustic power.

6. A device for determining an optimal bias voltage of a CMUT, characterized in that: include: Traverse the acquisition module and traverse [0,V pull-in ] range, and using the energy conversion principle, obtain the receiving current of the CMUT to which each bias voltage is applied; Among them, V pull-in is the collapse voltage of the CMUT with applied bias voltage; The optimal determination module constructs a relationship between the bias voltage and the receiving current according to the bias voltage and the receiving current, and uses the bias voltage corresponding to the maximum receiving current in the relationship as the optimal bias voltage of the CMUT.

7. The device for determining the optimal bias voltage of a CMUT according to claim 6, characterized in that: The traversal acquisition module is used to obtain the receiving current of the CMUT to which the bias voltage is applied, including: determining an electromechanical conversion coefficient of the CMUT to which a bias voltage is applied; Determine the transmission power of the CMUT in the transmission mode to which the excitation signal is applied; wherein the excitation signal is an AC signal with the bias voltage as a baseline; Determine the transmitted acoustic power of the CMUT in the transmitting mode according to the electromechanical conversion coefficient and the transmitted electrical power; Determine the received sound power of the CMUT in the receiving mode according to the transmitted sound power and the attenuation factor of the sound wave signal in the medium; Determine the received electrical power of the CMUT in the receiving mode based on the electromechanical conversion coefficient and the received acoustic power; According to the received electric power, the received current of the CMUT is determined.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores one or more programs, and the one or more programs include instructions. When the instructions are executed by a computing device, the computing device executes any one of the methods of claims 1 to 5.

9. A computer device, characterized in that: include: One or more processors and one or more memories, one or more programs are stored in the one or more memories and are configured to be executed by the one or more processors, and the one or more programs include instructions for executing any of the methods described in claims 1 to 5.

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