Flexible CMUT patch for monitoring lower limb venous thrombosis and preparation method

Abstract

The embodiment of the invention discloses a flexible CMUT patch for monitoring lower limb venous thrombosis and a preparation method, and relates to the technical field of medical treatment. The flexible CMUT patch comprises a plurality of flexible CMUT patch units, and each flexible CMUT patch unit comprises an acceptor substrate, a donor substrate, a first electrode and a second electrode. The acceptor substrate sequentially comprises a flexible base material, a vibration film, a negative capacitance material layer and a silicon oxide layer, and a vacuum cavity gap is formed in the surface of the silicon oxide layer. The donor substrate includes an insulating layer and a conductive layer connected to each other. The first electrode is connected with the conductive layer, and the second electrode is connected with the side, away from the vibration film, of the flexible substrate. Therefore, the flexible CMUT patch adopts the flexible base material as a part of the acceptor substrate, and can adapt to the surfaces of various irregular structures, so that long-time, continuous and convenient monitoring can be realized, the convenience of seeing a doctor can be improved, the illness state can be early warned in time, and the delay of the optimal treatment opportunity can be avoided.

Description

Technical Field

[0001] The present application relates to the field of medical technology, and in particular to a flexible CMUT patch for monitoring lower extremity venous thrombosis and a preparation method thereof. Background Art

[0002] Lower extremity venous thrombosis is a common clinical disease that not only limits patients' daily activities but may also lead to more serious complications such as pulmonary embolism due to the movement of thrombi. Therefore, timely and accurate monitoring of lower extremity venous thrombosis is essential.

[0003] Currently, the main means of monitoring lower extremity venous thrombosis is regular vascular ultrasound examination. This monitoring method relies on large, professional medical equipment and usually needs to be performed in a specific department of the hospital and operated by professional medical staff. Vascular ultrasound examination sends ultrasound into the blood vessels and receives the reflected signals to evaluate the structure and blood flow of the blood vessels, thereby determining whether there is a thrombus.

[0004] However, although vascular ultrasound examination has a certain degree of accuracy in monitoring lower extremity venous thrombosis, most vascular ultrasound examination equipment is bulky and expensive, which limits the portability of vascular ultrasound examination equipment and makes it impossible for patients to monitor at home or other non-medical environments. In addition, because patients can only be examined at the hospital according to the appointment time, the frequency of examination is limited, and it may not be possible to detect small changes or detachment of blood clots in time, and may even delay the best time for treatment. Summary of the invention

[0005] Based on the above problems, the present application provides a flexible CMUT patch and preparation method for monitoring lower extremity venous thrombosis, which can improve the convenience of medical treatment and provide timely warning of the disease to avoid delaying the best treatment time.

[0006] The embodiments of the present application disclose the following technical solutions:

[0007] In a first aspect, the present application discloses a flexible capacitive micromachined ultrasonic transducer CMUT patch for monitoring lower extremity venous thrombosis, wherein the flexible CMUT patch comprises a plurality of flexible CMUT patch units, each of which comprises:

[0008] An acceptor substrate, the acceptor substrate sequentially comprising a flexible substrate, a vibration film, a negative capacitance material layer and a silicon oxide layer, wherein a vacuum cavity is formed on the surface of the silicon oxide layer;

[0009] A donor substrate, the donor substrate comprising an insulating layer and a conductive layer, wherein the conductive layer is connected to the silicon oxide layer;

[0010] a first electrode connected to the insulating layer;

[0011] The second electrode is connected to a side of the flexible substrate away from the vibration film.

[0012] Optionally, the flexible substrate includes a polyimide film or a polydimethylsiloxane film.

[0013] Optionally, the negative capacitance material layer is a hafnium zirconium oxide thin film.

[0014] Optionally, the thickness of the vibration film is 1-3 micrometers, the thickness of the negative capacitance material is 100-500 nanometers, and the thickness of the silicon oxide layer is 500 nanometers.

[0015] Optionally, the vacuum cavity on the surface of the silicon oxide layer is formed by reactive ion etching.

[0016] Optionally, the insulating layer is a silicon oxide layer, and the conductive layer is a silicon layer.

[0017] In a second aspect, the present application discloses a method for preparing a flexible capacitive micromachined ultrasonic transducer CMUT patch for monitoring lower extremity venous thrombosis, the method comprising:

[0018] Generating an acceptor substrate, wherein the acceptor substrate sequentially comprises a flexible substrate, a vibration film, a negative capacitance material layer and a silicon oxide layer, wherein a vacuum cavity is formed on the surface of the silicon oxide layer;

[0019] generating a donor substrate, the donor substrate comprising an insulating layer and a conductive layer, the conductive layer being connected to the silicon oxide layer;

[0020] Connecting the first electrode to the insulating layer, and connecting the second electrode to a side of the flexible substrate away from the vibration film, to obtain a flexible CMUT patch unit;

[0021] A flexible CMUT patch is obtained by combining a plurality of the flexible CMUT patch units.

[0022] Optionally, the generating of the donor substrate, wherein the donor substrate comprises an insulating layer and a conductive layer, wherein the insulating layer is connected to the silicon oxide layer, comprises:

[0023] generating an original donor substrate, wherein the original donor substrate comprises a silicon substrate, an insulating layer and a conductive layer;

[0024] The insulating layer and the silicon oxide layer are connected by wafer bonding, and the silicon substrate is removed by a back thinning process to obtain a donor substrate.

[0025] Optionally, the back thinning process includes any one or more of mechanical thinning, dry etching, wet etching and chemical mechanical polishing.

[0026] Optionally, the flexible substrate includes a polyimide film or a polydimethylsiloxane film.

[0027] Compared with the prior art, this application has the following beneficial effects:

[0028] The present application discloses a flexible CMUT patch and a preparation method for monitoring lower extremity venous thrombosis, wherein the flexible CMUT patch includes a plurality of flexible CMUT patch units, each of which includes a receiving substrate, a donor substrate, a first electrode and a second electrode. The receiving substrate is composed of a flexible substrate, a vibrating film, a negative capacitance material layer and a silicon oxide layer, wherein a vacuum cavity is provided on the surface of the silicon oxide layer to enhance the capacitance response characteristics. The donor substrate includes an insulating layer and a conductive layer, which is connected to the silicon oxide layer of the receiving substrate through the conductive layer to ensure the stability of the electrical connection. The first electrode is connected to the insulating layer of the donor substrate, and the second electrode is located on the outside of the flexible substrate, away from the vibrating film, to form an effective signal acquisition path. Thus, the flexible CMUT patch uses a flexible substrate as part of the receiving substrate, and can adapt to various irregular structures of the surface (such as the human body surface or implanted in the human body). This flexibility not only improves the wearing comfort and ease of use, but also ensures the continuity and accuracy of data collection, which helps to timely warn of changes in the disease and avoid delaying the best treatment time. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0030] Figure 1 A schematic diagram of a flexible CMUT patch unit provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of an acceptor substrate provided in an embodiment of the present application;

[0032] Figure 3 A schematic diagram of a donor substrate provided in an embodiment of the present application;

[0033] Figure 4 A schematic diagram of another flexible CMUT patch unit provided in an embodiment of the present application;

[0034] Figure 5 A schematic diagram of a flexible CMUT patch provided in an embodiment of the present application;

[0035] Figure 6A flow chart of a method for preparing a flexible CMUT patch provided in an embodiment of the present application. DETAILED DESCRIPTION

[0036] First, the technical terms involved in this application are explained:

[0037] Capacitive Micromachined Ultrasonic Transducer (CMUT) is a new type of ultrasonic transducer based on micro-electromechanical system technology. Different from the traditional piezoelectric ultrasonic transducer, CMUT uses capacitance changes to achieve ultrasonic emission and reception. It has the advantages of simple structure, easy integration, wide bandwidth, high sensitivity, etc., and has broad application prospects in medical imaging, industrial detection and other fields.

[0038] As described above, the main means of monitoring lower extremity venous thrombosis is regular vascular ultrasound examination. This examination method relies on large, professional medical equipment and usually needs to be performed in a specific department of the hospital and operated by professional medical staff. Vascular ultrasound examination sends ultrasound into the blood vessels and receives the reflected signals to evaluate the structure and blood flow of the blood vessels, thereby determining whether there is a thrombus.

[0039] However, although vascular ultrasound examination has a certain degree of accuracy in monitoring lower extremity venous thrombosis, most vascular ultrasound examination equipment is bulky and expensive, which limits the portability of vascular ultrasound examination equipment and makes it impossible for patients to monitor at home or other non-medical environments. In addition, because patients can only be examined at the hospital according to the appointment time, the frequency of examination is limited, and it may not be possible to detect small changes or detachment of blood clots in time, and may even delay the best time for treatment.

[0040] After research, the inventor proposed a flexible CMUT patch and preparation method for monitoring lower extremity venous thrombosis, the flexible CMUT patch includes a plurality of flexible CMUT patch units, each of which includes a receiving substrate, a donor substrate, a first electrode and a second electrode. Among them, the receiving substrate is composed of a flexible substrate, a vibrating film, a negative capacitance material layer and a silicon oxide layer, wherein a vacuum cavity is provided on the surface of the silicon oxide layer to enhance the capacitance response characteristics. The donor substrate includes an insulating layer and a conductive layer, which is connected to the silicon oxide layer of the receiving substrate through the conductive layer to ensure the stability of the electrical connection. The first electrode is connected to the insulating layer of the donor substrate, and the second electrode is located on the outside of the flexible substrate, away from the vibrating film, to form an effective signal acquisition path. As a result, the flexible CMUT patch uses a flexible substrate as part of the receiving substrate, which can adapt to various irregular structures of the surface (such as the human body surface or implanted in the human body). This flexibility not only improves the wearing comfort and convenience of use, but also ensures the continuity and accuracy of data collection, which helps to timely warn of changes in the disease and avoid delaying the best treatment time.

[0041] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0042] See also Figure 1 , which is a schematic diagram of a flexible CMUT patch unit provided in an embodiment of the present application. The flexible CMUT patch unit includes: an acceptor substrate 101 , a donor substrate 102 , a first electrode 103 and a second electrode 104 .

[0043] Among them, the acceptor substrate 101 is mainly used to generate ultrasonic waves and receive reflected signals, and the donor substrate 102 is arranged opposite to the acceptor substrate 101, and is mainly used to provide electrical connection and support. The first electrode 103 is connected to the insulating layer of the donor substrate 102, and is responsible for transmitting electrical signals to drive the flexible CMUT patch unit to work or read the signal generated by the flexible CMUT patch unit. The second electrode 104 is connected to the side of the flexible substrate of the acceptor substrate 101 away from the vibrating film, and is mainly used to collect the capacitance change signal caused by the movement of the vibrating film. This design ensures stable signal acquisition even on complex curved surfaces.

[0044] See also Figure 2 , which is a schematic diagram of an acceptor substrate provided in an embodiment of the present application.

[0045] First, a flexible substrate 201 is provided. The flexible substrate 201 is usually made of a material having high flexibility (so that it can be deformed without breaking or losing function when subjected to external force), high mechanical properties (to withstand various mechanical stresses that may be encountered during preparation and use), high insulation properties (to prevent current leakage and short circuit), and high biocompatibility (to ensure the safety and reliability of the flexible CMUT patch when implanted in the human body or in contact with the human body for a long time), such as a polyimide (PI) film, a polydimethylsiloxane (PDMS) film, etc.

[0046] Next, a vibration film 202 , a negative capacitance material layer 203 and a silicon oxide layer 204 are sequentially formed on the flexible substrate 201 .

[0047] When voltage is applied, the vibrating film 202 generates pressure waves, i.e., ultrasonic waves, under the action of electrostatic attraction. Therefore, in order to ensure that the vibrating film 202 can efficiently transmit ultrasonic waves and has good mechanical properties and electrical properties, the following two types of materials are usually selected: metal films and piezoelectric materials. Among them, metal films (such as aluminum, copper, gold, etc.) have the advantages of high conductivity, good mechanical strength and good thermal stability, and piezoelectric materials (such as lead zirconate titanate, barium titanate, etc.) have the advantages of direct electromechanical conversion and high sensitivity. It should be noted that the thickness of the vibrating film 202 is usually around 1-3 microns. This is because a vibrating film 202 that is too thin may not be able to withstand the stress during the manufacturing process or the mechanical load during use; while a vibrating film 202 that is too thick may cause a decrease in response speed and affect the efficiency of ultrasonic generation. A moderate thickness can ensure sufficient mechanical strength to maintain structural integrity without hindering the effective transmission of ultrasonic waves.

[0048] The negative capacitance material layer 203 is responsible for providing a negative capacitance effect (i.e., capacitance decreases as voltage increases) to adjust the vibration frequency and amplitude of the vibrating film 202. The negative capacitance material can be a film material, such as Hf0.5Zr0.5O2 (hafnium zirconium oxide film) etc. It should be noted that the thickness of the negative capacitance material layer 203 is usually around 100-500 nanometers. This thickness range can ensure enough negative capacitance effects, and also can not have too great an impact on the mechanical properties of the vibrating film.

[0049] It can be understood that the beneficial effects of using Hf0.5Zr0.5O2 as the material of the negative capacitance material layer 203 are as follows: First, using Hf0.5Zr0.5O2 as the material of the negative capacitance material layer 203 can improve the sensitivity of the flexible CMUT patch. Hf0.5Zr0.5O2 increases the capacitance change, so that the flexible CMUT patch produces a larger displacement under the same sound pressure, which leads to a more significant change in the capacitance value. This change improves the monitoring capability of weak ultrasonic signals and enhances the resolution and accuracy of ultrasonic imaging.

[0050] Second, using Hf0.5Zr0.5O2 as the material of the negative capacitance material layer 203 can change the equivalent capacitance and inductance of the flexible CMUT patch and optimize its resonance characteristics. This optimization enables the CMUT to achieve efficient acoustic-to-electric conversion in a wider frequency range, improving the resolution and image quality of ultrasonic imaging.

[0051] Third, using Hf0.5Zr0.5O2 as the material of the negative capacitance material layer 203 can enhance the transmission efficiency of the flexible CMUT patch. In the transmitting state, Hf0.5Zr0.5O2 helps to enhance the electric field strength, so that the vibration film 202 obtains a greater driving force, and the flexible CMUT patch can generate a higher intensity ultrasonic signal, thereby improving the transmission power and efficiency.

[0052] Fourth, using Hf0.5Zr0.5O2 as the material of the negative capacitance material layer 203 can enhance and improve the linearity of the flexible CMUT patch. Hf0.5Zr0.5O2 can adjust the capacitance-voltage characteristics of the flexible CMUT patch to make it closer to a linear relationship, reduce nonlinear distortion, and improve the fidelity of the ultrasonic signal.

[0053] Fifth, using Hf0.5Zr0.5O2 as the material of the negative capacitance material layer 203 can reduce the power consumption of the flexible CMUT patch. Since the negative capacitance material improves the performance of the flexible CMUT patch, the demand for external driving voltage or current can be reduced while achieving the same effect, reducing the overall power consumption and extending the use time and endurance of portable or battery-powered devices.

[0054] Sixth, using Hf0.5Zr0.5O2 as the material of the negative capacitance material layer 203 can increase the stability of the flexible CMUT patch. Hf0.5Zr0.5O2 optimizes the internal electric field distribution and mechanical stress state, reduces performance fluctuations caused by factors such as temperature changes and mechanical vibrations, and improves the stability and reliability of the flexible CMUT patch in different working environments.

[0055] In addition, the negative capacitance material Hf0.5Zr0.5O2 is compatible with standard CMOS manufacturing processes and is easy to mass produce. This compatibility reduces the manufacturing cost of the flexible CMUT patch and improves production efficiency.

[0056] The silicon oxide layer 204 is responsible for being used as a protective layer and an insulating layer. As a protective layer, the silicon oxide layer 204 can effectively isolate pollutants (such as dust, moisture, etc.) and corrosive substances (such as acid and alkali solutions) in the external environment, thereby protecting the internal structure from damage. At the same time, the silicon oxide layer 204 can also provide a certain degree of physical protection, reducing the impact of external mechanical stress on sensitive components, such as friction or collision that may be encountered during handling or wearing. As an insulating layer, silicon oxide is an excellent electrical insulator, and its high resistivity can prevent current from flowing through unexpected paths, avoiding unnecessary energy loss and potential safety hazards. It should be noted that the thickness of the silicon oxide layer 204 is usually around 500 nanometers. This thickness range can ensure sufficient protection and insulation performance, and will not have an excessive impact on the overall performance of the flexible CMUT patch.

[0057] It should also be noted that in order to meet the specific needs of the flexible CMUT patch during ultrasonic transmission and reception, a certain number and size of vacuum cavities need to be formed on the surface of the silicon oxide layer 204. The vacuum cavity provides a larger movement space for the vibrating film 202, reduces the damping effect of air or other media on its vibration, and enables the vibrating film 202 to vibrate more freely under the action of the electric field. In addition, a greater degree of vibration freedom means a higher displacement amplitude, which directly improves the responsiveness of the flexible CMUT patch to weak signals and enhances its efficiency in transmitting and receiving ultrasonic waves. Furthermore, precise control of the vacuum cavity can also optimize the resonance characteristics of the flexible CMUT patch, broaden its operating bandwidth, and improve the resolution and image quality of ultrasonic imaging.

[0058] In a specific implementation, the formation of the vacuum cavity is achieved by reactive ion etching (RIE). RIE is an advanced micro-nano processing technology that uses high-energy ion beams to bombard and etch the surface of the material, thereby achieving precise micro-nano structure processing. In the RIE process, the flexible CMUT sample needs to be placed in a vacuum chamber first, and appropriate reaction gases (such as oxygen, hydrogen fluoride, etc.) are introduced. Then, by applying a high-frequency electric field, the reaction gas is ionized to form an ion beam. Under the action of the electric field, these ion beams bombard the surface of the silicon oxide layer 204 at a certain speed and energy. When the ion beam hits the silicon oxide layer 204, physical and chemical dual etching occurs. Physical etching is due to the direct stripping of the material due to the kinetic energy of the ions; chemical etching is due to the chemical reaction between the reaction gas and the material surface to generate volatile products and remove the material. By accurately controlling parameters such as etching time, ion energy, gas type and flow rate, the desired vacuum cavity shape and size can be obtained.

[0059] See also Figure 3, which is a schematic diagram of a donor substrate provided in an embodiment of the present application. The donor substrate 102 includes a Si substrate 301, a silicon oxide layer 302 and a Si layer 303 from bottom to top.

[0060] Among them, the Si substrate 301 provides good mechanical support and electrical properties. The silicon oxide layer 302 is an insulating layer, and its main function is to provide electrical isolation. It prevents the direct flow of current between the Si substrate 301 and the Si layer 303, thereby protecting the electrical structure inside the donor substrate 102 from external interference and avoiding the occurrence of short circuits and other electrical faults. In addition, the silicon oxide layer 302 is also connected to the silicon oxide layer 204 on the acceptor substrate 101 to form a complete insulating interface, which enhances the electrical isolation effect between the two parts and ensures a stable connection between the two. The Si layer 303 is a conductive layer, and the Si layer 303 plays a role in transmitting current or signals in the donor substrate 102. The Si layer 303 can transmit the driving voltage provided by the external circuit to the flexible CMUT patch unit, and is also responsible for receiving and outputting the electrical signal changes generated by the vibrating film 202.

[0061] See also Figure 4 , which is a schematic diagram of another flexible CMUT patch unit provided in an embodiment of the present application. After obtaining the donor substrate 102 and the acceptor substrate 101, the donor substrate 102 is turned upside down (so that its top Si layer is facing the direction of the acceptor substrate 101), and then the acceptor substrate 101 and the inverted donor substrate 102 are connected by wafer bonding. Wafer bonding is a technology that tightly bonds two or more wafer surfaces at a microscopic scale, which can be achieved by a variety of methods, such as direct bonding, anodic bonding, and metal-to-metal diffusion bonding. Among them, direct bonding refers to direct contact with the wafer surface after cleaning and planarization, and atomic-level bonding is achieved under high temperature and high pressure conditions. Anodic bonding refers to the use of high voltage to move ions in insulating materials such as glass to the silicon surface, thereby forming a strong chemical bond. Metal-to-metal diffusion bonding refers to adding a layer of metal (such as gold) between two wafers, promoting diffusion between metal atoms by heating, and finally achieving a strong bond.

[0062] In order to remove the Si substrate of the donor substrate 102 and then form the upper and lower electrodes (i.e., the first electrode 103 and the second electrode 104), a back thinning operation is required. Back thinning refers to a method of removing the Si substrate by any one or more of mechanical thinning (using mechanical tools such as grinding wheels or sandpaper to remove the Si substrate), dry etching (using chemical reactions and physical bombardment in gas or plasma to remove the Si substrate), wet etching (immersing the wafer in a chemical solution to remove the Si substrate through chemical reactions) and chemical mechanical polishing (combining the effects of chemical corrosion and mechanical grinding to remove the Si substrate with higher precision and uniformity). It should be noted that the specific choice depends on factors such as the required precision, uniformity and cost, and this application does not limit the specific back thinning method.

[0063] After the back thinning operation, the original Si substrate 303 is completely removed, exposing the top Si layer 301 of the donor substrate 102, which now forms a complete upper and lower electrode system together with the corresponding structure on the acceptor substrate 101. This design not only simplifies the circuit connection, but also improves the overall performance of the flexible CMUT patch.

[0064] See also Figure 5 , which is a schematic diagram of a flexible CMUT patch provided in an embodiment of the present application. By integrating multiple flexible CMUT patch units, a flexible CMUT array can be obtained. Subsequently, the flexible CMUT array is further integrated with a signal processing unit, a power module, a data storage unit, and a wireless communication module to form a flexible CMUT patch. The following is a detailed description of each component:

[0065] The flexible CMUT array can transmit and receive ultrasound in a wide frequency range, where each flexible CMUT patch unit is responsible for generating ultrasound in a specific frequency range and can capture the reflected ultrasound signal (analog electrical signal), and then send the ultrasound signal to the signal processing unit.

[0066] The signal processing unit includes an amplifier circuit, a filter circuit, an analog-to-digital converter, and a built-in calibration circuit and algorithm. Among them, the amplifier circuit is used to amplify the weak ultrasonic signal obtained by the flexible CMUT array to ensure that the signal strength of the ultrasonic signal is sufficient for subsequent processing. The filter circuit is used to remove noise and interference in the ultrasonic signal and improve the purity and reliability of the ultrasonic signal. The analog-to-digital converter is used to convert the ultrasonic signal (analog electrical signal) into a digital electrical signal to facilitate subsequent digital processing and transmission. The built-in calibration circuit and algorithm are used to compensate, calibrate and compress the digital electrical signal to ensure the authenticity and accuracy of the data. These processing steps include but are not limited to temperature compensation, linearization adjustment, etc., to optimize the data quality of the final output. Subsequently, the processed digital electrical signal is sent to the data storage unit.

[0067] The data storage unit is used to quickly receive and temporarily store or long-term store the processed digital electrical signals transmitted by the signal processing unit. When the doctor end (such as an external medical monitoring system) or the patient end (such as a smart phone, tablet computer) sends a data reception request, the data storage unit will send the processed digital electrical signals to the corresponding terminal device through the wireless communication module.

[0068] The wireless communication module is used to realize two-way data communication between the flexible CMUT patch and external devices. It supports multiple wireless protocols (such as Bluetooth, Wi-Fi, etc.) to ensure that the processed digital electrical signals can be safely and reliably transmitted to the doctor or patient. In addition, since the wireless communication module provides the possibility of remote monitoring, patients can receive continuous health monitoring at home or other non-hospital environments, and doctors can obtain the latest monitoring data in real time to make timely diagnosis and treatment recommendations.

[0069] It is understandable that the flexible CMUT patch is also provided with a power module, which is responsible for converting the input power (such as a battery or external power supply) into a stable voltage suitable for the operation of each internal component to ensure the normal operation of the entire system. Furthermore, the built-in filter circuit of the power module can eliminate noise and fluctuations in the power supply and protect sensitive electronic components from damage; the protection circuit prevents overload, short circuit and other situations from occurring.

[0070] In actual application scenarios, patients can easily attach the flexible CMUT patch to the surface of the skin without the need for a complicated installation process. The flexible CMUT patch transmits and receives ultrasound waves within a wide bandwidth through its built-in flexible CMUT array, enabling it to capture rich physiological information, such as cardiac activity, blood flow, tissue structure, etc. Then, the collected ultrasound signal is amplified, filtered, and analog-to-digital converted by the signal processing unit inside the flexible CMUT patch. Subsequently, the processed digital electrical signal is sent to an external medical monitoring system or the patient's electronic device through a wireless communication module (such as Bluetooth, Wi-Fi, etc.). No matter where the patient is, as long as he is within the network coverage, the doctor can receive the latest data in real time.

[0071] In summary, the present application discloses a flexible CMUT patch, which includes a plurality of flexible CMUT patch units, each of which includes a receiving substrate, a donor substrate, a first electrode and a second electrode. Wherein, the receiving substrate is composed of a flexible substrate, a vibrating film, a negative capacitance material layer and a silicon oxide layer, wherein a vacuum cavity is provided on the surface of the silicon oxide layer to enhance the capacitance response characteristics. The donor substrate includes an insulating layer and a conductive layer, which is connected to the silicon oxide layer of the receiving substrate through the conductive layer to ensure the stability of the electrical connection. The first electrode is connected to the insulating layer of the donor substrate, and the second electrode is located on the outside of the flexible substrate, away from the vibrating film, to form an effective signal acquisition path. As a result, the flexible CMUT patch uses a flexible substrate as part of the receiving substrate, which can adapt to various irregularly structured surfaces (such as human body surface or implanted in the human body). This flexibility not only improves the wearing comfort and ease of use, but also ensures the continuity and accuracy of data collection, which helps to timely warn of changes in the disease and avoid delaying the best treatment time.

[0072] See also Figure 6 , which is a flow chart of a method for preparing a flexible CMUT patch provided in an embodiment of the present application. The method comprises:

[0073] S601: generating an acceptor substrate, wherein the acceptor substrate includes a flexible substrate, a vibration film, a negative capacitance material layer and a silicon oxide layer in sequence, and a vacuum cavity is formed on the surface of the silicon oxide layer.

[0074] In some specific implementations, the flexible substrate includes a polyimide film or a polydimethylsiloxane film.

[0075] In some specific implementations, the negative capacitance material layer is a hafnium zirconium oxide thin film.

[0076] In some specific implementations, the thickness of the vibration film is 1-3 microns, the thickness of the negative capacitance material is 100-500 nanometers, and the thickness of the silicon oxide layer is 500 nanometers.

[0077] In some specific implementations, the vacuum cavity on the surface of the silicon oxide layer is formed by reactive ion etching.

[0078] S602: generating a donor substrate, wherein the donor substrate comprises an insulating layer and a conductive layer, wherein the conductive layer is connected to the silicon oxide layer.

[0079] In some specific implementations, the generating of a donor substrate, wherein the donor substrate comprises an insulating layer and a conductive layer, wherein the insulating layer is connected to the silicon oxide layer, comprises:

[0080] generating an original donor substrate, wherein the original donor substrate comprises a silicon substrate, an insulating layer and a conductive layer;

[0081] The insulating layer and the silicon oxide layer are connected by wafer bonding, and the silicon substrate is removed by a back thinning process to obtain a donor substrate.

[0082] In some specific implementations, the back thinning process includes any one or more of mechanical thinning, dry etching, wet etching, and chemical mechanical polishing.

[0083] In some specific implementations, the insulating layer is a silicon oxide layer, and the conductive layer is a silicon layer.

[0084] S603: Connect the first electrode to the insulating layer, and connect the second electrode to a side of the flexible substrate away from the vibration film, to obtain a flexible CMUT patch unit.

[0085] S604: Combine multiple flexible CMUT patch units to obtain a flexible CMUT patch.

[0086] In summary, the present application discloses a method for preparing a flexible CMUT patch. The flexible CMUT patch produced by this method uses a flexible substrate as a part of the acceptor substrate, which can adapt to surfaces of various irregular structures (such as the surface of the human body or implanted in the human body), thereby enabling long-term, continuous and convenient monitoring, which can not only improve the convenience of medical treatment, but also provide timely warning of the disease to avoid delaying the best treatment time.

[0087] The "first" and "second" in the names such as "first" and "second" (if any) mentioned in the embodiments of the present application are only used as name identifiers and do not represent the first or second in order.

[0088] Through the description of the above implementation methods, it can be known that those skilled in the art can clearly understand that all or part of the steps in the above-mentioned embodiment method can be implemented by means of software plus a general hardware platform. Based on such an understanding, the technical solution of the present application can be embodied in the form of a software product, which can be stored in a storage medium, such as a read-only memory (ROM) / RAM, a magnetic disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network communication device such as a router) to execute the methods described in each embodiment of the present application or some parts of the embodiments.

[0089] It should be noted that each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device and system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiments. The device and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components indicated as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0090] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A flexible capacitive micromachined ultrasonic transducer CMUT patch for monitoring lower extremity venous thrombosis, characterized in that: The flexible CMUT patch includes a plurality of flexible CMUT patch units, each of which includes: An acceptor substrate, the acceptor substrate sequentially comprising a flexible substrate, a vibration film, a negative capacitance material layer and a silicon oxide layer, the negative capacitance material layer being a hafnium zirconium oxide film, the negative capacitance material layer being used to provide a negative capacitance effect to adjust the vibration frequency and vibration amplitude of the vibration film, and a vacuum cavity being formed on the surface of the silicon oxide layer; A donor substrate, the donor substrate comprising an insulating layer and a conductive layer, wherein the conductive layer is connected to the silicon oxide layer; a first electrode connected to the insulating layer; The second electrode is connected to a side of the flexible substrate away from the vibration film.

2. The flexible CMUT patch according to claim 1, characterized in that: The flexible substrate includes a polyimide film or a polydimethylsiloxane film.

3. The flexible CMUT patch according to claim 1, characterized in that: The thickness of the vibration film is 1-3 micrometers, the thickness of the negative capacitance material is 100-500 nanometers, and the thickness of the silicon oxide layer is 500 nanometers.

4. The flexible CMUT patch according to claim 1, characterized in that: The vacuum cavity on the surface of the silicon oxide layer is formed by reactive ion etching.

5. The flexible CMUT patch according to claim 1, characterized in that: The insulating layer is a silicon oxide layer, and the conductive layer is a silicon layer.

6. A method for preparing a flexible capacitive micromachined ultrasonic transducer CMUT patch for monitoring lower extremity venous thrombosis, characterized in that: The method comprises: Generating an acceptor substrate, the acceptor substrate sequentially comprising a flexible substrate, a vibration film, a negative capacitance material layer and a silicon oxide layer, the negative capacitance material layer being a hafnium zirconium oxide film, the negative capacitance material layer being used to provide a negative capacitance effect to adjust the vibration frequency and vibration amplitude of the vibration film, and a vacuum cavity being formed on the surface of the silicon oxide layer; generating a donor substrate, the donor substrate comprising an insulating layer and a conductive layer, the conductive layer being connected to the silicon oxide layer; Connecting the first electrode to the insulating layer, and connecting the second electrode to a side of the flexible substrate away from the vibration film, to obtain a flexible CMUT patch unit; A flexible CMUT patch is obtained by combining a plurality of the flexible CMUT patch units.

7. The method according to claim 6, characterized in that The generating of the donor substrate, wherein the donor substrate comprises an insulating layer and a conductive layer, wherein the insulating layer is connected to the silicon oxide layer, comprises: generating an original donor substrate, wherein the original donor substrate comprises a silicon substrate, an insulating layer and a conductive layer; The insulating layer and the silicon oxide layer are connected by wafer bonding, and the silicon substrate is removed by a back thinning process to obtain a donor substrate.

8. The method according to claim 7, characterized in that The back thinning process includes any one or more of mechanical thinning, dry etching, wet etching and chemical mechanical polishing.

9. The method according to claim 6, characterized in that The flexible substrate includes a polyimide film or a polydimethylsiloxane film.

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