CMUT Medical Devices, Fabrication Methods, Systems, and Related Methods

Abstract

Capacitive Micromachined Ultrasonic Transducer (CMUT) device, manufacturing method, and system, and method of use. The CMUT has a substrate, a peripheral wall defining the boundary of the cavity, and a membrane joined to the peripheral wall. Projecting from the substrate is a post sealed by the peripheral wall. The post contacts but is not joined to the membrane, forming a cavity that resonates at a specific acoustic frequency. The CMUT is disposed within a patient's vascular system in a stent, catheter, or other small device. The CMUT responds to the acoustic frequency emitted from the device outside the body and thereby operates as a sensor for various characteristics of the environment surrounding the CMUT within the body.

Description

Technical Field

[0001] Cross - reference to Related Applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 342,527, titled "CMUT DEVICE AND FABRICATION METHOD," filed on May 16, 2022, and U.S. Provisional Patent Application No. 63 / 342,812, titled "MEDICAL DEVICES, SYSTEMS AND RELATED METHODS," filed on May 17, 2022, both of which are incorporated herein by reference in their entirety.

[0002]

[0002] The present invention generally relates to medical devices incorporating sensors and electronic devices. In one non - limiting example, such medical devices can include intravascular devices such as guidewires and catheters, and such devices can include various sensors for imaging and / or measuring one or more physiological parameters. In other non - limiting examples, the medical device can include implantable sensors for providing imaging, monitoring, or measurement of physiological parameters.

Background Art

[0003]

[0003] Among these medical devices is the capacitive micromachined ultrasonic transducer (CMUT), which is a relatively new technology in the field of transducers. In many applications, CMUTs can be used for ultrasonic generation and / or ultrasonic reception. Because of their small size, CMUTs offer unique benefits in medical devices that require tight tolerances and small sensors. Fabrication of such devices can be very difficult considering issues such as performance, yield, reliability, and cost.

Summary of the Invention

Problems to be Solved by the Invention

[0004]

[0004] There is a need for improved medical devices that can substantially integrate sensors to provide data more efficiently and / or to provide data that heretofore could not practically be obtained.

[0005]

[0005] The subject matter claimed herein is not limited to embodiments that solve the above disadvantages or that operate only in the above-described environments. Rather, this background is provided only to illustrate one exemplary technical field in which some embodiments described herein can be implemented.

Means for Solving the Problems

[0006]

[0006] At least one embodiment disclosed herein includes a capacitive micromachined ultrasonic transducer (CMUT) device comprising a substrate that can include a CMOS (complementary metal oxide semiconductor) wafer, the CMUT device having one or more sidewalls protruding from the substrate. The one or more sidewalls define an outer boundary of a cavity. Additionally, a silicon-on-insulator (SOI) wafer having a highly doped silicon layer thereon can be bonded to the one or more sidewalls such that the cavity is positioned between the SOI and the substrate. A membrane positioned at a side of the cavity can be formed when removing a handling wafer from the SOI wafer.

[0007]

[0007] The CMUT can also include one or more posts protruding from the substrate. The one or more posts can be enclosed by the one or more sidewalls. At least a portion of the one or more posts includes a width of less than 10 microns. Additionally, one or more inner walls can protrude from the substrate. The one or more inner walls can be enclosed by the one or more sidewalls.

[0008] In addition, at least one embodiment can include a capacitive micromachined ultrasonic transducer (CMUT) device. The device includes a substrate, one or more sidewalls protruding from the substrate that define an outer boundary of a cavity, and a membrane bonded to the one or more sidewalls, where the cavity is positioned between the membrane and the substrate. The device also includes one or more posts protruding from the substrate, where the one or more posts are sealed by the one or more sidewalls and at least a portion of the one or more posts includes a width of less than 10 microns. The device also has one or more inner walls protruding from the substrate, where the one or more inner walls are sealed by the one or more sidewalls.

[0009] Further embodiments of the present disclosure are directed to a method for constructing a capacitive micromachined ultrasonic transducer (CMUT). The method includes placing one or more sidewalls on a substrate, where the one or more sidewalls define an outer boundary of a cavity and the one or more sidewalls include a width of at least 8 microns. The method then includes placing one or more posts on the substrate, where the one or more posts are sealed by the one or more sidewalls and at least a portion of the one or more posts includes a width of from 1 micron to 10 microns. The method also includes placing, on the substrate, one or more inner walls protruding from the substrate, where the one or more inner walls are sealed by the one or more sidewalls and at least a portion of the one or more inner walls includes a width of from 0.5 micron to 1 micron.

[0010] Further embodiments of the present disclosure are directed to a medical device having a body and at least one electronic component associated with the body. The at least one electronic component includes at least one sensor and an ultrasonic transducer configured to receive an ultrasonic signal and thereby power the at least one sensor. The electronic component is configured to provide a response ultrasonic wave in response to a determination by the at least one sensor.

[0011]

[0011] A further embodiment of the present disclosure is directed to a system including an external device having a first ultrasonic transducer and a medical device configured to be positioned within a patient's anatomical structure. The medical device includes at least one electronic component, at least one sensor, and a second ultrasonic transducer configured to receive an ultrasonic signal generated by the first ultrasonic transducer and power the at least one sensor. The electronic component is configured to provide a response ultrasonic wave to the external device in response to a determination by the at least one sensor.

[0012]

[0012] Further, another embodiment of the present disclosure is directed to a method including implanting an electronic component within a patient, adjacent to, or within a tumor, powering the electronic component using ultrasonic energy, and detecting moisture of the tumor using a sensor of the electronic component. The method also includes providing a response signal from the electronic component to an external device based on the detected moisture and determining a density of the tumor or a change in the density of the tumor based on the response signal.

[0013]

[0013] Another embodiment of the present disclosure is directed to a medical device including a flexible elongate member having a distal portion configured to be inserted into a patient's blood vessel and an imaging device disposed within the distal portion of the elongate member. The imaging device includes a flexible substrate, a plurality of ultrasonic transducers disposed on the flexible substrate, each of the plurality of ultrasonic transducers comprising a capacitive micromachined ultrasonic transducer (CMUT on CMOS) device on a complementary metal oxide semiconductor, and a tail extending from the flexible substrate and having a plurality of connection pads.

[0014]

[0014] This summary is provided to introduce briefly a series of concepts that will be further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0015]

[0015] Additional features and advantages will be described in the following description, some of which will be apparent from the description or can be learned by practicing the teachings herein. The features and advantages of the invention can be realized and obtained by the means and combinations particularly pointed out in the appended claims. The features of the invention will become more fully apparent from the following description and appended claims, or can be learned by practicing the invention as described below.

[0016]

[0016] To explain how the above additional advantages and features can be obtained, a more specific description of the subject matter briefly described above is provided by referring to the specific embodiments illustrated in the accompanying drawings. It should be understood that these drawings show only typical embodiments and should not be considered as limiting the scope. With respect to the embodiments, the following accompanying drawings will be used to explain and clarify with additional specificity and detail.

Brief Description of the Drawings

[0017]

Figure 1

[0017] A side view of a silicon-on-insulator (SOI) wafer according to an embodiment of the present disclosure.

Figure 2

[0018] A side view of a complementary metal-oxide-semiconductor (CMOS) wafer having a lower electrode according to an embodiment of the present disclosure.

Figure 3

[0019] A side view of a CMOS wafer cavity having an oxide layer according to an embodiment of the present disclosure.

Figure 4

[0020] A side view of CMOS wafer bonding according to an embodiment of the present disclosure.

Figure 5

[0021] A side view of a CMUT according to an embodiment of the present disclosure.

Figure 6

[0022] A top view of a CMOS wafer in a film according to an embodiment of the present disclosure.

Figure 7

[0023] A flowchart of steps in a method for fabricating a CMUT according to an embodiment of the present disclosure.

Figure 8

[0024] A diagram showing a catheter according to an embodiment of the present disclosure.

Figure 9

[0025] An enlarged view of a portion of the catheter shown in FIG. 8.

Figure 10

[0026] A cross-sectional view taken along line 10-10 shown in FIG. 9.

Figure 11

[0027] A diagram showing a sensor array that can be used within the catheter shown in FIG. 8.

Figure 12

[0028] A diagram showing a stent according to an embodiment of the present disclosure.

Figure 13

[0029] A diagram showing a system according to an embodiment of the present disclosure.

Figure 14

Figure 15

[0030] A diagram showing another system according to an embodiment of the present disclosure.

Figure 16

[0031] A diagram showing a transaortic valve according to an embodiment of the present disclosure.

Figure 17

[0032] A diagram showing another system according to an embodiment of the present disclosure.

Figure 18

[0033] A diagram showing a wearable patch according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

[0018]

[0034] The present disclosure provides various examples and embodiments of medical devices, systems, methods, and related components. Such devices, systems, etc. can be used in the diagnosis and / or treatment of a health condition, including the detection or determination of desired parameters or characteristics. The disclosed embodiments include capacitive micromachined ultrasonic transducers (CMUTs). In some embodiments, the CMUT can be used within a medical device. For example, the disclosed CMUT can be used within implantable sensors, intravascular ultrasound (IVUS) catheters, ultrasonic imaging devices, and / or other medical devices that utilize transducers. The transducer can be used for inducing and / or receiving ultrasonic signals.

[0019]

[0035] Conventional CMUTs include a top electrode integrated within a membrane, a bottom substrate, and a cavity formed between the membrane and the substrate. When a force is applied to the conductive membrane, the membrane deforms. The deformation of the membrane results in a variation in the capacitance between the membrane and the substrate. The resulting change in the electric field can be detected and / or generated by a circuit integrated within the CMUT. Conversely, when an electrical signal is applied to the substrate (e.g., the electrode under the membrane), the membrane deforms, and as a result, acoustic waves are generated by the vibrating membrane. Conversely, a change in the capacitance between the membrane and the substrate results in membrane displacement, which can result in ultrasonic waves.

[0020]

[0036] Fabrication of the CMUT can be performed by a variety of different methods, including the use of sacrificial layers, initial cavities, final cavities, surface micromachining, or any number of different fabrication methods. In at least one embodiment, the disclosed CMUT is fabricated using thermal oxide growth on a silicon-on-insulator (SOI) wafer. FIG. 1 shows a side view of a silicon-on-insulator (SOI) wafer 100. The SOI wafer can include a handle wafer 110, a buried oxide (BOX) layer 120, and a membrane layer 130. In one exemplary embodiment, fabrication of the CMUT is 1.0 μm ± 0.3 μm, N++ red phosphorus doping, 0.1 - 0.2 Ω / cm 2It can include a parameter such as this. Thermal oxide film growth can include, for example, 0.0001 μm (1 Å (angstrom)) to 0.04 μm (400 Å) in a dry state at 980 °C.

[0021]

[0037] Figure 2 shows a side view of a complementary metal oxide semiconductor (CMOS) wafer 200 having a lower electrode 210 on a substrate 220. The substrate can be formed from silicon, among other things, and can include various circuits such as a signal generation circuit and a signal reception circuit. In at least one embodiment, the CMOS wafer 200 is fabricated using parameters of UTM M8 (3 μm, Cu) on CMOS with 1.5 μm of oxide film passivation by SiN as a gas release barrier. Vias can be added by a Cu damascene process, and the bottom electrode can also be fabricated up to 1000 Å using the same Cu damascene process.

[0022]

[0038] Figure 3 shows a side view of a CMOS wafer in which at least one cavity 300 is formed within an oxide film layer. At this time, the CMOS wafer can include a peripheral wall 310 that defines the cavity 300 and one or more posts 320 positioned within the cavity 300. In one exemplary embodiment, the CMOS wafer cavity can be constructed using parameters of 400 Å of CVD (chemical vapor deposition) oxide film / 450 Å of SiN, 6 - 8 K of HDP → CMP to SiN, peripheral wall and post etch stopped with SiOx, and 200 Å of HDP oxide film.

[0023]

[0039] FIG. 4 shows a side view of a CMOS wafer bond 400. In the illustrated embodiment, the SOI wafer 100 of FIG. 1 is bonded to a CMOS wafer having at least one cavity 300 from FIG. 3. At this time, the film 130 is positioned over the cavity. Fabrication can include a cleaning process such as an EKC® cleaning process, plasma activation and low temperature bonding, as well as post-bond annealing at 300° C. for 90 minutes. In at least one embodiment, the bonding temperature can be from about 400° C. to about 425° C. over 30 minutes or less. Additionally or alternatively, the bonding temperature can include a temperature less than 400° C. As a result of the low temperature bonding, the film 130 is bonded to the sidewall 310, but in at least some embodiments is not bonded to one or more (or all) of the posts 320.

[0024]

[0040] FIG. 5 shows a side view of the CMUT 500 after metallization and passivation. The resulting CMUT 500 at this time includes one or more vias 510, one or more cells 540, and a trench etch 520 for separating the conductive film 130 from the conductive circuit integrated with the CMUT. The fabrication process can include a wafer grinding and etching process. Etching can be used to open the contacts 550. Additionally, the fabrication process can include a metal grid, metal deposition for Ti / 1.5 μm of Al / Ti / 1.5 μm of Al, BOX removal and thinning etch on the film 130, and a trench etch. Further, fabrication can include the deposition of a passivation layer (e.g., having parameters of 0.5 μm of SiO2 / 0.5 μm of SiN) and pad opening.

[0025]

[0041] FIG. 6 shows, without the film, a top view 600 of a CMOS wafer. The CMOS wafer shown includes a top view showing a peripheral wall 310 that circumscribes and defines cavity 300 and one or more posts 320 positioned within cavity 300. Also shown are one or more inner walls 610 protruding from substrate 220. Inner walls 610 are positioned within the boundaries of peripheral wall 310 and can be positioned between adjacent posts 320. As shown, in at least one embodiment, posts 320 and inner walls 610 serve to define individual cells 540 arranged in an array within cavity 300. In the embodiments shown in FIGS. 5 and 6, the disclosed cavities exhibit a square shape. Further, in at least one embodiment, cells 540 are in fluid communication with each other, and thus a given cell 540 is not completely physically separated from its adjacent cell 540, but instead is fluidly open to its vicinity. Individual cells 540 function as individual transducers, and each cell has its own individual addressable electrode 530.

[0026]

[0042] In at least one embodiment, the acoustic performance of a CMUT can be specified by controlling the location and size of one or more posts 320 and one or more inner walls 610. Additionally, the size and shape of a given cell 540 or set of cells 540 need not be the same as those in its vicinity. Thus, the cells 540 shown in FIG. 6 can be made of different shapes and sizes so as to be tuned to various different characteristic acoustic frequencies. Additionally, those of relatively small size among one or more posts 320 and one or more inner walls 610 can enable larger electrodes 530 (shown in FIG. 5), thereby increasing the sensitivity and performance of the CMUT.

[0027]

[0043] Accordingly, the disclosed CMUT can include a substrate 220 from which one or more sidewalls 310 protrude. As can be seen more clearly in FIG. 6, the one or more sidewalls 310 define the outer boundary of the cavity 300. A membrane 130 is joined to the one or more sidewalls 310. As shown in FIG. 5, the cavity 300 is positioned between the membrane 130 and the substrate 220. One or more posts 320 protrude from the substrate 220. The one or more posts 320 are enclosed by the one or more sidewalls 310.

[0028]

[0044] As used herein, the “width” of an object is measured in the x - direction or z - direction as shown with respect to FIGS. 5 and 6, and thus the width is the lateral scale of the CMUT feature. In contrast, the “height” or “thickness” is measured in the y - direction as shown with respect to FIG. 5, and thus the height or thickness is the vertical scale of the CMUT feature. In particular, unless otherwise stated, the thickness or height is the vertical scale of the feature extending from the cavity floor to the top of the feature.

[0029]

[0045] In at least one embodiment, the sidewall 310 includes a width of at least 8 microns, at least 10 microns, or at least 12 microns. Additionally, or alternatively, in at least one embodiment, at least a portion of the one or more posts 320 includes a maximum cross - sectional width of less than 10 microns, less than 8 microns, or less than 5 microns. Further, in at least one embodiment, the inner wall 610 includes a width (e.g., lateral scale) of less than 10 microns, less than 8 microns, or less than 5 microns.

[0030]

[0046] During the bonding process in fabrication, the film 130 conventionally requires a minimum surface area to physically bond to a wall or post. In some embodiments, the minimum surface area can include a wall (e.g., a peripheral wall) having a width of at least 10 microns, or a wall having a width greater than at least 8 microns. Similarly, for physically bonding to a post during the bonding process in fabrication, the minimum area of the post can include a post having an upper surface area with a dimension of at least 10 microns (e.g., a square post with dimensions of at least 10 microns × 10 microns, or a post having a diameter of at least 10 microns), or a post having an upper surface area with a dimension of at least 8 microns (e.g., a square post with dimensions of at least 8 microns × 8 microns, or a post presenting a diameter of at least 8 microns). Thus, in some embodiments, by fabricating one or more peripheral walls 310 having a width of at least 8 microns, preferably at least 10 microns, the film can be physically bonded to the one or more peripheral walls 310. In contrast, in some embodiments, by fabricating one or more posts 320 having a cross-sectional width of less than 10 microns, preferably less than 8 microns, the film remains unphysically bonded to the one or more peripheral walls 310 during the fabrication bonding process. Similarly, in some embodiments, by fabricating one or more inner walls 610 having a width of less than 10 microns, preferably less than 8 microns, more preferably less than 1 micron, the film remains unphysically bonded to the one or more inner walls 610 during the fabrication bonding process.

[0031]

[0047] In at least one embodiment, the membrane 130 is not joined to at least a portion of one or more posts 320. Additionally, or alternatively, in at least one embodiment, the membrane 130 is not joined to at least a portion of one or more inner walls 610. The one or more posts 320 and / or the one or more inner walls 610 can include, for example, a height that is 2 nanometers shorter than the height of the peripheral wall 310 (i.e., in the direction of the paper for the CMUT shown in FIG. 6). In other embodiments, the height of the one or more posts 320 and the one or more inner walls 610 can be 1 micron shorter, 0.5 micron shorter, or at least 2 nanometers shorter than the height of the peripheral wall 310, or can be any range including the foregoing values as endpoints. Thus, the membrane 130 can be configured to join to the peripheral wall 310, but remains unjoined to at least a portion of the one or more posts 320 and the one or more inner walls 610. In some embodiments, the membrane 130 is not joined to any of the one or more posts 320. In an alternative embodiment, the membrane 130 is not joined to a majority of the one or more posts 320.

[0032]

[0048] In at least one embodiment, by utilizing one or more posts 320 and / or one or more inner walls 610 of a relatively small size (i.e., too small to physically join to the membrane), the resulting CMUT provides a larger active area of the membrane 130. Additionally, in the disclosed fabrication embodiments, since the area requiring physical joining is relatively small, more reliable CMUT fabrication is possible. In particular, since only one or more peripheral walls 310 require joining, there is a lower likelihood of creating defects that can occur compared to conventional joining processes that may require joining in one or more peripheral walls 310, one or more posts 320, and one or more inner walls 610.

[0033]

[0049] In at least one embodiment, cavity 300 includes a negative air pressure relative to the outside of CMUT 500. During fabrication, vents can be opened to the CMUT (e.g., through the peripheral wall 310). A vacuum can be applied to the vents to generate a negative air pressure within cavity 300. The resulting pressure differential can press membrane 130 against one or more posts 320 and / or one or more inner walls 610, supporting or reinforcing membrane 130 at individual locations (e.g., similar to the "posts of a tent"). In at least one embodiment, by creating cells 540 that are in fluid communication with each other, the initial internal pressure within the CMUT is also distributed across the device. For example, in a conventional CMUT, cavities at the corners of the device can contain an internal pressure of up to 10 atmospheres. This high pressure can cause the CMUT bonds to fail before the device is depressurized. In contrast, in the disclosed embodiments, cells 540 are left in fluid communication with each other, and thus the pressure can spread across the device. As a result, the pressure per cell is reduced, the likelihood of bond failure before venting the device is reduced, and the venting of cavity 300 is simplified.

[0034]

[0050] The use of "bonded" and "unbonded" herein is to be understood by those skilled in the art to refer to the state of membrane 130 relative to one or more peripheral walls 310, one or more posts 320, and one or more inner walls 610 during fabrication. In practice, after fabrication, after a charge is applied to membrane 130, and / or after the membrane is pressed against one or more posts 320 and one or more inner walls 610 by the negative pressure within cavity 300, ultimately, a relatively weak but bond-forming can be formed between membrane 130 and at least a portion of one or more posts 320 and one or more inner walls 610 for the available area.

[0035]

[0051] Next, the following discussion refers to ways and method operations that can be performed. Regarding method operations, they may be discussed in a particular order or shown in a flowchart as being performed in a particular order, but a particular order is not required unless specifically stated or required because an operation depends on another operation that is completed before the operation is performed.

[0036]

[0052] FIG. 7 shows a flowchart of steps in a method 700 for fabricating a CMUT. The method shown includes an operation 710 of disposing or forming a peripheral wall 310 on a substrate. Operation 710 includes the step of disposing or forming one or more peripheral walls 310 on the substrate, where the one or more peripheral walls 310 define an outer boundary of a cavity and the one or more peripheral walls 310 include a width of at least 8 microns (the width is defined as described above with respect to FIG. 6). The one or more peripheral walls can be formed using additive or subtractive processes.

[0037]

[0053] Method 700 can also include an operation 720 of disposing or forming posts on the substrate. Operation 720 includes the step of disposing one or more posts on the substrate, where the one or more posts 320 are laterally enclosed by the one or more peripheral walls 310 and at least a portion of the one or more posts 320 includes a width of 1 micron to 10 microns. Additionally, method 700 can include an operation 730 of disposing or forming an inner wall 610 on the substrate. Operation 730 includes the step of disposing or forming one or more walls protruding from the substrate on the substrate, where the one or more walls are laterally enclosed by the one or more peripheral walls and at least a portion of the one or more walls includes a width of 0.5 micron to 1 micron. The posts and / or walls can be formed using additive or subtractive processes.

[0038]

[0054] In an additional embodiment, method 700 can further include joining membrane 130 to one or more peripheral walls 310 such that cavity 300 is positioned between membrane 130 and the substrate. The step of joining membrane 130 to one or more peripheral walls 310 can be accomplished while leaving at least a portion of one or more posts 320 and / or one or more inner walls 610 unjoined to membrane 130. The method can further include creating a negative relative pressure within the cavity by venting or bleeding gas from cavity 300 and contacting the membrane with at least some of the posts and / or inner walls.

[0039]

[0055] Referring to FIG. 8, catheter 800 is shown. Although the catheter is presented as an example with respect to FIG. 8 (and related FIGS. 9-11), the components, features, and embodiments described can also apply to the structure of a guidewire or other elongated flexible element. Catheter 800 includes an elongated flexible body 802 (also referred to herein as an "elongated flexible member") and can be associated with a proximal device 804. In some embodiments, proximal device 804 can include, for example, a control unit (not shown) and / or a valve device as described in U.S. Patent No. 11,304,659, entitled "OPERATIVELY COUPLED DATA AND POWER TRANSFER DEVICE FOR MEDICAL GUIDEWIRES AND CATHETERS WITH SENSORS," issued on April 19, 2022, or U.S. Patent Application No. 17 / 979,629, entitled "DATA AND POWER TRANSFER DEVICES FOR USE WITH MEDICAL DEVICES AND RELATED METHODS," filed on November 2, 2022, the disclosures of which are hereby incorporated by reference in their entirety.

[0040]

[0056] The catheter 800 includes one or more sensors 806. Power wires and / or data lines 808 can extend along the length of the catheter 800 to one or more sensors 806 near the distal end 810 of the elongate body 802. As used herein, "power line" and / or "data line" refers to any conductive path (e.g., trace) within or on a medical device. Multiple power and / or data lines can be utilized, although some embodiments can be configured to transmit both power and data on a single line and / or manage sensor data signals from multiple sensors on a single line. This reduces the number of lines that must be routed through the structure of the catheter 800, more effectively utilizes the limited space of the device, and reduces the complexity of the device and the risk of associated device failures.

[0041]

[0057] The proximal device 804 can include one or more ports to facilitate the introduction of fluid (e.g., drugs, nutrients, nanoparticle colloidal solutions) into the catheter 800. The body 882 or at least its distal portion can be sized and configured to be temporarily inserted into the body and can be configured, for example, to provide diagnostic information or deliver a graft into the body. In one embodiment, the catheter 800 is a peripherally inserted central catheter (PICC) line and is typically placed within the arm or leg of the body to access the body's vasculature. The catheter 800 can also be a microcatheter, central venous catheter, IV catheter, coronary catheter, stent delivery catheter, balloon catheter, atherectomy catheter, or an IVUS catheter, or other imaging catheter. The catheter 800 can be a single or multi-lumen catheter.

[0042]

[0058] Referring to FIG. 9, one or more sensors 806 of the catheter 800 can include, for example, a pressure sensor, a flow sensor, an imaging sensor, a component detection sensor, or a combination thereof. In addition, although generally referred to as "sensors" when discussing various embodiments throughout this specification, such "sensor" components (e.g., sensor 906) can comprise, be associated with in other ways, or be configured as input devices, output devices, or both, and can include transducers or other components.

[0043]

[0059] As shown in FIGS. 9 and 10, the sensors 806 are circumferentially arranged around the longitudinal axis 812 of the elongated body 802. In the embodiment shown in FIG. 9, the sensor 806 includes an ultrasonic transducer that can be used for imaging (e.g., imaging of blood vessels), activation or release of a therapeutic agent, or some other purpose. In one embodiment, the ultrasonic transducer can include a capacitive micromachined ultrasonic transducer (CMUT) as described above in this specification. In other embodiments, the ultrasonic transducer can include a piezoelectric transducer, including a piezoelectric micromachined ultrasonic transducer (PMUT) or some other type of ultrasonic device.

[0044]

[0060] Although FIGS. 9 and 10 show eight separate transducers / sensors 806 circumferentially arranged around the longitudinal axis 812 of the body 802, other numbers of sensors 806 can be used and other geometric and spatial arrangements can be utilized. Thus, the catheter 800 can be utilized as a side-viewing intravascular ultrasound (IVUS) catheter for imaging blood vessels (e.g., coronary blood vessels) when determining, for example, whether a stenosis or some other condition is present and whether a particular intervention can be permitted, as shown in FIGS. 1 - 3.

[0045]

[0061] Referring briefly to FIG. 11, a CMUT array 830 is shown, and using the CMUT array 830, an array of circumferentially arranged sensors 806 can be formed within the catheter 800 or within any other device where an array CMUT or other sensors are desired, as shown in FIGS. 9 and 10. The array 830 includes a flexible substrate 832 and a plurality of sensors / CMUTs 806. In one embodiment, the flexible substrate can include a polyimide material. In one embodiment, the sensors / CMUTs 806 can be disposed on the flexible substrate 832, and in other embodiments, the sensors / CMUTs 806 can be sandwiched between multiple layers of flexible material or otherwise encapsulated by the flexible material. A flexible tail 834 can be integrally formed with the flexible substrate 832, and the tail 834 extends from the sensors / CMUTs 806 and can provide a plurality of connection pads 836 for connection to other electronic devices (e.g., another flexible circuit, a ribbon cable, individual conductors, etc.). Circuits can be formed within the substrate 832 / tail 834 to connect the individual sensors / CMUTs 806 together, to connect the sensors / CMUTs 806 to the connection pads 836, and / or to connect other electronic components associated with the CMUT array 830.

[0046]

[0062] When implemented within a catheter or other elongated body, the CMUT array 830 can be "rolled up" in a configuration as shown in FIGS. 9 and 10, and the connection pads 836 can be coupled to power / data lines (e.g., line 808 shown in FIG. 15). Again, although a single row of eight sensors / CMUTs 806 is shown, the CMUT array 830 can assume other configurations, including different numbers of sensors / CMUTs 806, multiple rows of sensors / CMUTs, alternating spatial arrangements of sensors / CMUTs 806, etc. Additionally, in some embodiments, the CMUT array 830 can include CMUTs of different specifications, including at least two CMUTs configured to operate at different frequencies.

[0047]

[0063] Referring to FIG. 12, a medical device in the form of a stent 900 according to one embodiment of the present disclosure is shown. The stent can include a body 902 positioned within a blood vessel 904 to act as a scaffold or support structure at a desired location within the blood vessel 904 (e.g., within a calcified portion of a coronary artery). As will be understood by those skilled in the art, the stent 900 can be delivered by a catheter, which is initially in a radially collapsed state and then radially expanded at a desired location to expand the blood vessel and open the lumen of the blood vessel to increase fluid flow. One or more electronic components 906 (e.g., sensors, system-on-chip (SOC) as described above herein) can be coupled to, embedded within, or otherwise associated with the stent 900. For example, in one embodiment, the electronic component can include an ultrasonic transducer (e.g., a CMUT chip as discussed above) along with some other type of sensor (e.g., a pressure sensor, a flow sensor, a proximity sensor that can be separate from or integrated with the CMUT chip). The electronic component 906 can be "passive" in the sense that it is not powered or actively sensing or processing unless positively activated by a specific external stimulus. In the embodiment shown in FIG. 12, there are two separate electronic components 906, each disposed near a respective longitudinal end of the stent 900 (e.g., one is located distally and one is located proximally).

[0048]

[0064] As shown in FIGS. 6 and 7, the stent 900 can be used as part of the system 910, and the patch or pad 912 is disposed on the outer surface 914 of the user's tissue 916. As discussed in more detail below, the patch 912 can include one or more ultrasonic transducers 918 configured to emit ultrasonic waves 920 (also referred to as sound waves) at one or more desired frequencies into the tissue 916 up to the electronic component 906. Optionally, the wave 822 can be focused by beamforming or other known techniques such that the energy from the sound wave 920 is focused at a desired location (e.g., the location of the electronic component 906). As shown in FIG. 13, ultrasonic waves can be transmitted to the electronic component 906, and the energy from the sound wave 920 can be used to power the electronic component 906 by receiving the ultrasonic waves by an ultrasonic transducer (e.g., CMUT) associated with the electronic component 906.

[0049]

[0065] When powered, the electronic component 906 can operate to perform a desired function according to a desired protocol. For example, the electronic component 906 can include sensors for detecting parameters related to the health and function of the blood vessel 904 and / or the situation or state of the stent 900. In one embodiment, the electronic component 906 can include a pressure sensor and can measure the fluid pressure to determine whether there is a significant occlusion (e.g., re-calcification) in the blood vessel at the location of the stent 900. For example, the pressure can be measured at each end of the stent to determine whether a pressure drop has occurred that exceeds a predetermined threshold. If a pressure drop occurs that exceeds an acceptable value, an intervention may be required. However, the determination of whether an intervention is required can be made at least preliminarily without using additional invasive techniques. In other embodiments, other parameters such as flow rate, temperature, or other information related to the diagnosis of the health of the blood vessel can also be determined by the sensors.

[0050]

[0066] Referring to FIG. 14, after a related sensor determines a specified parameter or characteristic, an ultrasonic signal (referred to herein as the "response signal 930" to distinguish it from the initially transmitted ultrasonic signal 920) can be transmitted from the electronic component 906 to the patch 912. This can occur in a variety of different ways. In one example, the electronic component 906 processes the information obtained by the accompanying sensor and then can transmit the response signal 930 to the patch 912 again by the accompanying transducer (e.g., CMUT).

[0051]

[0067] In another embodiment, when a sensor associated with the electronic component 906 detects a specific parameter state (e.g., pressure above a specified threshold), a membrane, disk, magnetic device, or some other component can be changed to reflect the transmitted sound wave 920 (FIG. 13) in a specified way, generating a response wave 930. The system associated with the patch 910 recognizes this response signal and indicates that a specific parameter state has been detected. Such a system requires relatively little power and can significantly reduce the size of the electronic components.

[0052]

[0068] Referring further to FIGS. 6 and 7, in another embodiment, the electronic component 906 can include a proximity sensor, or the system 910 can include additional processors or sensors to determine the relative location of each (or a selected portion) of the electronic components 906. Thus, for example, based on the relative location of two or more electronic components 906, it can be determined whether the body 902 of the stent 902 is fully expanded (e.g., the stent body 902 may contract (or shorten) longitudinally as it expands radially, thereby changing the position of the electronic components 906 relative to each other).

[0053]

[0069] The electronic component 906 (in the above example and other embodiments) can include sensors to detect various other parameters or characteristics related to an individual's health status or the performance of a medical device implanted in the individual. For example, the electronic component 906 can include sensors configured to sense the presence of biological components or measure physiological parameters at a targeted anatomical location. Exemplary biological components and physiological parameters that can be detected / measured include blood glucose level, pH level, CO2 concentration (partial pressure of CO2, bicarbonate concentration), oxygen concentration (partial pressure of oxygen, oxygen saturation), pressure, temperature, and other such substrates and physiological parameters. One or more sensors can be configured to sense the presence, absence, or level of biological components such as immune system-related molecules (e.g., macrophages, lymphocytes, T cells, natural killer cells, monocytes, other white blood cells, etc.), inflammatory markers (e.g., C-reactive protein, procalcitonin, amyloid A, cytokines, α1-acid glycoprotein, ceruloplasmin, hepcidin, haptoglobin, etc.), platelets, hemoglobin, ammonia, creatinine, bilirubin, homocysteine, albumin, lactate, pyruvate, ketone bodies, ions and / or nutrient levels (e.g., glucose, urea, chloride, sodium, potassium, calcium, iron / ferritin, copper, zinc, magnesium, vitamins, etc.), hormones (e.g., estradiol, follicle-stimulating hormone, aldosterone, progesterone, luteinizing hormone, testosterone, thyroxine, thyrotropin, parathyroid hormone, insulin, glucagon, cortisol, prolactin, etc.), enzymes (e.g., amylase, lactate dehydrogenase, lipase, creatine kinase), lipids (e.g., triglycerides, HDL cholesterol, LDL cholesterol), tumor markers (e.g., alpha-fetoprotein, beta-human chorionic gonadotropin, carcinoembryonic antigen, prostate-specific antigen, calcitonin), toxins (e.g., lead, ethanol), and / or the number of white blood cells or red blood cells (e.g., using a microfluidic chamber), etc.Additionally, or alternatively, a sensor can be used to detect evidence of thrombosis, impedance of tissue structure (or implanted medical device), moisture (e.g., to detect changes in tumor density or size), or physical size of a desired anatomical structure (e.g., based on proximity of implanted electronic components).

[0054]

[0070] Referring briefly to FIG. 15, another system 940 according to another embodiment of the present disclosure is shown. System 940 includes a stent 900 having electronic components 906 as described above, but instead of using a patch attached to or otherwise disposed on the patient's skin, a handheld (e.g., portable) ultrasonic probe 942 is used. Probe 942 includes one or more ultrasonic transducers 918 to power the electronic components 906 and / or provide energy to communicate with the electronic components 906, as described above. Probe 940 can be associated with other systems and hardware or can be a stand-alone device.

[0055]

[0071] Referring briefly to FIG. 16, a human heart 1000 in which a transcatheter aortic valve replacement (TAVR) procedure is being performed is shown, with a new valve 1002 disposed within the native diseased aortic valve. The new valve 1002 can include one or more electronic components 906 as described above with respect to stent embodiments. The electronic components 906 can be used as part of a system as described hereinabove (e.g., using a patch or ultrasonic probe). For example, the electronic components 906 can be used to measure the pressure or flow rate of the new valve 1002 and / or measure the proximity of the electronic components 906 to determine whether the new valve has expanded properly, is functioning as intended, determine the flow rate of the valve, or determine any other parameter, characteristic, or condition related to the function of the valve and heart.

[0056]

[0072] Referring to FIG. 17, another system 1100 according to another embodiment of the present disclosure is shown. System 1100 includes electronic components 906 embedded or implanted within tumor 1102. The electronic components 906 can be implanted into the tumor in connection with another treatment or during a particular treatment. For example, the electronic components 906 can be delivered to the tumor 1102 via a needle. Although the electronic components 906 located within the mass of the tumor 1102 are shown, in some embodiments, the electronic components 906 can be implanted immediately adjacent to the tumor or strategically placed at another location in relation to the impact of the tumor on the function of an organ or anatomical structure.

[0057]

[0073] The electronic component 906 is configured as described above, powered by the ultrasonic wave 920, and has a sensor for determining parameters, characteristics, or states regarding the tumor 1102. The probe 942 includes one or more ultrasonic transducers 918 to provide power to the electronic component 906 and / or energy for communicating with the electronic component 906, as described above. In other embodiments, a patch or pad can be used as described above. In one embodiment, the electronic component 906 can include a sensor configured to detect the moisture of the tumor 1102. When the moisture of the tumor 1102 is sensed, information can be relayed back to the probe 942 (or some other device) as described herein with respect to other embodiments. The information provided by the electronic component 906 can be used to determine the density of the tumor 1102, thereby ascertaining whether the tumor 1102 has shrunk, grown, or has remained relatively unchanged from a previous determination of the tumor size. Thus, the system 1100 enables early determination of the effectiveness of treatment by frequent monitoring of the tumor being treated (e.g., by radiation, chemotherapy, or some other technique). In many cases, the prescribed treatment course shows its effectiveness at an early stage of the process. However, conventional monitoring means typically require the use of imaging modalities that are expensive and expose the patient to harmful radiation. Thus, such imaging is usually not performed until the patient has received treatment for a long period (e.g., 6 - 8 weeks). Early monitoring of the tumor's response to the treatment course using the described system (e.g., 1 or 2 weeks from the start of treatment) enables the physician to determine at an early stage whether a modification to the course is necessary, saving valuable time and resources.

[0058]

[0074] Referring now to FIG. 18, a schematic view of an exemplary patch 912 having an ultrasonic transducer 918 is shown. The patch 912 can include a flexible membrane 1200 (e.g., polyimide or other polymeric material) that can be attached to a patient's skin. Various components can be disposed on or within the membrane 1200. For example, the patch 912 can include one or more ultrasonic transducers 918 of one or more designs. In one embodiment, the ultrasonic transducer 918 can include a capacitive transducer such as a CMUT (capacitive micromachined ultrasonic transducer). In other embodiments, the transducer can include a piezoelectric transducer such as a PMUT (piezoelectric micromachined ultrasonic transducer). In some embodiments, the piezoelectric ultrasonic transducer can be formed using the techniques described above herein. The ultrasonic transducer 918 can include individual transducers or an array of ultrasonic transducers. Additionally, the transducer 918 can be configured to operate at multiple frequencies. Thus, for example, one frequency can be used to deliver power to the electronic component 906, and another frequency can be used to image a region of interest within an individual anatomical structure.

[0059]

[0075] Patch 912 can additionally include a processor 1202, such as an ASIC (application specific integrated circuit) or other suitable integrated circuit. A communication device 1204 (e.g., an integrated circuit) can be used to provide wireless communication between Patch 912 and an external device, such as a personal computer, tablet computer, smartphone, or other such device, via Bluetooth, Wi-Fi, Zigbee, or some other protocol. The external device can be used to control the patch and / or receive information from the patch, such as the time and / or duration of activation. In some embodiments, instead of or in addition to being activated or controlled by an external device, a dedicated button or switch can be provided on Patch 912 to activate Patch 912 (e.g., activate the ultrasonic transducer 918 of Patch 912). A power source 1206, such as a battery, capacitor, or connector to an external power source, can also be included to power the various components of the patch.

[0060]

[0076] The example shown in FIG. 18 shows individual components, such as one or more transducers 918 and one or more processors 1202, but such components can be integrated. For example, instead of individual transducers 918 and processors 1202, CMUT on CMOS (complementary metal oxide semiconductor) or PMUT on CMOS can be used.

[0061]

[0077] Referring further to FIG. 18, in some embodiments, a magnetic field generator 1208 (e.g., an electromagnet) can be used to assist in focusing, guiding, or otherwise manipulating ultrasonic waves (emitted waves, response waves, or both). Optionally, the magnetic field can be used to affect a disk, membrane, or other structure used to affect the backscattered response waves.

[0062]

[0078] The various embodiments of this specification are provided by way of example. However, other implementations and configurations are contemplated. For example, to assist with issues of monitoring related to AFIB such as pressure or the occurrence of potential thrombosis, electronic components (e.g., 906) can be associated with the left atrial appendage closure implant. In other embodiments, the electronic components can be implanted directly within an organ (e.g., the heart) or in combination with some other medical device to monitor desired parameters such as elasticity, density, etc. In other embodiments, the electronic components can be implanted to monitor or detect transplant rejection, regardless of whether it is cell-mediated or antibody-mediated rejection. In other embodiments, the electronic components can include electrodes for providing current or voltage at a desired location within the patient's anatomical structure when powered and directed by an external device (e.g., a patch or probe). In other embodiments, the electronic components can include a therapeutic agent that is released at a target location when powered and directed by an external device.

[0063]

[0079] The various embodiments described above can find specific applicability in applications of high-frequency ultrasonic waves (for example, frequencies of 20 MHz or higher). For example, in application examples such as intravascular ultrasound (IVUS) imaging, benefits can be obtained from such embodiments. In IVUS, in any given direction, the overall size of the transducer or transducer array may be limited to 1 mm or less. When considering a device incorporating an array of transducers operating in the range of 20 MHz to 60 MHz, the size of each array element should be from about 50 μm (micrometers) to about 10 μm. In these cases, even when microfabrication techniques are used, the area of the non-active region of the CMUT structure may substantially reduce the active area and become significantly limiting. For example, walls with a width of 8 μm to 10 μm that separate the CMT film, such as those used in conventional wafer bonding processes, may significantly reduce the active area. The walls and posts described herein help increase the transmission and reception performance of the device at the desired operating frequency, if not maximizing it. Embodiments of the present disclosure help maintain an acceptable yield and reliability of the resulting device while increasing the performance of the CMUT device.

[0064]

[0080] As used herein, the use of "adapted to" or "configured to" is open and inclusive language that does not exclude devices adapted or configured to perform additional tasks or steps. Additionally, the use of "based on" is open and inclusive in that a process, step, calculation, or other operation that is "based on" one or more recited conditions or values may actually be based on additional conditions or values other than those recited. The item names, lists, and codes included herein are for the sole purpose of facilitating explanation and are not meant to be limiting.

[0065]

[0081] The present invention may be subject to various modifications and alternative forms, but specific embodiments are shown by way of example in the drawings and are described in detail herein. However, it should be understood that the present invention is not intended to be limited to the particular forms disclosed. On the contrary, the present invention includes all modifications, equivalents, and alternative forms that fall within the spirit and scope of the present invention as defined by the following appended claims.

Claims

1. A capacitive micromachined ultrasonic transducer (CMUT) device comprising: a substrate; one or more sidewalls protruding from the substrate, the one or more sidewalls defining an outer boundary of a cavity; a membrane joined to the one or more sidewalls, the cavity being positioned between the membrane and the substrate; one or more posts protruding from the substrate, the one or more posts being sealed by the one or more sidewalls, at least a portion of the one or more posts having a width of less than 10 microns; one or more inner walls protruding from the substrate, the one or more inner walls being sealed by the one or more sidewalls. A CMUT device comprising the above components.

2. The CMUT device according to claim 1, wherein the one or more sidewalls have a width of at least 8 microns.

3. The CMUT device according to claim 1, wherein the membrane is not joined to at least a portion of the one or more posts.

4. The CMUT device according to claim 3, wherein the membrane is not joined to at least a portion of the one or more inner walls.

5. The CMUT device according to claim 4, wherein the membrane is not joined to any of the one or more posts.

6. The CMUT device according to claim 1, wherein the cavity contains a negative air pressure relative to the outside of the CMUT device.

7. The CMUT device according to claim 1, wherein the one or more posts are at least 2 microns shorter than the one or more sidewalls.

8. The CMUT device according to claim 1, wherein at least a portion of the one or more inner walls of the one or more posts has a width of less than 1 micron.

9. A method for constructing a capacitive micromachined ultrasonic transducer (CMUT) device, comprising: placing one or more sidewalls on a substrate, the one or more sidewalls defining an outer boundary of a cavity and having a width of at least 8 microns; placing one or more posts on the substrate, the one or more posts being sealed by the one or more sidewalls and at least a portion of the one or more posts having a width ranging from 1 micron to 10 microns. Placing one or more inner walls protruding from the substrate on the substrate, wherein the one or more inner walls are sealed by the one or more peripheral walls, and at least a part of the one or more inner walls includes a width of 0.5 micron to 1 micron A method comprising **Claim 10** Bonding a film to the one or more peripheral walls, wherein the cavity is positioned between the film and the substrate The method according to claim 9, further comprising **Claim 11** The method according to claim 10, wherein the step of bonding a film to the one or more peripheral walls is realized while leaving at least a part of the one or more posts unbonded to the film **Claim 12** The method according to claim 10, wherein the film is not bonded to at least a part of the one or more inner walls **Claim 13** The method according to claim 10, wherein the film is not bonded to any of the one or more posts **Claim 14** The method according to claim 9, further comprising removing air from the cavity so that a negative air pressure is generated in the cavity with respect to the outside of the CMUT device **Claim 15** The method according to claim 9, further comprising configuring the one or more posts to be at least 2 nanometers shorter than the one or more peripheral walls **Claim 16** A main body, and At least one electronic component associated with the main body Comprising, wherein the at least one electronic component At least one sensor, and At least one ultrasonic transducer configured to receive an ultrasonic signal and thereby power the at least one sensor Including A medical device, wherein the at least one electronic component is configured to provide a response ultrasonic wave in response to a determination by the at least one sensor **Claim 17** The medical device according to claim 16, wherein the at least one ultrasonic transducer includes a capacitive micromachined ultrasonic transducer (CMUT) **Claim 18** The medical device according to claim 16, wherein the at least one ultrasonic transducer includes a capacitive micromachined ultrasonic transducer (CMUT on CMOS) device on complementary metal oxide semiconductor **Claim 19** The medical device according to claim 18, wherein the at least one sensor includes at least one of a pressure sensor and a flow sensor.

20. The medical device according to claim 18, wherein the body includes a stent.

21. An external device having a first ultrasonic transducer, A medical device configured to be positioned within a patient's anatomical structure And the medical device is At least one electronic component, At least one sensor, A second ultrasonic transducer configured to receive an ultrasonic signal generated by the first ultrasonic transducer and power the at least one sensor Comprising A system, wherein the at least one electronic component is configured to provide a response ultrasonic wave to the external device in response to a determination by the at least one sensor.

22. The system according to claim 21, wherein at least one of the first ultrasonic transducer and the second ultrasonic transducer includes a capacitive micromachined ultrasonic transducer (CMUT).

23. The system according to claim 22, wherein the at least one of the first ultrasonic transducer and the second ultrasonic transducer includes a capacitive micromachined ultrasonic transducer on complementary metal oxide semiconductor (CMUT on CMOS) device.

24. The system according to claim 21, wherein the at least one sensor includes at least one of a pressure sensor and a flow sensor.

25. The system according to claim 21, wherein the at least one sensor is configured to detect at least one of a blood glucose level, a pH level, a CO2 concentration, an oxygen concentration, a pressure, and a temperature.

26. The system according to claim 21, wherein the at least one sensor is configured to detect the moisture of a tumor.

27. The system according to claim 21, wherein the at least one electronic component is coupled to a stent.

28. The system according to claim 21, wherein the at least one electronic component is coupled to an aortic valve.

29. The system according to claim 21, wherein the external device includes a patch configured to adhere to a patient's skin.

30. The system according to claim 21, wherein the external device includes a handheld probe.

31. The system according to claim 21, wherein the external device includes a magnetic field generator.

32. The system according to claim 21, wherein the external device includes a power source, a processor, and a wireless communication device.

33. Transplanting electronic components adjacent to or within a tumor within a patient; Powering the electronic components using ultrasonic energy; Detecting the moisture of the tumor using a sensor of the electronic components; Providing a response signal from the electronic components to an external device based on the detected moisture; Determining the density of the tumor or a change in the density of the tumor based on the response signal and including a method.

34. A flexible elongate member having a distal portion configured to be inserted into a blood vessel of a patient; An imaging device disposed within the distal portion of the flexible elongate member and comprising the imaging device A flexible substrate; A plurality of ultrasonic transducers disposed on the flexible substrate, each of the plurality of ultrasonic transducers comprising a capacitive micromachined ultrasonic transducer (CMUT on CMOS) device on a complementary metal oxide semiconductor; a plurality of ultrasonic transducers; A tail extending from the flexible substrate and having a plurality of connection pads and including a medical device.

35. The medical device according to claim 34, wherein the plurality of ultrasonic transducers are circumferentially arranged around the longitudinal axis of the flexible elongate member.

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