Patent Application
20210298617
The present disclosure relates to capacitive pressure sensors for intraluminal pressure-sensing guidewires and/or catheters. In some embodiments, a capacitive pressure sensor with three capacitive cells is provided.
Heart disease is very serious and often requires emergency operations to save lives. A main cause of heart disease is the accumulation of plaque inside the blood vessels, which eventually occludes the blood vessels. Common treatment options available to open up the occluded vessel include balloon angioplasty, rotational atherectomy, and intravascular stents. Traditionally, surgeons have relied on X-ray fluoroscopic images that are planar images showing the external shape of the silhouette of the lumen of blood vessels to guide treatment. Unfortunately, with X-ray fluoroscopic images, there is a great deal of uncertainty about the exact extent and orientation of the stenosis responsible for the occlusion, making it difficult to find the exact location of the stenosis. In addition, though it is known that restenosis can occur at the same place, it is difficult to check the condition inside the vessels after surgery with X-ray.
A currently accepted technique for assessing the severity of a stenosis in a blood vessel, including ischemia causing lesions, is fractional flow reserve (FFR). FFR is a calculation of the ratio of a distal pressure measurement (taken on the distal side of the stenosis) relative to a proximal pressure measurement (taken on the proximal side of the stenosis). FFR provides an index of stenosis severity that allows determination as to whether the blockage limits blood flow within the vessel to an extent that treatment is required. The normal value of FFR in a healthy vessel is 1.00, while values less than about 0.80 are generally deemed significant and require treatment.
Another way of assessing blood vessels is to use ultrasound imaging. For example, ultrasound imaging arrays formed of capacitive micromachined ultrasound transducers (CMUTs) have been investigated. Manufacturing CMUT arrays, however, is difficult because of non-uniformities that arise. For example, membranes behave differently based on whether they are located in the middle of the array or whether they are at the edge or corner of the array. Such non-uniformity is untenable because medical sensors need to behave in the same, predictable manner. These challenges prevent the full range of capacitive sensors for assessing blood vessels from being realized.
Embodiments of the present disclosure are directed to capacitive pressure sensors for intraluminal guidewires and/or catheters. For example, the capacitive pressure sensor can be implemented in an intravascular guidewire and used to measure the pressure of blood flow within the blood vessel of a patient. The capacitive pressure sensor includes two active cells and one dummy cell. The two active cells electrically communicate with other components of the capacitive pressure sensor and are used to measure pressure.
In an exemplary aspect, an intraluminal pressure-sensing device is provided, comprising:
a flexible elongate member configured to be positioned within a body lumen of a patient;
a housing coupled to the flexible elongate member, a capacitive pressure sensor disposed within the housing;
In an embodiment, the intraluminal device further comprises a dummy cell formed on the proximal portion of the substrate, wherein the dummy cell does not provide electrical signal representative of the external pressure. In one aspect, the first active cell and the second active cell are spaced from one another by a first pitch. In one aspect, the dummy cell is spaced from at least one of the first active cell or the second active cell by a different, second pitch. In one aspect, the first active cell, the second active cell, and the dummy cell are arranged longitudinally along the substrate. The benefit of this aspect is that pulse wave velocity of the blood vessel can be measured by the timelag between the measured pressure pulses, the measurement not being affected by the forces that act on the device due to bending of the vessel. In one aspect, the first active cell and the second active cell comprise a first diameter, and the dummy cell comprises a different, second diameter.
In one aspect, the capacitive pressure sensor further includes an integrated circuit disposed in the substrate, wherein the integrated circuit is in communication with the first active cell and the second active cell. Accordingly, the integrated circuit is advantageously free from the influence of any forces that may adversely impact operation of the integrated circuit and the active cells to measure the pressure of the fluid within the lumen. Instead, the active cells and the integrated circuit experience only the external pressure of the fluid within the lumen. In one aspect, the capacitive pressure sensor further includes a first bond pad formed in the substrate; and a second bond pad formed in the substrate, wherein the first bond pad and the second bond pad are in communication with the integrated circuit. In one aspect, the first active cell and the second active cell are symmetrical about an axis of the substrate. In one aspect, the substrate comprises a proximal portion comprising a first dimension and a distal portion comprising a smaller, second dimension, and the first active cell and second active cell are formed in the distal portion. In one aspect, the capacitive pressure sensor further includes an integrated circuit disposed in the distal portion of the substrate, wherein the integrated circuit is in communication with the first active cell and the second active cell.
In one aspect, the intraluminal pressure-sensing device further includes a first electrical conductor and a second electrical conductor only, wherein the first electrical conductor and the second electrical conductor are in communication with the integrated circuit, wherein the capacitive pressure sensor is coupled to a distal portion of the flexible elongate member, wherein the first electrical conductor and the second electrical conductor extend from the distal portion of the flexible elongate member to a proximal portion of the flexible elongate member, and wherein at least one of the first electrical conductor or the second electrical conductor are configured to transmit the electrical signal representative of the sensed pressure from the capacitive pressure sensor at the distal portion of the flexible elongate member to a connector at the proximal portion of the flexible elongate member. In one aspect, the intraluminal pressure-sensing device further includes a first bond pad formed in the substrate; and a second bond pad formed in the substrate, wherein the first bond pad and the second bond pad are in communication with the integrated circuit, and wherein the first electrical conductor and the second electrical conductor are respectively in communication with the first bond pad and the second bond pad. In one aspect, the intraluminal pressure-sensing device further includes a housing coupled to the flexible elongate member, wherein the capacitive pressure sensor is disposed within the housing. In one aspect, the substrate of the capacitive pressure sensor comprises a proximal portion coupled to the housing and a cantilevered distal portion, wherein the first active cell and the second active cell are formed in the cantilevered distal portion. In one aspect, the intraluminal pressure-sensing device further includes an integrated circuit disposed in the cantilevered distal portion of the substrate, wherein the integrated circuit is in communication with the first active cell and the second active cell. In one aspect, the flexible elongate member comprises a guidewire. In one aspect, the flexible elongate member comprises a catheter.
In an exemplary embodiment of the intravascular device the dummy cell is configured to provide ultrasound based flow velocity measurement and/or ultrasound imaging signals the benefit is that additional information on the pressure measurement conditions is provided, for example on how far the vessel wall is located with respect to the pressure sensor, or weather there is a difference in the pulsating flow velocity in the blood vessel with respect to the pulsating blood pressure, which is a measure of health condition of the vessel.
In a further exemplary embodiment of the intravascular device the extent of overlap of the integrated circuit with the first and second active cell is substantially equal.
In yet another exemplary embodiment of the device the first and second active cells comprise a central pillar extending vertically from the substrate to a membrane, and wherein the first and second active cells are of an annular form around the central pillar. The benefit is the stability of the active cells.
In a further embodiment of the device the integrated circuit is configured to output an electrical signal representative of a ratio of the sensed pressures at the first active cell and the second active cell.
In an exemplary aspect, a system is provided. The system includes an intrvascular pressure-sensing device according to any of the previously disclosed embodiment; and a computer in communication with the capacitive pressure sensor, wherein the computer is configured to generate a pressure value based on the electrical signals representative of the external pressure and to output, to a display, a visual representation of the pressure value.
Additional aspects, features, and advantages of the present disclosure will become apparent from the following detailed description.
Illustrative embodiments of the present disclosure will be described with reference to the accompanying drawings, of which:
For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It is nevertheless understood that no limitation to the scope of the disclosure is intended. Any alterations and further modifications to the described devices, systems, and methods, and any further application of the principles of the present disclosure are fully contemplated and included within the present disclosure as would normally occur to one skilled in the art to which the disclosure relates. In particular, it is fully contemplated that the features, components, and/or steps described with respect to one embodiment may be combined with the features, components, and/or steps described with respect to other embodiments of the present disclosure. For the sake of brevity, however, the numerous iterations of these combinations will not be described separately.
Referring now to
The intraluminal device 110 can be a guidewire, catheter, and/or guide catheter. The intraluminal device 110 can be referenced as a pressure-sensing device, a pressure-sensing guidewire, a pressure-sensing catheter, a diagnostic device, and/or combinations thereof in some instances. In the illustrated embodiment of
The flexible elongate member 116 can be tubular in shape in some instances. The intraluminal device 110 may or may not include one or more lumens extending along all or a portion of the length of the flexible elongate member 116. One or more components forming the intraluminal device 110 can be positioned within the one or more lumens of the flexible elongate member 116. The lumen of the flexible elongate member 116 can be sized and shaped, structurally arranged, and/or otherwise configured to receive and/or guide one or more other diagnostic and/or therapeutic instruments. If the flexible elongate member 116 includes lumen(s), the lumen(s) may be centered or offset with respect to the cross-sectional profile of the intraluminal device 110. The intraluminal device 110 can be a catheter including a lumen configured to receive a guidewire. During a diagnostic and/or therapeutic procedure, a medical professional typically first inserts the guidewire into the body lumen and moves the guidewire to a desired location within the anatomy. The guidewire facilitates introduction and positioning of one or more other diagnostic and/or therapeutic instruments, such as a catheter, at the desired location within the anatomy. In some embodiments, the lumen of the intraluminal device 110 can extend along the entire length or a portion of the length of the flexible elongate member 116.
The flexible elongate member 116 can include any suitable components formed of different materials. As shown
The anatomy 102 may represent any fluid-filled or surrounded structures, both natural and man-made. For example, the anatomy 102 can be within the body of a patient. Fluid can flow through the lumen 104 of the anatomy 102. The lumen 104 can be referenced as a body lumen in some instances. The anatomy 102 can be a vessel, such as a blood vessel, in which blood flows through the lumen 104. In such instances, the intraluminal device 110 can be referenced as an intravascular device. In various embodiments, the blood vessel is an artery or a vein of a patient's vascular system, including cardiac vasculature, peripheral vasculature, neural vasculature, renal vasculature, and/or any other suitable anatomy/lumen inside the body. The anatomy 102 can be tortuous in some instances. For example, the intraluminal device 110 may be used to examine any number of anatomical locations and tissue types, including without limitation, organs including the liver, heart, kidneys, gall bladder, pancreas, lungs, esophagus; ducts; intestines; nervous system structures including the brain, dural sac, spinal cord and peripheral nerves; the urinary tract; as well as valves within the blood, chambers or other parts of the heart, and/or other systems of the body. In addition to natural structures, the intraluminal device 110 may be used to examine man-made structures such as, but without limitation, heart valves, stents, shunts, filters and other devices. Embodiments of the present disclosure are particularly suited for use in the context of human anatomy. In some aspects, the present disclosure can be generally used in a lumen of an anatomical or non-anatomical structure, including both medical and non-medical applications.
The occlusion 106 of the anatomy 102 is generally representative of any blockage or other structural arrangement that results in a restriction to the flow of fluid through the lumen 104, for example, in a manner that is deleterious to the health of the patient. For example, the occlusion 106 narrows the lumen 104 such that the cross-sectional area of the lumen 104 and/or the available space for fluid to flow through the lumen 104 is decreased. Where the anatomy 102 is a blood vessel, the occlusion 106 may be a result of plaque buildup, including without limitation plaque components such as fibrous, fibro-lipidic (fibro fatty), necrotic core, calcified (dense calcium), blood, fresh thrombus, and/or mature thrombus. In some instances, the occlusion 106 can be referenced as thrombus, a stenosis, and/or a lesion. Generally, the composition of the occlusion 106 will depend on the type of anatomy being evaluated. Healthier portions of the anatomy 102 may have a uniform or symmetrical profile (e.g., a cylindrical profile with a circular cross-sectional profile). The occlusion 106 may not have a uniform or symmetrical profile. Accordingly, diseased portions of the anatomy 102, with the occlusion 106, will have a non-symmetric and/or otherwise irregular profile. While the anatomy 102 is illustrated in
The intraluminal device 110 includes a pressure sensor 150 coupled to the flexible elongate member 116. As described herein, the pressure sensor 150 can be a capacitive pressure sensor. The pressure sensor 150 can be directly or indirectly coupled to the distal portion 112 of the flexible elongate member 116, proximal of the distal end 113. In some instances, the pressure sensor 150 is positioned less than 10 cm, less than 5, or less than 3 cm from the distal end 113. The pressure sensor 150 is configured to sense external pressure within the lumen 104, such as external pressure associated with the fluid flow within the lumen 104. The pressure sensor 150 generates electrical signals representative of the external pressure and transmits the electrical signals via conductors 140, 142. The conductors 140, 142 individual or collectively can be referenced as electrical conductors, wires, cables, etc. A distal portion of the conductors 140, 142 is mechanically and/or electrically coupled to the pressure sensor 150. As described herein, in some instances, electronic circuitry can be coupled to and/or integrated in the distal portion 112 of the flexible elongate member 116, such as adjacent to, proximal to, and/or integrated in the pressure sensor 150. The electronic circuitry can process electrical signals generated by the sensor and output an electrical signal representative of a sensed pressure. The electrical signals are transmitted from the pressure sensor 150 at the distal portion 112 to the proximal portion 114 of the flexible elongate member 116. The conductors 140, 142 extend along the length of the flexible elongate member 116, from the distal portion 112 to the proximal portion 114. The conductors 140, 142 can carry electrical signals from the PIM 119 and/or the computer 120 to the pressures sensor 150. The electrical signals transmitted to the pressure sensor 150 can be power to activate and operate the pressure sensor 150 and/or control signals to control operation of the pressure sensor 150.
In some embodiments, the intraluminal device 110 includes only two conductors 140, 142. Two conductors 140, 142 can be referred to as a bifilar cable in some instances. Use of only two conductors 140, 142 advantageously minimizes the amount of space taken up by conductors within the intraluminal device 110, compared to larger numbers of conductors. The space within the intraluminal device 110 that is made available by using only two conductors 140, 142 can be advantageously utilized for other components of the intraluminal device 110, such as by making some components larger or adding additional components that provide different functionality while maintaining the same outer diameter of intraluminal device 110. In other instances, the outer diameter of the intraluminal device 110 can be made smaller. In other embodiments, any number of conductors can extend along the length of the flexible elongate member 116 between the connector 117 and the pressure sensor 150, including between one and ten conductors. It is understood that some portion or length of the conductors 140, 142 may be bare while other portions of the conductors 140, 142 may be insulated and/or shielded. For example, a distal end and a proximal end of the conductors 140, 142 can be bare to allow for mechanical and/or electrical interconnection with other components (e.g., by soldering). As shown in the illustrated embodiment of
While electrical signals are mentioned, it is understood that the signals representative of the external pressure applied on the pressure sensor 150 can be any suitable signal type, such as optical signals, radio frequency signals, etc. In lieu of or in addition to conductors 140, 142, any suitable communication pathway(s) or communication line(s), wired or wireless, can be implemented in the intraluminal device 110, including an optical fiber, a fiber optical cable, wireless transmission via an antenna integrated in and/or coupled to the distal portion 112 or the proximal portion 114 of the flexible elongate member 116, etc. Generally, the pressure sensor 150 can be any suitable functional device, such as one or more electronic, optical, or electro-optical components. For example, the functional device can be a pressure sensor, a flow sensor (velocity and/or volume), a temperature sensor, an imaging element, an optical fiber, an ultrasound transducer, a reflector, a mirror, a prism, an optical coherence tomography (OCT) element, an ablation element, an RF electrode, a conductor, and/or combinations thereof.
The intraluminal device 110 includes a connector 117 at or adjacent to the proximal portion 114 of the flexible elongate member 116. In some instances, the connector 117 forms part of the proximal end 115 of the flexible elongate member 116. For example, as shown in
The intraluminal device 110 can include a housing 130 in which the pressure sensor 150 is disposed. The housing 130 can be referenced as a sensor housing in some embodiments. The housing 130 includes an opening 132 that exposes the pressure sensor 150 to the fluid within the lumen 104 of the anatomy 102. The housing 130 is coupled to the flexible elongate member 116. For example, the housing 130 can be directly or indirectly coupled to the distal portion 112 of the flexible elongate member 116, proximal of the distal end 113. In some instances, the housing is positioned less than 10 cm, less than 5, or less than 3 cm from the distal tip 105. The housing 130 can be a structure formed of any suitable material, such as a metal, metal alloy, plastic, and/or polymer. In some instances, the housing is a separate component secured to the flexible elongate member 116 in some instances. In other instances, the housing is integrally formed as a part of the flexible elongate member 116. The housing 130 can be tubular structure including a lumen in which one or more components, including the pressure sensor 150 are positioned.
The system 100 can include a connector 118 that is removably coupled to intraluminal device 110. For example, the connector 118 can be mechanically and/or electrically connected to the connector 117 at the proximal portion 114 of the flexible elongate member 116 at the start of a pressure-sensing procedure and disconnected at the end of the procedure. The connector 118 can facilitate communication of data between intraluminal device 110 (e.g., the pressure sensor 150 via the conductors 140, 142 and the connector 117) and another device, such as the PIM 119 and computer 120. For example, the connector 118 can be in direct communication with the PIM 119. Accordingly, in some embodiments, the connector 117 is an electrical connector that provides an electrical connection to the connector 117 of the intraluminal device 110. In other embodiments, the connector 118 is an optical connector and/or other suitable wired or wireless communication pathway. In some instances, the connector 118 is configured to provide a physical connection to another device, either directly or indirectly.
The PIM 119 of the system 100 includes electronic circuitry associated with signals to and from the pressure sensor 150 and the computer 120. In that regard, the PIM 119 is communicatively coupled to the intraluminal device 110 and the computer 120. For example, the PIM 119 can perform processing of the electrical signals received from the pressure sensor 150. The PIM 119 can transmit power and/or control signals to the pressure sensor 150 from the PIM itself and/or the computer 120. The PIM 119 can include one or more processor and memory in some instances to implement hardware and/or software associated with signals to and from the pressure sensor 150 and the computer 120. In some instances, the system 100 does not include the PIM 119, and the intraluminal device 110 communicates with the computer 120 without the PIM 119.
The computer 120 is communicatively coupled to the PIM 119 and/or the intraluminal device 110 (e.g., the pressure sensor 150 and/or electronic circuitry integrated in the pressure sensor 150 and/or the flexible elongate member 116). The computer 120 is generally representative of any one or multiple computing devices suitable for processing and analyzing the data obtained the pressure sensor 150 and/or controlling the operation of the pressure sensor 150. The computer 120 includes one or more processors 122 in communication with any suitable memory 124. The memory 124 can be referenced as a non-transitory computer readable storage medium in some instances. It is understood that any steps related to data acquisition, data processing, instrument control, and/or other processing or control aspects of the present disclosure may be implemented by the computer 120 using corresponding instructions stored on or in the memory 124 and executed by the processor 122. In some instances, the computer 120 is a console device. In some instances, the computer 120 is portable (e.g., handheld, on a rolling cart, etc.).
Generally, the computer 120 is configured to receive the electrical signals from the pressure sensor 150 representative of the sensed pressure within the lumen 104 of the anatomy 102. The computer 120 processes the electrical signals to generate a pressure value. The pressure value can be the sensed pressure within the lumen 104. In some instances, the pressure value can be a pressure ratio calculated by computer 120 based on the sensed pressure, such as a fractional flow reserve (FFR) value, an instantaneous wave-free ratio (iFR) value, a Pd/Pa (distal pressure/aortic pressure) value, and/or other pressure ratio value. The computer 120 can be in communication with another pressure sensor, such as an aortic pressure sensor, a pressure-sensing guidewire, or a pressure-sensing catheter. The computer 120 can calculate the pressure ratio based on the sensed pressure from the pressure sensor 150 and the sensed pressure from the other pressure sensor. The computer 120 generates a visual representation based on the pressure value and outputs the visual representation to the display 125. The visual representation can include a numerical value, symbol, plot, graph, chart, image, and/or other suitable graphical representations of the sensed pressure and/or the calculated pressure ratio. The display 125 can be any suitable monitor, such as a standalone device or can be integrated in a housing of the computer 120.
Referring now to
The active cells 160a, 160b include a dimension 196, which may be diameter. In some embodiments, the dimension 196 can be between approximately 100 μm and approximately 170 μm, between approximately 120 μm and approximately 150 μm, and/or between approximately 130 μm and 140 μm, including values such as 130 μm, 133 μm, 135 μm, 137 μm, 140 μm, and/or other suitable values both larger and smaller. The dimension 196 of the active cells 160a, 160b can be equal to one another. Generally, the structure of the active cells 160a, 160b is the identical such that the behavior of the active cells 160a, 160b under the influence of external pressure is identical. In other embodiments, the size, shape, and/or other structural aspects of the active cells 160a, 160b are different from one another.
The dimension 196 of the active cells 160a, 160b may be different than a corresponding dimension 197, such as a diameter, of the dummy cell 164. For example, the dimension 197 of the dummy cell 164 may be less than then dimension 196 of the active cells 160a, 160b. In some embodiments, the dimension 197 can be between approximately 100 μm and approximately 170 μm, between approximately 120 μm and approximately 150 μm, and/or between approximately 130 μm and 140 μm, including values such as 127 μm, 130 μm, 133 μm, 135 μm, 137 μm, and/or other suitable values both larger and smaller. In other embodiments, the dimension 196 of the active cells 160a, 160b is equal to the dimension 197 of the dummy cell 164.
The substrate 151 includes a surface 153 on which the active cells 160a, 160b, the dummy cell 164, and the bonds pads 170, 172 are formed, and an opposite surface 155. As shown in
In the illustrated embodiment, the active cells 160a, 160b and the dummy cell 164 are arranged longitudinally along the pressure sensor 150 and/or the substrate 151. For example, the active cells 160a, 160b and the dummy cell 164 are disposed in the substrate 151 adjacent to or proximate to one another along a dimension 180, such as a length, of the pressure sensor 150 and/or along the longitudinal axis LA. The active cells 160a, 160b and the dummy cell 164 can be arranged in a line. For example, when the longitudinal axis LA is a central longitudinal axis of the pressures sensor 150, the mid-points of the active cells 160a, 160b and the dummy cell 164 are disposed along the central longitudinal axis. In other embodiments, the active cells 160a, 160b and the dummy cell 164 are arranged in different configurations. For example, one or more of the active cells 160a, 160b and the dummy cell 164 are positioned side-by-side laterally and/or laterally offset from one another or from the central longitudinal axis.
The pressure sensor 150 and/or the substrate 151 includes a distal portion 152 and a proximal portion 154. The active cells 160a, 160b can be formed at the distal portion 152. Bond pads 170, 172 can be formed in the substrate 151 at the proximal portion 154. The bond pads 170, 172 extend longitudinally along the along the pressure sensor 150 and/or the substrate 151. The bond pads 170, 172 are arranged side-by-side laterally in the illustrated embodiment, in a direction perpendicular to the longitudinal axis LA (e.g., a transverse dimension of the pressure sensor 150 and/or the substrate 151). Different configurations for the bond pads 170, 172 in different embodiments are contemplated. The bond pads 170, 172 includes a conductive material that is directly or indirectly in communication with the active cells 160a, 160b as a result of conductive traces or other conductive signal pathways formed in the substrate 151. For example, the bond pads 170, 172 can be in communication with the integrated circuit 200. The distal end of the conductors 140, 142 are mechanically and/or electrically coupled to the bond pads 170, 172, respectively, thereby establishing electrical communication between the conductors 140, 142 and the active cells 160a, 160b. For example, the distal end of the conductors 140, 142 are soldered to the bond pads 170, 172, respectively, thereby mechanically coupling and establishing communication between the conductors 140, 142 and the bond pads 172. The dimensions of the bond pads 170, 172 (e.g., a length and a width) provide space for the conductors 140, 142, and the solder. The dummy cell 164 can be located at least partially in the proximal portion 154 and/or in a middle portion between the distal portion 152 and the proximal portion 154.
The substrate 151 is formed into any suitable size and shape such that the pressure sensor 150 can be implemented in the intraluminal device 110. In that regard, the substrate 151 is sized and shaped, structurally arranged, and/or otherwise configured to be disposed within the housing 130, coupled to the intraluminal device 110 and/or positioned within the lumen 104 of the anatomy 102. In the illustrate embodiment, the pressure sensor 150 and/or the substrate 151 is formed into a bottle shape, with the distal portion 152 being the neck of the bottle, the proximal portion 154 being the body of the bottle, and a transition 194 between the distal portion 152 and the proximal portion 154 being the shoulder of the bottle. In other embodiments, the pressure sensor 150 is formed in any suitable geometric or non-geometric shape. The substrate 151 can be any suitable semiconductor material, such as a silicon (Si) substrate or a germanium (Ge) substrate. In some embodiments, the substrate 151 may include a compound semiconductor such as silicon carbide (SiC), silicon germanium (SiGe), silicon germanium carbide (SiGeC). In some implementations, the substrate 151 may be a silicon on insulator (SOI) substrate.
As shown in
The distal portion 152 of the substrate 151 includes a dimension 190, which may be width of the distal portion 152. In some embodiments, the dimension 190 can be between approximately 120 μm and approximately 200 μm, between approximately 140 μm and approximately 180 μm, and/or between approximately 155 μm and 165 μm, including values such as 150 μm, 155 μm, 158 μm, 160 μm, 162 μm, 165 μm, 170 μm, and/or other suitable values both larger and smaller. The proximal portion 154 of the substrate 151 includes a dimension 192, which may be width of the proximal portion 154. In some embodiments, the dimension 192 can be between approximately 150 μm and approximately 250 μm, between approximately 175 μm and approximately 225 μm, and/or between approximately 190 μm and 210 μm, including values such as 190 μm, 195 μm, 198 μm, 200 μm, 202 μm, 205 μm, 210 μm, and/or other suitable values both larger and smaller. In some embodiments, the dimension 190 of the distal portion 152 is smaller than the corresponding dimension 192 of the proximal portion 154. For example, the proximal portion 154 is wider than the distal portion 152. The transition 194 transitions from the larger dimension 192 of the proximal portion 154 to the smaller dimension 190 of the distal portion 152. In the illustrate embodiment, the transition 194 is linear. In other embodiments, the transition 194 may be curved.
The distal portion 152 of the substrate 151 includes a dimension 182, which may be length of the distal portion 152. In some embodiments, the dimension 182 can be between approximately 250 μm and approximately 350 μm and/or between approximately 375 μm and approximately 425 μm, including values such as 290 μm, 300 μm, 302 μm, 310 μm, and/or other suitable values both larger and smaller. The proximal portion 154 of the substrate 151 includes a dimension 184, which may be length of the proximal portion 154. In some embodiments, the dimension 184 can be between approximately 340 μm and approximately 400 μm and/or between approximately 350 μm and approximately 390 μm, including values such as 360 μm, 370 μm, 373 μm, 380 μm, and/or other suitable values both larger and smaller. The transition 194 of the substrate 151 includes a dimension 186, which may be length of the transition 194. In some embodiments, the dimension 186 can be between approximately 25 μm and approximately 100 μm and/or between approximately 60 μm and approximately 90 μm, including values such as 70 μm, 80 μm, 90 μm, and/or other suitable values both larger and smaller.
Referring now to
The basic principal of the active cells 160a, 160b is a parallel-plate capacitor between electrodes provided in the membrane 168 and the substrate 151, at a base 165 of the cavity 161. The electrode at the base 165 is fixed, while membrane 168 and/or the electrode in the membrane 168 moves in response to the external pressure applied to the pressure sensor 150. The active cells 160a, 160b transmit electrical signals representative of the change in capacitance resulting from movement of the membrane 168. The integrated circuit 200 receives the electrical signals output by the active cells 160a, 160b. The integrated circuit 200, the PIM 119, and/or the computer 120 use the electrical signals to measure the pressure of the fluid flow within the lumen 104 of the anatomy 102. In an exemplary embodiment, the active cells 160a, 160b are electrically connected to one another in parallel such that the respective capacitances measured by the active cells 160a, 160b is added (e.g. C1+C2). In other embodiments, the active cells 160a, 160b can be connected in series or not connected to one another. The dummy cell 164 is not electrically coupled to the integrated circuit 200 and does not transmit the electrical signals representative of the sensed pressure. The dimension 196 of the active cells 160a, 160b can be a dimension (e.g., diameter) of the membrane 168 in some embodiments. n some embodiments, the active cells 160a, 160b and the dummy cell 164 are annular capacitive cells. For example, as shown in
As shown in
The integrated circuit 200 is directly or indirectly in communication with the conductors 140, 142. For example, the integrated circuit 200 is electrically coupled to the conductors 140, 142 via the bonds pads 170, 172, conductive traces, and/or other conductive signal pathways formed in the substrate 151. In that regard, the bond pads 170, 172 are electrically coupled to the integrated circuit 200. The integrated circuit 200 transmits an electrical signal via at least one of the conductors 140, 142. The integrated circuit 200 is configured to output an electrical signal representative of a sensed pressure at the active cells 160, 160b. In an exemplary embodiment, the integrated circuit 200 outputs an alternating current (AC) signal. In that regard, one of the conductors 140, 142 can be at electrical ground (e.g., 0 V) and the other conductor can carry an electrical signal providing power to the active cells 160a, 160b and/or the integrated circuit 200 (any suitable voltage, such as a 2.5 V, 3.0 V, and/or other values both larger and smaller). The power supply voltage can be transmitted to the pressure sensor 150 by the PIM 119 and/or the computer 120. In an exemplary embodiment, the integrated circuit 200 can generally behave as an RC oscillator with an oscillation frequency f proportional to
The oscillation frequency can also be referenced as an output frequency in some instances. The oscillation frequency is based on the capacitances of the two of the active cells 160a, 160b. When the active cells 160a, 160b are electrically connected in parallel, the electrical signal output by the integrated circuit 200 has an oscillation frequency
When the external pressure is exerted on the active cells 160a, 160b, causing the membrane 161 to deflect towards the base 165 of the cavity 161, the capacitances increase and the oscillation frequency decreases. With less pressure or no pressure is exerted on the active cells 160a, 160b, the membrane 161 deflects away from the base 165, causing the capacitances to decrease and the oscillation frequency to increase. The oscillations in the electrical signal output by the integrated circuit 200 are provided on top of the power supply voltage (e.g., 2.5 V, 3 V) carried by one of the conductors 140, 142. The conductor 140 and/or 142 can transmit the electrical signal representative of the sensed pressure from the capacitive pressure sensor 150 at the distal portion 112 of the flexible elongate member 116 to the connector 117 at the proximal portion 114 of the flexible elongate member 116. The PIM 119 and/or the computer 120, which are in communication with the connector 117, detect the frequency in the electrical signal carried by one of the conductors 140, 142, resulting from the output of the integrated circuit 200. For example, the oscillation frequency at the bond pads 170, 172 is representative of the sensed pressure at the active cells 160a, 160b. The PIM 119 and/or computer 120 determines the sensed pressure at the active cells 160a, 160b based on the electrical signal carried by the conductors 140, 142. For example, the computer 120 utilizes a calibration curve describing the relationship between oscillation frequency and the sensed pressure. In some instances, the calibration curve is a generally smooth curve with a negative slope. That is, the lower the oscillation frequency, the higher the sensed pressure. Likewise, the higher the oscillation frequency, the lower the sensed pressure. The computer 120 can utilize any suitable mathematical relationship and/or function between oscillation frequency and the sensed pressure to determine the sensed pressure based on the electrical signal output by the integrated circuit 200.
The integrated circuit 200 is disposed in the substrate 151. For example, the integrated circuit 200 can be disposed in the distal portion 152 of the substrate 151. In the illustrated embodiment, the integrated circuit 200 is completely surrounded by the substrate 151. In other embodiments, the integrated circuit 200 can be disposed in the substrate 151 at the surface 153 or the surface 155. For example, a surface of the integrated circuit 200 can extend continuously with the surface 153 or the surface 155. The pressure sensor 150 may only include one integrated circuit 200, which may be disposed in the substrate 151 below the active cell 160a and/or the active cell 160b. In an exemplary embodiment, the integrated circuit 200 is sized and shaped such that it is partially positioned under each of the active cells 160a, 160b and a region between active cells 160a, 160b. The integrated circuit 200 can be symmetrically disposed below the active cells 160a, 160b. In that regard, the integrated circuit 200 has a midpoint that is co-located with a midpoint between the active cells 160a, 160b. For example, as shown in
The integrated circuit 200 includes a dimension 203, such as a width of the integrated circuit 200. In some embodiments, the dimension 203 can be between approximately 50 μm and approximately 60 μm, including values such as 53 μm, 55 μm, 57 μm, and/or other suitable values both larger and smaller. In such embodiments, the dimension 203 of the integrated circuit 203 can be smaller than the dimension 196 of the active cell 160a. In that regard, the dimension 196 of the active cell 160 can be a width or a diameter of the cavity 161. The integrated circuit 200 includes a dimension 205, such as a height of the integrated circuit 200. In some embodiments, the dimension 205 can be between approximately 5 μm and approximately 25 μm and/or between approximately 10 μm and approximately 20 μm, including values such as 10 μm, 15 μm, 20 μm, and/or other suitable values both larger and smaller. In an exemplary embodiment, the dimension 205 of the integrated circuit 203 is larger than the dimension 163 of the cavity 161. A dimension 207 (
Referring again to
Referring now to
The proximal portion 154 of the pressure sensor 150 can be coupled to the mount 134. Generally, the proximal portion 154 can be directly or indirectly coupled to the mount 134 and/or the housing 130 in which the mount 134 is positioned. In general, mechanical coupling, attachment, connection, and/or securing between components can include direct or indirect fastening where one or more other components are disposed between coupled components. For example, components can be mechanically coupled using an adhesive, mechanical fasteners, welding, and/or other suitable attachment. The dummy cell 164 can be disposed mostly in the proximal portion 154.
The distal portion 152 of the pressure sensor 150 is cantilevered, with a gap 138 between the pressure sensor 150 and the mount 134. Because it is cantilevered, the distal portion 152 is advantageously isolated from any forces experienced by the intraluminal device 110, the housing 130, and/or the mount 134 resulting from the intraluminal device 110 navigating the anatomy 102 (e.g., deformation of the intraluminal device 110, the housing 130, and/or the mount 134 caused by bending in tortuous vasculature or contacting tissue while crossing the occlusion 106). The distal portion 152 is also advantageously isolated from any forces experienced by the pressure sensor 150 during assembly of the intraluminal device 110, such as when the proximal portion 154 is coupled to the mount 134. In the illustrated embodiment, the active cells 160a, 160b and the integrated circuit 200, are disposed within the cantilevered distal portion 152. Accordingly, the active cells 160a, 160b and the integrated circuit 200 are advantageously free from the influence of any forces that may adversely impact operation (e.g., the output signals) of the active cells 160a, 160b and the integrated circuit 200 to measure the pressure of the fluid within the lumen 104. Instead, the active cells 160a, 160b experience only the external pressure of the fluid within the lumen 104. In that regard, the active cells 160a, 160b are exposed to the fluid within the lumen 104 through the opening 132 in the housing 130. Any forces associated with deformation of the intraluminal device 110, the housing 130, and/or the mount 134 are experienced by the dummy cell 164, which is not electrically active and is not involved in measuring pressure.
Referring now to
Referring now to
As shown in
In that regard, the dummy cells 164a, 164b, 164c, 164d surround the active cells 160a, 160b. The dummy cells 164c are positioned above and below every pair of active cells 160a, 160b in the die 310. The dummy cells 164a are positioned to the left of the active cells 160a, 160b. The dummy cells 164b are positioned to the right of the active cells 160a, 160b. The dummy cells 164d are positioned diagonally of the active cells 160a, 160b. The directional descriptions such as above, below, left, right, and diagonal are used with reference to the orientation and arrangement of components in
The dense arrangement of capacitive cells in the die 310 advantageously ensures uniformity in the active cells 160a, 160b. For example, compared to one another, the active cell 160a and the active cell 160b of the pressure sensor 150a respond similarly or identically to the external pressure of the fluid within the lumen 104 of the anatomy 102. Likewise, the active cells 160a, 160b of the pressure sensor 150a and those of the pressure sensors 150b, 150c, respond similarly or identically to the external pressure of the fluid within the lumen 104. Additionally, the active cells 160a, 160b of the pressure sensor 150 and those of a pressure sensor fabricated on a different die 310 and/or a different wafer 300 respond similarly or identically to the external pressure of the fluid within the lumen 104. Moreover, the active cells 160a, 160b of the pressure sensor 150 and those of a pressure sensor fabricated in a different batch (e.g., at a different time, on a different wafer 300) respond similarly or identically to the external pressure of the fluid within the lumen 104. As a result, the sensed pressure is consistent across all of the active cells 160a, 160b in the same batch and across different batches.
One of the challenges in producing a capacitive pressure sensor is reproducibility of the manufacturing method with the same sensor sensitivity from one MEMS batch to another. It is well known that the membranes of capacitive cells at the edge of CMUT arrays suffer from non-uniformities such that edge and corner membranes have different mechanical properties due to processing non-uniformity. The present disclosure advantageously addresses this challenge by providing a spatially compact distribution of capacitive cells within the wafer 300 and/or the die 310. This dense arrangement is made possible by including the dummy cells 164a, 164b, 164c, 164d in between and surrounding the active cells 160a, 160b. For example, the distribution of the dummy cells 164a, 164b, 164c, 164d evenly surrounds the active cells 160a, 160b. This arrangement eliminates the possibility that the active cells 160a, 160b are located at the edge or corners of the die 310 and/or the wafer 300, where the processing non-uniformities arise. If any processing non-uniformities arise, they do so only in the dummy cells 164a, 164b, 164c, 164d, which are not electrically active and are not involved in measuring pressure. The dummy cells 164a, 164b, 164c, 164d provide a uniform surrounding for the active cells 160a, 160b, preventing non-uniform behavior of the active cells 160a, 160b during deposition, lithograpy, and etching steps in the fabrication process, known as proximity effects. The dummy cells 164a, 164b, 164c, 164d are provided to advantageously improve processing uniformity. In that regard, the active cells 160a, 160b are always spaced from the corner or edge of the die 310 and/or the wafer 300 by at least one dummy cell 164a, 164b, 164c, 164d. As shown in
The active cells 160a, 160b are also disposed in a symmetrical environment within the dense arrangement of capacitive cells in the die 310. In that regard, an axis 314 and an axis 316 are shown in
The active cells 160a, 160b are also symmetrically arranged with respect to the dummy cells 164c above and below (e.g., along the axis 316). In the regard, the dummy cells 164c nearest to and above the active cells 160a, 160b (adjacent and/or proximate to a top edge 330 of the pressure sensor 150 in
The symmetrical environment in which the active cells 160a, 160b are fabricated additionally prevents any processing non-uniformities. Both the active cell 160a and the active cell 160b experience the same fabrication steps in their respective vicinities (e.g., the same distances away). As a result, the active cells 160a, 160b respond uniformly to external pressure of the fluid within the lumen 104 of the anatomy 102. The active cells 160a, 160b are also evenly spaced from the top edge 330 and the bottom edge 332 of the pressure sensor 150.
It is well known that lithography, deposition, and etching processes suffer from process non-uniformity and proximity effects. Accordingly, the exact surrounding of the active cells 160a, 160b matters. The thin membrane 168 is also sensitive to these process variabilities. The dummy cells 164a, 164b, 164c, 164d make the MEMS process as uniform as possible, so that the two active cells 160a, 160b behave the same within the pressure sensor 150, but also from die to die and even wafer to wafer. The dummy cells 164a, 164b, 164c, 164d are thus provided for uniformity. As shown in
The active cells 160a, 160b are spaced from one another by a pitch 322. The pitch 322 can be any suitable value in various embodiments. In some embodiments, the pitch 322 can be between approximately 10 μm and approximately 40 μm, between approximately 15 μm and approximately 35 μm, and/or between approximately 22 μm and approximately 26 μm, including values such as 20 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 28 μm, and/or other suitable values both larger and smaller. The pitch 320 (between the dummy cell 164a, 164b and its nearest active cell 160a, 160b) is greater than the pitch 322 (between the active cells). In that regard, the spatially compact distribution of capacitive cells in the die 310 takes into account space for DRIE along the boundary 312. That is, the larger pitch 320 allows for the width of the DRIE lane along the boundary 312 (e.g., between the active cell 160b and the dummy cell 164b to the right of the active cell 160a). To preserve symmetry, the larger pitch 320 is also provided between the active cell 160a and the dummy cell 164a to the left of the active cell 160a. Accordingly, the dummy cells 164a, 164b, 164c, 164d can be positioned close to the active cells 160a, 160b to create a dense arrangement while still leaving space for the size and shape of the pressure sensors 150 to be defined and for the pressure sensors 150 be singulated along the boundary 312 with DRIE. The pitches 320, 322, 324 can be referenced as distances in some instances.
One or more of the dimensions described herein may be accurate within a tolerance of ±10 μm, ±5 μm, ±3 μm, ±2 μm, ±1 μm, and/or other suitable values both larger and smaller. Tolerances of one or more dimensions described herein can be ±36 in some instances.
Persons skilled in the art will also recognize that the apparatus, systems, and methods described above can be modified in various ways. Accordingly, persons of ordinary skill in the art will appreciate that the embodiments encompassed by the present disclosure are not limited to the particular exemplary embodiments described above. In that regard, although illustrative embodiments have been shown and described, a wide range of modification, change, and substitution is contemplated in the foregoing disclosure. It is understood that such variations may be made to the foregoing without departing from the scope of the present disclosure. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 18188185.5 | Aug 2018 | EP | regional |
| 18207789.1 | Nov 2018 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2019/071393 | 8/9/2019 | WO | 00 |
