Fluid coupling media for media isolated pressure sensors

Abstract

An example coupling mechanism for a media isolated pressure sensor, a method for manufacturing a coupling mechanism, and a media isolated pressure sensor are provided. The coupling mechanism includes a fluid coupling medium disposed in the internal cavity of the pressure sensor housing forming a barrier between the pressure sensing circuitry and the fluid. Arrangement of the fluid coupling medium includes dispensing a first portion of a fluid coupling substance within the interior cavity, the first portion of the first portion of the fluid coupling substance having a volume less than a maximum substance volume, and removing dissolved gas from within the first portion. Arrangement of the fluid coupling medium further includes dispensing a second portion of the fluid coupling substance within the interior cavity, the second portion also having a volume smaller than the maximum substance volume. The fluid coupling substance is cured to form a coupling mechanism such that the pressure sensing circuitry generates an electrical signal based on a fluid pressure applied by the fluid through the coupling mechanism.

Description

Technical Field

[0001] Embodiments of the present invention relate generally to media isolated pressure sensors, and more particularly to fabricating a fluid coupling medium for use in a media isolated pressure sensor. Background Art

[0002] Applicants have identified a number of technical challenges and difficulties associated with the manufacture and performance of media-isolated pressure sensors. Through hard work, ingenuity and innovation, Applicants have solved the technical problems associated with fluid coupling media used in media-isolated pressure sensors by developing the technical solutions embodied in the present invention, which will be described in detail below. Summary of the invention

[0003] Various embodiments are directed to example methods and example coupling mechanisms and media isolated pressure sensors utilizing example methods of manufacturing fluid coupling media.

[0004] An example coupling mechanism for a media-isolated pressure sensor is provided. In some embodiments, the coupling mechanism includes: a fluid coupling medium disposed in an interior cavity of a pressure sensor housing, forming a barrier between a pressure sensing circuit system and a fluid medium. The pressure sensing circuit system can be configured to generate an electrical signal based on a fluid medium pressure applied by the fluid medium through the coupling mechanism. In addition, disposing the fluid coupling medium in the interior cavity of the pressure sensor housing includes: dispensing a first portion of a fluid coupling substance in the interior cavity, wherein a first portion volume of the first portion of the fluid coupling substance is less than a maximum fluid coupling substance volume. Disposing the fluid coupling medium in the interior cavity of the pressure sensor housing also includes: removing dissolved gas from within the first portion of the fluid coupling substance; dispensing a second portion of the fluid coupling substance adjacent to the first portion of the fluid coupling substance in the interior cavity, wherein a second portion volume of the second portion of the fluid coupling substance is less than the maximum fluid coupling substance volume, and wherein the interior cavity formed by the pressure sensor housing is substantially filled; removing dissolved gas from within the second portion of the fluid coupling substance; and curing the first portion and the second portion of the fluid coupling substance.

[0005] In some embodiments, the coupling mechanism further comprises a protective coating disposed on a top surface of the fluid coupling medium, wherein the protective coating forms a second barrier between the fluid coupling medium and the fluid medium.

[0006] In some embodiments, the protective coating comprises epoxy.

[0007] In some embodiments, removing dissolved gas from the fluid coupling substance includes exposing the fluid coupling substance to a vacuum environment.

[0008] In some embodiments, curing the first portion of the fluid coupling substance occurs before dispensing the second portion of the fluid coupling substance within the interior cavity.

[0009] In some embodiments, the maximum fluid coupling substance volume is determined based on a cavity ratio of a cavity diameter of the internal cavity to a cavity height of the internal cavity.

[0010] In some embodiments, the maximum void ratio defining the maximum fluid coupling substance volume is between 0.39 and 0.41.

[0011] An example method for manufacturing a coupling mechanism in a media-isolated pressure sensor is also provided. In some embodiments, the method includes dispensing a first portion of a fluid coupling substance in an internal cavity formed by a pressure sensor housing, wherein the fluid coupling substance forms a barrier between a pressure sensing circuit system and a fluid medium, wherein the pressure sensing circuit system is configured to generate an electrical signal based on a fluid medium pressure applied by the fluid medium through the fluid coupling medium, and wherein a first portion volume of the first portion of the fluid coupling substance is less than a maximum fluid coupling substance volume. The method may also include removing dissolved gas from within the first portion of the fluid coupling substance; and dispensing a second portion of the fluid coupling substance adjacent to the first portion of the fluid coupling substance within the pressure sensor housing of the media-isolated pressure sensor, wherein a second portion volume of the second portion of the fluid coupling substance is less than the maximum fluid coupling substance volume, and wherein the internal cavity formed by the pressure sensor housing is substantially filled. The method may also include removing dissolved gas from within the second portion of the fluid coupling substance; and curing the first portion and the second portion of the fluid coupling substance.

[0012] In some embodiments, the method further includes disposing a protective coating on a top surface of the fluid coupling medium, wherein the protective coating forms a second barrier between the fluid coupling medium and the fluid medium.

[0013] In some embodiments, the protective coating comprises an epoxy resin.

[0014] In some embodiments, where the second portion of the fluid coupling substance does not substantially fill the interior cavity formed by the pressure sensor housing, the method further comprises dispensing one or more additional portions of the fluid coupling substance into the interior cavity of the pressure sensor housing, wherein each of the one or more additional portions of the fluid coupling substance has an additional portion volume that is less than a maximum fluid coupling substance volume.

[0015] In some embodiments, the method may further include removing dissolved gas from each of the one or more additional portions of the fluid coupling substance, wherein dispensing the additional portions of the fluid coupling substance and removing dissolved gas are repeated until the interior cavity is substantially full.

[0016] In some embodiments, removing dissolved gas from the fluid coupling substance includes exposing the fluid coupling substance to a vacuum environment.

[0017] In some embodiments, curing a portion of the fluid coupling substance occurs before a subsequent portion of the fluid coupling substance is dispensed within the interior cavity.

[0018] In some embodiments, the maximum fluid coupling substance volume is determined based on a cavity ratio of a cavity diameter of the internal cavity to a cavity height of the internal cavity.

[0019] In some embodiments, the maximum void ratio defining the maximum fluid coupling substance volume is between 0.39 and 0.41.

[0020] An example media-isolated pressure sensor is also provided. In some embodiments, an example media-isolated pressure sensor includes: a pressure sensor housing configured to form an internal cavity; a pressure sensing circuit system disposed within the internal cavity of the pressure sensor housing; and a coupling mechanism including a fluid coupling medium disposed within the internal cavity of the pressure sensor housing. In some embodiments, disposing the fluid coupling medium within the internal cavity of the pressure sensor housing includes: dispensing a first portion of a fluid coupling substance within the internal cavity, wherein a first portion volume of the first portion of the fluid coupling substance is less than a maximum fluid coupling substance volume. Disposing the fluid coupling medium in the interior cavity of the pressure sensor housing may also include: removing dissolved gas from the first portion of the fluid coupling substance; dispensing a second portion of the fluid coupling substance adjacent to the first portion of the fluid coupling substance within the interior cavity, wherein a second portion volume of the second portion of the fluid coupling substance is less than the maximum fluid coupling substance volume, and wherein the interior cavity formed by the pressure sensor housing is substantially filled; removing dissolved gas from the second portion of the fluid coupling substance; and curing the first and second portions of the fluid coupling substance, wherein the fluid coupling medium forms a barrier between the pressure sensing circuitry and the fluid medium, and wherein the pressure sensing circuitry is configured to generate an electrical signal based on a fluid medium pressure applied to the pressure sensing circuitry by the fluid coupling mechanism.

[0021] In some embodiments, the media isolated pressure sensor may further include: a protective coating disposed on a top surface of the fluid coupling medium, wherein the protective coating forms a second barrier between the fluid coupling medium and the fluid medium.

[0022] In some embodiments, the protective coating comprises epoxy.

[0023] In some embodiments, removing dissolved gas from the fluid coupling substance includes exposing the fluid coupling substance to a vacuum environment.

[0024] In some embodiments, curing the first portion of the fluid coupling substance occurs before dispensing the second portion of the fluid coupling substance within the interior cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Reference will now be made to the drawings. The components shown in the drawings may or may not be present in certain embodiments described herein. Some embodiments may include fewer (or more) components than those shown in the drawings according to example embodiments of the present invention.

[0026] Figure 1A cross section of an example media-isolated sensor having a fluid coupling medium with entrapped dissolved gas is shown.

[0027] Figure 2 A cross section of an example media isolated pressure sensor having a first portion of a fluid coupling substance is shown according to an example embodiment of the present invention.

[0028] Figure 3 A cross section of an example media isolated pressure sensor having a second portion of a fluid coupling substance is shown according to an example embodiment of the present invention.

[0029] Figure 4 A cross section of an example protective coating protecting a fluid coupling medium according to an example embodiment of the present invention is shown.

[0030] Figure 5 An example process for fabricating a fluid coupling medium in a media-isolated pressure sensor according to an example embodiment of the present invention is shown. DETAILED DESCRIPTION

[0031] Example embodiments will be described more fully below with reference to the accompanying drawings, in which some but not all embodiments of the present invention of the present disclosure are shown. Indeed, embodiments of the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present invention will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0032] Various example embodiments address technical issues associated with coupling external pressure or force from a fluid medium (e.g., liquid or gas) to pressure sensing circuitry in a media-isolated pressure sensor. As will be appreciated by those skilled in the art, there are a variety of situations in which high-precision pressure and / or force may be measured while maintaining isolation between the pressure sensing circuitry and the fluid medium exhibiting the pressure.

[0033] Generally speaking, a pressure sensor is a transducer device designed to generate an electrical signal based on the pressure applied to the pressure sensing circuitry. In many applications, flush mount pressure sensors are used to measure the pressure of a fluid medium. Flush mount pressure sensors are designed to be installed in a pipe or other conduit carrying a fluid medium. A media isolated pressure sensor may be required to form a barrier between the measured fluid medium and the pressure sensing circuitry of the media isolated pressure sensor.

[0034] For example, medical personnel may wish to measure a patient's blood pressure through an IV line. In this case, portions of the media-isolated pressure sensor may be inserted directly into the IV line or other conduit carrying the patient's blood. To comply with medical standards, it may be important that the pressure sensing circuitry remain isolated from the patient's bodily fluids and the intravenous fluids being administered. Additionally, isolation from the pressure sensing circuitry may be required to prevent short circuits and otherwise ensure proper operation of the pressure sensor.

[0035] In addition, certain fluid media may damage the pressure sensing circuit system and other components of the pressure sensor. Such fluid media may include blood, saline, coffee, gasoline, engine oil, and other similar fluids. In some embodiments, such fluid media may be isolated from the pressure sensing circuit system and other components of the pressure sensor to protect the internal components of the pressure sensor from exposure to the fluid media. Pressure sensors that employ a mechanism to separate the pressure sensing circuit system from the measured fluid medium are referred to herein as media-isolated pressure sensors.

[0036] In order to isolate the fluid medium from the electrical components of the media-isolated pressure sensor while still being able to receive applied pressure from the fluid medium, a coupling mechanism is allocated into the internal cavity of the pressure sensor housing, the coupling mechanism including a fluid coupling substance, such as a protective gel. The fluid coupling substance encapsulates the pressure sensing circuit system, protecting the circuit system during the fluid medium measurement. The fluid coupling substance ensures that no fluid contacts the pressure sensing circuit system of the media-isolated pressure sensor, thereby protecting the pressure sensing circuit system from damage by the fluid medium and complying with medical standards.

[0037] In addition, the fluid coupling substance acts as a fluid coupling medium, transmitting the pressure exhibited by the fluid medium to the pressure sensing component (e.g., the pressure sensing diaphragm) of the pressure sensing circuit system. Therefore, the fluid coupling medium (including the fluid coupling substance) enables the pressure sensing circuit system to measure the pressure of the fluid medium.

[0038] Various methods used to fill the internal cavity of the pressure sensor housing result in pockets of dissolved gas (e.g., bubbles) being created in the fluid coupling material. Dissolved gas in the fluid coupling medium can adversely affect the performance of the media-isolated pressure sensor, resulting in inaccurate and inconsistent pressure measurements. The adverse effects of dissolved gas are exacerbated in situations where the media-isolated pressure sensor is exposed to high temperatures, such as where the media-isolated pressure sensor is soldered to a supporting circuit board. In such situations, the dissolved gas expands, increasing the size of the trapped bubbles. During the manufacturing process, vacuum methods are often used to squeeze the dissolved gas out of the fluid coupling material, however, these methods are largely ineffective for larger volumes of fluid coupling material. In addition, many media-isolated pressure sensors are used in high-pressure environments with abrasive fluid media. In such situations, the fluid media may damage and erode the fluid coupling medium over time, further reducing the accuracy and consistency of the media-isolated pressure sensor.

[0039] Various example embodiments described herein utilize various techniques to form a coupling mechanism in a media isolated pressure sensor. For example, in some embodiments, a multi-step process is utilized to dispose a fluid coupling substance in an interior cavity of a pressure sensor housing. The first step includes injecting a portion of the fluid coupling substance such that it does not exceed a maximum fluid coupling substance volume. The injected fluid coupling substance may then be exposed to a vacuum environment to evacuate any dissolved gas in the first portion of the fluid coupling substance. Additionally, once the dissolved gas is evacuated, the first portion of the fluid coupling substance may optionally be cured.

[0040] Subsequent steps may include injecting the second portion of the fluid coupling substance so as not to exceed the maximum fluid coupling substance volume. The injected second portion of the fluid coupling substance may then be exposed to a vacuum environment to evacuate any dissolved gas in the second portion of the fluid coupling substance. This process may continue until the interior cavity of the pressure sensor housing is substantially full and capable of producing accurate pressure sensing measurements.

[0041] Additionally, in some embodiments disclosed herein, a protective coating can be dispensed on the top surface of the fluid coupling medium. The protective coating can be cured such that the protective coating exhibits increased hardness compared to the fluid coupling medium. Thus, the protective coating provides robust protection against harsh fluid medium applications. While the top layer exhibits increased hardness, the inner fluid coupling medium remains relatively soft, thereby providing the transmission characteristics needed to accurately determine the pressure in the fluid medium.

[0042] As a result of the example embodiments described herein and in some examples, the accuracy and effectiveness of a media isolated pressure sensor can be greatly improved. Additionally, the resilience and continued accuracy of the media isolated pressure sensor can be maintained over time.

[0043] Reference now Figure 1 , an example media isolated pressure sensor 100 is provided. Figure 1 As shown in , the example media-isolated pressure sensor 100 includes a pressure sensor housing 108 extending from a substrate 110 to form an internal cavity 118. The example media-isolated pressure sensor 100 also includes a pressure sensing circuit system 104 attached to the substrate 110, opposite the open end of the internal cavity 118. The internal cavity 118 is filled with a fluid coupling medium 102. Figure 1 As shown in , the fluid coupling medium 102 includes a dissolved gas 116, which forms a plurality of gas pockets or bubbles in the fluid coupling medium 102. Figure 1 As further shown in FIG. 1 , the pressure sensor housing 108 is inserted into a fluid conduit 112 carrying a fluid medium 114 . The pressure of the fluid medium 114 is transmitted through the fluid coupling medium 102 and received by the pressure sensing circuit system 104 .

[0044] like Figure 1 As shown in , the example media isolated pressure sensor 100 includes a pressure sensor housing 108 attached to a substrate 110 to form an internal cavity 118. The substrate 110 is any structure configured to support the attachment of the pressure sensing circuitry 104 components and the pressure sensor housing 108. In some embodiments, the substrate 110 may include a printed circuit board (PCB) or ceramic alumina that includes electrical connections to connect the pressure sensing circuitry to a processor, a controller, an analog-to-digital converter, or other electrical components.

[0045] like Figure 1 As further shown in FIG. 1 , the example media-isolated pressure sensor 100 includes a pressure sensor housing 108. The pressure sensor housing 108 may be any structure, wall, or multiple walls configured to form a partially enclosed interior cavity 118 with the substrate 110. The pressure sensor housing 108 is configured to enclose the pressure sensing circuit system 104 within the interior cavity 118 of the pressure sensor housing 108. Figure 1 As shown in , the pressure sensor housing 108 can have a circular tubular shape (characterized by a diameter and a height), although other configurations may be suitable for certain embodiments. For example, the pressure sensor housing 108 can have a rectangular cross-section (having four side walls), a triangular cross-section (having three side walls), a hexagonal cross-section (having six side walls), and / or the like.

[0046] In some embodiments, the pressure sensor housing 108 may further include a sealing structure around the outer surface of one or more side walls of the pressure sensor housing 108 for forming a seal between the media isolated pressure sensor 100 and the fluid conduit 112. The sealing structure (e.g., a port) may secure the media isolated pressure sensor 100 within the fluid conduit 112 and ensure that the fluid medium 114 does not leak at the interface between the fluid conduit 112 and the media isolated pressure sensor 100.

[0047] like Figure 1 As further shown in FIG. 1 , the example media-isolated pressure sensor 100 includes a pressure sensing circuit system 104 attached to the substrate 110 in the internal cavity 118, opposite the open end of the internal cavity 118. The pressure sensing circuit system 104 is any circuit system configured to generate an electrical signal based on the pressure applied to the sensing surface of the pressure sensing circuit system 104. In some embodiments, the pressure sensing circuit system 104 may include a pressure sensing diaphragm. The pressure sensing diaphragm may be formed of a semiconductor material configured to deform under pressure applied to the surface of the pressure sensing diaphragm. In some embodiments, the pressure sensing diaphragm may include a piezoresistive sensor arranged in a Wheatstone bridge circuit so that the pressure and deflection on the pressure sensing diaphragm produces a resistance change in the arranged sensor and a voltage output related to the applied force. In some embodiments, the pressure sensing diaphragm may be placed over an opening that allows the pressure sensing diaphragm to deflect in a certain manner so that the change in the electrical characteristics of the pressure sensing diaphragm represents the applied pressure.

[0048] In addition to the pressure sensing diaphragm, the pressure sensing circuit system 104 may include a pressure sensing die. The pressure sensing die may include electrical components configured to be electrically connected to the pressure sensing diaphragm and monitor changes in the resistivity of the pressure sensing diaphragm based on the pressure applied to the surface of the pressure sensing diaphragm by the fluid coupling medium 102. The pressure sensing chip may include a converter, hardware components, processor, or other electronic components configured to help convert the pressure applied to the pressure sensing diaphragm into an electrical signal. The electrical signal representing the pressure applied to the pressure sensing diaphragm may be transmitted to one or more conductive components on the substrate 110 via one or more wire bonds 106.

[0049] In some embodiments, the pressure sensing circuitry may be electrically connected to the substrate 110 via through-hole connectors that pass through the substrate 110, such that an output signal resulting from pressure applied to the pressure sensing circuitry 104 is transmitted from the pressure sensing circuitry 104 through the substrate 110 to conductive elements on the opposite side of the substrate 110. By passing the electrical connections through the through-hole connectors of the substrate 110 and making the electrical connections outside of the internal cavity 118, the electrical connections and soldered components of the pressure sensing circuitry 104 may be protected from damage or shorts caused by pressure applied to the fluid coupling medium 102.

[0050] like Figure 1 As further shown in FIG. 1 , the example media-isolated pressure sensor 100 includes a fluid coupling medium 102 that substantially fills an interior cavity 118 to provide a coupling mechanism between a pressure sensing circuit system 104 and a fluid medium 114 in a fluid conduit 112. The fluid coupling medium may include any incompressible fluid coupling material configured to provide a fluid coupling between the fluid medium 114 and the pressure sensing circuit system 104. In some embodiments, the fluid coupling medium may include a gel fluid coupling material such as silicone. Figure 1 , the fluid coupling medium 102 is deformed to substantially cover the surface of the pressure sensing circuit system 104. In addition, the fluid coupling medium 102 substantially fills the interior cavity 118 of the pressure sensor housing 108, such that the fluid coupling medium 102 is substantially flush with the top of the pressure sensor housing. By substantially filling the pressure sensor housing 108 with the fluid coupling medium 102, the pressure applied by the fluid medium 114 in the fluid conduit 112 can be more accurately transmitted to the pressure sensing circuit system 104.

[0051] like Figure 1 As further shown in FIG. 1 , the media-isolated pressure sensor 100 is attached to a fluid conduit 112 containing a fluid medium 114 such that the fluid coupling medium 102 is in contact with the fluid medium 114. The fluid conduit 112 may be any pipe, duct, tube, or other conduit configured to enable the fluid medium 114 to flow within the fluid conduit 112. In some embodiments, the fluid conduit 112 may include an IV line carrying a patient's blood or other bodily fluids, a catheter, a gas line enabling gasoline to flow, or any other fluid line configured to enable the flow of a fluid or gas.

[0052] The fluid medium 114 may be any liquid or gas contained within the fluid conduit 112. In some embodiments, the fluid medium 114 may include blood, body fluids, saline, coffee, gasoline, motor oil, oxygen, methane, carbon dioxide, and other similar fluids. The fluid medium 114 may exhibit a pressure within the fluid conduit 112. The pressure may be exhibited based on the operation of a body organ (e.g., a heart pumping blood), a mechanical device (e.g., an air pump), an inflow of additional fluid medium 114, or from any other source. Figure 1 As shown in , the fluid coupling medium 102 of the media-isolated pressure sensor 100 is positioned within the fluid conduit 112 such that the fluid medium 114 is in contact with the fluid coupling medium 102. Therefore, the pressure of the fluid medium 114 is exerted on the fluid coupling medium 102. The fluid coupling medium 102 is fluidically coupled to the pressure sensing circuit system 104, and therefore, the pressure of the fluid medium 114 is transmitted to the pressure sensing circuit system 104 through the fluid coupling medium 102.

[0053] Additionally, the fluid coupling medium 102 forms a barrier between the pressure sensing circuit system 104 and the fluid medium 114. In the event that the fluid medium 114 comes into contact with the pressure sensing circuit system 104, the fluid medium 114 may damage electrical components of the pressure sensing circuit system 104. Additionally, contact with the pressure sensing circuit system 104 may result in a short circuit or other catastrophic failure. Thus, the fluid coupling medium 102 is used to create a barrier that the fluid medium 114 cannot penetrate. Instead, the pressure of the fluid medium 114 is transmitted to the pressure sensing circuit system 104 through the fluid coupling through the fluid coupling medium 102.

[0054] like Figure 1As further shown in FIG. 1 , the fluid coupling medium 102 may include dissolved gas 116. In some approaches, a fluid coupling substance (e.g., silica gel) containing the fluid coupling medium 102 may be mixed and deposited in an interior cavity 118 of the pressure sensor housing 108. Using such an approach may result in the capture of dissolved gas 116 within the fluid coupling substance. The dissolved gas 116 within the fluid coupling substance may adversely affect the operation of the media isolated pressure sensor 100. For example, the dissolved gas 116 within the fluid coupling medium 102 may result in inconsistent pressure measurements based on the pressure exerted on the surface of the fluid coupling medium 102 by the fluid medium 114. The adverse effects may be exacerbated in the presence of heat, such as in the case where the media isolated pressure sensor 100 is soldered to an underlying circuit board. In the presence of heat, the dissolved gas 116 within the fluid coupling medium 102 may expand to form pockets of dissolved gas 116 that increase in size. The presence of pockets or bubbles of dissolved gas 116 in the fluid coupling medium 102 may have a significant impact on the accuracy and consistency of the media isolated pressure sensor 100. The embodiments described as part of the present invention significantly reduce the presence of dissolved gas 116 and resulting gas bubbles in the fluid coupling medium 102 .

[0055] Reference now Figure 2 , depicting an example media isolated pressure sensor 200. The example media isolated pressure sensor 200 includes a pressure sensor housing 208 that includes a wall extending from a substrate 210 and forming a closed perimeter around an internal cavity 218. The internal cavity 218 is surrounded by the substrate 210 at one end, surrounded by the pressure sensor housing 208 at the sides, and open at the end opposite the substrate 210. Figure 2 , the internal cavity 218 has a cavity diameter 222 and a cavity height 224. The pressure sensing circuitry 204 is shown attached to the substrate 210 within the internal cavity 218. Additionally, a first portion of a fluid coupling substance 220 is shown that partially fills the internal cavity 218 of the media isolated pressure sensor 200.

[0056] like Figure 2 As shown in , a first portion of the fluid coupling substance 220 is dispensed into the interior cavity 218 formed by the pressure sensor housing 208. Figure 1 As depicted, the first portion of fluid coupling substance 220 may include any incompressible fluid configured to provide fluid coupling between the fluid medium and pressure sensing circuitry 204. For example, the first portion of fluid coupling substance 220 may include a gel fluid coupling substance such as silicone.

[0057] During the mixing and dispensing process, dissolved gases (e.g., dissolved gas 116) may be trapped in the fluid coupling substance. The dissolved gases may expand into bubbles, thereby adversely affecting the performance of the media isolated pressure sensor 200. Therefore, the media isolated pressure sensor having the fluid coupling substance may be exposed to a vacuum environment to remove the dissolved gases trapped within the fluid coupling substance. However, when the volume of the fluid coupling substance is large, vacuum techniques become less effective in removing dissolved gases.

[0058] To prevent the formation of dissolved gas pockets, a maximum fluid coupling material volume is determined to limit the amount of fluid coupling material dispensed into the interior cavity 218 prior to evacuating the dispensed fluid coupling material. The maximum fluid coupling material volume may be determined based on a variety of factors, including, but not limited to, the composition of the fluid coupling material, the size of the interior cavity 218, the vacuum technology utilized, the curing process, and other factors. For example, in the case of using silicone as the fluid coupling material, the maximum fluid coupling material volume of the silicone dispensed prior to evacuating the dissolved gases may be based on the weight of the silicone. In some embodiments, the maximum fluid coupling material volume of the silicone may be between 28 and 42 milligrams; more preferably between 30 and 40 milligrams; and most preferably between 34 and 36 milligrams.

[0059] In some embodiments, the maximum fluid coupling substance volume may be based on the physical dimensions of the interior cavity 218. Figure 2 As shown in , the internal cavity 218 includes a cavity diameter 222 and a cavity height 224. The effectiveness of removing dissolved gases from the fluid coupling substance may depend on the physical dimensions of the internal cavity 218. For example, in some embodiments, the internal cavity 218 may have a wide cavity diameter 222 but a shallow cavity height 224. The amount of fluid coupling substance required to fill the internal cavity 218 may be large, and for internal cavities of such size, vacuum techniques for removing dissolved gases may be effective. Therefore, the maximum fluid coupling substance volume may be based on a cavity ratio, where the cavity ratio is determined based on the ratio of the cavity height 224 to the cavity diameter 222. In some embodiments, the maximum fluid coupling substance volume may be between 0.35 and 0.45; more preferably between 0.37 and 0.43; and most preferably between 0.39 and 0.41. Although the pressure sensor housing 208 is depicted as having a circular cross-section, the maximum fluid coupling substance volume may be similarly determined based on the cavity ratio of any cross-sectional shape of the pressure sensor housing 208.

[0060] Reference now Figure 3, depicting an example media isolated pressure sensor 300. The example media isolated pressure sensor 300 includes a pressure sensor housing 308 that includes walls extending from a substrate 310 and forming a closed perimeter around an internal cavity 318. The internal cavity 318 is surrounded by the substrate 310 at one end, surrounded by the pressure sensor housing 308 at the sides, and open at the end opposite the substrate 310. The pressure sensing circuit system 304 is shown attached to the substrate 310 within the internal cavity 318. Figure 3 As further shown in FIG. 3 , the second portion 330 of the fluid coupling substance is dispensed on top of the first portion 320 of the fluid coupling substance, filling the interior cavity 318 of the media isolated pressure sensor 300 .

[0061] like Figure 3 As shown in FIG. 1 , the example media isolated pressure sensor 300 includes a second portion 330 of a fluid coupling substance dispensed on a top surface 320a of a first portion 320 of a fluid coupling substance. Figure 1 As described, the second portion 330 of the fluid coupling substance may include any incompressible fluid configured to provide a fluid coupling between the fluid medium and the pressure sensing circuit system 304. For example, the second portion 330 of the fluid coupling substance may include a gel fluid coupling substance, such as silicone. In some embodiments, the second portion 330 of the fluid coupling substance may be the same substance as the first portion 320 of the fluid coupling substance.

[0062] like Figure 3 As shown in , the second portion 330 of the fluid coupling substance can be dispensed until the second portion 330 of the fluid coupling substance is flush with the top of the side wall of the pressure sensor housing 308. Figure 3 As shown in FIG. 3 , the first portion 320 of the fluid coupling substance and the second portion 330 of the fluid coupling substance together form the fluid coupling medium 302. Any pressure applied by the fluid medium to the second portion 330 of the fluid coupling substance is transmitted to the pressure sensing circuit system 304 through the second portion 330 of the fluid coupling substance and the adjacent first portion 320 of the fluid coupling substance.

[0063] In some cases, the volume of fluid coupling substance required to fill the remainder of interior cavity 318 may exceed the maximum fluid coupling substance volume. In such cases, the volume of second portion 330 of fluid coupling substance is limited to be less than the maximum fluid coupling substance volume. Thus, second portion 330 of fluid coupling substance may be deposited and dissolved gases removed before additional portions of fluid coupling substance are added as needed.

[0064] As about Figure 2As described, the maximum fluid coupling substance volume may be determined based on the volume or mass of the fluid coupling substance. Thus, in the event that the mass or volume of fluid coupling substance required to fill the remainder of the interior cavity 318 exceeds the maximum fluid coupling substance volume, the fluid coupling substance may require one or more additional portions to be added to the interior cavity after the second portion 330 of the fluid coupling substance.

[0065] As about Figure 2 As further described, the maximum fluid coupling substance volume can be determined based on the physical dimensions of the interior cavity 318 defined by the pressure sensor housing 308. Once the first portion 320 of the fluid coupling substance is dispensed into the interior cavity 318, a remaining cavity height 332 from the top surface 320a of the first portion 320 of the fluid coupling substance can be defined. The remaining cavity height 332 is the distance from the top surface 320a of the first portion 320 of the fluid coupling substance to the upper extent of the sidewall of the pressure sensor housing 308. A cavity ratio and a cavity diameter (e.g., cavity diameter 222) can be determined based on the remaining cavity height 332. In the event that the cavity ratio exceeds the maximum cavity ratio defined by the maximum fluid coupling substance volume, one or more additional portions of the fluid coupling substance can be added to the interior cavity after the second portion 330 of the fluid coupling substance.

[0066] Reference now Figure 4 , an example media-isolated pressure sensor 400 is provided. Figure 4 As shown in FIG. 1 , an example media-isolated pressure sensor 400 includes a fluid coupling medium 402 including a first portion of a fluid coupling substance 420 and a second portion of a fluid coupling substance 430. The fluid coupling medium 402 is deposited within an interior cavity 418 of the media-isolated pressure sensor 400, which is formed by a substrate 410 and one or more walls including a pressure sensor housing 408 extending from the substrate 410. Figure 4 As further shown in FIG. 4 , a protective coating 440 is deposited on the top surface 430 a of the fluid coupling medium 402 .

[0067] like Figure 4 As shown in FIG. 4 , a protective coating 440 is deposited on a top surface 430a of a second portion of the fluid coupling substance 430. In some embodiments, the fluid coupling medium of the media-isolated pressure sensor 400 is exposed to an abrasive fluid medium and / or a high pressure environment. The fluid medium in such an environment may bombard the fluid coupling substance including the fluid coupling medium 402. The fluid coupling medium 402 may be damaged or corroded under such conditions. A damaged or corroded fluid coupling medium 402 may adversely affect the performance of the media-isolated pressure sensor 400.

[0068] The protective coating 440 may be any substance disposed between the fluid coupling medium 402 and the fluid medium that applies pressure to the media-isolated pressure sensor 400 that is configured to protect the fluid coupling medium 402 while still allowing transmission of pressure through the fluid coupling medium 402 to the pressure sensing circuit system 404. In some embodiments, the protective coating 440 may include an epoxy. The epoxy protective coating 440 may provide a hard layer compared to the fluid coupling medium 402 while the fluid coupling medium 402 remains relatively soft. Thus, the harder protective coating 440 provides protection from harsh environments and fluid mediums while still providing the desired fluid transmission medium from the fluid medium to the pressure sensing circuit system 404.

[0069] Reference now Figure 5 An example process 500 for manufacturing a fluid coupling medium (e.g., fluid coupling medium 102, 302, 402) is provided. At block 502, a first portion of a fluid coupling substance (e.g., fluid coupling substance 220, 320, 420) is dispensed into an interior cavity (e.g., interior cavity 118, 218, 318, 418) formed by a pressure sensor housing (e.g., pressure sensor housing 108, 208, 308, 408), wherein the fluid coupling substance forms a barrier between pressure sensing circuitry (e.g., pressure sensing circuitry 104, 204, 304, 404) and a fluid medium (e.g., fluid medium 114), wherein the pressure sensing circuitry is configured to generate an electrical signal based on a fluid medium pressure applied by the fluid medium through the fluid coupling medium, and wherein a first portion volume of the first portion of the fluid coupling substance is less than a maximum fluid coupling substance volume. As described herein, the maximum fluid coupling substance volume can be determined based on the fluid coupling substance used to create the fluid coupling medium, the size of the internal cavity, the vacuuming technique used, the curing procedure used, and other similar factors. In some embodiments, the volume of fluid coupling substance required to fill the internal cavity of the media isolated pressure sensor can exceed the maximum fluid coupling substance volume. In this case, the amount of fluid coupling substance disposed in the internal cavity of the media isolated pressure sensor is less than the maximum fluid coupling substance volume.

[0070] In some embodiments, the maximum fluid coupling substance volume can be based on a cavity ratio, which is determined based on the ratio of the cavity height (or the height of the fluid coupling substance within the cavity) to the cavity diameter. In this case, the maximum height can be determined based on the cavity diameter. For example, if the maximum fluid coupling substance volume is 0.4 and the cavity diameter is 10 mm, the height of the fluid coupling substance may not exceed 4 mm. Therefore, the maximum height of the fluid coupling substance in the interior cavity is 4 mm. In this case, the height of the first portion of the fluid coupling substance does not exceed 4 mm.

[0071] At block 504, dissolved gas (e.g., dissolved gas 116) is removed from within the first portion of the fluid coupling substance. The dissolved gas may be removed by any method designed to expel trapped gas from within the fluid coupling substance. For example, a media isolated pressure sensor including a partially filled internal cavity may be exposed to a vacuum environment. The vacuum environment may expel any dissolved gas within the fluid coupling substance. In some embodiments, the vacuum degassing process may utilize a vacuum environment at a pressure of 0.04 millibar or less, wherein the media isolated pressure sensor is exposed to the vacuum environment for 15 minutes or about 15 minutes.

[0072] In some embodiments, after venting dissolved gas from the first portion of the fluid coupling substance and before adding an additional portion of the fluid coupling substance to the interior cavity, the first portion of the fluid coupling substance can be cured.

[0073] At block 506, a second portion of a fluid coupling substance (e.g., fluid coupling substance 330, 430) is dispensed within a pressure sensor housing of the media isolated pressure sensor, adjacent to the first portion of the fluid coupling substance, wherein a second portion volume of the second portion of the fluid coupling substance is less than a maximum fluid coupling substance volume, and wherein an interior cavity formed by the pressure sensor housing is substantially filled. As described herein, the second portion of the fluid coupling substance is deposited in the interior cavity on a top surface of the first portion of the fluid coupling substance. Depositing the second portion of the fluid coupling substance is still subject to the constraints established by the maximum fluid coupling substance volume. In the event that the interior cavity of the media isolated pressure sensor can be substantially filled without exceeding the maximum fluid coupling substance volume, sufficient fluid coupling substance is added to substantially fill the interior cavity. In the event that the required volume of the fluid coupling substance required to substantially fill the interior cavity exceeds the maximum fluid coupling substance volume, the second portion of the fluid coupling substance is disposed into the interior cavity and dissolved gas is removed from the second portion of the fluid coupling substance, after which an additional portion of the fluid coupling substance may be added.

[0074] In some embodiments, the maximum fluid coupling substance volume may be based on a cavity ratio, which is determined based on a ratio of the cavity height (or the remaining cavity height in the internal cavity) to the cavity diameter. If the remaining cavity height in the internal cavity exceeds the maximum height determined based on the maximum cavity ratio, an additional portion of the fluid coupling substance may be required to fill the internal cavity.

[0075] At block 508, dissolved gas is removed from the second portion of the fluid coupling substance. The dissolved gas in the second portion of the fluid coupling substance may be removed by any method designed to expel trapped gas from within the fluid coupling substance. For example, the media isolated pressure sensor including a partially filled internal cavity may be exposed to a vacuum environment. The vacuum environment may expel any dissolved gas within the fluid coupling substance. In some embodiments, the vacuum degassing process may utilize a vacuum environment at a pressure of 0.04 millibar or less, wherein the media isolated pressure sensor is exposed to the vacuum environment for 15 minutes or about 15 minutes.

[0076] At block 510, the first and second portions of the fluid coupling substance are cured. The fluid coupling substance may be cured to be fully cured and properly function as a coupling mechanism in a media isolated pressure sensor. For example, where silicone is used as the fluid coupling substance, the silicone may be cured by standing at room temperature for a specific amount of time and / or by exposing the silicone to heat. All portions of the fluid coupling substance may be cured simultaneously, or in some embodiments, each portion of the fluid coupling substance may be cured separately.

[0077] Thanks to the teachings presented in the foregoing description and the related drawings, those skilled in the art to which the present invention belongs will think of many modifications and other embodiments of the present invention set forth herein. Although the drawings show only certain components of the apparatus and system described herein, it should be understood that various other components may be used in conjunction with the system. Therefore, it should be understood that the present invention is not limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the appended claims. In addition, the steps in the above-described method do not necessarily occur in the order depicted in the drawings, and in some cases, one or more of the depicted steps may occur substantially simultaneously, or may involve additional steps. Although specific terms are used herein, they are used only in a general and descriptive sense, and not for purposes of limitation.

[0078] Although various embodiments according to the principles disclosed herein have been shown and described above, modifications may be made thereto by those skilled in the art without departing from the spirit and teachings of the invention. The embodiments described herein are representative only and are not intended to be limiting. Many variations, combinations and modifications are possible and are within the scope of the invention. The disclosed embodiments are primarily directed to media-isolated pressure sensors, however, those skilled in the art will recognize that such principles may be applied to any application in which a fluid coupling substance such as silicone is used as a fluid coupling medium. Alternative embodiments resulting from combining, integrating and / or omitting features of the embodiments are also within the scope of the invention. Therefore, the scope of protection is not limited by the above description.

[0079] Additionally, the section headings used herein are provided to be consistent with the recommendations under 37 CFR 1.77 or to otherwise provide an organizational cue. Such headings shall not limit or characterize the inventions set forth in any claims that may be filed herein.

[0080] The use of broader terms such as "comprises," "includes," and "having" should be understood to provide support for narrower terms such as "consisting of," "consisting essentially of," and "consisting essentially of." The use of the terms "optionally," "may," "might," "possibly," and the like with respect to any element of an embodiment means that the element is not required or, alternatively, the element is required, both alternatives being within the scope of the embodiment. Furthermore, references to examples are provided for illustrative purposes only and are not intended to be exclusive.

Claims

1. A coupling mechanism for a medium-isolated pressure sensor, the coupling mechanism comprising: a fluid coupling medium disposed within the interior cavity of the pressure sensor housing to form a barrier between the pressure sensing circuitry and the fluid medium, wherein the pressure sensing circuit system is configured to generate an electrical signal based on a fluid medium pressure applied by the fluid medium through the coupling mechanism, and Wherein disposing the fluid coupling medium in the internal cavity of the pressure sensor housing comprises: dispensing a first portion of a fluid coupling substance within the interior cavity, wherein a first portion volume of the first portion of the fluid coupling substance is less than a maximum fluid coupling substance volume; removing dissolved gas from within the first portion of the fluid coupling substance; dispensing a second portion of the fluid coupling substance within the interior cavity adjacent to the first portion of the fluid coupling substance, wherein a second portion volume of the second portion of the fluid coupling substance is less than the maximum fluid coupling substance volume, and wherein said interior cavity formed by said pressure sensor housing is substantially filled; removing dissolved gas from within the second portion of the fluid coupling substance; and The first portion and the second portion of the fluid coupling substance are cured.

2. The coupling mechanism of claim 1, further comprising a protective coating disposed on a top surface of the fluid coupling medium, wherein the protective coating forms a second barrier between the fluid coupling medium and the fluid medium.

3. The coupling mechanism of claim 2, wherein the protective coating comprises epoxy.

4. The coupling mechanism of claim 1, wherein removing dissolved gas from the fluid coupling substance comprises exposing the fluid coupling substance to a vacuum environment.

5. The coupling mechanism of claim 1, wherein curing the first portion of the fluid coupling substance occurs before the second portion of the fluid coupling substance is dispensed within the interior cavity.

6. The coupling mechanism of claim 1, wherein the maximum fluid coupling substance volume is determined based on a cavity ratio of a cavity diameter of the internal cavity to a cavity height of the internal cavity.

7. The coupling mechanism of claim 6, wherein a maximum cavity ratio defining the maximum fluid coupling substance volume is between 0.39 and 0.

41.

8. A method for manufacturing a coupling mechanism in a media-isolated pressure sensor, the method comprising: dispensing a first portion of a fluid coupling substance within an interior cavity formed by the pressure sensor housing, wherein the fluid coupling substance forms a barrier between the pressure sensing circuitry and the fluid medium, and wherein a first portion volume of the first portion of the fluid coupling substance is less than a maximum fluid coupling substance volume; removing dissolved gas from within the first portion of the fluid coupling substance; dispensing a second portion of the fluid coupling substance adjacent to the first portion of the fluid coupling substance within the pressure sensor housing of the media isolated pressure sensor, wherein a second portion volume of the second portion of the fluid coupling substance is less than the maximum fluid coupling substance volume, and wherein said interior cavity formed by said pressure sensor housing is substantially filled; removing dissolved gas from within the second portion of the fluid coupling substance; and curing the first portion and the second portion of the fluid coupling substance, The pressure sensing circuit system is configured to generate an electrical signal based on a fluid medium pressure applied by the fluid medium through the coupling mechanism.

9. The method of claim 8, further comprising: A protective coating is disposed on a top surface of the fluid coupling medium, wherein the protective coating forms a second barrier between the fluid coupling medium and the fluid medium.

10. The method of claim 9, wherein the protective coating comprises an epoxy resin.

11. The method of claim 8, wherein in a case where the second portion of the fluid coupling substance does not substantially fill the interior cavity formed by the pressure sensor housing, the method further comprises: dispensing one or more additional portions of the fluid coupling substance within the interior cavity of the pressure sensor housing, wherein each of the one or more additional portions of the fluid coupling substance has an additional portion volume that is less than a maximum fluid coupling substance volume; and removing dissolved gas from each of the one or more additional portions of the fluid coupling substance, Wherein dispensing the additional portion of the fluid coupling substance and removing the dissolved gas are repeated until the interior cavity is substantially full.

12. The method of claim 8, wherein removing dissolved gas from the fluid coupling substance comprises exposing the fluid coupling substance to a vacuum environment.

13. The method of claim 8, wherein curing the portion of the fluid coupling substance occurs before a subsequent portion of the fluid coupling substance is dispensed within the interior cavity.

14. The method of claim 8, wherein the maximum fluid coupling substance volume is determined based on a cavity ratio of a cavity diameter of the internal cavity to a cavity height of the internal cavity.

15. The method of claim 14, wherein a maximum void ratio defining the maximum fluid coupling substance volume is between 0.39 and 0.

41.

16. A media-isolated pressure sensor, comprising: a pressure sensor housing configured to form an internal cavity; a pressure sensing circuit system disposed within the interior cavity of the pressure sensor housing; as well as A coupling mechanism comprising a fluid coupling medium disposed in the interior cavity of the pressure sensor housing, wherein disposing the fluid coupling medium in the interior cavity of the pressure sensor housing comprises: dispensing a first portion of a fluid coupling substance within the interior cavity, wherein a first portion volume of the first portion of the fluid coupling substance is less than a maximum fluid coupling substance volume; removing dissolved gas from within the first portion of the fluid coupling substance; dispensing a second portion of the fluid coupling substance within the interior cavity adjacent to the first portion of the fluid coupling substance, wherein a second portion volume of the second portion of the fluid coupling substance is less than the maximum fluid coupling substance volume, and wherein said interior cavity formed by said pressure sensor housing is substantially filled; removing dissolved gas from within the second portion of the fluid coupling substance; and curing the first portion and the second portion of the fluid coupling substance, wherein the fluid coupling medium forms a barrier between the pressure sensing circuitry and the fluid medium, and The pressure sensing circuit system is configured to generate an electrical signal based on a fluid medium pressure applied to the pressure sensing circuit system through the fluid coupling mechanism.

17. The media isolated pressure sensor of claim 16, further comprising a protective coating disposed on a top surface of the fluid coupling medium, wherein the protective coating forms a second barrier between the fluid coupling medium and the fluid medium.

18. The media isolated pressure sensor of claim 17, wherein the protective coating comprises an epoxy.

19. The media isolated pressure sensor of claim 16, wherein removing dissolved gas from the fluid coupling substance comprises exposing the fluid coupling substance to a vacuum environment.

20. The media isolated pressure sensor of claim 16, wherein curing the first portion of the fluid coupling substance occurs before dispensing the second portion of the fluid coupling substance within the interior cavity.

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