Pressure transducer with improved tolerance to temperature errors

Abstract

An exemplary pressure sensor disclosed includes a first body defining a reference pressure cavity, a second body defining a measurement pressure cavity and having an inlet configured to receive a fluid, a diaphragm between the reference pressure cavity and the measurement pressure cavity, a single electrode comprising a plate portion having a first surface facing the diaphragm and separated from the diaphragm by a gap, forming a capacitance between the electrode and the diaphragm, an electrode extension secured to the electrode and extending through a hole in the first body, and an electrically insulating joint disposed at least partially within the hole between the electrode extension and the first body, wherein the first body, electrode, and electrode extension have respective geometries and thermal expansion coefficients selected such that the combined expansion of the electrode and electrode extension in response to temperature changes offsets changes in the gap caused by the expansion of the first body.

Description

[Technical Field]

[0001] [Related Applications] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 424,712, filed November 11, 2022, entitled "PRESSURE TRANSDUCERS HAVING IMPROVED RESISTANCE TO TEMPERATURE ERROR," the entirety of which is expressly incorporated herein by reference.

[0002] The present disclosure relates generally to pressure transducers, and more particularly to pressure transducers with improved tolerance to temperature errors. [Background technology]

[0003] A pressure sensor or pressure transducer measures the pressure of a fluid input to the sensor which is compared to a reference pressure. Pressure sensors can be constructed to compare the input pressure to a fixed or variable reference pressure. Summary of the Invention

[0004] A pressure transducer with improved tolerance to temperature errors is disclosed, substantially as shown by and described in connection with at least one of the drawings, as more fully set forth in the claims.

[0005] These and other features, aspects, and advantages of the present disclosure will be better understood when the following detailed description is read in conjunction with the accompanying drawings, in which like reference characters represent like parts throughout. [Brief explanation of the drawings]

[0006] [Figure 1A] FIG. 1 is a block diagram of an example process control system with a pressure transducer having a fixed reference pressure, in accordance with aspects of the present disclosure.

[0007] [Figure 1B] FIG. 1 is a block diagram of an example process control system including a pressure transducer coupled to a variable reference pressure source, according to aspects of the present disclosure.

[0008] [Figure 2] FIG. 1C is a schematic diagram of an exemplary pressure sensor that can be used to implement the pressure sensor of FIGS. 1A and / or 1B, according to an embodiment of the present disclosure.

[0009] [Figure 3] FIG. 3 is an exploded perspective view of the exemplary pressure measurement assembly of FIG. 2.

[0010] [Figure 4] 3 is another exploded perspective view of the exemplary pressure measurement assembly of FIG. 2.

[0011] [Figure 5] 3 is a flowchart illustrating an example method that may be performed to assemble the example pressure sensor of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0012] The drawings are not necessarily to scale. Where appropriate, like or identical reference numbers are used to refer to like or identical components.

[0013] For the purposes of promoting an understanding of the principles of the claimed technology and setting out its best currently understood mode of operation, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same, it being understood, however, that no limitation on the scope of the claimed technology is intended, and it is contemplated that such changes and further modifications in the illustrated apparatus, and such further applications of the principles of the claimed technology as described therein, would typically occur to one skilled in the art to which the claimed technology pertains.

[0014] Conventional pressure sensors convert input pressure into a pressure signal. Some conventional sensors detect the pressure difference between the input pressure and a reference pressure based on the capacitance between a flexible diaphragm and a fixed electrode. However, conventional capacitance-based pressure sensors are sensitive to temperature differences, and temperature changes can cause changes in friction between contacting parts and / or the capacitance that exists between the diaphragm and the electrode. For example, thermal expansion of components in conventional pressure sensors can cause changes in the gap between the diaphragm and the electrode, resulting in errors in pressure measurements. To reduce thermally induced errors, some conventional capacitance-based pressure sensors include multiple electrodes, including a reference electrode, to compensate for temperature changes.

[0015] The disclosed example pressure transducers improve pressure sensing by reducing sensitivity to temperature changes while using a single electrode (e.g., omitting a reference electrode). In some examples, a pressure measurement assembly includes a first body that, together with a diaphragm, defines a reference pressure cavity and within which an electrode resides. The geometry and / or materials of the first body, electrode, and / or electrode extension are selected to compensate for thermal expansion, thereby reducing or eliminating thermally induced errors.

[0016] The disclosed pressure transducers may be cheaper and / or simpler to construct, more reliable, and / or easier to service and / or maintain than conventional capacitive pressure sensors. In some examples, getters typically used in vacuum pressure gauges can be eliminated by coating the reference pressure cavity with a non-outgassing coating, such as Parylene C.

[0017] The disclosed exemplary pressure transducers have improved performance compared to conventional capacitive pressure sensors due to the omission of the reference electrode and the resulting signal subtraction, resulting in improved thermal performance and / or signal strength compared to multi-electrode pressure sensors.

[0018] As used herein, the term "fluid" includes substances in both liquid and gaseous states.

[0019] An exemplary pressure sensor disclosed includes a first body defining a reference pressure cavity, a second body defining a measurement pressure cavity and having an inlet configured to receive a fluid, a diaphragm between the reference pressure cavity and the measurement pressure cavity, a single electrode having a plate portion with a first surface facing the diaphragm and separated from the diaphragm by a gap, forming a capacitance between the electrode and the diaphragm, an electrode extension fixed to the electrode and passing through a hole in the first body, and an electrically insulating joint disposed at least partially within the hole between the electrode extension and the first body, wherein the first body, electrode, and electrode extension have respective geometric shapes and thermal expansion coefficients selected such that the combined expansion of the electrode and electrode extension in response to temperature changes (e.g., temperature increases) offsets changes in the gap caused by the expansion of the first body.

[0020] In some exemplary pressure sensors, the electrically insulating joint provides a hermetic seal between the electrode extension and the first body. In some examples, the seal comprises glass. In some exemplary pressure sensors, the first body has a higher coefficient of thermal expansion than both the seal and the electrode extension. In some exemplary pressure sensors, the seal forms a compression seal between the first body and the electrode extension.

[0021] In some exemplary pressure sensors, the first body includes an exhaust port. In some exemplary pressure sensors, the exhaust port is selectively sealable to fix a pressure in the reference pressure cavity. In some exemplary pressure sensors, the first body further includes a getter in the reference pressure cavity, and the fixed pressure is a vacuum pressure. In some exemplary pressure sensors, the inner surface of the first body is coated to reduce outgassing.

[0022] In some exemplary pressure sensors, the exhaust port is configured to be coupled to a reference pressure source to configure the pressure sensor as a differential pressure sensor. In some exemplary pressure sensors, the exhaust port is configured to be vented to ambient pressure to configure the pressure sensor as a gauge pressure sensor. In some exemplary pressure sensors, the first body includes a corrosion-resistant alloy.

[0023] In some example pressure sensors, the electrode extension comprises Kovar™ alloy or Alloy 52. ​​In some example pressure sensors, the electrode comprises a metal, such as stainless steel, that has a higher coefficient of thermal expansion than the material of the first body. Some example pressure sensors further include measurement circuitry coupled to the electrode extension and configured to convert a capacitance between the electrode and the diaphragm into a pressure value.

[0024] In some example pressure sensors, the diaphragm is secured between the first body and the second body along the periphery of the diaphragm. In some example pressure sensors, the first body and the second body are welded together along the periphery of the first body and the second body with the diaphragm secured between the first body and the second body.

[0025] 1A is a block diagram of an example process control system 100 including a pressure transducer 102. The example process control system 100 of FIG. 1 includes a process chamber 104 to which the pressure transducer 102 is fluidly coupled via a fluid input line 106 to measure the pressure in the process chamber 104.

[0026] The example process chamber 104 can accept one or more inputs, such as process feed materials, via a corresponding number of supply lines 108a, 108b, which can be controlled via mass flow controllers 110a, 110b.

[0027] The example system 100 can include a vacuum pump 112 or other pressure-controlled pump and a valve 114 that controls the flow rate between the vacuum pump 112 and the process chamber 104. The valve 114 can be controlled by a controller 116, a computing device, and / or any other control technique to maintain the pressure in the process chamber 104 within a desired range. The example pressure transducer 102 is communicatively coupled to the controller 116 and provides pressure feedback to the controller 116 (e.g., for use in a pressure control loop). For example, as the pressure in the process chamber 104 increases, the pressure transducer 102 measures the pressure and provides a signal representative of the pressure to the controller 116, which then controls the valve 114 to increase the flow rate from the process chamber 104 to the vacuum pump 112. The vacuum pump 112 can have an output to any suitable location based on the nature of the process.

[0028] In the example of FIG. 1A, the pressure transducer 102 is configured with a fixed pressure 118, and the input pressure of the fluid received via the fluid input line 106 is compared to the fixed pressure 118 to output a pressure signal. For example, as described in more detail below, the pressure transducer 102 can be provided with a sealable exhaust port that can be sealed when a desired pressure is applied within the pressure transducer 102, and / or the pressure transducer 102 can be assembled and sealed in a volume having a desired reference pressure. The fixed pressure 118 can be a vacuum pressure or another predetermined fixed reference pressure that can be less than, equal to, or greater than nominal atmospheric pressure. In the configuration of FIG. 1A, the pressure transducer 102 can be used as an absolute pressure sensor.

[0029] 1B is a block diagram of another example process control system 150. The example process control system 150 includes the example pressure transducer 102 of FIG. 1A, the process chamber 104, the fluid input line 106, the supply lines 108a, 108b, the mass flow controllers 110a, 110b, the vacuum pump 112, the valve 114, and the controller 116. In the example of FIG. 1B, the pressure transducer 102 is coupled to a variable reference pressure source 152 that is external to the pressure transducer 102. For example, the pressure transducer 102 can have a port (e.g., a selectively sealable exhaust port) that is connected to a reference pressure source to operate as a pressure sensor with a variable reference and / or that is vented to ambient pressure to operate as a pressure gauge.

[0030] Figure 2 is a schematic diagram of an example pressure transducer 200 that can be used to implement the pressure transducers 102, 150 of Figures 1A and / or 1B. The example pressure transducer 200 includes a pressure measurement assembly 202, an inner housing 204, and an outer housing 206. The pressure transducer 200 receives fluid via a fluid input line 208 (e.g., fluid input line 106 of Figure 1), measures the absolute pressure of the received fluid, and outputs one or more signals indicative of the measured pressure.

[0031] The pressure measurement assembly 202 is attached to a fluid input line 208. The pressure measurement assembly 202 may also be referred to as a "sensor core" in that the pressure measurement assembly 202 performs measurements that are converted into output signals. The pressure measurement assembly 202 is at least partially enclosed by an inner housing 204. The inner housing 204 may provide thermal insulation and / or physical protection for the pressure measurement assembly 202. Both the pressure measurement assembly 202 and the inner housing 204 are at least partially enclosed by an outer housing 206.

[0032] In the illustrated example, pressure measurement assembly 202 is a capacitive pressure sensor in which a flexible diaphragm 210 is separated from an electrode 212 by a gap 214. Pressure measurement assembly 202 includes a first body 216 defining a reference pressure cavity 218 and a second body 220 defining a measurement pressure cavity 222. Second body 220 is coupled to fluid input line 208 such that measurement pressure cavity 222 has the same pressure as the fluid in fluid input line 208. For example, second body 220 can be welded, brazed, or otherwise sealed to fluid input line 208 to provide an airtight seal.

[0033] The illustrated electrode 212 has a surface 224 facing the diaphragm 210, with the surface 224 separated from the diaphragm by a substantially constant gap. The diaphragm 210 and the electrode 212 form a capacitance that varies with changes in the distance between the diaphragm 210 and the electrode 212, and this capacitance can be measured to determine the relative pressure between the reference pressure cavity 218 and the measurement pressure cavity 222.

[0034] To measure capacitance, the electrode 212 is coupled to an electrode extension 226 that extends from the electrode 212 through a hole 228 in the first body 216 to the exterior of the first body 216. The electrode extension 226 may be integral with or attached to the electrode 212. The electrode 212 and the electrode extension 226 may be collectively referred to herein as an electrode assembly.

[0035] The example pressure measurement assembly 202 further includes a joint 230 positioned at least partially within the bore 228 between the electrode extension 226 and the first body 216. The joint 230 provides electrical insulation between the electrode extension 226 and the first body 216.

[0036] The diaphragm 210 is positioned between a first body 216 and a second body 220, which are welded or otherwise mechanically and hermetically attached to one another. The dimensions of the first body 216, the electrode 212, and the electrode extension 226 establish a gap 214 between the electrode 212 and the diaphragm 210.

[0037] In some examples, the joint 230 also provides a hermetic seal. For example, the joint 230 can be implemented using a glass insert, such as S8061 type glass. To form a hermetic seal, the materials of the first body 216, the joint 230, and the electrode extension 226 can be selected so that the thermal expansion coefficient of the first body 216 is greater than the thermal expansion coefficients of both the joint 230 and the electrode extension 226. The seal provided by the joint 230 can be established by heating the first body 216, the joint 230, and the electrode extension 226 to melt the joint 230. During subsequent cooling, the joint 230 solidifies while the first body 216 and the electrode extension 226 shrink. When the first body 216, the joint 230, and the electrode extension 226 cool, the first body 216 compresses the joint 230 and the electrode extension 226 due to the first body's higher coefficient of thermal expansion.

[0038] The example first body 216, electrode 212, and electrode extension 226 also have geometries and materials configured such that the combined expansion of the electrode 212 and electrode extension 226 offsets changes in gap 214 caused by the expansion of the first body 216. For example, as the temperature of the pressure measurement assembly 202 increases, the first body 216 expands such that the electrode extension 226 and electrode 212 are pulled away from the diaphragm. Meanwhile, the electrode 212 and electrode extension 226 expand with increasing temperature, moving the face 224 of the electrode 212 toward the diaphragm. The example first body 216, electrode 212, and electrode extension 226 of the example pressure measurement assembly 202 have geometries and materials (e.g., thermal expansion coefficients) that offset changes in gap 214 caused by the expansion of the first body 216 by offsetting the expansion of the electrode extension 226 and electrode 212.

[0039] As an example, the first body 216 can be constructed to have a particular dimension 232 that corresponds to the height of the reference pressure cavity 218. Additionally, the first body 216 can have a first linear thermal expansion coefficient (also referred to herein as the coefficient of thermal expansion) CLTE ボディ The electrode 212 is constructed from a material having a second coefficient of thermal expansion CLTE. The electrode 212 is constructed with a height dimension 234, and the electrode extension 226 has a partial height dimension 236 between its interface with the electrode 212 and the interior edge of the hole 228 (e.g., where the joint 230 limits the movement of the electrode extension 226). The electrode 212 is constructed from a material having a second coefficient of thermal expansion CLTE. 電極 and the electrode extension 226 is constructed of a material having a third coefficient of thermal expansion CLTE 延長部 The material is constructed from a material having a coefficient of thermal expansion (CTE). Equation 1 below shows the relationship between dimensions 232-236 and the coefficient of thermal expansion.

[0040] Body height 232 x CLTE ボディ = (electrode height 234 × CLTE 電極 ) + (Partial extension height 236 × CLTE 延長部 )(Formula 1)

[0041] Since the body height dimension 232 is greater than the sum of the electrode height dimension 234 and the partial extension height dimension 236, the coefficient of thermal expansion CLTE 電極 and / or CLTE 延長部 At least one of the coefficients of thermal expansion is greater than the coefficient of thermal expansion of the first body 216 .

[0042] Exemplary materials from which the first body 216 and / or the second body 220 may be constructed include corrosion-resistant alloys such as nickel alloys (e.g., Inconel™ alloys) and / or superalloys, cobalt superalloys, iron superalloys, aluminum, copper alloys, titanium, and / or stainless steel.

[0043] Exemplary materials that can be used to construct electrode extension 226 include low thermal expansion alloys such as Kovar™ alloy or Alloy 52. ​​As used herein, "low thermal expansion" refers to a material with a thermal expansion of up to 6×10 -6 This refers to the coefficient of thermal expansion in °F / °C.

[0044] Exemplary materials that can be used to construct electrode 212 include stainless steel and / or other metals that have a higher coefficient of expansion than the material used to construct first body 216 .

[0045] As the pressure in the fluid input line 208 changes relative to the reference pressure in the reference pressure cavity 218, the diaphragm 210 deflects, causing a change in capacitance in response to the pressure in the fluid input line 208. A capacitance signal is output from the pressure measurement assembly 202 via the electrode extension 226 and coupled to the measurement circuitry 238, which converts the capacitance to a measurement signal and / or outputs the capacitance signal to an external signal conversion device. The measurement circuitry 238 may compensate the measurement signal(s). The measurement signal(s) indicative of the measured pressure in the pressure measurement assembly 202 may then be transmitted by the measurement circuitry 238 via a communication port 240 (e.g., a connector) (e.g., to the controller 116 of FIG. 1A or FIG. 1B, another control device and / or data collection device, etc.).

[0046] 2, example measurement circuitry 238 and communication ports 240 are mounted on one or more circuit boards 250 within pressure transducer 200. The example circuit boards 250 in FIG. 2 are positioned in a parallel orientation relative to diaphragm 210. In other examples, one or more of circuit boards 250 are mounted in other orientations, such as perpendicular to diaphragm 210, to improve packaging and / or resilience of pressure measurement assembly 202.

[0047] To set a fixed reference pressure, first body 216 can include an exhaust port 242 (e.g., a pinch tube or pinch-off tube). Exhaust port 242 is in fluid communication with reference pressure cavity 218. During manufacture and after pressure measurement assembly 202 is sealed, pressure (e.g., a vacuum or other set pressure) within reference pressure cavity 218 is drawn through exhaust port 242, pinching off exhaust port 242 to seal reference pressure cavity 218 once a desired pressure level is reached. In other examples, pressure measurement assembly 202 can be constructed and sealed within a volume where the desired reference pressure exists, thereby fixing the desired reference pressure within reference pressure cavity 218 when exhaust port 242 is sealed within the fixed pressure chamber via welding or cold pinch-off welding.

[0048] In some examples where a fixed reference pressure is set, a getter can be placed in reference pressure cavity 218 and activated during manufacturing, e.g., before the fixed reference pressure is established and reference pressure cavity 218 is sealed. Additionally or alternatively, the interior surfaces of reference cavity 218 (e.g., first body 216, electrode 212, and / or electrode extension 226 adjacent reference pressure cavity 218) are coated with a material that reduces or prevents outgassing. One example of a coating that may be used is Parylene C.

[0049] In some other examples, the exhaust port 242 may be left open to ambient pressure and / or connected to a variable reference pressure source.

[0050] The example pressure measurement assembly 202 further includes a plasma shield 244 that protects the diaphragm 210 from the accumulation of process by-products and particles from the fluid input line 208 .

[0051] Inner housing 204 is attached (e.g., using glue, welding, a press fit, etc.) to second body 220. Outer housing 206 is secured (e.g., via fasteners, adhesive, welding, etc.) to measurement circuitry 238 and / or inner housing 204.

[0052] 2, the second body 220 further includes a protected volume 246 that is recessed from the plasma shield 244 and the diaphragm 210. The protected volume 246 accumulates particle deposits that may be introduced into the measurement pressure cavity 222 via the fluid input line 208. By accumulating particles in the protected volume 246, particle deposits on the diaphragm are reduced, extending the life of the diaphragm 210.

[0053] In some examples, exhaust port 242 is large enough to facilitate the use of a masking fixture to apply a coating (e.g., Parylene C) after inner housing 204 is attached to second body 220. In such examples, exhaust port 242 can be sealed using plug 248. After the coating is applied, plug 248 can be inserted into exhaust port 242 while a base pressure is established and electron beam welded or otherwise secured within exhaust port 242 to seal the base pressure within base pressure cavity 218.

[0054] Figure 3 is an exploded perspective view of the example pressure measurement assembly 202 of Figure 2. Figure 4 is another exploded perspective view of the example pressure measurement assembly 202 of Figure 2.

[0055] Figure 5 is a flow chart illustrating an example method 500 that may be performed to assemble the example pressure transducer 200 of Figure 2. Although one example manufacturing method is described with reference to Figure 5, other methods may be used, such as methods that include additive manufacturing and / or other techniques that reduce the number of bonding operations performed.

[0056] At block 502, the first body 216, the electrode assembly (eg, the electrode 212 and electrode extension 226), and the seal preform (eg, the joint 230) are assembled.

[0057] In block 504, the seal preform (e.g., joint 230) is melted, and in block 506, the seal preform is cooled to form a solid, gas-tight seal between first body 216 and the electrode assembly. In some examples, blocks 504 and 506 can be omitted if a gas-tight seal is not used.

[0058] At block 508, the plasma shield 244 and the second body 220 are assembled together. At block 510, the diaphragm 210, the first body 216, and the second body 220 are assembled and secured together (eg, using welding).

[0059] If the reference pressure in the reference pressure cavity 218 is to be a fixed reference pressure (block 512), then in block 514, the desired reference pressure is brought into the reference pressure cavity 218 in the first body 216. For example, the reference pressure may be drawn through the exhaust port 242. In block 516, the exhaust port 242 is sealed to fix the reference pressure.

[0060] After fixing the reference pressure (block 516), or if a fixed reference pressure is not used), the inner housing 204 is installed in block 518. For example, the pressure measuring assembly 202 can be inserted into the inner housing 204, with the electrode extension 226 passing through the inner housing 204.

[0061] At block 520, the electrode assembly is connected to the measurement circuitry 238 (eg, via the electrode extension 226).

[0062] At block 522, the pressure transducer 200 is calibrated for various pressures and / or temperatures.

[0063] At block 524, the outer housing 206 is installed. For example, the inner housing 204 and / or the outer housing 206 may be welded, glued, or otherwise attached to the pressure measurement assembly 202 and / or the fluid input line 208.

[0064] As used herein, "and / or" means any one or more of the items in the list connected by "and / or." As an example, "x and / or y" means any element of the three-element set {(x), (y), (x, y)}. In other words, "x and / or y" means "one or both of x and y." As another example, "x, y and / or z" means any element of the seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}. In other words, "x, y and / or z" means "one or more of x, y and z." As used herein, the term "exemplary" means serving as a non-limiting example, instance, or illustration. As used herein, the term "for example" begins a list of one or more non-limiting examples, instances, or illustrations.

[0065] Although the present method and / or system has been described with reference to certain specific embodiments, those skilled in the art will recognize that various modifications and equivalent substitutions may be made without departing from the scope of the present method and / or system. For example, blocks and / or components of the disclosed examples may be combined, divided, rearranged, and / or otherwise modified. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the scope of the present disclosure. Therefore, the present method and / or system is not limited to the particular embodiments disclosed. Instead, the present method and / or system includes all embodiments falling within the scope of the appended claims, both literally and under the doctrine of equivalents.

Claims

1. A pressure sensor, a first body defining a reference pressure cavity; a second body defining a measurement pressure cavity, the second body having an inlet configured to receive a fluid; a diaphragm between the reference pressure cavity and the measurement pressure cavity; a single electrode including a plate portion having a first surface facing the diaphragm and separated from the diaphragm by a gap to form a capacitance between the electrode and the diaphragm; an electrode extension fixed to the electrode and extending through a hole in the first body; an electrically insulating joint disposed at least partially within the bore between the electrode extension and the first body; Equipped with the first body, the electrode, and the electrode extension have respective geometries and thermal expansion coefficients selected such that, in response to temperature changes, the combined expansion of the electrode and the electrode extension offsets changes in the gap caused by expansion of the first body. Pressure sensor.

2. The pressure sensor of claim 1 , wherein the electrically insulating joint provides an airtight seal between the electrode extension and the first body.

3. The pressure sensor of claim 2 , wherein the seal comprises glass.

4. The pressure sensor of claim 2 , wherein the first body has a higher coefficient of thermal expansion than both the seal and the electrode extension.

5. The pressure sensor of claim 2 , wherein the seal forms a compression seal between the first body and the electrode extension.

6. The pressure sensor of claim 1 , wherein the first body includes an exhaust port.

7. The pressure sensor of claim 6 , wherein the exhaust port is selectively sealable to fix a pressure within the reference pressure cavity.

8. 8. The pressure sensor of claim 7, further comprising a getter in the reference pressure cavity, wherein the fixed pressure is a vacuum pressure.

9. The pressure sensor of claim 7 , wherein an inner surface of the first body is coated to reduce outgassing.

10. The pressure sensor of claim 6 , wherein the exhaust port is configured to be coupled to a source of reference pressure to configure the pressure sensor as a differential pressure sensor.

11. The pressure sensor of claim 6 , wherein the exhaust port is configured to be vented to ambient pressure to configure the pressure sensor as a gauge type.

12. The pressure sensor of claim 1 , wherein the first body comprises a corrosion-resistant alloy.

13. The pressure sensor of claim 1 , wherein the electrode extension comprises Kovar alloy or 52 alloy.

14. The pressure sensor of claim 1 , wherein the electrode comprises stainless steel having a higher coefficient of thermal expansion than a material of the first body.

15. 10. The pressure sensor of claim 1, further comprising measurement circuitry coupled to the electrode extension and configured to convert the capacitance between the electrode and the diaphragm into a pressure value.

16. The pressure sensor of claim 1 , wherein the diaphragm is secured between the first body and the second body along a periphery of the diaphragm.

17. 2. The pressure sensor of claim 1, wherein the first body and the second body are welded together along their peripheries with the diaphragm secured between the first body and the second body.

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