Pressure sensors having improved drift compensation

Abstract

To provide a pressure sensor.SOLUTION: Disclosed example pressure sensors include: a temperature sensor; a pressure measurement assembly configured to output a pressure measurement signal; and measurement circuitry. Therein the measurement circuitry is configured to: in response to a first calibration trigger, record a first pressure measured via an electrode, a first timestamp, and a first temperature measurement measured via the temperature sensor; in response to a second calibration trigger, record a second pressure measured via the electrode, a second timestamp, and a second temperature measurement via the temperature sensor; and calculate a first sensor drift rate by determining a temperature-compensated second measured pressure by removing a first thermal shift from the second pressure and determining the first sensor drift rate as a first curve between the first measured pressure and the temperature-compensated second measured pressure.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] [Related Applications] This application claims the benefit of U.S. Patent Application No. 63 / 609,669, filed on December 13, 2023, entitled "PRESSURE SENSORS HAVING IMPROVED DRIFT COMPENSATION". The entire disclosure of U.S. Patent Application No. 63 / 609,669 is hereby incorporated by reference in its entirety.

[0002] This disclosure generally relates to pressure sensors, and more specifically to pressure transducers with improved drift compensation.

Background Art

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

Summary of the Invention

[0004] A pressure sensor with improved drift compensation is disclosed, substantially as shown by at least one of the drawings and described in connection therewith, as more fully set forth in the claims.

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

Brief Description of the Drawings

[0006]

Fig. 1A

[0007]

Fig. 1B

[0008]

Fig. 2

[0009]

Fig. 3

[0010]

Fig. 4

[0011] The drawings are not necessarily to scale. Like or identical reference numerals are used to refer to like or identical components when appropriate.

[0012] Reference is made herein to the embodiments shown in the drawings and described using specific terms, for the purpose of promoting an understanding of the principles of the claimed technology and presenting its currently understood best mode of operation. However, it will be understood that this is not intended to limit the scope of the claimed technology, and such changes and further modifications in the illustrated apparatus, and such further applications of the principles of the claimed technology as described herein, would typically occur to those skilled in the art related to the claimed technology.

[0013] Over time, conventional pressure sensors are exposed to contaminants, which can accumulate and cause a change in the measured capacitance for the same input pressure. This change in the measured capacitance over time (due to particulate accumulation and / or other causes) is known as "drift" in the pressure sensor. After sufficient time has passed, drift can cause a sufficient error in the output of the pressure sensor, which may require replacement of the pressure sensor. Since drift is unpredictable for each device, it is not possible to reliably predict drift during manufacturing.

[0014] The disclosed exemplary pressure sensors and methods compensate for drift occurring within a pressure sensor by measuring a drift rate over an interval and using the determined drift rate to predict drift for subsequent intervals. In some examples, the pressure sensor is calibrated at a fixed reference pressure, at which point the drift rate can be measured and predicted for subsequent intervals. The disclosed exemplary pressure sensors and methods eliminate temperature-based errors in determining the drift rate, such that errors due to temperature do not affect the determination of the current drift rate. The pressure sensor and method then use the drift rate to compensate the pressure measurement. As a result, the disclosed pressure sensors and methods reduce measurement errors over time.

[0015] As used herein, the term "fluid" includes substances in both liquid and gaseous states.

[0016] The disclosed exemplary pressure sensor includes a temperature sensor, a pressure measurement assembly configured to output a pressure measurement signal, and a measurement circuit unit. The measurement circuit unit records a first pressure measured via an electrode, a first timestamp, and a first temperature measurement value measured via the temperature sensor in response to a first calibration trigger, and records a second pressure measured via the electrode, a second timestamp, and a second temperature measurement value via the temperature sensor in response to a second calibration trigger. The measurement circuit unit is configured to calculate a first sensor drift rate by determining a temperature-compensated second measured pressure by removing a first thermal shift from the second pressure, and to calculate the first sensor drift rate as a first curve between the first measured pressure and the temperature-compensated second measured pressure.

[0017] In some exemplary pressure sensors, the temperature sensor is configured to measure the ambient temperature. In some exemplary pressure sensors, the measurement circuit unit is configured to compensate pressure measurement values after the second timestamp based on the calculated first sensor drift rate.

[0018] In some exemplary pressure sensors, the measurement circuit unit records a third pressure measured via an electrode, a third timestamp, and a third temperature measurement via a temperature sensor in response to a third calibration trigger, determines a temperature-compensated third measured pressure by removing a second thermal shift from the third pressure, and calculates the second sensor drift rate as a second curve between the temperature-compensated third measured pressure and at least one pressure prior to the third timestamp. In some exemplary pressure sensors, the measurement circuit unit is configured to compensate pressure measurement values after the third timestamp based on the calculated second sensor drift rate. In some exemplary pressure sensors, the measurement circuit unit is configured to determine a curve as a linear gradient from the temperature-compensated second measured pressure and the temperature-compensated third measured pressure, and is configured to compensate pressure measurement values after the third timestamp based on the second gradient. In some exemplary pressure sensors, the measurement circuit unit is further configured to calculate an additional sensor drift rate based on a corresponding calibration trigger and compensate subsequent pressure measurement values based on the most recent sensor drift rate.

[0019] In some exemplary pressure sensors, the first calibration trigger signal and the second calibration trigger signal are received via an operator input device. In some exemplary pressure sensors, the first calibration trigger signal and the second calibration trigger signal are generated by an external controller based on an external measurement sensor that determines that the input pressure is a predetermined reference pressure. In some exemplary pressure sensors, the first thermal shift is based on the difference between the first temperature measurement and the second temperature measurement. In some exemplary pressure sensors, the measurement circuit unit is configured to determine a temperature-compensated second measured pressure based on a stored thermal model for the pressure sensor.

[0020] In some exemplary pressure sensors, the measurement circuit section is configured to determine the drift rate as a linear gradient. In some exemplary pressure sensors, the measurement circuit section is configured to determine the drift rate as a polynomial curve. In some exemplary pressure sensors, the pressure measurement assembly includes at least one of a capacitive diaphragm gauge, a piezoresistive pressure sensor, a magnetic pressure sensor, a resonant frequency pressure sensor, an optical pressure sensor, or a piezoelectric voltage sensor.

[0021] The disclosed exemplary method for compensating a pressure sensor for drift includes recording, at a first time, a first pressure measured via a capacitive diaphragm gauge pressure sensor, a first timestamp, and a first temperature measurement measured via a temperature sensor; recording, at a second time, a second pressure measured via a capacitive diaphragm gauge pressure sensor, a second timestamp, and a second temperature measurement measured via a temperature sensor; calculating a first sensor drift rate by determining a temperature-compensated second measured pressure by removing a first thermal shift from the second pressure, and determining the first sensor drift rate as a curve between the first measured pressure and the temperature-compensated second measured pressure; and compensating pressure measurements after the second timestamp based on the calculated first sensor drift rate.

[0022] FIG. 1A is a block diagram of an exemplary process control system 100 including a pressure sensor 102. The exemplary process control system 100 of FIG. 1 includes a process chamber 104, and the pressure sensor 102 is fluidly coupled to the process chamber 104 via a fluid input line 106 to measure the pressure of the process chamber 104.

[0023] The exemplary process chamber 104 can receive one or more inputs, such as process feed materials, via a corresponding number of supply lines 108a, 108b that can be controlled via mass flow controllers 110a, 110b.

[0024] The exemplary system 100 can include a vacuum pump 112 or other pressure control 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 within the process chamber 104 within a desired range. The exemplary pressure sensor 102 is communicatively coupled to the controller 116 and supplies pressure feedback to the controller 116 (e.g., for use in a pressure control loop). For example, when the pressure within the process chamber 104 increases, the pressure sensor 102 measures the pressure and supplies 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.

[0025] In the example of FIG. 1A, the pressure sensor 102 is configured to have 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 will be described in more detail below, the pressure sensor 102 can be provided with a sealable exhaust port that can be sealed when a desired pressure is supplied within the pressure sensor 102, and / or the pressure sensor 102 can be assembled and sealed with a volume having a desired reference pressure. The fixed pressure 118 can be a vacuum pressure, or another predetermined fixed reference pressure that is lower than, equal to, or higher than atmospheric pressure. In the configuration of FIG. 1A, the pressure sensor 102 can be used as an absolute pressure sensor.

[0026] FIG. 1B is a block diagram of another exemplary process control system 150. The exemplary process control system 150 includes the exemplary pressure sensor 102, process chamber 104, fluid input line 106, supply lines 108a, 108b, mass flow controllers 110a, 110b, vacuum pump 112, valve 114, and controller 116 of FIG. 1A. In the example of FIG. 1B, the pressure sensor 102 is coupled to a variable source 152 of reference pressure that is external to the pressure sensor 102. For example, the pressure sensor 102 can be connected to a reference pressure source and operate as a pressure sensor with a variable reference, and / or have a port (e.g., a selectively sealable exhaust port) that is vented to ambient pressure and operates as a pressure gauge.

[0027] FIG. 2 is a schematic diagram of an exemplary pressure sensor 200 that can be used to implement the pressure sensor 102 of FIG. 1A and / or FIG. 1B. The exemplary pressure sensor 200 includes a pressure measurement assembly 202, an inner housing 204, and an outer housing 206. The pressure sensor 200 receives fluid via a fluid input line 208 (e.g., the fluid input line 106 of FIG. 1), measures the absolute pressure of the received fluid, and outputs one or more signals representative of the measured pressure.

[0028] The pressure measurement assembly 202 is a capacitive diaphragm gauge (CDG) sensor attached to the 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 surrounded by the inner housing 204. The inner housing 204 can provide thermal insulation and / or physical protection to the pressure measurement assembly 202. Both the pressure measurement assembly 202 and the inner housing 204 are at least partially surrounded by the outer housing 206. The outer housing 206 can provide thermal insulation and / or physical protection to the pressure measurement assembly 202.

[0029] In the illustrated example, the pressure measurement assembly 202 is a capacitive pressure sensor where a flexible diaphragm 210 is separated from an electrode 212 by a gap 214. The pressure measurement assembly 202 includes a first body 216 that defines a reference pressure cavity 218 and a second body 220 that defines a measurement pressure cavity 222. The second body 220 is coupled to the fluid input line 208 such that the measurement pressure cavity 222 has the same pressure as the fluid within the fluid input line 208. For example, the second body 220 can be sealed to the fluid input line 208 by welding, brazing, or other means to provide a hermetic seal.

[0030] When the pressure in the fluid input line 208 changes with respect to the reference pressure (e.g., vacuum pressure) within the reference pressure cavity 218, the diaphragm 210 moves or flexes, changing the capacitance at the measurement electrode 212 by an amount corresponding to the pressure within the fluid input line 208 and / or the measurement pressure cavity 222.

[0031] In the example of FIG. 2, the pressure measurement assembly 202 further includes a reference electrode 226 that similarly measures capacitance as the diaphragm 210 moves in response to pressure. The electrodes 212, 226 are metallized and form two capacitances with the flexible diaphragm 210. The signals generated by both electrodes 212, 226 change with pressure but at different rates. The signal from the reference electrode 226 is output via a signal port 228 and can be used to measure and offset common mode errors (e.g., temperature-induced errors).

[0032] The capacitance signal is output from the pressure measurement assembly 202 via a signal port 228 coupled to a measurement circuit section 238 that converts the capacitance into a measurement signal and / or outputs the capacitance signal to an external signal conversion device. The measurement circuit section 238 can correct the measurement signal(s). The measurement signal(s) representing the measured pressure within the pressure measurement assembly 202 may then be transmitted by the measurement circuit section 238 (e.g., to the controller 116 of FIG. 1A or FIG. 1B, another control and / or data collection device, etc.) via a communication circuit section 240 (e.g., a connector). In the example of FIG. 2, the exemplary measurement circuit section 238 and communication circuit section 240 are mounted within the pressure sensor 200 on one or more circuit boards.

[0033] To perform the measurement and processing, the measurement circuit section 238 can be implemented using at least one controller or processor that controls the operation of the pressure sensor 200. The measurement circuit section 238 receives and processes multiple inputs. The measurement circuit section 238 can include one or more microprocessors, such as one or more "general-purpose" microprocessors, one or more dedicated microprocessors and / or ASICs, and / or any other type of processing device. For example, the measurement circuit section 238 may include one or more digital signal processors (DSPs). The measurement circuit section 238 may further include a memory device and / or a data storage device.

[0034] The pressure sensor 200 can include a plasma shield 230 or other guard disposed between the fluid input line 208 and the diaphragm 210. The plasma shield 230 has one or more openings that allow the pressure of the input fluid to be applied to the diaphragm 210, but has one or more surfaces that block contaminants, thereby reducing the accumulation of contaminants on the diaphragm 210.

[0035] Exemplary materials that may be used to construct the first body 216 and / or the second body 220 include nickel alloys (e.g., Inconel™ alloys) and / or superalloys, cobalt superalloys, iron superalloys, aluminum, copper alloys, titanium, and / or corrosion-resistant alloys such as stainless steel.

[0036] To set a fixed reference pressure, the first body 216 can include an exhaust port 242 (e.g., a pinch tube or a pinch-off tube). The exhaust port 242 is in fluid communication with the reference pressure cavity 218. During manufacture and after sealing of the pressure measurement assembly 202, the pressure (e.g., a vacuum or other set pressure) within the reference pressure cavity 218 is drawn through the exhaust port 242 that is pinched to seal the reference pressure cavity 218 when the desired pressure level is reached. In some other examples, the pressure measurement assembly 202 may be constructed and sealed within a volume where the desired reference pressure exists, which fixes the desired reference pressure within the reference pressure cavity 218 when the exhaust port 242 is sealed within the fixed pressure chamber via welding or pinch-off cold welding.

[0037] In some examples where a fixed reference pressure is set, a getter may be installed within the reference pressure cavity 218 and activated during manufacture, such as when the fixed reference pressure has been established but before the reference pressure cavity 218 is sealed. Additionally or alternatively, the inner surface of the reference pressure cavity 218 (e.g., the first body 216, the electrode 212 adjacent to the reference pressure cavity 218) is coated with a substance that reduces or prevents gas evolution. An exemplary coating that may be used is parylene-C.

[0038] In some other examples, the exhaust port 242 may remain open to ambient pressure and / or may be connected to a variable source of reference pressure.

[0039] The inner housing 204 is attached to the second body 220 (e.g., using an adhesive, welding, press-fitting, etc.). The outer housing 206 is fixed to the measurement circuit unit 238 and / or the inner housing 204 (e.g., via a fastener, adhesive, welding, etc.).

[0040] The pressure sensor 200 further includes a temperature sensor 244 coupled to the measurement circuit unit 238. The temperature sensor 244 measures the ambient or other environmental temperature that can affect the measurement by the electrodes 212, 226. For example, a change in temperature can change the size of the gap 214 and / or the tension of the diaphragm 210.

[0041] As described above, the exemplary measurement circuit unit 238 can compensate for the drift that occurs over time in the pressure sensor 200. To compensate for the drift, the measurement circuit unit 238 can be calibrated at regular or irregular intervals to determine the measured output at a predetermined input pressure, as described in more detail below. The exemplary measurement circuit unit 238 can use sequential calibration to determine the drift rate and compensate the measured value based on the determined drift rate.

[0042] Since the temperature of the pressure sensor 200 can contribute to the measurement error in addition to the drift, the exemplary measurement circuit unit 238 compensates for the calibration of the pressure sensor 200 to reduce or eliminate the temperature-based error from the determination of the drift rate.

[0043] The measurement circuit unit 238 records the time stamp, the pressure output voltage, and the ambient temperature T at a predetermined fixed pressure P0 that can be any pressure. The measurement circuit unit 238 can record the data in response to a trigger input that can be an automatic trigger or an input device (e.g., a calibration button) accessible to the operator.

[0044] FIG. 3 is a graph 300 showing an example of a current drift rate calculation that can be performed by the pressure sensor 200 of FIG. 2. The graph 300 shows a set of calibration measurements 302, 304, 306 taken at different times (t1, t2, t3) at the same predetermined pressure. The predetermined pressure is separate from the pressure sensor 200 and can be determined based on a pressure sensor fluidly coupled to the input line 208.

[0045] At the first time t1 and the predetermined pressure P0, the measurement circuit unit 238 records the time stamp t1, the output V1 of the electrode 212, and the temperature T1 measured by the temperature sensor 244 as the calibration measurement 302. V1 and T1 are stored as base or reference measurements.

[0046] At the second time t2 and the predetermined pressure P0, the measurement circuit unit 238 records the time stamp t2, the output V2 of the electrode 212, and the temperature T2 measured by the temperature sensor 244 as the calibration measurement 304. Using the stored temperature coefficients at multiple temperatures (e.g., % of maximum sensitivity per degree Celsius) (e.g., TZS for the temperature coefficient at zero output, TSS for the temperature coefficient at maximum sensitivity), and the maximum sensitivity output (VFS), the measurement circuit unit 238 calculates the thermal shift VT2 between the first time t1 and the second time t2 using Equation 1. VT2 = TZS * VFS * (T2 - T1) + TSS * V1 * (T2 - T1) (Equation 1)

[0047] To compensate for subsequent measurements, the measurement circuit unit 238 determines the estimated drift rate (S12) from t1 to t2 using Equation 2. S12 = (V2’ - V1) / (t2 - t1) (Equation 2)

[0048] In Equation 2, V2’ is the temperature-compensated output, and is calculated as V2’ = V2 - VT2. The measurement circuit unit 238 compensates the pressure measurement value using the estimated drift rate S12 from after t2 until t3. In order to compensate the measured value of the pressure, the measurement circuit unit 238 removes, from the measured values after t2, an estimated drift amount that increases according to the estimated drift rate S12 as time elapses from t2. The measurement circuit unit 238 compensates the pressure measurement values that occur after t2 in order to determine the compensated output V’ using Equation 3. V’ = V - (V2’ - V1) - S12 * (t - t2) - VT (Equation 3)

[0049] In Equation 3, V is the measured pressure output from the electrode 212, t is the time of the measured pressure output, and the thermal shift VT is determined according to Equation 4. VT = TZS * VFS * (T - T1) + TSS * V * (T - T1) (Equation 4)

[0050] At the third time t3 and a predetermined pressure P0, the measurement circuit unit 238 records the time stamp t3, the output V3 of the electrode 212, and the temperature T3 measured by the temperature sensor 244 as the calibration measurement value 306. Using the stored temperature coefficients TZS, TSS, and the maximum sensitivity output VFS, the measurement circuit unit 238 calculates the thermal shift VT3 between the first time t1 and the third time t3 using Equation 5. VT3 = TZS * VFS * (T3 - T1) + TSS * V1 * (T3 - T1) (Equation 5)

[0051] The measurement circuit unit 238 again configures the output value of the pressure P0 to be equal to V1 to calibrate the output signal from the electrode 212. In order to compensate subsequent measurement values following the time t3, the measurement circuit unit 238 determines the estimated drift rate (S23) (which may be different from the drift rate from t1 to t2 and / or from t1 to t3) from t2 to t3 using Equation 6. S23 = (V3’ - V2’) / (t3 - t2) (Equation 6)

[0052] In Equation 6, V3’ is calculated as V3 - VT3. The measurement circuit unit 238 continues to compensate the pressure measurement value generated after t3, substitutes the current drift rate S23, the most recent compensated output, and the time t3, and determines the compensated output V’ using Equation 3 above.

[0053] The measurement circuit unit 238 can repeat calibration, drift rate calculation, and compensation for additional time past t3 in order to reduce the output error resulting from the drift of the pressure sensor 200 over the operating life of the pressure sensor 200.

[0054] Graph 300 shows the total drift 310 from t1 to t2, the estimated drift 312 from t2 to t3, the total compensated drift 314 at t3, and the remaining uncompensated drift 316 at t3.

[0055] Instead of a linear drift rate as shown in the example of FIG. 3, the exemplary measurement circuit unit 238 can calculate other drift curves such as a polynomial drift curve. The drift curve can be obtained based on fitting a predetermined drift curve trend to the observed temperature-compensated output and time stamps. For example, the measurement circuit unit 238 can perform regression analysis and / or any other type of analysis to determine the drift curve.

[0056] Additionally or alternatively, the measurement circuit unit 238 can store all calibration data (e.g., time stamps, output signals, measured temperatures, etc.) in a storage device for later retrieval. For example, the calibration data may be stored permanently, or at least for a predetermined or configurable time period, and / or up to the memory limit of the measurement circuit unit 238. The stored calibration data can be output to a maintenance system (e.g., via the communication circuit unit 240). The maintenance system can analyze the calibration data of the pressure sensor 200 and update the approximation curve coefficients (e.g., for performing curve fitting) based on, for example, the observed data and / or for a specific application or use of the pressure sensor 200. The maintenance system then loads and returns the updated coefficients to the measurement circuit unit 238 for storage and updated drift compensation determination. The coefficients determined based on the first pressure sensor 200 may be further loaded into a replacement pressure sensor 200, such that the new pressure sensor 200 can have more accurate curve fitting coefficients for the same or similar applications.

[0057] Figure 4 is a flowchart representing exemplary machine-readable instructions 400 that may be executed by the pressure sensor 200 of FIG. 2 to compensate for pressure measurements for sensor drift. The exemplary instructions 400 are described below with reference to the measurement circuit unit 238. In the following instructions 400, baseline measurements of pressure V1, time t1, and temperature T1 may be pre-captured upon startup or initialization of the pressure sensor 200.

[0058] In block 402, the measurement circuit unit 238 determines whether to calibrate the pressure sensor 200. For example, the measurement circuit unit 238 can receive an input signal from a control device (e.g., via the communication circuit unit 240) or via a user input device (e.g., a calibration button). If calibration is to be performed (block 402), the measurement circuit unit 238 inputs a predetermined pressure into the fluid input line 208. For example, a known input pressure source may be connected to the input line 208, or the connected system may be configured to input a predetermined input pressure.

[0059] In block 406, the measurement circuit unit 238 captures the pressure measurement value, the time stamp, and the temperature measurement value. For example, the measurement circuit unit 238 can receive a signal from the electrode 212, a time stamp from a timer or a clock, and a temperature measurement value of the ambient temperature or the environmental temperature from the temperature sensor 244 to represent one of the calibration measurement values 302, 304, 306 in FIG. 3. In block 408, the measurement circuit unit 238 determines the temperature-compensated current pressure measurement value. For example, the measurement circuit unit 238 can determine the temperature-compensated current pressure measurement value V2' based on the thermal shift calculated using Equation 1 above.

[0060] In block 410, the measurement circuit unit 238 determines the current sensor drift rate (e.g., S12, S23, etc.) as a curve based on the previously measured pressure (e.g., baseline or temperature-compensated) and the temperature-compensated current pressure measurement value. For example, the measurement circuit unit 238 may determine the linear drift rate using Equation 2 or Equation 6, or may determine a polynomial drift curve or other non-linear drift curve.

[0061] After determining the sensor drift rate (block 410), or if the pressure sensor is not calibrated (block 402), in block 412, the measurement circuit unit 238 determines whether a pressure measurement value has been captured. For example, the measurement circuit unit 238 can determine the pressure measurement signal V from the electrode 212 at regular or irregular intervals and / or in response to a trigger or an event. If the pressure measurement value is not captured (block 412), the control returns to block 412.

[0062] If the pressure measurement value is not captured (block 412), in block 414, the measurement circuit unit 238 captures the temperature measurement value via the temperature sensor 244.

[0063] In block 416, the measurement circuit section 238 compensates the pressure measurement signal V using the current sensor drift rate, the time stamp of the pressure measurement value, and the temperature measurement value. For example, the measurement circuit section 238 can use Equation 3 to determine the corrected pressure output. Then, the control returns to block 402.

[0064] The examples disclosed above are described with reference to CDG sensors, but the disclosed exemplary systems and methods are applicable to other types of pressure sensors that are subject to drift, such as piezoresistive pressure sensors, magnetic pressure sensors, resonant frequency pressure sensors, optical pressure sensors, piezoelectric pressure sensors, and / or any other type of pressure sensor.

[0065] 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" serves 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.

[0066] Although the method and / or system have been described with reference to certain embodiments, those skilled in the art will understand that various changes can be made and equivalents can be substituted without departing from the scope of the method and / or system. For example, the blocks and / or components of the disclosed examples can be combined, divided, rearranged, and / or otherwise changed. Additionally, many modifications can be made to adapt the teachings of the present disclosure to specific situations or materials without departing from the scope of the present disclosure. Accordingly, the method and / or system are not limited to the specific embodiments disclosed. Instead, the method and / or system include all embodiments that fall within the scope of the appended claims, literally or under the doctrine of equivalents.

Claims

1. A temperature sensor; a pressure measurement assembly configured to output a pressure measurement signal; A measurement circuit unit, in response to a first calibration trigger, recording a first pressure measured via the electrodes, a first timestamp, and a first temperature measurement measured via the temperature sensor; in response to a second calibration trigger, recording a second pressure measured via the electrodes, a second timestamp, and a second temperature measurement via the temperature sensor; The first sensor drift rate is determining a temperature compensated second measured pressure by removing the first thermal shift from the second pressure; measurement circuitry configured to calculate the first sensor drift rate by determining a first curve between the first measured pressure and the temperature compensated second measured pressure; A pressure sensor comprising:

2. The pressure sensor of claim 1 , wherein the temperature sensor is configured to measure an ambient temperature.

3. The pressure sensor of claim 1 , wherein the measurement circuitry is configured to compensate pressure measurements after the second time stamp based on the calculated first sensor drift rate.

4. The measurement circuit unit includes: in response to a third calibration trigger, recording a third pressure measured via the electrodes, a third timestamp, and a third temperature measurement via the temperature sensor; The second sensor drift rate is determining a temperature compensated third measured pressure by removing the second thermal shift from the third pressure; 2. The pressure sensor of claim 1, further configured to calculate the second sensor drift rate by determining a second curve between the temperature compensated third measured pressure and at least one pressure prior to the third timestamp.

5. The pressure sensor of claim 4 , wherein the measurement circuitry is configured to compensate pressure measurements after the third time stamp based on the calculated second sensor drift rate.

6. 6. The pressure sensor of claim 5, wherein the measurement circuitry is configured to determine the curve as a linear slope from the temperature compensated second measured pressure and the temperature compensated third measured pressure, and to compensate the pressure measurement after the third time stamp based on the second slope.

7. The pressure sensor of claim 4 , wherein the measurement circuitry is further configured to calculate an additional sensor drift rate based on a corresponding calibration trigger and to compensate subsequent pressure measurements based on a most recent sensor drift rate.

8. The pressure sensor of claim 1 , wherein the first calibration trigger signal and the second calibration trigger signal are received via an operator input device.

9. The pressure sensor of claim 1 , wherein the first calibration trigger signal and the second calibration trigger signal are generated by an external controller based on an external measurement sensor determining that the input pressure is a predetermined reference pressure.

10. The pressure sensor of claim 1 , wherein the first thermal shift is based on a difference between the first temperature measurement and the second temperature measurement.

11. The pressure sensor of claim 10 , wherein the measurement circuitry is configured to determine the temperature compensated second measured pressure based on a stored thermal model for the pressure sensor.

12. The pressure sensor of claim 1 , wherein the measurement circuitry is configured to determine the drift rate as a linear slope.

13. The pressure sensor of claim 1 , wherein the measurement circuitry is configured to determine the drift rate as a polynomial curve.

14. The pressure sensor of claim 1 , wherein the pressure measurement assembly includes at least one of a capacitive diaphragm gauge (CDG), a piezoresistive pressure sensor, a magnetic pressure sensor, a resonant frequency pressure sensor, an optical pressure sensor, or a piezoelectric pressure sensor.

15. 1. A method of compensating a pressure sensor for drift, comprising: recording at a first time a first pressure measured via a capacitive diaphragm gauge pressure sensor, a first time stamp, and a first temperature measurement measured via a temperature sensor; recording at a second time a second pressure measured via the capacitive diaphragm gauge pressure sensor, a second timestamp, and a second temperature measurement measured via the temperature sensor; The first sensor drift rate is determining a temperature compensated second measured pressure by removing the first thermal shift from the second pressure; calculating the first sensor drift rate by determining a curve between the first pressure measurement and the temperature compensated second pressure measurement; compensating pressure measurements after the second time stamp based on the calculated first sensor drift rate; A method comprising:

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