Strain compensation for pressure sensors

Patent metadata

Field	Value
Publication number	US-9958351-B2
Application number	US-201213428108-A
Country	US
Kind code	B2
Filing date	Mar 23, 2012
Priority date	Mar 24, 2011
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

A pressure sensing system provides signals representative of a magnitude of pressure at a selected site. A sensor module includes a first transducer producing a first signal having an associated first response to pressure and strain applied to the sensor module and a second transducer producing a second signal having an associated second response to pressure and strain applied to the sensor module. A calculated pressure, a bending pressure error and a bend-compensated pressure are computed in response to the first signal and the second signal.

First claim

The invention claimed is:

1. A pressure sensing system for providing signals representative of a magnitude of pressure at a selected site, comprising:
a sensor module at least one of on or enclosed within a sensor housing module configured for implantation within a patient, the sensor module comprising:
a first transducer configured to produce a first signal having an associated first response to pressure and a bending moment applied to the sensor module; and
a second transducer configured to produce a second signal having an associated second response to pressure and the bending moment applied to the sensor module, wherein the second response is different than the first response,
wherein the first transducer and the second transducer are coupled to a substrate, the first transducer located in a peripheral region of the substrate relative to the second transducer; and

a processor configured to:
receive the first signal and the second signal, and
determine a calculated pressure based on the first signal, wherein the calculated pressure includes a bending pressure error due to bending of the sensor module,
determine the bending pressure error based on the first signal and the second signal, and
determine a bend-compensated pressure in response to receiving the first signal and the second signal based on the bending pressure error.

2. The system of claim 1 wherein the first transducer is a capacitive transducer.

3. The system of claim 1 wherein the second transducer comprises a microelectromechanical system (MEMS) device.

4. The system of claim 1 , wherein the second transducer comprises:
a first component, wherein the first component is configured to produce a first output having a first response to bending and temperature applied to the module; and
a second component, wherein the second component is configured to produce a second output having a second response to bending and temperature applied to the module, wherein the second response is different than the first response,
wherein the processor is configured to receive the second signal from at least one of the first output and the second output, and wherein the processor is configured to determine the bending pressure error based on the first signal and the second signal.

5. The system of claim 4 , wherein the processor is configured to determine the calculated pressure based on the first signal and one of the first output and the second output, and wherein the processor is configured to determine the bending pressure error based on the calculated pressure and the second signal.

6. The system of claim 5 , wherein the processor is configured to determine the calculated pressure by at least determining a ratio based on the first signal and one of the first output and the second output, and wherein the processor is configured to determine the bending pressure error based on a ratio between the first output and the second output.

7. The system of claim 4 , further comprising:
a memory associated with the processor, wherein the memory is configured to store a reference measurement determined using the second signal measured at a zero bending moment of the sensor module and a coefficient determined during a calibration procedure when a bending moment corresponding to a known moment fraction is applied to the sensor module, and
wherein the processor is configured to determine the bending pressure error based on a difference between the stored reference measurement and a measurement of the second signal at an unknown bending moment applied to the sensor module and the coefficient applied to the difference.

8. The system of claim 1 , wherein the processor is configured to determine the bending pressure error by at least determining a moment fraction using the first signal and the second signal, wherein the moment fraction is an estimate of a relative change in the bending moment applied to the sensor module.

9. The system of claim 1 , wherein the sensor module further comprises:
a hybrid circuit mounted on the substrate, wherein the hybrid circuit comprises:
a first component having a first output associated with a first temperature response; and
a second component having a second output associated with a second temperature response different than the first temperature response,

wherein the processor is further configured to determine a temperature signal based on the first output and the second output, and wherein the processor is configured to determine the bending pressure error based on the temperature signal.

10. The system of claim 9 , further comprising:
a memory associated with the processor, wherein the memory configured to store a measurement of the temperature signal determined at zero bending of the sensor module, and
wherein the processor is configured to determine the bending pressure error based on a difference between the stored temperature signal measurement and a temperature signal measurement at an unknown bending moment of the sensor module.

11. The system of claim 1 , further comprising:
a memory associated with the processor, wherein the memory is configured to store a calculated pressure determined at a zero bending moment of the sensor module and a coefficient determined during a calibration procedure when a bending moment corresponding to a known moment fraction is applied to the sensor module, and
wherein the processor is configured to determine the bending pressure error based on a difference between a calculated pressure determined at an unknown bending moment of the sensor module and the stored calculated pressure determined at the zero bending moment and the coefficient applied to the difference.

12. The system of claim 1 , wherein the processor is configured to determine the bend compensated pressure based on a difference between the calculated pressure and the bending pressure error.

13. The system of claim 1 , further comprising:
a memory associated with the processor, wherein the memory is configured to store a look-up table of bending pressure error values for a range of the calculated pressure and a range of reference measurements stored for a range of known bending moments applied to the sensor module,
wherein the processor is further configured to determine a reference measurement from the second signal when an unknown bending moment is applied to the sensor module, and wherein the processor is configured to determine the bending pressure error from the look-up table using the calculated pressure and the reference measurement.

14. The system of claim 1 , wherein the processor is configured to control a therapy delivered by a therapy delivery unit based at least in part on the bend-compensated pressure determined in response to detecting the first signal and the second signal based on the bending pressure error.

15. A pressure sensing system for providing signals representative of a magnitude of pressure at a selected site, comprising:
a sensor module comprising:
a first transducer configured to produce a first signal having an associated first response to pressure and a bending moment applied to the sensor module; and
a second transducer configured to produce a second signal having an associated second response to pressure and the bending moment applied to the sensor module, wherein the second response is different than the first response,
wherein the second transducer comprises:
a first component, wherein the first component is configured to produce a first output having a first response to bending and temperature applied to the module; and
a second component, wherein the second component is config

Assignees

• Kuhn Jonathan L
• Obrien Richard J
• Roberts Jonathan P
• Reinke James D
• Terry Michael B
• Mothilal Kamal Deep
• Medtronic Inc

Inventors

• Kuhn Jonathan L
• O'Brien Richard J
• Roberts Jonathan P
• Reinke James D
• Terry Michael B
• Mothilal Kamal Deep

Classifications

• G01L15/00

  Devices or apparatus for measuring two or more fluid pressure values simultaneously · CPC title

• A61B5/205

  Determining bladder or urethral pressure · CPC title

• G01L9/125 Primary

  with temperature compensating means (non electric temperature compensating means G01L19/04) · CPC title

• G01L19/149

  of immersion sensor, e.g. where the sensor is immersed in the measuring medium or for in vivo measurements, e.g. by using catheter tips · CPC title

• A61B5/42

  Detecting, measuring or recording for evaluating the gastrointestinal, the endocrine or the exocrine systems (A61B1/00, A61B5/4857, A61B5/486, A61B5/4866, A61B5/4869 take precedence) · CPC title