Coil actuated pressure sensor and deformable substrate

Patent metadata

Field	Value
Publication number	US-10955306-B2
Application number	US-201916390355-A
Country	US
Kind code	B2
Filing date	Apr 22, 2019
Priority date	Apr 22, 2019
Publication date	Mar 23, 2021
Grant date	Mar 23, 2021

Abstract

A pressure sensor comprises a deformable substrate, at least one coil supported by the substrate and responsive to a changing coil drive signal to produce a changing magnetic field, a fluid chamber having a first wall formed by the substrate and a second wall formed by a conductive material and positioned proximate to the at least one coil so that the changing magnetic field produces eddy currents within the conductive material that generate a reflected magnetic field, and at least one magnetic field sensing element configured to detect the reflected magnetic field and produce a signal responsive to a distance between the magnetic field sensing element and the second wall. The substrate is deformable by fluid pressure within the fluid chamber and the deformation of the substrate changes the distance between the magnetic field sensing element and the second wall.

First claim

The invention claimed is:

1. A pressure sensor comprising:
a substrate;
at least one coil supported by the substrate and responsive to a changing coil drive signal to produce a changing magnetic field;
a fluid chamber having a first wall formed by the substrate and a second wall formed by a conductive material and positioned proximate to the at least one coil so that the changing magnetic field produces eddy currents within the conductive material that generate a reflected magnetic field; and
at least one magnetic field sensing element configured to detect the reflected magnetic field and produce a signal responsive to a distance between the magnetic field sensing element and the second wall;
wherein the substrate is deformable by fluid pressure within the fluid chamber and the deformation of the substrate changes the distance between the magnetic field sensing element and the second wall.

2. The pressure sensor of claim 1 wherein the substrate is a semiconductor substrate.

3. The pressure sensor of claim 2 wherein the substrate comprises a through-silicon via.

4. The pressure sensor of claim 3 wherein the substrate is in a flip-chip position with the at least one magnetic field sensing element positioned between the at least one coil and the second wall.

5. The pressure sensor of claim 2 wherein the substrate is in a die-up position with the at least one coil positioned between the at least one magnetic field sensing element and the second wall.

6. The pressure sensor of claim 1 further comprising an adhesive to adhere the substrate to the second wall.

7. The pressure sensor of claim 6 wherein the adhesive comprises one or more of an anodic bond, a metal to glass seal, or an adhesive bond.

8. The pressure sensor of claim 7 wherein the adhesive is between the substrate and the second wall.

9. The pressure sensor of claim 8 wherein a thickness of the adhesive forms a gap between the substrate and the second wall.

10. The pressure sensor of claim 7 wherein the adhesive covers an edge of the substrate.

11. The pressure sensor of claim 1 wherein the fluid chamber comprises a third wall formed by a conductive material and positioned proximate to a second coil that produces a second changing magnetic field, wherein the second changing magnetic field produces second eddy currents within the conductive material of the third wall that generate a second reflected magnetic field.

12. The pressure sensor of claim 11 further comprising a second magnetic field sensing element configured to detect the second reflected magnetic field and produce a signal responsive to a distance between the second magnetic field sensing element and the third wall.

13. The pressure sensor of claim 1 further comprising at least one bond wire coupled to a via in the substrate.

14. The pressure sensor of claim 1 wherein the second wall comprises a notch and the substrate is positioned in the notch.

15. The pressure sensor of claim 1 further comprising a strain gauge supported by the substrate and configured to generate an output signal representing a strain on the substrate caused by the deformation of the substrate.

16. A system comprising:
a processor;
a pressure sensor electrically coupled to the processor and configured to generate a signal in response to a fluid pressure, the pressure sensor comprising:
a substrate;
at least one coil supported by the substrate and responsive to a changing coil drive signal to produce a changing magnetic field;
a fluid chamber having a first wall formed by the substrate and a second wall formed by a conductive material and positioned proximate to the at least one coil so that the changing magnetic field produces eddy currents within the conductive material that generate a reflected magnetic field; and
at least one magnetic field sensing element configured to detect the reflected magnetic field and produce a signal responsive to a distance between the magnetic field sensing element and the second wall;
wherein the substrate is deformable by fluid pressure within the fluid chamber and the deformation of the substrate changes the distance between the magnetic field sensing element and the second wall.

17. The system of claim 16 wherein the substrate comprises a through-silicon via.

18. The system of claim 17 wherein the substrate is in a flip-chip position with the at least one magnetic field sensing element positioned between the at least one coil and the second wall.

19. The system of claim 16 wherein the substrate is in a die-up position with the at least one coil positioned between the at least one magnetic field sensing element and the second wall.

20. The system of claim 16 further comprising an adhesive to adhere the substrate to the second wall.

21. The system of claim 20 wherein the adhesive comprises one or more of an anodic bond, a metal to glass seal, or an adhesive bond.

22. The system of claim 20 wherein the adhesive is between the substrate and the second wall.

23. The system of claim 20 wherein the adhesive covers an edge of the substrate.

24. The system of claim 16 wherein the fluid chamber comprises a third wall formed by a conductive material and positioned proximate to a second coil that produces a second changing magnetic field, wherein the second changing magnetic field produces second eddy currents within the conductive material of the third wall that generate a second reflected magnetic field.

25. The system of claim 24 further comprising a second magnetic field sensing element configured to detect the second reflected magnetic field and produce a signal responsive to a distance between the second magnetic field sensing element and the third wall.

26. The system of claim 16 further comprising at least one bond wire coupled to the substrate.

27. A pressure sensor comprising:
a substrate that forms a first wall of a chamber;
a conductive target that forms a second wall of the chamber;
means for generating a reflected magnetic field from the conductive target;
means for generating a magnetic field signal in response to the reflected magnetic field;
means for detecting a distance between the substrate and the second wall of the chamber based on the magnetic field signal; and
means for changing the distance between the substrate and the conductive target in response to a change in pressure within the chamber.

Assignees

• Allegro Microsystems Llc

Inventors

• Cadugan Bryan
• Boudreau Jason
• Taylor William P

Classifications

• G01R33/09

  Magnetoresistive devices · CPC title

• G01L17/00

  Devices or apparatus for measuring tyre pressure or the pressure in other inflated bodies · CPC title

• G01L9/0004

  using variations in inductance (G01L9/007 takes precedence) · CPC title

• G01B7/023

  for measuring distance between sensor and object (G01B7/082 and G01B7/102 take precedence) · CPC title

• G01L9/007

  using variations in inductance · CPC title