Gyroscope and fabrication process

Patent metadata

Field	Value
Publication number	US-11548805-B2
Application number	US-201916726207-A
Country	US
Kind code	B2
Filing date	Dec 23, 2019
Priority date	Feb 29, 2016
Publication date	Jan 10, 2023
Grant date	Jan 10, 2023

Abstract

Gyroscopes are sensors that measure angular rate and angular orientation. A three-dimensional fused silica micro shell rate-integrating gyroscope is presented. One aspect of the gyroscope includes the use of optical sensors to detect motion of the resonator. The proposed gyroscope is attractive because it achieves several magnitudes higher accuracy as well as high vibration and shock insensitivity from a novel resonator design as well as other unique manufacturing processes.

First claim

What is claimed is:

1. A method for fabricating a mechanical resonator, comprising:
forming one or more grooves into a surface of a substantially planar reflow material;
disposing the planar reflow material on a mold, where the mold has a recess formed therein and the planar reflow material encloses the recess, wherein the mold further includes a protrusion projecting upward from a bottom surface of the recess;
heating the reflow material while the reflow material is disposed on the mold; and
reflowing the reflow material towards the bottom surface of the recess of the mold by creating a pressure gradient across the reflow material, thereby forming a resonator microstructure.

2. The method of claim 1 wherein the protrusion of the mold has a substantially hemispherical shape with a cylindrical hole formed in a center of the protrusion.

3. The method of claim 2 further comprises placing a post into the cylindrical hole of the protrusion, where reflow material flows into the cylindrical hole during the reflowing step and bonds with the post, thereby forming an integral stem.

4. The method of claim 1 further comprises controlling the pressure gradient across the reflow material independently from heating the reflow material.

5. The method of claim 1 further comprises heating the reflow material using a heat source and creating a pressure gradient across the reflow material using a vacuum that differs from the heat source.

6. The method of claim 1 further comprises
separating the resonator microstructure from the mold after the step of reflowing the reflow material;
polishing the resonator microstructure; and
coating an exterior surface of the resonator microstructure with a metal.

7. The method of claim 6 wherein coating an exterior of the resonator microstructure with a metal further comprises patterning the coating as a plurality of discrete electrodes disposed around a circumference of the resonator microstructure and proximate to the rim of the resonator microstructure.

8. The method of claim 1 further comprises: providing a support substrate; attaching the resonator microstructure to a top surface of the support substrate; forming a plurality of trenches in a bottom surface of the support substrate, such that each of the plurality of trenches is aligned underneath a rim of the resonator microstructure; embedding an optical sensor into each of the plurality of trenches such that each optical sensor is configured to detect motion of the mechanical resonator.

9. The method of claim 8 further comprises fabricating at least one driving electrode formed on the support substrate and arranged around a periphery of the resonator microstructure, where the at least one driving electrode is configured to drive the resonator microstructure electrostatically.

10. A method for fabricating a mechanical resonator, comprising:
forming an annulus on a surface of a substantially planar reflow material, where the annulus has a thickness larger than a remainder of the planar reflow material;
disposing the planar reflow material on a mold, where the mold has a recess formed therein and the planar reflow material encloses the recess, wherein the mold further includes a protrusion projecting upward from a bottom surface of the recess and positioned at center of the bottom surface of the recess;
heating the reflow material while the reflow material is disposed on the mold; and
reflowing the reflow material towards the bottom surface of the recess of the mold by creating a pressure gradient across the reflow material, thereby forming a resonator microstructure.

11. The method of claim 10 wherein the protrusion of the mold has a substantially hemispherical shape with a cylindrical hole formed in a center of the protrusion.

12. The method of claim 11 further comprises placing a post into the cylindrical hole of the protrusion, where reflow material flows into the cylindrical hole during the reflowing step and bonds with the post, thereby forming an integral stem.

13. The method of claim 12 further comprises controlling the pressure gradient across the reflow material independently from heating the reflow material.

14. The method of claim 13 further comprises heating the reflow material using a heat source and creating a pressure gradient across the reflow material using a vacuum that differs from the heat source.

15. The method of claim 14 further comprises
separating the resonator microstructure from the mold after the step of reflowing the reflow material;
polishing the resonator microstructure; and
coating an exterior surface of the resonator microstructure with a metal.

16. The method of claim 15 further comprises providing a support substrate; attaching the resonator microstructure to a top surface of the support substrate; forming a plurality of trenches in a bottom surface of the support substrate, such that each of the plurality of trenches is aligned underneath a rim of the resonator microstructure; embedding an optical sensor into each of the plurality of trenches such that each optical sensor is configured to detect motion of the mechanical resonator.

17. The method of claim 16 further comprises fabricating two or more driving electrodes formed on the support substrate and arranged around a periphery of the resonator microstructure, where the two or more driving electrodes are configured to drive the resonator microstructure electrostatically.

18. The method of claim 17 wherein coating an exterior of the resonator microstructure with a metal further comprises patterning the coating as a plurality of discrete electrodes disposed around a circumference of the resonator microstructure and proximate to the rim of the resonator microstructure, where each of the plurality of discrete electrodes aligns with one of the two or more driving electrodes.

19. A method for fabricating a mechanical resonator, comprising:
forming one or more grooves into a surface of a substantially planar reflow material;
disposing the planar reflow material on a mold, where the mold has a recess formed therein and the planar reflow material encloses the recess, wherein the mold further includes a protrusion projecting upward from a bottom surface of the recess, and wherein the protrusion has a circular cross section with respect to the bottom surface of the recess and includes a hole aligned with a center of the circular cross section of the protrusion;
heating the reflow material while the reflow material is disposed on the mold; and
reflowing the reflow material towards the bottom surface of the recess of the mold by creating a pressure gradient across the reflow material, thereby forming a resonator microstructure.

Assignees

• Univ Michigan Regents

Inventors

• Najafi Khalil
• Cho Jae Yoong
• DARVISHIAN Ali
• He Guohong
• Shiari Behrouz
• Nagourney Tal

Classifications

• C03B23/0252 Primary

  by gravity only, e.g. sagging (C03B23/035 takes precedence) · CPC title

• G01C25/00

  Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass (testing, calibrating or compensating compasses G01C17/38) · CPC title

• C03C15/00

  Surface treatment of glass, not in the form of fibres or filaments, by etching (etching or surface-brightening compositions, in general C09K13/00) · CPC title

• C03C17/06

  with metals (C03C17/34, C03C17/44 take precedence) · CPC title

• C03B23/0357

  by suction without blowing, e.g. with vacuum or by venturi effect · CPC title