Micromachined bulk acoustic wave resonator pressure sensor
First Claim
1. A pressure sensor, comprising:
- a piezoelectric substrate having a generally planar structure and a neutral axis, an upper electrode on the planar structure and a lower electrode on the planar structure to drive the resonance of the piezoelectric substrate and sense the frequency of the piezoelectric substrate;
an anchor location fixing the piezoelectric substrate to a fixture at the periphery of the planar structure of the piezoelectric substrate;
wherein the planar structure of the piezoelectric substrate has a first region having a first characteristic thickness adjacent to the anchor location, and a second region have a second characteristic thickness at a middle region of the substrate,wherein the second characteristic thickness is less than the first characteristic thickness such that the planar structure in the second region is configured to be displaced relative to the neutral axis of the planar structure when pressure is directly applied to the piezoelectric substrate perpendicular to the neutral axis such that, while undergoing bending, the second region has either mostly compressive or mostly tensile stress, andwherein the pressure range of the pressure applied to the piezoelectric substrate is between one atmosphere and 10−
6 Torr.
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Abstract
A pressure sensor includes a piezoelectric substrate having a generally planar structure and an anchor location fixing the piezoelectric substrate at the periphery of the planar structure of the piezoelectric substrate. The planar structure of the piezoelectric substrate has a first region having a first characteristic thickness adjacent to the anchor location, and a second region have a second characteristic thickness at a middle region of the substrate. The second characteristic thickness is less than the first characteristic thickness such that the planar structure in the second region is displaced relative to the neutral axis of the planar structure such that while undergoing bending the second region has either mostly compressive or mostly tensile stress.
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Citations
22 Claims
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1. A pressure sensor, comprising:
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a piezoelectric substrate having a generally planar structure and a neutral axis, an upper electrode on the planar structure and a lower electrode on the planar structure to drive the resonance of the piezoelectric substrate and sense the frequency of the piezoelectric substrate; an anchor location fixing the piezoelectric substrate to a fixture at the periphery of the planar structure of the piezoelectric substrate; wherein the planar structure of the piezoelectric substrate has a first region having a first characteristic thickness adjacent to the anchor location, and a second region have a second characteristic thickness at a middle region of the substrate, wherein the second characteristic thickness is less than the first characteristic thickness such that the planar structure in the second region is configured to be displaced relative to the neutral axis of the planar structure when pressure is directly applied to the piezoelectric substrate perpendicular to the neutral axis such that, while undergoing bending, the second region has either mostly compressive or mostly tensile stress, and wherein the pressure range of the pressure applied to the piezoelectric substrate is between one atmosphere and 10−
6 Torr. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A bulk acoustic wave resonator pressure sensor including a diaphragm, the diaphragm comprising:
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a substrate having a generally planar structure and a neutral axis, the planar structure including a first surface and a second surface opposite the first surface, a portion of the first surface being etched to a pre-selected depth; a first electrode deposited and patterned on the first surface; a second electrode deposited and patterned on the second surface; wherein the first and second electrodes are configured to measure changes in an at-resonance impedance characteristic of the pressure sensor when pressure is directly applied to one of the first surface or the second surface perpendicular to the neutral axis, and wherein the pressure range applied to the substrate is between one atmosphere and 10−
6 Torr. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification