Piezoelectric resonator, a piezoelectric material for a piezoelectric resonator, and a method for manufacturing a piezoelectric resonator
The present disclosure relates to piezoelectric resonator, a piezoelectric material for a piezoelectric resonator, and a method for manufacturing a piezoelectric resonator. In particular, it relates to piezoelectric resonator comprising a piezoelectric material, where the piezoelectric material is configured to have an improved shear wave velocity.
1 . A piezoelectric resonator comprising:
a piezoelectric material, wherein the piezoelectric material is configured to have a reduced hydrogen content for increasing the shear wave velocity of the piezoelectric material, wherein the hydrogen content of the piezoelectric material is reduced to a level of approximately 0.05 wt·ppm or less;
wherein a resonant frequency of the piezoelectric resonator, comprising the piezoelectric material having the reduced hydrogen content, is increased by a factor of at least 1.2 relative to a resonant frequency of a piezoelectric resonator comprising the piezoelectric material not having a reduced hydrogen content, wherein said piezoelectric material not having a reduced hydrogen content has a hydrogen content of 1.98 wt·ppm.
2 . The piezoelectric resonator according to claim 1 , wherein the resonant frequency of the piezoelectric resonator, comprising the piezoelectric material having the reduced hydrogen content, when measured in water, is at least 6 MHz.
3 . The piezoelectric resonator according to claim 2 , wherein the resonant frequency of the piezoelectric resonator, comprising the piezoelectric material having the reduced hydrogen content, when measured in water, is at least 14 MHz.
4 . The piezoelectric resonator according to claim 1 , wherein the resonant frequency of the piezoelectric resonator, comprising the piezoelectric material having the reduced hydrogen content, when measured in water, is one of at least 7 MHz, 7.2 MHz, 8.4 MHz, 9.6 MHz, 9.8 MHz, 10.8 MHz, 11.2 MHz and 12.6 MHz.
5 . The piezoelectric resonator according to claim 1 , wherein the resonant frequency of the piezoelectric resonator, comprising the piezoelectric material having the reduced hydrogen content, is improved by a factor of at least 1.4.
6 . The piezoelectric resonator according to claim 1 , wherein a Q factor of the piezoelectric resonator, comprising the piezoelectric material having the reduced hydrogen content, is improved relative to a Q factor of a piezoelectric resonator comprising the piezoelectric material not having a reduced hydrogen content.
7 . The piezoelectric resonator according to claim 6 , wherein the Q factor of the piezoelectric resonator, comprising the piezoelectric material having the reduced hydrogen content, is improved by a factor of at least 1.1.
8 . The piezoelectric resonator according to claim 6 , wherein the Q factor of the piezoelectric resonator, comprising the piezoelectric material having the reduced hydrogen content, when measured in water, is at least 1450.
9 . The piezoelectric resonator according to claim 1 , wherein the piezoelectric material comprises a crystal plate.
10 . The piezoelectric resonator according to claim 1 , wherein the piezoelectric material has a thickness from 160 μm to 350 μm.
11 . The piezoelectric resonator according to claim 10 , wherein the piezoelectric material is a quartz crystal plate.
12 . The piezoelectric resonator according to claim 1 , wherein the piezoelectric resonator comprises a first electrode and a second electrode, wherein each electrode has a predetermined area and wherein the first electrode covers a first planar surface of the piezoelectric material and the second electrode covers a second planar surface of the piezoelectric material, the second planar surface being opposite to the first planar surface of the piezoelectric material.
13 . The piezoelectric resonator according to claim 12 , wherein each electrode partially covers the respective planar surface of the piezoelectric material.
14 . The piezoelectric resonator according to claim 12 , wherein the first electrode includes a first portion extending onto the second surface of the piezoelectric material.
15 . The piezoelectric resonator according to claim 1 , wherein the piezoelectric resonator is encapsulated.
16 . The piezoelectric resonator according to claim 15 , wherein the piezoelectric resonator is encapsulated in a casing, which may include one or more of: a polymer; a metal casing, a silicon cap, or a hydrophobic material.
17 . A mass-sensitive chemical sensor comprising the piezoelectric resonator according to claim 1 .
18 . A piezoelectric sensor element for chemical analysis of a fluid sample, the sensor element comprising:
the mass-sensitive chemical sensor according to claim 17 ;
a sample chamber being configured to receive a fluid sample and further configured to facilitate contact of a fluid sample with the mass-sensitive chemical sensor; and
one or more flow channels in fluid connection with the sample chamber for directing the flow of the fluid sample to and from the sample chamber.
19 . The piezoelectric sensor element according to claim 18 , wherein the sample chamber is further configured to hold the mass-sensitive chemical sensor.
20 . A piezoelectric sensor system for chemical analysis of a fluid sample, the piezoelectric sensor system comprising:
the piezoelectric sensor element according to claim 18 ;
a sample insertion unit for introducing the fluid sample to the sensor element;
a signal source for providing electric signals to the piezoelectric sensor element for generation of an oscillating motion of the piezoelectric resonator in the piezoelectric sensor element; and
a processing unit for measuring the resonant frequency of the piezoelectric resonator and for generating an output signal representing the said resonant frequency.
21 . The piezoelectric sensor system according to claim 20 , wherein the sample insertion unit is a removable unit.
22 . An oscillator circuit for generating a clock signal, the oscillator circuit comprising a piezoelectric resonator according to claim 1 .
23 . A method for increasing the shear wave velocity of a piezoelectric material, the method comprising:
providing the piezoelectric material, the piezoelectric material having a predetermined thickness; and
removing hydrogen from the piezoelectric material;
wherein the hydrogen content of the piezoelectric material is reduced to a level of approximately 0.05 wt·ppm or less;
wherein a resonant frequency of the piezoelectric resonator, comprising the piezoelectric material having the reduced hydrogen content, is increased by a factor of at least 1.2 relative to a resonant frequency of a piezoelectric resonator comprising the piezoelectric material not having a reduced hydrogen content, wherein said piezoelectric material not having a reduced hydrogen content has a hydrogen content of 1.98 wt·ppm.
24 . A piezoelectric material for a piezoelectric resonator, wherein the piezoelectric material has a reduced hydrogen content for increasing the shear wave velocity of the piezoelectric material, wherein the piezoelectric material is configured to have a hydrogen content reduced to a level of approximately 0.05 wt·ppm or less, wherein a resonant frequency of the piezoelectric resonator, comprising the piezoelectric material having the reduced hydrogen content, is increased by a factor of at least 1.2 relative to a resonant frequency of a piezoelectric resonator comprising the piezoelectric material not having a reduced hydrogen content, wherein said piezoelectric material not having a reduced hydrogen content has a hydrogen content of 1.98 wt·ppm.