Structures, acoustic wave resonators, devices and systems to sense a target variable, including as a non-limiting example corona viruses

1. A sensor system comprising:

a substrate;

a Bulk Acoustic Wave (BAW) resonator arranged over the substrate, the BAW resonator including: a first piezoelectric layer, a second piezoelectric layer and a top electrode; and

a sensing region comprising a functionalized layer, the sensing region comprising the functionalized layer being acoustically coupled with the second piezoelectric layer via the top electrode of the BAW resonator, in which the top electrode is electrically and acoustically coupled with the second piezoelectric layer to excite a main resonant frequency of the BAW resonator coupled with the sensing region, and in which acoustic coupling of the second piezoelectric layer with the sensing region for the main resonant frequency of the BAW resonator coupled with the sensing region is approximately four gigahertz or higher in a super high frequency band or an extremely high frequency band to facilitate an enhanced sensitivity of the sensing region comprising the functionalized layer.

2. The sensor system as in claim 1 in which the main resonant frequency of the BAW resonator coupled with the sensing region is approximately four thirty nine gigahertz or higher.

3. The sensor system as in claim 1 in which the main resonant frequency of the BAW resonator coupled with the sensing region is approximately eight gigahertz or higher.

4. The sensor system as in claim 1 in which the main resonant frequency of the BAW resonator coupled with the sensing region is approximately twenty four gigahertz or higher.

5. The sensor system as in claim 1 in which the main resonant frequency of the BAW resonator coupled with the sensing region is in an Institute of Electrical and Electronic Engineers (IEEE) K band.

6. The sensor system as in claim 1 in which the main resonant frequency of the BAW resonator coupled with the sensing region is in an Institute of Electrical and Electronic Engineers (IEEE) Ka band.

7. The sensor system as in claim 1 in which:

the first piezoelectric layer has a first piezoelectric axis;

the second piezoelectric layer of has a second piezoelectric axis; and

the BAW resonator comprises:

a third piezoelectric layer interposed between the first piezoelectric layer and the second piezoelectric layer, the third piezoelectric layer having a third piezoelectric axis substantially opposing the first piezoelectric axis and the second piezoelectric axis;

a fourth piezoelectric layer; and

a fifth piezoelectric layer.

8. The sensor system as in claim 1 in which a total quality factor of the BAW resonator including sheet resistance of the top electrode is within a range from approximately three hundred to approximately fifteen hundred.

9. The sensor system as in claim 1 in which the BAW resonator comprises a bottom electrode, a second pair of piezoelectric layers, and a third pair of piezoelectric layers,

and in which the first piezoelectric layer, the second piezoelectric layer, the second pair of piezoelectric layers, and the third pair of piezoelectric layers, are interposed between the top electrode and the bottom electrode to facilitate an enhancement in a quality factor associated with the sensor system.

10. The sensor system as in claim 1 in which the sensing region is configured to sense an analyte present in a liquid.

11. The sensor system as in claim 1 in which the sensing region is configured to sense an analyte present in an air sample.

12. A Micro Electro Mechanical System (MEMS) comprising:

a substrate;

a sensing region comprising a functionalized layer;

a Bulk Acoustic Wave (BAW) resonator arranged over the substrate, the BAW resonator including: a first layer of piezoelectric material having a first piezoelectric axis orientation; and a second layer of piezoelectric material having a second piezoelectric axis orientation that is antiparallel the first piezoelectric axis orientation of the first layer of piezoelectric material; and

a harmonic electrode acoustically coupled with the second layer of piezoelectric material and the sensing region to facilitate coupling acoustic energy from the second piezoelectric layer into the sensing region, and to facilitate suppressing parasitic lateral resonances.

13. The MEMS as in claim 12 in which the harmonic electrode has a thickness to facilitate an enhanced quality factor of the BAW resonator.

14. The MEMS as in claim 12 in which in which the first and second layers of piezoelectric material have respective thicknesses so that a main resonant frequency of the BAW resonator is in a super high frequency band or an extremely high frequency band.

15. The MEMS as in claim 12 in which the BAW resonator comprises a third layer of piezoelectric material to facilitate spurious mode suppression, in which the first, second and third layers of piezoelectric material have respective first, second and third piezoelectric axis orientations that substantially oppose one another in an alternating arrangement.

16. An apparatus comprising:

a sensing region comprising a functionalized layer;

a substrate;

a Bulk Acoustic Wave (BAW) resonator arranged over the substrate, the BAW resonator including a first layer of piezoelectric material; and

a harmonically tuned electrode having a thickness that is approximately an integral multiple of a half of an acoustic wavelength of a main resonant frequency of the BAW resonator coupled with the sensing region to facilitate acoustic coupling from the first layer of piezoelectric material into the sensing region.

17. An apparatus as in claim 16 in which the thickness of the harmonically tuned electrode is approximately one half of the acoustic wavelength of the main resonant frequency of the BAW resonator coupled with the sensing region.

18. The apparatus as in claim 16 in which in which the harmonically tuned electrode is to facilitate suppressing parasitic lateral resonances.

19. The apparatus as in claim 16 comprising a second layer of piezoelectric material having a second piezoelectric axis orientation, in which the first layer of piezoelectric material has a first piezoelectric axis orientation that substantially opposes the second piezoelectric axis orientation, and in which the thickness of the harmonically tuned electrode being approximately the integral multiple of the half of the acoustic wavelength is to facilitate acoustic coupling from the second layer of piezoelectric material into the sensing region.

20. The apparatus as in claim 16 in which

the main resonant frequency of the BAW resonator coupled with the sensing region is in an Institute of Electrical and Electronic Engineers (IEEE) L band.

21. The apparatus as in claim 16 in which

the main resonant frequency of the BAW resonator coupled with the sensing region is in an Institute of Electrical and Electronic Engineers (IEEE) S band.

22. A fluidic system comprising:

a substrate;

a Bulk Acoustic Wave (BAW) resonator arranged over the substrate, the BAW resonator including: first and second layers of piezoelectric material; and a top electrode; and

a sensing region acoustically coupled with the top electrode and the second layer of piezoelectric material, in which the sensing region comprises a functionalized layer to facilitate binding to an analyte, in which the fluidic system has sufficient sensitivity to detect down to approximately one hundred attograms of the analyte in a fluid for the sensing region acoustically coupled with the second layer of piezoelectric material, and in which:

the first layer of piezoelectric material has a first piezoelectric axis orientation; and

the second layer of piezoelectric material has a second piezoelectric axis orientation substantially opposing the first piezoelectric axis orientation of the first layer of piezoelectric material.

23. The fluidic system as in claim 22 in which the functionalized layer has a virus affinity.

24. The fluidic system as in claim 22 in which the fluidic system has sufficient sensitivity to detect down to a single virus particle in the fluid, for the fluid comprising water.

25. The fluidic system as in claim 22 in which the functionalized layer has a SARS-CoV-2 virus affinity.

26. The fluidic system as in claim 22 in which the sensing region acoustically coupled with the second layer of piezoelectric material and the top electrode of the BAW resonator has a sensing area within a range from approximately sixteen hundred square microns to approximately twenty five thousand six hundred square microns.

27. The fluidic system as in claim 22 comprising a plurality of Bulk Acoustic Wave (BAW) resonators having respective sensing regions in which the plurality of BAW resonators have respective differing piezoelectric layer thicknesses, to have respective main resonant frequencies that are different from one another, so as to facilitate identification of respective members of the plurality of Bulk Acoustic Wave resonators.

28. The fluidic system as in claim 22 comprising a plurality of Bulk Acoustic Wave (BAW) resonators having respective sensing regions in which the respective sensing regions comprise respective functionalized layers that are different from one another to facilitate binding to respective analytes that are different from one another.

29. The fluidic system as in claim 22 in which the BAW resonator comprises a third layer of piezoelectric material acoustically coupled with the sensing region via the top electrode, in which the first, second and third layers of piezoelectric material have respective first, second and third piezoelectric axis orientations that substantially oppose one another in an alternating arrangement.

30. The fluidic system as in claim 22 in which the top electrode approximates a harmonic electrode.