SELF-EXCITING, SELF-SENSING PIEZOELECTRIC CANTILEVER SENSOR

Abstract

A piezoelectric cantilever sensor includes a piezoelectric layer and a non-piezoelectric layer, a portion of which is attached to the piezoelectric layer. In one embodiment, one end of the non-piezoelectric layer extends beyond the end of piezoelectric layer to provide an overhang. The overhang piezoelectric cantilever sensor enables increased sensitivity allowing application of the device in more viscous environments, such as liquid media, as well as application in liquid media at higher flow rates than conventional piezoelectric cantilevers. In another embodiment, the sensor includes first and second bases and at least one of the piezoelectric layer and the non-piezoelectric layer is affixed to each of the first and second bases to form the piezoelectric cantilever sensor. In this embodiment, the sensor is robust and exhibits excellent sensing characteristics in both gaseous and liquid media, even when subjected to relatively high flow rates.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating a self-exciting, self-sensing piezoelectric cantilever sensor, there is shown in the drawings exemplary constructions thereof, however, a self-exciting, self-sensing piezoelectric cantilever sensor is not limited to the specific methods and instrumentalities disclosed.

FIG. 1 is an illustration of an example configuration of a self-exciting, self-sensing piezoelectric cantilever sensor.

FIG. 2 is a cross-sectional view of an example self-exciting, self-sensing piezoelectric cantilever sensor depicting electrode placement regions for electrodes operationally associated with the piezoelectric layer.

FIG. 3 is a cross-sectional view of an example self-exciting, self-sensing piezoelectric cantilever sensor showing depicting example electrode placement within a base portion of the self-exciting, self-sensing piezoelectric cantilever sensor.

FIG. 4 is a cross-sectional view of an example self-exciting, self-sensing piezoelectric cantilever sensor showing depicting example electrode placement not within a base portion of the self-exciting, self-sensing piezoelectric cantilever sensor.

FIG. 5 is an illustration of an example configuration of a self-exciting, self-sensing piezoelectric cantilever sensor wherein the distal end of the piezoelectric layer is flush with the distal end of the non-piezoelectric layer.

FIG. 6 is an illustration of an example configuration of a self-exciting, self-sensing piezoelectric cantilever sensor wherein the distal end of the piezoelectric layer extends beyond the distal end of the non-piezoelectric layer and the proximate end of the piezoelectric layer extends beyond the proximate end of the non-piezoelectric layer.

FIG. 7 is an illustration of an example configuration of a self-exciting, self-sensing piezoelectric cantilever sensor having two base portions.

FIG. 8 is an illustration of another example configuration of a self-exciting, self-sensing piezoelectric cantilever sensor, wherein the piezoelectric layer is not attached to either base portion.

FIG. 9 is an illustration of an example configuration of a self-exciting, self-sensing piezoelectric cantilever sensor having the piezoelectric layer anchored at two ends.

FIG. 10 is an illustration of an example configuration of a self-exciting, self-sensing piezoelectric cantilever sensor wherein the piezoelectric layer comprises two portions, one of which is anchored.

FIG. 11 is another illustration of an example configuration of a self-exciting, self-sensing piezoelectric cantilever sensor wherein the piezoelectric layer comprises two portions, one of which is anchored.

FIG. 12 is an illustration of an example configuration of a self-exciting, self-sensing piezoelectric cantilever sensor wherein the piezoelectric layer comprises two portions, neither which is anchored.

FIG. 13 is an illustration of an example configuration of a self-exciting, self-sensing piezoelectric cantilever sensor having an anchored non-piezoelectric portion and a non-anchored piezoelectric portion.

FIG. 14 is an illustration of an example configuration of a self-exciting, self-sensing piezoelectric cantilever sensor, wherein the non-piezoelectric layer is not attached to either base portion.

FIG. 15 is illustration of another example configuration of a self-exciting, self-sensing piezoelectric cantilever sensor wherein the piezoelectric portion has a different width than the piezoelectric portion.

FIG. 16 is an illustration of an example configuration of a self-exciting, self-sensing piezoelectric cantilever sensor comprising a piezoelectric layer and a non-piezoelectric layer, wherein the width, of the piezoelectric layer is less than the width of the non-piezoelectric layer 16, and the distal end of the piezoelectric layer extends beyond the distal end of the non-piezoelectric layer and the proximate end of the piezoelectric layer extends beyond the proximate end of the non-piezoelectric layer.

FIG. 17 is a flow diagram of an example process for detecting an analyte utilizing the self-exciting, self-sensing piezoelectric cantilever sensor.

FIG. 18 is a plot of an example resonance spectrum of the configuration of the self-exciting, self-sensing piezoelectric cantilever sensor depicted in FIG. 1, operated in air.

Claims

1. A cantilever sensor comprising: a piezoelectric layer comprising a proximate end and a distal end;a base portion coupled to the proximate end of the piezoelectric layer;a non-piezoelectric layer comprising a proximate end and a distal end, wherein at least a portion of the piezoelectric layer is coupled to at least a portion of the non-piezoelectric layer such that the piezoelectric layer and the non-piezoelectric layer are not coextensive; andelectrodes operatively associated with the piezoelectric layer.

2. A sensor in accordance with claim 1, wherein: the distal end of the non-piezoelectric layer extends beyond the distal end of the piezoelectric layer; andthe proximate end of the piezoelectric layer extends beyond the proximate end of the non-piezoelectric layer.

3. A sensor in accordance with claim 1, wherein: the distal end of the non-piezoelectric layer is flush with the distal end of the piezoelectric layer; andthe proximate end of the piezoelectric layer extends beyond the proximate end of the non-piezoelectric layer.

4. A sensor in accordance with claim 1, wherein: the distal end of the piezoelectric layer extends beyond the distal end of the non-piezoelectric layer; andthe proximate end of the piezoelectric layer extends beyond the proximate end of the non-piezoelectric layer.

5. A sensor in accordance with claim 1, wherein the non-piezoelectric layer comprises at least one of glass, a ceramic, a metal, a polymer, and a polymer and a ceramic composite.

6. A sensor in accordance with claim 1, wherein the non-piezoelectric layer comprises at least one of silicon dioxide, copper, stainless steel, and titanium.

7. A sensor in accordance with claim 1, wherein the piezoelectric layer comprises at least one of lead zirconate titanate, lead magnesium niobate-lead titanate solid solutions, strontium lead titanate, quartz silica, piezoelectric ceramic lead zirconate and titanate (PZT), and a piezoceramic-polymer fiber composite.

8. A sensor in accordance with claim 1, wherein a length of the non-piezoelectric layer is in a range of about 0.1 mm to about 10.0 mm.

9. A sensor in accordance with claim 1, wherein a length of the piezoelectric layer is in a range of about 0.1 mm to about 10.0 mm.

10. A sensor in accordance with claim 1, wherein a width of the non-piezoelectric layer is in a range of about 0.1 mm to about 4.0 mm.

11. A sensor in accordance with claim 1, wherein a width of the piezoelectric layer is in a range of about 0.1 mm to about 4.0 mm.

12. A sensor in accordance with claim 1, wherein at least one physical dimension of at least one of the piezoelectric layer and the non-piezoelectric layer is non-uniform.

13. A sensor in accordance with claim 1, wherein the electrodes are utilized to measure a resonance frequency of the sensor.

14. A sensor in accordance with claim 13, wherein the measured resonance frequency is indicative of an amount of analyte accumulated on the sensor.

15. A sensor in accordance with claim 1, wherein: oscillation associated stress is concentrated in the piezoelectric layer near the base portion; andthe electrodes are positioned proximate to a location of the concentrated stress.

16. A cantilever sensor comprising: a piezoelectric layer comprising a proximate end and a distal end;a non-piezoelectric layer comprising a proximate end and a distal end, wherein at least a portion of the piezoelectric layer is coupled to at least a portion of the non-piezoelectric layer such that the piezoelectric layer and the non-piezoelectric layer are not coextensive;a first base portion coupled to one of the piezoelectric layer and the non-piezoelectric layer;a second base portion coupled to one of the piezoelectric layer and the non-piezoelectric layer; andelectrodes operatively associated with the piezoelectric layer.

17. A sensor in accordance with claim 16, wherein: the proximate end of the non-piezoelectric layer is coupled to the first base portion;the distal end of the non-piezoelectric layer is coupled to the second base portion;the proximate end of the piezoelectric layer is coupled to the first base portion; andthe distal end of the non-piezoelectric layer extends beyond the distal end of the piezoelectric layer.

18. A sensor in accordance with claim 16, wherein: the proximate end of the non-piezoelectric layer is coupled to the first base portion;the distal end of the non-piezoelectric layer is coupled to the second base portion;the distal end of the non-piezoelectric layer extends beyond the distal end of the piezoelectric layer; andthe proximate end of the non-piezoelectric layer extends beyond the proximate end of the piezoelectric layer.

19. A sensor in accordance with claim 16, wherein: the piezoelectric layer comprises a first piezoelectric portion and a second piezoelectric portion;the first piezoelectric portion comprises a proximate end and a distal end;the second piezoelectric portion comprises a proximate end and a distal end;the proximate end of the non-piezoelectric layer is coupled to the first base portion;the distal end of the non-piezoelectric layer is coupled to the second base portion;the proximate end of the first piezoelectric portion is coupled to the first base portion;the distal end of the second piezoelectric portion is coupled to the second base portion; andthe distal end of the first piezoelectric portion and the proximate end of the second piezoelectric portion form a space therebetween.

20. A sensor in accordance with claim 16, wherein: the piezoelectric layer comprises a first piezoelectric portion and a second piezoelectric portion;the first piezoelectric portion comprises a proximate end and a distal end;the second piezoelectric portion comprises a proximate end and a distal end;the proximate end of the non-piezoelectric layer is coupled to the first base portion;the distal end of the non-piezoelectric layer is coupled to the second base portion;the proximate end of the first piezoelectric portion is coupled to the first base portion; andthe distal end of the first piezoelectric portion and the proximate end of the second piezoelectric portion form a space therebetween.

21. A sensor in accordance with claim 16, wherein: the piezoelectric layer comprises a first piezoelectric portion and a second piezoelectric portion;the first piezoelectric portion comprises a proximate end and a distal end;the second piezoelectric portion comprises a proximate end and a distal end;the proximate end of the non-piezoelectric layer is coupled to the first base portion;the distal end of the non-piezoelectric layer is coupled to the second base portion; andthe distal end of the first piezoelectric portion and the proximate end of the second piezoelectric portion form a space therebetween.

22. A sensor in accordance with claim 16, wherein: the proximate end of the piezoelectric layer is coupled to the first base portion;the distal end of the non-piezoelectric layer is coupled to the second base portion;the distal end of the non-piezoelectric layer extends beyond the distal end of the piezoelectric layer; andthe proximate end of the piezoelectric layer extends beyond the proximate end of the non-piezoelectric layer.

23. A sensor in accordance with claim 16, wherein: the proximate end of the piezoelectric layer is coupled to the first base portion;the distal end of the piezoelectric layer is coupled to the second base portion;the distal end of the piezoelectric layer extends beyond the distal end of the non-piezoelectric layer; andthe proximate end of the piezoelectric layer extends beyond the proximate end of the non-piezoelectric layer.

24. A sensor in accordance with claim 16, wherein the non-piezoelectric layer comprises at least one of glass, a ceramic, a metal, a polymer, and a polymer and a ceramic composite.

25. A sensor in accordance with claim 16, wherein the non-piezoelectric layer comprises at least one of silicon dioxide, copper, stainless steel, and titanium.

26. A sensor in accordance with claim 16, wherein the piezoelectric layer comprises at least one of lead zirconate titanate, lead magnesium niobate-lead titanate solid solutions, strontium lead titanate, quartz silica, piezoelectric ceramic lead zirconate and titanate (PZT), and a piezoceramic-polymer fiber composite.

27. A sensor in accordance with claim 16, wherein a length of the non-piezoelectric layer is in a range of about 0.1 mm to about 10.0 mm.

28. A sensor in accordance with claim 16, wherein a length of the piezoelectric layer is in a range of about 0.1 mm to about 10.0 mm.

29. A sensor in accordance with claim 16, wherein a width of the non-piezoelectric layer is in a range of about 0.1 mm to about 4.0 mm.

30. A sensor in accordance with claim 16, wherein a width of the piezoelectric layer is in a range of about 0.1 mm to about 4.0 mm.

31. A sensor in accordance with claim 16, wherein at least one physical dimension of at least one of the piezoelectric layer and the non-piezoelectric layer is non-uniform.

32. A sensor in accordance with claim 16, wherein the electrodes are utilized to measure a resonance frequency of the sensor.

33. A sensor in accordance with claim 32, wherein the measured resonance frequency is indicative of an amount of analyte accumulated on the sensor.

34. A sensor in accordance with claim 16, wherein: oscillation associated stress is concentrated at a location in the piezoelectric layer; andthe electrodes are positioned proximate to the location of the concentrated stress.

35. A method for detecting an analyte, the method comprising: providing a cantilever sensor comprising: a piezoelectric layer;at least one base portion coupled to at least one of the piezoelectric layer and the non-piezoelectric layer;a non-piezoelectric layer, wherein at least a portion of the piezoelectric layer is coupled to at least a portion of the non-piezoelectric layer such that the piezoelectric layer and the non-piezoelectric layer are not coextensive; andelectrodes operatively associated with the piezoelectric layer.exposing at least a portion of the non-piezoelectric layer to a medium;measuring, via the electrodes, a resonance frequency of the sensor;comparing the measured resonance frequency with a baseline resonance frequency;if the measured resonance frequency differs from the baseline resonance frequency, determining that an analyte is present in the medium.

36. A method in accordance with claim 35, wherein the baseline resonance frequency is a resonance frequency of the sensor having no analyte accumulated thereon.

37. A method in accordance with claim 35, wherein medium comprises one of a liquid, a gas, and a vacuum.

38. A method in accordance with claim 35, wherein the analyte comprises at least one of a bioterrorism agent, a food-borne pathogen, a water pathogen, a cell type in a body fluids, a biomarker in a body fluid, an indication of an explosive material, an airborne toxin, a waterborne toxin, and a biological entity.

39. A method in accordance with claim 35, further comprising determining an amount of analyte accumulated on the sensor in accordance with the difference between the measured resonance frequency and the baseline resonance frequency.

40. A method in accordance with claim 35, further comprising determining a change in an amount of mass of an analyte accumulated on the sensor in accordance with the difference between the measured resonance frequency and the baseline resonance frequency, wherein a 1 Hertz difference between the measured resonance frequency and the baseline resonance frequency is indicative of a change is mass of about 100 attograms.

41. A method in accordance with claim 35, further comprising detecting a presence of an analyte in the medium, wherein the analyte comprises at least one of a protein, a lipoprotein, DNA, and RNA in the medium at a concentration of 1 femtograms per mL.

42. A method in accordance with claim 35, further comprising detecting a presence of an analyte in the medium, wherein the analyte comprises a pathogen in the medium at a concentration of 1 pathogen per mL.

43. A method in accordance with claim 35, wherein a difference in the measured resonance frequency and the baseline resonance frequency is indicative of a stress in the piezoelectric layer.

44. A method in accordance with claim 35, wherein oscillation associated stress is concentrated at a location in the piezoelectric layer, the method further comprising positioning the electrodes proximate to the location of the concentrated stress.