Enhanced detection sensitivity with piezoelectric sensors
A method for enhancing the detection sensitivity of a piezoelectric microcantilever sensor. The method may involve providing a piezoelectric microcantilever and inducing a change in the Young's modulus during detection of a species of interest. The change in the Young's modulus may be induced or enhanced by the application of a DC bias electric field to the piezoelectric layer that enhances non-180° polarization domain switching of the piezoelectric layer. The change in the Young's modulus may also result from binding of the species of interest to the piezoelectric microcantilever sensor or a combination of binding and application of a DC bias electric field Significantly enhanced detection sensitivity results from the changed Young's modulus of the piezoelectric layer.
1. A method for using a piezoelectric sensor comprising the steps of:
inducing a change in the Young's modulus of a piezoelectric layer by non-180° polarization domain switching in said piezoelectric layer of the piezoelectric sensor, and
detecting a species of interest by measuring a frequency shift of said piezoelectric layer having a changed Young's modulus, wherein said frequency shift is caused by binding of said species of interest to receptors on said piezoelectric sensor.
2. A method as claimed in claim 1 , wherein said detecting step is carried out with application of a DC bias electric field to said piezoelectric sensor.
3. The method claim 2 , wherein the DC bias electric field is from about −20 kV/cm to about 20 kV/cm.
4. The method claim 1 , wherein the piezoelectric layer is selected from the group consisting of PZT, PMN-PT and NKN-LN.
5. The method claim 1 , wherein the piezoelectric layer has a thickness of from about 0.5 μm to about 250 μm.
6. The method claim 1 , wherein the piezoelectric layer has a thickness of from about 0.5 μm to about 127 μm.
7. The method claim 1 , wherein the piezoelectric layer has a thickness of from about 0.5 μm to about 100 μm.
8. The method claim 1 , wherein the piezoelectric layer has a piezoelectric coefficient −d 31 of about 20 pm/V to about 5000 pm/V.
9. The method claim 1 , wherein the piezoelectric layer has a piezoelectric coefficient −d 31 greater than about 20 pm/V.
10. The method claim 1 , wherein the piezoelectric layer has a piezoelectric coefficient d 33 greater than about 40 pm/V.
11. The method claim 1 , wherein the piezoelectric sensor further comprises an electrical insulation layer which enables the sensor to substantially withstand liquid damping.
12. The method claim 1 , wherein the piezoelectric sensor may further comprise a non-piezoelectric layer selected from the group consisting of: a metal, a ceramic and a plastic layer.
13. The method claim 1 , wherein during the detection step the piezoelectric sensor is operated in a mode selected from the group consisting of: flexural mode and longitudinal mode.
14. The method claim 13 , wherein during the detection step, the piezoelectric sensor is operated in a longitudinal mode selected from the group consisting of: length mode, width mode or thickness mode.
15. The method claim 2 , wherein the DC bias electric field is from about −10 kV/cm to about 10 kV/cm.
16. The method of claim 1 , wherein said change in the Young's modulus is from about 25% to about 70%.
17. The method of claim 16 , wherein said change in the Young's modulus is induced by binding of the species of interest to receptors on said piezoelectric sensor.
18. The method of claim 1 , wherein the piezoelectric sensor is a piezoelectric microcantilever sensor.
19. The method of claim 1 , wherein the sensor is immersed in a flowing liquid during said detecting step.
20. The method of claim 9 , wherein the piezoelectric layer has a piezoelectric coefficient d 33 greater than about 40 pm/V, and a thickness of from about 0.5 μm to about 250 μm.
21. The method of claim 20 , wherein said detecting step is carried out with application of a DC bias electric field to said piezoelectric sensor.
22. The method claim 21 , wherein the DC bias electric field is from about −20 kV/cm to about 20 kV/cm.