Embedded piezoelectric microcantilever sensors

• US 7,168,294 B2
• Filed: 12/02/2004
• Issued: 01/30/2007
• Est. Priority Date: 06/03/2002
• Status: Expired due to Fees

• Current Assignee: Arizona Board of Regents (University of Arizona)
• Original Assignee: Arizona Board of Regents (University of Arizona)
• Inventors: Eastman, Michael P., Porter, Timothy L.
• Primary Examiner(s): CYGAN, MICHAEL T
• Application Number:
  US11/004,555
• Publication Number:
  US 20060053871A1
• Time in Patent Office: 789 Days
• Field of Search: 73/232, 73/240.6, 73/290.5, 73/310.1, 73/310.5
• US Class Current: 73/31.05
• CPC Class Codes: G01N 2291/0427 Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
• CPC Class Codes: G01N 29/022 Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices microdevices per se B81B
• CPC Class Codes: G01N 29/2475 Embedded probes, i.e. probes incorporated in objects to be inspected
• CPC Class Codes: G01N 33/54386 Analytical elements

Abstract

An apparatus and method for sensing chemical and/or biological analytes includes a deflectable arm of a microcantilever at least partially embedded within a sensing element. A gaseous or liquid medium which may include the analyte being detected is introduced to the sensing element. The sensing element undergoes volumetric expansion or contraction in the presence of the analyte sought to be detected, typically by adsorbing the analyte. The volumetric change of the sensing element causes the deflectable arm to deflect. The deflectable arm includes at least one measurable physical property which changes when the arm deflects. Detecting means are provided to measure the change in the physical property to determine the presence and amount of analyte present. An array of microcantilevers in which each microcantilever is dedicated to detecting a particular analyte which may be included in the medium, is also provided.

Claims

1. A microcantilever sensor, comprising:

a polymeric sensing material disposed on a substrate, said sensing material capable of a volumetric change in the presence of an analyte;

a deflectable arm having a first end fixedly coupled to a substrate, and a second end embedded in the polymeric sensing material, wherein said arm is capable of deflecting responsive to a volumetric change of the sensing material.

2. The microcantilever sensor as in claim 1, further comprising a detecting element that creates a detectable signal in response to deflection of said arm.

3. The microcantilever sensor as in claim 2, in which said detecting element includes an electric circuit for facilitating measurement of said deflection of said arm.

4. The microcantilever sensor as in claim 2, in which said detecting element includes a transducer capable of transducing said deflection of said arm to a measurable electrical signal.

5. The microcantilever sensor as in claim 2, in which said deflectable arm includes a piezoresistive member and said detecting element includes an electrical circuit capable of measuring a change in resistance of said piezoresistive member due to said deflection.

6. The microcantilever sensor as in claim 5, wherein said piezoresistive member comprises barium titanate.

7. The microcantilever sensor as in claim 2, wherein said detecting element is capable of measuring a change in said at least one measurable physical property in at least one point along said arm.

8. The microcantilever sensor as in claim 7, wherein said detecting element is capable of measuring a change in said at least one measurable physical property at a plurality of locations along said arm.

9. The microcantilever sensor as in claim 5, wherein said circuit includes two conductive leads coupled to said piezoresistive member and said detecting element measures resistance across said two conductive leads.

10. The microcantilever sensor as in claim 1, wherein the sensing material comprises a biological receptor.

11. The microcantilever sensor as in claim 10, in which said biological receptor comprises an antibody.

12. The microcantilever sensor as in claim 11, in which said analyte comprises a biological material attracted to said antibody.

13. The microcantilever sensor as in claim 12, wherein said biological material is one of either a genetic material or a virus.

14. The microcantilever sensor as in claim 10, in which said biological receptor comprises a genetic material either alone or contained within a composite material.

15. The microcantilever sensor as in claim 14, in which said genetic material is DNA and the analyte comprises a complementary DNA strand of double-stranded DNA.

16. The microcantilever sensor as in claim 15, wherein said analyte is a virus having a complementary nucleotide sequence.

17. The microcantilever sensor as in claim 1, wherein said arm includes at least one measurable physical property which changes when said arm deflects.

18. The microcantilever sensor as in claim 1, wherein said deflectable arm includes silicon nitride as a component thereof.

19. The microcantilever sensor as in claim 1, in which said analyte is included within one of either a gaseous medium or a liquid medium.

20. The microcantilever sensor as in claim 1, in which said deflectable arm includes a thickness ranging from 10 microns to 50 microns, a width ranging from 25 microns to 75 microns, and a length ranging from 100 microns to 200 microns.

21. The microcantilever sensor as in claim 1, wherein said polymeric sensing material is comprised of at least one material selected from the group consisting of polyvinyl acetate (PVA), polyisobutylene (PIB), polyethylene vinyl acetate (PEVA), poly(4-vinylphenol), poly(styrene-co-allyl alcohol), poly(methylstyrene), poly(N-vinylpyrrolidone), poly(styrene), poly(sulfone), poly(methyl methacrylate), and poly(ethylene oxide).

22. The microcantilever sensor as in claim 1, wherein the sensing material has a thickness of about 10 microns.

23. The microcantilever sensor as in claim 1, wherein the sensing material has a thickness of at least about 10 microns.

24. The microcantilever sensor as in claim 1, wherein the volumetric change is an increase in volume of the sensing material.

25. The microcantilever sensor as in claim 1, wherein the volumetric change is a decrease in volume of the sensing material.

26. The microcantilever sensor as in claim 1, wherein said analyte is a liquid or a vapor.

27. The microcantilever sensor as in claim 1, wherein said analyte is water vapor.