Embedded piezoelectric microcantilever sensors

• US 20070119236A1
• Filed: 01/24/2007
• Published: 05/31/2007
• Est. Priority Date: 12/02/2004
• Status: Active Grant

• Current Assignee: Michael Eastman, Timothy Porter
• Original Assignee: Michael Eastman, Timothy Porter
• Inventors: Eastman, Michael, Porter, Timothy
• Granted Patent: US 7,395,693 B2
• Time in Patent Office: Days
• US Class Current: 73/31.50
• CPC Class Codes: G01N 2203/0023 Bending
• CPC Class Codes: G01N 2203/0286 Miniature specimen; Testing on microregions of a specimen
• CPC Class Codes: G01N 7/04 by absorption or adsorption alone

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 sensing material having at least one receptor bound to said sensing material that selectively binds an analyte, wherein said sensing material undergoes a volumetric change when brought into contact with said analyte;

a deflectable arm having a first end fixedly coupled to a substrate, and a second end capable of deflecting responsive to a volumetric change of the sensing material deposit; and

a detecting element which creates a detectable signal in response to the deflection of said arm.

2. The microcantilever sensor as in claim 1, wherein said arm includes at least one measurable physical property which changes when said arm deflects and said detecting element is capable of measuring a change in said at least one measurable physical property at least one point alone said arm.

3. The microcantilever sensor as in claim 1, 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 1, 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 1, in which said deflectable arm includes a piezoresistive member formed one of therein or thereon 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 1, in which said sensing material deposit is disposed on a further substrate.

8. The microcantilever sensor as in claim 1, wherein said sensing material deposit is formed on a surface and said deflectable arm is embedded within said sensing material deposit.

9. The microcantilever sensor as in claim 1, wherein said sensing material deposit comprises a polymer matrix.

10. The microcantilever sensor as in claim 1, wherein the sensing material deposit comprises a biological receptor formed of one of either layered biological molecules or composite materials.

11. The microcantilever sensor as in claim 10, in which said biological receptor comprises one of either an antibody or a composite containing said antibody.

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

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

14. The microcantilever sensor as in claim 13, in which said genetic material is DNA and the at least one analyte comprises the complementary DNA strand of double-stranded DNA.

15. The microcantilever sensor as in claim 9, wherein said polymer matrix comprises at least one material selected from the group consisting of polyvinyl acetate (PVA), polylsobutylene (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).

20. 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 at a plurality of locations along said arm.

16. A method for detecting an analyte within a medium, comprising:

providing a deflectable microcantilever arm having a first end fixedly coupled to a substrate, said microcantilever arm disposed in a rest position;

forming a sensing material deposit adjacent to a second end of said arm;

binding a receptor material capable of selectively binding an analyte to said sensing material, such that said sensing material deposit is capable of a volumetric change responsive to the presence of said analyte, said volumetric change causing a deflection of said microcantilever arm;

measuring a control volume of said sensing material deposit by monitoring the deflection of said microcantilever arm in the absence of said analyte;

introducing a medium containing said analyte to said sensing element, said medium being one of a liquid and a vapor; and

comparing the control volume to a measured volume in the presence of said medium by monitoring said deflection of said microcantilever arm.

17. The method as in claim 16, wherein said microcantilever arm includes at least one measurable physical property which changes when said microcantilever arm deflects and said measuring comprises measuring a change in said at least one measurable physical property.

18. The method as in claim 16, wherein said microcantilever arm includes a piezoresistive member one of therein and thereon, and said measuring comprises measuring a resistance change of said piezoresistive member as a result of one of said upward deflection and said downward deflection.

19. The method as in claim 18, in which said microcantilever arm includes two conductive leads coupled to said piezoresistive member and said measuring includes measuring resistance across said two conductive leads.