ACCESSIBLE STRESS-BASED ELECTROSTATIC MONITORING OF CHEMICAL REACTIONS AND BINDING

• US 20090320606A1
• Filed: 06/27/2008
• Published: 12/31/2009
• Est. Priority Date: 06/27/2008
• Status: Active Grant

• Current Assignee: Charles Stark Draper Laboratory Incorporated
• Original Assignee: Charles Stark Draper Laboratory Incorporated
• Inventors: Uhland, Angela Z., Carlen, Edwin, Aceti, John, Weinberg, Marc S., Bernstein, Jonathan, Tupper, Malinda M.
• Granted Patent: US 8,181,531 B2
• Time in Patent Office: Days
• US Class Current: 73/718
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm
• CPC Class Codes: H01L 29/84 controllable by variation of applied mechanical force, e.g. of pressure

Abstract

A sensor may include a substrate that has a cavity formed in a surface thereof. A diaphragm, having a conductive portion, may be suspended over the cavity, a selective coating may be present on a face of the diaphragm outside of the cavity, and a counterelectrode may be spaced from and in opposition to the diaphragm. The diaphragm may deform upon interaction of the selective coating with an analyte and thereby alter a capacitance of the sensor in a manner indicative of a degree of interaction.

Claims

1. A sensor comprising:

a substrate having a first cavity formed in a first surface thereof;

a diaphragm suspended over the first cavity and comprising a conductive portion;

a selective coating on a first face of the diaphragm outside of the first cavity; and

a counterelectrode spaced from and in opposition to the diaphragm,

wherein the diaphragm deforms upon interaction of the selective coating with an analyte and thereby alters a capacitance of the sensor in a manner indicative of a degree of interaction.

2. The sensor of claim 1 further comprising means for equalizing a pressure on each of the first face and a second face of the diaphragm.

3. The sensor of claim 2, wherein the pressure-equalizing means comprises perforations through the counterelectrode.

4. The sensor of claim 2, wherein the pressure-equalizing means comprises a release channel in communication with the first cavity.

5. The sensor of claim 4, wherein the release channel is formed through the substrate.

6. The sensor of claim 4, wherein the release channel is positioned between the diaphragm and the first surface of the substrate.

7. The sensor of claim 1 further comprising a wall member coupled to the diaphragm such that a fluidic channel is formed between the diaphragm and the wall member.

8. The sensor of claim 7, wherein the wall member comprises a polymer.

9. The sensor of claim 1 further comprising electronic circuitry for detecting presence of the analyte.

10. The sensor of claim 1 further comprising electronic circuitry for measuring a concentration of the analyte based at least in part on the capacitance.

11. The sensor of claim 1, wherein a second cavity is formed in a second surface of the substrate.

12. The sensor of claim 1, wherein the counterelectrode is positioned within the first cavity.

13. The sensor of claim 1 further comprising through-wafer interconnects coupled to the substrate.

14. The sensor of claim 1, wherein the substrate comprises glass.

15. The sensor of claim 1, wherein the selective coating comprises at least one of a polypeptide, an antibody, or an antigen.

16. A method of detecting binding to or reaction with a selective material, the method comprising:

a) providing a sensor comprising;

i) a substrate having a first cavity formed in a first surface thereof;

ii) a diaphragm suspended over the first cavity and comprising a conductive portion;

iii) a selective coating on a first face of the diaphragm outside of the first cavity; and

iv) a counterelectrode spaced from and in opposition to the diaphragm,

wherein the diaphragm deforms upon interaction of the selective coating with an analyte and thereby alters a capacitance of the sensor; and

b) measuring the sensor capacitance to determine a degree of interaction between the analyte and the selective coating.

17. The method of claim 16, wherein measuring the sensor capacitance comprises comparing the sensor capacitance to a reference capacitance.

18. The method of claim 17, wherein the reference capacitance is substantially equal to the sensor capacitance in the absence of the interaction.

19. The method of claim 16 further comprising exposing the selective coating to a fluid.

20. The method of claim 19 further comprising applying a voltage to the diaphragm to counteract deformation induced in the diaphragm by a charge from the fluid.

21. The method of claim 20 further comprising determining, from the measurement of the sensor capacitance, whether an analyte that binds to the coating is present in the fluid.

22. A method of fabricating a sensor, the method comprising:

forming a first cavity in a first surface of a substrate;

forming a counterelectrode in the first cavity;

suspending, over the first cavity, a flexible diaphragm comprising a conductive portion; and

applying a selective coating, for interaction with an analyte, to a first face of the diaphragm outside of the first cavity.

23. The method of claim 22 further comprising:

forming a second cavity in a second surface of the substrate; and

forming holes in the substrate to fluidly connect the first and second cavities.

24. The method of claim 22 further comprising forming a release channel to vent the first cavity.

25. The method of claim 22 further comprising coupling a wall member to the flexible diaphragm to form a fluidic channel between the diaphragm and the wall member.