Molecular control of surface coverage

• US 8,286,486 B2
• Filed: 05/10/2007
• Issued: 10/16/2012
• Est. Priority Date: 05/10/2006
• Status: Active Grant

• Current Assignee: Drexel University
• Original Assignee: Drexel University
• Inventors: Mutharasan, Rajakkannu, Delesdernier, David L., Rijal, Kishan
• Primary Examiner(s): Macchiarolo, Peter
• Assistant Examiner(s): BELLAMY, TAMIKO D
• Application Number:
  US12/299,841
• Publication Number:
  US 20100018310A1
• Time in Patent Office: 1,986 Days
• Field of Search: 735/79, 73/617.5, 73/73, 73/614.9, 73/240.1, 735/80, 73/645.3
• US Class Current: 73/579
• CPC Class Codes: G01N 2291/0256 Adsorption, desorption, surface mass change, e.g. on biosensors
• CPC Class Codes: G01N 29/036 by measuring frequency or resonance of acoustic waves
• CPC Class Codes: G01N 5/025 for determining moisture content

Abstract

The concentration of a material covering a surface is controlled via an equilibrium process. Equilibrium parameters such as a concentration of the provided material, the exposure time of the material to the surface, and the surface area of an attractor applied to the surface are determined utilizing a millimeter sized piezoelectric cantilever sensor. In an example embodiment, the material is provided at a low concentration to the surface until equilibrium is attained. The amount of material accumulated on the surface is determined utilizing the cantilever sensor. The surface area of the attractor and the measured amount of material are utilized to determine the amount of the attractor surface area having the material bound thereto. Knowledge of the equilibrium parameters allows controlled surface coverage of the material on the attractor for any application. The concentration of the material adsorbed on the surface is precisely determinable and repeatable.

Claims

1. A method for determining a surface coverage of a material, the method comprising:

providing a predetermined concentration of the material; and

exposing the surface to the provided material until equilibrium is established in a molecular reaction between the surface and the material, wherein;

the surface comprises a surface of a non-piezoelectric layer of a piezoelectric cantilever sensor, the piezoelectric 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 base portion coupled to the proximate end of the piezoelectric layer, wherein the base portion is not attached to the proximate end of the non-piezoelectric layer; and

electrodes operatively associated with the piezoelectric layer; and

equilibrium is determined in accordance an amount of mass of the material accumulated on the surface.

2. A method in accordance with claim 1, wherein:

equilibrium is determined by measuring a resonance frequency of the piezoelectric cantilever sensor; and

a resonance frequency of the piezoelectric cantilever sensor is indicative of an amount mass of the material accumulated on the surface.

3. A method in accordance claim 2, wherein equilibrium is established when a resonance frequency of the piezoelectric cantilever sensor subsequent to exposure to the material differs, by at least a predetermined amount, from a resonance frequency of the piezoelectric cantilever sensor prior to exposure to the material.

4. A method in accordance with claim 1, further comprising determining a concentration of the material on the surface in accordance with an amount of mass of the material accumulated on the surface.

5. A method in accordance with claim 1, further comprising determining a concentration of the material on the surface by measuring a resonance frequency of the piezoelectric cantilever sensor, wherein a resonance frequency of the piezoelectric cantilever sensor is indicative of an amount mass of the material accumulated on the surface.

6. A method in accordance claim 1, further comprising:

measuring a first resonance frequency of the piezoelectric cantilever sensor prior to exposure to the material;

measuring a second resonance frequency of the piezoelectric cantilever sensor subsequent to exposure to the material;

determining that a predetermined concentration of the material is on the surface if the second resonance frequency differs from the first resonance frequency by a predetermined amount.

7. A method in accordance with claim 1, further comprising a concentration of the material on the surface in accordance with:

the predetermined concentration of the material; and

an amount time the surface is exposed to the material.

8. A method in accordance with claim 1, further comprising:

providing predetermined concentrations of a plurality of materials; and

exposing the surface to the plurality of materials until equilibrium is established, respectively, in a molecular reaction between the surface and each one of the plurality of materials.

9. A method in accordance with claim 8, wherein each of the plurality of materials is sequentially exposed to the surface.

10. A method in accordance with claim 9, further comprising determining a respective concentration of each one of the plurality of materials on the surface in accordance with:

a respective predetermined concentration of each material; and

a respective amount time the surface is exposed to each material.

11. A method in accordance with claim 1, wherein equilibrium is indicative of a concentration of the material on the surface.

12. A system for determining a surface coverage of a material, the system comprising:

a piezoelectric 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 base portion coupled to the proximate end of the piezoelectric layer; and

the base portion is not attached to the proximate end of the non-piezoelectric layer;

an exposing portion configured to expose a predetermined concentration of the material to the surface until equilibrium is established in a molecular reaction between the surface and the material, wherein;

the surface comprises a surface of the non-piezoelectric layer of the piezoelectric cantilever sensor; and

equilibrium is determined in accordance an amount of mass of the material accumulated on the surface.

13. A system in accordance with claim 12, wherein:

equilibrium is determined by measuring a resonance frequency of the piezoelectric cantilever sensor; and

a resonance frequency of the piezoelectric cantilever sensor is indicative of an amount mass of the material accumulated on the surface.

14. A system in accordance claim 13, wherein equilibrium is established when a resonance frequency of the piezoelectric cantilever sensor subsequent to exposure to the material differs, by at least a predetermined amount, from a resonance frequency of the piezoelectric cantilever sensor prior to exposure to the material.

15. A system in accordance with claim 12, further comprising a processing portion configured to determine a concentration of the material on the surface in accordance with an amount of mass of the material accumulated on the surface.

16. A system in accordance with claim 12, further comprising a processing portion configured to determine a concentration of the material on the surface by measuring a resonance frequency of the piezoelectric cantilever sensor, wherein a resonance frequency of the piezoelectric cantilever sensor is indicative of an amount mass of the material accumulated on the surface.

17. A system in accordance claim 12, further comprising a processing portion configured to:

measure a first resonance frequency of the piezoelectric cantilever sensor prior to exposure to the material;

measure a second resonance frequency of the piezoelectric cantilever sensor subsequent to exposure to the material;

determine that a predetermined concentration of the material is on the surface if the second resonance frequency differs from the first resonance frequency by a predetermined amount.

18. A system in accordance with claim 12, further comprising a processing portion configured to determine a concentration of the material on the surface in accordance with:

the predetermined concentration of the material; and

an amount time the surface is exposed to the material.

19. A system in accordance with claim 12, further configured to:

expose predetermined concentrations of a plurality of materials to the surface until equilibrium is established, respectively, in a molecular reaction between the surface and each one of the plurality of materials.

20. A system in accordance with claim 19, wherein each of the plurality of materials is sequentially exposed to the surface.

21. A system in accordance with claim 20, further comprising a processing portion configured to determine a respective concentration of each one of the plurality of materials on the surface in accordance with:

a respective predetermined concentration of each material; and

a respective amount time the surface is exposed to each material.

22. A system in accordance with claim 12, wherein equilibrium is indicative of a concentration of the material on the surface.

23. A method for coating a surface with a material, the method comprising:

providing a predetermined concentration of the material; and

exposing the surface to the provided material for a predetermined amount of time, wherein;

the surface comprises a predetermined surface area of an attractor for attracting the material; and

within the predetermined amount of time, equilibrium is established in a molecular reaction between the attractor and the material; and

determining, utilizing a piezoelectric cantilever sensor, that an amount of the material attached to the attractor resulting from equilibrium is less than a total amount of material attractable to the attractor, the piezoelectric 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 base portion coupled to the proximate end of the piezoelectric layer, wherein the base portion is not attached to the proximate end of the non-piezoelectric layer.

24. A method in accordance with claim 23, further comprising sequentially exposing the surface to at least one other material, respectively, wherein each subsequent exposure results in coating an uncoated surface area of the attractor.

25. A method in accordance with claim 23, wherein the surface comprises a plurality of attractors for respectively attracting a plurality of materials.