Nano-porous membrane based sensors

• US 20070256941A1
• Filed: 12/04/2006
• Published: 11/08/2007
• Est. Priority Date: 12/02/2005
• Status: Active Grant

• Current Assignee: State Of Oregon Acting By And Through The State Board Of Higher Education On Behalf Of Portland State University
• Original Assignee: German University, Oregon State University (Oregon University System)
• Inventors: Reddy, Ravi Kiran, Prasad, Shalini
• Granted Patent: US 8,409,411 B2
• Time in Patent Office: Days
• US Class Current: 205/775.500
• CPC Class Codes: G01N 27/26 by investigating electrochemical variables; by using electrolysis or electrophoresis
• CPC Class Codes: G01N 27/3278 involving nanosized elements, e.g. nanogaps or nanoparticles nanopores G01N33/48721; magnetic beads G01N27/745

Abstract

Sensors include nano-porous alumina membranes that are sensitized by immobilization of antibodies in the nano-pores. The nano-membranes can be sensitized to respond to a single target compound, or different portions of the nano-membrane can be differently sensitized. Capture of the target compound can be detected based on a spectral signature associated with electrical conductance in the nano-pores.

Claims

1. A sensor, comprising:

a substrate having defined therein at least one nano-porous membrane portion that includes a plurality of nano-pores;

a first conductor electrically coupled to a first set of nano-pores defined in the membrane; and

a first sensitizing agent immobilized at the first set of nano-pores.

2. The sensor of claim 1, further comprising:

a second conductor electrically coupled to a second set of nano-pores; and

a second sensitizing agent immobilized at the second set of nano-pores.

3. The sensor of claim 2, wherein the first sensitizing agent and the second sensitizing agent are the same.

4. The sensor of claim 2, wherein the first sensitizing agent and the second sensitizing agent are different.

5. The sensor of claim 1, further comprising a base substrate, wherein the first conductor is defined on the base substrate.

6. The sensor of claim 1, further comprising a spectrum analyzer in communication with the first conductor, the spectrum analyzer configured to produce an estimate of a received signal portion associated with a signature frequency.

7. The sensor of claim 6, wherein the spectrum analyzer is configured to produce an estimate of a received signal portion associated with at least two frequencies associated with a detection signature.

8. The sensor of claim 2, further comprising a spectrum analyzer that is selectively coupled to the first conductor and the second conductor, wherein the spectrum analyzer is configured to produce an estimate of a received signal portion associated with a frequency associated with a first signature and a frequency associated with a second signature.

9. The sensor of claim 8, wherein the spectrum analyzer is configured to produce an estimate of a received signal portion associated with at least two frequencies associated with the first signature and the second signature.

10. A method, comprising:

administering a test specimen to an assembly of nano-pores sensitized to a selected target compound; and

evaluating an electrical signal associated with administration of the test specimen to the nano-pores; and

assessing the test specimen based on the evaluation.

11. The method of claim 10, wherein the electrical signal is evaluated to identify a magnitude of at least one electrical spectral peak associated with exposure of the sensitized nano-pores to the target compound, and the test specimen is assessed based on the magnitude.

12. The method of claim 10, wherein the electrical signal is evaluated to identify an electrical signature associated with the target compound, and the test specimen is assessed based on the signature.

13. The method of claim 12, wherein the signature includes at least two electrical frequency components.

14. The method of claim 10, wherein the test specimen is administered to an assembly of nano-pores sensitized to at least a first target compound and a second target compound.

15. The method of claim 14, wherein a first electrical signal and a second electrical signal associated with a first set of nano-pores sensitized to the first target compound and a second set of nano-pores associated with the second target compound, respectively, are evaluated, and the test specimen is assessed based on electrical signatures associated with the first target compound and the second target compound.

16. The method of claim 15, wherein the first target compound is CRP and the second target compound is MPO.

17. The method of claim 15, wherein the electrical signal is evaluated to identify an electrical signature associated with the first target compound and the second target compound, and the test specimen is assessed based on the signature.

18. The method of claim 11, wherein the target compound is prostate specific antigen.

19. A sensor, comprising:

a first conductor electrically coupled to a first set of sensitized nano-pores; and

a signature analyzer electrically coupled to the first conductor, and configured to estimate at least one signature portion based on an electrical signal coupled from the first conductor.

20. The sensor of claim 19, wherein the signature portion is a signal magnitude in a selected frequency range.

21. The sensor of claim 19, further comprising a signature database, and the signature analyzer is configured to produce an indication of a presence of at least one analyte based on a comparison of the at least one signature portion with at least one stored signature.

22. An apparatus, comprising:

a base substrate having a plurality of conductor segments defined thereon;

a nano-porous membrane secured to the base substrate, the nano-porous membrane including a plurality of sets of sensitized nano-pores, the sets of nano-pores electrically coupled to corresponding conductor segments; and

a fluid chamber configured receive a test fluid and communicate the test fluid to the sets of sensitized nano-pores.

23. The apparatus of claim 22, wherein the nano-porous membrane is an alumina membrane having a plurality of nanopores with effective diameters in a range of 5 nm to 500 nm.

24. The apparatus of claim 23, wherein the first set of nano-pores has an effective diameter that is larger than an effective diameter of the second set of nano-pores.

25. The apparatus of claim 22, further comprising a spectrum analyzer configured to receive electrical signals from the conductor segments and produce spectra of the electrical signals.

26. A method, comprising:

selecting a pore size and a pore density;

selecting a composition, temperature, and current density of an electrolyte bath based on the selected pore size;

exposing an aluminum substrate to an electrolyte bath, and

anodizing the substrate with the selected a composition, temperature, and current density so as to produce nano-pores of the selected size and density.

27. The method of claim 26, further comprising:

selecting a first pore size and density and a second pore size density;

selecting a first and second composition, temperature, and current density of an electrolyte bath based on the selected pore sizes and densities;

anodizing a first portion of the aluminum substrate at the first composition, temperature, and current density and a second portion of the aluminum substrate at the second composition, temperature, and current density.

28. A method of producing a nanoporous alumina membrane, comprising:

providing an electrolyte bath at a predetermined temperature; and

increasing an extent to which an aluminum substrate is immersed in the electrolyte bath while varying a bath temperature or composition so as to produce nanopores with correspondingly variable pore sizes.

29. The method of claim 28, wherein the bath temperature and/or composition are varied in steps and the immersion of the aluminum substrate is increased in corresponding steps.

30. The method of claim 28, wherein the bath temperature and/or composition are varied substantially continuously.