Silicon Electrochemical Sensors

• US 20080302660A1
• Filed: 03/14/2008
• Published: 12/11/2008
• Est. Priority Date: 06/07/2007
• Status: Active Grant

• Current Assignee: Sensor Innovations, Inc.
• Original Assignee: Sensor Innovations, Inc.
• Inventors: Norviel, Vern, Wong, Elicia, Kahn, Carolyn R.
• Granted Patent: US 8,197,650 B2
• Time in Patent Office: Days
• US Class Current: 204/416
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: C09K 2323/023 Organic silicon compound, e.g. organosilicon
• CPC Class Codes: C12M 41/32 of substances in solution
• CPC Class Codes: G01N 27/407 for investigating or analysing gases G01N27/411 takes precedence
• CPC Class Codes: G01N 27/4167 pH electrodes therefor G01N27/302, G01N27/36
• CPC Class Codes: Y10T 428/24421 Silicon containing
• CPC Class Codes: Y10T 428/2995 Silane, siloxane or silicone coating

Abstract

Described herein are substrates, sensors and systems related to measuring the concentration of an analyte such as hydrogen ion in a sample. Redox active moieties whose reduction and/or oxidation potentials are sensitive to the presence of an analyte are immobilized onto a silicon surface. Immobilized redox active moieties whose reduction and/or oxidation potential are insensitive to the analyte can be used for reference. Voltammetric measurements made using such modified silicon surfaces can accurately determine the presence and/or concentrations of analytes in a sample of interest. The silicon electrochemical sensors of the invention are robust and can be made so as not to require calibration or re-calibration.

Claims

1-22. -22. (canceled)

23. A sensor for detecting the presence of an analyte comprising:

a silicon electrode having a silicon surface having immobilized thereon a redox-active moiety, wherein the redox-active moiety exhibits an oxidation potential and/or a reduction potential that is sensitive to the presence of said analyte.

24. The sensor of claim 23 wherein the analyte is hydrogen ion and the redox-active moiety is sensitive to hydrogen ion concentration.

25. The sensor of claim 23 wherein the sensor comprises a plurality of redox-active moieties, wherein at least one of the redox-active moieties is sensitive to the presence of an analyte, and at least one other redox-active moiety is substantially insensitive to the presence of said analyte.

26. The sensor of claim 25 wherein the analyte is hydrogen ion, and the moiety that is substantially insensitive to the presence of hydrogen ion has a substituent selected from the group consisting of ferrocene, polyvinylferrocene, viologen, polyviologen, and polythiophene.

27. The sensor of claim 26 wherein the moiety that is substantially insensitive to the presence of hydrogen ion is ferrocene or a derivative of ferrocene.

28. The sensor of claim 25 wherein the analyte is hydrogen, and the redox-active moiety that is sensitive to the presence of the hydrogen ion comprises a substituent selected from the group consisting of anthracenes, quinones, anthroquinones, phenanthroquinones, phenylene diamines, catechols, phenothiazinium dyes, monoquaternized N-alkyl4,4′

-bipyridinium, RuO_x, and Ni(OH)₂.

29. The sensor of claim 28 wherein the redox-active moiety that is sensitive to the presence of hydrogen ion comprises a substituent comprising anthracene.

30. The sensor of claims 28 wherein the redox-active moiety that is sensitive to the presence of hydrogen ion comprises a substituent comprising an anthraquinone or a phenanthraquinone.

31. The sensor of claim 25 wherein the redox-active moiety that is sensitive to the presence of an analyte is sensitive to the concentration of the analyte.

32. The sensor of claim 31 wherein the oxidation potential and/or reduction potential of the redox-active moiety is sensitive to the concentration of the analyte in a range from about 10⁻

3 M to about 10<sup>−

10</sup> M.

33. The sensor of claim 31 wherein the oxidation potential and/or reduction potential of the redox-active moiety is sensitive to the concentration of the analyte in a range from about 10⁻

2 M to about 10<sup>−

13</sup> M.

34. The sensor of claim 31 wherein the sensor detects hydrogen ion concentration from about pH3 to about pH 10.

35. The sensor of claim 31 wherein the sensor detects hydrogen ion concentration from about pH² to about pH13.

36. The sensor of claim 31 wherein the sensor measures hydrogen ion concentration within an accuracy of about plus or minus 0.1 pH unit.

37. The sensor of claim 31 wherein the sensor measures hydrogen ion concentration within an accuracy of about plus or minus 0.01 pH units.

38. The sensor of claim 23 wherein the redox-active moiety is covalently bound to the surface of the electrode.

39. The sensor of claim 23 wherein the redox-active moiety is bound to a polymer that is immobilized onto the surface of the electrode.

40. The sensor of claim 23 wherein the silicon electrode is doped.

41. The sensor of claim 40 wherein the silicon electrode is p-doped.

42. The sensor of claim 41, wherein the silicon electrode is doped with boron.

43. The sensor of claim 40 wherein the silicon electrode is n-doped

44. The sensor of claim 43, wherein the silicon electrode is doped with phosphorous.

45. The sensor of claim 23 wherein the electrode comprises a monolithic piece of silicon.

46. The sensor of claim 23 wherein the silicon electrode comprises a composite electrode, said composite electrode comprising silicon particles in a matrix.

47. The sensor of claim 46, wherein the silicon electrode comprises a composite electrode bound to a conductive substrate.

48. The sensor of claim 46 wherein the silicon particles are present in an amount such that a conductive path is created across the composite electrode.

49. The sensor of claim 23 wherein the electrode comprises porous silicon.

50. The sensor of claim 23 wherein the electrode comprises unpolished silicon.

51. The sensor of claim 23 wherein the electrode comprises polished silicon.

52. The sensor of claim 23 wherein the silicon electrode has a resistivity within the range of about 0.01 to about 1000 Ω

-cm.

53. The sensor of claim 23 wherein the silicon electrode has a resistivity within the range of about 1 to about 100 Ω

-cm.

54. The sensor of claim 25 wherein the sensor is capable of measuring analyte concentration without calibration with an external standard.

55. The sensor of claim 54 wherein the sensor remains sensitive to the analyte without calibration after a first use by an end user.

56. The sensor of claim 54 wherein the analyte is hydrogen ion and the sensor remains sensitive to hydrogen ion after exposure to a cell culture medium for at least about 6 days.

57. The sensor of claim 56 wherein the sensor is capable of measuring pH with an accuracy of about plus or minus 0.2 units after exposure to the cell culture medium for at least about 6 days.

58. The sensor of claim 54 wherein the analyte is hydrogen ion and the sensor is capable of measuring pH with an accuracy of about plus or minus 0.2 units after autoclave treatment at 121°

C. for 40 minutes.

59. The sensor of claim 58 wherein the sensor is capable of measuring pH with an accuracy of about plus or minus 0.2 units after autoclave treatment at 121°

C. for 400 minutes.

60-80. -80. (canceled)

81. An analyte-sensing system comprising:

(a) a working electrode having a silicon surface that has immobilized thereon a redox-active moiety, wherein the redox-active moiety has an oxidation potential and/or reduction potential that is sensitive to the presence of said analyte;

(b) a counter electrode and optionally a reference electrode;

(c) a source for supplying a plurality of potentials to the working electrode; and

(d) a device for measuring current through the working electrode at the plurality of potentials.

82. The system of claim 81, wherein the silicon surface also has immobilized thereon a second redox-active moiety having an oxidation potential and/or reduction potential that is insensitive to the presence of said analyte.

83. The system of claim 81 wherein the source for supplying a plurality of potentials is a potentiostat capable of applying square waves for square wave voltammetry.

84. The system of claim 81 further comprising a computation system that communicates with the device for measuring current, having algorithms for calculating reduction or oxidation potential from the measured current at a plurality of potentials.

85. The system of claim 81 wherein the system is used as an in-line sensor in a process.

86. The system of claim 85 wherein the currents measured at a plurality of potentials are used to determine analyte concentration, and the determined analyte concentration is used to control a process parameter.

87-100. -100. (canceled)

101. An sensing system for sensing more than one analyte comprising:

(a) a plurality of working electrodes, each having a silicon surface having immobilized thereon a redox-active moiety,

wherein the redox-active moiety has an oxidation potential and/or reduction potential that is sensitive to the presence of an analyte, wherein each working electrode is sensitive to a different analyte;

(b) a counter electrode and optionally a reference electrode;

(c) a source for supplying a plurality of potentials to the working electrode; and

(d) a device for measuring current through the working electrode at the plurality of potentials.

102. The system of claim 101, wherein each silicon surface also has immobilized thereon a second redox-active moiety having an oxidation potential and/or reduction potential that is insensitive to the presence of said analyte.

103. The sensing system of claim 101, wherein the analytes are hydrogen, ammonia, oxygen, or carbon dioxide.