Electrochemical process and apparatus to control the chemical state of a material

• US 4,139,348 A
• Filed: 11/28/1975
• Issued: 02/13/1979
• Est. Priority Date: 11/28/1975
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Swartz, Mitchell R.
• Primary Examiner(s): Wolk, Morris O.
• Assistant Examiner(s): Marcus, Michael S.
• Application Number:
  US05/636,290
• Time in Patent Office: 1,173 Days
• Field of Search: 356/41, 356/40, 128/2 L, 204/180 G, 204/195 B, 204/195 S, 204/1 P, 204/1 S, 204/1 T, 204/1 Y, 204/73 R, 204/160.1, 204/195 R, 204/195 T, 106/125, 106/136, 106/137, 357/8, 357/40, 23/232 E, 23/254 E, 23/255 E, 195/DIG. 11
• US Class Current: 436/35
• CPC Class Codes: A61N 2005/0644 Handheld applicators
• CPC Class Codes: A61N 2005/0651 Diodes
• CPC Class Codes: G01N 33/007 Arrangements to check the analyser calibrating gas analysers G01N33/0006

Abstract

Process and apparatus to control the chemical state of a material. Bulk control of the chemical state of such material which permits maintenance of chemicals including enzymes by both restoration and stabilization. Optical and electrical power sources act in the presence of chemical mediators to control the rate of charge transfer to substances including metals contained in proteins, for example. Controlled charge transfer to the proteins enables construction of devices including small molecule detectors, e.g., electrically restored ferrous deoxyhemoglobin in a discrete component electrooptical circuit to monitor, for example, oxygen and carbon monoxide partial pressures. Restoration of chemical activity in molecules which have deteriorated enables construction of chemical reactors composed of stabilized catalysts and enzymes, e.g., restored functional nitrogenase in solar energy conversion devices which evolve molecular hydrogen or in chemical reactors which convert molecular nitrogen into ammonia. Control of charge transfer to molecular oxygen enables dose related in situ production of superoxide anion and other free radicals. Oxygen ion control enables low voltage processes suitable for the sterilization of microorganisms, including viruses and neoplastic tissue, and the destruction of poisonous chemical including toxins and polychlorinated organic molecules.

Claims

1. A detector for sensing the presence of a molecular species of interest, that comprises, in combination:

a material whose properties change when said material is exposed to the molecular species of interest as a consequence of reversible binding of the molecular species, said material being subject to deterioration which affects the accuracy of the detector but which can be counteracted by injection of charge carriers into the energy bands of said material, means for detecting said change;

electric means serving as a source of charge carriers that are injected into said material to counteract the deterioration that occurs in said material, said material containing small amounts of an electroactive mediator to facilitate the charge transfer into the material; and

phonon generator means operable to direct very high frequency phonons into the material to facilitate acceptance of said charge carriers by the material.

2. A detector for sensing the presence and amount of a molecular species of interest, that comprises, in combination:

a sensing material whose properties change when said sensing material is exposed to the molecular species of interest as a consequence of reversible binding of the molecular species, said change occurring as a bulk change substantially over the whole volume of the sensing material, said sensing material being subject to deterioration which affects the accuracy of the detector but which can be counteracted by injection of charge carriers into the electronic states of said sensing material;

means for detecting said bulk change;

electric means serving as a source of charge carriers that are injected into said sensing material to counteract the deterioration that occurs in said sensing material;

an electroactive mediator intermixed in small amounts in the sensing material to form a composite material to facilitate the charge transfer into the sensing material; and

radiation means to irradiate said composite material to create excited electronic levels to permit and enhance charge carrier transfer into the electronic states of the sensing material.

3. A detector as claimed in claim 2 wherein said reversible binding is an oxygenation process, wherein said deterioration is an oxidation process, and wherein said charge carriers are electrons that are injected into the electronic states of said sensing material.

4. A detector as claimed in claim 2 wherein said electroactive mediator is taken from the group consisting essentially of dyes, quinones, free transition metals, and other conjugated π

-electron molecules as well as other elements and complexes with d^- and f^- electrons capable of moving between two or more electronic states.

5. A molecular species detector as claimed in claim 2 wherein said properties are a change in electromagnetic absorption at a specific wavelength and wherein said means for detecting notes changes in the electromagnetic absorption.

6. A detector as claimed in claim 2 wherein said properties are a change in the acoustic absorption at a specific wavelength or frequency.

7. A detector as claimed in claim 2 wherein said properties are a change in the magnetic characteristics of said material.

8. A detector as claimed in claim 2 wherein said properties are a change in the electrical characteristics of said material.

9. A detector as claimed in claim 2 wherein said electric means comprises an anode and a cathode and electric current source means connected to pass an electric current between the anode and the cathode and that has an ion exchange membrane disposed between the anode and the cathode to create a condition whereby substantially uniform charge injection into the sensing material occurs over most of the bulk of the sensing material in the volume between the anode and the cathode.

10. A detector as claimed in claim 2 wherein said electric means includes a pair of electrodes that act an an anode and a cathode and a source of electric energy connected to pass an electric current between the anode and the cathode, said sensing material being disposed between the anode and the cathode.

11. A detector as claimed in claim 10 wherein said electroactive mediator is taken from the group consisting essentially of dyes, quinones, free transition metals and other conjugated π

-electrons, and d and f electron systems.

12. A detector as claimed in claim 11 wherein said material includes a polymer that forms a matrix material.

13. A detector as claimed in claim 2 wherein the electric means includes electrode means to inject the charge carriers into the region occupied by the material, in which the electroactive mediator is one which permits charge carrier transfer in the presence of photons of a predetermined narrow band of radiation frequencies, and in which the radiation means is operable to irradiate the material with radiation within said narrow band.

14. A detector as claimed in claim 13 in which the electric means comprises a first electrode in electrical contact with the sensing material at a first region and a second electrode in electrical contact with the sensing material at a second region removed from the first region, said sensing material being disposed in the space between the first electrode and the second electrode.

15. A detector as claimed in claim 14 which further includes ion exchange membrane means that serves to render most of the volume between the first electrode and the second electrode effectively in a single electronic state so that said charge injection occurs substantially uniformly throughout said volume.

16. A detector as claimed in claim 15 wherein said deterioration is oxidation and in which said charge carriers are electrons.

17. A detector as claimed in claim 15 wherein said deterioration is reduction and in which said charge carriers are holes.

18. A detector as claimed in claim 15 in which said properties are a change in optical density of the material at a specific wavelength, in which said means for detecting comprises optical means for detecting the change in optical density, and in which the first electrode and the second electrode are disposed on an axis that is substantially orthogonal to the optical axis of the optical means.

19. A detector as claimed in claim 15 that further includes a current source connected to the first electrode and the second electrode to pass electric current through said material.

20. A detector as claimed in claim 2 wherein said properties are a change in optical density at a specific wavelength and wherein said means for detecting comprises means for detecting said change in optical density.

21. A detector as claimed in claim 20 in which said electroactive mediator acts to permit charge carrier transfer to the sensing material in the presence of photons of a narrow band of frequencies, in which the means for detecting said optical density changes comprises a light emitting diode disposed at one side of the material and a light detector sensitive to the frequencies emitted by the light emitting diode disposed to receive radiation from the light emitting diode after the radiation has passed through said material and to provide an electric signal as a function of the received radiation, and in which the light emitting diode radiates in said narrow band of frequencies.

22. A detector as claimed in claim 2 wherein said material contains metal atoms as an active element therein, wherein said deterioration is oxidation of the metal atoms, and wherein said charge carriers are electrons.

23. A detector as claimed in claim 22 wherein said metal atoms are transition metal atoms.

24. A detector as claimed in claim 23 wherein said transition metal atoms are taken from the group consisting essentially of Group VIII elements of the periodic table, copper and zinc as well as metals of the lanthanide and actinide series.

25. A detector as claimed in claim 2 wherein said material contains metal atoms as an active element therein, wherein said deterioration is reduction of the metal atoms and wherein said charge carriers are holes.

26. A detector as claimed in claim 25 wherein said metal atoms are transition metal atoms.

27. A detector as claimed in claim 26 wherein said transition metal atoms are taken from the group consisting essentially of Group VIII elements of the periodic table, copper and zinc as well as metals of the lanthanide and actinide series.

28. A detector as claimed in claim 2 in which said material comprises a binding material.

29. A detector as claimed in claim 28 wherein said binding material is taken from the group consisting essentially of gelatin, agar, ion exchange resins, acrylimide gel, styrenes, starches, glasses, clays, methacrylates, nylons, magnetite, nickel oxides and other polymers.

30. A detector as claimed in claim 2 wherein said material includes an anti-dessicant substance to prevent drying.

31. A detector as claimed in claim 30 wherein said anti-dessicant substance is taken from the group consisting essentially of glycerin, dimethyl sulfoxide, trimethylamine, and ethylene glycol.

32. A detector as claimed in claim 2 wherein said material contains trace amounts of antibiotics to prevent destruction of said material from microbial growth.

33. A detector as claimed in claim 32 wherein said antibiotics are taken from the group consisting essentially of amphotericin B, streptomycin, penicillin, mercurials, and their congeners.

34. A detector as claimed in claim 2 wherein the molecular species detected comprises small molecule of molecular weight of about one hundred Daltons or less and wherein said material reversibly binds to said small molecules.

35. A detector as claimed in claim 34 wherein the molecular species is taken from the group consisting essentially of O₂, CO₂, CN, NO, NO₂, SO₂, OH^-, H₂ S, H₂, HCl, D₂, and F^-, and wherein said material reversibly binds to at least one member of the group.

36. A detector as claimed in claim 34 wherein the molecular species is O₂ and in which said material contains an oxyemphore.

37. A detector as claimed in claim 36 wherein said oxyemphore is taken from the group consisting essentially of iron-containing emphores, copper-containing emphores, nickel-containing emphores, cobalt-containing emphores, iridium-containing emphores, platinum-containing emphores and manganese-containing emphores.

38. A detector as claimed in claim 34 wherein the molecular species is CO and in which said material contains a CO-binding material.

39. A detector as claimed in claim 38 wherein said CO-binding material is taken from the group consisting essentially of hemoglobin, iron dimethyl glyoxime, and iridium cis-1, 2-bis ethylene.

40. A detector as claimed in claim 34 wherein the molecular species is taken from the group consisting essentially of SO₂, HCl, H₂ and D₂ and wherein said material contains an emphore taken from the group consisting essentially of iridium chlorocarbonyl bis-triphenyl phosphine, and iridium cis-1, 2-bis-disphenyl phosphine ethylene and their congeners.

41. A detector as claimed in claim 34 wherein the molecular species is cyanide and wherein said material contains an emphore taken from the group consisting essentially of hemoglobin and iron dimethyl glyoxime.

42. A detector as claimed in claim 34 wherein the molecular species is taken from the group consisting essentially of NO, NO₂, F^- and OH^-, and wherein said material includes hemoglobin.

43. A detector to sense the presence and amount of a molecular species of interest in the environment about the detector, that comprises, in combination:

a material whose optical density changes at a single wavelength when the material is exposed to the molecular species of interest as a consequence of reversible binding, that is, the optical density of the material changes as a function of the partial pressure of the species of interest in the vicinity of the detector; and

optical means for sensing the change in optical density at said single wavelength and adapted to relate said change to the partial pressure of said species in the vicinity of said material at each level of partial pressure as a continuous function of said partial pressure, said optical means comprising means to introduce light at said single wavelength to pass through said material and means to detect the light after it has passed through the material.

44. A detector as claimed in claim 43 that is operable to selectively sense the presence and amount of a plurality of species of interest and in which the optical means comprises a plurality of sources of light each providing light at a single frequency and a plurality of radiation detectors, a radiation detector being associated with each light source and positioned to receive the light from its associated light source after it has passed through said material and to provide a signal indicative of the presence and amount of one species of interest.

45. A detector as claimed in claim 43 wherein the optical means comprises a source of light and a radiation sensor whose output bears a relationship to the intensity of the radiation received thereby, said source of light, said material, and said radiation sensor forming a unitary structure wherein the three elements just named bear a fixed mechanical relationship to one another in order that the radiation sensor provide an output whose magnitude is directly related to and is a continuous function of said optical density.

46. A detector as claimed in claim 45 that includes electrical circuitry connected to receive the output of the radiation sensor and operable to relate said output to the partial pressure of the molecular species of interest.

47. A detector as claimed in claim 45 in which said material is subjected to an aging process whereby the opacity of the material increases as a function of time and which affects the accuracy of the detecting function, in which said detector further includes means to reset said material by the injection of charge carriers, which charge carriers enter said material and reverse the aging thereof, which means to reset comprises electric means that serves as a source of charge carriers that are injected into the material, an electroactive mediator coextensive with said material and a source of light, the electroactive mediator and light from the source of light acting to facilitate in situ charge carrier injection into the material.

48. A detector for sensing the presence of a molecular species of interest in the environment about the detector, that comprises, in combination:

a sensing material of which at least one detectable property thereof changes when the sensing material is subjected to the molecular species of interest as a consequence of reversible binding of the species of interest to the sensing material, the change in the detectable property being in the bulk of the sensing material and having a short time constant τ

_c, the change being reversible in that the sensing material reverts to the original state when the molecular species of interest is removed, said sensing material being further subject to bulk deterioration which is a long term effect, having a time constant τ

_o, which has an adverse effect on the accuracy of the detector, wherein τ

_o >

>

τ

_c ;

means to pass an electric current through the sensing material for introducing charge carriers into the sensing material to reverse said deterioration in the bulk thereof and return the sensing material to its original state;

an electroactive mediator co-extensive with said sensing material to form a composite material; and

means to introduce electromagnetic radiation to the composite material to facilitate the introduction of said charge carriers into the sensing material.

49. A detector as claimed in claim 48 wherein deterioration is oxidation of said sensing material, wherein the reversal of the deterioration effect is a reduction process in which the charge carriers are electrons, and wherein the time constant τ

_R to return the sensing material to its original state is found in the expression

space="preserve" listing-type="equation">τ

.sub.R = 9.7·

10.sup.10 ([Σ

]/κ

) ·

(1/η

.sub.R)

wherein Σ

is the molar sum of all the oxidized constituents in said material, κ

is the electric current through the sensing material in microamperes and η

_R is the efficiency of reduction process.

50. A detector for sensing a molecular species of interest, that comprises, in combination:

sensing material having a property that changes when the sensing material is exposed to said molecular species as a consequence of reversible binding of said molecular species to the material, that is, there is no net chemical effect upon either said sensing material or said molecular species which is bound thereto as a consequence of said reversible binding, said sensing material being further subject to deterioration which adversely affects its detecting function, said deterioration being a net chemical effect;

sensing means operable to note a bulk change in said property and operable to relate the bulk change to the presence of the molecule of interest;

an electroactive mediator co-extensive with the sensing material; and

reset means operable to introduce charge carriers into the bulk of the sensing material, which charge carriers enter the energy states of the sensing material and counteract said deterioration by reversing said net chemical effect, said reset means comprising a source of such charge carriers and means to irradiate the sensing material and the electroactive mediator, the combined effect of the electroactive mediator and radiation from the means to irradiate being to facilitate introduction of charge carriers to the energy states of the sensing material.

51. A method of detecting the presence and the amount of a specific molecular species, that comprises:

exposing a material to a fluid containing the molecular species of interest, said material being one whose properties change when the material is exposed to the species by virtue of reversible binding of the molecules of the species said material being a composite that includes a sensing material and an electroactive mediator, said material being one that is subject to deterioration;

sensing the magnitude of the change in the properties as a consequence of said reversible binding to sense the presence of the molecular species and the partial pressure thereof in the fluid;

directing radiation upon the composite material; and

introducing charge carriers to said sensing material to counteract any unwanted deterioration that occurs therein, said electroactive mediator and said radiation acting to facilitate the introduction of charge carriers to the sensing material.

52. In a process wherein a chemical change is wrought upon a material as a consequence of it having been subjected to a reaction or reactions, the further steps of injecting appropriate charge carriers into the material to counteract unwanted deterioration thereof and cause the material to revert to a desired state, adding small amounts of an electroactive mediator to the material to facilitate charge carrier transfer thereto, the resulting material being a matrix material and the electroactive mediator, said electroactive mediator being taken from the group consisting essentially of dyes, quinones, free transition metals and other molecules with conjugated π

-electron systems as well as other elements and complexes with d^- and f^- electrons capable of moving between two or more electronic states, introducing photons to the resulting material, the electroactive mediator being one which permits, in the presence of said photons, charge carrier transfer to the resulting material at an applied electric potential difference that is below the electrolysis potential of the resulting material, said matrix material containing an emphore that detects the presence of a molecular species by reversibly binding to the species and is changed in properties in the process of such reversible binding.

53. A method of controlling a biological or a chemical process of a material that comprises introducing an electroactive mediator to the bulk of the material, directing radiation into the bulk of the material and introducing charge carriers to the bulk of the material and into the energy states thereof, the combined effects of the electroactive mediator and radiation being to facilitate introduction of charge carriers to the energy states of the material.