Method of forming a permselective layer

• US 5,212,050 A
• Filed: 08/15/1990
• Issued: 05/18/1993
• Est. Priority Date: 11/14/1988
• Status: Expired due to Term

• Current Assignee: i STAT Corporation (Abbott Laboratories)
• Original Assignee: i STAT Corporation (Abbott Laboratories)
• Inventors: Davis, Graham, Lauks, Imants R., Mier, Randall M., Piznik, Sylvia
• Primary Examiner(s): McCamish, Marion E.
• Assistant Examiner(s): RoDee, Christopher D.
• Application Number:
  US07/568,441
• Time in Patent Office: 1,007 Days
• Field of Search: 430/320, 430/325, 430/326, 430/328, 430/330, 430/304, 430/313, 430/644, 430/311, 435/288
• US Class Current: 430/320
• CPC Class Codes: B01L 2200/12 Specific details about manufacturing devices
• CPC Class Codes: B01L 2300/0636 Integrated biosensor, microarrays
• CPC Class Codes: B01L 2300/0645 Electrodes
• CPC Class Codes: B01L 2300/0877 Flow chambers
• CPC Class Codes: B01L 3/0268 using pulse dispensing or spraying, eg. inkjet type, piezo actuated ejection of droplets from capillaries
• CPC Class Codes: B01L 3/502707 characterised by the manufacture of the container or its components by shaping or joining plastic parts B29C59/00, B29C65/00; by laminating B32B37/00; manufacture of microstructural devices in general B81C
• CPC Class Codes: B01L 3/5088 confining liquids at a location by surface tension, e.g. virtual wells on plates, wires B01L3/50857 takes precedence
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: G01N 2035/00059 vacuum chucks
• CPC Class Codes: G01N 2035/00237 Handling microquantities of analyte, e.g. microvalves, capillary networks
• CPC Class Codes: G01N 2035/00455 Controlling humidity in analyser
• CPC Class Codes: G01N 2035/00534 Mixing by a special element, e.g. stirrer
• CPC Class Codes: G01N 2035/1034 Transferring microquantities of liquid
• CPC Class Codes: G01N 2035/1076 plurality or independently movable heads
• CPC Class Codes: G01N 33/5438 Electrodes
• CPC Class Codes: G01N 35/0099 comprising robots or similar manipulators robots per se B25J
• CPC Class Codes: G01N 35/109 with two horizontal degrees of freedom

Abstract

A method of forming a permselective layer on preselected areas of a substantially planar sensing device is disclosed. The claimed method includes establishing and confining a liquid film, derived from a silane compound mixed in a suitable solvent, within a predetermined area of the sensing device. The process relates to photolithographic imaging and developing methods coupled to a film-curing step that provides a patterned permselective layer having the desired semipermeable characteristics.

Claims

1. A method for forming a permselective layer on preselected areas of a substantially planar sensing device which comprises:

(a) establishing a photoresist layer on a substantially planar sensing device;

(b) processing said photoresist layer using photolithographic techniques to expose preselected areas of said sensing device;

(c) establishing at least one film comprising a silane compound mixed with a suitable solvent on the sensing device of step (b), said compound having the formula R'"'"'_n Si(OR)_4-n, in which n is an integer selected from the group consisting of 0, 1, and 2;

R'"'"' is a hydrocarbon radical comprising 3-12 carbon atoms; and

R is a hydrogen radical or a lower alkyl radical comprising 1-4 carbon atoms; and

(d) heating said film to a temperature of at least about 100°

C. for a period of time effective to form a permselective layer having a thickness of about 1 to about 1000 nm sufficient to provide said permselective layer with the desired semipermeable properties in which molecules having about a first preselected molecular weight or above are substantially precluded from permeating through said permselective layer, while molecules having about a second preselected molecular weight or below may effectively permeate therethrough; and

(e) removing the underlying photoresist layer and the permselective layer overlaid thereover from all except the preselected areas of said sensing device.

2. The method of claim 1 which further comprises heating said device of step (e) to a temperature in excess of about 150°

C. to about 250°

C. to maximize the indicator electrode response toward the oxidation of hydrogen peroxide.

3. The method of claim 1 which further comprises heating said device of step (e) to a temperature in the range of about 150°

C. to about 250°

to maximize the indicator electrode response toward the oxidation of hydrogen peroxide.

4. The method of claim 1 in which said film is heated in step (d) to a temperature or about 160°

C. to maximize the indicator electrode response toward the oxidation of hydrogen peroxide.

11. The method of claim 1 or 5 in which the thickness of said permselective layer is such that said permselective layer is permeable to molecules having a molecular weight of about 50 or less, yet substantially impermeable to molecules having a molecular weight of about 120 or more.

12. The method of claim 1 or 5 in which the thickness of said permselective layer is in the range of about 20 to about 500 Å

.

13. The method of claim 1 or 5 in which said permselective layer is further characterized as:

(i) having a thickness in the range of about 50 to about 100 Å

;

(ii) being permeable to molecules selected from the group consisting of dioxygen and hydrogen peroxide; and

(iii) being substantially impermeable to molecules selected from the group consisting of uric acid, ascorbic acid, salicylic acid, 2-(p-isobutylphenyl)propionic acid, cysteine, 4-acetamidophenol, and physiological salts thereof.

14. The method of claim 1 or 5 in which said sensing device is an amperometric electrochemical sensor.

15. The method of claim 1 or 5 in which said solvent is comprised of an aqueous solution of a nonionic surfactant present in a concentration of about 0.005 to about 0.2 percent by weight of said aqueous solution.

16. The method of claim 1 or 5 in which said solvent is a water-immiscible organic solvent.

17. The method of claim 1 or 5 in which said solvent is a chlorinated organic solvent selected from the group consisting of methylene chloride, trichloroethane, tetrachloroethane, chlorobenzene, dichlorobenzene, and mixtures thereof.

18. The method of claim 1 or 5 in which said film is established by a means selected from the group consisting of spin-coating, dip-coating, spray-coating, and microdispensing.

19. The method of claim 1 or 5 in which said film is heated to a temperature in the range of about 100°

C. and about 250°

C. for a period of at least about 5 minutes.

20. The method of claim 1 or 5 in which said silane compound is N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

21. The method of claim 1 or 5 in which said film is established by a microdispensing system.

22. The method of claim 1 or 5 in which different silane films are established.

23. The method of claim 1 or 5 in which said preselected areas encompass the indicator electrode of an amperometric electrochemical sensor.

24. The method of claim 1 or 5 in which said photoresist layer is comprised of a positive photoresist and said processing step comprises (i) irradiating said photoresist layer through a mask, and (ii) developing the irradiated photoresist layer to expose preselected areas of said sensing device.

25. The method of claim 24 in which said developing step comprises contacting said irradiated photoresist layer with a lower alkyl acetate ester solvent.

26. The method of claim 1 or 5 in which step (e) or step (f), respectively, comprises exposing said device to a solvent capable of dislodging or dissolving said photoresist layer.

27. The method of claim 1 or 5 in which said hydrocarbon radical further comprises at least one heteroatom selected from the group consisting of oxygen, nitrogen, phosphorus, sulfur and stable combinations thereof.

28. The method of claim 1 or 5 in which n is equal to 1.

39. The method of claim 21 or 32 in which said solid film is further characterized as:

(i) having a thickness in the range of about 50 to about 100 Å

;

(ii) being permeable to molecules selected from the group consisting of dioxygen and hydrogen peroxide; and

(iii) being substantially impermeable to molecules selected from the group consisting of uric acid, ascorbic acid, salicylic acid, 2-(p-isobutylphenyl)proprionic acid, cysteine, 4-acetamidophenol, and physiological salts thereof.

47. The method of claim 1, 5, 29 or 32 in which the thickness of said permselective layer is in the range of about 20 to about 200 Å

.

48. The method of claim 1, 5, 29 or 32 in which the thickness of said permselective layer is in the range of about 50 to about 100 Å

.

5. A method of forming a permselective layer on preselected areas of a substantially planar sensing device which comprises:

(a) establishing at least one film comprising a silane compound mixed with a suitable solvent on a substantially planar sensing device, said compound having the formula R'"'"'_n Si(OR)_4-n, in which n is an integer selected from the group consisting of 0, 1 and 2;

R'"'"' is a hydrocarbon radical comprising 3-12 carbon atoms; and

R is a hydrogen radical or a lower alkyl radical comprising 1-4 carbon atoms; and

(b) heating said film to a temperature of at least about 100°

C. for a period of time effective to form a permselective layer having a thickness of about 1 to about 1,000 nm sufficient to provide said permselective layer with the desired semipermeable properties in which molecules having about a first preselected molecular weight or above are substantially precluded from permeating through said permselective layer, while molecules having about a second preselected molecular weight or below may effectively permeate therethrough;

(c) establishing a photoresist layer on said permselective layer;

(d) processing said photoresist layer using photolithographic techniques such that a proportion of the underlying permselective layer becomes exposed and subject to further processing, while those preselected areas of the device retain a protective cap of photoresist material;

(e) removing said exposed permselective layer; and

(f) removing said protective photoresist layer to leave a permselective layer over preselected areas of said device.

6. The method of claim 5 in which step (e) comprises contacting said permselective layer with an etchant selected from the group consisting of dry agents, wet agents, and combinations thereof.

7. The method of claim 5 in which step (e) comprises contacting said permselective layer with an etchant selected from the group consisting of an oxygen plasma, a 0.0001-0.01 weight percent solution of hydrofluoric acid in a protic solvent and combinations thereof.

8. The method of claim 5 which further comprises heating said device of step (f) to a temperature in excess of about 150°

C. to about 250°

C. to maximize the indicator electrode response toward the oxidation of hydrogen peroxide.

9. The method of claim 5 which further comprises heating said device of step (f) to a temperature in the range of about 150°

C. to about 250°

C. to maximize the indicator electrode response toward the oxidation of hydrogen peroxide.

10. The method of claim 5 in which said film is heated in step (b) to a temperature of about 160°

C. to maximize the indicator electrode response toward the oxidation of hydrogen peroxide.

29. A method for forming a patterned semipermeable solid film onto a planar sensing device which comprises:

(a) establishing a layer of a resist material over a planar sensing device;

(b) subjecting the layer of step (a) to radiant energy through a photolithographic mask and developing the resultant irradiated layer such that preselected area of said device become exposed and subject to further processing;

(c) establishing a liquid film over the patterned layer of step (b), which liquid film comprises an organosilicon compound mixed with a suitable solvent, said compound having the formula R'"'"'Si(OR)₃ in which R'"'"' is a hydrocarbon radical comprising 3-12 carbon atoms and R is a lower alkyl radical comprising 1-4 carbon atoms;

(d) heating the liquid film of step (c) to a temperature of at least about 100°

C. for a period of time effective to form a solid film having a thickness of about 20 to about 500 Å

sufficient to provide said solid film with the desired semipermeable properties in which molecules having molecular weights above a given threshold can be effectively excluded from entering and diffusing through said solid film, while allowing the free passage and diffusion of lower molecular weight electroactive species; and

(e) exposing the solid film of step (d) to a solvent capable of dislodging the underlying layer of resist material and allowing said solid film to separate from said device, leaving a patterned semipermeable solid film over the preselected areas of said device.

30. The method of claim 29 which further comprises heating said device of step (e) to a temperature in the range of about 150°

to about 250°

C. to maximize the indicator electrode response toward the oxidation of hydrogen peroxide.

31. The method of claim 29 in which said film is heated in step (d) to a temperature of 170°

C. to maximize the indicator electrode response toward the oxidation of hydrogen peroxide.

37. The method of claim 29 or 32 in which the thickness of said solid film is such that molecules having a molecular weight of about 120 or more are substantially precluded from permeating through said solid film, while molecules having a molecular weight of about 50 or less may diffuse through effectively.

38. The method of claim 29 or 32 in which the thickness of said solid film is in the range of about 20 to about 500 Å

.

40. The method of claim 29 or 32 in which said planar sensing device is an amperometric electrochemical sensor manufactured by thin film technology.

41. The method of claim 29 or 32 in which said solvent is comprised of an aqueous solution of a nonionic surfactant present in a concentration of about 0.005 to about 0.2 percent by weight of said aqueous solution.

42. The method of claim 29 or 32 in which said solvent is a water-immiscible organic solvent.

43. The method of claim 29 or 32 in which said liquid film is established on said planar sensing device by a means selected from the group consisting of spin-coating, dip-coating, spray-coating, and microdispensing.

44. The method of claim 29 or 32 in which said liquid is heated to a temperature in the range of about 100°

C. to about 250°

C. for a period of at least about 5 minutes.

45. The method of claim 29 or 32 in which said hydrocarbon radical further comprises at least one heteroatom selected from the group consisting of oxygen, nitrogen, phosphorus, sulfur, and stable combinations thereof.

46. The method of claim 29 or 32 in which said organosilicon compound is N-)2-aminoethyl)-3-aminopropyltrimethoxysilane.

32. A method of forming a patterned semipermeable solid film onto a planar sensing device which comprises:

(a) establishing a liquid film over a planar sensing device, which liquid film comprises an organosilicon compound mixed with a suitable solvent, said compound having the formula R'"'"'Si(OR)₃ in which R'"'"' is a hydrocarbon radical comprising 3-12 carbon atoms and R is a lower alkyl radical comprising 1-4 carbon atoms;

(b) heating the liquid film of step (a) to a temperature of at least about 100°

C. for a period of time effective to form a solid film having a thickness of about 20 to about 500 Å

sufficient to provide said solid form with the desired semipermeable properties in which molecules having molecular weights above a given threshold can be effectively excluded from entering and diffusing through said solid film, while allowing the free passage and diffusion of lower molecular weight electroactive species;

(c) establishing a layer of a resist material over the solid film of step (b);

(d) subjecting the layer of step (c) to radiant energy through a photolithographic mask and developing the resultant irradiated layer such that a substantial proportion of the underlying solid film becomes exposed and subject to further processing, while those preselected areas of the device retain a protective cap of resist material;

(e) subjecting the exposed solid film of step (d) to an etchant for a length of time sufficient to remove substantially all of said exposed solid film; and

semipermeable solid film over the preselected areas of said device.

33. The method of claim 32 in which said etchant is selected from the group consisting of dry and wet agents.

34. The method of claim 32 in which said etchant is selected from the group consisting of an oxygen plasma and a 0.0001-0.01 weight percent solution of hydrofluoric acid in a protic solvent.

35. The method of claim 32 which further comprises heating said device of step (f) to a temperature in the range of about 150°

C. to about 250°

C. to maximize the indicator electrode response toward the oxidation of hydrogen peroxide.

36. The method of claim 32 in which said film is heated in step (b) to a temperature of 170°

C. to maximize the indicator electrode response toward the oxidation of hydrogen peroxide.