US4801655A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fiber optic pH sensor having low drift rate
Assignee: Becton Dickinson Critical Care Systems Pte Ltd
•
Filing: 1987-08-20
•
Granted: 1989-01-31
•
Expires: 2007-08-20
Abstract
Abstract A hydrolyzed dye/gel polymer for use in a pH-based sensor is characterized by its chemical and optical stability with respect to dye loss with time. Preferably, the dye/gel polymer is hydrolyzed by heating in a dilute base solution for a period of time sufficient to remove weakly bonded dye molecules from the polymer, then washed to remove the base solution and loose dye.
Inventors
- 👤 Richard C. Murray, Jr.
- 👤 Mark S. Goorsky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:49
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/75; G01N21/77; G01N21/7703; G01N21/78; G01N21/80
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
127 words
A method of treating a chemically and optically unstable hydrophilic acrylic dye/gel polymer which when used as a pH sensor exhibits a drift rate of about 0.03 pH unit or more over a 10 to 15 hour period to convert said unstable polymer to one having its chemical and optical stability with respect to dye loss with time increased to a point at which said polymer exhibits substantially reduced pH drift when used as a pH sensor, said method comprising: (1) treating said unstable polymer with an aqueous solution of a base, (2) washing the base-treated polymer with water to remove substantially all the base, and (3) contacting the washing polymer with an anhydrous solvent having a high affinity for water to remove water from said polymer.
Claim 2
Independent Claim
127 words
A method of treating a chemically and optically unstable hydrophilic acrylic dye/gel polymer which when used as a pH sensor exhibits a drift rate of about 0.03 pH unit or more over a 10 to 15 hour period to convert said unstable polymer to one having its chemical and optical stability with respect to dye loss with time increased to a point at which said polymer exhibits substantially reduced pH drift when used as a pH sensor, said method comprising: (1) treating said unstable polymer with an aqueous solution of a base, (2) washing the base-treated polymer with water to remove substantially all the base, and (3) contacting the washing polymer with an anhydrous solvent having a high affinity for water to remove water from said polymer.
Claim 3
Dependent Claim
32 words
A method as recited in claim 1 in which said unstable hydrophilic acrylic dye/gel polymer's pH drift over a 16 hour period is reduced by at least about one order of magnitude.
Claim 4
Dependent Claim
31 words
A method as recited in claim 1 in which said unstable hydrophilic acrylic dye/gel polymer's pH drift over a 16 hour period is reduced to less than about 0.005 pH unit.
Claim 5
Dependent Claim
19 words
A method as recited in claim 3 in which said unstable hydrophilic acrylic dye/gel polymer comprises a polyacrylamide polymer.
Claim 6
Dependent Claim
14 words
A method as recited in claim 4 in which said dye is phenol red.
Claim 7
Independent Claim
18 words
A method as recited in any one of claims 1-5, inclusive, in which said base is sodium hydroxide.
Claim 8
Dependent Claim
15 words
A method as recited in claim 6 in which said anhydrous solvent is anhydrous ethanol.
Claim 9
Independent Claim
131 words
A method of treating a chemically and optically unstable polyacrylamide/phenol red dye/gel polymer which when used as a pH sensor exhibits a drift rate of about 0.03 pH unit or more over a 10 to 15 hour period to convert said unstable polymer to one having its chemical and optical stability with respect to dye loss with time increased to a point at which said polymer exhibits a pH drift over a 16 hour period of less than about 0.005 pH unit when used as a pH sensor, said method comprising: (1) treating said unstable polymer with an aqueous sodium hydroxide solution, (2) washing the thus-treated polymer with water to remove substantially all the sodium hydroxide, and (3) contacting the washed polymer with anhydrous ethanol to remove water from said polymer.
Claim 10
Independent Claim
131 words
A method of treating a chemically and optically unstable polyacrylamide/phenol red dye/gel polymer which when used as a pH sensor exhibits a drift rate of about 0.03 pH unit or more over a 10 to 15 hour period to convert said unstable polymer to one having its chemical and optical stability with respect to dye loss with time increased to a point at which said polymer exhibits a pH drift over a 16 hour period of less than about 0.005 pH unit when used as a pH sensor, said method comprising: (1) treating said unstable polymer with an aqueous sodium hydroxide solution, (2) washing the thus-treated polymer with water to remove substantially all the sodium hydroxide, and (3) contacting the washed polymer with anhydrous ethanol to remove water from said polymer.
Claim 11
Dependent Claim
16 words
A chemically and optically stable hydrophilic acrylic dye/gel polymer produced by the method of claim 1.
Claim 12
Dependent Claim
17 words
A chemically and optically stable hydrophilic polyacrylamide/phenol red dye/gel polymer produced by the method of claim 8.
References Cited (Backward Citations)
US3984204A
Cited
US4166804A
Cited
US4194877A
Cited
US4200110A
Cited
US4378971A
Cited
US4466941A
Cited
US4476870A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-01-31 | 1992-08-01 | 1993-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-31 | 1996-08-01 | 1997-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-31 | 2000-08-01 | 2001-01-31 | $7700.00 | Window Closed / Lapsed |