US4444644A
Expired / Lapsed
US
⏱️ 0.0 years remaining
PH Electrode
Assignee: Sumitomo Electric Industries Ltd
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Filing: 1982-02-16
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Granted: 1984-04-24
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Expires: 2002-02-16
Abstract
Abstract A PH electrode is provided with an ISFET for generating a potential difference according to the PH value of an electrolyte to be measured, and includes a cell for driving the ISFET, so that the PH electrode can be used, as it is, with a conventional, potential difference type PH meter.
Inventors
- 👤 Junichi Hiramoto
- 👤 Shinichi Ohkawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 03:38
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/26; G01N27/403; G01N27/414; G01N27/4148
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
151 words
A PH detecting apparatus, comprising; an electrode including an ion-sensitive field-effect transistor (ISFET) for providing a potential difference according to a PH value of an electrolyte solution under measurement, said electrode including an operating DC source connected to the source of said ISFET, said electrode further comprising, a circuit comprising an operational amplifier in parallel with said DC source, a resistor connected in series to one side of said DC source, said ISFET connected in series to the other side of said DC source, and a transistor having its emitter connected to said resistor, its base connected to said amplifier and its collector connected to said ISFET, an output being taken from the junction of a collector of said transistor and a drain of said ISFET, said electrode forming one input to a potential difference type PH apparatus, and a reference electrode forming a second input to said potential difference apparatus.
Claim 2
Dependent Claim
151 words
A PH detecting apparatus, comprising; an electrode including an ion-sensitive field-effect transistor (ISFET) for providing a potential difference according to a PH value of an electrolyte solution under measurement, said electrode including an operating DC source connected to the source of said ISFET, said electrode further comprising, a circuit comprising an operational amplifier in parallel with said DC source, a resistor connected in series to one side of said DC source, said ISFET connected in series to the other side of said DC source, and a transistor having its emitter connected to said resistor, its base connected to said amplifier and its collector connected to said ISFET, an output being taken from the junction of a collector of said transistor and a drain of said ISFET, said electrode forming one input to a potential difference type PH apparatus, and a reference electrode forming a second input to said potential difference apparatus.
Claim 3
Dependent Claim
45 words
A device as claimed in claim 1, comprising said ISFET positioned at the end of a probe and a housing attached to said probe for said DC source, and said ISFET connected to said DC source and said collector of said transistor through lead wires.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-04-24 | 1987-10-24 | 1988-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-04-24 | 1991-10-24 | 1992-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-04-24 | 1995-10-24 | 1996-04-24 | $7700.00 | Window Closed / Lapsed |