US4940945A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Interface circuit for use in a portable blood chemistry measuring apparatus
Assignee: BIOLOGIX Inc 1121 L STREET SUITE 1000 SACRAMENTO CA 95814
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Filing: 1987-11-02
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Granted: 1990-07-10
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Expires: 2007-11-02
Abstract
Abstract An interface circuit for use in a portable apparatus for measuring the electrochemical characteristics of a sample is disclosed. A disposable cartridge, including a plurality of interconnected flow chambers, houses a printed circuit board substrate upon which reference and indicating electrodes are formed. The electrodes are employed in the presence of chemical reagents to aid in the electrochemical determination of a sample undergoing analysis. Such a system provides a high source impedance signal. Interface circuitry is provided between the electrodes and measuring electronics which causes a controllable current loop to be formed through the physical contacts points between the electrodes and the measuring electronics so that low ohmic contact is established. The control circuitry for the current loop is isolated from the measuring circuitry so that measurements taken are not influenced by the current loop formation.
Inventors
- 👤 Douglas J. Littlejohn
- 👤 Richard L. Fellows
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:53
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/48; G01N33/483; G01N33/487; G01N33/49; G01N33/4925
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
184 words
An apparatus for measuring a signal having a high source impedance of the type in which the signal to be measured is presented across a pair of contacts, and a measuring circuit is placed in physical contact with the pair of contacts, comprising interface means having a plurality of contacting structures which can be placed in physical contact with and at spaced apart points on at least a first one of the pair of contacts for circulating a current through the first one of the pair of contacts by way of the plurality of contacting structures, wherein the circulating current flows out of one of the plurality of contacting structures, through the first one of the pair of contacts, and into another of the plurality of contacting structures, and further wherein the magnitude of the circulated circuit is selected to cause a low ohmic contact to be developed between the plurality of contacting structures and the first one of the pair of contacts; means for measuring the signal between one of the plurality of contacting structures and the other of the pair of contacts.
Claim 2
Independent Claim
184 words
An apparatus for measuring a signal having a high source impedance of the type in which the signal to be measured is presented across a pair of contacts, and a measuring circuit is placed in physical contact with the pair of contacts, comprising interface means having a plurality of contacting structures which can be placed in physical contact with and at spaced apart points on at least a first one of the pair of contacts for circulating a current through the first one of the pair of contacts by way of the plurality of contacting structures, wherein the circulating current flows out of one of the plurality of contacting structures, through the first one of the pair of contacts, and into another of the plurality of contacting structures, and further wherein the magnitude of the circulated circuit is selected to cause a low ohmic contact to be developed between the plurality of contacting structures and the first one of the pair of contacts; means for measuring the signal between one of the plurality of contacting structures and the other of the pair of contacts.
Claim 3
Dependent Claim
70 words
The apparatus of claim 1, wherein the interface means comprises phototransistor means having as collector coupled to at least one of the contacting structures and an emitter coupled to at least a different one of the contacting structures for generating the current to be circulated; and means in optical communication with the phototransistor for driving the phototransistor means so that the driving means are electrically isolated from the phototransistor means.
Claim 4
Dependent Claim
49 words
The apparatus of claim 1, wherein the measuring means includes means having a high impedance input coupled to one of the contacting structures for electronically buffering and amplifying the high impedance signal appearing across the pair of contacts with respect to the other one of the pair of contacts.
Claim 5
Dependent Claim
47 words
The apparatus of claim 2, wherein the phototransistor means has a base, and further wherein the driving means includes a light emitting diode optically coupled to the base of the phototransistor means; and means coupled to the light emitting diode for driving the light emitting diode means.
Claim 6
Independent Claim
147 words
An apparatus for measuring a high impedance signal which is presented across a pair of contacts, comprising a phototransistor having a base, a collector which can be placed in physical contact with one of the pair of contacts, and an emitter which can be placed in physical contact with the one of the pair of contacts at a point spaced apart from the collector; a light source in optical communication with the base of the phototransistor which is operable to drive the phototransistor at a circulating current level that is sufficient to cause microwelds to be developed at the points of physical contact between the collector and emitter and the one of the pair of contacts, so that a low ohmic path is provided therebetween; and means for measuring the signal between one of the pair of contacts and either the collector or emitter of the phototransistor.
Claim 7
Independent Claim
147 words
An apparatus for measuring a high impedance signal which is presented across a pair of contacts, comprising a phototransistor having a base, a collector which can be placed in physical contact with one of the pair of contacts, and an emitter which can be placed in physical contact with the one of the pair of contacts at a point spaced apart from the collector; a light source in optical communication with the base of the phototransistor which is operable to drive the phototransistor at a circulating current level that is sufficient to cause microwelds to be developed at the points of physical contact between the collector and emitter and the one of the pair of contacts, so that a low ohmic path is provided therebetween; and means for measuring the signal between one of the pair of contacts and either the collector or emitter of the phototransistor.
References Cited (Backward Citations)
US2998371A
Cited
US3467582A
Cited
US3556950A
Cited
US3638109A
Cited
US3648159A
Cited
US3658478A
Cited
US3742594A
Cited
US3968774A
Cited
US3926766A
Cited
US4180771A
Cited
US4324256A
Cited
US4214968A
Cited
US4293307A
Cited
US4342964A
Cited
US4272245A
Cited
US4225410A
Cited
US4338175A
Cited
US4401547A
Cited
US4290015A
Cited
US4340457A
Cited
US4312734A
Cited
US4452682A
Cited
US4528500A
Cited
US4397725A
Cited
US4336121A
Cited
US4436610A
Cited
US4545382A
Cited
US4589418A
Cited
US4454007A
Cited
US4536274A
Cited
US4685465A
Cited
US4801546A
Cited
US4642560A
Cited
US4707657A
Cited
US4561963A
Cited
EP0185941A2
Cited
US4721601A
Cited
US4645572A
Cited
US4615340A
Cited
US4662996A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-09 | 1994-01-08 | 1994-07-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-09 | 1998-01-08 | 1998-07-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-09 | 2002-01-08 | 2002-07-10 | $7700.00 | Window Closed / Lapsed |