Electricity: measuring and testing – Electrolyte properties – Using a ph determining device
Patent
1984-08-17
1987-09-01
Eisenzopf, Reinhard J.
Electricity: measuring and testing
Electrolyte properties
Using a ph determining device
324715, 324441, 204406, 204416, G01N 2726
Patent
active
046911677
ABSTRACT:
The apparatus (10) for determining the activity of an ion (pIon) in a liquid (16) comprises a measuring circuit (10) including an ion sensitive field effect transistor (ISFET 12), a reference electrode (32) adjacent the ISFET (12), a temperature sensor (34) adjacent the ISFET (12), amplifiers (22 and 38) coupled to the ISFET (12) and temperature sensor (34), and control, computing and memory circuits (30, 44, and 46) coupled to the amplifiers and operable to maintain two of the following three parameters, V.sub.gs (gate-source potential), V.sub.ds (drain-source potential) and I.sub.D (drain-source current) at a constant value so that the third parameter can be used for determining the ion activity or pIon. The pIon sensitivity of the apparatus (10), as a function of temperature and/or the variation of the drain-source current, I.sub.D, as a function of the temperature are controlled by controlling the V.sub.gs so that the pIon can be calculated from a formula stored in the memory (46 ).
REFERENCES:
patent: 4267504 (1981-05-01), Bergveld
patent: 4302299 (1981-11-01), Ishikawa
patent: 4385274 (1983-05-01), Shimada
Electrochemistry of Chemically Sensitive FET's Janata Sensors and Actuators, vol. 4-1983.
P. Bergveld and N. F. de Rooij, "The History of Chemically Sensitive Semiconductor Devices", Sensors and Actuators, (1981), pp. 5-16, printed by Elsevier Sequoia S. A. Lausanne, the Netherlands.
de Rooy Nicolaas F.
v.d. Vlekkert Hendrik H.
Collins Henry W.
Eisenzopf Reinhard J.
Harvey Jack B.
Sentron v.o.f.
Vigil Thomas R.
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