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US 2013/0085701 A1Published application
Self-Calibrating Ion Meter
AssigneeSentient Technologies, Inc.
InventorsMark Bain, Frederick Quincy Johnson
Life of this patent
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Abstract
An ion meter is calibrated by providing two ISFETS with different areas, where the two gate areas are used to calibrate the two ISFETS with respect to one another. The use of two ISFET gates that can be calibrated with respect to one another eliminates the need for an ion meter to be recalibrated before every use, and allows the ion meter to measure the concentration in the solution over an extended period of time.
Claims12
A self-calibrating ion meter that measures a concentration of an ion in a solution, comprising:
- a first ISFET having a first gate with a first gate area effectively exposed to the solution;
- a second ISFET having a second gate with the second gate area effectively exposed to the solution;
- wherein the first area effectively exposed is different from the second area effectively exposed;
- a circuit that measures a first electric activity across the first ISFET and a second electric activity across the second ISFET;
- and
- a processor that calculates the concentration when the solution is simultaneously exposed to the first gate and the second gate, wherein the concentration is calculated as a first function of the first and second electric activities, and a delta between the first and second effective areas exposed.
3 more elements
Dependencies are inferred from the claim text.