Pressure compensation of membranetype sensors
Abstract
Abstract In a sensor for measuring the quantity of a substance in a compositionof matter of the type including a membrane which is permeable to the substance and substantially impermeable to liquid and ions, the permeability of the membrane being a function of the pressure thereon, the sensor providing an electrical output signal which is a function of the quantity of the substance in the composition of matter, there is disclosed an improvement consisting of a method and means for accurately compensating the output of the sensor for the effect of pressure upon membrane permeability by multiplying the output signal by the function ekp thus cancelling the pressure effect which is given by the function Poe-kp where Po=membrane permeability at zero pressure, p=absolute pressure, and k=a membrane constant. According to a preferred embodiment of the invention, such multiplication is achieved through the use of a pressure-driven, variable resistance in the feed-back loop of an operational amplifier.
Inventors
- 👤 Malbone W Greene
Bibliographic Details
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