Method of measuring humidity using an electrochemical cell

摘要

In a method of measuring humidity by using an electrochemical cell, the method comprises applying a voltage across the pair of electrodes to obtain a characteristic curve between the voltage applied and electrical current. The characteristic curve starts with a first flat portion in which a first diffusion limit current remains generally constant within a predetermined voltage range and passes through a point of inflection in which a second differential derivative of the characteristic curve falls on zero at certain voltage, and ends up with a second flat portion in which a second diffusion limit current remains generally constant within a predetermined voltage range. The point of the inflection is uniquely determined regardless of a humidity level of the gas at a constant temperature and oxygen concentration. The humidity level in the gas is obtained by reading the point of the inflection, and the intensity of the first and second diffusion limit current and then comparing the diffusion limit current with the inflection as a reference current.