Measurement Technique for Permeation Coefficient of Gases

On the other hand, because the pressure of both sides is the same with the isopressure technique, measurement can be made even in the presence of water. Generally, a technique called the electrode method is used to measure the permeability. This electrode method fills 0.5 N 

It was probably Yasuda and Stone who first attempted to measure oxygen permeability using the oxygen electrode in the presence of water [272]. Later, the measurement technique was improved. Aiba et al. [273] developed a technique termed the direct method in which a sample is adhered directly to the electrode. On the other hand, Hwang et al. [274] developed the indirect method where a membrane is adhered to the interface between the gaseous and liquid phases. Initially, both methods studied mainly hydrophobic membranes. Today, however, both techniques have been improved to use both hydrophobic and hydrophilic (gel) membranes, and are established as the gaseous permeation measurement techniques in the presence of water. In the following, the measurement devices and their procedures will be discussed. 

3 A measurement device for oxygen permeability using the direct method [275]. 

On the other hand, the cathode side has the following reaction  

Due to the movement of electrons created by this reaction at both electrodes, current will flow. The diffusion coefficient of oxygen is slower than the oxidation-reduction reaction at the electrode. The steady-state current /, which is proportional to the diffusion coefficient of oxygen, can be expressed in microamperes by the following equation  

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