Opto-chemical method for ultra-low oxygen transmission rate measurement

A highly sensitive alternative to established methods for measuring oxygen transmission rates of ultra-barrier membranes is presented. The key idea is the employment of an opto-chemical sensor (a luminescent dye immobilized in a matrix) which has vital advantages over electrochemical sensors, such as consumption-less detection and extraordinary sensitivity. The luminescent response to modulated light, which is altered in the presence of oxygen, is recorded by an opto-electronic instrument in a non-invasive manner. Provided with said sensing system, a reusable stand-alone permeation cell was developed. Unlike in conventional devices, the permeating oxygen is accumulated while being simultaneously monitored. The demonstrator unit achieves a limit of detection in the 10^-5 cm³ m^-2 day^-1 bar^-1 regime. It is therefore among the most sensitive O₂ permeability testers, outperforming commercial instruments by two orders of magnitude, yet offering reusability and similar convenience in operation.