Miniature fiber-optics sensors for free-radical detection in plasma assisted processes

Miniature sensors capable of detecting radicals in non-equilibrium gaseous plasma will be constructed. The sensors will measure the temperature of a short segment of an optical fiber by making the segment a miniature Fabry-Perot interferometer. The segment will be coated with a material of high coefficient for heterogeneous surface recombination of radicals to stable molecules. A plurality of miniature interferometers will be assembled within a sensor, and each interferometer will be coated with different material. Each material will have a specific sensitivity for different radicals. By simultaneous measurements of the temperature of the interferometers coated with different catalysts and development of a smart control unit, the sensor will be able to distinguish between various plasma radicals. The absolute accuracy of the sensors will be about 15%, what is suitable for most industrial applications. The sensors will be first probed in out laboratories. The sensors of best configuration will be probed at three renowned EU plasma laboratories, and finally in industrial environment. A project partner will perform systematic measurements in an industrial reactor useful for the technology of discharge cleaning of various materials, plasma activation of glass products and plasma functionalization of polymeric products. We shall elaborate on the long-term stability and the sensor will reach the TRL6 upon accomplishing the project.