Text this: Optical fiber Fabry-Perot interferometer with pH sensitive hydrogel film for hazardous gases sensing

   _____   __   __    ______     ___      _  _   
  / ___//  \ \\/ //  /_   _//   / _ \\   | \| || 
  \___ \\   \ ` //     | ||    / //\ \\  |  ' || 
  /    //    | ||     _| ||   |  ___  || | .  || 
 /____//     |_||    /__//    |_||  |_|| |_|\_|| 
`-----`      `-`'    `--`     `-`   `-`  `-` -`