Patent ID: 7251384

Claim:
An optical fiber pH sensor ( 100 ) for the measurement of the pH of aqueous solutions, wherein said sensor comprises: A) a generally cylindrical outer body ( 101 ) including: a) a central part ( 110 ), comprising: i) a first compartment ( 117 a ) containing a set of disc units ( 130 ) of a pH-sensitive hydrogel, said set being contained by a screen ( 116 ); ii) a second compartment ( 117 b ) containing a mechanical transducer ( 123 ) for transmitting strain to an optical fiber ( 121 ) containing a Bragg grating ( 122 ), the limits of said compartment being marked by a movable disc ( 118 ) between said first ( 117 a ) and second ( 117 b ) compartments and a disc ( 119 ) for attachment of an optical fiber ( 121 ); b) covers ( 115 a ) and ( 115 b ) at the ends of said outer body ( 101 ), and where: the change in pH of the tested solution causes a change in the hydrogel hydrodynamic volume, the strain caused by such volume change being transmitted to the Bragg grating ( 122 ) by the mechanical transducer ( 123 ) so as to alter the Bragg wavelength, said alteration being measured with the aid of usual techniques for wavelength measurement.