title: Photonic crystal fiber interferometric pH sensor based on polyvinyl alcohol/polyacrylic acid hydrogel coating.
abstract: We present a simple photonic crystal fiber interferometer (PCFI) that operates in reflection mode for pH measurement. The sensor is made by coating polyvinyl alcohol/polyacrylic acid (PVA/PAA) hydrogel onto the surface of the PCFI, constructed by splicing a stub of PCF at the distal end of a single-mode fiber with its free end airhole collapsed. The experimental results demonstrate a high average sensitivity of 0.9 nm/pH unit for the 11 wt.% PVA/PAA coated sensor in the pH range from 2.5 to 6.5. The sensor also displays high repeatability and stability and low cross-sensitivity to temperature. Fast, reversible rise and fall times of 12 s and 18 s, respectively, are achieved for the sensor time response.
authors.forename: Pengbing
authors.initials: P
authors.lastname: Hu
authors.forename: Xinyong
authors.initials: X
authors.lastname: Dong
authors.forename: Wei Chang
authors.initials: WC
authors.lastname: Wong
authors.forename: Li Han
authors.initials: LH
authors.lastname: Chen
authors.forename: Kai
authors.initials: K
authors.lastname: Ni
authors.forename: Chi Chiu
authors.initials: CC
authors.lastname: Chan
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D002138:Calibration; D003460:Crystallization; D004867:Equipment Design; D020100:Hydrogels / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007368:Interferometry / Q000295:instrumentation* / Q000379:methods; D008422:Materials Testing; D055620:Optical Phenomena; D017785:Photons; D011142:Polyvinyl Alcohol / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
chemical_list: D000180:Acrylic Resins; D020100:Hydrogels; C006903:carbopol 940; D011142:Polyvinyl Alcohol