Highly sensitive and fast responsive fiber-optic modal interferometric pH sensor based on polyelectrolyte complex and polyelectrolyte self-assembled nanocoating

Mingjie Yin, Bobo Gu, Qiang Zhao, Jinwen Qian, Aping Zhang, Quanfu An, Sailing He

Research output: Journal article publicationJournal articleAcademic researchpeer-review

48 Citations (Scopus)


A new fiber-optic pH sensor is demonstrated by coating negatively charged polyelectrolyte complex (PEC-) nanoparticles, made of sodium carboxymethyl cellulose and poly(diallyldimethylammonium chloride) (PDDA), and positively charged PDDA on the surface of a thin-core fiber modal interferometer (TCFMI) with a layer-by-layer (LbL) electrostatic self-assembly method. The fabricated TCFMI pH sensor has different transmission dip wavelengths under different pH values and shows high sensitivities of 0.6 nm/pH unit and -0.85 nm/pH unit for acidic and alkaline solutions, respectively, and short response time of 30-50 s. The LbL electrostatic self-assembly process of a PEC-/PDDA multilayer is traced by quartz crystal microbalance and shows a fast thickness growth. Atomic force microscopy shows the root mean square (RMS) surface roughness of electrostatic self-assembly nanocoating of polyelectrolyte complex/polyelectrolyte is much higher than that of polyelectrolyte/polyelectrolyte due to the larger size of PEC-colloidal nanoparticles. The enhanced RMS surface roughness and thickness of the nanocoating can shorten the response time and raise the sensitivity of the TCFMI pH sensor, respectively. In addition, the TCFMI pH sensor has highly reversible performance and good durability.
Original languageEnglish
Pages (from-to)3623-3631
Number of pages9
JournalAnalytical and Bioanalytical Chemistry
Issue number10
Publication statusPublished - 1 Apr 2011
Externally publishedYes


  • Electrostatic self-assembly
  • Optical fiber
  • pH sensor
  • Refractive index

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry

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