An intrinsic biochemical concentration sensor using a polymer optical fibre Bragg grating

Wei Zhang, David J. Webb, Gang-Ding Peng

Research output: Chapter in Book/Published conference outputConference publication


A new type of fibre-optic biochemical concentration sensor based on a polymer optical fibre Bragg grating (POFBG) is proposed. The wavelength of the POFBG varies as a function of analyte concentration. The feasibility of this sensing concept is demonstrated by a saline concentration sensor. When polymer fibre is placed in a water based solution the process of osmosis takes place in this water-fibre system. An osmotic pressure which is proportional to the solution concentration, will apply to the fibre in addition to the hydraulic pressure. It tends to drive the water content out of the fibre and into the surrounding solution. When the surrounding solution concentration increases the osmotic pressure increases to drive the water content out of the fibre, consequently increasing the differential hydraulic pressure and reducing the POFBG wavelength. This process will stop once there is a balance between the osmotic pressure and the differential hydraulic pressure. Similarly when the solution concentration decreases the osmotic pressure decreases, leading to a dominant differential hydraulic pressure which drives the water into the fibre till a new pressure balance is established. Therefore the water content in the polymer fibre - and consequently the POFBG wavelength - depends directly on the solution concentration. A POFBG wavelength change of 0.9 nm was measured for saline concentration varying from 0 to 22%. For a wavelength interrogation system with a resolution of 1 pm, a measurement of solution concentration of 0.03% can be expected.
Original languageEnglish
Title of host publicationMicro-structured and specialty optical fibres
EditorsKyriacos Kalli, Alexis Mendez
Number of pages6
Publication statusPublished - 2012
EventMicrostructured and specialty optical fibres - Brussels, Belgium
Duration: 17 Apr 201219 Apr 2012

Publication series

NameSPIE proceedings
ISSN (Print)0277-786X


ConferenceMicrostructured and specialty optical fibres

Bibliographical note

Zhang, Wei; Webb, David J.; Peng, Gang-Ding. An intrinsic biochemical concentration sensor using a polymer optical fibre Bragg grating. In: Micro-structured and specialty optical fibres. ed. Kyriacos Kalli; Alexis Mendez. Vol. 8426 SPIE, 2012.

Copyright 2012 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.


  • Fibre Bragg grating
  • osmosis process
  • solution concentration
  • polymer swelling
  • PMMA


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