A micro-machined optical fibre cantilever as a miniaturised pH sensor

Jun Li, Frank Albri, Robert R. J. Maier, Wenmiao Shu, Jining Sun, Duncan P. Hand, William N. MacPherson

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A micro-cantilever fabricated using a combination of picosecond-laser machining and focused ion beam milling directly onto the end of a standard telecommunications optical fiber is demonstrated as a liquid pH sensor. Conventional pH meters typically require relatively large reaction volumes up to ~50 mL, which is not always convenient. The micro-scale nature of this sensor offers the potential for pH measurement on a smaller sample volume down to micro-liter. The fiber end-tip cantilever is coated with a pH sensitive layer, and the pH-induced deflection is monitored interfermetically. A detectable pH range from 4.0 to 10.0 is demonstrated for the cantilevers coated with 16-mercapto-hexadecanoic-1-acid as the functional layer, and a detectable pH range from 4.0 to 9.0 is demonstrated for the cantilevers coated with Al2O3 as the functional layer.
Original languageEnglish
Pages (from-to)7221-7228
Number of pages8
JournalIEEE Sensors Journal
Issue number12
Early online date26 Aug 2015
Publication statusPublished - 31 Dec 2015


  • optical fiber sensors
  • optical fibers
  • cavity resonators
  • temperature measurement
  • temperature sensors

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