Infrared hollow optical fiber probe for localized carbon dioxide measurement in respiratory tracts

Takashi Katagiri, Kyosuke Shibayama, Takeru Iida, Yuji Matsuura

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


A real-time gas monitoring system based on optical absorption spectroscopy is proposed for localized carbon dioxide (CO2) measurement in respiratory tracts. In this system, a small gas cell is attached to the end of a hollow optical fiber that delivers mid-infrared light with small transmission loss. The diameters of the fiber and the gas cell are smaller than 1.2 mm so that the probe can be inserted into a working channel of common bronchoscopes. The dimensions of the gas cell are designed based on absorption spectra of CO2 standard gases in the 4.2 µm wavelength region, which are measured using a Fourier-transform infrared spectrometer. A miniature gas cell that is comprised of a stainless-steel tube with slots for gas inlet and a micro-mirror is fabricated. A compact probing system with a quantum cascade laser (QCL) light source is built using a gas cell with a hollow optical fiber for monitoring CO2 concentration. Experimental results using human breaths show the feasibility of the system for in-situ measurement of localized CO2 concentration in human airways.

Original languageEnglish
Article number995
JournalSensors (Switzerland)
Issue number4
Publication statusPublished - 2018 Apr


  • Carbon dioxide measurement
  • Functional bronchoscopy
  • Infrared absorption spectroscopy
  • Optical fiber sensor

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Atomic and Molecular Physics, and Optics
  • Instrumentation
  • Electrical and Electronic Engineering


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