Ultra-sensitive isopropanol biochemical gas sensor (Bio-sniffer) for monitoring of human volatiles

Po Jen Chien, Takuma Suzuki, Ming Ye, Koji Toma, Takahiro Arakawa, Yasuhiko Iwasaki, Kohji Mitsubayashi

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


Our groups have previously developed a biochemical gas sensor to measure isopropanol (IPA) in exhaled air and have applied it for breath IPA investigation in healthy subjects and diabetes patients. In this study, the original bio-sniffer was modified with a series of components that improved the limit of detection (LOD). First, the modified IPA bio-sniffer used a C8855-type photomultiplier tube (PMT) that performed well in the photon sensitivity at the peak wavelength of nicotinamide adenine dinucleotide (NADH) fluorescence. Second, the multi-core bifurcated optical fiber, which incorporated 36 fibers to replace the previous dual-core type, enhanced the fluorescence collection. Third, the optical fiber probe was reinforced for greater width, and the flow-cell was redesigned to increase the area of the enzyme-immobilized membrane in contact with the air sample. These modifications lowered the detection limit to 0.5 ppb, a significant increase over the previous 1.0 ppb. Moreover, the modified bio-sniffer successfully analyzed the IPA concentration in exhaled air from a volunteer, which confirmed its capability for real-world sample detection. The modified bio-sniffer is more applicable to breath measurement and the detection of other extremely-low-concentration samples.

Original languageEnglish
Article number6827
Pages (from-to)1-13
Number of pages13
JournalSensors (Switzerland)
Issue number23
Publication statusPublished - 2020 Dec 1
Externally publishedYes


  • Biosensor
  • Breath isopropanol
  • Gas sensor
  • NADH
  • Secondary alcohol dehydrogenase
  • Volatile organic compounds

ASJC Scopus subject areas

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


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