Continuous intra-arterial blood pH monitoring by a fiber-optic fluorosensor

Weizhong Jin, Lingxiang Wu, Yuanlin Song, Jinjun Jiang, Xiaodan Zhu, Dawei Yang, Chunxue Bai

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


Continuous intra-arterial blood pH monitoring is highly desirable in clinical practice. However, devices with appreciable accuracy are still not commercially available to date. In this study, we present a fiber-optic fluorosensor that can be used to continuously and accurately measure blood pH changes. The pH sensor is developed based on a proton-sensitive fluorescence dye, N-allyl-4-(4′-methyl-piperazinyl)-1,8-naphthalimide, which is bonded covalently to an optical fiber through heat polymerization. Fluorescence intensity was recorded after the sensor was exposed to different pH buffer solutions or intra-arterial blood in rabbits. Fluorescence intensity with emission peak at 510 nm decreased immediately as the blood pH increased. Linear and reproducible responses were observed when pH ranges from 6.8 to 8.0 with resolution of 0.03 pH units. The correlation coefficient between the pH sensor and the conventional blood gas analyzer was 0.93 in vivo (n = 75, p < 0.001) with a bias and precision of -0.02 ± 0.08 pH units. The pH sensor was stable during measurement for at least 72 h. The pH sensor is not sensitive to fluctuations of various ions concentrations and plasma osmosis at pathophysiological limits, suggesting that it is useful for the continuous measurement of blood pH at various clinical settings.

Original languageEnglish
Article number5696742
Pages (from-to)1232-1238
Number of pages7
JournalIEEE Transactions on Biomedical Engineering
Issue number5
StatePublished - May 2011
Externally publishedYes


  • Biomedical monitoring
  • fluorescence
  • optical fibers
  • pH sensor


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