Rapid Monitoring of Scale Precipitation and Inhibition in Geothermal Fluid Using Optical Fiber Sensor Based on Surface Plasmon Resonance

Ai Hosoki*, Kifuyu Sugiura, Takuya Okazaki, Heejun Yang, Hideki Kuramitz*, Akira Ueda, Amane Terai

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

An optical fiber scale sensor based on the detection principle of surface plasmon resonance (SPR) was developed for the rapid, high-sensitivity, real-time evaluation of scale precipitation in geothermal fluids. The optical fiber SPR scale sensor was fabricated by depositing a gold thin film onto the surface of an optical fiber with an exposed core. The optimal gold film thickness of the sensor was determined to be 30 nm, which achieved a refractive index sensitivity of 2140 nm per refractive index unit. A field test was conducted using geothermal brine from the Obama Binary Geothermal Power Plant in Unzen, Nagasaki Prefecture. A conventional optical fiber scale sensor and the SPR sensor were simultaneously assessed using raw and pH-adjusted brines. For the SPR sensor, a peak shift of 0.27 nm/min was observed at a response time of 1 min, whereas no change in transmittance was observed for the conventional sensor until 180 min. After the experiments, a scanning electron microscopy-energy-dispersive spectroscopy analysis was conducted on the sensors, and the findings showed that the deposition of Mg-SiO2 scale did not significantly differ between the two sensors. The developed SPR sensor achieved faster scale precipitation detection (tens of minutes to hours) than the conventional sensor.

Original languageEnglish
Article number74
JournalFibers
Volume12
Issue number9
DOIs
StatePublished - 2024/09

Keywords

  • geothermal scale sensor
  • optical fiber
  • real-time monitoring
  • surface plasmon resonance (SPR)

ASJC Scopus subject areas

  • Ceramics and Composites
  • Civil and Structural Engineering
  • Biomaterials
  • Mechanics of Materials

Fingerprint

Dive into the research topics of 'Rapid Monitoring of Scale Precipitation and Inhibition in Geothermal Fluid Using Optical Fiber Sensor Based on Surface Plasmon Resonance'. Together they form a unique fingerprint.

Cite this