Total Dissolved Inorganic Carbon Sensor Based on Amperometric CO₂ Microsensor and Local Acidification

Area of Science:

• Environmental Science
• Analytical Chemistry
• Electrochemistry

Background:

• Accurate measurement of dissolved inorganic carbon (DIC) is vital for understanding aquatic ecosystems and the global carbon cycle.
• Existing methods for DIC measurement can be time-consuming or lack the spatial and temporal resolution needed for dynamic environments.

Purpose of the Study:

• To develop and validate a novel dipping probe microsensor for high-resolution measurement of total dissolved inorganic carbon (DIC).
• To optimize microsensor design through theoretical simulations for efficient CO2 conversion and rapid response.

Main Methods:

• Fabrication of a microsensor featuring an amperometric CO2 sensor with a localized acidic microenvironment.
• Integration of an acidic CrCl2 oxygen trap to eliminate oxygen interference.
• Theoretical modeling to balance sensor response time and conversion efficiency.
• Calibration and testing in standard solutions, bottled mineral water, and natural seawater samples.

Main Results:

• The microsensor demonstrated a linear response to DIC over a broad range (0-8 mM).
• A limit of detection (LOD) of 5 μM and a 90% response time of 150 seconds were achieved.
• Successful in-situ measurements of DIC in bottled mineral water and seawater were performed.

Conclusions:

• The developed DIC microsensor provides a sensitive and responsive tool for aquatic carbon monitoring.
• This technology enables high spatial and temporal resolution measurements, advancing environmental sensing capabilities.
• The microsensor shows significant potential for applications in environmental monitoring and biogeochemical research.