Continuous and automatic hexavalent chromium sensing using an ion-selective membrane deposited ion-sensitive...

Area of Science:

• Environmental Science
• Analytical Chemistry
• Sensor Technology

Background:

• Heavy metal ion testing is crucial for water quality monitoring in domestic, agricultural, and industrial settings.
• Current methods for heavy metal detection are often time-consuming, require complex sample preparation, and necessitate specialized equipment and trained personnel.

Purpose of the Study:

• To develop a novel sensor for real-time and continuous detection of hexavalent chromium (Cr(VI)) in water.
• To overcome the limitations of existing water testing methodologies by proposing a portable and user-friendly device.

Main Methods:

• Fabrication of an ion-sensitive field-effect transistor (ISFET) sensor coated with a polyvinyl chloride (PVC)-based ion-selective membrane (ISM) for Cr(VI) detection.
• Optimization of ISM parameters and buffer conditions to enhance sensor sensitivity and specificity.
• Integration of a microfluidic control system with the Cr(VI) ISM-ISFET for continuous, automated sensing in real water samples.

Main Results:

• The developed Cr(VI) ISM-ISFET system demonstrated successful differentiation of Cr(VI) concentrations between 10⁻⁶ M and 10⁻⁴ M in ditchwater.
• The sensor's performance met the guideline values for industrial wastewater discharge.
• The system facilitated continuous operation through precise mixing of water samples and buffer solutions.

Conclusions:

• The integrated, portable Cr(VI) ISM-ISFET system provides a viable solution for continuous, on-site water quality monitoring.
• This technology can be applied in diverse settings, including households, factories, farms, and orchards, for effective Cr(VI) detection.
• The simplified fabrication and operation of the sensor enable wider accessibility for environmental monitoring.