A Tunable Three-Dimensional Printed Microfluidic Resistive Pulse Sensor for the Characterization of Algae and...

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Accurate characterization of particulates in liquids is crucial for health, food, and environmental monitoring.
• Existing sensors often require a trade-off between speed and specificity.
• Measuring physical properties beyond mere particle count is necessary for comprehensive analysis.

Purpose of the Study:

• To develop a low-cost, high-throughput sensor for classifying particle size, concentration, and shape in liquids.
• To investigate the influence of particle porosity/conductivity on sensor signals.
• To enable rapid and specific detection of microplastics in environmental samples.

Main Methods:

• Utilized additive manufacturing to create a tunable, reusable flow resistive pulse sensor.
• Operated the sensor in real-time to measure particles (2–30 μm) across varying salt concentrations (2.5 × 10^-4 to 0.1 M).
• Correlated signal shape with particle shape for enhanced characterization.

Main Results:

• The sensor demonstrated stability over several days with repeatable measurements.
• Successfully characterized algae (spherical and rod) and microplastics from tea bags.
• Developed a method to specifically identify microplastics via a conductive pulse signal, differentiating them from smooth-surfaced particles.

Conclusions:

• The developed sensor offers a rapid (1 mL/min) and specific method for detecting and quantifying microplastics and algae in liquid samples.
• The technology provides a new tool for environmental monitoring, distinguishing microplastics based on their unique conductive properties.
• The ability to correlate signal and particle shape offers an additional layer of particulate characterization.