New tools for tracking microplastics in water

KEY INSIGHTS

  • Microwave signals can detect microplastics in water with simple on-site filtration: Changes in microwave resonance frequency caused by suspended plastic particles allow direct, label-free detection of microplastics in liquid samples. With simple on-site filtrations, a wide range of MP particle sizes can be detected.
  • Particle size and concentration can be measured simultaneously: Sensitivity-enhanced resonator designs separate size and concentration signals by analyzing how resonance shifts evolve over time, enabling accurate characterization across a wide range of particle sizes.
  • Flow-through sensing enables individual particle analysis: Moving from static samples to microfluidic flow allows each particle to be interrogated as it passes the sensor, generating a unique microwave “fingerprint.”
  • Machine learning enables automated particle classification: AI models analyze microwave fingerprints in real time to classify particle type while also resolving size and concentration, supporting fully automated detection.
  • The platform bridges lab research and field monitoring: The integrated microwave–microfluidic and AI approach represents a major step toward portable, high-throughput, and intelligent microplastics monitoring systems.
     

WHY THIS MATTERS FOR MONITORING OR REMEDIATION

  • Supports real-time monitoring: Continuous, flow-through detection makes it possible to track microplastics dynamically rather than relying on delayed lab analysis.
  • Reduces cost and complexity: Microwave-based detection lowers operational barriers for routine monitoring in environmental and engineered water systems.
  • Enables scalable and automated surveillance: AI-powered classification reduces reliance on expert interpretation and supports deployment at multiple sites or over long time periods
Overview of the flow-through microwave-microfluidic platform for microplastic detection

RESEARCH PROCESS

This research developed a microwave–microfluidic system for detecting microplastics through three progressive stages. In the first stage, the team demonstrated that microwave sensors combined with microfluidic sample reservoirs could detect microplastics suspended in water by measuring small changes in electrical properties. These changes increased as more particles were present, allowing the system to reliably measure the overall concentration of microplastics in a sample.

In the second stage, the system was further improved to increase sensitivity and extract more information from the same measurement. By refining the sensor design and analyzing how the microwave signal changed over time, the platform was able to determine both the size and concentration of microplastics at the same time. This removed the need for multiple tests and expanded the range of particle sizes that could be detected.

In the most recent stage, the platform was adapted from static testing to a flow-through system that can analyze particles one by one. This flow through system leveraged simple filtration to separate microplastic sizes into some ranges, for example 100-150 micrometers, and 150-300 micrometers. As individual microplastics move through the sensor, each produces a unique microwave signal that can be analyzed using machine-learning methods. This allows particle type, size, and concentration to be identified in real time, moving the technology closer to portable, automated systems for practical and field-based monitoring.
 

RESEARCHERS & COLLABORATORS

Ren

Prof. Carolyn L. Ren
Professor, University of Waterloo: Expert in the development of microfluidic and microwave sensing technologies for environmental and biomedical applications.
 

Maziar

Maziar ShafieiDarabi
PhD Researcher: Led device design, experimental validation, and AI-based analysis for microwave–microfluidic microplastics detection.


Key collaborators and partners

  • Z. Abbasi, A. YazdaniCherati, X. Wang, S. Slowinski, S. Li
  • Waterloo Microfluidics Lab
  • Calgary Sensor Lab
  • QuantWave Technology Inc. (Canada), instrumentation support
  • Philippe Van Cappellen’s lab
     

KEY PUBLICATIONS