Overview

• Researchers from the University of Melbourne and the University of Stuttgart report the method in Nature Photonics, describing detection, sizing and counting of particles at the nanoplastic scale.
• The device uses an array of size-graded cavities etched into gallium arsenide that capture matching particles and reveal their presence through visible color shifts under standard optical microscopes.
• Filled cavities change hue, enabling simple image-based counts with a basic camera and avoiding expensive tools such as electron microscopes.
• Validation included polystyrene beads and a mixed, unfiltered lake-water sample containing sand and biological material, showing distinct size bands without prior separation.
• The teams are pursuing portable, commercial test devices and plan wider environmental trials and tests on biological samples before routine deployment.