Enhancing Hyperspectral Imaging for Fast Detection of Microplastics
The global environment is grappling with a severe plastic pollution crisis, as the annual production of over 430 million tonnes of plastic overwhelms our planet. A significant portion, approximately two-thirds, comprises short-lived items that swiftly transform into waste, ultimately polluting our oceans and frequently infiltrating the human food chain.
Among the enduring consequences of the plastic pollution crisis, microplastics stand out as one of the most harmful and persistent threats to both human well-being and the overall health of our planet.
Microplastics, with diameters of up to five millimetres, make their way into the ocean through a variety of means, including the breakdown of marine plastic debris, plumbing runoff, leaks from manufacturing facilities, and other sources.
Plastic pollution has emerged as a pressing concern for both aquatic and terrestrial ecosystems. Nevertheless, the rapid detection of small microplastics remains a challenge. A study published on MethodsX, introduce a method for swiftly identifying microplastics through hyperspectral imaging, leveraging the enhancement of hyperspectral camera Pika IR+ (formerly Pika NIR-640).
Following these optimizations, the detection resolution of each pixel was significantly improved, reducing from 250 µm to a remarkable 14.8 µm. With this refined system, the study were able to rapidly identify microplastics as small as 100 µm. These findings hold promise for the practical application of our innovative method in expediting the detection of microplastics, ultimately contributing to a more comprehensive comprehension of the microplastic pollution crisis.
- Readily available hyperspectral imaging system was fine-tuned to expedite microplastic detection.
- This optimization involves the utilization of infrared lamps, the implementation of a macro-photography technique, and exposure adjustments.
- With the refined system, microplastics as small as 100 µm can be swiftly identified.
Figure 1: The primary components of the hyperspectral imaging system (a) were altered (b). Polyethylene particles were positioned on a gold-coated polycarbonate filter on the right side. Instead of the original white light lamps, a symmetrical arrangement of near-infrared (NIR) lamps was employed, and an extension tube was added between the camera and the lens for macro-photography.
Research Method Details using Hyperspectral Camera
Traditionally, investigations into environmental microplastics have primarily relied on the collection, separation, and quantification of samples within laboratory settings. Methods such as visual inspection, Fourier transform infrared and Raman spectroscopy, and pyrolysis-gas chromatography have been pivotal in identification. Nonetheless, these approaches are both time-consuming and labour-intensive.
In contrast, hyperspectral imaging techniques offer an expedient and efficient means for quantifying environmental microplastic particles. This study present a comprehensive technical guide for the rapid detection of small microplastics using hyperspectral imaging methods. It has adapted a commercially available hyperspectral imaging system for this purpose and confirmed its capability to identify microplastics as small as 100 µm.
Default Hyperspectral Imaging System
Microplastic detection in this study was carried out using a benchtop hyperspectral imaging system manufactured by Resonon Inc. (USA) as depicted in Figure 2. The system is equipped with a hyperspectral camera, the Pika IR+ (formerly NIR-640). This camera features a two-dimensional InGaAs array detector with a pixel size of 15 µm and is paired with a 25 mm focal length lens, providing a field of view spanning 21.7°. Hyperspectral imagery is captured across the near-infrared (NIR) wavelengths ranging from 900 to 1700 nm, with a spectral sampling resolution of 2.5 nm.
Figure 2: Hyperspectral Imaging Benchtop System used for detecting microplastics (before modification)
