Identification of Micro Plastics Using Advanced Raman technologies (IMPART)

Plastic waste in the ocean is becoming an increasingly serious problem; damaging coastal and deep-sea environments, negatively impacting sensitive marine ecosystems and wildlife and even contributing towards climate change by threatening carbon sequestration mechanisms of ocean based picoplankton. In 2015, 381 million tonnes of plastic were produced with only 20% recycled. Manufacturing spills, tyre wear and UV breakdown of plastic waste result in microplastics entering global water systems - it has been estimated that 8.3 million microplastic particles can be found in just one cubic metre of ocean water. There is now increasing concern that these microplastics are finding their way into the wider food chain, with potential for far-reaching health consequences.

The Covid-19 pandemic has exacerbated the problem with huge increases in the use of plastic, disposable, personal protective equipment (PPE) globally. In the UK alone, 28-billion items of PPE have been ordered since the start of the pandemic; a scale replicated globally, along with increased use of other plastics. Acrylic sheet production, for example is up 300% since the start of the outbreak.

Ensuring that waterways and water sources continue to be free of this waste is becoming a significantly urgent problem which has been clearly amplified by the Covid-19 outbreak. This is likely to continue in the near-to-medium term as the virus is combated and more PPE is required. In order to tackle this issue, pollution transport pathways and ultimately their sources must be identified. This requires testing regimes that not only can locate microplastics but also identify their chemical composition, ideally in real-time and on-site. Current measurement systems are limited in their identification and quantification capabilities, either demanding samples be sent to an off-site laboratory for analysis or are completed simply by visual inspection. The fresh-water network (rivers, reservoirs and treatment works) are the transport pathway for primary microplastics entering the marine environment so will be targeted for in-situ analysis with this innovative solution, before application to marine sampling.

IMPART will develop a new handheld, Raman immersion probe that can both identity and characterise the presence of microplastics. Optical methods such as Raman spectroscopy present the opportunity for fast, reliable, high sensitivity in-situ measurement. Typically instrumentation of this type is constrained by the limited etendue or optical throughput characteristics of the spectrometer and probe system. In this project we will develop a new portable high-etendue Raman instrument and immersion probe, exploiting the properties of spatial heterodyne spectrometers.

The key advantage of this spectrometer design is that, for a given resolution, it provides 100-times increase in the etendue than can be achieved with a traditional dispersive spectrometer and, unlike a traditional Fourier transform spectrometer, it has no moving parts. These specifications lend the spectrometer to robust on-site use where rapid measurement turnaround in a challenging environment is required.

IS-Instruments Ltd, an innovative SME are experts in taking optical instrumentation from concept through to market for deployment and operation in challenging environments.