Multimodal optical detection and toxicity testing of microplastics in the environment

Microplastics are small plastic particles the size of less than 5 millimeters from cosmetics or results of abrasion and decomposition of plastic waste. The tremendous marine pollution by plastic particles and fibers and the increasing presence in the human environment from drinking water reservoirs to waste water demands for an environmental management and effective detection methods. The uptake of microplastics by living organisms may cause injuries of the gastrointestinal tract, trigger inflammation or cause cell toxicity by intrinsic particle properties or adsorbed pollutants. The urgent need for methods to identify microplastics in the environment, its sources of input and the risk of microplastic particles is the objective of the research project MicroPlastiCarrier. The project develops new tools for the optical detection and identification of microplastic particles from wastewater by a multiwavelength approach. The multiple labelfree optical toolbox is based on digital holographic microscopy using wavelengths from the visible to mid infrared. In order to monitor particle uptake minimally-invasively in living organisms and cellular specimens in a label-free manner, we applied high resolution optical coherence tomography (OCT) and multi-spectral digital holographic microscopy (DHM). In combination with microfluidics technologies as flow cytometry the project plans to identify particles based on size and their absorption and refraction index properties at several wavelengths. The technology should overcome the limitations of state of the art FT-IR.