Identification and characterization of various plastics using THz-spectroscopy

TL;DR

This paper demonstrates the use of THz spectroscopy to identify and characterize common plastics by their unique spectral fingerprints, aiming to enable future detection of microplastics in biological tissues.

Contribution

The study provides the first analysis of specific THz spectral fingerprints for four widely used plastics, advancing the use of THz spectroscopy for plastic identification.

Findings

Identified unique THz absorption fingerprints for four common plastics.

Demonstrated the capability of THz spectroscopy to distinguish different polymers.

Contributed to developing a method for detecting microplastics in biological tissues.

Abstract

THz spectroscopy has reached imaging capability with a spatial resolution of a few micrometres. This property enables measurements and imaging of biological samples like cells. THz photons have very low photon energies in the millielectronvolt range. These energies interact mainly with vibrations in the molecules. Therefore, the investigated samples are neither ionized nor their DNA damaged, making this the perfect method for application on living cell tissue. In the future, material databases with absorption spectra will empower this method to distinguish even artificial particles like microplastics inside biological tissue. Current research aims at the impact of plastic nanoparticles on cell tissue considering various aspects. One of them is the investigation of the potential harm, the interaction of these particles with human body cells can cause, as these highly abundant particles are found anywhere in the environment. THz absorption spectroscopy offers the opportunity to investigate the polymers and identify them using their specific absorption lines as a fingerprint. In this publication, we study different polymers and analyse their particular fingerprints in the THz frequency spectrum from 0.1 up to 4 THz using a commercially available THz spectrometer. With this work we are contributing to the development, using THz waves for imaging, by identifying the fingerprints of the four most used plastics by humankind. At the end of this development, we envision a method to investigate the influence of nanometre-sized plastic particles on the human body and other biological organisms.