  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.
