Lithography Process Verification on Porous PET Membranes for Cell Measurements Using THz-TDS Imaging

Thin porous PET membranes are used for growing epithelial cells on top, employed within a cultivation environment for cells originating from the lung. Structuring those membranes with a resonator array by using a lithographic process enables a very sensitive electromagnetic measurement of changes within the epithelial cells, providing a biosensing platform for cell vitality measurements up to 3 THz. Due to the low thickness with $12 \mu \mathrm{m}$ and $23 \mu \mathrm{m}$ of the membranes and its microscopic pores, the process is prone to fabrication issues. In this work, the verification of this lithographic process is performed by a THz time-domain spectrometer with imaging capabilities. Additionally, the complex permittivity of the membrane material is characterized in the THz region.