Integrated on-chip THz sensors for fluidic systems fabricated using flexible polyimide films

We investigate the use of an on-chip terahertz (THz) frequency sensor formed on a flexible, thin-film polyimide substrate to measure the properties of liquids encapsulated in a glass-walled capillary. We observe changes in the attenuation and velocity of the time-domain THz signal, which allows extraction of the broadband THz refractive index and relative attenuation coefficients of the liquid. The technique is used for sensing members of a homologous series of primary alcohols, and the results compared with those obtained from a free-space THz-TDS system.