Even though the absorption of terahertz radiation from water is approximately two orders of magnitude weaker than in the mid-infrared it is still around 200 cm -1 at 1 THz, which limits the path length of the cuvette that can be used for transmission measurements to around 100 µm in terms of trading off dynamic range and spectral bandwidth for the measurement. However, such a path length is sufficient for crystallisation experiments and terahertz spectroscopy combined with microfluidics offers the opportunity to measure samples containing water with high sensitivity and over a wide frequency range. Similar approaches using thin cuvettes in transmission were previously found to be useful to investigate biomaterials such as proteins and DNA , .