Highly sensitive terahertz spectroscopy in microsystem

We herein present a microfluidic system dedicated to THz spectroscopy of aqueous solutions. This device is able to reach a state of the art sensitivity of 5 mg mL(-1), while requiring only small sample quantities and a low power source. Hydration of BSA, lysozyme and chymotrypsine proteins is studied inside microchannels and hydration numbers are computed, showing that the developed system is well suited for quantitative analysis. Moreover, coupled with advanced chemometrics algorithms, this system can become a tool for fundamental research and for the understanding of biochemical processes. Here, the hydration shell structure is discussed by chemometric analysis of the measured absorption spectra. Two spectral behaviours are observed and can be explained by Molecular Dynamics simulations. This methodology could be considered as a key element of a labon-a-chip for biological liquid metrology.