Portable sub-terahertz resonance spectrometer combined with microfluidic sample cell

Abstract

Radiation in the Terahertz frequency range interacts with vibrations in the weakest molecular couplings such as hydrogen bonding, van der Waals forces, and hydrophobic interactions. The work presented demonstrates our efforts towards the development of a microfluidic device as the sample cell for presenting liquid samples within the detection region of a novel sub-THz spectrometer. The continuous-wave, frequency-domain spectrometer, operating at room temperature between 315 and 480 GHz with spectral resolution of 0.3 GHz, already demonstrated highly intense and specific signatures from nanogram samples of dry biological molecules and whole bacterial cells. The very low absorption by water in this sample cell will allow for the use of liquid samples to present cells and molecules in their natural environment. The microfluidic device design utilizes a set of channels formed with metal sidewalls to enhance the interaction between the THz radiation and the sample, increasing the sensitivity of the system. Combined with near field effects, through use of a detection probe close to the surface of the sample cell, spatial resolution less than the diffraction limit can be achieved, further reducing the amount of sample required for analysis. This work focuses on the design, and fabrication methods, which will allow implementation of the microfluidic sample cell device within the THz spectrometer. The device will be utilized for characterization of different cell types, showing that THz interrogation of liquid samples is possible.