We present a device and method for performing vector transmission spectroscopy on biological
specimens at terahertz (THz) frequencies. The device consists of artificial dielectric birefringence obtained
from silicon microfluidic grating structures. The device can measure the complex dielectric function of a liquid,
across a wide THz band of 2 to 5.5 THz, using a Fourier transform infrared spectrometer. Measurement data from a
range of liquid specimens, including sucrose, salmon deoxyribonucleic acid (DNA), herring DNA, and bovine
serum albumin protein solution in water are presented. The specimen handling is simple, using a microfluidic
channel. The transmission through the device is improved significantly and thus the measurement accuracy
and bandwidth are increase
