Abstract-Self-referenced sensing based on terahertz metamaterial for aqueous solutions

http://apl.aip.org/resource/1/applab/v102/i15/p151109_s1?isAuthorized=no

Xiaojun Wu¹, Xuecong Pan¹, Baogang Quan¹, Xinlong Xu^1,2, Changzhi Gu¹, and Li Wang¹

¹Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
²Nanobiophotonic Center, State Key Laboratory for Incubation Base of Photoelectric Technology and Functional Materials, Institute of Photonics & Photon-Technology, Northwest University, Xi'an 710069, China 

We demonstrated a self-referenced sensing method in reflection geometry for characterizing aqueous solutions based on terahertz metamaterials. The sensing signal and the reference signal are taken in one measurement from different interfaces of the substrate. For ethanol-water mixture and aqueous solution of NaCl, the line-shape of the modulated response shows distinct polarity, while the peak-valley value near resonant region depends linearly on the solution concentration. These observations result from the variation of dielectric environment near the interface between the metamaterials and the aqueous solutions. This method holds promise for future application in monitoring real aqueous biosystems and ecological water systems.