Highly Sensitive Liquid Permittivity Measurement with Effective Localized Surface Plasmons

In this talk, I will give a scheme to measure the liquid complex permittivity with high sensitivity based an ultra compact effective localized surface plasmons (ELSPs) sensor. Sharp resonance induced by the ELSPs resonator greatly enhance the sensitivity of the measurement. To estimate the complex permittivity of arbitrary unknown liquid, we establish an equivalent circuit model of this ELSPs sensor and build a fitting model based on the frequency shift and return loss. For demonstration, we successfully p redict the complex permittivity of ethanol from 0 to 90% with high precision. This ELSPs based sensor with an ultra compact size of 0.008
$\lambda_{0}^{2}$
and high sensitivity of 0.57% can find many applications (liquid permi ttivity measurement, liquid concentration, liquid testing, etc.) in highly integrated systems.