Robust and sensitive metamaterial-inspired microfluidic sensor for liquids with low dielectric constants

Abstract

In this paper, we present a low-cost, robust and high-sensitivity microwave-microfluidic sensor based on Asymmetric Electric Spilt-Ring Resonator (AESRR). The designed AESRR structure based on FANO resonance can improve the sensitivity of sensor greatly. The proposed sensor, which operates at around 10.50 GHz in the X-band and has a higher operating frequency over traditional microwave sensors, is designed to identify liquid samples with low permittivity and determine their dielectric constants. T-shape channels are integrated to the sensor by grooving in the substrate to improve device integration. The stable measured results show that the resonant frequency shift ∇f is around 60 MHz for a tiny permittivity change ∇ε of 1. To estimate the dielectric constants of the liquids under test, a fitting model was built and the numerical calculation agree well with the measured data. A parabolic equation was established and can be used to determine the dielectric constant of liquid samples with low dielectric constant according to the measured resonant frequency. As a passive device, this metamaterial-microfluidic sensor offers a potential lab-on-chip solution for liquids with low dielectric constant effectively.