High-Sensitivity Metamaterial-Inspired Sensor for Microfluidic Dielectric Characterization

TLDR

The paper proposes a metamaterial‑inspired microwave microfluidic sensor. The sensor employs a microstrip‑coupled complementary split‑ring resonator whose resonant electric field is perturbed by a micro‑channel carrying the liquid, and the resulting frequency and attenuation shifts are empirically related to the sample’s complex permittivity. The sensor operates with a sample volume five orders of magnitude smaller than the wavelength squared and is compatible with lab‑on‑chip platforms.

Abstract

A new metamaterial-inspired microwave microfluidic sensor is proposed in this paper. The main part of the device is a microstrip coupled complementary split-ring resonator (CSRR). At resonance, a strong electric field will be established along the sides of CSRR producing a very sensitive area to a change in the nearby dielectric material. A micro-channel is positioned over this area for microfluidic sensing. The liquid sample flowing inside the channel modifies the resonance frequency and peak attenuation of the CSRR resonance. The dielectric properties of the liquid sample can be estimated by establishing an empirical relation between the resonance characteristics and the sample complex permittivity. The designed microfluidic sensor requires a very small amount of sample for testing since the cross-sectional area of the sensing channel is over five orders of magnitude smaller than the square of the wavelength. The proposed microfluidic sensing concept is compatible with lab-on-a-chip platforms owing to its compactness.