Improved Split - Ring Resonator for Microfluidic Sensing

We present a method of making low loss split-ring resonators for microfluidic sensing at microwave frequencies using silver coated copper wire. We show that a simple geometric modification and the use of square cross-section wire give greater electric field confinement in the capacitive region of the resonant sensor. We use a combination of theoretical analysis, finite element simulations and empirical measurements to demonstrate the subsequent increases in the sensitivity of these split ring resonators for complex permittivity measurements of some common solvents.