An Improved RF Sensor to Determine Solute Concentration Level in Simulated Body Fluids

Abstract

An improved design topology comprising of a modified CSRR based air-via incorporated structure is proposed to determine solute concentration variations in Simulated Body Fluids (SBF). The proposed sensor has circular aligned vias surrounding the sensing region for high E-field confinement minimizing field scattering near the sensing area. The sensor can sense liquid samples having permittivity ($\varepsilon_{\mathrm{r}}$) up to the dielectric of blood and blood plasma very comparable to SBF with improved characterization for high loss samples. Placing a sample through a 1.5mm fluidic channel within the substrate increases the interaction with field confined within the sensing structure and helps determine loss content in sample with higher accuracy. The sensor is fabricated on Rogers 6002 ($\varepsilon_{\mathrm{r}}=2.2$) having a thickness 3.75 mm so that a flexible tube of 1.5mm can be placed across the sensing region and simulated using CST MWS. The measured result indicates a percentage variation of 3.5dB/gm of NaCl in SBF.