Split-Ring Resonator Based Microwave Microfluidic Biosensor for Single Bioparticle Position Location and Live/Dead Cell Differentiation

Abstract

This paper presents a novel microwave biosensor integrated with a microfluidic platform for the label-free detection and differentiation of biological particles, including live and dead Escherichia coli (E. coli). The sensor is based on a 50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Omega$</tex-math></inline-formula> microstrip line coupled to an annular split-ring resonator (SRR), designed and fabricated for a high sensitivity response to changes in the dielectric properties on the bioparticle. The integration with a microfluidic channel allows precise control and delivery of biological samples to the sensing region. Experiments demonstrated the sensor’s ability to detect individual microbeads and distinguish between single live and dead bacterial cells through measurable shifts in resonance frequency. Furthermore, by applying an Inverse Fast Fourier Transform (IFFT) to the differential transmission parameter, the system enables the spatial localization of single particles within the microfluidic channel. The results indicate significant potential for point-of-care diagnostics and environmental monitoring applications, highlighting the advantages of microwave biosensing for real-time, single-particle analysis.