Spatially Resolved Sensing in Microfluidics with Multimode Microwave Resonators

TL;DR

This paper adapts multimode resonance techniques from mechanical sensors to microwave resonators in microfluidics, enabling spatial resolution, sizing, and imaging of analytes through electromagnetic field sensing.

Contribution

It introduces a novel application of multimode resonance for spatially resolved sensing in microwave microfluidic devices, expanding capabilities beyond simple detection.

Findings

Higher-order modes provide spatial, size, and position data.

Potential for image reconstruction with multiple modes.

Achieved sizing and imaging of analytes via impedance spectroscopy.

Abstract

The analogy between mechanical and electromagnetic resonators has been a celebrated paradigm of science and engineering. Exploration of this analogy in recent years has resulted in several exciting research directions, including cavity optomechanics[1], phononic bandgap materials[2] and phononic metamaterials[3-5]. In these examples, progress in electromagnetic research has usually led the way for their mechanical counterparts. Here, we contribute to this analogy from a different perspective by adapting a sensing technique originally developed for mechanical devices to increase the capabilities of sensors based on electromagnetic fields. More specifically, multimode resonance techniques, which enable spatial resolution in inertial mass sensing experiments with nanoelectromechanical systems (NEMS), are tailored for use in microwave resonant sensing, which is commonly employed in microfluidics. We show that the use of higher-order modes of such sensors can provide electrical volume, position and geometric size data. The combination of such spatial features implies the potential for image reconstruction when a large number of modes are used. With the analytical and experimental framework presented here, we can move beyond simple counting and achieve the sizing and imaging of analytes with impedance spectroscopy.