Dielectric Detection of Single Nanoparticles Using a Microwave Resonator Integrated with a Nanopore

TL;DR

This paper introduces a microwave resonator-based impedimetric sensor integrated with a nanopore for detecting single nanoparticles by measuring dielectric responses, offering a complementary method to traditional resistive pulse sensing.

Contribution

The work presents a novel impedance sensing approach using a microwave resonator with a nanopore to detect dielectric signatures of individual nanoparticles.

Findings

Successfully detected 50 nm and 100 nm polystyrene nanoparticles

Impedance changes correlated with nanoparticle translocation events

Method provides dielectric characterization as an alternative to ionic current measurements

Abstract

The characterization of individual nanoparticles in a liquid constitutes a critical challenge for environmental, material, and biological sciences. To detect nanoparticles, electronic approaches are especially desirable owing to their compactness and lower costs. Indeed, for single-molecule and single-nanoparticle detection, resistive pulse sensing has advanced significantly during the last two decades. While resistive pulse sensing was widely used to obtain the geometric size information, impedimetric measurements to obtain dielectric signatures of nanoparticles have scarcely been reported. To explore this orthogonal sensing modality, we developed an impedimetric sensor based on a microwave resonator with a nanoscale sensing gap surrounding a nanopore. The approach of single nanoparticles near the sensing region and their translocation through the nanopore induced sudden changes in the impedance of the structure. The impedance changes in turn were picked up by the phase response of the microwave resonator. We worked with 100 nm and 50 nm polystyrene nanoparticles to observe single-particle events. Our current implementation was limited by the non-uniform electric field at the sensing region. The work provides a complementary sensing modality for nanoparticle characterization where the dielectric response, rather than the ionic current, determines the signal.