Millimeter-wave sensor based on a λ/2-line resonator for identification and dielectric characterization of non-ionic surfactants.

H Rodilla,J Vukusic,G D M Jeffries,J Stake,A Jesorka,A A Kim

doi:10.1038/srep19523

H Rodilla, J Vukusic + Show 4 more

Open Access

https://doi.org/10.1038/srep19523

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Abstract

Studies of biological and artificial membrane systems, such as niosomes, currently rely on the use of fluorescent tags, which can influence the system under investigation. For this reason, the development of label-free, non-invasive detection techniques is of great interest. We demonstrate an open-volume label-free millimeter-wave sensing platform based on a coplanar waveguide, developed for identification and characterization of niosome constituents. A design based on a λ/2-line resonator was used and on-wafer measurements of transmission and reflection parameters were performed up to 110 GHz. Our sensor was able to clearly distinguish between common niosome constituents, non-ionic surfactants Tween 20 and Span 80, measuring a resonance shift of 3 GHz between them. The complex permittivities of the molecular compounds have been extracted. Our results indicate insignificant frequency dependence in the investigated frequency range (3 GHz – 110 GHz). Values of permittivity around 3.0 + 0.7i and 2.2 + 0.4i were obtained for Tween 20 and Span 80, respectively.

Highlights

In order to improve the selectivity of the sensor, a λ /2-line resonator was designed
Permittivity values of the molecular compounds under study have been obtained by modifying the permittivity of the material on top of the sensor in the circuit model, to reproduce the experimental results
In this work we demonstrate an open-volume sensing platform for identification and characterizing non-ionic surfactants in the millimeter-wave frequency range based on a λ /2-line resonator

Summary

Introduction

The experimental results were obtained by on-wafer S-parameter measurements (phase and magnitude of the transmitted (S21), and reflected (S11) power), from 10 MHz to 110 GHz with the reference plane at the probe tips. In order to minimize the experimentally observed substrate modes (a typical finding at this frequency range), a doped Si wafer was located underneath our glass substrate[14].

Results

Conclusion