Versatile usage of liquid metals in emerging microwave technologies

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Liquid Metal

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This research is comprised of two distinct, but related projects. KU Leuven is the home institution for one project and the University of Melbourne will host the second.

KU Leuven-based project:

Self‐healing flexible biosensors for microwave dielectric spectroscopy

Over the past decades, flexible materials featuring characteristics such as miniaturization, outstanding mechanical flexibility (soft and deformable), excellent loss tangent, stable and desirable electrical properties over wide frequency bandwidths, biocompatibility and real‐time detection have attracted increasing attention in various applications.

With this trend, attempts to combine flexible materials with electromagnetic technology have also been reported in recent years in the microwave community, leading to hundreds of flexible electronics and systems, including antennas and passive circuits.

Though novel, microwave sensing is a rapidly developing technology that has been used for healthcare applications like solution concentrations, glucose monitoring in diabetic patients and non‐invasive body fluids monitoring. However, the majority of microwave biosensors developed to date are based on rigid substrates, and studies and publications on flexible microwave biosensors are still in their infancy.

To enhance characterisations in bio‐incubators and/or well plates, it is essential to investigate additive manufacturing techniques to achieve flexible, though robust biosensors.

The approach envisioned in this project is metal printing on a flexible material with very good microwave properties, such as PDMS. As micro‐cracks may occur during bending, self‐healing techniques using Galinstan will be investigated.

The challenge is not only to design such a robust flexible microwave sensor, but also to ensure its inertness with respect to water based biological samples. To improve the diagnosis accuracy, a temperature sensor would also be embedded in the biosensor.

This project builds on the complementary expertise on microwave biosensor design and dielectric spectroscopy at KU Leuven, and the knowledge on additive manufacturing techniques at the University of Melbourne.

Project aims:

  • To design passive biosensors for microwave dielectric spectroscopy that can both tolerate and heal damage caused by flexing and variation to geometry such as cracks
  • To create a robust and repeatable sensor technology, including a well‐defined and reliable interface with the material under test
  • To monitor the temperature of microfluidic biological samples in an accurate and inexpensive way
Graduate researcher: Benyamin Harkinezhad

Supervision team (Leuven)

Principal Investigators (PIs):

Professor Dr Dominique Schreurs (KU Leuven)
Professor Stan Skafidas (The University of Melbourne)

Co-Principal Investigators (co-PIs)

Professor Dr Bart Nauwelaers (KU Leuven)
Professor Robin Evans (The University of Melbourne)

Melbourne-based project:

LTCC‐based liquid metal tunable high‐Q notch filters for the emerging 5G communication systems

Project aims:

The current approaches for the implementation of tunable high‐Q notch filters fail to concurrently address the compact size, high‐Q and strong attenuation, and frequency tunability challenges.

This research project aims to investigate and design a compact and tunable/reconfigurable notch filter using LTCC (Low-Temperature Co‐fired Ceramic) fabrication technology and liquid metals for 5G applications.

5G transceivers will be required to support a large number of applications with diverse requirements in terms of frequency and bandwidth. These requirements necessitate multi‐standard and multi‐band communication systems with tuning and reconfiguration capabilities.

The proposed filter will be based on these requirements and will be integrated with other microwave devices in the transceiver. Existing techniques of implementing a notch filter are either bulky, have a high insertion loss or lack high attenuation within the stopband of the filter.

The LTTC fabrication technique will provide a compact filter with very high‐Q, achieving low loss and strong attenuation in the frequency band of interest where the rejection of interfering signal is an essential part of the transceiver.

The filter can be tuned or reconfigured by utilising a liquid metal, such as Galinstan, in microchannels. Initially, a high‐Q resonator with a fast tuning/reconfiguring response will be investigated, and then a high order filter will be designed based on the initial resonator.

This research builds on the complementary expertise on fabrication using LTCC technology and liquid metals at the University of Melbourne, and the knowledge on (tunable/reconfigurable) filter modelling at KU Leuven.

Project aims:

  1. To investigate and model various resonator topologies to produce high‐Q and strong in‐band attenuation using liquid metals;
  2. To explore possible solutions to achieve a fast tunable/reconfigurable notch filter using liquid metals and LTCC (Low-Temperature Co‐fired Ceramic) technology;
  3. To analyse and model a high order tunable/reconfigurable filter using liquid metal with minimum insertion loss.
Graduate researcher: Abbas Karimi

Supervision team (Melbourne)

Principal Investigators (PIs):

Professor Stan Skafidas (The University of Melbourne)
Professor Dr Dominique Schreurs (KU Leuven)

Co-Principal Investigators (co-PIs)

Professor Robin Evans (The University of Melbourne)
Professor Dr Bart Nauwelaers (KU Leuven)

Other joint PhD projects