Self‐healing flexible biosensors for microwave dielectric spectroscopy

This joint PhD project is based at KU Leuven with a minimum 12 month stay at The University of Melbourne.

Project title:  Versatile usage of liquid metals in emerging microwave technologies

Project description
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, being biocompatible, usable for real‐time detection, etc., 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 which has been used for healthcare applications like solution concentrations, glucose monitoring in diabetic patients [1], non‐invasive body fluids monitoring [2], etc. 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.

Microwave microfluidic sensors are emerging as an inexpensive and portable diagnosis tool compared to the conventional and bulky optical techniques. The feasibility of microwave dielectric spectroscopy has been shown already but the reported biosensors were implemented on rigid microwave substrates, limiting the types of samples that can be measured. To enhance characterizations in bio‐incubators and/or well plates, it is essential to investigate additive manufacturing techniques to achieve flexible though robust biosensors.

Research objectives
The research objectives are three‐fold:

  1. To design passive biosensors for microwave dielectric spectroscopy that can both tolerate and heal to damage caused by flexing and variation to geometry such as cracks;
  2. To create a robust and repeatable sensor technology, incl. a well‐defined and reliable interface with the material under test;
  3. To monitor the temperature of microfluidic bio samples in an accurate and inexpensive way.

The approach envisioned 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, also a temperature sensor is to be embedded in the biosensor.

This PhD research 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.

The project will be complemented by the project on LTCC‐based liquid metal tunable high‐Q notch filters for the emerging 5G communication and the collaboration will ensure a successful completion of the project

Supervision team:

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)