Microwave microfluidic resonant sensors and applicators

Hamzah, Hayder Miri 2017. Microwave microfluidic resonant sensors and applicators. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Microwave sensors and applicators are of major interest in applications where no physical contact is possible or the use of active devices is impractical. Microwave sensors offer numerous advantages compared to traditional techniques, not least in terms of convenience and speed, since they do not require any markers. Furthermore, such microwave sensor methods can be designed to be fully compatible with lab-on-a-chip approaches. In this work, the interaction between the microwave electric field and a microfluidic dielectric sample using resonant microwave sensors has been studied, and therefore the dielectric constant for sample materials can be measured by using perturbation theory when the sample is placed in the electric field. Two forms of novel resonator for microfluidic sensing are proposed: a re-entrant microwave cavity (RMC) and split-ring resonator (SRR). The RMC is one of the most useful forms of cavity for this purpose due to its simple geometry, wide frequency range tuning and high quality factor. It has been designed, machined, and evaluated experimentally with common liquids and different mixtures based on water and dielectric microspheres, in both static and flow situations. Furthermore, we present a new approach for microfluidic sensing and microfluidic heating using a novel split ring resonator (SRR) for high sensing sensitivity and efficient heating of lossy dielectrics. The designed SRR shows very good performance experimentally in microfluidic sensing (pure liquids, chemical solutions, and saline concentration level), as well as in microfluidic heating where it is demonstrated how nearly all the microwave power is delivered to the sample under test. Owing to its compact size and high efficiency, the SRR has been utilized in an important microbiological applications for rapid DNA release using low power levels (< 1 W). It is envisaged that this system is now suitable for incorporation within a rapid, hand-held, point-of-care detector for bacterial infections such as Clostridium difficile.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Engineering
Uncontrolled Keywords:	Microwave resonant sensors and applicators; Microfluidic sensing using microwave sensors; Microwave split ring resonator SRR; Microwave cavity and re-entrant cavity; Healthcare applications using microwave technology.
Date of First Compliant Deposit:	31 July 2017
Last Modified:	20 Apr 2021 13:48
URI:	https://orca.cardiff.ac.uk/id/eprint/102993

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