DEVELOPMENT OF ACCELERATED BACTERIAL COLLECTION AND DETECTION (ABCD) PLATFORMS USING AC ELECTROKINETICS
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Authors
Fathy, Jino
Date
Type
thesis
Language
eng
Keyword
MEMS, AC Electrokinetics, Biosensor, Microconcentrator, Microcantilever
Alternative Title
Abstract
Real-time detection of low concentrations of bacteria is essential in health and environmental
monitoring, and biosensors are promising tools for this. However, the limited number of analytes
and the time required for diffusion and Brownian motion to transport them to the sensing surface
highlight the importance of using particle concentration. Particle concentration could be done
during the pre-sensing sample preparation and/or by accelerating the analytes' movement towards
the sensing surface and locally concentrating them there. In this thesis, individual components were
designed and developed based on AC electrokinetics for both pre-sensing and local concentration
of particles. Particles were concentrated inside microchannels as pre-sensing particle enrichment
in two designed platforms. A coil embedded in a PDMS channel is one novel design. Particles are
pushed to the centre of the channel by dielectrophoresis force when electric potentials are applied
to the wires that make up the coil. The other design consists of two coplanar asymmetric electrodes
on the walls of a microchannel, and a floating potential electrode is placed at the bottom of the
channel. By using AC electrothermal and dielectrophoresis effects, this design concentrates the
particles in the channel's centre. Furthermore, gap method microcantilever biosensors were used to
detect E. coli and P. aeruginosa bacteria in water in real time and with high sensitivity. In this
method, a fixed structure connected to an AC signal is placed near the free end of a vibrating
microcantilever that is grounded. We developed this technique by making longer and thinner gaps
between the free end of the cantilever and the fixed structure. The goal was to expand the area
where dielectrophoresis is effective and to strengthen this force by making the gap thinner. Based
on this, two designs were created: a V-shaped and a rectangular microcantilever. In this thesis,
detection of 10 cells/mL was achieved in a 7-min period. The developed microcantilever biosensors
offer real-time, sensitive, low-noise, and repeatable biosensing with a very low limit of detection
(1–9 cells/mL). Moreover, experiments investigated functionalizing the gap method
microcantilever biosensor's surface to enhance specificity.
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Copying and Preserving Your Thesis
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.