Ion concentration polarization at a packed bed of microbeads for high-throughput preconcentration and label-free electrochemical detection of charged analytes
Date
2024-08
Authors
Peramune, Umesha
Major Professor
Advisor
Anand, Robbyn
Smith, Emily
Anderson, Jared
Gundlach-Graham, Alexander
Claussen, Jonathan
Committee Member
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Abstract
The development of microfluidics and miniaturized electronics has tuned a new era in analytical chemistry, biomedical engineering, disease diagnosis and environmental science. Owing to the advantages of microfluidics, it has the potential to bring some of the analytical applications of a centralized laboratory to low resource settings. However, as in any other analytical workflow, sample preparation step is the bottle neck of microfluidics. This step becomes even more significant when dealing with small sample volumes where the matrix effects are high, and the target concentration is low.
The work presented in this dissertation is based on two closely related electrokinetic focusing techniques known as ion concentration polarization focusing (ICPF) and faradaic ion concentration polarization focusing (fICPF). These phenomena can be incorporated in microfluidic analytical devices for preconcentration and separation of charged analytes prior to their detection. Despite the numerous fundamental studies and applied research on ICP and fICP, improving the volumetric throughput remains a critical challenge in ICP-based applications. The objective of this dissertation is to address this challenge by incorporating microbead beds to generate a more stable concentration polarization layer with less fluidic instabilities.
This dissertation describes how fICP is harnessed to increase the detection sensitivity of nucleic acids by stable focusing on a bioconjugated bead bed and their subsequent label-free detection on the same chip by probing ion-transport modulation. Secondly, how this packed bed approach was transferred to a 3D-printed millifluidic chip used to achieve high volumetric throughput preconcentration using 1) conductive beads and a cationic buffer to drive fICP, and 2) commercially available cation-exchange resin to drive ICP is presented.
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dissertation