Date of Graduation

8-2025

Document Type

Thesis

Degree Name

Master of Science in Biological Engineering (MS)

Degree Level

Graduate

Department

Biological and Agricultural Engineering

Advisor/Mentor

Edwards, Martin

Committee Member

Li, Jiali

Second Committee Member

Ware, Morgan

Third Committee Member

Ranil Wickramasinghe, Ranil

Keywords

Finite Element Modeling; Glass Nanopore; Nanoparticle; Polymer enhanced; Resistive Pulse Sensing

Abstract

The resistive pulse technique characterizes single analytes by detecting fluctuations in the ion current as they pass through a narrow orifice connecting two electrolyte-filled chambers, each containing a single electrode. The amplitude, shape, frequency, and duration of these fluctuations primarily provide information about the analyte’s size, shape, concentration, and net surface charge, respectively. One configuration for resistive pulse measurements is of an electrolyte-filled nanopipette immersed in a bath, where the nanopipette tip acts as the nanoscale orifice. It was previously shown that incorporating the large quantities polymer polyethylene glycol (PEG 8K, 50% w/v) into the external electrolyte bath dramatically enhanced the current deviations for analytes translocating out of the pipette compared to identical conditions without the PEG (0.1 M KCl in both the bath and pipette, same pipette geometry). This work presents a configuration where a PEG-electrolyte solution is confined within a nanopipette and the analyte in the external bath. A numerical model was developed to simulate the electrical response of the glass nanopore system, providing insights into the mechanisms of signal enhancement. This setup retains PEG-induced signal enhancement and offers advantages for sensing applications where adding PEG to the sample is impractical or disruptive. Additionally, a single nanopipette sensor can characterize multiple samples, such as those in a 96-well plate. This approach also enables the parallelization of nanopipette measurements with complementary electrochemical analyses, improving experimental efficiency.

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