Victoria University

Advancement of Measurement Techniques for Tunable Resistive Pulse Sensing

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dc.contributor.advisor Willmott, Geoff
dc.contributor.advisor Hodgkiss, Justin Weatherall, Eva 2017-08-16T00:59:20Z 2017-08-16T00:59:20Z 2017 2017
dc.description.abstract Tunable resistive pulse sensing (TRPS) is a particle-by-particle analysis technique combining the Coulter principle with size-tunable pores. TRPS can be used to characterize biological and synthetic particles 50 nm - 20 µm in diameter. Information is obtained from the resistive pulse signal, a transient change in ionic current observed when a particle passes through the pore. TRPS has been shown to provide excellent resolution and accuracy for measuring particle size and concentration as well as providing information about particle charge. TRPS is therefore applicable to many industrial and fundamental research areas involving aptamers, drug delivery particles, extracellular vesicles and other biological particle types. Advancement of this technology requires a better understanding of the technique, particularly in the area of particle surface charge measurement and this Thesis helps to provide that understanding. In this work, firstly particle ζ-potential measurement using TRPS was investigated. A number of different measurement methods are presented and the uncertainties associated with each method are outlined. The ζ-potential for a variety of particles with different surface charges were measured in a range of electrolytes. Particle ζ-potential measurements were then improved upon with the addition of streaming potential measurements to measure the pore surface charge. The ζ-potential of the pore surface, which makes a significant contribution to particle ζ-potential calculations, was measured using a set up which works alongside the qNano. Streaming potential measurements were also used to investigate changes in the pore surface charge following application of number of different chemical coatings. The volume of data collected and detail of analysis in this work (including uncertainties) is unprecedented in TRPS ζ potential measurements. Biphasic pulses arising from the charge on the particles were investigated. The pulse is conventionally resistive, but biphasic pulses which include both resistive and conductive components are significant for less than 50 mM salt concentrations when measuring 200 nm particles. The experimental variables investigated include the concentration of the electrolyte, particle charge, pore size, applied voltage, and the direction of particlemotion. Conductive pulse size was seen to decrease with increasing electrolyte concentration and pore size and increase with applied voltage. A linear relationship was found between conductive pulse magnitude and particle surface group density. The influence of direction of motion on conductive pulses was consistent with concentration polarization of an ion selective pore. Biphasic pulses were also seen to affect conventional TRPS particle size measurements. Finally, size distribution broadening due to varying particle trajectories was investigated. Pulse size distributions for monodisperse particles became broader when the pore size was increased and featured two distinct peaks. Relatively large pulses are produced by particles with trajectories passing near to the edge of the pore. Other experiments determined that pulse size distributions are independent of applied voltage but broaden with increasing pressure applied across the membrane. en_NZ
dc.language.iso en_NZ
dc.publisher Victoria University of Wellington en_NZ
dc.subject Tunable resistive pulse sensing en_NZ
dc.subject Nanoparticle en_NZ
dc.subject Zeta potential en_NZ
dc.subject Size en_NZ
dc.subject Charge en_NZ
dc.title Advancement of Measurement Techniques for Tunable Resistive Pulse Sensing en_NZ
dc.type text en_NZ
vuwschema.contributor.unit School of Chemical and Physical Sciences en_NZ
vuwschema.contributor.unit Macdiarmid Institute for Advanced Materials and Nanotechnology en_NZ
vuwschema.type.vuw Awarded Doctoral Thesis en_NZ Chemistry en_NZ Victoria University of Wellington en_NZ Doctoral en_NZ Doctor of Philosophy en_NZ
dc.rights.license Author Retains Copyright en_NZ 2017-03-23T09:04:04Z
vuwschema.subject.anzsrcfor 030603 Colloid and Surface Chemistry en_NZ
vuwschema.subject.anzsrcfor 030199 Analytical Chemistry not elsewhere classified en_NZ
vuwschema.subject.anzsrcseo 970103 Expanding Knowledge in the Chemical Sciences en_NZ
vuwschema.subject.anzsrcseo 970102 Expanding Knowledge in the Physical Sciences en_NZ
vuwschema.subject.anzsrctoa 4 EXPERIMENTAL DEVELOPMENT en_NZ

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