title: Pulse Size Distributions in Tunable Resistive Pulse Sensing.
abstract: The use of resistive pulse sensors for submicron particle size measurements relies on a clear understanding of pulse size distributions. Here, broadening of such distributions has been studied and explained using conical pores and nominally monodisperse polystyrene particles 200-800 nm in diameter. The use of tunable resistive pulse sensing (TRPS) enabled continuous in situ control of the pore size during experiments. Pulse size distributions became broader when the pore size was increased and featured two distinct peaks. Similar distributions were generated using finite element simulations, which suggested that 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. The applied pressure could also be reversed in response to a pulse, which enabled repeated measurement of individual particles moving back and forth through the pore. Hydrodynamic and electrophoretic focusing each appear to affect particle trajectories under certain conditions.
authors.forename: Eva
authors.initials: E
authors.lastname: Weatherall
authors.forename: Peter
authors.initials: P
authors.lastname: Hauer
authors.affiliation: Izon Science Limited, 8C Homersham Place, P.O. Box 39168, Burnside, Christchurch 8053, New Zealand.|School of Mathematics and Physics, The University of Queensland , Brisbane 4072, Australia.
authors.forename: Robert
authors.initials: R
authors.lastname: Vogel
authors.affiliation: The Departments of Physics and Chemistry, The University of Auckland , Auckland 1142, New Zealand.
authors.forename: Geoff R
authors.initials: GR
authors.lastname: Willmott