Method of electrically measuring the electrical properties of individual particles flowing in a liquid

Abstract

A method of electrically measuring the electrical properties of individual particles flowing in a liquid, which method comprises: (i) providing apparatus () which is for electrically measuring the individual particles and which has: (a) a fluidic channel () for receiving a liquid () having the individual particles () in suspension in the liquid (); (b) a first electrode arrangement () having at least one measurement electrode () and at least one signal electrode (); and (c) at least one other electrode arrangement () having at least one measurement electrode () and at least one signal electrode (); (ii) providing a flow of the liquid () through the fluidic channel (); (iii) applying a first electrical signal through the liquid () and along a first conduction path between the measurement electrode () and the signal electrode () of the first electrode arrangement (); (iv) applying an electrical signal through the liquid () and along at least one other conduction path; (v) comparing the electrical signal between the first and the other conduction paths to generate a comparison signal; (vi) detecting an individual particle passing through the apparatus () by detecting a feature of the comparison signal of the individual particle, and obtaining at least one output waveform; (vii) measuring a height-related feature of the output waveform of the individual particle, and generating a first order assessment of the electrical properties of the individual particle; and (viii) assessing the shape of the output waveform to perform a second order adjustment to the first order assessment of the electrical properties of the individual particle, with the second order adjustment utilising data on a perceived degree of error in the first order assessment based on information on a known relationship between the waveform shape and the error in the first order assessment.