title: Bacteria counting with impedance spectroscopy in a micro probe station.
abstract: A method to quantify the density of viable biological cells in suspensions is presented. The method is implemented by low-frequency impedance spectroscopy and based on the finding that immobilized ions are released to move freely in the surrounding suspension when viable Escherichia coli cells are killed by a heat shock. The presented results show that an amount of ions corresponding to approximately 2 x 10(8) unit charges are released per viable bacterium killed. A micro probe station with coplanar Ti electrodes was electrically characterized and used as a measuring unit for the impedance spectroscopy recordings. This unit is compatible with common microfabrication techniques and should enable the presented method to be employed using a flow-cell device for viable bacteria counting in miniaturized on-line monitoring systems.
authors.affiliation: Department of Engineering Sciences, The Angström Laboratory, Uppsala University, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Jönsson
authors.forename: Ken
authors.initials: K
authors.lastname: Welch
authors.forename: Sven
authors.initials: S
authors.lastname: Hamp
authors.forename: Maria
authors.initials: M
authors.lastname: Strømme
mesh_terms: D000465:Algorithms; D015169:Colony Count, Microbial / Q000295:instrumentation* / Q000379:methods*; D003720:Densitometry; D004553:Electric Conductivity; D004566:Electrodes; D004926:Escherichia coli; D009862:Online Systems; D013057:Spectrum Analysis / Q000295:instrumentation* / Q000379:methods*