title: Low-power concentration and separation using temperature gradient focusing via Joule heating.
abstract: We present an experimental study of temperature gradient focusing (TGF) exploiting an inherent Joule heating phenomenon. A simple variable-width PDMS device delivers rapid and repeatable focusing of model analytes using significantly lower power than conventional TGF techniques. High electric potential applied to the device induces a temperature gradient within the microchannel due to the channel's variable width, and the temperature-dependent mobility of the analytes causes focusing at a specific location. The PDMS device also shows simultaneous separation and concentration capability of a mixture of two sample analytes in less than 10 min. An experiment combining Joule heating with external heating/cooling further supports the hypothesis that temperature is indeed the dominant factor in achieving focusing with this technique.
authors.affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109-2125, USA. sunmk@umich.edu
authors.forename: Sun Min
authors.initials: SM
authors.lastname: Kim
authors.forename: Greg J
authors.initials: GJ
authors.lastname: Sommer
authors.forename: Mark A
authors.initials: MA
authors.lastname: Burns
authors.forename: Ernest F
authors.initials: EF
authors.lastname: Hasselbrink
mesh_terms: D019793:Fluorescein / Q000032:analysis / Q000737:chemistry; D013696:Temperature
chemical_list: D019793:Fluorescein