title: Temperature measurements in microfluidic systems: heat dissipation of negative dielectrophoresis barriers.
abstract: The manipulation of living biological cells in microfluidic channels by a combination of negative dielectrophoretic barriers and pressure-driven flows is widely employed in lab-on-a-chip systems. However, electric fields in conducting media induce Joule heating. This study investigates if the local temperatures reached under typical experimental conditions in miniaturized systems cause a potential risk for hyperthermic stress or cell damage. Two methods of optical in situ temperature detection have been tested and compared: (i) the exposure of the thermo-dependent fluorescent dye Rhodamine B to heat sources situated in microfluidic channels, and (ii) the use of thermoprecipitating N-alkyl-substituted acrylamide polymers as temperature threshold probes. Two-dimensional images of temperature distributions in the vicinity of active negative dielectrophoresis (nDEP)-barriers have been obtained and local temperature variations of more than 20 degrees C have been observed at the electrode edges. Heat propagation via both buffer and channel walls lead to significant temperature increases within a perimeter of 100 microm and more. These data indicate that power dissipation has to be taken into account when experiments at physiological temperatures are planned.
authors.affiliation: Microsystems Laboratory, Lausanne, Switzerland. urban.seger@epfl.ch
authors.forename: Urban
authors.initials: U
authors.lastname: Seger-Sauli
authors.forename: Marilia
authors.initials: M
authors.lastname: Panayiotou
authors.forename: Silvan
authors.initials: S
authors.lastname: Schnydrig
authors.forename: Martin
authors.initials: M
authors.lastname: Jordan
authors.forename: Philippe
authors.initials: P
authors.lastname: Renaud
mesh_terms: D002468:Cell Physiological Phenomena; D002477:Cells; D046209:Electrophoresis, Microchip / Q000295:instrumentation* / Q000379:methods; D006358:Hot Temperature; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D015335:Molecular Probes; D013696:Temperature
chemical_list: D015335:Molecular Probes