Temperature measurements in microfluidic systems: heat dissipation of negative dielectrophoresis barriers.
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.
Seger-Sauli
Urban
U
Microsystems Laboratory, Lausanne, Switzerland. urban.seger@epfl.ch
Panayiotou
Marilia
M
Schnydrig
Silvan
S
Jordan
Martin
M
Renaud
Philippe
P
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
D015335:Molecular Probes