Design and Characterization of a Sensorized Microfluidic Cell-Culture System with Electro-Thermal Micro-Pumps and Sensors for Cell Adhesion, Oxygen, and pH on a Glass Chip.
We combined a multi-sensor glass-chip with a microfluidic channel grid for the characterization of cellular behavior. The grid was imprinted in poly-dimethyl-siloxane. Mouse-embryonal/fetal calvaria fibroblasts (MC3T3-E1) were used as a model system. Thin-film platinum (Pt) sensors for respiration (amperometric oxygen electrode), acidification (potentiometric pH electrodes) and cell adhesion (interdigitated-electrodes structures, IDES) allowed us to monitor cell-physiological parameters as well as the cell-spreading behavior. Two on-chip electro-thermal micro-pumps (ETμPs) permitted the induction of medium flow in the system, e.g., for medium mixing and drug delivery. The glass-wafer technology ensured the microscopic observability of the on-chip cell culture. Connecting Pt structures were passivated by a 1.2 μm layer of silicon nitride (Si3N4). Thin Si3N4 layers (20 nm or 60 nm) were used as the sensitive material of the pH electrodes. These electrodes showed a linear behavior in the pH range from 4 to 9, with a sensitivity of up to 39 mV per pH step. The oxygen sensors were circular Pt electrodes with a sensor area of 78.5 μm(2). Their sensitivity was 100 pA per 1% oxygen increase in the range from 0% to 21% oxygen (air saturated). Two different IDES geometries with 30- and 50-μm finger spacings showed comparable sensitivities in detecting the proliferation rate of MC3T3 cells. These cells were cultured for 11 days in vitro to test the biocompatibility, microfluidics and electric sensors of our system under standard laboratory conditions.
Chair for Biophysics, Department of Biology, University of Rostock, Gertrudenstr. 11a, 18057 Rostock, Germany. sebastian.bonk@uni-rostock.de.
Sebastian M
SM
Bonk
Chair for Biophysics, Department of Biology, University of Rostock, Gertrudenstr. 11a, 18057 Rostock, Germany. marco.stubbe@uni-rostock.de.
Marco
M
Stubbe
Leibniz Institute for Farm Animal Biology, Institute of Muscle Biology and Growth, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany. buehler@fbn-dummerstorf.de.
Sebastian M
SM
Buehler
Chair for Biophysics, Department of Biology, University of Rostock, Gertrudenstr. 11a, 18057 Rostock, Germany. carsten.tautorat@uni-rostock.de.
Carsten
C
Tautorat
Chair for Biophysics, Department of Biology, University of Rostock, Gertrudenstr. 11a, 18057 Rostock, Germany. werner.baumann@uni-rostock.de.
Werner
W
Baumann
DOT GmbH, Charles-Darwin-Ring 1A, 18059 Rostock, Germany. klinkenberg@dot-coating.de.
Ernst-Dieter
ED
Klinkenberg
Chair for Biophysics, Department of Biology, University of Rostock, Gertrudenstr. 11a, 18057 Rostock, Germany. jan.gimsa@uni-rostock.de.
Jan
J
Gimsa
D000818:Animals; D015374:Biosensing Techniques; D002448:Cell Adhesion; D018929:Cell Culture Techniques; D004566:Electrodes; D005347:Fibroblasts; D006863:Hydrogen-Ion Concentration; D056656:Lab-On-A-Chip Devices; D051379:Mice; D044085:Microfluidics / Q000295:instrumentation / Q000379:methods*; D010101:Oxygen Consumption
acidification; bone cells; lab-on chip; respiration; thin film platinum sensors