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Figure 1
Impedance measurement setup: A) Microelectrode array chip with 12 IDEs; B) zoom-in view of one IDE (the ca. 500 μm x 500 μm opening in the silicon nitride passivation layer appears as a lighter region in the center) ; C) chip holder (the lower plate accommodates a MEA chip and the upper plate provides the 600 μl cell culture chamber and an array of holes for electrical connections using spring-loaded pins; fluid tight sealing on the MEA chip is achieved by using a laser cut silicon rubber gasket); D) Printed circuit board (PCB) of the custom-made 12-channel bipotentiostat (the PCB has an opening to the cell culture vial of the chip holder to allow liquid handling and microscopic visualization; E) user interface of the data acquisition software showing recorded impedance magnitude vs. log frequency.
Figure 2
Cell Index vs. time for LUHMES cells: Initial cell density (cells/cm2) A) 30,000; B) 60,000; C) 120,000. Proliferating (blue) and differentiating (red) cells. Time in days after cell seeding. (Error bars: s.e.m., n = 6).
Figure 3
Fluorescence microscopy images of live stained (Calcein AM) LUHMES cells in growth medium (GM) and differentiation medium (DM). Initial cell density 60,000 cells/cm2. Time in days after cell seeding. (Scale bars: 50 μm).
Figure 4
Cell Index vs. time for hVM1 Bcl-XL cells: Initial cell density 120,000 cells/cm2. Proliferating (blue) and differentiating (red) cells. Time in days after cell seeding. (Error bars: s.e.m., n = 6).
Figure 5
Fluorescence microscopy images of live stained (Calcein AM) hVM1 Bcl-XL cells in growth medium (GM) and differentiation medium (DM). Initial cell density 120,000 cells/cm2. Time in days after cell seeding. (Scale bars: 50 μm)
Figure 6
Equivalent circuit models for analysis of impedance spectra acquired A) in the presence and B) in the absence of cells. (Cell specific parameters: Rextra, Rcell, Ccell). For detailed description of the components, see the text.
Figure 7
Example of typical Bode plots for an electrode and the same electrode 48 h after seeding of 60,000 LUHMES cells/cm2: A) impedance magnitude and B) phase angle. Solid lines show the nonlinear least squares fit of the experimental data to the equivalent circuit models of Fig. 6.
Figure 8
Summary of the cell specific equivalent circuit components (Rcell, Rextra, Ccell) for A) proliferating and B) differentiating LUHMES cells (seeding density: 60,000 cells/cm2). Time in days after cell seeding. (Error bars: s.e.m., n = 6).
Figure 9
Summary of the cell specific equivalent circuit components (Rcell, Rextra, Ccell) for A) proliferating and B) differentiating hVM1 Bcl-XL cells (seeding density: 120,000 cells/cm2). Time in days after cell seeding. (Error bars: s.e.m., n = 6).
Figure S1
Normalized impedance vs. frequency for A) LUHMES (60,000 cells/cm2) and B) hVM1 Bcl-XL (120,000 cells/cm2). The spectra were acquired 48 h after cell seeding. (Error bars: standard deviation, n = 3)
Figure S2
Cell Index vs. time for proliferating hVM1 Bcl-XL cells. Initial cell seeding density 60,000 cells/cm2 and 120,000 cells/cm2. (Error bars: standard deviation, n = 3)
