Fig. 1

Electrical stimulation setup. A Bottom view of electrode lid (Mobini chamber) in a standard 6-well-plate. B Schematic view of Mobini chamber electrode setup and wiring. The symbols with lightning bolt indicate electrical stimulation of cells (red) or cell-free medium (yellow). In the parallel control approach no current was applied (symbols without lightning). C View of the stimulation setup with 1) Mobini chamber, 2) incubator, 3) circuit board, 4) power supply, 5) oscilloscope, 6) stimulator, 7) function generator and 8) laptop for data acquisition. D Schematic view of the ES setup and wiring. The function generator creates an “on-signal” at 20 Hz frequency. This is used as a trigger for the stimulator to produce the isolated biphasic 6 mA pulses. The resulting applied voltage across the three stimulated wells is measured with an oscilloscope (Ch1 = channel 1, Ch2 = channel 2, TTL trigger = timed transistor-transistor logic trigger). E Diagram of the applied current over time