Electrical Circuits That Supply Constant Electric Fields In Vitro

To study the molecular mechanism of galvanotropism in vitro, the strength of an electric field (EF) must be controlled precisely. In this study, I present a culture system that supplies an EF of constant strength by regulating the amount of current supplied to the culture medium. Voltage of the medium was recorded at two fixed points along the current flow throughout the culture period. The voltage drop between the two points was maintained at the desired value by a negative feedback circuit and an operational amplifier. The field strength was defined by the voltage drop and the distance between the two points, and in this system, the EF can range from 0.0005 to 15 mV/mm. This culture system may be a useful tool to determine the nature of galvanotropism.