Development of a portable impedance detection system for monitoring the growth of mouse L929 cells

A portable impedance measurement system was used to monitor the growth of L929 cells. The interdigitating microelectrodes of our portable system were produced by microfabrication technology with a width of 8. μm, a gap of 8. μm, and a length of 500. μm. These microelectrodes provided a high electric field for AC impedance measurements. When mouse L929 cells were cultured on the electrode surface and pre-coated with poly-l-lysine, the changes in the impedance on the interdigitating electrodes represented the lag, log, and stationary phases of a typical cell growth curve. The impedance measurement result was fitted to an equivalent circuit, which showed that the capacitance signal was the major contributor to the total impedance of the cell culture. The capacitance arises from the cell capacitance, the double-layer capacitance and the capacitance of the poly-l-lysine-coated surface, and the changes in capacitance were probably due to cell proliferation and the resulting changes in cell metabolites. To make the device portable and provide rapid results, we designed a novel impedance detection system comprised of a microprocessor, an AD5933 impedance converter (IC), and the interdigitating microelectrodes. This device was successfully used to observe the changes in the metabolism and proliferation of L929 cells at different stages of cell growth with low cell concentrations. Further, the portable impedance measurement device is a useful analytical tool for monitoring cell growth. It will integrate easily with wireless circuits for applications in aseptic cell biology.