Dielectrophoresis (DEP) is a physical effect that generates a force on a polarisable particles experiencing a non-homogeneous electric field. It has been shown that this effect depends on the electrical properties of that particle, i.e. the electrical permittivity and conductivity. In the past, DEP-based techniques were applied to measure the electric properties of one or several cells at a time. The results showed that the measure of electrical properties by DEP is very sensitive to noise. However, further improvements are possible by generating more information from the experiments: this paper presents a rapid automated system that measures the DEP spectrum from a large population of cells with a low level of noise using the microwell electrodes, and a method of analysis that provides additional information about the electrical properties of the cells and a new theoretical approach was developed to obtain accurate, bias-free results in under five minutes.