Nonlinear properties of biological suspensions have been previously presented as a bulk phenomenon, however, some authors consider that they are generated at the electrode-electrolyte interface and are reflected as a bulk property phenomenon. They were mainly ascribed to the H⁺-ATPase present in the plasma membrane of these cells. In this paper, we describe the construction of a dual-cell nonlinear dielectric spectrometer. The system is applied to the study of interfaces with resting cell suspensions of Saccharomyces cerevisiae. Substantial harmonics are generated at the interface when a sinusoidal current is applied and altered by the presence of yeast. When a second interface with yeast and enzyme inhibitor is used as reference, a decrease in the magnitude response of the third harmonic can be observed. As it was already described for the solution bulk, we obtained a similar behavior at the interface. Besides, we also found optimal intervals, respectively, for frequency and voltage to reach maximal response. This result would support the contention that biological nonlinearity is an interface-based phenomenon.