Electrochemistry of Gala apples: Memristors in vivo

Leon Chua postulated the memristor, a resistor with memory, in 1971 and the first solid-state memristor was built in 2008. Recently, we found memristors in vivo as components of plasma membranes in plants, fruits, roots and seeds. A memristor is a nonlinear element; its current–voltage characteristic is similar to that of a Lissajous pattern. The analysis of presence of memristors in apple fruits is based on cyclic voltammetric characteristics at different frequencies of bipolar voltage waves. The electrostimulation of apple fruits by bipolar periodic triangular or sinusoidal voltage waves induces electrical responses with fingerprints of memristors. Tetraethylammonium chloride, an inhibitor of K⁺ ion channels, transforms memristors to resistors in apple fruits. Memristive properties of apple fruits are linked to the properties of voltage gated K⁺ ion channels. The shape of cyclic voltammograms depends on frequency bipolar triangular or sinusoidal waves. The analytical model of a memristor with a capacitor connected in parallel exhibits different characteristic behavior at low and high frequency of applied voltage, which is the same as experimental data obtained by cyclic voltammetry in vivo. The discovery of memristors in fruits creates a new direction in the modeling and understanding of electrochemical phenomena in fruit ion channels and structures.