The Fourth Basic Circuit Element

The "memristor", or memory resistor, previously resided as a theoretical fourth basic electric circuit element next to the resistor, capacitor and inductor. Its function is to "remember" the amount of current that passed through it by varying its resistance accordingly and keeping that information even after all power has been removed from the circuit. In 1971 Professor Leon Chua theorized the necessary existence of this circuit element in his publication titled "Memristor-The missing circuit element" (abstract).

Scientists at the Information and Quantum Systems lab at HP Labs are beginning to demonstrate that this circuit element exists by combining 2 layers of titanium oxide sandwiched between two wires. One layer is made of standard TiO2, the other is made of a layer where 1 percent is missing some oxygen. When current is applied, the oxygen vacancies move from one side to the other changing each layer's resistance. The scientists claim the switching action happens faster than they can even measure. Because this material can be arranged into much denser arrays than transistors, the potential for large zero-power memory storage and computers that boot instantly while retaining their last powered state may be in our near future. Some are even predicting the eventual phasing out of transistors as the new technology develops.