Professor Leon Chua, the originator of the term memristor for a variable resistance device with pinched hysteresis behavior, has joined forces with Professor Christofer Toumazou and Themistoklis Prodromakis, both of Imperial College London, to demonstrate that the behavior has been observed for more than 200 years.
The three academics have authored a commentary in the latest edition of Nature Materials
under the title Two centuries of memristors
Chua originally postulated the existence of a fourth fundamental passive electronic circuit element as a consequence of electrical theory and coined the term memristor in 1971. Hewlett Packard Co. picked up use of the terminology and produced an electronic circuit element based on titanium oxide in 2008.
In fact such variable resistance systems can be based on a wide variety of physical systems including movement of mobile ions or oxygen vacancies, the formation and rupture of conductive filaments and phase changes in materials.
In their paper Prodromakis, Toumazou and Chua examine some of the earliest and most fundamental experiments in electricity and find evidence of memristor behavior in a variety of studies, including those of the electric arc by Hertha Ayrton and of thermistors by Michael Faraday. The oldest they touch on are those of Sir Humphry Davy, inventor of the electric arc and Faraday's mentor, who performed experiments using voltaic piles in 1808 and subsequent years.
The conclusion is that the memristor is not an invention but a description of a natural phenomenon that can be found in many dissipative devices made from many materials, internal structures and architectures. It adds that observation of memristor behavior just happens to be older than the first formal discussions of the resistor (Ohm in 1827) and the inductor (Faraday in 1831).Related links and articles:
Nature Materials commentary
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