Researchers from HP Labs have proven the existence of what had previously been only theorized as the fourth fundamental circuit element in electrical engineering.
This scientific advancement could make it possible to develop computer systems that have memories that do not forget, do not need to be booted up, consume far less power and associate information in a manner similar to that of the human brain.
According to one of the researchers a common analogy for a resistor is a pipe that carries water. The water itself is analogous to electrical charge, the pressure at the input of the pipe is similar to voltage, and the rate of flow of the water through the pipe is like electrical current. Just as with an electrical resistor, the flow of water through the pipe is faster if the pipe is shorter and/or it has a larger diameter. An analogy for a memristor is an interesting kind of pipe that expands or shrinks when water flows through it. If water flows through the pipe in one direction, the diameter of the pipe increases, thus enabling the water to flow faster. If water flows through the pipe in the opposite direction, the diameter of the pipe decreases, thus slowing down the flow of water. If the water pressure is turned off, the pipe will retain it most recent diameter until the water is turned back on. Thus, the pipe does not store water like a bucket (or a capacitor) - it remembers how much water flowed through it.
Memristors have previously been seen by researchers before but they were apparently not aware of it. Leon Chua, a distinguished faculty member in the Electrical Engineering and Computer Sciences Department of the University of California at Berkeley, initially theorized about and named the element in an academic paper published 37 years ago. Chua argued that the memristor was the fourth fundamental circuit element, along with the resistor, capacitor and inductor, and that it had properties that could not be duplicated by any combination of the other three elements.
Building on their groundbreaking research in nanoelectronics, the HP Labs researchers are the first to prove the existence of the memristor.
By providing a mathematical model for the physics of a memristor, Hewlett Packard's research facility HP Labs has made it possible for engineers to develop integrated circuit designs that could improve the performance and energy efficiency of PCs.
One application for this research could be the development of a new kind of computer memory that would supplement and eventually replace today's commonly used dynamic random access memory (DRAM).
Computers using conventional DRAM lack the ability to retain information once they lose power. When power is restored to a DRAM-based computer, a slow, energy-consuming "boot-up" process is necessary to retrieve data from a magnetic disk required to run the system.
In contrast, a memristor-based computer would retain its information after losing power and would not require the boot-up process, resulting in the consumption of less power and wasted time.
Harper's magazine earlier this year suggested that Google's new data centre at the Dalles in Oregon USA, is projected to use enough electricity by 2011 to power a staggering 82,000 homes - Memristor-based memory and storage could play a significant role to reduce much of the energy required and in the face of power interruptions provide a more reliable service.
Another potential application of memristor technology could be the development of computer systems that remember and associate series of events in a manner similar to the way a human brain recognizes patterns. This could substantially improve today's facial recognition technology, enable security and privacy features that recognize a complex set of biometric features of an authorized person to access personal information, or enable an appliance to learn from experience.
In April this year a paper was published in Nature - four researchers at HP Labs' Information and Quantum Systems Lab, led by R. Stanley Williams, presented the mathematical model and a physical example of a "memristor" - a blend of "memory resistor" - which has the unique property of retaining a history of the information it has acquired.
For more attend Printed Electronics USA 2008.
References: HP Labs, Harper's Magazine
