New molecular computing device that recalls brain plasticity has been developed
Remembering the plasticity of connections in the human brain, a new molecular device can be reconfigured for different computational tasks simply by changing the applied voltages. It is the result of a discovery published in the journal Nature, on which an international team of researchers worked.
The nerve cells can store memories, and the same device may also retain information for future retrieval and processing. “The brain has the amazing ability to change its wiring by making and breaking the connections between nerve cells. Achieving something comparable in a physical system has been extremely challenging, ”said Dr. R. Stanley Williams, professor in the Department of Electrical and Computer Engineering at Texas A&M University. “Now we have created a molecular device with extraordinary reconfigurability, which is achieved by not modifying the physical connections as in the brain, but reprogramming its logic “.
Von Neumann’s bottleneck
Whether it’s the familiar laptop or a sophisticated supercomputer, digital technologies face a common nemesis, the von Neumann’s bottleneck. This delay in computational processing is a consequence of current computer architectures, in which the memory, containing data and programs, it is physically separate from the processor. Consequently, computers employ a significant amount of time to transfer information between the two systems, causing the bottleneck. Also, despite extremely high processor speeds, these drives can remain idle for extended periods of time during periods of information exchange.
As an alternative to the conventional electronic parts used for the design of memory units and processors, the devices called memristors offer a way around von Neumann’s bottleneck. Memristors, such as those made of niobium dioxide and vanadium dioxide, go from being an insulator to a conductor at a set temperature. This property gives these types of memristors the ability to perform calculations and store data.
However, despite their many advantages, these metal oxide memristors are made from rare earth elements and can only function at restrictive temperature regimes. Hence, there has been an ongoing search for promising organic molecules that can perform a comparable memristive function.
The compound has a central metal atom (iron) bonded to three organic phenylazo pyridine molecules called ligands. “This behaves like an electronic sponge that can absorb up to six electrons reversibly, resulting in seven different redox states,” Sreebrata said. “The interconnection between these states is the key behind the reconfigurability shown in this work.”
Scientists studied the molecular mechanisms underlying the curious switching behavior using an imaging technique called Raman spectroscopy. In particular, they tried spectral signatures in the vibrational motion of the organic molecule that could explain the multiple transitions. Their investigation revealed that sweeping the negative voltage triggered the ligands on the molecule to undergo a series of electron reduction, or acquisition, events that caused the molecule to transition between the off and on states.