Modern electronic devices are based on circuit elements like resistors, capacitors, and inductors. However, there’s a fourth still-experimental type of component called a memristor. Engineers have been trying to perfect the memristor for years, but so far attempts to make these components a reality have failed on one or more fronts. However, a new organic memristor design from an international team of scientists could solve most of the outstanding problems and finally make these components commercially viable.
The memristor was first theorized in the early 1970s, but the technology of the day was not sophisticated enough to build one. A memristor is a two-terminal electrical component that has properties of both resistors and non-volatile memory. The electrical resistance isn’t constant, but changes based on the charge that has passed through the memristor in the past. That is, it remembers its history even if the power is shut off.
Past memristor designs in laboratories have failed in at least one of several ways. They were often too slow to switch states, or they just didn’t retain their memory for very long after the power was cut. The new organic memristor designed by a team of researchers led by Thirumalai Venky Venkatesan at the National University of Singapore is able to switch states in just 50 nanoseconds, similar to traditional resistors. It can also hold that state for more than 11 days without power.
HP memristor die/wafer shot.
The memristor is composed of the transition metal ruthenium complexed with “azo-aromatic ligands.” The theoretical work enabling this material was performed at Yale, and the organic molecules were synthesized at the Indian Association for the Cultivation of Sciences. Despite containing organic molecules, the memristors are very stable. No degradation of the on/off ratio after more than 10^12 read cycles. Venkatesan says this material is easy and cheap to make. None of the materials needed are particularly rare or dangerous, and fabrication techniques are based on existing technology.
There’s still a lot of work to be done before memristors will be ready for consumer devices, but the effects on daily life could be huge when that day arrives. Memristors could replace both storage and RAM with a single chip, and the capacity of memristor-based devices could be almost unfathomably huge. Some theoretical designs for multi-layer memristors have a storage capacity of 1 petabyte per cubic centimeter. Maybe spinning hard drives won’t be the capacity kings for as long as we thought.