Researchers from ETH Zurich, the University of Zurich, and Empa have invented a novel memristor concept that can be utilised in considerably more applications than existing memristors.
The new memristors developed by the researchers may now simply switch between two operation modes while in use: volatile mode, in which the signal weakens over time and dies, and non-volatile mode, in which the signal remains constant. “There are different operation modes for memristors, and it is advantageous to be able to use all these modes depending on an artificial neural network’s architecture. But previous conventional memristors had to be configured for one of these modes in advance,” says ETH postdoc, Rohit John. “These two operation modes are also found in the human brain.”
The researchers created memristors out of halide perovskite nanocrystals, a semiconductor material well known for its usage in solar cells. “The ‘nerve conduction’ in these new memristors is mediated by temporarily or permanently stringing together silver ions from an electrode to form a nanofilament penetrating the perovskite structure through which current can flow,” explains ETH Professor Maksym Kovalenko.
This process can be controlled to make the silver-ion filament thin (volatile mode) or thick (non-volatile mode) such that it gradually breaks down into individual silver ions. The amount of current flowing through the memristor controls this: a weak current activates the volatile mode, whereas a strong current activates the non-volatile mode.
“To our knowledge, this is the first memristor that can be reliably switched between volatile and non-volatile modes on demand,” says Yiğit Demirağ, a doctoral student at the Institute for Neuroinformatics of the University of Zurich and ETH Zurich. This indicates that computer chips with memristors that support both modes will be available in the future. This is a significant advancement because it is typically impossible to mix multiple types of memristors on a single chip.
Read the entire study here.