A groundbreaking discovery at the University of Limerick in Ireland has shown for the first time that unconventional, brain-like computing is possible at the smallest scale of atoms and molecules.
Researchers at the University of Limerick’s Bernal Institute worked with an international team of scientists to create a new type of organic material that learns from its past behavior.
The discovery of the ‘dynamic molecular switch’ that mimics synaptic behavior is revealed in a new study in the international journal natural materials.
The study was led by Damien Thompson, Professor of Molecular Modeling in UL’s Department of Physics and Director of SSPC, UL-hosted Science Foundation Ireland Research Center for Pharmaceuticals, together with Christian Nijhuis of the Center for Molecules and Brain-Inspired Nano Systems University of Twente and Enrique del Barco from the University of Central Florida.
Working during lockdown, the team developed a two-nanometer thick layer of molecules, 50,000 times thinner than a strand of hair, that remembers its history when electrons pass through it.
Professor Thompson explained that “the switching probability and the values of the on/off states in the molecular material are constantly changing, presenting a disruptive new alternative to traditional silicon-based digital switches, which can only be either on or off at any one time”.
The newly discovered dynamic organic switch demonstrates all the mathematical logic functions required for deep learning and successfully emulates Pavlovian “call and response” synaptic brain-like behavior.
Researchers demonstrated the new material properties using extensive experimental characterization and electrical measurements, supported by multiscale modeling ranging from predictive modeling of the molecular structures at the quantum level to analytical mathematical modeling of the electrical data.
To mimic the dynamic behavior of synapses at the molecular level, the researchers combined rapid electron transfer (similar to action potentials and rapid depolarization processes in biology) with slow, diffusion-limited proton coupling (similar to the role of biological calcium ions or neurotransmitters).
Because the electron transfer and proton coupling steps take place at vastly different time scales within the material, the transformation can emulate the plastic behavior of synapse-neuron connections, Pavlovian learning, and all logic gates for digital circuits simply by changing the applied voltage and the duration of voltage pulses during the Synthesis, they explained.
“This has been a great lockdown project, with Chris, Enrique and I pushing each other through Zoom meetings and gargantuan email threads to get our teams to the point with combined skills in materials modeling, synthesis and characterization that we could use to demonstrate the properties of these new brain-like computers,” explained Professor Thompson.
“The community has long known that silicon technology works very differently from our brains, so we used novel electronic materials based on soft molecules to emulate brain-like computing networks.”
The researchers explained that in the future the method can be applied to dynamic molecular systems driven by other stimuli such as light and coupled to different modes of dynamic covalent bond formation.
This breakthrough opens up a whole range of adaptive and reconfigurable systems and creates new possibilities in sustainable and green chemistry, from more efficient production of drugs and other value-added chemicals through flow chemistry to the development of new organic materials for high-density computing and storage in memory large data centers.
“That’s just the beginning. We are already expanding this next generation of smart molecular materials that will enable the development of sustainable alternative technologies to address major energy, environmental and health challenges,” said Professor Thompson.
Professor Norelee Kennedy, UL’s Vice President of Research, said, “Our researchers are constantly finding new ways to create more effective and sustainable materials. This latest finding is very exciting, demonstrates the scope and ambition of our international collaboration, and demonstrates our world-leading ability at UL to encode useful properties into organic materials.”