The “Edge of Chaos” Amplifies Signals Without Transistors
Emulating the edge of chaos of axons enables a metal wire to overcome its resistance without cooling, thereby amplifying signals flowing inside of it.
The Science
A stubbed toe sends pain signals immediately to the brain through many meters of axons, a part of the nerve made of very resistive fleshy material. These axons use a concept called the “edge of chaos” or semi-stability, which allows the quick and accurate movement of information. This work showed the edge of chaos working in a real artificial system by running electricity through an inorganic material. The edge of chaos normally amplifies noise. But surprisingly, a metallic wire on top of a material at the edge of chaos moved and amplified useful signals. This overcomes the resistive loss of a metal that makes signals lose information.
The Impact
Today’s electronic chips have many components and miles of metal wires, or interconnects. This causes resistive signal losses to dominate power use in chips. The current fix for this problem is to cut the wires in chips into much shorter segments and add transistors to amplify and pass on the weakened signals. This new work overcomes the need for transistor amplifiers. It also allows a long metal line to embody not only superconductor-like zero electrical resistance, but also to amplify small signals. This result could revolutionize chip design by making chips dramatically simpler and more efficient.
Summary
Electrical signals traveling through metallic conductors lose strength due to the inherent resistance of the metal. To compensate, traditional methods require repeatedly disrupting the conductor to insert amplifiers that regenerate the signal. This technique, which has been used for more than a century, limits the design and performance of modern, densely interconnected chips. In contrast, this work introduces a new approach based on harnessing the semi-stable edge of chaos (EOC), a regime that scientists theorized but have not previously demonstrated. This regime supports active signal transmission similar to the self-amplification seen in biological axons.
By electrically accessing the spin crossover in lanthanum cobaltite (LaCoO3), the researchers isolated the semi-stable EOC and invoked negative resistance and signal amplification in a metallic transmission line without the need for separate amplifiers, and at normal temperatures and pressures. Operando thermal mapping revealed that the energy used to maintain the EOC is not fully lost as heat, but is partly redirected to amplify the signal, thereby enabling continuous active transmission and potentially revolutionizing chip design and performance.
Contact
R. Stanley WilliamsTexas A&M University
[email protected]
Funding
This work was primarily supported as part of the Center for Reconfigurable Electronic Materials Inspired by Nonlinear Neuron Dynamics (reMIND), an Energy Frontier Research Center (EFRC) funded by the Department of Energy Office of Science, Basic Energy Sciences. The Laboratory Directed Research and Development (LDRD) program at Sandia National Laboratories provided internal support to the reMIND EFRC. All authors of this work were supported directly by reMIND or by the LDRD program.
Publications
Brown, T.D., et al. (reMIND), Axon-like active signal transmission. Nature (2024). [DOI: 10.1038/s41586-024-07921-z]
Related Links
Axon-mimicking materials for computing, TAMU Engineering News
Neuromorphic Wires Amplify Their Own Signals, IEEE Spectrum
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