Memory is a critical component in both computers and human brains, allowing for the storage and accessibility of information. However, the traditional way of computing in computers involves shuttling data back and forth between a memory unit and a central processing unit, leading to inefficiencies known as the von Neumann bottleneck. This separation has contributed to the increasing energy cost of computers, prompting researchers to explore alternatives.
Aleksandra Radenovic from the Laboratory of Nanoscale Biology at EPFL’s School of Engineering is spearheading the research on nanofluidic memristive devices. Unlike traditional electronics that rely on electrons, Radenovic’s device operates using ions, which closely mimics the brain’s energy-efficient method of information processing. This innovative approach aims to develop a nanofluidic neural network that leverages changes in ion concentrations, similar to biological organisms.
The research conducted by Radenovic’s team has been recently published in Nature Electronics, showcasing significant advancements in memristive technology. By utilizing an electrolyte water solution containing potassium ions, the device is capable of switching between on and off states by manipulating the ions present. This flexibility allows for fine-tuning the device’s memory capabilities based on the type of ions used, such as sodium or calcium.
The nanofluidic device was fabricated at EPFL’s Center of MicroNanoTechnology by creating a nanopore in a silicon nitride membrane. The addition of palladium and graphite layers enabled the creation of nano-channels for ions to flow through. As the ions converge at the pore, a blister is formed between the chip surface and graphite, altering the device’s conductivity. This unique mechanism mimics the structural changes that occur in ion channels within biological synapses, providing a more biologically inspired approach to computing.
One of the novel achievements of Radenovic’s team is the observation of the device’s memory action in real-time. Using a specially built microscope, the researchers were able to witness the unique behavior of the highly asymmetric channels (HACs) as they switch between memory states. This real-time visualization offers valuable insights into the functionality of nanofluidic memristive devices, paving the way for further research in the field.
Through collaboration with experts from the Laboratory of Nanoscale Electronics and Structures, the researchers successfully connected two HACs with an electrode to create a logic circuit based on ion flow. This achievement marks the first demonstration of digital logic operations using synapse-like ionic devices, showcasing the potential of nanofluidic technology in expanding the capabilities of computing systems.
Looking ahead, Radenovic’s team aims to connect a network of HACs with water channels to develop fully liquid circuits. The integration of water channels not only provides a built-in cooling mechanism but also opens up opportunities for creating bio-compatible devices. These advancements could have significant applications in fields such as brain-computer interfaces and neuromedicine, revolutionizing the way we approach computing and information processing.
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