Indium selenide-based transistor as an artificial neuronal synapse

– Karthika Kaveri Maiappan

Artificial Neural Networks (ANNs) – a system of interconnected electric circuits or algorithms that communicate with one another just like the neurons in our brain – are gaining popularity for their ability to perform complex tasks, especially in pattern recognition. However, existing devices that mimic neurons and synapses – the junctions between two interacting neurons – operate at high voltages and show variable conductivity, making it difficult to construct efficient ANNs.

To address these concerns, researchers at IISc have developed an Indium selenide-based transistor that was found to mimic several characteristics of a biological synapse. The team, led by Digbijoy Nath at the Centre for Nano Science and Engineering (CeNSE), fabricated a transistor out of multi-layered indium selenide (In₂Se₃), and tested its response to sequential voltage pulses, similar to the electric signals in the neurons.

Communication across biological synapses has certain unique signatures. Prolonged activation of a neuron could make the neuron receiving the signal from it (‘post-synaptic neuron’) either more or less responsive to it, depending on the nature of the signal. The post-synaptic neuron also responds differently to consecutive pulses separated by a very short time interval as compared to a single pulse. The output characteristics of the device captured these essential features.

The researchers used the device’s responses to build a computer model which simulated an ANN. When they trained the ANN with a database of handwritten numbers, it was able to recognise 93% of numbers correctly.

The device, hence, shows promise in constructing more complex neural networks for pattern recognition.

REFERENCE:

Neha Mohta, Ankit Rao, Nayana Remesh, R. Muralidharan and Digbijoy N. Nath, An artificial synaptic transistor using an α-In2Se3 van der Waals ferroelectric channel for pattern recognition, RSC Advances, 2021, 11, 36901-36912

DOI: 10.1039/D1RA07728G

LAB WEBSITE: https://digbijoynath.in/

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