Neuromorphic Synapse Using Multi-Layer Carbon Nanotubes

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Solution Overview

Problem

Current neuromorphic devices face challenges in achieving linear resistance changes in synapses, which are crucial for mimicking brain-like learning and memory functions, due to limitations in the structural and electrical properties of existing synapse materials.

Innovation Solution

The use of carbon nano-tubes with varying lengths, diameters, and structures in multiple layers within the synapse, along with a capping layer of densely arranged horizontal carbon nano-tubes, allows for controlled resistance changes in response to electrical pulses, enabling efficient learning and memory operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing synapse materials are used in neuromorphic devices, then device structure can be maintained, but linear resistance changes required for brain-like learning functions cannot be achieved

Engineering Contradiction:
Improvelinear resistance change capabilityVSAvoidbrain-like learning function
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by systematically varying multiple characteristics of carbon nanotubes including length, diameter, wall structure (single-wall, double-wall, multi-wall), and arrangement density across different synapse layers. These parameter variations enable precise control over resistance states and conductance changes, achieving the linear resistance changes necessary for mimicking biological synapse behavior and enabling brain-like learning functions.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials by creating a multi-layered synapse structure where each layer contains carbon nanotubes with specific structural parameters. The combination of different carbon nanotube types (single-wall, double-wall, multi-wall) with varying dimensions and densities forms a composite material system that achieves superior electrical properties and linear resistance modulation compared to single-material synapses.

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If multiple layers of carbon nano-tubes with different structures are used in the synapse, then resistance control precision is improved, but device complexity increases

Engineering Contradiction:
Improveresistance control precisionVSAvoidsynapse layer structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the synapse into multiple distinct layers, where each layer contains carbon nanotubes with specific structural parameters (length, diameter, wall structure). This segmentation allows independent optimization and control of resistance characteristics for each layer, enabling precise overall resistance control while maintaining a systematic and manufacturable multi-layer architecture.

Inventive Principle:
Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration enables stable and gradual changes in resistance and conductance, facilitating effective learning and memory functions by allowing synapses to transition between low and high resistance states, thereby enhancing the neuromorphic device's ability to process and retain data.

Implementation Method 1

The synapses of the neuromorphic device have multiple resistance levels. The resistance of the synapses should be linearly changed.

Methodology Applied
Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

This configuration enables stable and gradual changes in resistance and conductance, facilitating effective learning and memory functions by allowing synapses to transition between low and high resistance states

Methodology Applied
Scientific EffectConduction (electrical): Conduction (electrical)

Data Source

PatentUS10559626B2Neuromorphic device including a synapse having carbon nano-tubes
Publication Date: 2020.02.11 SK HYNIX INC
  • US10559626B2 patent drawing
  • US10559626B2 patent drawing
  • US10559626B2 patent drawing

AI summary

A neuromorphic device is provided. The neuromorphic device may include a pre-synaptic neuron; a row line extending in a row direction from the pre-synaptic neuron; a post-synaptic neuron; a column line extending in a column direction from the post-synaptic neuron; and a synapse disposed at an intersection between the row line and the column line. The synapse may include a first synapse layer including a plurality of first carbon nano-tubes; a second synapse layer including a plurality of second carbon nano-tubes having different structures from the plurality of first carbon nano-tubes; and a third synapse layer including a plurality of third carbon nano-tubes having different structures from the plurality of first carbon nano-tubes and the plurality of second carbon nano-tubes.