Memristor Synaptic Weights via Dissolvable Conductive Paths

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Current software-based artificial neural networks lack the efficiency and security of physical hardware implementations, particularly in adjusting synaptic weights for learning and adaptation, which is crucial for applications like cybersecurity and image classification.

Innovation Solution

A physical neural network system utilizing memristors as nonlinear resistors, where synaptic weights are adjusted by controlling the resistance through applied currents, allowing for faster and more secure learning processes, leveraging the temporary dissolvable conductive path method to avoid permanent filament formation and ensure reversible resistance changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If software-based neural networks are used, then flexibility and ease of implementation are improved, but processing speed and security are worsened

Engineering Contradiction:
Improveease of implementationVSAvoidprocessing speed
Core Design Contradiction:
Ease of operationVSSpeed

Solution Approach 1:

The patent replaces software-based neural network operations with physical hardware implementations using memristors. The mechanical/electrical system of memristor resistance changes substitutes the software computation process, achieving faster processing speeds while maintaining the neural network functionality through physical laws rather than software execution.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a physical copy of the neural network structure using memristor arrays that replicate the computational functionality of software-based networks. The memristor network copies the weight adjustment and signal propagation behaviors of software neural networks but executes them through physical electrical processes, improving speed while preserving the original system's operational characteristics.

Inventive Principle:
Principle #26Copying

2Stability of the object's composition

If permanent conductive filaments are formed in memristors, then resistance stability is improved, but adaptability for learning is worsened

Engineering Contradiction:
Improveresistance stabilityVSAvoidadaptability for learning
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic resistance control in memristors where the resistance state can be continuously adjusted during operation. By controlling the formation and dissolution of conductive filaments through applied voltage pulses, the system achieves both stability (when filaments are formed) and adaptability (when filaments are dissolved or partially formed), enabling learning processes while maintaining resistance stability when needed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent employs periodic voltage pulses to control the conductive filament states in memristors. Alternating between formation pulses (creating stable conductive paths) and dissolution pulses (breaking down filaments), the system periodically transitions between stable and adaptable states, enabling both reliable operation and learning-based weight adjustment in a cyclic manner.

Inventive Principle:
Principle #19Periodic action

3Productivity

If high current is applied to adjust memristor resistance, then weight adjustment speed is improved, but harmful effects from filament formation are worsened

Engineering Contradiction:
Improveweight adjustment speedVSAvoidharmful effects from filament formation
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the electrical parameters (current magnitude, pulse width, voltage amplitude) applied to memristors to optimize the trade-off between weight adjustment speed and harmful effects. By using precisely controlled current pulses that are sufficient to adjust resistance quickly but below the threshold for permanent filament formation, the system achieves fast learning while avoiding the harmful side effects of stable conductive path creation.

Inventive Principle:
Principle #35Parameter changes

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 approach enables faster and more secure neural network operations by using memristors to dynamically adjust synaptic weights, enhancing learning efficiency and security, while maintaining low power consumption and minimizing cell-to-cell variations.

Implementation Method 1

at least a first memristor is a substantially nonlinear resistor having a resistance that substantially changes with relation to an electrical current passing through the first memristor

Methodology Applied
Scientific EffectMemristance: Electrical Resistance

Implementation Method 2

the current value is limited to be below a known forming threshold in order to avoid creating a conductive filament within the memristor

Methodology Applied
Scientific EffectConductive path formation: Conduction (electrical)

Data Source

PatentUS11568221B2Artificial neuron synaptic weights implemented with variable dissolvable conductive paths
Publication Date: 2023.01.31 ARIZONA BOARD OF REGENTS ACTING FOR & ON BEHALF OF NORTHERN ARIZONA UNIV
  • US11568221B2 patent drawing
  • US11568221B2 patent drawing
  • US11568221B2 patent drawing

AI summary

A low-power, controllable, and reconfigurable method to control weights in model neurons in an Artificial Neural Network is disclosed. Memristors are utilized as adjustable synapses, where the memristor resistance reflects the synapse weight. The injection of extremely small electric currents (a few nanoamperes) in each cell forces the resistance to drop abruptly by several orders of magnitudes due to the formation of a conductive path between the two electrodes. These conductive paths dissolve as soon as the current injection stops, and the cells return to their initial state. A repeated injection of currents into the same cell results in an almost identical effect in resistance drop. Different, stable resistance values in each cell can be controllably achieved by injecting different current values.