SME Actuator for Electrosurgical Instrument Tip Rotation

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Solution Overview

Problem

Existing electrosurgical instruments face challenges in accurately controlling the rotation of their distal tips during minimally invasive procedures, particularly due to friction issues with movable control wires, which can lead to jerky movements and reduced precision, especially in curved instrument channels.

Innovation Solution

The use of a shape memory effect (SME) material actuator, such as nitinol, which undergoes a temperature-induced shape change to rotate the instrument tip, eliminating the need for movable control wires and reducing friction, allowing for precise and smooth control of the tip's orientation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If movable control wires are used to rotate the instrument tip, then the instrument tip can be oriented in different directions, but friction causes jerky movements and reduced precision

Engineering Contradiction:

Improveinstrument tip orientation controlVSAvoidmovement smoothness and precision

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces the mechanical control wire system with a shape memory alloy actuator that uses thermal expansion and phase transformation to rotate the instrument tip. This eliminates the friction inherent in mechanical wire-based systems, providing smooth and precise rotational control without jerky movements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The shape memory alloy actuator changes its physical parameters (shape and length) in response to temperature changes. By heating the alloy, it transforms from a martensitic to an austenitic phase, causing it to expand and rotate the instrument tip to a predetermined angle, thereby achieving precise orientation control.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If a rotatable connection is provided between the instrument tip and coaxial feed cable to maintain electrical connection during rotation, then the instrument tip can be rotated, but the device complexity increases

Engineering Contradiction:

Improveinstrument tip rotation capabilityVSAvoidcontrol mechanism structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts the rotation control function from the electrical connection system. The shape memory alloy actuator independently handles rotation, while the coaxial feed cable maintains a simple fixed connection for electrical power and signal transmission, eliminating the need for complex rotatable electrical connectors.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The shape memory alloy actuator serves multiple functions: it provides rotational movement, maintains electrical connection integrity, and enables precise positioning. This multi-functional approach simplifies the overall device structure by eliminating the need for separate rotation and electrical connection mechanisms.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of operation

If the flexible shaft is rotated to control instrument tip orientation, then the user can control rotation from the proximal end, but the position control accuracy is poor

Engineering Contradiction:

Improveremote rotation controlVSAvoidinstrument tip position accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The shape memory alloy actuator is positioned locally at the distal end of the flexible shaft, close to the instrument tip. This local positioning enables precise control of the tip orientation without the cumulative errors and friction that occur when rotating the entire flexible shaft from the proximal end.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The shape memory alloy actuator is pre-formed with a specific shape that corresponds to the desired instrument tip orientation. When activated by heating, it automatically transforms to this predetermined shape, achieving accurate positioning without requiring complex control mechanisms or feedback systems.

Inventive Principle:

Principle #10Preliminary action

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 solution enhances the reliability and accuracy of electrosurgical instrument tip rotation, reducing the risk of jerky movements and improving control, especially in complex anatomical pathways like the gastrointestinal tract, by utilizing a SME material that changes shape when heated, allowing for precise torque application.

Implementation Method 1

The use of a shape memory effect (SME) material actuator, such as nitinol, which undergoes a temperature-induced shape change to rotate the instrument tip

Methodology Applied

Scientific EffectShape memory effect: Shape Memory Alloy

Implementation Method 2

which undergoes a temperature-induced shape change to rotate the instrument tip

Methodology Applied

Scientific EffectTemperature-induced shape change: Shape Memory Alloy

Data Source

PatentEP3648656B1Control device for an electrosurgical instrument

Publication Date: 2021.12.22 CREO MEDICAL LTD

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AI summary

The invention relates to the use of a shape memory effect (SME) material, such as nitinol, in an actuator for effecting rotation of an electrosurgical instrument. The actuator may be part of a control mechanism for rotating a tip of an electrosurgical instrument relative to a flexible shaft that encases components of the instrument as they are conveyed along an instrument channel of a surgical scoping device, such as an endoscope, bronchoscope, laparoscope, gastroscope, or the like.