Bipolar Electrocautery Articulation With Pulley-Routed Power Cables

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Solution Overview

Problem

Existing mechanisms for powering electrocautery end effectors in robotic surgical instruments with small diameters, such as less than 6 mm, fail to effectively manage power cables without causing strain or interference during articulation, as described in US 2004/0267254, which is designed for larger diameters.

Innovation Solution

A robotic surgical instrument with a pulley arrangement that constrains electrocautery elements and driving elements to symmetrically opposing paths around pulleys, allowing for independent movement and power transmission through the articulation without restriction or slack, using cables that resist compression and tension forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a power cable is fed through the interior of the shaft and articulation to the electrocautery end effector, then power transmission is enabled, but the cable becomes strained or caught during articulation movement

Engineering Contradiction:

Improvepower transmissionVSAvoidcable movement reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The power cable is divided into multiple segments that can move independently through the articulation. Each segment is routed through dedicated channels and pulleys, allowing the cable to flex and move with the articulation without becoming strained or caught, while still transmitting power to the end effector.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Pulleys and channels act as intermediary elements between the power cable and the articulation joints. These intermediaries guide the cable through the moving parts, allowing smooth power transmission while preventing the cable from becoming strained or caught during articulation movement.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the external diameter of the instrument is reduced to less than 6 mm, then tissue damage is minimized and healing is enhanced, but existing power cable management mechanisms become ineffective

Engineering Contradiction:

Improvetissue damageVSAvoidpower cable management adaptability

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The power cable management system is nested within the compact articulation structure. Pulleys and cable routing channels are integrated into the small-diameter articulation mechanism, allowing effective power cable management in instruments with external diameters of less than 6 mm without increasing the overall instrument size.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The power cable is designed with flexible routing through thin-walled channels and pulleys that accommodate the cable's movement within the compact articulation. This flexible design enables effective power transmission in small-diameter instruments while maintaining the instrument's thin profile to minimize tissue damage.

Inventive Principle:

Principle #30Flexible shells and thin films

3Strength

If the power cable is allowed to move freely during articulation, then cable strain is reduced, but the cable becomes slack and catches on internal components

Engineering Contradiction:

Improvecable tensionVSAvoidcable interference

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The power cable routing system is designed to be dynamic, allowing the cable to move and flex with the articulation joints while maintaining appropriate tension. The pulleys and channels guide the cable through its range of motion, preventing both excessive strain and slack that would cause the cable to catch on internal components.

Inventive Principle:

Principle #15Dynamics

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

The solution enables smooth articulation of the electrocautery end effector while maintaining a small diameter, reducing tissue damage and enhancing healing by preventing cable strain or interference, thus improving surgical precision and efficiency.

Implementation Method 1

a pulley arrangement around which the first pair of driving elements and the first and second electrocautery elements are constrained to move

Methodology Applied

Scientific EffectPulley: Pulley

Data Source

PatentUS12471981B2Powering a bipolar electrocautery surgical instrument

Publication Date: 2025.11.18 CMR SURGICAL LTD

AI summary

A robotic surgical instrument comprising a shaft, an electrocautery end effector powered by a first electrocautery element and a second electrocautery element, and an articulation. The articulation connects the electrocautery end effector to the shaft, and comprises a first joint driveable by a first pair of driving elements, the first joint permitting the electrocautery end effector to rotate about a first axis transverse to a longitudinal axis of the shaft. The first joint comprises a pulley arrangement around which the first pair of driving elements and the first and second electrocautery elements are constrained to move, the first and second electrocautery elements having symmetrically opposing paths around the pulley arrangement. The first and second electrocautery elements are distinct from the first pair of driving elements.