Cannula Overtube Sensors for Bodywall Force Feedback

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Solution Overview

Problem

During minimally invasive surgeries, surgeons lose the ability to sense the force exerted on internal body tissues due to the distance from the surgical site, leading to potential tissue trauma from lever actions and instrument collisions within the cannula.

Innovation Solution

A cannula design featuring an elongated inner tube and an overtube with sensors on the overtube to isolate forces from instrument collisions and measure bodywall loads, allowing for accurate force feedback without direct contact between the instrument and overtube.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If surgeons perform minimally invasive surgery through cannula, then surgical access to internal body cavity is achieved, but ability to sense force on internal tissues is lost

Engineering Contradiction:

Improvesurgical accessVSAvoidforce feedback

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

A force sensing device is introduced as an intermediary component within the cannula system. The device includes a first portion that contacts the body wall and a second portion that contacts the instrument, with a sensing mechanism between them that measures force without requiring direct contact between the surgeon and the internal tissue

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct mechanical force sensing by the surgeon with an electronic sensing system. Force sensors (such as strain gauges or load cells) are integrated into the cannula to convert mechanical force into electrical signals that can be transmitted to the surgeon through tactile feedback or visual display

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If instruments are manipulated within the cannula, then surgical procedures can be performed, but tissue trauma occurs due to lever actions and instrument collisions

Engineering Contradiction:

Improvesurgical procedure capabilityVSAvoidtissue trauma

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The force sensing device provides real-time feedback to the surgeon about forces being applied to internal tissues. This feedback loop allows the surgeon to adjust their manipulation techniques to avoid excessive forces that could cause tissue trauma, while still maintaining the ability to perform surgical procedures

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The cannula design includes features such as rounded instrument tips and controlled flexibility in the instrument shaft that cushion the impact of potential collisions with tissues before significant damage can occur

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Measurement precision

If sensors are placed on the inner tube to measure force, then force measurement is achieved, but instrument collision forces interfere with bodywall load measurement

Engineering Contradiction:

Improveforce measurementVSAvoidmeasurement interference

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The sensing device is divided into separate functional portions: a first portion that interfaces with the body wall and a second portion that interfaces with the instrument. This segmentation allows the sensing mechanism to measure bodywall forces independently from instrument collision forces, as each portion is responsible for detecting specific force components

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sensing mechanism acts as an intermediary between the inner tube and the outer tube, measuring forces transmitted through the inner tube while being protected from direct impact by the outer tube. This intermediary positioning allows accurate measurement of bodywall loads without interference from instrument collisions

Inventive Principle:

Principle #24Intermediary (Mediator)

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 cannula provides precise force feedback to the surgeon, reducing tissue trauma by isolating instrument collision forces and accurately measuring bodywall loads, enhancing surgical precision and safety.

Implementation Method 1

Strain gauges or other sensors 614 are disposed on the overtube 606 to provide an indication of forces applied to an outer wall 618 of the overtube

Methodology Applied

Scientific EffectStrain measurement: Piezoresistive Effect

Data Source

PatentUS20220378474A1Cannula with sensors to measure patient bodywall forces

Publication Date: 2022.12.01 INTUITIVE SURGICAL OPERATIONS INC

AI summary

A cannula is provided that includes a head portion that defines a proximal opening sized to receive one or more surgical instruments; an elongated inner tube rigidly fastened to the head portion defines an elongated conduit; a surgical instrument can be inserted within the conduit; an elongated overtube rigidly fastened to the head portion is coaxially aligned with the inner tube and extends about a portion of the inner tube; an inner wall of the overtube is spaced apart from an outer wall of the inner tube; sensors are disposed on the overtube to provide an indication of forces applied to the outer wall of the overtube in a direction generally transverse to the longitudinal dimension of the overtube.