Multi-force sensing instrument for retinal microsurgery

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Solution Overview

Problem

Current robotic systems for retinal microsurgery lack effective multi-force sensing capabilities, particularly in measuring forces applied at the sclera entry point and their location on the tool shaft, which can lead to excessive force on the retina, potentially causing hemorrhage or tearing, and hinder precise instrument motion due to inadequate feedback on tool-to-tissue interaction.

Innovation Solution

A multi-force sensing instrument with a tool shaft equipped with strain sensors and torque-force sensors, along with a signal processor to determine the magnitude and position of lateral forces applied between these sensors, providing feedback for robotic systems to ensure precise control and minimize eye motion during retinal microsurgery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If force sensing is added to robotic surgical instruments, then safety and precision are improved, but device complexity increases

Engineering Contradiction:
ImprovesafetyVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent embeds multiple strain sensors within the hollow structure of the instrument shaft, nesting sensing elements inside the existing mechanical framework. This allows force sensing capability to be integrated without adding external components, thereby improving safety while minimizing increases in device complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The strain sensors serve multiple functions: they detect lateral forces, determine force application positions, and provide feedback for robotic control. This multi-functionality allows a single sensing system to address multiple safety and precision requirements simultaneously, improving reliability without proportionally increasing complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If multiple strain sensors are placed along the tool shaft to detect force position, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improveforce position detectionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The tool shaft is divided into multiple sensing zones by placing strain sensors at different positions along its length. Each sensor segment detects forces in its specific region, enabling precise localization of force application. This segmentation approach improves measurement precision while keeping each individual sensor simple.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from single-point force detection to distributed multi-point detection along the length of the shaft. By adding the spatial dimension of sensor distribution, the system can determine both magnitude and position of forces, significantly improving measurement precision without requiring complex single-point sensors.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If force feedback control is implemented, then surgical precision is improved, but system complexity increases

Engineering Contradiction:
Improvesurgical precisionVSAvoidsystem complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements a feedback loop where strain sensors detect forces applied during surgery, the control system processes this information, and the robot adjusts its motion accordingly. This feedback mechanism enables real-time force control, improving surgical precision by preventing excessive forces while maintaining intuitive robot behavior.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces complex mechanical force feedback mechanisms with electronic sensing and software-based control. Instead of using mechanical springs or levers to provide force feedback, the system uses strain sensors and computational algorithms to achieve force control, reducing mechanical complexity while maintaining or improving precision.

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

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 system enhances safety and usability by accurately measuring and controlling forces applied during retinal microsurgery, reducing the risk of retina damage and improving surgical precision by providing intuitive robot behavior and scaled feedback, enabling precise manipulation within the eye.

Implementation Method 1

a strain sensor arranged at a first position along the tool shaft, at least one of a second strain sensor or a torque-force sensor arranged at a second position along the tool shaft

Methodology Applied
Scientific EffectStrain: Deformation

Data Source

PatentEP3148472B1Multi-force sensing instrument for robotic surgical systems
Publication Date: 2022.10.05 JOHNS HOPKINS UNIVERSITY
  • EP3148472B1 patent drawingFigure 1A~1B
  • EP3148472B1 patent drawingFigure 2A~2D
  • EP3148472B1 patent drawingFigure 2E

AI summary

A multi-force sensing instrument includes a tool that has a tool shaft having a distal end and a proximal end, a strain sensor arranged at a first position along the tool shaft, at least one of a second strain sensor or a torque-force sensor arranged at a second position along the tool shaft, the second position being more towards the proximal end of the tool shaft than the first position, and a signal processor configured to communicate with the strain sensor and the at least one of the second strain sensor or the torque-force sensor to receive detection signals therefrom. The signal processor is configured to process the signals to determine a magnitude and position of a lateral component of a force applied to the tool shaft when the position of the applied force is between the first and second positions.