Adjustable-Bending Stiffness Steerable Needle
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Solution Overview
Problem
Conventional steerable needles face challenges in accurately controlling bending stiffness and preventing buckling phenomena during intervention treatments in soft tissues, limiting their ability to navigate complex paths and causing damage to tissues.
Innovation Solution
An adjustable-bending stiffness steerable needle system featuring a cylindrical core wire, a bevel-shaped or cone-shaped tip, a compression spring, and a rigid shaft, with a mechanism to control bending stiffness through passive or active compression of the spring, allowing for precise steering and buckling prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible needle with low bending stiffness is used to enable steering through bending, then the needle can be steered by interactive force with the tissue, but the curvature of the path is small and accurate steering control is difficult
Solution Approach 1:
The needle shaft transitions from a static rigid structure to a dynamic segmented structure with adjustable stiffness. The tube elements can be selectively engaged or disengaged from the core wire, allowing the needle to switch between flexible (steerable) and rigid (stable) states during insertion, thus resolving the contradiction between steering capability and steering accuracy.
Solution Approach 2:
The bending stiffness of the needle is changed by modifying the structural configuration - specifically by controlling the engagement state of the tube elements with the core wire. When disengaged, the needle is flexible for steering; when engaged, the needle becomes rigid for precise positioning, thereby achieving both steering accuracy and positioning precision.
2Adaptability or versatility
If a flexible needle is used to insert through soft tissue, then the needle can navigate curved paths, but buckling phenomenon occurs when insertion distance is long or hard regions are encountered
Solution Approach 1:
The needle shaft is designed as a dynamic structure where tube elements can be selectively engaged with the core wire. During curved path navigation, the tube elements are disengaged to allow flexibility; when approaching hard regions or long insertion distances, the tube elements are engaged to increase stiffness and prevent buckling, thus resolving the contradiction between path navigation capability and buckling resistance.
Solution Approach 2:
The needle shaft is divided into multiple segmented tube elements that can independently engage or disengage from the core wire. This segmentation allows different portions of the needle to have different stiffness characteristics - flexible sections for navigation and rigid sections for buckling prevention - simultaneously satisfying both requirements.
3Reliability
If the bending stiffness of the needle is increased to prevent buckling, then buckling phenomenon is reduced, but the curvature of the steerable path becomes low and applicable treatment procedures are limited
Solution Approach 1:
The needle's bending stiffness is made dynamically adjustable through the engagement mechanism between tube elements and core wire. For procedures requiring high curvature paths, the tube elements are disengaged to provide flexibility; for procedures requiring deep insertion or hard tissue penetration, the tube elements are engaged to provide rigidity and prevent buckling, thus resolving the contradiction between buckling prevention and treatment procedure applicability.
4Device complexity
If conventional steerable needles with fixed bending stiffness are used, then the structure is simple, but it is impossible to control the intrinsic bending stiffness and accurate steering control is difficult
Solution Approach 1:
The needle shaft is segmented into multiple tube elements that can be selectively engaged with the core wire. This segmentation provides a mechanically simple yet effective means to control bending stiffness - by controlling which segments are engaged, the overall stiffness is adjusted without complex mechanisms, thus resolving the contradiction between structural simplicity and steering control accuracy.
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
Enables more accurate and safe navigation of complex paths within soft tissues, minimizing tissue damage and improving treatment efficacy by actively or passively controlling bending stiffness and preventing buckling.
Implementation Method 1
a compression spring fastened to the other end of the needle shaft, and configured such that the core wire passes therethrough
Data Source
AI summary
Disclosed herein are an adjustable-bending stiffness steerable needle, a buckling-preventing steerable needle, and a steerable needle system including the same. The adjustable-bending stiffness steerable needle includes a cylindrical core wire, a tip portion, a needle shaft, a compression spring, and a rigid shaft. The tip portion has a bevel shape, and is connected to the front end of the core wire. The needle shaft is disposed such that one end thereof is separable from the tip portion and the needle shaft surrounds the core wire. The compression spring is fastened to the other end of the needle shaft, and is configured such that the core wire passes therethrough. The rigid shaft is connected to the core wire having passed through the compression spring, and is also connected to the compression spring. The needle shaft includes a plurality of hollow tube elements that is separable from each other.