Self-straightening needle assembly for neurosurgery
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Solution Overview
Problem
Current neurosurgical devices face challenges in accurately targeting intracranial regions due to inaccuracy in curved needle trajectories and susceptibility to deflection from tissue forces, which can result in damage to healthy brain tissue and miss the intended target during minimally invasive procedures.
Innovation Solution
A robotic needle assembly with a stiff, straight outer cannula and a self-straightening inner element, where the middle cannula has a naturally curved shape and is robotically controlled to minimize tissue damage by tracing a pre-defined path, ensuring the tip's precise positioning and resistance to lateral forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible needle is used to reach off-axis targets, then accessibility to target regions is improved, but trajectory accuracy deteriorates due to needle deflection from tissue forces
Solution Approach 1:
The needle assembly is divided into multiple concentric segments (outer cannula, middle cannula, inner element) that can move independently. The middle cannula with lateral slots allows selective bending while the inner element maintains straightness, enabling the system to achieve both flexibility for off-axis access and precision for accurate targeting.
Solution Approach 2:
Different segments of the needle assembly have different mechanical properties. The middle cannula is designed with lateral slots to be flexible in specific directions for navigation, while the inner element remains stiff and straight for precise tip positioning. This local differentiation of mechanical properties resolves the contradiction between flexibility and accuracy.
2Measurement precision
If a straight needle is used to maintain trajectory accuracy, then measurement precision is improved, but adaptability to reach off-axis targets deteriorates
Solution Approach 1:
The needle assembly transitions from a static straight configuration to a dynamic system where the middle cannula can bend at lateral slots while the inner element remains straight. This dynamic capability allows the needle to adapt its shape for off-axis access while maintaining trajectory accuracy through robotic control of the bending segments.
Solution Approach 2:
The middle cannula acts as an intermediary between the outer cannula and inner element. It provides the flexibility needed for off-axis navigation while the inner element maintains straightness for accurate targeting. The middle cannula's selective bending capability mediates between the conflicting requirements of flexibility and precision.
3Ease of operation
If the needle is made more flexible to navigate tissue, then ease of operation is improved, but reliability deteriorates due to susceptibility to deflection from tissue forces
Solution Approach 1:
The needle is segmented into flexible and rigid portions. The middle cannula with lateral slots provides flexibility for navigation while the inner element maintains rigidity for reliable tip positioning. This segmentation allows the system to navigate tissue easily while resisting deflection forces that would compromise reliability.
Solution Approach 2:
Different segments have different mechanical properties tailored to their functions. The middle cannula is locally flexible to navigate tissue curves, while the inner element is locally rigid to resist deflection and maintain reliable trajectory. This local quality differentiation resolves the contradiction between ease of navigation and reliability.
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 allows for precise and safe navigation of surgical tools within the brain, minimizing collateral damage and ensuring the tip follows a well-defined trajectory, enhancing the accuracy and safety of neurosurgical procedures.
Implementation Method 1
a self-straightening inner element disposed within said second cannula, said inner element having a flexibility such that it passes through said second cannula even when said second cannula is bent, but adopts its straight form after exiting said second cannula
Data Source
Figure 1A
Figure 1B~1D
Figure 2A~2C
AI summary
Systems comprising a needle assembly configured to be inserted and steered within the brain, body tissue, or cavity, for the purpose of performing a surgical procedure. The needle assembly comprises robotically controlled and motorized concentric cannulas. For bending, there may be provided, for example, a tensioning wire configured to bend an inner cannula, or a cannula with an adjustable natural curve. A flexible inner element passing through the bend of the inner cannula is made self-straightening to minimize susceptibility to displacement from its intended path as it is advanced through the tissue. The self-straightening inner element comprises, for example, at least one of a super-elastic tube, a shape-memory alloy tube, a slotted tube, a tightly coiled memory alloy spring, circular links held together by pulling cables preloaded by springs, and a notched inner cannula with a cable connected via a loaded spring to tension the inner cannula.