Cross-Axis Flexural Pivot Joints for Low-Friction Surgical Articulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing surgical instruments face challenges with joint mechanisms that are either too large in size, lack flexibility, or suffer from high friction and wear, limiting their effectiveness and stability, especially when reduced to diameters less than 3 mm.
Innovation Solution
The development of cross-axis flexural pivot joint assemblies that incorporate elastic flexures to allow for two degrees of freedom, reducing friction and wear, while maintaining stability and increasing the range of motion, with a design that can be scaled to smaller sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If non-compliant pin-in-slot joints are used to allow rotation between shaft portions, then mobility is achieved, but friction and wear increase leading to performance degradation
Solution Approach 1:
The patent replaces the traditional pin-in-slot mechanical joint with a compliant mechanism that uses elastic deformation of flexible members to achieve rotation. This substitution eliminates direct mechanical contact between rigid components, thereby reducing friction and wear while maintaining the desired mobility for wrist articulation in surgical instruments.
Solution Approach 2:
The patent employs flexible members with specific geometric configurations (such as curved beams or elastic elements) that deform elastically to enable rotational motion. These flexible components replace rigid pin-and-slot connections, providing smooth motion with minimal friction and no wear, thus improving reliability while preserving ease of operation.
2Length of moving object
If surgical instruments are reduced to diameters less than 3 mm to minimize incisions, then patient trauma is reduced, but flexibility and range of motion are compromised
Solution Approach 1:
The patent divides the instrument into multiple segments or links connected by compliant joints, allowing each segment to be compact while the overall structure achieves greater flexibility through articulated motion. This segmentation enables the instrument to maintain a small diameter (<3 mm) for minimal incisions while providing sufficient range of motion for effective tissue manipulation.
Solution Approach 2:
The patent introduces wrist articulation mechanisms that add rotational degrees of freedom perpendicular to the instrument's longitudinal axis. This dimensional addition allows the instrument to achieve complex motion paths and improved flexibility without increasing its primary diameter, enabling effective operation through small incisions while maintaining adaptability.
3Adaptability or versatility
If wrist articulation is added to provide flexibility and gripping function, then adaptability is improved, but the throw distance from shaft axis to end effector tip increases requiring more volume
Solution Approach 1:
The patent integrates the wrist articulation mechanism within the existing instrument shaft structure, nesting the rotational joints and flexible members inside the instrument's body. This nested configuration allows wrist articulation to be achieved without significantly increasing the throw distance or the overall volume required at the surgical site, maintaining compactness while improving adaptability.
4Reliability
If compliant mechanisms with flexible members are used to reduce friction and wear, then reliability is improved, but stability decreases and fatigue failure becomes a concern
Solution Approach 1:
The patent employs flexible members constructed from composite materials or structures that combine high elasticity with enhanced strength and fatigue resistance. These composite flexible components maintain the low-friction, wear-free advantages of compliant mechanisms while improving stability and reducing susceptibility to fatigue failure, enabling reliable operation over extended periods.
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 cross-axis flexural pivot joint assemblies provide improved flexibility, reduced friction, and increased range of motion, enabling surgical instruments to operate effectively with minimal size and operating footprint, while maintaining stability and durability.
Implementation Method 1
The flexure is configured to deform elastically when the first joint member and the second joint member move from a first configuration to a second configuration
Data Source
AI summary
The embodiments described herein can be used in a variety of grasping, cutting, and manipulating operations. In some embodiments, an apparatus includes a first joint member, a second joint member, and a flexure. The first joint member includes a first connection portion and a contact surface. The second joint member including a second connection portion. A first end portion of the flexure is coupled to the first connection portion, and a second end portion of the flexure is coupled to the second connection portion. The flexure is configured to deform elastically when the first joint member and the second joint member move from a first configuration to a second configuration. When in the first configuration, the central portion of the flexure is spaced apart from the contact portion. When in the second configuration, the central portion of the flexure contacting the contact portion.