Inverted Tool Member Compliant Mechanism for Surgical Instruments
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Solution Overview
Problem
Existing surgical instruments face challenges with flexibility and reduced operating footprint, often resulting in increased friction, wear, and undesirable motion due to non-compliant joint mechanisms.
Innovation Solution
The development of compliant joint mechanisms featuring an inverted tool member and a flexure that deforms elastically to allow for rotational motion relative to a shaft, reducing friction and wear while maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-compliant joint mechanisms (pin-in-slot joints) are used, then rotational motion is achieved, but friction and wear increase leading to performance degradation
Solution Approach 1:
The patent replaces traditional non-compliant pin-in-slot mechanical joints with compliant mechanism joints that use elastic deformation of flexures to achieve rotational motion. This substitution eliminates sliding friction and wear associated with conventional mechanical joints, thereby improving reliability while reducing harmful friction and wear effects.
Solution Approach 2:
The patent employs flexures (flexible elastic members) as thin film-like structures that deform elastically to provide joint rotation. These flexible members replace rigid mechanical joints, eliminating contact friction and wear while maintaining the desired rotational degrees of freedom, thus resolving the contradiction between reliability and friction/wear.
2Object-generated harmful factors
If compliant mechanisms are used, then friction and wear are reduced, but stability and resistance to buckling decrease
Solution Approach 1:
The patent segments the tool structure into multiple rigid segments connected by compliant joints (flexures). This segmentation allows each segment to be optimized for strength and stability while the flexures provide the necessary compliance. The rigid segments maintain structural stability and resistance to buckling, while the flexures reduce friction and wear.
Solution Approach 2:
The patent employs composite construction combining rigid tool segments (for stability and buckling resistance) with flexible elastic members (for low-friction motion). This composite approach allows the system to simultaneously achieve the benefits of both rigid structures (stability) and compliant mechanisms (reduced friction and wear).
3Length of moving object
If tool diameter is reduced to minimize incision size, then patient trauma is reduced, but flexibility and operating footprint are compromised
Solution Approach 1:
The patent inverts the traditional approach by placing the wrist articulation mechanism at the distal end of the tool rather than proximally. This inversion allows the tool shaft to remain thin and flexible for minimal incision access, while the distal wrist mechanism provides the necessary articulation and flexibility. The compliant joints enable this compact distal articulation without requiring a larger tool diameter.
Solution Approach 2:
The patent employs a nested structure where the wrist articulation mechanism is integrated into the distal end of the tool shaft. The compliant joints and flexures are nested within the compact tool structure, allowing complex articulation functionality to be achieved within a small diameter tool that can pass through minimal incisions while maintaining flexibility.
4Adaptability or versatility
If wrist articulation is added to tools, then tissue manipulation capability is improved, but operating footprint and volume increase
Solution Approach 1:
The patent inverts the conventional wrist mechanism design by placing it at the distal end of the tool and using compliant joints with inverted tool members. This inversion allows the wrist articulation to be achieved in a compact configuration that minimizes the operating footprint and volume required at the surgical site, while still providing full wrist articulation capability for effective tissue manipulation.
Solution Approach 2:
The patent changes the geometric parameters of the wrist mechanism by using inverted tool members and compliant joints with optimized flexure dimensions. This allows the wrist articulation to achieve the necessary range of motion and manipulation capability with reduced throw distance and smaller overall volume, minimizing the operating footprint at the surgical site.
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 compliant joint mechanisms provide improved flexibility and reduced friction, enabling effective tissue manipulation with a minimized operating footprint, while avoiding buckling and maintaining mechanical advantage throughout a wide range of motion.
Implementation Method 1
The flexure is configured to deform elastically when the actuation force is exerted on the actuation portion of the tool member such that the tool member rotates relative to the shaft
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 shaft, a tool member, and a flexure. The shaft has a distal end portion and a proximal end portion, and defines a longitudinal axis. The distal end portion includes a ground portion. The tool member has an engagement portion and an actuation portion. The engagement portion is disposed distally from the actuation portion, and can exert an engagement force on a target structure. The actuation portion receives an actuation force. The flexure has a first end portion coupled to the ground portion of the shaft, and a second end portion coupled to the tool member. The flexure is configured to deform elastically when the actuation force is exerted on the actuation portion of the tool member such that the tool member rotates relative to the shaft.