Non-Linear Jaw Cam Slots for Consistent Surgical Grip Force
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Solution Overview
Problem
Existing minimally invasive surgical instruments face challenges in applying sufficient gripping forces to handle, seal, or cut tissue and vessels of varying sizes due to linear cam slots that provide inadequate mechanical advantage at angles greater than 20 degrees, leading to inconsistent force output and sensitivity to input changes.
Innovation Solution
The design incorporates non-linear cam slots in the jaws of surgical instruments, ensuring a substantially proportional force application throughout the actuation stroke, providing a constant mechanical advantage regardless of jaw angle, allowing for consistent gripping force across different tissue sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If linear cam slots are used in the jaws, then the structure is simple and easy to manufacture, but the mechanical advantage is inadequate at angles greater than 20 degrees, resulting in insufficient gripping force
Solution Approach 1:
The patent applies curvature by replacing linear cam slots with non-linear (curved) cam slots in the jaw structure. The curved cam slots are specifically designed to provide a substantially constant mechanical advantage throughout the actuation stroke, enabling consistent grip force application regardless of jaw angle. This directly resolves the contradiction by using geometric curvature to improve force output while accepting increased structural complexity.
2Reliability
If linear cam slots are used, then the device is easy to operate, but the force output is inconsistent and sensitive to input changes, particularly for larger vessels
Solution Approach 1:
The curved cam slot geometry is specifically engineered to maintain a constant mechanical advantage ratio throughout the actuation stroke. This curvature design ensures that the output grip force remains proportional and consistent relative to the input actuation force, reducing sensitivity to input variations and providing reliable force application for vessels of varying sizes.
3Force
If non-linear cam slots are implemented, then consistent gripping force is achieved throughout the actuation stroke, but the manufacturing complexity increases
Solution Approach 1:
The non-linear cam slots are designed with specific curved geometries that can be manufactured using standard precision machining techniques. The curvature is engineered to provide the desired constant mechanical advantage property, balancing the need for improved force characteristics with manufacturability considerations.
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
This design enables surgical instruments to apply a consistent gripping force, enhancing tissue handling and sealing capabilities, particularly for larger vessels, by maintaining a constant mechanical advantage throughout the actuation range, thus improving the reliability and effectiveness of minimally invasive procedures.
Implementation Method 1
The non-linear slot is shaped such that a grip force applied by the jaw is substantially proportional to a force applied to the pin to translate the pin through the slot (i.e., the ratio between the input force and the resulting output force remains substantially the same as the pin travels through the slot)
Data Source
AI summary
A surgical instrument includes an end effector with opposing jaws that open and close relative to each other. The jaws each include a cam slot for receiving a cam pin. Translation of the pin through the cam slots opens and closes the jaws. The cam slots are shaped such that at least one of the jaws applies a grip force that is substantially proportional to a force applied to the pin to translate the pin through at least a portion of the slots (i.e., the ratio between force input and the resulting force output remains substantially the same as the pin travels through at least one portion of the slots). This design provides a constant mechanical advantage between the force applied to the pin and the force applied by the jaws, thereby allowing a user to more easily regulate the forces applied to tissue held by the jaws.