Surgical Knife Unit With Projections To Prevent Sticking
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Solution Overview
Problem
Surgical knives used in instruments often stick due to tissue residue and liquids, leading to operational difficulties and increased risk of injury when reactivated after a period of inactivity.
Innovation Solution
A knife unit with a longitudinal channel housing featuring inward projections that maintain a minimum distance between the knife and the channel walls, preventing sticking and allowing smooth movement, even when tissue residues or liquids are present.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the knife is guided in a laterally curved channel without projections, then the structure is simple, but the knife tends to stick when tissue liquid is displaced into the channel and the instrument is not operated for a certain time
Solution Approach 1:
The channel is segmented into multiple sections with different cross-sectional shapes. The proximal section has a different geometry than the distal section, creating varied interaction zones that prevent tissue liquid accumulation and knife sticking while maintaining structural feasibility
Solution Approach 2:
Different sections of the channel are given different local geometric properties. The channel transitions from one cross-sectional configuration to another along its length, creating localized zones that specifically address the sticking problem without requiring complete redesign of the entire channel structure
2Productivity
If the knife is moved multiple times in longitudinal direction during use, then cutting functionality is achieved, but tissue liquid is displaced into the knife channel causing the knife to stick
Solution Approach 1:
The specially shaped channel sections act as an intermediary structure between the knife and the external environment. This intermediate geometry prevents tissue liquid from effectively contacting and adhering to the knife flanks, allowing continuous movement without sticking while maintaining cutting productivity
Data Source
AI summary
An instrument with an improved knife unit includes a flat knife arranged in a knife housing. The latter comprises a channel configured for locating the knife therein, wherein on the walls of the channel inwardly projecting projections are formed, preferably in the form of nubs, between which knife is held with play. If knife housing is made of plastic, the projections can be created in a simple manner during primary shaping. If the knife housing is made from a semi-finished product, such as a sheet part by a deformation method, for example by a stamp-bending process, the projections facing one another constricting the channel can be produced in that the walls are provided with cavities on their outer sides. The knife unit is particularly robust against contamination.