Trigger Lock Mechanism for RF Tissue Sealer Safety
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Solution Overview
Problem
Existing electrosurgical instruments face challenges in preventing accidental cutting and ensuring safe operation, particularly in maintaining the jaws closed until the knife is fully extended and retracting it before opening, while also requiring secure RF energy activation only when the jaws are fully closed.
Innovation Solution
The design incorporates a trigger lock mechanism with a switch arm and a compression circuit that prevents the jaws from opening until the knife is retracted and ensures RF energy activation only when both the energy button and compression circuit are activated simultaneously, utilizing a pull ring for knife operation and a lock spring for neutral positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trigger lock mechanism is implemented to prevent accidental cutting, then safety is improved, but device complexity increases
Solution Approach 1:
The trigger lock mechanism is designed to automatically engage the locked state before the cutting sequence can be initiated. The switch arm is positioned and configured to prevent trigger activation until the jaws are fully closed, thereby performing the safety check in advance and preventing accidental cutting before it can occur.
Solution Approach 2:
The switch arm serves as an intermediary mechanical element between the jaw closure mechanism and the trigger activation system. It translates the jaw closure state into a lock/unlock signal, mediating the interaction between these two functions and enabling the trigger lock mechanism to operate based on jaw position without direct electronic sensing.
2Reliability
If the jaws are locked closed until the knife is fully extended, then cutting safety is improved, but operation time increases
Solution Approach 1:
The knife extension mechanism is designed to begin its extension sequence immediately upon jaw closure, with the switch arm automatically engaging the locked state at the appropriate moment. This preliminary action ensures that the knife is already extending or fully extended by the time the jaws need to remain locked, minimizing the duration of the locked state without compromising safety.
Solution Approach 2:
The trigger lock mechanism incorporates dynamic elements including a spring-loaded switch arm that can rapidly transition between locked and unlocked states. The spring mechanism allows for quick engagement and disengagement of the lock, reducing the time the jaws remain constrained while maintaining the safety requirement throughout the critical cutting phase.
3Reliability
If RF energy activation requires simultaneous pressing of energy button and compression circuit activation, then safety is improved, but ease of operation decreases
Solution Approach 1:
The compression circuit activation is designed to occur automatically as a preliminary action when the jaws are closed on tissue. This automatic activation removes the need for the operator to manually press both buttons, as the compression circuit engages itself based on the jaw closure state, while still maintaining the safety requirement that both energy and compression are activated.
Solution Approach 2:
The system is designed to self-activate the compression circuit based on the mechanical state of the jaws. When the jaws close sufficiently, the compression circuit automatically engages without requiring additional manual input from the operator, thereby simplifying the operation while maintaining the dual-activation safety feature.
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 configuration enhances safety by preventing accidental cutting and ensuring that RF energy is applied only when the jaws are securely closed, allowing for controlled tissue sealing and cutting.
Implementation Method 1
a second jaw comprising an electrode operable to deliver radio frequency (RF) energy to tissue
Data Source
AI summary
A variety of surgical instruments include one or more elements that transmit RF energy to tissue. Some such instruments comprise a pair of jaws that open and close on tissue, with conductive tissue contact surfaces that are operable to weld tissue clamped between the jaws. Some surgical instruments also include a translating tissue cutting element. Some such instruments may be in the form of forceps having a scissor grip. Forceps type instruments may in some instances provide a feature that allows the jaws of the forceps to be locked on tissue, so that the operator can remove his or her hands from the instrument. In such an instrument it may also be desirable to provide a circuit that is activated only when the forceps are closed and sufficient pressure is applied to the tissue between the jaws of the device.