Heated Hemostatic Surgical Blade with Copper Thermal Transfer
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Solution Overview
Problem
Existing hemostatic surgical scalpel blades face challenges in delivering sufficient thermal energy to tissues for effective hemostasis while maintaining a sharp and durable cutting edge, due to limitations in thermal conductivity and durability, especially under varying surgical conditions.
Innovation Solution
The development of a symmetrical five-layer laminar hemostatic surgical blade with a martensitic stainless steel core and pure oxygen-free hard copper thermal transfer layers, supported by austenitic stainless steel buttressing layers, combined with a flexible substrate-supported heater circuit, enhances thermal conductivity and maintains blade hardness and sharpness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high thermal conductivity materials are used for the blade, then heat delivery to tissue is improved, but the cutting edge durability and sharpness deteriorate due to premature dulling from corrosive biological fluids and elevated temperatures
Solution Approach 1:
The blade is constructed as a composite structure with a core made of hard material (e.g., martensitic stainless steel or ceramic) that maintains cutting edge sharpness and durability, and an outer layer made of high thermal conductivity material (e.g., copper or aluminum) that efficiently delivers heat to the tissue. This composite design allows the blade to simultaneously achieve both effective hemostasis through heat delivery and sustained cutting performance through the durable core material.
2Reliability
If the blade is heated to greater than 400° C. for extended periods, then hemostatic effectiveness is improved, but the blade hardness and sharpness are reduced due to annealing or tempering effects
Solution Approach 1:
The composite blade structure with a hard core and thermally conductive outer layer enables the blade to withstand extended heating at hemostatic temperatures without significant loss of hardness. The core material is selected to maintain structural integrity and sharpness even when the outer layer is heated to therapeutic temperatures for prolonged periods.
Solution Approach 2:
The blade exhibits different thermal properties at different locations: the core material has lower thermal conductivity and higher hardness to maintain cutting edge integrity, while the outer layer has high thermal conductivity to deliver heat to the tissue. This spatial variation in material properties allows the blade to achieve both hemostatic effectiveness and durability during extended use.
3Temperature
If high thermal conductivity materials are used for the blade, then heat delivery to tissue is improved, but heat conduction to the handle increases making it uncomfortable for the surgeon to hold
Solution Approach 1:
The blade exhibits different thermal properties at different locations: the cutting edge region uses high thermal conductivity material to efficiently deliver heat to the tissue, while the handle region uses low thermal conductivity material to minimize heat conduction to the surgeon's hand. This spatial variation in thermal conductivity allows the blade to achieve both effective hemostasis and comfortable handling.
Solution Approach 2:
The blade structure acts as a thermal intermediary, with the high thermal conductivity material concentrated at the cutting edge where heat delivery is needed, and the low thermal conductivity material positioned at the handle to block heat transmission to the surgeon's hand. This intermediary arrangement of materials with different thermal properties resolves the contradiction between effective heat delivery and comfortable handling.
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 allows for efficient heat delivery to tissues, maintaining blade sharpness and durability during extended surgical procedures, improving hemostatic effectiveness and reducing the need for frequent handle replacements.
Implementation Method 1
a heating element proximate to the cutting edge to heat the blade
Implementation Method 2
The oppositely disposed copper layers are each bonded with a buttressing layer
Implementation Method 3
The heat is transferred from the instrument to the incised (or torn) tissue to thermally reform collagen, thereby producing a thin collagenous film that seals over the severed blood vessels and capillaries
Data Source
AI summary
A hemostatic surgical blade is described which is formed of five symmetrically disposed layers. A martensitic stainless steel core is provided with oppositely disposed faces which are bonded to hard pure copper thermal transfer layers which, in turn, are supported by buttressing layers of austenitic stainless steel. The blade is heated by a blade heater circuit which is provided as a flexible circuit carrying one or more resistor heaters and associated leads supported by a polyimide substrate. A thermally conductive and electrically insulative adhesive is used to bond the flexible circuit to a blade blank. The system employs a multi-lead cable which is removable from an instrument handle. One blade embodiment involves an elongate stem for accessing body cavities and another embodiment incorporates a controller function within an instrument handle.