Silicone Coating Flat Penetration Force Profile
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Solution Overview
Problem
Conventional silicone coatings for medical devices, such as surgical needles, have a short pot life and require lengthy thermal curing, leading to inconsistencies and reduced lubricity over multiple uses, which affects the penetration force profile and durability.
Innovation Solution
A novel silicone coating composition with a cross-linkable siloxane polymer, a non-cross-linkable siloxane polymer, and a platinum catalyst, cured by heat and further treated with gamma radiation to achieve a flat penetration force profile and extended durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silicone coatings are applied to medical devices, then the coating provides lubricious properties, but the coating requires lengthy thermal curing and has short pot life leading to inconsistencies
Solution Approach 1:
The patent changes the chemical parameters of the coating formulation by incorporating specific cross-linking agents (alkoxysilane or isocyanate) and catalysts that enable the coating to cure at lower temperatures (40-80°C) over extended periods (1-24 hours), replacing the conventional high-temperature rapid curing process. This parameter change resolves the contradiction by allowing sufficient curing time for consistency while reducing the temperature requirement.
Solution Approach 2:
The patent introduces a dynamic curing process where the coating can be applied and then cured under controlled temperature and humidity conditions over an extended period. The formulation includes moisture-sensitive cross-linking agents that progressively cure the coating as environmental moisture is absorbed, allowing the process to adapt to production scheduling needs while maintaining consistent properties.
2Duration of action of stationary object
If conventional silicone coatings are used, then the coating can be applied, but the lubricity decreases over multiple uses affecting penetration force profile
Solution Approach 1:
The patent creates a composite coating structure by combining silicone base polymers with cross-linking agents (alkoxysilane or isocyanate) that form a three-dimensional network. This composite structure integrates the lubricious properties of silicone with the mechanical durability of the cross-linked network, resolving the contradiction between durability and consistent lubricity over multiple uses.
Solution Approach 2:
The patent replaces reliance on physical adhesion with chemical cross-linking mechanisms. The alkoxysilane or isocyanate cross-linking agents form covalent bonds that chemically attach the coating to the substrate and create an interconnected network, substituting mechanical bonding with chemical bonding to achieve durable, consistent lubricity.
3Loss of time
If rapid UV curable silicone coatings are used, then curing time is reduced, but the catalyst is difficult to use without inhibitors and pot life is limited
Solution Approach 1:
The patent introduces moisture as an intermediary that triggers the cross-linking reaction. The alkoxysilane cross-linking agents react with ambient moisture to initiate curing, eliminating the need for UV light or complex catalyst systems. This intermediary mechanism simplifies manufacturing by using a naturally present substance (moisture) to control the reaction timing and progression.
Solution Approach 2:
The coating formulation is designed to be self-curing through its interaction with environmental moisture. The alkoxysilane groups in the coating automatically react with water vapor in the air or on the substrate surface, eliminating the need for external energy input (UV light) or additional catalyst components. This self-service mechanism simplifies the manufacturing process while maintaining controllable pot life.
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 method provides a consistent and durable lubricious coating that maintains a flat penetration force profile over 100 passes, enhancing surgical efficiency and reducing the need for frequent re-coating, suitable for both robotic and minimally invasive surgical procedures.
Implementation Method 1
The coating composition contains a platinum catalyst
Implementation Method 2
cured by heat
Implementation Method 3
the cured coating on the surface of the penetrating medical device is exposed to gamma radiation for a sufficient period of time to effectively cure the coating composition
Data Source
Figure 1
AI summary
A silicone coating process that improves the durability of silicone coatings on the surfaces of surgical needles and other medical devices. The silicone coated surgical needles or medical devices produced by this process have both superior lubricity and durability for ease of repeated and successive passes through tissue. The coating compositions used in the novel process contain an excess amount of polymethylhydrosiloxane cross-linker. After curing, the process utilizes gamma radiation to treat the lubricious coatings. The coatings have improved durability and performance. The penetration performance of needles coated by this novel method remains constant and flat over at least one hundred repeat passes through tissue or tissue simulation media. This provides a consistent or flat tactile response from the needles to the hand of the surgeon during a lengthy closure process, rather than an unpredictably increasing force profile. The process is also advantageous to coat reusable instruments, robotic instruments, and instruments used in minimally invasive procedures.