Introduction
Medical device industry consist of a wide range of products and technology, these products are applied for diagnosis, mitigation, treatment, compensation, and prevention of disease and other conditions.
The primary materials of medical device fabrication include silicone and latex. These two materials are thermoset plastic, both materials get permanent shapes by a chemical reaction. However, each material also has distinctive performance and applications.
Bio-compatibility is the most important characteristics of materials for medical devices manufacturing. It ensures device’s ability of functional performance without undesirable side effects. Generally, bio-compatibility including several factors:
- Physical attributes as rigidity and surface smoothness,
- Chemical nature as allergenic or toxic,
- Body reaction and effect on product function,
- Once in evaluation of latex and silicone properties for medical device, we must consider various factors to get the best decision.
Silicone Medical Devices
Silicone can be molded into simple and complex shapes for ultimate usability. It is transparent, and it can resist ultraviolet light effects. Significant progress in material science provide different silicone material options: High consistency silicone (HCR), Fluorosilicone Rubber (FSR), Liquid Silicone Rubber. For applications with seals, gaskets, casings, or other critical circle components, LSR is the most popular option because of its resistance to stress, fatigue and tearing.
Combining LSR unique characteristics with high purity and chemical inertness will create truly cutting-edge silicone materials for medical device beyond skin contact. We can apply these materials for both short-term and long-term insertion inside human body. LSR is the most common silicone material in the manufacturing of medical devices, including: gaskets and o-rings, syringe stoppers, dialysis filters, infusion pumps, diaphragms, and pull rings.
LSR is not only suitable for implantable and non-implantable medical devices, but also can be over-molded. This technology combines LSR with other plastic or metal materials simultaneously, in order to create a soft-touch surface for medical electronic products.
Miwo provides special medical grade silicone to meet the demand and performance requirements of health agencies. Utilizing an internal certification process of bio-contact applications by United States Pharmacopeia (USP). Each test will certificate the bio-compatibility level of a particular silicone material, and determine the suitability application in medical, food or pharmaceutical devices.
Silicone Properties
The quality of silicone makes it an attractive latex alternative for medical devices, silicone main attributes including:
- Bio-compatibility: Odorless and tasteless liquid silicone rubber (LSR) has extreme compatibility with human tissue and body fluids. It has bacteria and mold growing resistance, and doesn’t stain or erode other materials. Medical grade silicone satisfy FDA, ISO, and Tripartite bio-compatibility requirement in medical products guidelines.
- Chemical resistance: Silicone has excellent resistance to water, ammonia, oxidizing chemicals and acids.
- Insulation properties: Silicone is suitable for various electrical applications, in reason of its strong insulation properties. Silicone has natural non-conductivity, it can maintain dielectric strength in extreme thermal environment, this surpasses latex and other materials.
- Mechanical properties: LSR has high tensile strength, magnificent elongation, superior flexibility, and low compression set. Its hardness range from 5 to 80 Shore A.
- Thermal resistance: Comparing to other elastomer materials, silicone is stable within temperature from -24℃ to 260℃. Multiple methods can be applied for sterilization, such as: EtO gas, gamma or E-beam irradiation, steam autoclaving.
Liquid Injection Molding
Liquid injection molding has shorter molding cycles comparing to transfer molding and compression molding, in reason of its higher operation temperature and pressures. LSR molding is the future of silicone industry because of its cleanliness and speed factors.
In LSR injection molding process, two liquid component of LSR are pumped into the mixer with homogeneity, then mixed materials flows into the mold cavity and undergoes high temperature. This process is a closed process with quick turnaround. So it has a minimal contamination chance with consistent quality. There is a summary of LSR molding benefits:
- High processing performance,
- Rapid cure rate,
- Less cycle time,
- Lower production cost,
LSR molding is suitable for complex designs with large volume in automated system. It will increase the production efficiency.
LSR Applications
Advances in material and injection molding technologies improve the manufacturing of medical devices in medical/healthcare industry. Silicone is a safe latex alternative, it has replaced latex for various products and devices. Low cost of silicone encourage it to create products in cost-effective way, for example: gloves, syringes, gowns and many other products.
Liquid silicone rubber is not only the optimal material for medical devices manufacturing, but also widely applied in other industries. Such as: aerospace, automotive, bio-pharmaceutical components, computer components, construction, food and beverage devices.
Medical devices’ approval include stringent regulations requirements in national and international. This will ensure the safety of products for paints and healthcare workers. So it is critical to ensure your team can understand the intricacies of material selection.
Latex Medical Devices
Latex is a natural thick colloidal suspension with milky-white color. It is popular in the form of latex rubber gloves. Finished latex material has excellent flexibility, it can withstand bending, elongation or pulsating forces.
Over these years, we apply latex to produce a wide range of medical devices and products. Such as: stethoscope tubes, surgical gloves, diaphragms, endotracheal tubes, band-aids, adhesive taps, blood pressure cuffs, rubberized bedsheets, anesthesia and oxygen masks. However, the increase of latex usage also give rise to the rise of latex allergies.
Primary Latex Molding Method
Normally, the mandrel has required shape and size of products. It will be dipped into a coagulant solution like calcium nitrate, then immersed into a container with prepared liquid latex material. After that, we will set the mandrels into ovens or other heating system to complete the coagulation process. Then water spraying is applied to clean coagulant and other additives.
Next, the coagulated parts will go through a vulcanization process. After next water washing, we should apply different methods to prevent sticking, such as powder lubricants or chlorination. In order to increase products thickness, we just need to repeat dipping process into latex.
Cost Comparison of Silicone versus Latex
Silicone materials are more expensive than latex. However, other factors must be considered in the decision-making process for medical devices’ production.
For example, silicone catheters not only improve patient’s comfort level, but also have positive effects on other factors than latex catheters:
- Fewer incidents of allergic response.
- Less phlebitis occurrence.
- Lower sepsis frequency.
- Lower risk of bacterial migration.
- LSR medical devices reduce the potential of infections and expensive liability cost.
For more information about latex vs silicone, contact our engineering team now.
