Authors: Kyle Pilkington, Jorge Bautista
Historically, Titanium has been the material of choice, but as technology continues to evolve, we see the need for radio frequency (RF) improving communication in real time with our devices for better patient care. Wireless power transfer eliminates the need for cable management through the body and longer implantable life.
Ceramic cases continue to grow in this field due to their singular properties, including biocompatibility, non-reaction with chemicals, and strong resilience.
We will be going over the benefits of using hermetically-sealed ceramic cases as opposed to traditional titanium cases for use in implantable devices.
What is a Hermetic seal?
A hermetic seal is an airtight seal that prevents gases, liquids, and other contaminants from passing into or out of an enclosed space. In medical applications, achieving a high-quality hermetic seal is crucial to maintaining the sterility and functionality of implants. These seals are designed to withstand the harsh environments within the human body, protecting sensitive electronic components from bodily fluids and other corrosive substances. The integrity of a hermetic seal is often measured by its ability to maintain a vacuum, which is essential for ensuring the longevity and reliability of medical devices.
Why is a Hermetic seal so important?
When we place elements in living physiology, it is critical for no contamination to pass into the human body that would affect the health of the patient in question. Also, the reverse is applicable: where fluids from biological tissue would be highly corrosive for the devices, decreasing or terminating the life of the stated component.
But obtaining hermetic seals isn’t without challenges. Techniques must be adapted as electronic implants shrink. Materials selection requires balancing: durability, human compatibility, and cost.
Why Use a Ceramic Case?
Ceramic cases offer several key properties that are essential for creating effective hermetic seals:
- Chemical Inertness: Resistant to corrosion and chemical attack, ensuring long-term stability.
- Thermal Stability: Withstand high temperatures without degradation.
- Electrical Insulation: Keeping electrical signals under control and maintaining the reliability of the product.
- Mechanical Strength: High compressive strength and hardness provide durability.
- Radio Frequency: Ceramics are widely known for their ability to let Radio frequency pass through the material, unlike metals that do.
Brazing a metallic interface to a ceramic case enables the case to be welded to adjacent assemblies such as:
- Feedthroughs
- Lids
- Weldable connections
When used together they have a great symbiotic relationship.
Benefits and Applications of Brazed Ceramic Cases in Medical Devices
Ceramics alone are not practical for this application and need to be joined with a feedthrough (sealed hermetically) that will contain and complete the connection to the rest of the electronics and/or mechanisms within. Brazed ceramics with metal interfaces are crucial in various medical applications due to their excellent hermetic sealing, biocompatibility, and durability. Here are some notable benefits and applications:
- Superior Hermeticity: The combination of ceramics and metals through brazing creates airtight seals that protect internal components from moisture, gases, and biological fluids.
- Enhanced Durability: Ceramics provide high compressive strength and hardness, while brazing ensures robust metal-to-ceramic joints capable of withstanding mechanical stresses.
- Biocompatibility: Ceramic materials are biocompatible, reducing the risk of adverse reactions when used in medical implants.
- Corrosion Resistance: Both ceramics and the metals used in brazing resist corrosion, ensuring long-term stability and functionality of the implant.
- Thermal Stability: Ceramics can withstand high temperatures, and brazing provides excellent thermal conductivity, essential for managing heat in electronic implants.
Applications:
- Cochlear Implants: Brazed ceramic-to-metal feedthroughs ensure hermetic seals that protect sensitive electronic components from bodily fluids, ensuring reliable performance and longevity.
- Cardiac Pacemakers: Hermetically sealed ceramic-to-metal enclosures protect the internal electronics from corrosion and moisture, crucial for the device’s functionality and the patient’s safety.
- Neurostimulators: These devices use brazed ceramic and metal interfaces to ensure hermetic sealing, protecting delicate electronics that modulate nerve activity to treat chronic pain, Parkinson’s disease, and other neurological conditions.
- Implantable Drug Delivery Systems: Brazed ceramic-to-metal seals ensure the integrity and reliability of the drug delivery mechanism, preventing contamination and ensuring precise dosing over extended periods.
- Endoscopic Equipment: Ceramic-to-metal brazing is used in endoscopic devices to provide hermetic seals that protect internal components from the harsh environments encountered during medical procedures.
Benefits of Gold Brazing for Medical Devices
STC Hermetics is a leading expert in gold brazing of ceramic to metal. Gold brazing is a highly beneficial technique for assembling medical implants, offering several key advantages that enhance the performance and longevity of these devices:
- Biocompatibility: Gold is highly biocompatible, minimizing the risk of adverse reactions when implanted in the human body. This is crucial for ensuring patient safety and the long-term success of the implant.
- Corrosion Resistance: Gold exhibits excellent resistance to corrosion, which is vital in the harsh, reactive environment of the human body. This resistance helps maintain the integrity and functionality of the implant over time.
- Thermal Conductivity: Gold’s superior thermal conductivity ensures efficient heat dissipation from electronic components within the implant, reducing the risk of overheating and potential damage.
- Strength and Ductility: Gold brazing provides robust joints that can withstand the mechanical stresses and strains encountered in the body. The ductility of gold also allows for some flexibility, accommodating movement without cracking or breaking.
- Precision and Reliability: The brazing process allows for precise joining of small and delicate components, which is essential for the intricate designs of modern medical implants. The reliability of gold brazed joints contributes to the overall durability and effectiveness of the device.
By incorporating gold brazing in the manufacturing of brazed ceramic cases, STC Hermetics can achieve high-quality, durable, and safe devices that meet the rigorous demands of medical applications.
The Role of STC Hermetics in Advancing Brazed Ceramic Cases
STC Hermetics has been at the forefront of developing advanced brazed implantable ceramic cases and hermetic seals for medical applications. Examples of successful material combinations used for implantable ceramic cases are:
- Titanium to zirconia (via gold & active braze)
- Titanium to alumina (via gold)
- Titanium to sapphire (via gold)
- Stainless steel to sapphire (via silver)
- Stainless steel to alumina (via CuSil)
- stainless steel to glass (via AuSn)
By leveraging the expertise and innovative capabilities of STC Hermetics, the medical industry can continue to develop advanced implants that improve patient outcomes and meet the growing demands for high-quality medical devices.
Conclusion
Implantable ceramic cases are revolutionizing the field of medical implants, offering unparalleled benefits in terms of biocompatibility, durability, and functionality. As research and innovation continue to advance, ceramics will play an increasingly critical role in the development of next-generation technologies, improving performance, reliability, and patient outcomes across multiple industries.
By embracing ceramics, industries can address the growing demand for reliable, long-lasting, and biocompatible materials, ensuring the success and sustainability of their applications in the future. The contributions of companies like STC Hermetics further enhance these advancements, providing the industry with the expertise and innovative solutions needed to create the most effective and durable medical devices.