Innovating Medical Device Stents with Nitinol and Advanced Materials: How Lumenous Device Technologies Leads the Way

The medical device industry has witnessed significant advancements in recent years, particularly in the development of stents, which are critical in minimally invasive surgeries for treating vascular diseases. In the mid-1990s, the term stent was used almost exclusively to refer to a cylindrical mesh structure that was expanded in an artery or other body lumen (passageway) to keep the lumen open. As innovation spread across the body, the term stent was applied more liberally to similar structures that have other purposes.

One material that has revolutionized the stent industry is Nitinol, a unique metal alloy known for its extraordinary properties. Nitinol’s superelasticity and biocompatibility make it the versatile champion material of choice for stents, offering patients improved outcomes through minimally invasive procedures.

However, Nitinol is not the only material used in stent development. A range of materials and coatings, including stainless steel, cobalt-chromium alloys, titanium, and various polymers, are commonly used to address specific clinical requirements and optimize stent performance.

At Lumenous Device Technologies, we are proud as industry pioneers to press on at the forefront of innovation in stent design, development, and manufacturing. Our commitment and experience enables us to guide customers through the entire life cycle of their stent devices, from initial concept and design to full-scale manufacturing and beyond.

Here’s a look at the materials and coatings used in stent production and how we leverage these technologies to create the best possible products for patients.

Additionally, we help streamline the development of delivery devices for stents, ensuring a complete and efficient process from design to deployment.

Nitinol: The Material of Choice for Stents

Nitinol, an alloy composed of nickel and titanium, is renowned for its unique mechanical properties that make it ideal for use in medical devices, particularly stents:

• Superelasticity: Nitinol can return to its original shape after being deformed, making it perfect for stents that need to overcome difficult access challenges or recover after deformations without permanently changing shape. It also enables a stunning variety of potential shapes after implantation or during temporary deployment.
• Biocompatibility: Nitinol is highly compatible with human tissue, minimizing the risk of adverse reactions and increasing the long-term success rate of stent implants.

These properties have made Nitinol the material of choice for a wide range of stent applications in passageways throughout the body.

Because of Nitinol's superelasticity, no balloon is used to expand them once inside the body. Instead, the stent is held inside a sheath until arriving at the location of treatment. Then the sheath is retracted, and the stent expands to engage the vessel wall.

Fun Facts:

1. An innovative California startup engaged the Lumenous design team to produce a balloon-expandable nitinol stent. The stent's thermal history was managed to keep the stent in the plastic-deformation range when at body temperature - no superelastic behavior. It actually worked, and the client company was acquired at a handsome price.

2. In a remarkable twist, a European company engaged the Lumenous design team to design a balloon-expandable superelastic stent - which seems like an oxymoron. By exploiting critical ratios of strut widths and carefully designed strut joints, the stent remained in the superelastic state but was able to achieve large expansions and small delivery diameters. The technology was profitably sold to a rising star company, but its clinical development was sidelined after a subsequent acquisition.

Therapeutic Applications of Stents in the Body

Stents are versatile medical devices that are used in various parts of the body to treat a wide range of health conditions. The main therapeutic application of stents is in the cardiovascular system, but their use has expanded to other areas as well:

• Coronary Artery Stents: One of the most common uses of stents is in treating coronary artery disease. These stents are implanted to keep narrowed or blocked coronary arteries open, improving blood flow to the heart and reducing the risk of heart attacks.
• Peripheral Artery Stents: Stents are also used to treat peripheral artery disease (PAD), which affects the arteries in the legs and arms. These stents help to restore blood flow in peripheral arteries, preventing tissue damage and alleviating symptoms like pain and numbness.
• Carotid Artery Stents: In cases of carotid artery disease, where there is a risk of stroke due to blockages in the arteries supplying the brain, stents can be used to open up the narrowed carotid arteries, reducing the risk of stroke.
• Renal Artery Stents: Renal artery stents are used to treat renal artery stenosis, a condition that can cause kidney damage by restricting blood flow to the kidneys. The stents help restore blood flow and prevent kidney failure.
• Biliary and Esophageal Stents: Stents are often used in the bile ducts and esophagus to treat obstructions caused by tumors or other blockages.

These therapeutic applications highlight the broad utility of stents in improving patient outcomes across multiple medical disciplines, from cardiovascular to gastrointestinal and beyond.

Other Materials Used in Stent Manufacturing

While Nitinol is a top choice with exceptional versatility, there are several other materials used in stent design to suit different needs:

Stainless Steel

Stainless steel, particularly 316L stainless steel, has been widely used for stents due to its excellent strength, flexibility, and resistance to corrosion. It is a cost-effective option and has been successfully used in coronary and peripheral vascular stents. By now, it has generally been replaced by other materials.

Cobalt-Chromium Alloys

Cobalt-chromium alloys offer high strength, radiopacity (allowing visibility in imaging), and corrosion resistance. These alloys have largely displaced SS316L and enable thinner stent designs, which improve deliverability and also reduce the risk of restenosis (re-narrowing of the artery). Cobalt-chromium is often used for high-performance stents, such as drug-eluting stents (DES).

Biodegradable Stents

Biodegradable or bio-absorbable stents are made from biocompatible polymers or metal alloys (including magnesium, for example) that degrade naturally in the body after a certain period. These stents bring potential advantages for cases where long-term implantation is not required, leaving behind no permanent implant once the healing process is complete. The polymer bioresorbable approach burned brightly for a time but then dimmed and flamed out. The metal bioresorbable approach remains available and under development.

Stent Coatings; Enhancing Performance and Safety

Stent coatings are crucial for improving the biocompatibility, reducing the risk of blood clots, and enabling drug delivery. Here are the most commonly used coatings in stent manufacturing:

Drug-Eluting Coatings (Drug-Eluting Stents - DES)

Drug-eluting stents are coated with drugs that are slowly released to prevent restenosis. Several drugs are used in DES, which help prevent the overgrowth of smooth muscle cells inside the artery. These stents are particularly important in coronary artery stenting, reducing the need for repeat procedures. The drugs are incorporated into biodegradable coatings.

Biodegradable coatings are made from materials that degrade naturally in the body, offering the benefit of releasing therapeutic agents, such as anti-inflammatory or antiproliferative drugs, before safely disappearing over time. These coatings are often used in biodegradable stents, which provide the required support to the artery while eventually breaking down to avoid leaving a permanent implant. Some of polymeric biodegradable coatings include polyethylene glycol (PEG), polyvinyl alcohol (PVA), and polylactic acid (PLA/PLGA).

Heparin Coating

Heparin is an anticoagulant that helps prevent blood clot formation around the stent. By applying heparin coatings to stents, the risk of thrombus formation may be addressed.

Silicone Coating

Silicone coatings are applied to stents to perform various functions including perfusion or filtration.

Carbon Coatings

Carbon-based coatings, such as diamond-like carbon (DLC), have been used to enhance the wear resistance and friction properties of stents. These coatings may improve durability and ensure long-term performance of the stent in the body.

Streamlining the Delivery Device (Catheter) Development for Stents

In addition to the stent itself, the development of a reliable delivery device is essential to the successful implantation of stents.

We recognize that the delivery system is just as important as the stent, ensuring its accurate placement and proper deployment inside the body.

The Role of Delivery Devices

Delivery devices are critical for ensuring that stents are positioned precisely in the targeted area. These devices are designed to transport the stent through the vascular system and deploy it with minimal trauma to the surrounding tissues. The design of the delivery device must consider factors such as:

• Ease of Deployment: The device must ensure smooth delivery and deployment of the stent with minimal force, reducing the risk of complications.
• Minimally Invasive: The delivery device should be compatible with minimally invasive techniques, such as catheter-based procedures, to minimize patient recovery times.
• Precision: Accurate placement of the stent is critical to achieving the desired therapeutic outcome. The delivery device must allow for controlled release and positioning of the stent.

How Lumenous Device Technologies Can Help

We offer end-to-end support in developing both stents and their accompanying delivery devices. Our team is equipped to handle the entire development process, from concept to production, ensuring that both the stent and delivery device function together seamlessly.

• Device Design: Our experienced engineers and designers collaborate closely with clients to create delivery devices that are optimized for their specific stent designs. We utilize advanced design tools such as CAD and finite element analysis (FEA) to ensure that the device is both effective and easy to use.
• Prototyping & Testing: We develop prototypes of stents and conduct extensive testing to ensure that they meet rigorous standards for performance, safety, and compliance.
• Full-Scale Manufacturing: Once designs are validated, we move to full-scale manufacturing using state-of-the-art production facilities. This includes laser cutting, optimized heat-treatments, electropolishing, and assembling the delivery system to ensure precision and quality.
• Regulatory Compliance: Our team ensures that both stents and delivery devices components meet all regulatory requirements, including FDA, CE, and ISO certifications, helping our clients navigate the approval process efficiently.

Lumenous Device Technologies: Leading the Way in Stent and Delivery Device Innovation

At Lumenous Device Technologies, we are dedicated to providing innovative solutions for the design, development, and manufacturing of stents and their delivery devices. Our expertise in Nitinol processing, stent coatings, and catheter-based delivery systems ensures that we can deliver the highest quality products with unparalleled precision.

By partnering with us, clients can streamline their device development roadmap, bringing high-performance stents and delivery devices to market faster and more efficiently.

Conclusion

The development of stents and delivery devices has come a long way, driven by materials like Nitinol, cobalt-chromium, and titanium, as well as advanced coatings that improve their performance, reduce complications, and enable targeted drug delivery.

At Lumenous Device Technologies, we leverage these materials and technologies to provide high-quality, innovative stents and delivery systems that meet the needs of both healthcare providers and patients.

Whether you are at the concept stage or ready for full-scale manufacturing, Lumenous Device Technologies is here to help you bring your stent and delivery device projects to life with precision, innovation, and expertise.