Sutureless Lamination for Covered Scaffolds Engineering the Interface Between Fabric, Membrane, and Metal

In covered stents and other scaffold‑based implants, device performance is often dictated by a single, easily overlooked detail: how the cover is attached to the scaffold. The interface between fabric or membrane and metal must withstand crimping, delivery, expansion, and long‑term cyclic loading, while maintaining a low profile, predictable mechanics, and reliable sealing.

Traditionally, this interface has been addressed using mechanical or thermal workarounds such as sewing, sintering, or dip‑coating. While proven, these methods impose fundamental design and manufacturing constraints. Medibrane’s sutureless lamination technology was developed to remove those constraints by bonding fabrics and membranes directly to scaffolds instead of sewing them, using an adhesion‑driven approach rather than mechanical fixation.

Traditional Methods for Attaching Covers to Scaffolds

Sewing Fabric to Stents

Sewing is one of the oldest and most widely used methods for attaching fabric to metallic stent frames. In this approach, the cover is fixed to the scaffold using sutures placed at discrete points along the structure.

From an engineering standpoint, sewing introduces several inherent limitations:

• Discrete load transfer: Mechanical loads are concentrated at stitch locations rather than distributed across a continuous interface.

• Increased device profile: Sutures add bulk and often require thicker fabrics to tolerate stitch tension.

• Perforation of the cover: Each stitch creates a hole in the fabric or membrane, which can become a leakage pathway in sealing applications.

• High process variability: Sewing is typically manual, operator‑dependent, and difficult to scale without significant inspection and rework.

While sewing is familiar and mechanically intuitive, it fundamentally limits how thin, flexible, and consistent a covered scaffold can be.

Sintering ePTFE on Stents

Sintering is commonly used to attach ePTFE membranes to stents by applying elevated temperatures that fuse the polymer structure around the scaffold.

This method provides strong attachment, but it introduces tradeoffs:

• High thermal exposure: Elevated temperatures can affect scaffold properties and restrict material combinations.

• Limited local control: Fine tuning of thickness, compliance, or bonding patterns is difficult.

• Process rigidity: Sintering is less adaptable to rapid iteration or selective bonding strategies.

For designs that require thin walls, controlled flexibility, or mixed materials, these constraints can be limiting.

TPU Dip‑Coating

Dip‑coating involves immersing a scaffold into a thermoplastic polymer solution to form a continuous coating.

While dip‑coating eliminates stitches and avoids high temperatures, it has its own limitations:

• Thickness variability: Coating uniformity is inherently harder to control.

• Increased stiffness: Dipped layers often add radial strength and reduce compliance.

• Limited design resolution: Selective bonding, patterned attachment, or partial sealing are difficult to implement.

Dip‑coating can be effective for certain applications, but it offers limited precision for complex covered scaffold designs.

Medibrane’s Sutureless Lamination Approach

Medibrane’s sutureless lamination technology takes a different path. Instead of mechanically fixing fabrics or membranes to the scaffold, it chemically bonds them.

Using surface activation and a binding polymer, Medibrane enables adhesion between materials with inherently low surface energy'such as nitinol, ePTFE, TPU, and textile fabrics.

This creates a continuous bonded interface across the scaffold rather than discrete attachment points.

Importantly, this approach applies not only to polymer membranes but also to fabrics traditionally sewn onto stents, such as skirts and textile covers. These fabrics can be laminated directly to the scaffold without sutures.

Engineering Advantages of Bonded Fabric and Membrane Lamination

Continuous Load Distribution

By replacing stitches with a bonded interface, mechanical loads are distributed across the bonded area instead of being concentrated at individual fixation points. This improves uniformity during crimping, expansion, and long‑term fatigue loading.

Reduced Profile

Eliminating sutures removes both the physical bulk of the stitch and the need for thicker fabrics designed for stitch retention. This enables thinner wall constructions and lower crimped profiles—critical for minimally invasive delivery.

No Stitch Holes

Bonded lamination eliminates needle perforations in the cover. In sealing applications, this removes a known source of leakage and improves confidence in circumferential sealing performance.

Selective Bonding and Design Freedom

Unlike sewing, sintering, or dipping, sutureless lamination supports selective bonding:

• Partial or patterned bonding regions

• Tunable balance between fixation and flexibility

• Control over local compliance and loading force

This allows engineers to design covers that seal where needed while remaining flexible elsewhere.

Scalability and Repeatability

Sutureless lamination is designed as a non‑manual, repeatable process. Compared to sewing, it reduces touch time and operator variability, supporting tighter process control and more predictable scale‑up.

Comparison of Covered Scaffold Attachment Methods

Method	How it Works	Interface Characteristics	Impact on Profile	Design Flexibility	Manufacturing Characteristics	Typical Limitations
Sewing fabric to stents	Fabric mechanically fixed with sutures	Discrete contact points, point‑load transfer	Increased due to sutures and thicker fabric	Very limited	Manual, high touch time, operator‑dependent	Stitch holes, higher profile, variability
ePTFE sintering	Heat‑driven fusion of ePTFE to scaffold	Strong attachment, thermally constrained	Moderate	Limited	High‑temperature process, rigid	Thermal impact on scaffold, limited tuning
TPU dip‑coating	Scaffold immersed in polymer solution	Continuous coating, variable thickness	Moderate to high	Limited	Simple but low precision	Thickness variability, increased stiffness
Sutureless lamination (Medibrane)	Chemically bonded fabric or membrane via surface activation	Continuous bonded interface	Reduced	High (selective bonding, partial sealing)	Non‑manual, repeatable, scalable	Requires adhesion engineering upfront

From Textile Mechanics to Adhesion Engineering

The core shift enabled by sutureless lamination is not just the removal of stitches,it is a shift from textile mechanics to adhesion engineering.

Instead of designing around the constraints of sewing, sintering, or dipping, engineers can tune interfaces at the material level, controlling where and how the cover is attached to the scaffold. This opens new design space for covered stents, valve skirts, and functional catheter structures.

Summary

Sutureless lamination is more than an alternative attachment method. By bonding fabrics and membranes directly to scaffolds, it enables:

• Lower device profiles

• Improved mechanical uniformity

• Enhanced sealing performance

• Greater design freedom

• Manufacturing processes built for scale

For OEM engineers developing the next generation of covered implants, rethinking how covers are attached to scaffolds can unlock performance gains that are difficult—or impossible—to achieve with traditional methods.