Designing Electronics for the Unreachable: Hidden, Conformal, and Embedded Paths

Unlocking Functionality on Non-Planar, Enclosed, and Internal Surfaces 

Modern engineering challenges increasingly require electronics that go where traditional PCBs can't—inside curved medical catheters, along the walls of tight aerospace enclosures, or embedded in complex 3D structures. In these scenarios, the surfaces available for routing circuits are anything but flat, and real estate is always at a premium. 

Exxelia Micropen's direct-write technology is uniquely suited to meet this challenge. By precisely depositing conductive, resistive, and dielectric materials onto virtually any surface geometry—inside, outside, curved, or flexible—we enable design teams to integrate electronic functionality where it was previously unreachable. 

Engineering Constraints: When Surface Real Estate Vanishes 

Traditional circuit layout strategies assume the presence of accessible, planar surfaces. But in critical applications—such as catheters, satellite modules, or implantable sensors—engineers must make design tradeoffs due to: 

• Limited accessibility: Internal cavities or sealed housings prevent component access post-assembly. 

• Non-planar geometries: Cylindrical shafts, balloon-expandable structures, or irregular enclosures are not PCB-friendly. 

• Extreme miniaturization: Devices are shrinking, but performance demands continue to grow. 

Direct-write electronics eliminate the need for flat substrates by turning the product itself into the circuit platform.  

Direct-Write Circuit Strategies for Complex Geometries 

Micropenning—our proprietary form of high-precision additive dispensing—lets us print fine-line features on challenging 3D surfaces. Key capabilities include: 

• Printing on thin, flexible, and highly contoured substrates including polymers, glass, metal, or ceramic. 

• 50 µm trace widths with 25 µm spacing, enabling dense layouts on tight footprints. 

• Inks engineered for electrical, thermal, or sensing functions, including conductors, dielectrics, resistors, and radiopaque materials. 

• 6-axis motion system with vision alignment ensures accurate placement even on irregular or curved geometries. 

Designers can route circuits along the walls of a catheter, wrap sensors helically around a tube, or embed thermal traces inside constrained volumes—all without adding bulk or compromising integrity. 

Medical and Aerospace Use Cases 

Medical Devices: Catheter-based systems often require sensing, heating, or visualization features within confined internal volumes. Micropen technology has been successfully used to print: 

• Radiopaque markers directly on balloon-expandable implants, eliminating the risks of swaged bands. 

• Electrodes for ablation or neurostimulation, printed onto the catheter surface to maintain flexibility and biocompatibility. 

Aerospace Systems: Weight and space constraints drive demand for components that integrate multiple functions without additional mass or volume. Direct-write circuits can: 

• Replace wired assemblies with printed resistive heating elements on conformal surfaces. 

• Enable sensor arrays on irregular structures for environmental or structural monitoring. 

Co-Designing with the Substrate, Not Against It 

Our approach encourages design teams to rethink their constraints. Instead of working around the substrate, we work with it—turning every surface into usable circuit real estate. This strategy improves: 

• Design elegance: Fewer components and interconnects. 

• System reliability: No swaged bands, fewer solder joints, and better mechanical stability. 

• Manufacturing efficiency: Prototyping and production can scale using the same direct-write approach. 

We partner with OEMs from early design to production, helping identify where embedded, conformal, or hidden circuits can enhance performance and reduce risk. 

Rethink the Limits of Circuit Design 

If your project involves confined spaces, complex geometries, or inaccessible surfaces, direct-write electronics may be the enabling technology you've been looking for. 

Micropen helps engineers integrate performance—not just on the surface, but deep within the design.