Engineered interlayers boost satellite insulation and flexible electronics

by Robert Schreiber
Berlin, Germany (SPX) Dec 17, 2025

Researchers at Empa are refining the multilayer insulation foils that wrap many satellites and space probes, aiming to improve their mechanical robustness while maintaining thermal protection. These foils, known as multilayer insulation or superinsulation, are built from stacked layers of a strong polymer coated with thin metal, typically aluminum, and are also used on Earth in items such as survival blankets.

On spacecraft, this insulation shields sensitive electronics from large and rapid temperature swings in orbit. For satellites in low Earth orbit, the temperature difference between the sun-facing side and the side in shadow can reach about 200 degrees, and similar swings occur when a satellite passes into and out of Earth's shadow many times per day, even though the electronics operate best near room temperature.

The thin-film system usually relies on polyimide as the base polymer because it withstands high temperatures and vacuum and forms a stable bond with the aluminum coating. According to Empa researcher Barbara Putz, an extremely thin interlayer only a few nanometers thick forms at the interface between polymer and aluminum during coating and plays a key role in adhesion, prompting the team to study and control this interface more closely.

Putz's project, supported by an Ambizione Grant from the Swiss National Science Foundation, aims to use a deliberately engineered interlayer to improve superinsulation for future satellites and enable new flexible electronic systems on Earth. To investigate the effect of this layer, Putz and doctoral student Johanna Byloff chose a simple model: a 50-micrometer polyimide film topped with 150 nanometers of aluminum, separated by a five-nanometer aluminum oxide layer.

Working with a layer only a few nanometers thick requires precise vacuum processing, so the team uses a coating machine developed by Empa spin-off Swiss Cluster AG that can run multiple coating steps on the same sample without breaking vacuum. The material combination in their experiments matches that used in space hardware such as ESA's Mercury mission BepiColombo and the sunshield of NASA's James Webb Space Telescope.

Byloff notes that in existing space systems the intermediate layer arises naturally, whereas in the Empa approach it is manufactured explicitly, allowing its properties to be tuned. The James Webb sunshield, measuring roughly 21 by 14 meters, highlights the mechanical demands on the composite: the stacked layers had to survive being tightly stowed for launch, deploy at the destination without tearing or delamination, and withstand impacts from particles and space debris without cracks spreading across large areas.

The Empa team subjects the model films to tensile tests, thermal shock loading, and detailed chemical and physical characterization to evaluate performance. Results indicate that the artificial interlayer increases elasticity and improves resistance to cracking and flaking of the metal coating.

Next, the researchers plan to vary the interlayer thickness and transfer the concept to other polymer substrates. Putz points out that naturally formed interlayers appear only on a limited set of polymers and to thicknesses of about five nanometers, whereas the engineered version could enable stable multilayer systems on polymers that previously showed poor coating adhesion.

Beyond satellite insulation, Putz and Byloff see broad potential in flexible electronics, which also rely on metal-coated polymer films and often stack several thin layers of different materials. The controlled use of ultra-thin interlayers could improve mechanical behavior in foldable or rollable devices, smart textiles, and flexible medical sensors by helping multilayer stacks absorb deformation without failure.

Research Report:From Mechanics to Electronics: Influence of ALD Interlayers on the Multiaxial Electro-Mechanical Behavior of Metal - Oxide Bilayers