Sustainability, material innovation and high-security design in credit card format

The debate on the future of cash has for years been characterised by an apparent contradiction: whilst digital forms of payment are gaining in importance worldwide, physical money remains essential for economic stability, financial inclusion and informational self-determination. Particularly in times of growing cyber risks, geopolitical tensions and increasing dependence on digital infrastructures, cash is once again gaining strategic importance as a resilient, autonomous means of payment.

Against this backdrop, Bundesdruckerei GmbH presents the “STELLA” concept banknote – an approach that goes far beyond traditional banknote design. The sample note from the EX NIHILO series, unveiled at the Banknote Conference in Washington, D.C., is not merely an aesthetic study, but a technological laboratory of the future for materials research, sustainability, security architecture and new forms of physical authenticity.

In doing so, STELLA takes a radical approach: maximum functionality with minimum use of materials. The banknote has been reduced to credit card size and combines innovative security features with a production concept consistently geared towards sustainability.

Cash between digitalisation and resilience

The central question behind STELLA is of a strategic nature: what role can physical money play in the future within an increasingly digital economy – and how must a banknote evolve to remain relevant in the years to come?

This consideration is by no means theoretical. Whilst the digitalisation of payment transactions is advancing worldwide, crisis scenarios regularly highlight the limitations of purely digital systems. Power cuts, cyberattacks, geopolitical conflicts or disruptions to critical infrastructure highlight that cash continues to serve as an independent fallback option.

From the perspective of many central banks, physical money therefore remains a central component of state sovereignty and societal resilience. Added to this are aspects such as data protection, anonymity and the possibility of financial participation independent of digital platforms or technical infrastructure.

Bundesdruckerei positions STELLA precisely within this area of tension. The aim is not to view physical money as a relic on the way out, but as a transformative infrastructure of security and trust that must continue to evolve technologically.

EX NIHILO: A radical redefinition of the banknote

STELLA is part of the black concept series EX NIHILO. The Latin term means ‘from nothing’ and describes the series’ fundamental design approach: rethinking the future of physical banknotes in the context of increasing dematerialisation.

The very first concept note, IGNIS, attracted international attention back in 2024. The entirely black banknote experimented with previously unconventional material and security concepts, including a black substrate and the integration of digital functions via ultra-thin chips.

STELLA consistently takes this approach further, but shifts the focus more strongly towards sustainability and resource efficiency. In doing so, it not only streamlines the design but also questions the entire material and production logic.

The basic idea: if cash is likely to be used less frequently in future, yet must simultaneously meet the highest standards of security, durability and counterfeit protection, smaller, more robust and resource-efficient formats could make more economic and ecological sense.

Credit card format instead of the classic banknote

Particularly striking is the drastic reduction in the size of the banknote to just 85 × 54 millimetres – exactly the size of a credit card.

This step has several dimensions. On the one hand, the smaller format significantly reduces material usage. Less substrate means lower raw material consumption, reduced energy expenditure in production and potentially lower transport and logistics costs.

On the other hand, miniaturisation necessitates a complete redefinition of banknote security architecture. Traditional security features usually require large areas. With STELLA, these functions had to be integrated into a very small space without compromising security or user-friendliness.

It is precisely here that the project’s true technological achievement lies: security design is no longer understood in additive terms – i.e. placing security features on an existing surface – but rather in an integrative way. The security functions themselves become the fundamental design principle.

Sustainability as a constructive design logic

A central focus of STELLA is the sustainability of the banknote’s entire life cycle.

The sample note is printed on a newly developed polymer substrate made from renewable, non-fossil raw materials. The material was developed in collaboration with industry partners and is intended to be fully recyclable. At the same time, it retains the high durability that is crucial for modern banknotes in circulation.

In doing so, Bundesdruckerei addresses a growing tension within the security printing industry: the balance between maximum durability and the lowest possible environmental impact.

Whilst traditional cotton substrates are established but resource-intensive, polymer banknotes are widely regarded as a more sustainable alternative due to their longer circulation life. STELLA now expands this concept to include bio-based raw materials and a further reduction in material usage.

However, the sustainability strategy does not stop at the substrate. Printing inks, production processes and energy consumption were also examined from a resource perspective. The reduced surface area not only cuts down on substrate consumption but also reduces the need for inks, drying energy and production time.

Security architecture in the smallest of spaces

Perhaps the greatest challenge was to fully integrate modern security features despite the reduced surface area.

To achieve this, Bundesdruckerei developed a so-called “edge-to-edge” concept. Security features are specifically positioned along the edges and, in some cases, continue across multiple areas. This creates a security logic that encompasses the entire banknote body.

The integrated technologies include several sophisticated security and authentication features from international partner companies.

Particularly striking is the use of transparent windows in combination with special optical effects. The central window of the banknote acts as a miniature projector: when light is shone behind the note, a special lens structure projects an image onto the surface beneath. This feature combines design, holography and optical security in an unusual way.

Added to this are diffractive security features, UV-active structures, infrared functions and special pigments with colour-shifting effects. In some cases, completely new printing techniques had to be developed for this purpose.

“Printing Light”: When light itself becomes a security feature

A particular technical challenge arose from the black base substrate of the EX NIHILO series.

Conventional banknotes are typically based on reflective, light-coloured surfaces. Black surfaces, by contrast, absorb light almost completely. As a result, traditional printing inks and optical effects are only effective to a limited extent.

The developers responded with an unconventional approach: instead of using light-absorbing inks, reflective pigments were employed. The project describes this approach as “Printing Light”.

In collaboration with specialist printing partners, iridescent RGB effects were created that had previously seen little use in traditional banknote printing. As a result, security architecture is increasingly shifting towards controlled light interaction and optical dynamics.

This approach is becoming particularly significant in the fight against modern counterfeiting technologies. Whilst AI-based image synthesis and high-resolution reproduction technologies facilitate digital copies, complex physical light and material effects remain extremely difficult to imitate.

Security and accessibility

In addition to security and sustainability, STELLA also takes accessibility into account.

For visually impaired people, tactile markings have been integrated directly into the edges of the banknote. Notches and indentations are created using precise laser processes, ensuring exact positioning.

This approach is noteworthy because it does not add accessibility as an afterthought, but integrates it directly into the design.

The banknote’s customisation is also laser-based: serial numbers are perforated into the material, enabling additional security and authentication features.

Innovation platform rather than mass-produced product

It is important to note that STELLA is neither a specific banknote in circulation nor an imminently forthcoming mass-produced product. Rather, the EX NIHILO series serves as an experimental platform for researching future requirements for physical money.

Bundesdruckerei is thus pursuing an increasingly relevant approach within the high-security industry: not to view innovation projects in isolation as purely technological, but as strategic scenarios for future security and trust infrastructures.

The nomination for the “Excellence in Currency Award 2026” from the International Association of Currency Affairs underscores the international attention this approach is already generating.

Banknotes as a physical trust infrastructure

Ultimately, STELLA demonstrates that the future of physical banknotes is not determined solely by design or security features, but by their role within a hybrid economic and security architecture.

In a world of increasing digitalisation, the very material quality of cash – its physical existence, its independence from networks and its direct availability – could once again become more significant.

With STELLA, Bundesdruckerei is therefore not only formulating a technological vision for banknotes, but also posing a fundamental question: How can trust be made physically visible and verifiable in a digital society?

The answer to this could be smaller in scale than before – but significantly more complex technologically.

Infobox: Tactile Marks of the STELLA Concept Note

Tactile security features for accessibility and rapid authentication

The STELLA concept banknote integrates its tactile security features directly into the outer edges of the note. The so-called “Edge-Based Tactile Marks” were specially developed to enable visually impaired people to orientate themselves more quickly and verify authenticity. Instead of additional printed elements, STELLA uses precise laser technology to structurally treat the edges.

Features

• Laser-based engraving: Precisely cut markings directly on the edges of the banknote
• High registration accuracy: Cutting and engraving take place in the same production process
• Optimised haptics: Tactile orientation where users first feel the banknote
• Integrated security function: Combination of accessibility and counterfeit protection
• Edge-to-edge design: Security features are consistently extended right to the outer edges
• Durability: Suitable for robust polymer substrates
• Minimalist design principle: Functionality without additional material layers or structures

The tactile features form part of STELLA’s holistic security concept, which aims to combine security, sustainability and user-friendliness in a significantly reduced banknote format.