Thinner than Paper, Yet Packed with High-Tech Power: Ultra-Fine Printed Electronics Drive Major Innovations

“There is nothing new about the kinds of printed electronics that we encounter at the stadium and in almost every area of our lives. The first functional printed electronic components and assemblies were already being used in consumer electronics and the automotive industry several decades ago. These electronic circuits – manufactured using printing technology – have now become so small, lightweight, and seamlessly integrated that they remain virtually invisible to users,” explains Professor Ralf Zichner, head of the “Printed Functionalities” department at Fraunhofer ENAS.

According to Ralf Zichner, they permeate every aspect of our daily lives. Whether you are doing the laundry, washing the dishes, cooking, flying to your vacation destination, driving on the highway to your next business meeting, or working in the office, printed components are everywhere. Their range of applications extends from household and interior accessories to the aviation and mobility industries, as well as IT infrastructure, the energy sector, and healthcare and life science contexts. “The possibilities for their use are almost as limitless as the forms they can take,” says the researcher. This is because these flexible and reliable electronic solutions can be implemented almost anywhere: as circuit traces in keyboards, cable harness segments in vehicles, antennas and diodes in consumer electronics, or batteries, sensors, and heating elements, among other things.

Efficient and Resource-Conserving: Innovative Electronics with Outstanding Benefits

The secret behind what makes printed electronics so attractive to many of these industries is their unique DNA, the researcher explains: “While the production of traditional electronic circuits requires complex, resource-intensive processes – such as photolithography, etching, metallization, and many other steps – the additive manufacturing of printed and flexible electronics is much more efficient. For example, printing technology can be used to produce a highly conductive circuit trace within just a few minutes and in a single step. Another advantage is that they do not have to be produced in an ultraclean environment. In addition, significantly less material is required for their production because time-consuming intermediate steps – such as the use of etching chemicals to pattern printed circuit boards – are eliminated entirely, with the conductive structures applied directly. This speeds up production processes, conserves resources, and improves the environmental footprint.”

But that is not nearly all. The ability to apply electronics to virtually any substrate material, geometry, or surface using state-of-the-art printing processes such as inkjet, screen printing, and dispensing techniques is opening up entirely new possibilities for combining design and technology. “Highly flexible, bendable, and ultra-thin polymer films, as well as rigid or elastic substrate materials, can all have conductive layers applied to them. However, even 3D objects and unusual geometries can be equipped with electronic structures and additional functions. This opens up previously unimagined opportunities for innovation and integration in the field of printed electronics. As a result, even the smallest installation space can be exploited to the full and electronics can be incorporated into areas that were previously unsuitable for traditional circuits, allowing for entirely new aesthetic design concepts,” explains Ralf Zichner.

Furthermore, the application of printed structures is not limited to highly stretchable and elastic materials that adapt perfectly to the contours of objects and can, for example, flexibly hug the body. Rather, they can also be easily combined with traditional rigid silicon components – which is why the term printed, flexible, hybrid electronics is often used. 

Printing at Its Finest: Electronics for the Ultimate Live Soccer Experience

Soccer fans may soon be able to feel these innovations in the stadium, even if they cannot see them. An application example from Fraunhofer ENAS demonstrates how even unusual 3D objects with challenging geometries and smooth surfaces can be equipped with printed conductive structures. “Printed heating elements underneath the shells of stadium seats ensure that stadium-goers don’t have to worry about getting cold even on chilly days and can fully enjoy the live atmosphere at sporting events. Their seats can be heated within seconds – much like heated car seats,” explains Fraunhofer researcher Ralf Zichner. In addition, integrated RFID (Radio Frequency Identification) components make it possible to pinpoint occupied seats in the stadium so that the heating is only activated for those seats. In turn, this reduces energy costs and conserves resources.

Fueling Imagination and Innovation: Printed Elements for Aesthetic and Functional Interior Design Combined with Immersive Sound

The use of printing technologies to produce electronic components on flat and non-planar surfaces or 3D objects offers interesting possibilities for many applications and sectors. “Beyond the events industry, you need look no further than your own car. The heated seats provide cozy warmth, making driving more enjoyable during the cold season. The electric heating elements integrated into the seating surfaces can be manufactured using printing technology. At the press of a button, comforting warmth spreads evenly across the surface within seconds. The same applies to the rear window defroster. Here, the electric heating wires can be printed directly onto the rear window. Because they are so fine, they don’t obstruct the view and ensure a clear line of sight on frosty winter days,” clarifies Ralf Zichner.

In addition, other functional electronic elements produced using printing technology can further enhance the driving experience and, among other things, fill the car with immersive surround sound. “Printed circuit traces – such as those integrated into a car door – not only blend in aesthetically with the vehicle, but can also power the built-in speakers, thereby contributing to a first-class audio experience while driving. The same applies to many sensor technologies and touch-controlled features in cars. Physical switches and buttons can be replaced by smart, printed electronics, including those on the dashboard. They are highly functional, integrate seamlessly into the interior design, and control the infotainment experience,” explains the researcher.

Where Tradition Meets High-Tech: Functional Electronics for the Ore Mountains Festival of Lights

Researchers at Fraunhofer ENAS recently demonstrated how design, form, and function can form a cohesive whole, even in the realm of craftsmanship. To illuminate a traditional wooden candle arch, they replaced conventional power and signal cabling with extremely thin printed conductive structures. “These structures can be printed directly onto the inner and outer surfaces of the arched elements or onto the base, and equipped with various light sources,” explains Ralf Zichner.

Since the conductive elements can be printed directly onto the wooden components of the candle arch, there is no longer any need to mill the separate recesses traditionally required for cable routing. This eliminates the additional steps for creating cable channels. At the same time, the printing of conductive structures opens up far greater creative freedom in lighting design with illuminated accents – and not just when it comes to traditional Ore Mountain craftsmanship.

Precious Metal Nanoparticles: High-Tech Made from Conductive Ink

Ink plays a key role in producing printed conductive features of this kind. It consists of tiny particles of precious metals – such as silver or gold – ranging in size from 10 to 100 nanometers. “The electrical conductivity of the structures we produce varies depending on which precious metal particles are incorporated into the ink. For example, silver has the highest electrical conductivity of all precious metals. The intended application of the printed electronics and the desired properties of the printed product determine which substrate should be used, its surface characteristics, the appropriate printing process, and the choice of ink – and thus the conductivity of the printed components,” the researcher notes.

While certain inks are supplied by specialized partners, Fraunhofer ENAS develops unique inks specifically for the production of hydrogen-based systems. These contain nanoparticles of either the precious metal platinum or iridium dioxide and are used in the production of catalyst-coated membranes (CCMs) and membrane electrode assemblies (MEAs) for use in water electrolyzers and fuel cells. “This gives us a unique selling proposition as an institution. The inks we have developed are unparalleled and are based on a globally unique formula,” emphasizes Ralf Zichner. Their specific composition means that they can be printed directly and contactlessly onto a membrane, thereby functionalizing it.

For this, the researchers use specialized printing techniques such as inkjet printing. This creates the desired printed pattern in just a few minutes based on a predefined design template – with no contact whatsoever and with pinpoint accuracy. Print speeds of up to 10 meters per minute are achieved at a droplet ejection rate of 20,000 fine droplets per second. At this rate, an industrial inkjet print head with, for example, 1,280 nozzles ejects 25.6 million droplets per second, enabling extremely fast print speeds. 

After printing, the structures produced in this way – for example, those made of silver – are not initially electrically conductive. “After printing, the metallic nanoparticles are arranged side by side. It is only the subsequent drying process – also known as sintering – that causes the particles to fuse together through heating, giving them their final, conductive form.”

In this way, Fraunhofer ENAS is able to produce structures with ultra-thin layer thicknesses ranging from 250 nanometers to 30 micrometers, which is why the components produced like this are also referred to as thin-film electronics. “A comparison illustrates just how tiny the printed electronics we can create actually are: For example, a tiny bacterium is 300 nanometers in size, while a single human hair has a diameter of about 50 micrometers," the researcher points out.

The scientist is convinced that conductive functional structures on this scale will play a decisive role in shaping our future. This is because increasingly compact high-tech innovations rely on small, lightweight circuits that must adapt flexibly to the smallest of installation spaces. Printed electronics are a key driver that will significantly influence this development in the coming years.

Research and Development Services for Printed Functionalities

Fraunhofer ENAS is your partner for research and development services in the field of printed, flexible, and hybrid functionalities. Using state-of-the-art printing technologies, we can create electrically conductive functional structures and complex elements on virtually any object or surface – regardless of geometry or contour.

Our portfolio of services includes custom electronic component design, selection of the ideal ink, determination of the optimal printing process, customized substrate pre-treatment, optimized post-treatment of printed layers, and characterization of printed functional layers and designs. That is how we transform your visions into tailored solutions for your unique challenges.

Our offering in detail:

• Adaptation of printing technologies, including the selection of materials and process technologies for producing printed solutions
• Analysis of ink printability using specific printing technologies
• Printing tests, such as
  • Cleanroom-free, continuous roll-to-roll, and sheet-fed processes | Screen printing, inkjet printing, and dispensing
  • Printing onto 3D objects using inkjet printing and dispensing processes
• Transfer of knowledge relating to existing printing technologies for functional printing (web- and sheet-fed printing), including their fields of application and implementation
• Design of printed components and production of demonstrators, such as
  • Catalyst-coated membranes (CCMs)/membrane electrode assemblies (MEAs), circuit traces, electrodes, antennas, batteries, sensors, resistors, transistors, capacitors, diodes, or protective coatings
• Development of product and circuit designs, including the prototyping of printed, flexible, and hybrid electronics
• Characterization of printed functional layers with regard to their surface and electrical properties, for example by means of
  • Micro-X-ray fluorescence (µXRF), scanning electron microscopy (SEM) analysis, tactile profilometry, 4-point measurement, measurement of current-carrying capacity or high-frequency properties
• Characterization of printed components, such as
  • Catalyst-coated membranes (CCMs)/membrane electrode assemblies (MEAs), circuit traces, electrodes, antennas, batteries, or resistors
• Placement of SMDs (surface-mounted devices) on printed circuit boards

Would you like to learn more about Fraunhofer ENAS’s printing technologies and their potential to drive high-impact innovation? If so, we look forward to hearing from you.