The expression “printed electronics” may give the impression that the technology has been around for a long time, owing to the production, launched decades ago, of printed circuit boards (PCBs), which are used in computers, TV or radio sets and many other electronic products and parts.
For its part, printed electronics (PE) consists in the creation of electronic devices and components using various printing methods, equipment and material. This technology makes it possible to produce a wide variety of products that can be used in countless applications. It has other advantages, such as a much lower production cost than conventional electronics and it can be applied to flexible or rigid supports (or substrates).
Wide range of materials
PE transforms the way electronic devices are made and employed.
Using materials (inks and substrates) that have conducting, semiconducting, non-conducting, electroluminescent, photovoltaic (PV) or other properties, and different printing methods (e.g. lithography, inkjet, or screen printing) allows great design flexibility and possibilities.
Both inorganic and organic materials are used for printed electronics. Organic materials can be found in products such as organic light-emitting diodes (OLED) displays used in televisions sets, computer monitors or mobile phones, and OPVC (organic PV cells).
Innovative materials such as carbon nanotubes allow new or enhanced applications for batteries, new types of solar cells, ultracapacitors and electrical circuits.
Engineers throughout the world use printed electronics to design a variety of components and products, such as thin film transistor (TFT), flexible displays that can be unfolded to make up a large television, PV cells that fit windows or the roofs of cars or innovative and energy-efficient lighting solutions.
In the short and medium term, hybrid systems, combining printed, flexible electronics with building blocks containing classical (silicon) electronics, will be introduced.
PE are already widely used in radio frequency identification (RFID) tags on product packaging to protect against shoplifting, to help managing stocks or to identify items during transport. They are also used in the production of flexible electronic circuits which are widespread in products where space constraints are significant, such as in small consumer electronics devices, e.g. digital cameras, mobile phones, or wearable smart devices (WSDs).
Technologies are being developed that make it possible to print electronic components, such as sensors, transistors, light-emitters, smart tags and labels or flexible batteries to power flexible and printed electronics, memory, etc.
New printed electronics applications are emerging, opening up possibilities not envisaged before. One such application is in the domain of printed batteries. More than three years ago, US scientists printed a lithium-ion battery the size of a grain of sand that could one day power tiny medical implants as well as other microelectronic devices.
From research to industrial design and to marketable products
New technologies in the printed electronics domain are emerging all the time, many are still at the research stage or under development and not ready for commercialization yet.
However, PE are being found in more and more mass-produced items, in particular in the automotive, consumer electronics and pharmaceutical industries, as well as in packaging where smart labels can provide item-level tracking of quality data for goods such as pharmaceuticals and perishable food.
The printed electronics industry currently covers five main areas:
- Lighting, including both OLED and electroluminescent (EL) products
- Organic PV
- Flexible displays
- Electronics and components, including RFID, memories, sensors, batteries and other components
- Integrated smart systems (ISS) that include smart objects, sensors like microelectromechanical system (MEMS) and smart textiles
These areas that see widespread use of PE are already covered by several IEC TCs. This led TC 119 to embark upon a series of liaisons with other TCs and external organizations.
A good example of this is the liaison with IEC TC 47: Semiconductor devices, since many of the resultant products will be hybrid devices, with both printed and conventional silicon-based components being integrated into one unit. Similarly, the liaison with IEC TC 110: Electronic display devices, makes sense as components for electronic displays are already being produced by printing, and printable materials for OLED displays are commercially available.
Taking the integration model to industry
TC 119 Chair Alan Hodgson stresses that the liaison model used by IEC TC 119 and other TCs is also of interest to industry, as systems integration across multiple horizontal technologies is seen as a significant challenge. Academic collaborators, together with their government and industrial sponsors, are seeking ways to access communities that can add value to individual technologies through integrating components upwards through the value chain. In early February 2016, the liaison structure used within the IEC was presented as a model for systems integration at a conference on Large Area Electronics (innoLAE 2016). The proposition is to build upon an existing IEC community across various technology platforms, so gathering together the stakeholders needed to work on systems integration. The concept seems to be a strong one and worthy of testing on an industrialization project.
Wearable Smart Devices
Hodgson stresses that WSDs are a category of products of high interest to PE. This is a field that provides a very good illustration of a systems integration challenge that requires input from a substantial number of horizontal technologies.
WSDs can be categorized in a variety of classes, such as “in body”, “on body” and “near body”. Of particular interest to the field of printed electronics are flexible electronic components. One example of these would be electronics printed onto textile substrates that are flexible and/or stretchable, giving rise to flexible displays integrated into garments. These could then be integrated into conformable wearable devices that could fit into everyday life in a variety of implementations.
The IEC Standardization Management Board (SMB) has recognized the potential of WSDs and the wide number of IEC TCs that have stakes in the applicable technologies. The response in 2014 was to set up an ad hoc Group, ahG 56, to review pertinent activity in the IEC in this field and to identify the needs for further standardization. The ahG 56 report resulted in the decision to start a Strategy Group, SG 10: Wearable Smart Devices, with the intention to report back to the SMB on strategy options for standardization. SG 10 has been set up with the same liaison model as described above, with representation from semiconductor devices (TC 47), assembly (TC 119), applications (TC 62: Electrical equipment in medical practice, and TC 100: Audio, video and multimedia systems and equipment) and health, safety and environment issues (TC 77: Electromagnetic compatibility, TC 106: Methods for the assessment of electric, magnetic and electromagnetic fields associated with human exposure, TC 108: Safety of electronic equipment within the field of audio/video, information technology and communication technology, and TC 111: Environmental standardization for electrical and electronic products and systems).
The health and safety aspect is of particular importance as the products will by definition be in close proximity to a human or animal. The substrates and functional materials employed must therefore of necessity be non-toxic and bio-compatible. As smart devices, they are likely to include some manner of wireless connection, so electromagnetic compatibility and safety are also important.
Even this simple overview serves to highlight some of the complex issues around systems integration, emphasizing the need for involvement of the multiple disciplines found in IEC TCs. The IEC is not the only organization looking at WSDs standardization. A Working Group of the Joint Technical Committee set by the International Organization for Standardization (ISO) and the IEC, ISO/IEC JTC 1/WG 10: Internet of Things, is also looking into this area. The challenge is to coordinate all these activities but the potential benefit in facilitating systems integration could certainly make the effort worthwhile.
The way forward
After many years, Hodgson notes, the gap between lab and fab (laboratory project to industrial fabrication) is narrowing at last. Printed electronics is ready for manufacture and integration with other technologies within the IEC family. There are significant challenges with systems integration and the knowledge available within the IEC community could be useful in helping with this, Hodgson says.
WSDs are of current interest within the IEC family. There are similar systems integration challenges within this platform of technologies and PE looks set to play its part in this.
These are both fields in which the collaboration activities across TCs could add value to industry.