Printed and flexible electronics (PFE) signal the arrival of future omnipresent intelligent environment

Rajesh Uppal January 14, 2019 Electronics & EW, Manufacturing Comments Off on Printed and flexible electronics (PFE) signal the arrival of future omnipresent intelligent environment 1,228 Views

While the conventional electronics like computers and smartphones is built around silicon integrating billions of transistors and is manufactured using complex, costly and wasteful processes in multi-billion dollar foundries . The printed and flexible electronics aim to replace this by “organic” semiconductors which are long chains of thousands of repeating molecules (a plastic), made with materials based on carbon. Organic semiconductors can be made to be soluble, and can be turned into an ink.

Printing electronics is a special type of manufacturing, where electronic components, circuits, and systems are developed on a wide variety of substrates in a similar fashion as drawing text and figures on a paper, textile, and handicrafts. The difference between normal printing and printed electronics is that in printed electronics, functional material is used as ink that exhibits functionalities of insulator, conductor, and semiconductor materials, which are essential for the electronic devices. This means it’s possible to print electronic circuits, with the potential to manufacture components as fast as printing newspapers. A printer would do this by applying different inks onto the film. As the inks dried, they would turn into wires, transistors, capacitors, LEDs and all the other things needed to make displays and circuits.

Simplified processing steps, reduced materials’ wastage, low-fabrication costs, and simple patterning techniques make printing technologies very attractive when compared to standard microfabrication in clean room processes. The potential benefits of printed and flexible electronics include thinness, lighter weight, greater durability, and the ability for conformal integration. The intrinsic scalability of printing as a manufacturing process is also of great advantage; the process lends itself to production runs of an arbitrary size. The concept appears to provide a likely path to truly all-embracing electronics. Printed and flexible electronics (PFE) have potential to revolutionize multiple markets—health care, environmental monitoring, displays, human-machine interactivity, energy, communication, and wireless networks.

The potential uses for Printed Electronics are endless: custom electronics for smart packaging, smart wearable devices in conformal shapes, and sensors incorporated in the design of buildings, cities, cars, airplanes and just about any other device. Interest in sensors has become more prevalent due to the interest in the Internet of Things, autonomous cars and many other applications. Wearables are another area of growth. Meanwhile, RFID is growing rapidly and new possibilities are emerging in the health and wearables space. Printed Electronics will give people a low-cost, efficient way to embed intelligence into all products and objects surrounding us. That’s why Printed Electronics are paving the way for the “Internet of Everything,” and are capturing the hearts and minds of our Innovation researchers and scientists.

Printed and Flexible electronics have already started to appear in our daily lives, for example in car manufacturing with printed aerials, smart textiles with pressure sensors to recognize seat occupancy and self-dimming rearview mirrors, or in the medical field with medical test strips with diagnostic electrodes. Engineers at the University of California San Diego have developed a flexible wearable sensor that can accurately measure a person’s blood alcohol level from sweat and transmit the data wirelessly to a laptop, smartphone or other mobile device.

Researchers at the University of Tokyo have developed “optoelectronic skin”, with an ultra-thin, flexible LED display that can be worn on the back of your hand. China has developed a new electronic paper, heralded as “the world’s first graphene electronic paper,” by Chen Yu, general manager of Guangzhou OED Technologies. The material can be used to create hard or flexible graphene displays, used in electronic products such as e-readers and wearable smart devices.

Printed and flexible electronics

“Flexible Electronics” refers to electronic devices that can be bent, folded, stretched or conformed regardless of their material composition without losing functionality”. Printing on flexible substrates allows electronics to be placed on curved surfaces, for example, putting solar cells on vehicle roofs. This stretchable electronic “skin” could placed over an aircraft fuselage or a body to create a network of sensors, processors, energy stores, or artificial muscles, but it is difficult to make electronic interconnects and strain sensors that can stretch over such surfaces.

The potential benefits of printed and flexible electronics include thinness, lighter weight, greater durability, and the ability for conformal integration. The intrinsic scalability of printing as a manufacturing process is also of great advantage; the process lends itself to production runs of an arbitrary size. The concept appears to provide a likely path to truly all-embracing electronics. Printed and flexible electronics (PFE) have potential to revolutionize multiple markets—health care, environmental monitoring, displays, human-machine interactivity, energy, communication, and wireless networks.

“We are entering the age of the intelligent environment, which requires sensors everywhere to manage energy consumption, detect the presence of people, or handle the cold chain for food,” said Ian Cayrefourcq, director of Emerging Technologies at Arkema, a partner company of the CNRS. To date, this proliferation of intelligent sensing has been hampered by the cost, weight, size, form factor, and power consumption of electronic system components and boards that are manufactured using conventional techniques.

“PFE would allow intelligence will be taken out of the “boxes” or packages associated with traditional electronics like PCs, smartphones and tablets, and transplanted directly onto a variety of surfaces (including the human body), enabling an entirely new breed of defense and commercial applications unlike anything previously seen or imagined,” said Dr. Thompson in his talk.

Printed and Flexible (PFE) Electronics has arrived: International Competition

Circuit boards rolled into cylinders, for example, can provide a more efficient use of space than stacks of flat rigid boards, distributed sense and respond capability can provide structural health monitoring for building or airframes.

Japan, South Korea, and Taiwan have numerous large industrial groups with extensive manufacturing capabilities in sectors directly relevant to the production of flexible electronic devices, including microelectronics, optoelectronics, printing, electronic materials, photovoltaics, and displays.

China has developed a robust indigenous liquid crystal display (LCD) industry which it is using to leverage market entry in organic light-emitting diode (OLED).

Department of Defense Secretary Ashton Carter visited Silicon Valley to awarded NextFlex $75 million in federal funding and announce a cooperative agreement to establish this Manufacturing Innovation Institute. The U.S. is to some extent playing catch up.

“The European Union alone has spent about 200 million euros in printed electronics technology in addition to funding from national programs,” Raghu Das, chief executive of IDTechEx said. Indeed the United Kingdom has spent about $70 million on its Center for Process Innovation, Canada has spent about $40 million on a center in Ottawa and other national efforts are running in Sweden, France and several Asian countries, Das said.

At the Seoul National University in Korea researchers have created a highly flexible electronic patch capable of doing basic ECG monitoring while amplifying and storing the data locally within novel nanocrystal floating gates. The patch is made of a flexible and stretchable silicon membrane on top of which gold nanoparticles are placed so as to draw the conductive components. This eliminates conductive films that have their unique limitations while increasing the memory capacity of the device.

In IDTech event, Qualcomm showed a printed electronics label that will gather data from a golf club to deliver feedback on a player’s game to his smartphone. Thin-film battery maker Blue Spark Technologies showed a child’s bandage that can deliver temperature information to a parent’s handset, and another company showed a vest that uses printed electronics to send information about a baby’s respiration and sleep.

Printed/ Flexible sensors built on ultra-thin (less than 150 μm) polyester foils

The Imec Holst Centre has developed several P/F sensors, including a solid-state, ion- selective electrode for monitoring pH, Cl, Na and K. Additionally, they are developing sensor labels built on ultra-thin (less than 150 μm) polyester foils that can measure humidity, temperature, chemicals, and gases and include NFC/RFID functionality.

Northeastern’s Center for High-rate Nanomanufacturing (CHN) has developed a simple and highly sensitive multi-biosensor containing semiconductor single-walled carbon nanotubes (SWCNTs) that are enzyme- immobilized for detecting D-glucose, L-lactate, and urea in sweat .

CHN’s director, Prof. Ahmed Busnaina, notes that, “The utilization of semiconducting carbon nanotubes for electric detection results in high repeatability and sensitivity. By leveraging the advantage of the carbon nanotubes’ electrical response and enzyme reaction, fast, specific, and continuous detection is achieved. Printing of nanomaterials to create the sensor results in low manufacturing cost”. VTT (www.vtt.fi) from Finland is developing large area nano-photonic chemical sensors under the EU’s Photosens Program

OLED Displays

OLED organic light-emitting diode displays are predicted to take over our screens. OLED is brighter, displays greater contrast, and allows screens to be ultra-flat (only a few millimeters), curved, and flexible OLED displays are already available. Whereas in case of LCD or LED screen, where numerous layers assembled in front of a backlit system do not allow for ultra-flat screens, OLED emits both light and color on its own, thus greatly reducing the thickness of the screen.Unlike inorganic light-emitting diodes, an OLED light can be made on large plastic sheets. This means you could use OLEDs as flexible light-emitting surfaces to create new ways of lighting rooms, that aren’t reliant on point sources such as bulbs.

OLEDs are effectively a sandwich of one or more organic semiconductors in between layers that allow different electrical charges into the semiconductor. As charges meet in the middle of the sandwich, they combine together to give out light. “The market is exploding, but the product is still expensive, due to fairly low production yields, since achieving zero defects in a screen measuring one meter in diagonal remains complicated. This also explains why OLEDs are more frequently found in smartphones,” explains Ian Cayrefourcq, director of Emerging Technologies at Arkema, a partner company of the CNRS

The tricky part is making sure the devices are durable. OLED pixels can be destroyed by even trace amounts of water vapor and oxygen, so you have to seal the display within robust, high-quality, flexible materials. This is costly, and there are challenges with ensuring that the seal survives being bent hundreds or thousands of times over the lifetime of a device.

Flexible, Foldable and Rollable Displays

Foldable screens can change the way users interact with their phones. Samsung’s flexible screen phone and LG’s rollable TV can be the game changers. It will give users access to much bigger tablet-sized screens in the same form-factor. Users can use the entire screen to run content that requires a bigger screen, or use the two screens to run separate content pieces for multi-tasking. While LG’s rollable TV is still a concept, Samsung’s flexible smartphone may arrive very soon.

Chinese firm BOE has developed a 7.56 inch foldable active-matrix organic light-emitting diode (AMOLED) display, which can bend 100,000 times without breaking. Huawei is expected to use these screens in its phones. China’s Royole showed a wearable with a flexible OLED screen. Taiwanese firm AU Optronics Corp. has developed a 5 inch AMOLED display, which bends more than 1.5 million times without breaking.

The South Korean electronics manufacturer, intends to use the Plastic OLED (P-OLED) display for its upcoming flexible smartphones and tablets. Plastic OLED as the name suggests is made out of plastic substrate. LG says that unlike LCD and glass OLED displays, Plastic OLED has simple structure, and is thinner and lighter. While glass displays are prone to breakage, Plastic OLED, which is film based, is flexible enough to be curved to a certain angle, and it does not break easily, according to LG’s Display unit. LG announced that it will invest One Trillion Won ($900 million) to build a flexible OLED display plant in Korea. This will be for a Gen 6 line with production starting in 2017.

Flexible and printed Solar cells

The first generation solar photovoltaic revolution has been based on polycrystalline silicon solar cells – which are hard-wired and framed as the original ‘solar cells’. The technology underpinning such 1G cells is the p-n junction transistor; the panels are manufactured in complex semiconductor processes that call for high temperatures and close manufacturing control.

A second generation of solar PV utilized various ‘thin film’ processes where a thin film of photosensitive material is deposited on glass, such as gallium arsenide (GaAs) or CIGS (cadmium, indium, gallium and selenide). These 2G solar cells can extract more energy from the sunlight depending on the number of films utilized, to produce hybrid or tandem cells – but they are subject to the same 1G constraint of needing to be deposited on glass, a major cost and flexibility constraint.

Now a range of 3G solar cells are able to overcome this constraint by utilizing non-silicon based photosensitive materials and being printed on polymer sheets (plastic) which makes them light, flexible and low-cost. The outstanding contenders in this emerging 3G solar cell field are firstly the inorganic cells made from perovskite materials (abundant, cheap, but not yet sufficiently stable for mass utilization) and secondly organic polymer cells, where the photosensitive material is based on carbon molecules, such as those utilizing the fullerene lattice.

Polymer solar cells have in recent years emerged as a low cost alternative to silicon solar cells. In order to obtain high efficiency, fullerenes are usually required in polymer solar cells to separate charge carriers. However, fullerenes are unstable under illumination, and form large crystals at high temperatures.

Now, a team of chemists led by Professor Jianhui Hou at the CAS set a new world record for fullerene-free polymer solar cells by developing a unique combination of a polymer called PBDB-T and a small molecule called ITIC. With this combination, the sun’s energy is converted with an efficiency of 11%, a value that strikes most solar cells with fullerenes, and all without fullerenes. The combination of high efficiency and good thermal stability suggest that polymer solar cells, which can be easily manufactured using low-cost roll-to-roll printing technology, now come a step closer to commercialization, said Feng Gao.

Organic photovoltaics have a very similar structure to OLEDs and can do the same job as the silicon-based solar panels already used across the world. The key difference is that they can be made rapidly on thin plastic sheets using established printing processes. As well as reducing manufacturing costs, this means you could stick them to virtually any surface or object for a ready-made source of power.

Super-elastic conducting fibers for artificial muscles, sensors, capacitors

Liu et al. report the fabrication of highly stretchable (up to 1320%) sheath-core conducting fibers created by wrapping carbon nanotube sheets oriented in the fiber direction on stretched rubber fiber cores. The nanotubes buckled on relaxation of the core, but continued to coat it fully and could stretch enormously, with relatively little change in resistance.

“We make the inelastic carbon nanotube sheaths of our sheath-core fibers super stretchable by modulating large buckles with small buckles, so that the elongation of both buckle types can contribute to elasticity. These amazing fibers maintain the same electrical resistance, even when stretched by giant amounts, because electrons can travel over such a hierarchically buckled sheath as easily as they can traverse a straight sheath.”

By adding a thin overcoat of rubber to the sheath-core fibers and then another carbon nanotube sheath, the researchers made strain sensors and artificial muscles in which the buckled nanotube sheaths serve as electrodes and the thin rubber layer is a dielectric, resulting in a fiber capacitor. These fiber capacitors exhibited the unrivaled capacitance change of 860 percent when the fiber was stretched 950 percent.

By including other rubber and carbon nanotube sheath layers, we demonstrated strain sensors generating an 860% capacitance change and electrically powered torsional muscles operating reversibly by a coupled tension-to-torsion actuation mechanism. It could lead to super-elastic electronic circuits, robots and exoskeletons with great reach, morphing aircraft, giant-range strain sensors, and failure-free pacemaker leads.

Market Growth

The global printed electronics market size was almost $30 billion in 2017 and a growth potential to over $70 billion in ten years. The surging demand for the flexible electronics at low manufacturing costs and the need for eco-friendly technologies is paving the way for increased adoption of the technology.

Additionally, the increasing penetration of IoT worldwide is proving to be a prime factor in pulling the printed electronics market over the forecast period. The continuously growing demand for IoT in the telecommunication industry for enhancing the network and optimizing the performance along with operations is expected to propel the application of technology over the forecast period.

According to the new market research report “Printed Electronics Market by Material (Inks and Substrates), Technology , Device , Industry, and Geography – Global Forecast to 2023”, published by MarketsandMarkets™, the Printed Electronics Market is estimated to reach USD 13.6 billion by 2023 from USD 6.8 billion in 2018 in 2018, at a CAGR of 14.92% during 2018-2023. Major drivers for market growth are the rise in applications of printed electronics in IoT and significant cost advantages provided by printed electronics. The major factor restraining the market growth is the dearth of technical know-how and highly skilled system integrators.

Flexible Electronics & Circuit Market worth 40.37 Billion USD by 2023

According to the new market research report “Flexible Electronics & Circuit Market by Application (OLED & LCD Display, Printed Sensor, Battery, Thin-Film PV, OLED Lighting), Circuit Structure (Single-Sided, Multilayer, Double-Sided, Rigid), Vertical, and Geography – Global Forecast to 2023”, The flexible electronics market is expected to grow from USD 23.92 Billion in 2018 to USD 40.37 Billion by 2023, at the CAGR of 11.0% between 2018 and 2023. Flexible electronics are formed by mounting electronic devices on a flexible/plastic substrate, such as a polyimide or transparent conductive polyester film. The development of flexible electronics has spanned the past 40 years, ranging from the development of flexible solar cell arrays to flexible OLED electronics on plastic substrates. Flexible electronic devices are easier to integrate into the end product and also tend to be lighter in weight.

The increasing adoption of flexible displays in smartphones and wearables is strongly driving market growth. The emergence of flexible batteries suitable for IoT and wearable applications is a good opportunity for market growth at the global level. Samsung Group (South Korea), LG Group (South Korea), and Solar Frontier (Japan) are some of the prominent players in the flexible electronics market

Displays LCD and OLED are expected to hold the largest share of flexible electronics market during 2018–2023. The market for displays is led by industry leaders such as Samsung and LG who produce flexible OLED display panels that are largely being deployed in smartphones, smart wearables, and televisions. Leading smartphone manufacturers, such as Samsung and Apple, have adopted flexible OLED displays in their flagship smartphones. Flexible displays are also increasingly being deployed for television and digital signage applications due to their aesthetic appeal. The demand for flexible displays is expected to increase for more applications across various verticals are adopting the technology.

APAC dominated the flexible electronics market, accounting for the largest market share in 2017. In addition, the region is likely to be the fastest-growing market for flexible electronics during the forecast period. APAC is the hub for manufacturers and customers of flexible OLED panels. In the market, Samsung and LG have been the leading companies that deploy flexible displays in smartphones and televisions. In APAC, Flexible sensors are also increasingly being used for healthcare applications. APAC has witnessed an increase in the installation of thin-film PVs in the recent years, and their deployment is expected to increase steadily in China. With Japan and India being prominent countries in the adoption of thin-film PVs, other countries in the region are also shifting toward renewable energy resources.

Some of the major companies operating in the flexible electronics market are Samsung Group (Samsung Electronics and Samsung SDI) (South Korea); LG Group (LG Display and LG Chem) (South Korea); Solar Frontier (Japan); First Solar (US); Panasonic (Japan); Konica Minolta (Japan); OLEDWorks (US); Blue Spark Technologies (US); BrightVolt (US); Heliatek (Germany); Cymbet (US); Palo Alto Research Center (US); Thin Film Electronics (Norway); Royole Corporation (US); FlexEnable (UK); and Enfucell (Finland)