The production of conventional microchips requires electronics-grade silicon, a costly material with a negative environmental impact, especially greenhouse gases. These factors limit the types of devices and everyday objects that can be equipped with silicon microchips – but perhaps not for much longer. A new type of microprocessor created entirely from paper holds the potential to bring computer intelligence into everyday objects such as radio frequency identification (RFID) tags in shipping and inventory management, and self-updating plane tickets, business cards and food labels. Invented by Portuguese scientist Elvira Fortunato and her husband Rodrigo Martins at the New University of Lisbon, the new generation of “paper chips” offer cost-saving and energy-efficient alternatives to silicon chips.
For this achievement, the European Patent Office (EPO) has named Elvira Fortunato and Rodrigo Martins as one of three finalist teams for the European Inventor Award 2016 in the category “Research”. The winners of the 11th edition of the EPO’s annual innovation prize will be announced at a ceremony in Lisbon on 9 June.
“The paper-based microchips developed by Elvira Fortunato and Rodrigo Martins have the potential to bring ‘smart’ computer technology to entirely new areas of daily life,” said EPO President Benoît Battistelli announcing the European Inventor Award 2016 finalists. “Paper-based microchips enable a new generation of inexpensive and recyclable devices that can play an important role in the Internet of Things and other digital technologies of the future.”
Paper replaces silicon
At the heart of the technology lies a technological milestone achievement: For the first time, all components of a transistor – most importantly the so-called insulating component otherwise manufactured from silicon or other inorganic materials – are crafted from cellulose, i.e. paper. Lending the transistors their electronic “spark”, key parts are coated with nanofluids containing tiny inorganic-oxide particles. This mix of materials not only makes the chips inexpensive to produce but also entirely disposable and recyclable.
Found in virtually all of today’s electronic and networked devices, transistors are the “brain cells” of electronics. Printed onto the surfaces of silicon chips, they are tiny switches that employ small electric currents to switch on other currents in their network. The idea of printing transistors on a paper surface, instead of the conventional silicon wafer, is not new. But so far, non-paper electronics had been merely embedded on cellulose fibre. In a landmark achievement, Fortunato and her team became the first inventors to incorporate paper as a functional part of transistor-based devices. To achieve the breakthrough, Fortunato, along with fellow researcher Rodrigo Martins, coat a sheet of paper with a semiconductor made of inorganic oxides – namely oxides of zinc, gallium and indium – which are then connected through a layer of aluminium. As a consequence of this nanofilm coating, the paper itself becomes not only the substrate of the transistor, but also the dielectric layer – its insulating component. The result is a full-fledged cellulose-based transistor. However, paper-based transistors are not expected to replace their much faster silicon equivalents any time soon. Their talents lie in the realm of lower-tech computing applications such as self-updating paper displays featuring electronic ink.
“Of course electronic paper won’t replace everything that’s being done with silicon technology today. But electronic paper can be used in addition to existing technologies – for low-cost applications that need to be produced in large quantities,” says Fortunato.
“Smart” electronics for one-time use
The invention marks a blue-sky moment in what could potentially become a new market for disposable objects with microchip intelligence – in other words, smart and networked devices that can be discarded and recycled after use. The technology paves the way for such futuristic devices as animated billboards and newspapers, as well as self-updating business cards and food labels. Scientific applications include biosensors, radiofrequency identification (RFID) tags in shipping and product inventory management, not to mention disposable electronics made from recyclable paper. In the bigger picture, the rise of paper-based transistors might also alleviate some of the environmental burden of silicon – the production of which releases greenhouse gases like sulphur hexafluoride – and boost the European cellulose market, which accounts for 30% of the world’s total production.
Head of Portuguese think tank
Fortunato completed a degree in Materials Science and Physics with a specialisation in Microelectronics at the New University of Lisbon (UNL) in Portugal in 1987. After receiving her PhD in Microelectronics and Optoelectronics from UNL Lisbon in 1995, she pursued her ongoing focus on inorganic oxides, a field in which she is considered one of the pioneers. Since 1998 Fortunato has served as the director of the Materials Research Centre (CENIMAT) at UNL, a renowned think tank with strong ties to the Portuguese start-up scene and government-funded research initiatives on the national and international level. Having advanced the use of inorganic oxides in electronics more than perhaps any other scientist, Fortunato secured a EUR 2.5 million grant for her work from the European Research Council, the largest ever awarded to a Portuguese scientist.
Bridging the gap between research and industry
In 2008, Fortunato’s work on the invention of paper transistors caught the attention of Portuguese augmented reality technologies firm YDreams, which tasked CENIMAT with turning paper into an interactive surface for electronics, with the European Commission providing most of the funding. That same year, YDreams secured the name Paper-e for Fortunato’s paper transistors as a trademark valid in at least a dozen countries. Listed as inventor on some 40 granted patents and 20 pending patents, Fortunato is an advocate of bridging the gap between research and the market. In terms of market applications, the most promising area for cellulose-based transistors is in the electronic smart packaging market, which third-party analysts expect to reach EUR 1.51 billion by 2022. Paper-based microelectronics also hold the potential to create an entirely new category on the lucrative global transistors marketplace, currently estimated at EUR 4.21 billion with a projected increase to EUR 10.56 billion by 2021.
Source: European Patent Office
See more, including a video describing the research, here.