Cellulose is the most abundant organic matter on Earth. What if it was used to make electronic circuits? Elvira Fortunato, materials scientist and engineer, has invented the paper-based transistor.
Elvira Fortunato not only used paper to create the transistor base, she also created the functional parts with it.
These are the “brains” of electronics. Most of our everyday devices have transistors in them; however, as they are largely made up of silicon, the production of which has a significant environmental impact, they have a negative environmental impact.
The production process is both energy-intensive and extremely wasteful: up to 80% of metallurgical silicon is lost during the purification stage required to obtain an electronic grade silicon. It also releases sulphur hexafluoride, the most powerful greenhouse gas on Earth (its global warming potential is more than 20,000 times greater than that of CO2!). Finally, the production of electronic silicon has a financial cost, in particular, due to the processing of the chemicals used.
But is this material really necessary? Portuguese teacher Elvira Fortunato thinks not. This materials scientist and engineer working at the New University of Lisbon not only used paper for the transistor base (which had already been done) but also for the functional parts, replacing silicon. She won the 2016 European Inventor Award from the European Patent Office for this innovation.
A transistor is made up of three essential components: a conductor, a semiconductor, and an insulator made of dielectric material. Silicon is used both as a semiconductor and an insulator. By coating sheets of paper with inorganic oxides connected by an aluminium layer, Elvira Fortunato and her team created an insulating cellulose-based component. The paper-based transistor that resulted from these experiments is inexpensive, energy efficient, and fully recyclable.
Conventional transistors are effectively more powerful than paper-based transistors. However, the idea is not to replace them but for the two technologies to co-exist. Paper-based microchips could be used for applications where silicon is too expensive or which require producing electronic circuits in large quantities and at a low cost, such as RFID tags for smart marking.
CREDIT: Main picture © Noémie Rosset / Veolia