Plastic Electronics represents a new branch in the electronic field which is focused on the production of displays on plastic surfaces. This new technology provides lighter and more flexible devices making their incorporation into certain articles easier or even allowing the development of big displays which roll up or fold on themselves. On the other side, it is a cheap technology.
The “Plastic Electronic” displays which are going to be developed within the project are:
- Electrooptics, which use an electric field to provoke a different optical effect.
- Flexible Tactile Switches, to replace all kind of keys and buttons by contact areas within the same piece.
- Flexible Plastic Electronic Circuits, which will avoid the use of cables and welding.
According to the book titled “How the Toy and Game Industry will be Transformed by Printed Electronics”, the lastest developments undertaken in this field will notably increase innovation, competitiveness and the sustainability of the sector.
On the other side, according to another study undertaken by IDTechEX, an exceptional income increase in the “plastic electronics” sector is being forecast, which will rise from $1.92 billion in 2009 to $57.16 billion in 2019.This data is an indicator of the vast potential that plastic electronics have for companies which invest in this field.
In the initial phase of the Project, it was determined that for the correct integration of an electrochromic display, it must be able to switch between a high number of cycles, the time needed to make the change between coloured and transparent must be a matter of seconds, the material must give a good contrast to the human eye and the display must operate at a reduced voltage (between 0 and 5V, 10 mA).
In the following project phase the selection, adaptation and synthesis of materials with electro-optical properties were carried out, as well as the assembly of the devices and the initialization of their characterization.
- Electrochromic: CIDETEC’s research in this Project spans from the organic materials synthesis with electrochromic properties to the device assembly on plastic substrate, as well as its integration into prototypes. In the current Project framework, moreover, the synthesis and characterization of 3 new electrochromic derived substances based on selenophen and pirrol were carried out. At first, the synthesis of these new monomers gave the materials electrochromic capability to change colour between orange and black. Later on, the incorporation of substitutives in polymers of this type led to multi-chromic behaviour achieving 5 different colours.
Generally, an electrochromic device is made up of 7 layers. Nevertheless, the intention of the present project is to reduce the number of layers used and make a formulation which includes the electrochromic material, the electrolyte and the re-dox couple of the electrochromic material, passing from 7 layers to 5. Recently, Cidetec has developed its own electrochromic formulation with a polymeric base, which notably simplifies the production process of these devices (which reduces the number of active layers from 3 to 1).
- PDLC: “Polymer Dispersed Liquid Crystals” technology, is based on the dispersion of a liquid crystal in a polymeric matrix. The difference between the liquid crystal’s refraction index and the polymer produces a high light dispersion (scattering) which makes the material change its appearance from translucent to whitish. When a film of this type of material is situated between two transparent electrodes and an alternating current (AC) is applied, the appearance changes from translucent (OFF status) to Transparent (On Status) in milliseconds due to the orientation of the liquid crystal molecules parallel to the electric field orientation.
CIDETEC efforts are mainly focused on the improvement of the displays, optimizing factors such as transparency and contrast and the development of displays which operate in reverse, this is to say, which are transparent in the OFF status and translucent in the ON status. Until now, composites have been made using a mixture of pneumatic liquid crystal and different polymeric matrices, varying parameters such as the composition and the phase separation, which have allowed the production of small displays (upto 3x4 cm2) which operate in the correct way, both in plastic and crystal substrate.
- Electroluminiscentes Displays: CETEMMSA’s contribution to the Project includes the design, selection and synthesis of materials with electroluminescent properties and the assembly of the devices going through the different deposition techniques of the active materials. Additionally, they will also work on the characterization of electroluminescent displays and their later integration into toy prototypes.
In the Project Framework, inorganic EL displays are being developed by means of screen-printing using both different geometries, on a transparent and non-transparent substrate. The emission colours can vary between white, green, orange and blue and the development of the organic displays will be tested by means of ink-jet.
- Flexible Tactile Switchers and Flexible Circuits: CETEMMSA will work on the design and production of Flexible Tactile Switches with two different types of structure (single layer and multiple layer structure) and two different types of technology (capacitive and reactive).
In the established design, two electrodes will be deposited, in the case of the capacitive sensor to achieve a higher level of sensitivity, and in the resistive case, it will have only one electrode or two, if considered necessary.
Electronic circuits will be printed which will act as the connection between the different displays. So, inks based on silver, nickel or copper, among others, will be used or conductor polymer based inks, deposited using ink-jet techniques.
AIJU’s Guide of Play and Toys (aiju.info) has been used to undertake a study of the toys that will greatly improve with the ‘Plastic electronics’ insertion, trying to stress the interactions that children would have with it. In a first approximation the following possibilities where wondered: cuddly toys’ and dolls’ eyes, blankets, children’s carpets, Twister style games, tables, baby-walker trays, high chair trays, games platform, electrical instruments, toy cars, toy kitchens, puzzles, magic games, physics and chemistry games, complements (glasses, visors and peaks, bracelets, necklaces...), luminous games, etc.
The final selection of prototypes in which “Plastics electronics” will be introduced will depend on the results derived from posterior analysis. Finally, all the tests established by the Toy Safety standards will be undertaken.
The development and application of ‘plastic electronics’ in the toy sector will suppose quite an important technological innovation, both on a national and international scope. The new devices developed in the present project on flexible plastic substrates and the use of new materials that will replace traditional electronics, will not only involve relevant innovation regarding materials but offer a range of new possibilities for innovation in the design of new toys. The results of this project will allow the toy sector to apply important technological innovations far more rewarding than the design innovations that are periodically achieved, being able to make, in the medium term, a big technological and competitive step with regards to other competitive regions. In 2009 and 2010 the research in this project will be carried out with the aim of accomplishing the planned objectives.
We would like to acknowledge the Science and Innovation Ministry for the financial support it has granted to this Project.
We would also like to ask toy manufacturers or users interested in the integration of these devices if they would fill in the questionnaire on the Project Website.