Research carried out by Manuel Reis Carneiro, a Ph.D. student from the Carnegie Mellon Portugal Program (CMU Portugal) at the Faculty of Science and Technology of the University of Coimbra (FCTUC) and Carnegie Mellon University (CMU), developed a conductive ink-based of water for the production of flexible electronic circuits that avoid the use of organic solvents, which are pollutants and harmful to the environment. The technique has just been published in the scientific journal Advanced Science.
Because it is produced with water, this paint is more sustainable, and ecological and significantly reduces the environmental impact of existing solutions. Electronic stickers for monitoring health or ensuring the quality of food products are some of the possible uses.
Manuel Reis Carneiro, PhD student from the CMU Portugal Program and researcher at the Institute of Systems and Robotics (ISR) at the University of Coimbra, is part of a team led by Mahmoud Tavakoli, who already has extensive experience in the development of flexible electronic circuits. Producing these circuits easily, quickly and economically has been one of the main challenges for the Coimbra team, which is now taking a new step in this direction by developing a paint that is sustainable and environmentally friendly.
«The use of a water-based ink for the printing and production of flexible electronic circuits brings numerous advantages. On the one hand, it radically reduces the ecological footprint of production because it does not use polluting materials. On the other hand, it makes recycling and subsequent reuse of circuits much easier, which previously consisted of a complex procedure. In this case, simply place the circuit in alcohol, the components and metallic particles separate and are ready to be reused», explains Manuel Reis Carneiro.
Another great advantage is that this paint, unlike the previous ones, does not have to be refrigerated, it can be kept at room temperature for around a month, which facilitates its preservation, reduces the ecological footprint and maintenance costs.
Currently, these flexible circuits have several applications, especially in the health sector as biomonitoring sensors and adhesives capable of recording patients’ health data, namely muscle activity, breathing, body temperature, heartbeat, brain activity, or even emotions. Most medical devices used in hospitals, namely electrodes for electrophysiology, are single-use and wasted after one use. Therefore, the introduction of this new ink, which allows easy and economical recycling, has a relevant impact on the reuse of monitoring stickers, significantly reducing electronic waste, also known as e-waste, generated by single-use solutions.
The food industry is another sector that can benefit from this discovery by integrating it into the next generation of smart packaging. The team tested the application of this new ink on stickers that can be printed on plastic and applied to perishable food packaging, to monitor their temperature and guarantee their quality. This way it is possible to guarantee adequate preservation, record any problems that occur during storage, and inform the consumer.
«For now, the stickers created feature a temperature sensor that measures the temperature (TºC) of the packaging and warns the user when there is a risk of contamination. This solution has a low production cost, so in the future, it will be viable to include these stickers in the packaging of perishable goods to control their quality. At the moment, it is possible to monitor the temperature of the packaging and exposure to unfavorable conditions, but we hope to be able to control other factors such as pressure, humidity, position, or location in the future», he reveals.
The FCTUC ISR team has made significant progress in the area of production of flexible electronic circuits, in order to make the production of these solutions viable in terms of costs and on a large scale. It is now possible, for example, to produce these circuits using only a traditional 3D printer, and last year, an alternative was presented for the integration of microchips, in solid state, in flexible materials, and circuits based on elastic polymers.
The production of water-based conductive paints and reducing the environmental impact of electronic waste is another step towards the team’s goals. «As the world becomes increasingly dependent on electronic devices, it is crucial to recognize and address the environmental challenges presented by the new waste created. Therefore, we intend to develop innovative electronic systems based on flexible electronics, with several advanced functionalities and applications in both medicine and industry, but always taking into account sustainability, resource efficiency, and a minimum environmental impact», he concludes.
The scientific article “Recyclable Thin-Film Soft Electronics for Smart Packaging and E-Skins” can be consulted here.