Russian scientists develop new way of manufacturing flexible electronics
Source: Sputniknews 14.12.2023
Researchers from the Tomsk Polytechnic University (TPU) have teamed up with an international group to work out a method to develop conductor patterns for the surfaces of various plastic polymers covering flexible electronics.
Flexible electronics (also referred to as flex circuits) belong to a general class of electronic devices that can be bent, flexed and rolled. Flexible electronics (FE) include simple conductors, as well as electronic devices and sensors, such as on-body sensors.
According to the scientists, developing flex circuits as a technology will make it possible to create organic-based composite materials with the addition of reduced graphene oxide (rGO), which in turn will increase its overall conductivity. The results of the study are published in the Polymers scientific journal.
The practical application of such elements has a lot of potential in manufacturing medical and sports-focused devices. Plus, some industrial sensors may also benefit from integrating flex circuits. For example, organic light-emitting diode displays (OLEDs), and electronic skin with built-in pressure and temperature sensors that are used for prosthetics and robotics. The researchers noted that all these practical areas share FE implementation.
Currently, FE have not been widely used due to their challenging manufacturing process (the materials have to be mechanically stable, but plastic at the same time). However, there are several available options to reduce production costs, such as printing, solution and photolithographic methods. However, each polymer substrate requires careful optimization.
TPU-Scholar - together with their Chinese and Austrian colleagues - have developed a near universal method for processing any thermoplastic polymers in order to create FE elements. Since electrical conductivity is the key feature for such parts, the researchers have proposed a way of increasing it by introducing rGO particles into polymers through laser radiation.
"We used eight distinct polymers to create conductive polymer-based composite materials, including polyethylene terephthalate (PET), nylon, and polyvinylidene fluoride (PVDF). Most of them are used for 3D printing, which is why our technology makes it easier and cheaper to manufacture FE elements even on complex devices, compared to the existing ones. Besides, they will be more reliable," said Prof. Evgeniya Sheremet from the TPU’s Research School of Chemistry and Applied Biomedical Sciences.
There is an exciting opportunity when it comes to the thermoforming process (i.e. changes in the shape of the device once the conductive layer is fully formed). The scientists illustrated this using the example of a conductive wristband attached to a wearable smart watch.
Thus, they were able to prove the validity of the proposed approach that features introducing graphene-based conductive particles into the polymer structure via laser, and its further thermoforming.
"We have selected laser parameters for each particular polymer and have shown that the phase transitions and the degradation temperatures of the polymers determine the success of the approach. The precise selection of radiation characteristics is important not only for maintaining the integrity and consistency of the underlying material, but also in order for the graphene oxide to reduce. If successful, we get a FE material, which does not only exhibit electrical conductivity, but also shows decent mechanical stability,” the researchers noted.
