Scientists from the Tomsk Polytechnic University Research School of Chemical and Biomedical Technologies have developed a new technology for manufacturing universal flexible sensors for electrochemical analysis of substances. It is based on laser processing of graphene oxide films and silver nanoparticles on a polymer substrate. The sensors obtained by this method are inexpensive to manufacture, highly sensitive and mechanically stable. In addition, they can be adapted to detect various molecules.
The research was carried out with the support of a grant from the Russian Science Foundation and the administration of the Tomsk region. The results of the scientists' work are published in the IEEE Sensors Journal (Q1; IF:4.3).
The development of technologies for manufacturing flexible sensors for biomedical applications is an urgent task of modern science. This is necessary in order to expand the possibilities for continuous monitoring of human health indicators. Electrochemical sensors are the basic components of such systems, used, for example, in inexpensive glucose sensors.
The TERS-Team of the Research School of Chemical and Biomedical Technologies has developed sensors using the technology of multi-stage laser processing of various films of nanomaterials on a polymer substrate. They laser irradiated films of graphene oxide and silver nanoparticles on a polyethylene terephthalate (PET) substrate to produce electrically conductive and durable composites of the required shape. The resulting reduced graphene oxide is one of the most promising materials due to its simple manufacturing technology, high surface area and chemical stability.
The resulting flexible sensor consists of two carbon electrodes — working and auxiliary, and one silver reference electrode. At the same time, optimized laser processing made it possible to create electrodes with low resistance and high sensitivity. And the ability to maintain the internal structural integrity and mechanical properties of the substrate endow the sensors with a high degree of flexibility. The device is able to maintain its properties at more than 1,000 bending cycles," says Maxim Fatkullin, a junior researcher at the TPU Research School of Chemical and Biomedical Technologies.
As part of the study, the scientists demonstrated the practical implementation of a sensor for detecting caffeine. They placed a drop of instant coffee equal to 200 microliters on the sensor. When an electric potential is applied to the sensor, an oxidation process occurs, as a result of which an electrochemical signal is read, which depends on the concentration of the substance. Comparative analysis showed a slight discrepancy of 15% in comparison with the result obtained by high—performance liquid chromatography, the gold standard in analytical chemistry for determining the concentration of various substances.
A similar experiment was successfully conducted with glucose. This makes the sensors developed by polytechnics potentially applicable for the creation of non-invasive and inexpensive medical devices for determining glucose levels.
"The sensors are universal in their principle of operation. They can be modified for specific analytical tasks, to make them highly sensitive for detecting a specific substance. The results obtained make it possible to create flexible and reliable devices based on these sensors that are used in various fields — from health monitoring to environmental sensing," emphasizes Evgenia Sheremet, professor at the TPU Research School of Chemical and Biomedical Technologies.
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