in mid-1945, as World War ii progressed toward its end, the Red Army troops Russian they used a fireplace to be able to communicate by radio. It was relatively easy using two lead plates connected by copper wire. Left one outdoors and the other in the fire. The temperature difference generating a flow of electrons, i.e. electric current. It is known as the Seebeck effect, the same that is now used by researchers from Malaga to any garment textile can produce small amounts of energy, as has been demonstrated in a study published in the journal Advanced Functional Materials. That yes, made with biodegradable materials, sustainable and much lighter: skin of tomato and nanoparticles of graphene, which spread on cotton fabrics as a t-shirt. The dressing, the contrast between body heat and the ambient temperature do the rest.
In a small laboratory of the Faculty of Science of the University of Malaga, Susana Guzman and Alejandro Heredia show a glass jar where they keep what they seem to be a few breakfast cereals. Are not. It is small pieces of cutin, the skin of the tomato. A polymer plant efficient as the container -in the nature protects the fruit from rain, heat, bacteria, or the loss of water – they break down into monomers (small molecules). These are introduced in a solution of water and ethanol coupled to nanoparticles of carbon that make up graphene. When applying heat, the mixture can expand on any tissue -they have chosen cotton be biodegradable – using a spray. The biotinta permeates graphene textile fibers, which clings to them thanks to the tomato skin, which acts as glue. The heat also makes the cutin to polymerize again to become solid. The end result is a black substance that coats the garment and can generate electricity. When the researchers placed a few led lights on it are lit.
“We have achieved a flexible material, lightweight, sustainable and relatively cheap, which generates electricity,” says Manuel Heredia, Ramón y Cajal researcher in the department of Plant breeding and Biotechnology, Institute of Horticulture Subtropical and Mediterranean (IHSM), a joint centre of the Higher Scientific Research Centre (CSIC) and the University of Malaga (UMA). The first application has been a t-shirt, soaked in this solution, generates electricity thanks to the difference between the 36 degrees of body temperature and the outside. The power is still very small. “What is important is that the step is given: now tap to make it better, optimize it and increase the amount of energy generated,” added Heredia. What he is concerned with the obtaining of tomato skin. In Spain is disposed of approximately 60,000 tons per year and the industry is happy to give it to science because you delete them expensive. “And it is a substance which is much more sustainable and cheaper than the tellurium, lead, or germanium, commonly used materials for the manufacture of devices thermoelectric”, says the scientist.
enlarge photo A detail of the research. García-Santos
Heredia works with Susana Guzman, a postdoctoral researcher in the department of Molecular Biology and Biochemistry of the UMA, in the development of new possibilities. As the option to develop garments that will serve the mountaineers, or military who may be in extreme situations and without the possibility of finding a plug. They could also give energy to sensors dedicated to health -such as controlling the heart rate – or measure the levels of pollution that surround us, and even the t-shirt can recharge the mobile phone, or other electronic devices.
“Lower the thermal conduction of the material [the ability to transmit the heat] will allow us to increase the power we can generate,” says Pietro Cataldi, the National Graphene Institute at the University of Manchester and co-author of the published work. The researcher believes that this next generation of biocompuestos in which researchers work in malaga will be higher because, among other things, it will improve your stability during the washing of the tissues. That was the first problem: when Cataldi used polymers derived from petroleum to achieve the Seebeck effect, the materials disappear after a few times through the washing machine. Now the biopolymer from tomato skin works as an adhesive and the graphene remains.
The project has been developed during the last year, half way between the University of Malaga and the Italian Institute of Materials of Genoa, where Heredia and Guzman have worked for seven years. Both returned last spring, the IHSM and the UMA. And Cataldi, who then investigated it there, had asked the collaboration to incorporate the electronics into textile materials. They had already worked together to create a wifi antenna made with the skin of a tomato -like support – and graphene -as a driver – that worked. So when Cataldi asked again for help, continued to investigate with the cutin, which break down with chemical processes in the monomers, and then build a polymer in the laboratory with the size, shape, and properties that you need. It is like a Lego: the disassembled parts of the cutin and, with them, come back to build another figure. “This is not sewing skins”, stresses Manuel Heredia, director of the research group and professor in Biochemistry, knowledge of which has also been a fundamental part of the research. He began to synthesize in the laboratory polymers with properties similar to the skin of the tomato at the beginning of the TWENTY-first century. A work in which you are working since then with Jesus Benitez, the Institute of Materials Science of Seville, in search of new applications.
