Light intensity, temperature, humidity, and salinity - through smart sensing technology, you can record growth indicators related to crop growth one by one to provide a reference for large-scale and high-quality cultivation of crops. However, the real-time monitoring of these indicators requires electric power to drive, but it is often difficult to lay pipelines in agricultural fields. In addition, due to limited battery life and pollution problems, the continuous supply of modern agricultural measurement and monitoring equipment still puzzles people.
Recently, in order to solve such problems, researchers from the Intelligent Bio-Industry Equipment Innovation Team (IBE) of the School of Biosystem Engineering and Food Science of Zhejiang University proposed that natural energy can be tapped out from the agricultural environment and efficiently converted into electrical energy. For the first time, they applied the triboelectric nanogenerator (TENG) technology to agricultural textiles, using the electron transfer and flow during the rain to generate current, collecting raindrops during rainfall, and obtaining energy through energy conversion. Related research results have been published in the journal "Nano Energy".
In the agricultural environment, rainfall is a common phenomenon, but sometimes heavy rainfall and strong rainstorms may adversely affect agricultural production. To this end, agricultural textiles have been widely used, it can provide shade against the sun and rain, to give certain protection to crops. In order to construct a stronger TENG yarn, the researchers developed a simple and effective method for making stretchable electrodes by coating elastic fibers with MXene ink and then naturally developing Ag nanoparticles (AgNPs).
The researchers covered the surface with two layers of special materials - conductive titanium carbide nanomaterials and non-conductive polydimethylsiloxane, which are the key materials to constitute the triboelectric nanogenerator. Titanium carbide induction electrodes not only have high electrical conductivity but also help surface polymers snatch electrons because of their high electronegativity. Polydimethylsiloxane is a common high-molecular polymer that is waterproof and can transfer electrons with rain in the environment.
The researchers pointed out that these two materials have good biocompatibility and on the basis of realizing the original functions of thermal insulation, shading, soil and water conservation, drainage and irrigation, and seed cultivation of agricultural textiles, it can also continuously obtain energy from the natural environment to provide a driving force for smart agriculture.
By continuously coating conductive fibers with PDMS, it can be proved that the triboelectric yarn (diameter about 400 μm) they developed has extraordinary output performance, can generate a voltage of 7.7V, and the effective contact length is 3 cm. In addition, TENG yarn's excellent mechanical properties, high stretchability, excellent durability, and considerable hydrophobicity also enable it to be woven into a mesh or integrated into agricultural fabrics.
Not just rainwater
The researchers said that the yarn can also collect wind energy in the absence of rain. The power source of the triboelectric nano-generator can be natural energy such as wind power, water power, sea waves, etc., or it can be a random energy source such as human walking, hand touch, falling raindrops, etc., or even noise energy such as wheel rotation and roaring of the machine.
Therefore, while providing protection for crop planting and animal husbandry to improve the quality and yield of agricultural products, TENG yarn can also harvest energy from raindrops. In addition, it can also be used as a self-powered sensor to monitor dynamic forces and provide basic information on weather conditions. All in all, this technologically advanced TENG yarn has many advantages, for example, they are easy to be put into engineering design and scale-up in a certain proportion, etc., so it has great potential for use in agricultural textiles to build smart agriculture.
In the future, the greenhouses constructed from these transformed agricultural textiles can not only provide protection by connecting energy storage equipment, improve the quality and yield of agricultural and livestock products, but also can continuously supply electrical energy for IoT sensing devices. Because there is no damage to the environment, this technology can be called green energy technology. It can be seen that the yarn loaded with triboelectric nano-generators can be said to be "living water without " for smart agriculture.
At present, the small-scale TENG yarn can achieve precision, but its large-scale application and promotion still need time. On the one hand, the preparation cost of titanium carbide nanomaterials is relatively high, and there are still some difficulties in promotion, and it is still necessary to find cheap alternative materials; on the other hand, the coating technology of the materials has not yet formed a process, especially the coating thickness needs further exploration. In addition, circuits connection and weaving methods need to be further optimized and improved.
In the next step, the research team will further improve the practical performance of the technology by optimizing the structure, weaving yarns, managing circuits, etc., helping to realize the passive real-time perception of agricultural information and creating a more favorable environment for agricultural green production.